Abstract : Enhanced-power saving-semi persistent scheduler (E-PS-SPS) for downlink voice over LTE (VoLTE) traffic was proposed to reduce the energy consumption of the LTE eNodeB. Further, it was established that E-PS-SPS outperforms traditional SPS (T-SPS) both in terms of energy consumption and capacity (maximum number of simultaneous calls it can handle). However, in order to establish the superiority of E-PS-SPS, the analysis and comparison was done with two strong simplifying assumptions; (i) same downlink mean signal-to-noise ratio (SNR) for all the VoLTE users even though the mean SNRs are independently and identically distributed (i.i.d.) and (ii) same instantaneous downlink channel gains on different physical resource blocks (PRBs) resulting in same instantaneous SNR on all allocated PRBs for a user in a packet transmission attempt, even though channel gains on different PRBs are i.i.d.. In this paper, we carry out a more general analysis of E-PS-SPS in a more realistic scenario by removing these two strong assumptions and derive a closed-form expression for its capacity and achievable success rate. The analytical expressions are validated using Monte Carlo simulations. We then use these expressions to show how the performance of E-PS-SPS can be maximized for a desired success rate. Finally, we also show through extensive simulations that the capacity of E-PS-SPS is same as T-SPS in the realistic scenario which we consider in the work. However, T-SPS has a marginally better success rate than E-PS-SPS which can be overlooked considering the significant energy saving that E-PS-SPS can offer.
Index terms : Capacity, enhanced power saving semi persistent scheduler, optimal performance, success rate, VoLTE.