Analytical evaluation of signalling cost on power saving mechanism in mobile networks

Battery lifetime is one of the most important requirements for the user equipment (UE). UE battery gets drained due to the excess processing of signalling messages. Exploiting the bursty nature of data traffic, discontinuous reception (DRX) mechanism is emerging as most accepted power saving mechanism across the wireless standards. The analytical evaluation of performance of DRX considers power saving factor as a ratio of idle time to total time; therefore, neglecting the signalling which occurs during the state transitions. In the purview of new traffic models, with low reading time and high session transitions, power saving is not fully defined without considering the involved signalling cost. This paper presents an analytical model, wherein close form expression for power saving factor, signalling during state transitions and wake-up time as a parameter to evaluate signalling cost involved during power saving mechanism, is derived. A new modified power saving factor is proposed which captures the signalling cost with various system configuration parameters viz. inactivity timer, number of short cycle, on duration, and delay in the reconnection.