Professor Rahim Tafazolli

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E-mail:
Phone: 01483 68 9834

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Room: 03 CII 02

Publications

Journal articles

  • Zhang L, Xiao P, Zafar A, Quddus A, Tafazolli R. (2016) 'FBMC System: An Insight into Doubly Dispersive Channel Impact'. IEEE IEEE Transactions on Vehicular Technology,
  • Heliot F, Tafazolli R. (2016) 'Optimal Energy-efficient Joint Resource Allocation for Multi-hop MIMO-AF Systems'. IEEE IEEE Transactions on Communications,

    Abstract

    Energy efficiency (EE) is a key enabler for the next generation of communication systems. Equally, resource allocation and cooperative communication are effective tech-niques for improving communication system performance. In this paper, we propose an optimal energy-efficient joint resource allocation method for the multi-hop multiple-input-multiple-output (MIMO) amplify-and-forward (AF) system. We define the joint source and multiple relays optimization problem and prove that its objective function, which is not generally quasiconvex, can be lower-bounded by a convex function. Moreover, all the minima of this objective function are strict minima. Based on these two properties, we then simplify the original multivariate optimization problem into a single variable problem and design a novel approach for optimally solving it in both the unconstraint and power constraint cases. In addition, we provide a sub-optimal approach with reduced complexity; the latter reduces the computational complexity by a factor of up to 40 with near-optimal performance. We finally utilize our novel approach for comparing the optimal energy-per-bit consumption of multi-hop MIMO-AF and MIMO systems; results indicate that MIMO-AF can help to save energy when the direct link quality is poor.

  • Ko Y, Quddus AU, Tafazolli R. (2016) 'Multi-Device Selection Scheduling in Non-Identically Distributed Fading Channels'. IET Communications,
    [ Status: Accepted ]

    Abstract

    Multiuser selection scheduling concept has been recently proposed in the literature in order to increase the multiuser diversity gain and overcome the significant feedback requirements for the opportunistic scheduling schemes. The main idea is that reducing the feedback overhead saves per-user power that could potentially be added for the data transmission. In this work, we propose to integrate the principle of multiuser selection and the proportional fair scheduling scheme. This is aimed especially at power-limited, multi-device systems in non-identically distributed fading channels. For the performance analysis, we derive closed-form expressions for the outage probabilities and the average system rate of the delay-sensitive and the delay-tolerant systems, respectively, and compare them with the full feedback multiuser diversity schemes. The discrete rate region is analytically presented, where the maximum average system rate can be obtained by properly choosing the number of partial devices. We optimize jointly the number of partial devices and the per-device power saving in order to maximize the average system rate under the power requirement. Through our results, we finally demonstrate that the proposed scheme leveraging the saved feedback power to add for the data transmission can outperform the full feedback multiuser diversity, in non-identical Rayleigh fading of devices’ channels.

  • Tang W, Shakir MZ, Imran MA, Tafazolli R, Qaraqe KA, Wang J. (2016) 'Spectral and Energy Efficient Cognitive Radio Aided Heterogeneous Cellular Network with Uplink Power Adaptation'. Wireless Communications and Mobile Computing,
    [ Status: Accepted ]
  • Chen G, Yu G, Xiao P, Tafazolli R. (2016) 'Dual Antenna Selection in Self-Backhauling Multiple Small Cell Networks'. IEEE Communications Letters,

    Abstract

    This paper investigates self-backhauling with dual antenna selection at multiple small cell base stations. Both half and full duplex transmissions at the small cell base station are considered. Depending on instantaneous channel conditions, the full duplex transmission can have higher throughput than the half duplex transmission, but it is not always the case. Closed-form expressions of the average throughput are obtained, and validated by simulation results. In all cases, the dual receive and transmit antenna selection significantly improves backhaul and data transmission, making it an attractive solution in practical systems.

  • Jaber M, Imran MA, Tafazolli R, Tukmanov A. (2016) 'A Distributed SON-based User-Centric Backhaul Provisioning Scheme'. IEEE IEEE Access, , pp. 2314-2330.

    Abstract

    5G definition and standardization projects are well underway, and governing characteristics and major challenges have been identified. A critical network element impacting the potential performance of 5G networks is the backhaul, which is expected to expand in length and breadth to cater to the exponential growth of small cells while offering high throughput in the order of Gbps and less than one-millisecond latency with high resilience and energy efficiency. Such performance may only be possible with direct optical fibre connections which are often not available countrywide and are cumbersome and expensive to deploy. On the other hand, a prime 5G characteristic is diversity, which describes the radio access network, the backhaul, and also the types of user applications and devices. Thus, we propose a novel, distributed, selfoptimized, end-to-end user-cell-backhaul association scheme that intelligently associates users with potential cells based on corresponding dynamic radio and backhaul conditions while abiding by users’ requirements. Radio cells broadcast multiple bias factors, each reflecting a dynamic performance indicator (DPI) of the endto-end network performance such as capacity, latency, resilience, energy consumption, etc. A given user would employ these factors to derive a user-centric cell ranking that motivates it to select the cell with radio and backhaul performance that conforms to the user requirements. Reinforcement learning is used at the radio cell to optimize the bias factors for each DPI in a way that maximizes the system throughput while minimizing the gap between the users’ achievable and required end-to-end quality of experience (QoE). Preliminary results show considerable improvement in users QoE and cumulative system throughput when compared to state-of-theart user-cell association schemes.

  • Zhang L, Quddus A, Katranaras E, Dubben W, Qi Y, Tafazolli R. (2016) 'Performance Analysis and Optimal Cooperative Cluster Size for Randomly Distributed Small Cells under Cloud RAN'. IEEE IEEE Access,
    [ Status: Accepted ]

    Abstract

    One major advantage of cloud/centralized radio access network (C-RAN) is the ease of implementation of multicell coordination mechanisms to improve the system spectrum efficiency (SE). Theoretically, large number of cooperative cells lead to a higher SE, however, it may also cause significant delay due to extra channel state information (CSI) feedback and joint processing computational needs at the cloud data center, which is likely to result in performance degradation. In order to investigate the delay impact on the throughput gains, we divide the network into multiple clusters of cooperative small cells and formulate a throughput optimization problem. We model various delay factors and the sum-rate of the network as a function of cluster size, treating it as the main optimization variable. For our analysis, we consider both base stations’ as well as users’ geometric locations as random variables for both linear and planar network deployments. The output SINR (signal-tointerference-plus-noise ratio) and ergodic sum-rate are derived based on the homogenous Poisson point processing (PPP) model. The sum-rate optimization problem in terms of the cluster size is formulated and solved. Simulation results show that the proposed analytical framework can be utilized to accurately evaluate the performance of practical cloud-based small cell networks employing clustered cooperation.

  • Jaber M, Imran MA, Tafazolli R, Tukmanov A. (2016) '5G Backhaul Challenges and Emerging Research Directions: A Survey'. IEEE Access, 4, pp. 1743-1766.
  • Khalily M, Tafazolli R, Rahman TA, Kamarudin MR. (2016) 'Design of Phased Arrays of Series-Fed Patch Antennas With Reduced Number of the Controllers for 28-GHzmm-Wave Applications'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, 15, pp. 1305-1308.
  • Onireti OS, Akbari I, Imran A, Imran M, Tafazolli R. (2016) 'How Reliable is MDT Based Autonomous Coverage Estimation in the Presence of User and BS Positioning Error?'. IEEE Wireless Communications Letters, 5 (2), pp. 196-199.

    Abstract

    Minimization of drive test (MDT) has recently been standardized by 3GPP as a key self organizing network (SON) feature. MDT allows coverage to be estimated at the base station (BS) using user equipment (UE) measurement reports with the objective to eliminate the need for drive tests. However, most MDT based coverage estimation methods recently proposed in literature assume that UE position is known at the BS with 100% accuracy, an assumption that does not hold in reality. In this paper we develop an analytical model that allows the quantification of error in MDT based autonomous coverage estimation (ACE) as a function of error in UE as well as BS positioning. Our model also allows characterization of error in ACE as function of standard deviation of shadowing.

  • Ma Y, Yamani A, Yi N, Tafazolli R. (2016) 'Low-Complexity MU-MIMO Non-linear Precoding Using Degree-2 Sparse Vector Perturbation'. IEEE IEEE Journal on Selected Areas in Communications, PP (99)

    Abstract

    Multiuser multiple-input multiple-output (MUMIMO) nonlinear precoding techniques face the problem of poor computational scalability to the size of the network. In this paper, the fundamental problem of MU-MIMO scalability is tackled through a novel signal-processing approach, which is called degree-2 vector perturbation (D2VP). Unlike the conventional VP approaches that aim at minimizing the transmit-to-receive energy ratio through searching over an N-dimensional Euclidean space, D2VP shares the same target through an iterative-optimization procedure. Each iteration performs vector perturbation over two optimally selected subspaces. By this means, the computational complexity is managed to be in the cubic order of the size of MUMIMO, and this mainly comes from the inverse of the channel matrix. In terms of the performance, it is shown that D2VP offers comparable bit-error-rate to the sphere encoding approach for the case of small MU-MIMO. For the case of medium and large MU-MIMO when the sphere encoding does not apply due to unimplementable complexity, D2VP outperforms the lattice reduction VP by around 5-10 dB in Eb/No and 10-50 dB in normalized computational complexity.

  • Katsaros K. (2016) 'End-to-End Delay Bound Analysis for Location-based Routing in Hybrid Vehicular Networks'. Vehicular Technology, IEEE Transactions on,
  • Ijaz A, Zhang L, Quddus A, Tafazolli R. (2016) 'HARQ in Relay Assisted Transmission for Machine Type Communications'. IEEE IEEE Wireless Communications Letters, PP (99)

    Abstract

    This letter describes the impact of unknown channel access delay on the timeline of Hybrid Automatic Repeat Request (HARQ) process in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) system when a Relay Node (RN) is used for coverage extension of Machine Type Communication (MTC) devices. A solution is also proposed for the determination of unknown channel access delay when the RN operates in the unlicensed spectrum band. The proposed mechanism is expected to help MTC operation in typical coverage holes areas such as smart meters located in the basement of buildings.

  • Qi Y, Shakir MZ, Imran MA, Qaraqe KA, Quddus AU, Tafazolli R. (2016) 'Fronthaul Data Compression for Uplink CoMP in Cloud Radio Access Network (C-RAN)'. Transactions on Emerging Telecommunications Technologies,
    [ Status: Accepted ]

    Abstract

    The design of efficient wireless fronthaul connections for future heterogeneous networks incorporating emerging paradigms such as cloud radio access network (C-RAN) has become a challenging task that requires the most effective utilization of fronthaul network resources. In this paper, we propose to use distributed compression to reduce the fronthaul traffic in uplink Coordinated Multi-Point (CoMP) for C-RAN. Unlike the conventional approach where each coordinating point quantizes and forwards its own observation to the processing centre, these observations are compressed before forwarding. At the processing centre, the decompression of the observations and the decoding of the user message are conducted in a successive manner. The essence of this approach is the optimization of the distributed compression using an iterative algorithm to achieve maximal user rate with a given fronthaul rate. In other words, for a target user rate the generated fronthaul traffic is minimized. Moreover, joint decompression and decoding is studied and an iterative optimization algorithm is devised accordingly. Finally, the analysis is extended to multi-user case and our results reveal that, in both dense and ultra-dense urban deployment scenarios, the usage of distributed compression can efficiently reduce the required fronthaul rate and a further reduction is obtained with joint operation.

  • Vural S, Wang N, Navaratnam P, Tafazolli R. (2016) 'Caching Transient Data in Internet Content Routers'. IEEE/ACM Transactions on Networking,
    [ Status: Accepted ]
  • Ma Y, De Luna Ducoing JC, Yi N, Tafazolli R. (2015) 'Using Real Constellations in Fully- and Over-loaded Large MU-MIMO Systems with Simple Detection'. IEEE Wireless Communications Letters, PP (99)

    Abstract

    The aim of this letter is to exhibit some advantages of using real constellations in large multi-user (MU) MIMO systems. It is shown that a widely linear zero-forcing (WLZF) receiver with M-ASK modulation enjoys a spatial-domain diversity gain, which linearly increases with the MIMO size even in fully- and over-loaded systems. Using the decision of WLZF as the initial state, the likelihood ascent search (LAS) achieves nearoptimal BER performance in fully-loaded large MIMO systems. Interestingly, for coded systems, WLZF shows a much closer BER to that of WLZF-LAS with a gap of only 0:9-2 dB in SNR.

  • Onireti OS, Imran A, Imran M, Tafazolli R. (2015) 'Energy Efficient Inter-Frequency Small Cell Discovery in Heterogeneous Networks'. IEEE Transactions on Vehicular Technology,
    [ Status: Accepted ]
  • Zhang L, liu W, quddus A, Dianati M, tafazolli R. (2015) 'Adaptive Distributed Beamforming for Relay Networks based on Local Channel State Information'. IEEE IEEE Transactions on Signal and Information Processing over Networks, 1 (2), pp. 117-128.

    Abstract

    Most of the existing distributed beamforming algorithms for relay networks require global channel state information (CSI) at relay nodes and the overall computational complexity is high. In this paper, a new class of adaptive algorithms is proposed which can achieve a globally optimum solution by employing only local CSI. A reference signal based (RSB) scheme is first derived, followed by a constant modulus (CM) based scheme when the reference signal is not available. Considering individual power transmission constraint at each relay node, the corresponding constrained adaptive algorithms are also derived as an extension. An analysis of the overhead and stepsize range for the derived algorithms are then provided and the excess mean square error (EMSE) for the RSB case is studied based on the energy reservation method. As demonstrated by our simulation results, a better performance has been achieved by our proposed algorithms and they have a very low computational complexity and can be implemented on low cost and low processing power devices.

  • Mustafa HA, Imran MA, Shakir MZ, Imran A, Tafazolli R. (2015) 'Coverage Gain and Device-to-Device User Density: Stochastic Geometry Modeling and Analysis'. IEEE Communications Letters, 19 (10), pp. 1742-1745.
  • Mustafa HA, Imran MA, Shakir MZ, Imran A, Tafazolli R. (2015) 'Separation Framework: An Enabler for Cooperative and D2D Communication for Future 5G Networks'. IEEE Communications Surveys and Tutorials, 18 (1), pp. 419-445.
  • Chen H, Maunder RG, Ma Y, Tafazolli R, Hanzo L. (2015) 'Hybrid-ARQ-Aided Short Fountain Codes Designed for Block-Fading Channels'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, 64 (12), pp. 5701-5712.
  • Qi Y, Imran MA, Demo Souza R, Tafazolli R. (2015) 'On the Optimization of Distributed Compression in Multi-Relay Cooperative Networks'. IEEE IEEE Transactions on Vehicular Technology,
    [ Status: Accepted ]

    Abstract

    In this paper, we consider multi-relay cooperative networks for the Rayleigh fading channel, where each relay, upon receiving its own channel observation, independently compresses it and forwards the compressed information to the destination. Although the compression at each relay is distributed using Wyner-Ziv coding, there exists an opportunity for jointly optimizing compression at multiple relays to maximize the achievable rate. Considering Gaussian signalling, a primal optimization problem is formulated accordingly. We prove that the primal problem can be solved by resorting to its Lagrangian dual problem and an iterative optimization algorithm is proposed. The analysis is further extended to a hybrid scheme, where the employed forwarding scheme depends on the decoding status of each relay. The relays that are capable of successful decoding perform decode-and-forward and the rest conduct distributed compression. The hybrid scheme allows the cooperative network to adapt to the changes of the channel conditions and benefit from an enhanced level of flexibility. Numerical results from both spectrum and energy efficiency perspectives show that the joint optimization improves efficiency of compression and identify the scenarios where the proposed schemes outperform the conventional forwarding schemes. The findings provide important insights into the optimal deployment of relays in a realistic cellular network.

  • Shariat M, Pateromichelakis E, Quddus A, Tafazolli R. (2014) 'Joint TDD Backhaul and Access Optimization in Dense Small Cell Networks'. IEEE IEEE Transactions on Vehicular Technology, (99)

    Abstract

    This paper addresses the problem of joint backhaul and access links optimization in dense small cell networks with special focus on time division duplexing (TDD) mode of operation in backhaul and access links transmission. Here, we propose a framework for joint radio resource management where we systematically decompose the problem in backhaul and access links. To simplify the analysis, the procedure is tackled in two stages. At the first stage, the joint optimization problem is formulated for a point-to-point scenario where each small cell is simply associated to a single user. It is shown that the optimization can be decomposed into separate power and subchannel allocation in both backhaul and access links where a set of rate-balancing parameters in conjunction with duration of transmission governs the coupling across both links. Moreover, a novel algorithm is proposed based on grouping the cells to achieve rate-balancing in different small cells. Next in the second stage, the problem is generalized for multi access small cells. Here, each small cell is associated to multiple users to provide the service. The optimization is similarly decomposed into separate sub-channel and power allocation by employing auxiliary slicing variables. It is shown that similar algorithms as previous stage are applicable by slight change with the aid of slicing variables. Additionally, for the special case of line-of-sight backhaul links, simplified expressions for sub-channel and power allocation are presented. The developed concepts are evaluated by extensive simulations in different case studies from full orthogonalization to dynamic clustering and full reuse in the downlink and it is shown that proposed framework provides significant improvement over the benchmark cases.

  • Katranaras E, Imran MA, Dianati M, Tafazolli R. (2014) 'Green inter-cluster interference management in uplink of multi-cell processing systems'. IEEE Transactions on Wireless Communications, 13 (12), pp. 6580-6592.

    Abstract

    © 2014 IEEE.This paper examines the uplink of cellular systems employing base station cooperation for joint signal processing. We consider clustered cooperation and investigate effective techniques for managing inter-cluster interference to improve users' performance in terms of both spectral and energy efficiency. We use information theoretic analysis to establish general closed form expressions for the system achievable sum rate and the users' Bit-per-Joule capacity while adopting a realistic user device power consumption model. Two main inter-cluster interference management approaches are identified and studied, i.e., through: 1) spectrum re-use; and 2) users' power control. For the former case, we show that isolating clusters by orthogonal resource allocation is the best strategy. For the latter case, we introduce a mathematically tractable user power control scheme and observe that a green opportunistic transmission strategy can significantly reduce the adverse effects of inter-cluster interference while exploiting the benefits from cooperation. To compare the different approaches in the context of real-world systems and evaluate the effect of key design parameters on the users' energy-spectral efficiency relationship, we fit the analytical expressions into a practical macrocell scenario. Our results demonstrate that significant improvement in terms of both energy and spectral efficiency can be achieved by energy-aware interference management.

  • Pateromichelakis E, Shariat M, Quddus A, Tafazolli R. (2014) 'Graph-Based Multicell Scheduling in OFDMA-Based Small Cell Networks'. IEEE Access, 2, pp. 897-908.

    Abstract

    This paper proposes a novel graph-based multicell scheduling framework to efficiently mitigate downlink intercell interference in OFDMA-based small cell networks. We define a graph-based optimization framework based on interference condition between any two users in the network assuming they are served on similar resources. Furthermore, we prove that the proposed framework obtains a tight lower bound for conventional weighted sum-rate maximization problem in practical scenarios. Thereafter, we decompose the optimization problem into dynamic graph-partitioning-based subproblems across different subchannels and provide an optimal solution using branch-and-cut approach. Subsequently, due to high complexity of the solution, we propose heuristic algorithms that display near optimal performance. At the final stage, we apply cluster-based resource allocation per subchannel to find candidate users with maximum total weighted sum-rate. A case study on networked small cells is also presented with simulation results showing a significant improvement over the state-of-the-art multicell scheduling benchmarks in terms of outage probability as well as average cell throughput.

  • Al-Imari M, Xiao P, Imran MA, Tafazolli R. (2014) 'Radio Resource Allocation for Uplink OFDMA Systems with Finite Symbol Alphabet Inputs'. IEEE IEEE Transactions on Vehicular Technology, 63 (4), pp. 1917-1921.

    Abstract

    In this paper, we consider the radio resource allocation problem for uplink OFDMA system. The existing algorithms have been derived under the assumption of Gaussian inputs due to its closed-form expression of mutual information. For the sake of practicality, we consider the system with Finite Symbol Alphabet (FSA) inputs, and solve the problem by capitalizing on the recently revealed relationship between mutual information and Minimum Mean-Square Error (MMSE). We first relax the problem to formulate it as a convex optimization problem, then we derive the optimal solution via decomposition methods. The optimal solution serves as an upper bound on the system performance. Due to the complexity of the optimal solution, a low-complexity suboptimal algorithm is proposed. Numerical results show that the presented suboptimal algorithm can achieve performance very close to the optimal solution and outperforms the existing suboptimal algorithms. Furthermore, using our proposed algorithm, significant power saving can be achieved in comparison to the case when Gaussian input is assumed.

  • Pilloni V, Navaratnam P, Vural S, Atzori L, Tafazolli R. (2013) 'TAN: a Distributed Algorithm for Dynamic Task Assignment in WSNs'. IEEE Sensor Networks,
    [ Status: Accepted ]
  • Vural S, Navaratnam P, Wang N, Tafazolli R. (2013) 'Asynchronous Clustering of Multihop Wireless Sensor Networks'. ACM Transactions on Sensor Networks,
    [ Status: Submitted ]
  • Akbari A, Heliot F, Imran MA, Tafazolli R. (2012) 'Energy Efficiency Contours for Broadcast Channels Using Realistic Power Models'. IEEE Transactions on Wireless Communications, 11 (11), pp. 4017-4025.

    Abstract

    Energy savings are becoming a global trend, hence the importance of energy efficiency (EE) as an alternative performance evaluation metric. This paper proposes an EE based resource allocation method for the broadcast channel (BC), where a linear power model is used to characterize the power consumed at the base station (BS). Having formulated our EE based optimization problem and objective function, we utilize standard convex optimization techniques to show the concavity of the latter, and thus, the existence of a unique globally optimal energy-efficient rate and power allocation. Our EE based resource allocation framework is also extended to incorporate fairness, and provide a minimum user satisfaction in terms of spectral efficiency (SE). We then derive the generic equation of the EE contours and use them to get insights about the EE-SE trade-off over the BC. The performances of the aforementioned resource allocation schemes are compared for different metrics against the number of users and cell radius. Results indicate that the highest EE improvement is achieved by using the unconstrained optimization scheme, which is obtained by significantly reducing the total transmit power. Moreover, the network EE is shown to increase with the number of users and decrease as the cell radius increases.

  • He Z, Ma Y, Tafazolli R. (2012) 'A High Accuracy Mobile Positioning Approach in IEEE 802.11a WLANs'. IEICE IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, E95-A (10), pp. 1776-1779.
  • He Z, Ma Y, tafazolli R. (2012) 'Posterior Cramér-Rao Bound for Inertial Sensors Enhanced Mobile Positioning Under The Random Walk Motion Model'. IEEE IEEE Wireless Communications Letters, (99), pp. 1-4.

    Abstract

    This letter presents a new posterior Cramér-Rao bound (PCRB) for inertial sensors enhanced mobile positioning, which performs hybrid data fusion of parameters including position estimates, pedestrian step size, pedestrian heading, and the knowledge of random walk motion model. Moreover, a non-matrix closed form of the PCRB is derived without position estimates. Finally, our numerical results show that when the accuracy of step size and heading measurements is high enough, the knowledge of random walk model becomes redundant.

  • Vural S, Navaratnam P, Tafazolli R. (2012) 'Transmission Range Assignment for Backbone Connectivity in Clustered Wireless Networks'. IEEE Wireless Communications Letters,
  • He Z, Ma Y, Tafazolli R. (2012) 'Opportunistic Cooperative Positioning in OFDMA Systems'. IEICE IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Vol.E95-A (9), pp. 1642-1645.
  • Guo T, Quddus AU, Wang N, Tafazolli R. (2012) 'Local Mobility Management for Networked Femtocells Based on X2 Traffic Forwarding'. IEEE IEEE Transactions on Vehicular Technology,
  • Heliot F, Imran MA, Tafazolli R. (2012) 'Energy-efficient Power Allocation for Point-to-point MIMO System over the Rayleigh Fading Channel'. IEEE IEEE Wireless Communications Letters, 1 (4), pp. 304-307.
  • He Z, Ma Y, Tafazolli R. (2012) 'Training Convergence in Range-based Cooperative Positioning with Stochastic Positional Knowledge'. IEICE IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, E95.A (7), pp. 1200-1204.
  • Xiao P, Tafazolli R, Moessner K, Gluhak A. (2012) 'Codebook Based Single-User MIMO System Design with Widely Linear Processing'. IEEE Transactions on Communications,

    Abstract

    This work addresses joint transceiver optimization for multiple-input, multiple-output (MIMO) systems. In practical systems the complete knowledge of channel state information (CSI) is hardly available at transmitter. To tackle this problem, we resort to the codebook approach to precoding design, where the receiver selects a precoding matrix from a finite set of pre-defined precoding matrices based on the instantaneous channel condition and delivers the index of the chosen precoding matrix to the transmitter via a bandwidth-constraint feedback channel. We show that, when the symbol constellation is improper, the joint codebook based precoding and equalization can be designed accordingly to achieve improved performance compared to the conventional system.

  • Heliot F, Imran MA, Tafazolli R. (2012) 'A Very Tight Approximation of the SISO Energy Efficiency-Spectral Efficiency Trade-Off'. IEEE Communications Letters,

    Abstract

    Beside the well-established spectral-efficiency (SE), energy-efficiency (EE) is currently becoming an important performance evaluation metric, which in turn makes the EE-SE trade-off as a prominent criterion for efficiently designing future communication systems. In this letter, we propose a very tight closed-form approximation (CFA) of this trade-off over the single-input single-output (SISO) Rayleigh flat fading channel. We first derive an improved approximation of the SISO ergodic capacity by means of a parametric function and then utilize it for obtaining our novel EE-SE trade-off CFA, which is also generalized for the symmetric multi-input multi-output channel. We compare our CFA with existing CFAs and show its improved accuracy in comparison with the latter.

  • Cheraghi P, Ma Y, Tafazolli R, Lu Z. (2012) 'Cluster based differential energy detection for spectrum sensing in multi-carrier systems'. IEEE IEEE Transactions on Signal Processing, 60 (12), pp. 6450-6464.
  • Akbari A, Heliot F, Imran MA, Tafazolli R. (2012) 'Energy Efficiency Contours for Broadcast Channels Using Realistic Power Models'. IEEE IEEE Transactions on Wireless Communications, 11 (11), pp. 4017-4025.
  • Pateromichelakis E, Shariat M, Quddus A, Tafazolli R. (2012) 'On the Evolution of Multi-cell Scheduling in 3GPP LTE / LTE-A'. IEEE Communcations Surveys & Tutorials,
  • Heliot F, Imran MA, Tafazolli R. (2012) 'On the Energy Efficiency-Spectral Efficiency Trade-Off over the MIMO Rayleigh Fading Channel'. IEEE IEEE Transactions on Communications, 60 (5), pp. 1345-1356.
  • Imran MA, Imran A, tafazolli R. (2011) 'Relay Station Access Link Spectral Efficiency Optimization through SO of Macro BS Tilts'. IEEE IEEE Communications Letters, 15 (12), pp. 1326-1328.

    Abstract

    In this paper we present a novel framework for spectral efficiency enhancement on the access link between relay stations and their donor base station through Self Organization (SO) of system-wide BS antenna tilts. Underlying idea of framework is inspired by SO in biological systems. Proposed solution can improve the spectral efficiency by upto 1 bps/Hz.

  • Akbari A, Imran MA, Tafazolli R, Dianati M. (2011) 'Energy Efficiency Contours for Single-Carrier Downlink Channels'. IEEE IEEE Communications Letters, 15 (12), pp. 1307-1309.

    Abstract

    Energy efficiency has become an important aspect of wireless communication, both economically and environmentally. This letter investigates the energy efficiency of downlink AWGN channels by employing multiple decoding policies. The overall energy efficiency of the system is based on the bits-per-joule metric, where energy efficiency contours are used to locate the optimal operating points based on the system requirements. Our novel approach uses a linear power model to define the total power consumed at the base station, encompassing the circuit and processing power, and amplifier efficiency, and ensures that the best energy efficiency value can be achieved whilst satisfying other system targets such as QoS and rate-fairness.

  • Wei D, Jin Y, Vural S, Moessner K, Tafazolli R. (2011) 'An Energy-efficient Clustering Solution for Wireless Sensor Networks'. IEEE Transactions on Wireless Communications, United Kingdom: PP (99), pp. 1-11.

    Abstract

    Hot spots in a wireless sensor network emerge as locations under heavy traffic load. Nodes in such areas quickly deplete energy resources, leading to disruption in network services. This problem is common for data collection scenarios in which Cluster Heads (CH) have a heavy burden of gathering and relaying information. The relay load on CHs especially intensifies as the distance to the sink decreases. To balance the traffic load and the energy consumption in the network, the CH role should be rotated among all nodes and the cluster sizes should be carefully determined at different parts of the network. This paper proposes a distributed clustering algorithm, Energy-efficient Clustering (EC), that determines suitable cluster sizes depending on the hop distance to the data sink, while achieving approximate equalization of node lifetimes and reduced energy consumption levels. We additionally propose a simple energy-efficient multihop data collection protocol to evaluate the effectiveness of EC and calculate the end-to-end energy consumption of this protocol; yet EC is suitable for any data collection protocol that focuses on energy conservation. Performance results demonstrate that EC extends network lifetime and achieves energy equalization more effectively than two well-known clustering algorithms, HEED and UCR.

  • Qi Y, Imran MA, Hoshyar R, Tafazolli R. (2011) 'H2-ARQ Relaying: Spectrum and Energy Efficiency Analysis'. IEEE IEEE Journal on Selected Areas in Communications, 29 (8), pp. 1547-1558.

    Abstract

    In this paper, we propose novel Hybrid Automatic Repeat re-Quest (HARQ) strategies used in conjunction with hybrid relaying schemes, named as H^2-ARQ-Relaying. The strategies allow the relay to dynamically switch between amplify-and-forward/compress-and-forward and decode-and-forward schemes according to its decoding status. The performance analysis is conducted from both the spectrum and energy efficiency perspectives. The spectrum efficiency of the proposed strategies, in terms of the maximum throughput, is significantly improved compared with their non-hybrid counterparts under the same constraints. The consumed energy per bit is optimized by manipulating the node activation time, the transmission energy and the power allocation between the source and the relay. The circuitry energy consumption of all involved nodes is taken into consideration. Numerical results shed light on how and when the energy efficiency can be improved in cooperative HARQ. For instance, cooperative HARQ is shown to be energy efficient in long distance transmission only. Furthermore, we consider the fact that the compress-and-forward scheme requires instantaneous signal to noise ratios of all three constituent links. However, this requirement can be impractical in some cases. In this regard, we introduce an improved strategy where only partial and affordable channel state information feedback is needed.

  • Ma Y, Tafazolli R, Zhang Y, Qian C. (2011) 'Adaptive Modulation for Opportunistic Decode-and-Forward Relaying'. IEEE IEEE Transactions on Wireless Communications, 10 (7), pp. 2017-2022.
  • Akbari A, Imran MA, Hoshyar R, Amich A, Tafazolli R. (2011) 'Average Energy Efficiency Contours with Multiple Decoding Policies'. IEEE IEEE Communications Letter, 15 (5), pp. 506-508.

    Abstract

    This letter addresses energy-efficient design in multi-user, single-carrier uplink channels by employing multiple decoding policies. The comparison metric used in this study is based on average energy efficiency contours, where an optimal rate vector is obtained based on four system targets: Maximum energy efficiency, a trade-off between maximum energy efficiency and rate fairness, achieving energy efficiency target with maximum sum-rate and achieving energy efficiency target with fairness. The transmit power function is approximated using Taylor series expansion, with simulation results demonstrating the achievability of the optimal rate vector, and negligible performance difference in employing this approximation.

  • Hanzo II L, Tafazolli R. (2011) 'The effects of shadow-fading on QoS-aware routing and admission control protocols designed for multi-hop MANETs'. Wireless Communications and Mobile Computing, 11 (1), pp. 1-22.
  • Hanzo L, Tafazolli R. (2011) 'QoS-aware routing and admission control in shadow-fading environments for multirate MANETs'. IEEE Transactions on Mobile Computing, 10 (5), pp. 622-637.
  • Akbari A, Imran MA, Hoshyar R, Amich A, Tafazolli R. (2011) 'Average energy efficiency contours with multiple decoding policies'. IEEE Communications Letters, 15 (5), pp. 506-508.
  • Héliot F, Hoshyar R, Tafazolli R. (2011) 'An accurate closed-form approximation of the distributed MIMO outage probability'. IEEE Transactions on Wireless Communications, 10 (1), pp. 5-11.
  • Quddus AU, Guo T, Shariat M, Hunt B, Imran A, Ko Y, Tafazolli R. (2010) 'Next Generation Femtocells: An Enabler for High Efficiency Multimedia Transmission'. IEEE IEEE Comsoc MMTC E-Letters, 5 (5), pp. 27-31.
  • Yi N, Ma Y, Tafazolli R. (2010) 'Underlay Cognitive Radio with Full or Partial Channel Quality Information'. International Journal of Navigation and Observation, 2010 Article number 105723
  • Dianati M, Tafazolli R, Shen XS, Naik K. (2010) 'Call admission control with opportunistic scheduling scheme'. JOHN WILEY & SONS INC WIRELESS COMMUNICATIONS & MOBILE COMPUTING, 10 (3), pp. 372-382.
  • Zhang Y, Ma Y, Tafazolli R. (2010) 'Power Allocation for Bidirectional AF Relaying over Rayleigh Fading Channels'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE COMMUNICATIONS LETTERS, 14 (2), pp. 145-147.
  • Dianati M, Tafazolli R, Shen X, Naik K. (2010) 'Per-user service model for opportunistic scheduling scheme over fading channels'. JOHN WILEY & SONS INC WIRELESS COMMUNICATIONS & MOBILE COMPUTING, 10 (1), pp. 87-100.
  • Hoshyar R, Shariat M, Tafazolli R. (2010) 'Subcarrier and Power Allocation with Multiple Power Constraints in OFDMA Systems'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE COMMUNICATIONS LETTERS, 14 (7), pp. 644-646.
  • Movahhedian M, Ma Y, Tafazolli R. (2010) 'Blind CFO Estimation for Linearly Precoded OFDMA Uplink'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON SIGNAL PROCESSING, 58 (9), pp. 4698-4710.
  • Bennis M, Wijting C, Abedi S, Thilakawardana S, Tafazolli R. (2009) 'Performance evaluation of advanced spectrum functionalities for future radio networks'. JOHN WILEY & SONS INC WIRELESS COMMUNICATIONS & MOBILE COMPUTING, 9 (11), pp. 1532-1542.
  • Shariat M, Quddus AU, Ghorashi SA, Tafazolli R. (2009) 'Scheduling as an Important Cross-Layer Operation for Emerging Broadband Wireless Systems'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE COMMUNICATIONS SURVEYS AND TUTORIALS, 11 (2), pp. 74-86.
  • Heliot F, Chu X, Hoshyar R, Tafazolli R. (2009) 'A Tight Closed-Form Approximation of the Log-Normal Fading Channel Capacity'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, 8 (6), pp. 2842-2847.
  • Hanzo L, Tafazolli R. (2009) 'Admission Control Schemes for 802.11-Based Multi-Hop Mobile Ad hoc Networks: A Survey'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE COMMUNICATIONS SURVEYS AND TUTORIALS, 11 (4), pp. 78-108.
  • Bennis M, Kermoal J-P, Ojanen P, Lara J, Abedi S, Pintenet R, Thilakawardana S, Tafazolli R. (2009) 'Advanced Spectrum Functionalities for Future Radio Networks'. SPRINGER WIRELESS PERSONAL COMMUNICATIONS, 48 (1), pp. 175-191.
  • Abaii M, Liu Y, Tafazolli R. (2008) 'An efficient resource allocation strategy for future wireless cellular systems'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, 7 (8), pp. 2940-2949.
  • Thilakawardana D, Moessner K, Tafazolli R. (2008) 'Darwinian approach for dynamic spectrum allocation in next generation systems'. INST ENGINEERING TECHNOLOGY-IET IET COMMUNICATIONS, 2 (6), pp. 827-836.
  • Ma Y, Yi N, Tafazolli R. (2008) 'Bit and power loading for OFDM-based three-node relaying communications'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON SIGNAL PROCESSING, 56 (7), pp. 3236-3247.
  • Wang Y, Fan L, He D, Tafazolli R. (2008) 'Performance comparison of scheduling algorithms in network mobility environment'. ELSEVIER SCIENCE BV COMPUTER COMMUNICATIONS, 31 (9), pp. 1727-1738.
  • Hoshyar R, Wathan PP, Tafazolli R. (2008) 'Novel low-density signature for synchronous CDMA systems over AWGN channel'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON SIGNAL PROCESSING, 56 (4), pp. 1616-1626.
  • Wathan F, Hoshyar R, Tafazolli R. (2008) 'Dynamic grouped chip-level iterated multiuser detection based on Gaussian forcing technique'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE COMMUNICATIONS LETTERS, 12 (3), pp. 167-169.
  • Wang Y, Fan L, He D, Tafazolli R. (2008) 'Solution to weight-adaptive fair queuing'. INST ENGINEERING TECHNOLOGY-IET ELECTRON LETT, 44 (5), pp. 385-387.
  • Zhang Y, Hoshyar R, Tafazolli R. (2008) 'Timing and frequency offset estimation scheme for the uplink of OFDMA systems'. INST ENGINEERING TECHNOLOGY-IET IET COMMUNICATIONS, 2 (1), pp. 121-130.
  • Navaratnam P, Cruickshank H, Tafazolli R. (2008) 'A link adaptive transport protocol for multimedia streaming applications in multi hop wireless networks'. SPRINGER MOBILE NETWORKS & APPLICATIONS, 13 (3-4), pp. 246-258.
  • Huy DTP, Rodriguez J, Gameiro A, Tafazolli R. (2007) 'Dynamic resource allocation for beyond 3G cellular networks'. SPRINGER WIRELESS PERSONAL COMMUNICATIONS, 43 (4), pp. 1727-1740.
  • Mozaffaripour M, Tafazolli R. (2007) 'Suboptimal search algorithm in conjunction with polynomial-expanded linear multiuser detector for FDD WCDMA mobile uplink'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, 56 (6), pp. 3600-3606.
  • Li Z, Tafazolli R. (2007) 'Location management for packet switched services in 3G partnership project networks'. INST ENGINEERING TECHNOLOGY-IET IET COMMUNICATIONS, 1 (4), pp. 562-569.
  • Widiawan AK, Tafazolli R. (2007) 'High altitude platform station (HAPS): A review of new infrastructure development for future wireless communications'. SPRINGER WIRELESS PERSONAL COMMUNICATIONS, 42 (3), pp. 387-404.
  • Gluhak A, Inoue M, Moessner K, Tafazolli R. (2007) 'Signaling channel for coordinated multicast service delivery in next generation wireless networks'. IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG IEICE TRANSACTIONS ON COMMUNICATIONS, E90B (7), pp. 1780-1790.
  • Ma Y, Tafazolli R. (2007) 'Estimation of carrier frequency offset for multicarrier CDMA uplink'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON SIGNAL PROCESSING, 55 (6), pp. 2617-2627.
  • Ma Y, Tafazolli R. (2007) 'Channel estimation for OFDMA uplink: a hybrid of linear and BEM interpolation approach'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON SIGNAL PROCESSING, 55 (4), pp. 1568-1573.
  • Dohler M, McLaughlin S, Lee Y, Tafazolli R. (2007) 'Implementable wireless access for B3G networks - Part IV: Resource management issues'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE COMMUNICATIONS MAGAZINE, 45 (3), pp. 106-111.
  • Georgiades M, Akhtar N, Politis C, Tafazolli R. (2007) 'Enhancing mobility management protocols to minimise AAA impact on handoff performance'. ELSEVIER SCIENCE BV COMPUTER COMMUNICATIONS, 30 (3), pp. 608-618.
  • Presser M, Brown T, Goulianos A, Stavrou S, Tafazolli R. (2007) 'Body centric context aware application scenarios'. IET Seminar Digest, 2007 (11803), pp. 19-25.
  • Huang L, Chew KA, Thilakawardana S, Liu Y, Moessner K, Tafazolli R. (2006) 'Efficient group-based multimedia-on-demand service delivery in wireless networks'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE TRANSACTIONS ON BROADCASTING, 52 (4), pp. 492-504.
  • Rodriguez V, Moessner K, Tafazolli R. (2006) 'Market driven dynamic spectrum allocation over space and time among radio-access networks: DVB-T and B3G CDMA with heterogeneous terminals'. SPRINGER MOBILE NETWORKS & APPLICATIONS, 11 (6), pp. 847-860.
  • Huang L, Liu Y, Thilakawardana S, Tafazolli R. (2006) 'Network-centric user assignment in the next generation mobile networks'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE COMMUNICATIONS LETTERS, 10 (12), pp. 822-824.
  • Rodriguez V, Moessner K, Tafazolli R. (2006) 'Market driven dynamic spectrum allocation over space and time among radio-access networks: DVB-T and B3G CDMA with heterogeneous terminals'. Multibody System Dynamics, 16 (4), pp. 847-860.
  • Liu Y, Hoshyar R, Yang X, Tafazolli R. (2006) 'Integrated radio resource allocation for multihop cellular networks with fixed relay stations'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, 24 (11), pp. 2137-2146.
  • Ma Y, Yi N, Tafazolli R. (2006) 'Channel estimation for PIRP-OFDM in slowly time-varying channel: First-order or second-order statistics?'. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC IEEE SIGNAL PROCESSING LETTERS, 13 (3), pp. 129-132.
  • Hoshyar R, Wathan FP, Tafazolli R. (2006) 'Novel Low-Density Signature structure for synchronous DS-CDMA systems'. GLOBECOM - IEEE Global Telecommunications Conference,

    Abstract

    Novel Low-Density Signature (LDS) structure is proposed for synchronous Code Division Multiple Access (CDMA) systems for an uplink communication over AWGN channel. It arranges the system such that the interference pattern being seen by each user at each received sampled chip is different. Furthermore, new near-optimum chip-level iterative multiuser decoder is suggested to exploit the proposed structure. It is shown via computer simulations that, without forward error correction (FEC) coding, the proposed LDS structure could achieve near single-user performance with up to 200% loading condition. As the proposed iterative decoding converges relatively fast, the complexity is kept much more affordable than that of optimum multiuser detection (MUD) with conventional structure. © 2006 IEEE.

  • Prammanee S, Moessner K, Tafazolli R. (2006) 'Discovering modalities for adaptive multimodal interfaces'. Interactions, 13 (3), pp. 66-70.
  • Georgiades M, Dagiuklas T, Tafazolli R. (2006) 'Middlebox context transfer for multimedia session support in all-IP networks'. IWCMC 2006 - Proceedings of the 2006 International Wireless Communications and Mobile Computing Conference, 2006, pp. 389-394.

Conference papers

  • Kuzminskiy A, Abramovich Y, Xiao P, Tafazolli R. (2016) 'Spectrum Sharing Efficiency Analysis in Rule Regulated Networks with Decentralized Occupation Control'. IEEE Valencia, Spain: IEEE PIMRC 2016
    [ Status: Accepted ]
  • Zhang L, Ijaz A, Xiao P, Quddus A, Tafazolli R. (2016) 'Single-rate and Multi-rate Multi-service Systems for Next Generation and Beyond Communications'. IEEE Valencia, Spain: 27th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications
    [ Status: Accepted ]

    Abstract

    To flexibly support diverse communication requirements (e.g., throughput, latency, massive connection, etc.) for the next generation wireless communications, one viable solution is to divide the system bandwidth into several service subbands, each for a different type of service. In such a multi-service (MS) system, each service has its optimal frame structure while the services are isolated by subband filtering. In this paper, a framework for multi-service (MS) system is established based on subband filtered multi-carrier (SFMC) modulation. We consider both single-rate (SR) and multi-rate (MR) signal processing as two different MS-SFMC implementations, each having different performance and computational complexity. By comparison, the SR system outperforms the MR system in terms of performance while the MR system has a significantly reduced computational complexity than the SR system. Numerical results show the effectiveness of our analysis and the proposed systems. These proposed SR and MR MS-SFMC systems provide guidelines for next generation wireless system frame structure optimization and algorithm design.

  • Onireti OS, Imran A, Imran M, Tafazolli R. (2016) 'Impact of Positioning Error on Achievable Spectral Efficiency in Database-aided Networks'. Kuala Lumpur, Malaysia: IEEE International Conference on Communications
    [ Status: Accepted ]
  • Chandrasekaran G, Wang N, Jun J, Xu M, Tafazolli R. (2016) 'Towards D2D-based Opportunistic Data Relay Service in Partial Not-spots'. IEEE New York, USA: WiMob'2016
    [ Status: Accepted ]
  • Nikitopoulos K, Chatzipanagiotis D, Jayawardena C, Tafazolli R. (2016) 'MultiSphere: Massively Parallel Tree Search for Large Sphere Decoders'. IEEE IEEE GLOBECOM 2016 Proceedings, Washington, DC: IEEE GLOBECOM 2016
    [ Status: Accepted ]
  • Akbari I, Onireti O, Imran A, Imran MA, Tafazolli R. (2015) 'Impact of inaccurate user and base station positioning on autonomous coverage estimation.'. IEEE CAMAD, , pp. 114-118.
  • Kiyumi RA, Vural S, Foh CH, Tafazolli R. (2015) 'A distributed sleep mechanism for energy-efficiency in non-beacon-enabled IEEE 802.15.4 networks.'. IEEE CAMAD, , pp. 237-241.
  • Onireti OS, Mohamed A, Imran MA, Tafazolli R. (2015) 'Correlation-based Adaptive Pilot Pattern in Control/Data Separation Architecture'. IEEE 2015 IEEE International Conference on Communications (ICC), London: IEEE International Conference on Communications, pp. 2233-2238.

    Abstract

    Most of the wireless systems such as the long term evolution (LTE) adopt a pilot symbol-aided channel estimation approach for data detection purposes. In this technique, some of the transmission resources are allocated to common pilot signals which constitute a significant overhead in current standards. This can be traced to the worst-case design approach adopted in these systems where the pilot spacing is chosen based on extreme condition assumptions. This suggests extending the set of the parameters that can be adaptively adjusted to include the pilot density. In this paper, we propose an adaptive pilot pattern scheme that depends on estimating the channel correlation. A new system architecture with a logical separation between control and data planes is considered and orthogonal frequency division multiplexing (OFDM) is chosen as the access technique. Simulation results show that the proposed scheme can provide a significant saving of the LTE pilot overhead with a marginal performance penalty.

  • Pateromichelakis E, Shariat M, Quddus A, Tafazolli R. (2015) 'Joint Routing and Scheduling in Dense Small Cell Networks using 60GHz backhaul'. London: IEEE ICC 2015 - Workshop on Cloud-Processing in Heterogeneous Mobile Communication Networks (IWCPM)
    [ Status: Accepted ]
  • Onireti OS, Imran A, Imran MA, Tafazolli R. (2015) 'On Energy Efficient Inter-Frequency Small Cell Discovery in Heterogeneous Networks'. IEEE 2015 IEEE International Conference on Communications (ICC), London: IEEE International Conference on Communications, pp. 13-18.

    Abstract

    In this paper, we investigate the optimal inter- frequency small cell discovery (ISCD) periodicity for small cells deployed on carrier frequency other than that of the serving macro cell. We consider that the small cells and user terminals (UTs) positions are modeled according to a homogeneous Poisson Point Process (PPP). We utilize polynomial curve fitting to approximate the percentage of time the typical UT misses small cell offloading opportunity, for a fixed small cell density and fixed UT speed. We then derive analytically, the optimal ISCD periodicity that minimizes the average UT energy consumption (EC). Furthermore, we also derive the optimal ISCD periodicity that maximizes the average energy efficiency (EE), i.e. bit- per-joule capacity. Results show that the EC optimal ISCD periodicity always exceeds the EE optimal ISCD periodicity, with the exception of when the average ergodic rate in both tiers are equal, in which the optimal ISCD periodicity in both cases also becomes equal.

  • Vural S, Navaratnam P, Wang N, Tafazolli R. (2014) 'Asynchronous Clustering of Multihop Wireless Sensor Networks'. IEEE IEEE International Conference on Communications (ICC), 2014, Sydney, Australia: IEEE ICC, pp. 472-477.
  • Onireti OS, Mohamed A, Qi Y, Imran A, Imran MA, Tafazolli R. (2014) 'Physical Layer Frame in Signalling-Data Separation Architecture: Overhead and Performance Evaluation'. VDE Barcelona, Spain: European Wireless 2014
  • Onireti OS, Akbari I, Imran MA, Imran A, Tafazolli R. (2014) 'Effect of Inaccurate Position Estimation on Self-Organising Coverage Estimation in Cellular Networks'. VDE Barcelona, Spain: European Wireless 2014, pp. 176-180.

    Abstract

    Requirement for low operating and deployment costs of cellular networks motivate the need for self-organisation in cellular networks. To reduce operational costs, self-organising networks are fast becoming a necessity. One key issue in this context is self-organised coverage estimation that is done based on the signal strength measurement and reported position information of system users. In this paper, the effect of inaccurate position estimation on self-organised coverage estimation is investigated. We derive the signal reliability expression (i.e. probability of the received signal being above a certain threshold) and the cell coverage expressions that take the error in position estimation into consideration. This is done for both the shadowing and non-shadowing channel models. The accuracy of the modified reliability and cell coverage probability expressions are also numerically verified for both cases.

  • Pilloni V, Navaratnam P, Vural S, Atzori L, Tafazolli R. (2013) 'Cooperative Task Assignment for Distributed Deployment of Applications in WSNs'. Budapest, Hungary: IEEE International Conference on Communications (ICC 2013)
  • Akbari A, Imran MA, Tafazolli R. (2011) 'Maximising Average Energy efficiency for Two-user AWGN Broadcast Channel'. Warsaw, Poland : IEEE Future Network and Mobile Summit, Warsaw: Future Network & Mobile Summit (FutureNetw), 2011

    Abstract

    Energy consumption has become an increasingly important aspect of wireless communications, from both an economical and environmental point of view. New enhancements are being placed on mobile networks to reduce the power consumption of both mobile terminals and base stations. This paper studies the achievable rate region of AWGN broadcast channels under Time-division, Frequency-division and Superposition coding, and locates the optimal energy-efficient rate-pair according to a comparison metric based on the average energy efficiency of the system. In addition to the transmit power, circuit power and signalling power are also incorporated in the energy efficiency function, with simulation results verifying that the Superposition coding scheme achieves the highest energy efficiency in an ideal, but non-realistic scenario, where the signalling power is zero. With moderate signalling power, the Frequency-division scheme is the most energy-efficient, with Superposition coding and Time-division becoming second and third best. Conversely, when the signalling power is high, both Time-division and Frequency-division schemes outperform Superposition coding. On the other hand, the Superposition coding scheme also incorporates rate-fairness into the system, which allows both users to transmit whilst maximising the energy efficiency.

  • Yi N, Ma Y, Tafazolli R. (2011) 'Incremental Decode-Forward Relaying over Asymmetric Fading Channels: Outage Probability and Location-Aided Relay Selection'. Nice, France: IEEE SSP'11, pp. 181-184.
  • Imran MA, Tang W, Tafazolli R. (2011) 'Coordination of Energy Efficient Sensing and Transmission in Cognitive Radio Networks'. Liverpool, UK: PGNET Liverpool
  • Heliot F, Imran MA, tafazolli R. (2011) 'On the Energy Efficiency Gain of MIMO Communication under Various Power Consumption Models'. Warsaw, Poland: ICT Future Network & Mobile Summit
  • Yi N, Ma Y, Tafazolli R. (2011) 'Cooperative iterative water-filling for two-user Gaussian frequency-selective interference chanels'. Budapest: IEEE VTC'11
  • Hoseinitabatabaei SA, Gluhak A, Tafazolli R. (2011) 'uDirect: A novel approach for pervasive observation of user direction with mobile phones'. 2011 IEEE International Conference on Pervasive Computing and Communications, PerCom 2011, , pp. 74-83.

    Abstract

    In this paper we present the uDirect algorithm as a novel approach for mobile phone centric observation of a user's facing direction, through which the device and user orientations relative to earth coordinate are estimated. While the device orientation estimation is based on accelerometer and magnetometer measurements in standing mode, the unique behavior of measured acceleration during stance phase of a human's walking cycle is used for detecting user direction. Furthermore, the algorithm is independent of initial orientation of the device which gives the user higher space of freedom for long term observations. As the algorithm only relies on embedded accelerometer and magnetometer sensors of the mobile phone, it is not susceptible to shadowing effect as GPS. In addition, by performing independent estimations during each step of walking the model is robust to error accumulation. Evaluating the algorithm with 180 data samples from 10 participates has empirically confirmed the assumptions of our analytical model about the unique characteristics of the human stance phase for direction estimation. Moreover, our initial inspection has shown a system based on our algorithm outperforms conventional use of GPS and PCA analysis based techniques for walking distances more than 2 steps. © 2011 IEEE.

  • Lu Z, Ma Y, Tafazolli R. (2010) 'A first-order cyclostationarity based energy detection approach for non-cooperative spectrum sensing'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, , pp. 554-559.

    Abstract

    Spectrum sensing is one of key enabling techniques to advanced radio technologies such as cognitive radios and ALOHA. This paper presents a novel non-cooperative spectrum sensing approach that can achieve a good trade-off between latency, reliability and computational complexity. Our major idea is to exploit the first-order cyclostationarity of the primary user's signal to reduce the noise-uncertainty problem inherent in the conventional energy detection approach. It is shown that the proposed approach is suitable for detecting the primary user's activity in the interweave paradigm of cognitive spectrum sharing, while the active primary user is periodically sending training sequence. Computer simulations are carried out for the typical IEEE 802.11g system. It is observed that the proposed approach outperforms both the energy detection and the second-order cyclostationarity approach when the observation period is more than 10 frames corresponding to 0.56 ms. ©2010 IEEE.

  • Han C, Dianati M, Tafazolli R, Kernchen R. (2010) 'Throughput Analysis of the IEEE 802.11p Enhanced Distributed Channel Access Function in Vehicular Environment'. Ottowa, Canada: 72nd IEEE Vehicular Technology Conference, pp. 1-5.
  • Mach T, Tafazolli R. (2010) 'Battery life idle parameter optimization of UE in self organizing network'. IEEE 21st International Symposium on Personal, Indoor and Mobile Radio Communications, Instanbul, Turkey: 21st PIMRC 2010, pp. 1332-1336.
  • Imran A, Imran MA, Tafazolli R. (2010) 'A novel self organizing framework for adaptive frequency reuse and deployment in future cellular networks'. 21st IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, Instanbul, Turkey: 21st PIMRC 2009, pp. 2354-2359.
  • Auer G, Godor I, Hevizi L, Imran M, Tafazolli R. (2010) 'Enablers for Energy Efficient Wireless Networks'. Ottawa, Canada : IEEE Green Wireless Communications and Networks Workshop � GreeNet, Proc. IEEE VTC Fall 2010, Vehicular Technology Conference Fall (VTC 2010-Fall), 2010 IEEE 72nd, pp. 1-5.

    Abstract

    Mobile communications are increasingly contributing to global energy consumption. The EARTH (Energy Aware Radio and neTworking tecHnologies) project tackles the important issue of reducing CO emissions by enhancing the energy efficiency of cellular mobile networks. EARTH is a holistic approach to develop a new generation of energy efficient products, components, deployment strategies and energy-aware network management solutions. In this paper the holistic EARTH approach to energy efficient mobile communication systems is introduced. Performance metrics are studied to assess the theoretical bounds of energy efficiency as well as the practical achievable limits. A vast potential for energy savings lies in the operation of radio base stations. In particular, base stations consume a considerable amount of the available power budget even when operating at low load. Energy efficient radio resource management (RRM) strategies need to take into account slowly changing daily load patterns, as well as highly dynamic traffic fluctuations. Moreover, various deployment strategies are examined focusing on their potential to reduce energy consumption, whilst providing uncompromised coverage and user experience. This includes heterogeneous networks with a sophisticated mix of different cell sizes, which may be further enhanced by energy efficient relaying and base station cooperation technologies. Finally, scenarios leveraging the capability of advanced terminals to operate on multiple radio access technologies (RAT) are discussed with respect to their energy savings potential. ©2010 IEEE.

  • Héliot F, Hoshyar R, Tafazolli R. (2010) 'Power Allocation for the Downlink of Nonregenerative Cooperative Multi-User MIMO Communication system'. Proc. IEEE PIMRC, Istanbul, Turkey: IEEE PIMRC
  • Héliot F, Hoshyar R, Tafazolli R. (2010) 'On the spectral efficiency maximization of Nonregenerative Cooperative MIMO Communication Systems'. Proc. IEEE PIMRC, Istanbul, Turkey: IEEE PIMRC
  • Wei D, Navaratnam P, Gluhak A, Tafazolli R. (2010) 'Energy-efficient Clustering for Wireless Sensor Networks with Unbalanced Traffic Load'. IEEE IEEE Wireless Communications and Networking conference, Sydney: IEEE Wireless Communications & Networking Conference
  • Héliot F, Hoshyar R, Tafazolli R. (2010) 'Low-Complexity Power Allocation Schemes for the Downlink of Nonregenerative Cooperative Multi-User MIMO Communication System'. Proc. ICT Future Network & Mobile Summit, Florence, Italy: ICT Future Network & Mobile Summit
  • Abangar H, Ghader M, Gluhak A, Tafazolli R. (2010) 'Improving the Performance of Web Services in Wireless Sensor Networks'. Florence, Italy: Future Network & Mobile Summit 2010
  • Héliot F, Hoshyar R, Tafazolli R. (2010) 'Weighted Sum-Rate based Power Allocation for the Uplink of Nonregenerative Cooperative Multi-User MIMO Communication System'. Proc. ICT Future Network & Mobile Summit, Florence, Italy: ICT Future Network & Mobile Summit
  • Guo T, Wang N, Tafazolli R, Moessner K. (2010) 'Policy-Aware Virtual relay placement for inter-domain path diversity'. Proc. IEEE Symp. Computers and Communications (ISCC), , pp. 38-43.
  • Fazel Falavarjani MS, Hoshyar R, Tafazolli R. (2010) 'Performance evaluation of a flexible amplify and forward (AF) combined with HARQ'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, , pp. 488-493.
  • Chatzimisios P, Dagiuklas T, Tafazolli R, Verikoukis C. (2010) 'Message from ConWire'10 co-chairs'. Proceedings - International Conference on Computer Communications and Networks, ICCCN,
  • Rodriguez J, Marques P, Radwan A, Moessner K, Tafazolli R, Raspopoulos M, Stavrou S, Trapps P, Noquet D, Sithamparanathan K, Gomes A, Piesiewicz R, Mokrani H, Foglar A, Verikoukis C. (2010) 'Cognitive radio and cooperative strategies for power saving in multi-standard wireless devices'. 2010 Future Network and Mobile Summit,
  • Dianati M, Tafazolli R, Moessner K. (2010) 'Enabling Tussle-Agile Inter-networking Architectures by Underlay Virtualisation'. SPRINGER-VERLAG BERLIN FUTURE INTERNET - FIS 2009, Berlin, GERMANY: 2nd Future Internet Symposium (FIS 2009) 6152, pp. 81-95.
  • Zhang Y, Ma Y, Tafazolli R. (2010) 'Modulation-adaptive cooperation in Rayleigh fading channels with imperfect CSI'. IWCMC 2010 - Proceedings of the 6th International Wireless Communications and Mobile Computing Conference, , pp. 148-152.
  • Qi Y, Hoshyar R, Tafazolli R. (2010) 'A novel decoding structure in compress-and-forward systems'. IWCMC 2010 - Proceedings of the 6th International Wireless Communications and Mobile Computing Conference, , pp. 412-416.
  • He Z, Ma Y, Tafazolli R, Liu H. (2010) 'An oversampling approach for LoS-ToA estimation in interleaved OFDMA'. IWCMC 2010 - Proceedings of the 6th International Wireless Communications and Mobile Computing Conference, , pp. 580-584.
  • Wei D, Jin Y, Gluhak A, Tafazolli R, Moessner K. (2010) 'Hot-spot issue aware clustering for WSNs to extend stable operation period'. 2010 Future Network and Mobile Summit,
  • Qi Y, Imran M, Tafazolli R. (2010) 'On the energy aware deployment strategy in cellular systems'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, , pp. 363-367.
  • Akbari A, Hoshyar R, Tafazolli R. (2010) 'Energy-efficient resource allocation in wireless OFDMA systems'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, , pp. 1731-1735.
  • Qi Y, Hoshyar R, Tafazolli R. (2010) 'A novel hybrid relaying scheme using multilevel coding'. IEEE Vehicular Technology Conference,
  • Georgoulas S, Moessner K, McAleer B, Tafazolli R. (2010) 'Towards efficient protocol design through protocol profiling and verification of performance and operational metrics'. IWCMC 2010 - Proceedings of the 6th International Wireless Communications and Mobile Computing Conference, , pp. 848-852.
  • Qi Y, Hoshyar R, Tafazolli R. (2010) 'The error-resilient compression of correlated binary sources and EXIT chart based performance evaluation'. Proceedings of the 2010 7th International Symposium on Wireless Communication Systems, ISWCS'10, , pp. 741-745.
  • Kosta C, Sodunke T, Shateri M, Tafazolli R. (2010) 'Two-stage call admission control policy for LTE Systems'. IWCMC 2010 - Proceedings of the 6th International Wireless Communications and Mobile Computing Conference, , pp. 1101-1105.
  • Imran A, Imran MA, Tafazolli R. (2010) 'A new performance characterization framework for deployment architectures of next generation distributed cellular networks'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, , pp. 2046-2051.
  • Georgoulas S, Moessner K, Mcaleer B, Tafazolli R. (2010) 'Using Formal Verification Methods and Tools for Protocol Profiling and Performance Assessment in Mobile and Wireless Environments'. IEEE 2010 IEEE 21st International Symposium on Personal Indoor and Mobile Radio Communications, Istanbul, Turkey: PIMRC 2010, pp. 2471-2476.
  • Mostafavi SM, Hamadani E, Tafazolli R. (2010) 'Delay minimization in multipath routing'. IWCMC 2010 - Proceedings of the 6th International Wireless Communications and Mobile Computing Conference, , pp. 711-715.
  • Salami G, Tafazolli R. (2009) 'A two stage genetically inspired algorithm for spectrum sharing between two UMTS operators'. International Conference on Ultra Modern Telecommunications & Workshops, St. Petersburg, Russia: ICUMT '09
  • Salami GK, Tafazolli R. (2009) 'A framework for UMTS inter-operator spectrum sharing in the UMTS extension band'. IEEE 9th International Symposium on Communications and Information Technology, Icheon, South Korea: 9th ISCIT 2009, pp. 193-198.
  • Yi N, Ma Y, Tafazolli R. (2009) 'Coexistence Strategies and Capacity Theorems of Interference Awareness Cognitive Radio'. IEEE 2009 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATION WORKSHOPS, VOLS 1 AND 2, Dresden, GERMANY: IEEE International Conference on Communications (ICC 2009), pp. 644-648.
  • Heliot F, Hoshyar R, Tafazolli R. (2009) 'A CLOSED-FORM APPROXIMATION OF THE OUTAGE PROBABILITY FOR DISTRIBUTED MIMO SYSTEMS'. IEEE SPAWC: 2009 IEEE 10TH WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS, Perugia, ITALY: 10th IEEE Workshop on Signal Processing Advances in Wireless Communications, pp. 529-533.
  • Heliot F, Fazel S, Hoshyar R, Tafazolli R. (2009) 'RECEIVE KNOWLEDGE ONLY POWER ALLOCATION FOR NONREGENERATIVE COOPERATIVE MIMO COMMUNICATION'. IEEE SPAWC: 2009 IEEE 10TH WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS, Perugia, ITALY: 10th IEEE Workshop on Signal Processing Advances in Wireless Communications, pp. 524-528.
  • Ghader M, Tafazolli R. (2009) 'Efficient Employment of Service Location Protocol in Multi-cluster Networks'. Santander, Spain: ICT-MobileSummit 2009
  • Hoshyar R, Heliot F, Tafazolli R. (2009) 'A Novel Multi-layer Cooperative Decode and Forward Scheme'. IEEE 2009 IEEE VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, Barcelona, SPAIN: 69th IEEE Vehicular Technology Conference, pp. 1248-+.
  • Qi YA, Hoshyar R, Tafazolli R. (2009) 'A New ARQ Protocol for Hybrid DF/CF Relay Scheme'. IEEE 69th IEEE VEHICULAR TECHNOLOGY CONFERENCE, Barcelona, SPAIN: 69th VTC Spring 2009, pp. 1356-1360.
  • Qi YA, Hoshyar R, Tafazolli R. (2009) 'A Novel Quantization Scheme in Compress-and-Forward Relay System'. IEEE IEEE 69th VEHICULAR TECHNOLOGY CONFERENCE, Barcelona, SPAIN: 69th VTC Spring 2009, pp. 1854-1858.
  • Imran A, Tafazolli R. (2009) 'Performance & capacity of mobile broadband WiMax (802.16e) deployed via high altitude platform'. 2009 European Wireless Conference, EW 2009, , pp. 319-323.
  • Fazel MS, Hoshyar R, Tafazolli R. (2009) 'Flexible Amplify and Forward Relaying Protocol with optimized duplexing'. IEEE 2009 IEEE VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, Barcelona, SPAIN: 69th IEEE Vehicular Technology Conference, pp. 3176-3180.
  • Hoshyar R, Tafazolli R. (2009) 'Optimum Decoding of Full Decode and Forward Scheme over Cooperative Relay Channels'. IEEE 2009 IEEE VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, Barcelona, SPAIN: 69th IEEE Vehicular Technology Conference, pp. 1054-1058.
  • Quddus AU, Evans BG, Tafazolli R. (2009) 'Blind adaptive multiuser detection for code division multiple access using Cimmino's reflection method'. Proceedings of 6th International Bhurban Conference on Applied Sciences and Technology, IBCAST-2009, 2, pp. 118-120.
  • Imran A, Tafazolli R. (2009) 'Evaluation and Comparison of Capacities and Costs of Multihop Cellular Networks'. IEEE 2009 INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS (ICT), Marrakech, MOROCCO: 16th International Conference on Telecommunications (ICT), pp. 160-165.
  • Shariat M, Quddus AU, Tafazolli R. (2009) 'Distance-incorporated opportunistic scheduling'. Proceedings of the 2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009, , pp. 675-680.
  • Shariat M, Ul Quddus A, Tafazolli R. (2009) '$publication.get('TITLE')'. IEEE Wireless Communications and Networking Conference, WCNC,
  • Hoshyar R, Tafazolli R. (2009) 'Performance evaluation Of HARQ schemes for Cooperative Regenerative Relaying'. IEEE 2009 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-8, Dresden, GERMANY: IEEE International Conference on Communications (ICC 2009), pp. 3355-3360.
  • Imran A, Shateri M, Tafazolli R. (2009) 'On the Comparison of Performance, Capacity and Economics of Terrestrial Base Station and High Altitude Platform Based Deployment of 4G'. ASSOC COMPUTING MACHINERY PE-WASUN09: PROCEEDINGS OF THE SIXTH ACM INTERNATIONAL SYMPOSIUM ON PERFORMANCE EVALUATION OF WIRELESS AD-HOC, SENSOR, AND UBIQUITOUS NETWORKS, Tenerife, SPAIN: 6th ACM International Symposium on Performance Evaluation of Wireless Ad-Hoc, Sensor, and Ubiquitous Networks, pp. 58-62.
  • Dianati M, Tafazolli R, Shen X, Naik K. (2009) 'A markov model for per-user service of opportunistic scheduling'. Proceedings of the 2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009, , pp. 681-686.
  • Liu H, Ma Y, Tafazolli R. (2009) 'Enhanced linear interpolation schemes for chunk-based OFDMA uplink'. IEEE Vehicular Technology Conference,
  • Salami G, Tafazolli R. (2009) 'On the Performance evaluation of spectrum sharing algorithms between two UMTS operators'. IEEE 2009 INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS (ICT), Marrakech, MOROCCO: 16th International Conference on Telecommunications (ICT), pp. 260-265.
  • Yarmohammad A, Abaii M, Thilakawardana S, Tafazolli R. (2009) 'Inter-operator Dynamic Spectrum Selection in UMTS'. IEEE 2009 IEEE VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, Barcelona, SPAIN: 69th IEEE Vehicular Technology Conference, pp. 504-508.
  • Qi Y, Hoshyar R, Tafazolli R. (2009) 'Efficient hybrid relaying schemes with limited feedback'. Proceedings of the 2009 ACM International Wireless Communications and Mobile Computing Conference, IWCMC 2009, , pp. 754-758.
  • Hoshyar R, Tafazolli R. (2009) 'A Pre-BSC Model for Distributed Turbo Codes'. IEEE 2009 IEEE VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, Barcelona, SPAIN: 69th IEEE Vehicular Technology Conference, pp. 1936-1940.
  • Psaras I, Dianati M, Tafazolli R. (2009) 'Why Rely on Blind AIMDs? (Work in Progress)'. SPRINGER-VERLAG BERLIN NETWORKING 2009, Aachen, GERMANY: 8th International IFIP TC 6 Network Conference 2009 5550, pp. 404-415.
  • Hamadani E, Mostafavi M, Tafazolli R, Rakocevic V. (2009) 'Analysis of IEEE802.11 DCF Parameters on Achievable Throughput in Ad hoc Networks'. IEEE 2009 IEEE 70TH VEHICULAR TECHNOLOGY CONFERENCE FALL, VOLS 1-4, Anchorage, AK: 70th IEEE Vehicular Technology Conference, pp. 465-470.
  • Mach T, Tafazolli R. (2009) 'Mass Mobility Signaling Congestion Avoidance Mechanism Using Randomized Time Distribution of Cell Reselections'. IEEE 2009 INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS (ICT), Marrakech, MOROCCO: 16th International Conference on Telecommunications (ICT), pp. 238-242.
  • Touheed H, Quddus AU, Tafazolli R. (2009) 'Impact of MMSE equalization on adaptive modulation and coding in HSDPA'. Proceedings of 6th International Bhurban Conference on Applied Sciences and Technology, IBCAST-2009, 2, pp. 127-131.
  • Salami G, Tafazolli R. (2009) 'On the Impact of Varying Bandwidth on the Performance of UMTS Spectrum Sharing Algorithm'. UNIV ZAGREB, FAC ELECT ENGN COMP CONTEL 2009: PROCEEDINGS OF THE 10TH INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS, Univ Zagreb, Fac Elect Engn & Comp, Zagreb, CROATIA: 10th International Conference on Telecommunications (ConTEL 2009), pp. 319-324.
  • Yarmohammad A, Tafazolli R. (2009) 'Decentralized inter-radio access network dynamic spectrum selection scheme'. 2009 International Conference on Wireless Communications and Signal Processing, WCSP 2009,
  • Qi Y, Hoshyar R, Tafazolli R. (2009) 'On the Performance of HARQ with Hybrid Relaying Schemes'. IEEE 2009 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-8, Dresden, GERMANY: IEEE International Conference on Communications (ICC 2009), pp. 4357-4362.
  • Salami G, Thilakawardana S, Tafazolli R. (2009) 'The impact of queuing and call setup delays on UMTS spectrum sharing algorithm'. IEEE WTS: 2009 WIRELESS TELECOMMUNICATIONS SYMPOSIUM, Prague, CZECH REPUBLIC: Wireless Telecommunications Symposium 2009, pp. 402-406.
  • Salami G, Thilakawardana S, Tafazolli R. (2009) 'Dynamic spectrum sharing algorithm between two UMTS operators in the UMTS Extension Band'. IEEE 2009 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATION WORKSHOPS, VOLS 1 AND 2, Dresden, GERMANY: IEEE International Conference on Communications (ICC 2009), pp. 338-343.
  • Qi Y, Hoshyar R, Tafazolli R. (2009) 'Efficient ARQ Protocol for Hybrid Relay Schemes with Limited Feedback'. IEEE 2009 IEEE VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, Barcelona, SPAIN: 69th IEEE Vehicular Technology Conference, pp. 1849-1853.
  • Yi N, Ma Y, Tafazolli R. (2008) 'Bit and power loading for OFDM with an amplify-and-forward cooperative relay'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC,

    Abstract

    In this paper, we propose a rate-adaptive bit and power loading approach for the OFDM-based relaying communications. The cooperative relay operates in the half-duplex amplify-and-forward mode. The source and the relay has the separate power constraints. The maximum-ratio combining is employed at -the destination for maximizing the received SNR. Assuming the perfect channel knowledge available at all nodes, the proposed approach is to maximize the throughput (the number of bits/symbol) at the given power constraint and the target link performance. Unlike the water-filling method, the proposed approach does not need the iterative loading process, and can otTer the sub-optimum performance. Computer simulations are used to test the proposed approach for various scenarios with respect to the relay location or the distributed power allocation. © 2008 IEEE.

  • Mirzadeh S, Cruickshank H, Tafazolli R. (2008) 'An efficient key management solution for personal network federations'. Proceedings - The 2nd International Conference on Mobile Ubiquitous Computing, Systems, Services and Technologies, UBICOMM 2008, , pp. 401-406.

    Abstract

    Personal Network Federation (PN-F) aims to provide secure interactions between a subset of devices of different Personal Networks (PN) for achieving a common goal or providing some services in collaborative environments. Security and privacy is one of the major concerns in the development and acceptance of PN-F like collaborative networks and as any other security architecture, the key management is the corner stone of any possible solution. In this paper, we provide security mechanisms and protocols for key exchange and key management in PN Federations and specify how the established keys can be used to secure communications in different layers. © 2008 IEEE.

  • Héliot F, Chut X, Hoshyar R, Tafazolli R. (2008) 'An accurate closed-form approximation of the ergodic capacity over log-normal fading channels'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC,

    Abstract

    The log-normal probability distribution is commonly used in wireless communications to model the shadowing and, more recently, the small-scale fading for indoor ultra-wide-band communications. In this paper, an accurate closed-form approximation of the ergodic capacity over log-normal fading channels is derived. This expression can be easily used to evaluate and compare the ergodic capacity of communication systems operating over log-normal fading channels. © 2008 IEEE.

  • Mirzadeh S, Tafazolli R, Armknecht F, Pallares JJ, Afifi H. (2008) 'CPFP: An efficient key management scheme for large scale personal networks'. IEEE 2008 3RD INTERNATIONAL SYMPOSIUM ON WIRELESS PERVASIVE COMPUTING, VOLS 1-2, Santorini, GREECE: 3rd International Symposium on Wireless Pervasive Computing, pp. 743-747.
  • Zhang Y, Ma Y, Tafazolli R. (2008) 'Improved Coded Cooperation Schemes for Wireless Communications'. IEEE 2008 6th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks and Workshops, Vols 1 and 2, Berlin, GERMANY: 6th International Symposium on Modeling and Optimization in Mobile, Ad-Hoc, and Wireless Networks, pp. 507-512.
  • Hanzo L, Mostafavi SM, Tafazolli R. (2008) 'Connectivity-related properties of mobile nodes obeying the random walk and random waypoint mobility models'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 133-137.
  • Liu H, Ma Y, Tafazolli R. (2008) 'On efficiency gain of joint pilot and data adaptation for OFDM based systems'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC,
  • Zhang Y, Ma Y, Tafazolli R. (2008) 'Modulation-adaptive cooperation schemes for wireless networks'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 1320-1324.
  • Yi N, Ma Y, Tafazolli R. (2008) 'Rate-adaptive bit and power loading for OFDM based DF relaying'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 1340-1344.
  • Yi N, Ma Y, Tafazolli R. (2008) 'Doubly differential communication assisted with cooperative relay'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 644-647.
  • Hoshyar R, Tafazolli R. (2008) 'Achievable full decode and forward rates for cooperative MIMO BICM systems'. IEEE IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, Cannes, France: 19th PIMRC 2008
  • Hoshyar R, Tafazolli R. (2008) 'Soft decode and forward of MQAM modulations for cooperative relay channels'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 639-643.
  • Movahedian M, Ma Y, Tafazolli R. (2008) 'Iterative carrier frequency offset estimation and compensation for OFDMA uplink'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC,
  • Movahedian M, Ma Y, Tafazolli R. (2008) 'An MUI resilient approach for blind CFO estimation in OFDMA uplink'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC,
  • Quddus AU, Yang X, Tafazolli R. (2008) 'Link-level analysis of downlink handover regions in UMTS'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 2527-2531.
  • Shariat M, Quddus AU, Tafazolli R. (2008) 'On the efficiency of interference coordination schemes in emerging cellular wireless networks'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC,

    Abstract

    In this paper, the efficiencies of different interference coordination schemes are evaluated for emerging wireless networks and the possible impact on intra-cell scheduling is studied through extensive simulations. The results show that pure fractional frequency reuse can provide similar improvement in the cell-edge throughput compared to power coordinated counterpart at a less cost in terms of overall throughput. Moreover, it can provide fairer distribution of throughput in both central as well as cell-edge areas. However, this scheme can not mange asymmetrical changes in the distribution of users across different cells in the entire system. As a result, a power coordination mechanism would be still necessary on top of such flexible frequency reuse schemes. © 2008 IEEE.

  • Salami G, Quddus AU, Thilakawardana D, Tafazolli R. (2008) 'Nonpool based spectrum sharing for two UMTS operators in the UMTS extension band'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC,

    Abstract

    This paper investigates spectrum sharing (in the form of code sharing) between two Universal Mobile Telecommunication System (UMTS) operators in the UMTS extension band (2500-2690MHz) with equal and unequal number of proprietary carriers, respectively. The paper proposes a Dynamic Spectrum Allocation (DSA) algorithm to address the problem of spectrum sharing between two operators on a non-pool basis. It also investigates the impact of Adjacent Channel Interference (ACI) on the spectrum sharing gain. Additionally, an architecture that enables spectrum sharing to take place between two or more UMTS operators is presented. The simulated performance of the proposed DSA algorithm shows that under peak-hour loading, up to 32% increase in capacity can be obtained when compared to currently used Fixed Spectrum Allocation (FSA). © 2008 IEEE.

  • Hoshyar R, Tafazolli R. (2008) 'BER performance analysis of a cooperative BICM system based on post-BSC model'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC,
  • Dianati M, Tafazolli R. (2008) 'Opportunistic scheduling over wireless fading channels without explicit feedback'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 1871-1875.
  • Wathan FP, Hoshyar R, Tafazolli R. (2008) 'PERFORMANCE ANALYSIS OF GROUPED CHIP-LEVEL ITERATED MULTIUSER DETECTION FOR OVERLOADED CDMA SYSTEMS'. IEEE 2008 IEEE 9TH WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS, VOLS 1 AND 2, Recife, BRAZIL: 9th IEEE Workshop on Signal Processing Advances in Wireless Communications, pp. 131-135.
  • Qi Y, Hoshyar R, Tafazolli R. (2008) 'Performance evaluation of soft decode-and-forward in fading relay channels'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 1286-1290.
  • Touheed H, Quddus AU, Tafazolli R. (2008) 'An improved link adaptation scheme for High Speed Downlink Packet Access'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 2051-2055.
  • Touheed H, Quddus AU, Tafazolli R. (2008) 'Predictive CQI reporting for HSDPA'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC,
  • Yi N, Ma Y, Tafazolli R. (2008) 'Multi-tone transmissions over two-user cognitive radio channel with weak interference'. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC,
  • Liu H, Ma Y, Tafazolli R. (2008) 'Optimum pilot placement for chunk-based OFDMA uplink: Time direction scenario'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 2547-2551.
  • Jung J, Abaii M, Tafazolli R. (2008) 'Load Matrix optimization in mobile cellular networks'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 2016-2020.
  • Wang M, Georgiades M, Tafazolli R. (2008) 'Signalling cost evaluation of mobility management schemes for different core network architectural arrangements in 3GPP LTE/SAE'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 2253-2258.
  • Hamid A, Hoshyar R, Tafazolli R. (2008) 'Joint rate and power adaptation for MC-CDMA over tempo-spectral domain'. IEEE WCNC 2008: IEEE WIRELESS COMMUNICATIONS & NETWORKING CONFERENCE, VOLS 1-7, Las Vegas, NV: IEEE Wireless Communications and Networking Conference, pp. 969-973.
  • Mirzadeh S, Tafazolli R, Pallares JJ, Armknecht F, Afifi H. (2008) 'CPFP: An efficient key management scheme for large scale personal networks'. 3rd International Symposium on Wireless Pervasive Computing, ISWPC 2008, Proceedings, , pp. 744-748.

    Abstract

    This paper provides an efficient key management scheme for large scale personal networks (PN) and introduces the Certified PN Formation Protocol (CPFP) based on a personal public key infrastructure (personal PKI) concept and Elliptic Curve Cryptography (ECC) techniques. © 2008 IEEE.

  • Sand S, Mensing C, Ma Y, Tafazolli R, Yin X, Figueiras J, Nielsen J, Fleury BH. (2008) 'Hybrid data fusion and cooperative schemes for wireless positioning'. IEEE Vehicular Technology Conference,
  • Qi Y, Hoshyar R, Tafazolli R. (2008) 'Soft multilevel Slepian-Wolf decoding in systems using Turbo joint decoding and decompressing'. IEEE 2008 IEEE 67TH VEHICULAR TECHNOLOGY CONFERENCE-SPRING, VOLS 1-7, Marina Bay, SINGAPORE: 67th IEEE Vehicular Technology Conference, pp. 1514-1518.
  • Ghader M, Tafazolli R. (2007) 'Enhanced Service Location Protocol in Personal Network'. Jaipur, India: WPMC’07
  • Schott W, Gluhak A, Presser M, Hunkeler U, Tafazolli R. (2007) 'e-SENSE protocol stack architecture for wireless sensor networks'. IEEE 2007 PROCEEDINGS OF THE 16TH IST MOBILE AND WIRELESS COMMUNICATIONS, VOLS 1-3, Budapest, HUNGARY: 16th IST Mobile and Wireless Communications, pp. 464-468.
  • Liu H, Ma Y, Tafazolli R. (2007) 'Sub-optimum pilot placement for chunk-based OFDMA uplink: Consecutive chunks scenario'. IEEE 2007 IEEE 18TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-9, Athens, GREECE: 18th IEEE International Symposium on Personal, Indoor and Mobile Radio Communication, pp. 1925-1929.
  • Hanzo L, Tafazolli R. (2007) 'Quality of Service routing and admission control for mobile ad-hoc networks with a contention-based MAC layer'. IEEE 2006 IEEE International Conference on Mobile Adhoc and Sensor Systems, Vols 1 and 2, Vancouver, CANADA: IEEE International Conference on Mobile Adhoc and Sensor Systems, pp. 451-454.
  • Li Z, Akhtar N, Tafazolli R. (2007) 'Seamless IP multimedia service continuity support in inter-worked UMTS and WLAN'. IEEE 2007 IEEE 18TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-9, Athens, GREECE: 18th IEEE International Symposium on Personal, Indoor and Mobile Radio Communication, pp. 1478-1482.
  • Grandblaise D, Moessner K, Vivier G, Tafazolli R. (2007) 'Credit token based rental protocol for dynamic channel allocation'. 1st International Conference on Cognitive Radio Oriented Wireless Networks and Communications 2006, CROWNCOM,

    Abstract

    This paper describes a distributed, cooperative and real time rental protocol for DCA operations in a multi system and mult) cell context for OFDMA systems. A credit token based rental protocol using auctioning Is proposed in support of dynamic spectrum sharing between cells. The proposed scheme can be tuned adaptively as a function of the context by specifying the credit tokens usage in the radio etiquette. The application of the rental protocol is illustrated with an ascending bid auctioning. The paper also describes two approaches for BS-BS communications in support of the rental protocol. Finally, it is described how the proposed mechanisms contribute to the current approaches followed in the IEEE 802.16h and IEEE 802.22 standards efforts addressing cognitive radio, © 2006 IEEE.

  • Liu H, Ma Y, Tafazolli R. (2007) 'Optimum pilot placement for chunk-based OFDMA uplink: Single chunk scenario'. IEEE 2007 IEEE 66TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, Baltimore, MD: 66th IEEE Vehicular Technology Conference, pp. 2194-2198.
  • Zhang Y, Ma Y, Tafazolli R. (2007) 'Tighter bounds of symbol error probability for amplify-and-forward cooperative protocol over rayleigh fading channels'. IEEE 2007 IEEE 18TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-9, Athens, GREECE: 18th IEEE International Symposium on Personal, Indoor and Mobile Radio Communication, pp. 1920-1924.
  • Thilakawardana S, Acar G, Hale B, Tafazolli R. (2007) 'Impact of status retry timer values on MFTP performance over bgan satellite multicast'. IEEE 2007 IEEE 18TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-9, Athens, GREECE: 18th IEEE International Symposium on Personal, Indoor and Mobile Radio Communication, pp. 4089-4094.
  • Hanzo L, Tafazolli R. (2007) 'Throughput assurances through admission control for multi-hop MANETs'. IEEE 2007 IEEE 18TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-9, Athens, GREECE: 18th IEEE International Symposium on Personal, Indoor and Mobile Radio Communication, pp. 1945-1949.
  • Wathan FP, Hoshyar R, Tafazolli R. (2007) 'Iterated SISO MUD for synchronous uncoded CDMA systems over AWGN channel: Performance evaluation in overloaded condition'. IEEE 2007 INTERNATIONAL SYMPOSIUM ON COMMUNICATIONS AND INFORMATION TECHNOLOGIES, VOLS 1-3, Sydney, AUSTRALIA: International Symposium on Communication and Information Technology, pp. 397-402.
  • Grandblaise D, Moessner K, Vivier G, Tafazolli R. (2006) 'Rental protocol for automated spectrum sharing negotiation between base stations'. FACHVERLAG SCHIELE SCHON FREQUENZ, Karlsruhe, GERMANY: 4th Karlsruhe Workshop on Software Radios 60 (9-10), pp. 162-166.
  • Ghader M, Olsen RL, Prasad V, Jacobsson M, Sanchez L, Lanza J, Louati W, Girod-Genet M, Zeghlache D, Tafazolli R. (2006) 'Service Discovery in Personal Networks; design, implementation and analysis'. Mykonos, Greece: 15th IST Mobile and Wireless communications Summit
  • Qi Y, Hoshyar R, Tafazolli R. (2006) 'Capacity of Intelligent Quadrifiliar Helix Antenna (IQHA) based MIMO system'. IEEE 2006 IEEE International Workshop on Antenna Technology: Small Antennas and Novel Metamaterials (IWAT), White Plains, NY: 2nd IEEE International Workshop on Antenna Technology, pp. 365-368.
  • Nourizadeh H, Nourizadeh S, Tafazolli R. (2006) 'Performance evaluation of Cellular Networks with Mobile and Fixed Relay Station'. IEEE 2006 IEEE 64TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6, Montreal, CANADA: 64th IEEE Vehicular Technology Conference, pp. 2434-2438.
  • Acar G, Thilakawardana S, Tafazolli R, Evans B. (2006) 'Performance of Multicast File Transfer Protocol (MFTP) over geostationary satellite systems with DAMA uplinks'. Collection of Technical Papers - 24th AIAA International Communications Satellite Systems Conference, ICSSC, 1, pp. 61-74.
  • Nourizadeh H, Nourizadeh S, Tafazolli R. (2006) 'Impact of the Inter-relay Handoff on the Relaying System Performance'. IEEE 2006 IEEE 64TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6, Montreal, CANADA: 64th IEEE Vehicular Technology Conference, pp. 2529-2533.
  • Hamid A, Hoshyar R, Tafazolli R. (2006) 'Band Based Dynamic Link Adaptation for MC-CDMA Radio Interface'. IEEE 2006 IEEE 64TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6, Montreal, CANADA: 64th IEEE Vehicular Technology Conference, pp. 791-795.
  • Presser M, Gluhak A, Babb D, Tafazolli R, Herault L. (2006) 'E-SENSE - Capturing ambient intelligence for mobile communications through wireless sensor networks'. INSTICC-INST SYST TECHNOLOGIES INFORMATION CONTROL & COMMUNICATION WINSYS 2006: Proceedings of the International Conference on Wireless Information Networks and Systems, Setubal Coll Business Adm, Setubal, PORTUGAL: International Conference on Wireless Information Networks and Systems, pp. 341-346.
  • Navaratnam P, Akhtar N, Tafazolli R. (2006) 'On the performance of DCCP in wireless mesh networks'. MobiWAC 2006 - Proceedings of the 2006 ACM International Workshop on Mobility Management and Wireless Access, 2006, pp. 144-147.
  • Georgiades M, Akhtar N, Ghader M, Li Z, Gultchev S, Tafazolli R. (2005) 'Surrey's Next Generation Wireless Network Testbed'. Marrakech, Morocco: 7th IEEE International Conference on Mobile and Wireless Communications Networks
  • Mirzadeh S, Tafazolli R. (2005) 'Secure Service Discovery for Personal Networks'. Shiraz, Iran: International Symposium on Telecommunications 2005 (IST2005)
  • Ghader M, Olsen RL, Giro-Genet M, Tafazolli R. (2005) 'Service Management Platform for Personal Networks'. Dresden, Germany: 14th IST Mobile and Wireless communications Summit
  • Tang SY, Thilakawardana S, Tafazolli R, Qian Y. (2005) 'Performance analysis of predictive scalable resource allocation for integrated wireless networks'. IEEE 2005 INTERNATIONAL CONFERENCE ON WIRELESS NETWORKS, COMMUNICATIONS AND MOBILE COMPUTING, VOLS 1 AND 2, Maui, HI: International Conference on Wireless Networks, Communications and Mobile Computing, pp. 745-750.
  • Ma Y, Tafazolli R. (2005) 'Exploiting hidden pilots for carrier frequency offset estimation for generalized MC-CDMA systems'. IEEE 2005 IEEE/SP 13th Workshop on Statistical Signal Processing (SSP), Vols 1 and 2, Bordeaux, FRANCE: 13th IEEE Workshop on Statistical Signal Processing, pp. 1237-1241.
  • Sali A, Widiawan A, Thilakawardana S, Tafazolli R, Evans BG. (2005) 'Cross-layer design approach for multicast scheduling over satellite networks'. IEEE 2nd International Symposium on Wireless Communications Systems 2005 (ISWCS 2005), Univ Siena, Siena, ITALY: 2nd International Symposium on Wireless Communications Systems (ISWCS 2005), pp. 701-705.
  • Ghader M, Tafazolli R. (2004) 'Performance of Service Discovery Protocols in Personal Networks'. Shanghai, China: IST MAGNET Workshop, Visions and Beyond
  • Ghader M, Prasad N, Olsen RL, Mirzadeh S, Tafazolli R. (2004) 'Secure Resource and Service Discovery in Personal Networks Wireless'. Toronto, Canada: World Research Forum Meeting #12
  • Ghader M, Moessner K, Tafazolli R. (2004) 'Service Discovery and Provision Protocols for Wireless Networks'. Lyon, France: 13th IST Mobile & Wireless Communications Summit

Books

  • Forum WWR. (2006) Technologies for the wireless future. John Wiley & Sons

Book chapters

  • Han C, Muhaidat S, Abualhaol I, Dianati M, Tafazolli R. (2013) 'Intrusion Detection in Vehicular Ad-Hoc Networks on Lower Layers'. in (ed.) Security, Privacy, Trust, and Resource Management in Mobile and Wireless Communications IGI Global Article number 8
  • Hanzo L, Tafazolli R. (2008) 'Mobile Ad Hoc Networks: Challenges and Solutions for Providing Quality of Service Assurances'. in Kyriazakos S, Soldatos I, Karetsos G (eds.) 4g Mobile and Wireless Communications Technologies River Publishers

Patents

  • Hoseinitabatabaei SA, barnaghi P, tafazolli R, wang C. Method and apparatus for scalable data discovery in IoT systems.

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