Boris Oklander (Imperial College London)
Wednesday, 27.11.2013, 11:30
Admission control is a classical topic in communications, but cognition as a means to enhance the performance of users and the network is relatively new. Cognitive Users’ (CU) can achieve better performance based on smart access to resources such as power and spectrum. However, adaptation to dynamically changing conditions of communication channels is a challenge for CUs. Acting as a secondary user (SU), a CU cedes priority to ongoing transmissions of PUs and accesses a channel only after sensing and estimating that it is not used by PUs. Thus efficient CUs will trade between competing requirements of sensing, transmitting and interference avoidance, subject to power limitations. This of course requires understanding the interdependence of the various processes involved and their impact on performance.
This talk will present a CU's queueing model with walking type server (or vacations). The analysis yields explicit expressions for the first two moments of CU packet service time, and provides an optimization of throughput, delay, interference, energy efficiency and QoS. As opposed to the conventional server vacations that prolong the effective service time, here they reduce the service and response time. Additionally, modifications to CU's service process are introduced, showing the ability of CU to improve its performance by adapting to the communications environment.
Dr. Boris Oklander received B.Sc., M.Sc. and Ph.D. degrees in Electrical Engineering from the Technion in 2001, 2008 and 2013 respectively. Currently he is a research associate at Intelligent Systems and Networks Group, Imperial College London. His research interests are in modeling and performance evaluation of communications networks.