Radio Access System Optimisation

The Radio Access System (RAS) optimisation focuses on different aspects of system‐level efficiency in emerging wireless networks such as Femtocell Networks, Vehicular Networks, and Self-organising Networks. 

This includes different areas like:

  • Radio Resource Scheduling and MAC (Distributed and centralised)
  • Energy Efficiency and Capacity Optimisation
  • Routing and Load Balancing
  • Interference Management
  • Self‐organising Radio Access

Radio resource scheduling and medium access control

In Radio Resource Scheduling and Medium Access Control (MAC), the main focus is on efficient utilisation of scarce wireless resources considering some important factors like:

  • Throughput Efficiency
  • Fairness
  • Quality of Service (QoS).

This problem can be mathematically modelled as maximising the profit (e.g. Throughput), minimising the cost (e.g. power) subject to some additional constrains, and providing the required QoS (e.g. constrained end-to-end delay).

Energy efficiency and capacity optimisation

In Energy Efficiency, we try to revisit the RRM problem to incorporate the effect of energy consumption. This is quite important from environmental perspective to reduce the carbon emissions, as well as from business perspective to provide higher business efficiency. This problem introduces new challenges to redesign RRM algorithms. Again the problem can be mathematically modelled based on profit or cost. Here, the profit depends on both throughput and energy consumption and can be modelled in Bits/ Joule where new trade-offs are identified.

Routing and load balancing

Routing or forwarding process adds a new dimension to the already established RRM problem. Here, the major focus will be on the effect of routing algorithms on overall efficiency of the system. The aim is to minimise the overhead and the delay introduced by the protocol. Such routing protocols can potentially incorporate cross-layer information from:

  • Physical
  • MAC
  • Traffic Information to enhance the efficiency of routing protocols.

Interference management

Cellular systems are inherently interference-limited. The interference factor originates from the reuse of spectrum (resources) across different links (in different cells) in the network. Although orthogonalisation of radio resources across different cells can help to mitigate the problem, this leads to a lower level of spectral efficiency. As a result, inevitably more dynamic methods are required to alleviate the resulting interference. In general interference mitigation techniques can be categorised to

  • Randomisation
  • Coordination and
  • Cancellation.

where all techniques can be applied in different time scales, i.e. static, semi static or dynamic.

Self‐organising radio access

Self-organisation by definition is to organise the local behaviour(s) in the system to achieve a certain global objective without utilising central control entities. According to this definition, some important attributes can be identified for self-organising protocols:

  • High levels of scalability as such protocols are applied to large networks,
  • Low levels of complexity to ensure the feasibility even in dynamic networks, and
  • Finally, adaptability to various changes and dynamism in wireless environment.
Self organisation graph

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