Improved energy-saving medium access control schemes for best-effort and QoS-enabled point-controlled wireless networks

Energy efficiency is an important design consideration due to the limited battery life of mobile and handportable terminals.

PCSAR, a new power-saving medium access control (MAC) protocol for centralised control wireless networks is presented in this work. The steady state performance of PCSAR was compared with IEEE 802.11b infrastructure power saving mode (PCF-PS) using discrete event simulation. Under error-free conditions and a range of channel loading values, the simulated results demonstrated a significant improvement in energy saving when using PCSAR, with an average saving of 25 per cent, rising to 40 per cent at saturated loads.

PCSAR was compared with PCF-PS for both uncorrelated and time-correlated channel models. Simulations were performed for two different scenarios: increasing values of frame error rate (FER) and an increasing number of time-correlated error stations in the network. Depending upon the load and the FER or number of time-correlated error stations, PCSAR was found to be up to 31 per cent more energy efficient than PCF-PS.

PCSAR was also modified to suit a quality of service enabled MAC such as IEEE 802.11e. The performance of this version, PCSARe, was compared with the non-APSD and S-APSD IEEE 802.11e infrastructure power saving mechanisms. Overall, PCSARe was 39 per cent more energy efficient than the IEEE 802.11e best-effort non-APSD stations.

Future work in this area (wireless MAC protocols) will most likely focus on cross-layer optimisation for smart antenna and MIMO based systems.

Funding: Association of Commonwealth Universities Commonwealth Scholarship (PhD)

People:
GA Safdar
WG Scanlon (PI)