Power control in WCDMA networks: a queue-based approach

In modern wireless communication systems, power control plays afundamental role for efficient resource utilization.In such systems, in fact, many users transmit over the same radiochannel using the same frequency band and time slots so that thesignal of an individual user becomes interference for the other users.Hence the transmission power levels need to be smartlymanipulated so as to achieve an adequate quality of service foras many users as possible and, thus, an efficient networkutilization.Conventional power control algorithms adopt the Signal-to-Interference-plus-Noise Ratio (SINR) as controlledvariable and neglect the important effects of the manipulated controlvariables (transmission powers) and of the retransmission mechanism on the queueing dynamics.In this paper, we pursue a different queue-based approachwhich takes into account the queuing dynamics and adopts thequeue size as controlled variable.In this framework, the power control problem is formulated as anoptimal control problem with a criterion trading off high performance(low queue sizes) vs. low costs (low transmision powers).In particular, a novel queue-based power control algorithm withlow on-line computational burden is proposed and its performance isevaluated via simulation experiments. The simulation results exhibitan improved behavior of the proposed queue-based algorithm compared to conventionalSINR-based algorithms.