Voice and data transmissions with a PRMA-like protocol in high propagation delay cellular systems

Abstract

Future mobile communication systems will require new medium access control protocols to attain an efficient multiplexing of different traffic sources while guaranteeing their requirements on quality of service. This paper investigates the performance of a modified packet reservation multiple access (PRMA) protocol, called PRMA with hindering states (PRMA-HS), for supporting voice and data transmissions in mobile cellular systems with high propagation delays. A scenario based on low earth orbit mobile satellite systems (LEO-MSSs) has been considered, but the analytical approach is general. We have obtained that PRMA-HS achieves a high capacity of voice sources in LEO-MSSs also in the presence of data traffic. A performance analysis has been carried out showing good agreement with simulation results. Finally, the PRMA-HS performance has been evaluated in the presence of different data traffic sources

Sleep-enabled roadside units for motorway vehicular networks

“…32 ms [11]), which implies that the individual packets delay was substantially higher than the already out of bound average packet delay. Hence, the average packet delay at the CHs needs to be minimised in order to maintain the end-to-end maximum individual packet delay bound for audioconferencing [11], one of the necessary and most demanding bounds. Since the RSUs have large buffer capacity, the packet blocking probability is negligible at the RSU.…”

“…This mechanism was called random sleep cycles. The same random sleep cycles were utilised in [10], which resulted in an unacceptable average packet delay for audio-conferencing applications [11]. For ease of reference, the random sleep cycles introduced in [9], [10] are termed sleep cycles type-I in this paper.…”

“…The resultant packet stream at the output of the CHs is the input to the RSU. Since we aim to introduce energy savings at the RSUs while keeping the end-to-end QoS within acceptable bounds, any sleep strategy at the RSU will be meaningless as the maximum individual packet delay at the CH(s) was already unacceptable [10] for audio-conferencing [11]. Therefore, we first introduce sleep cycles type-II at the CHs, which improves the QoS, leading to the study of various types of sleep cycles at the RSU.…”

“…Therefore, we first introduce sleep cycles type-II at the CHs, which improves the QoS, leading to the study of various types of sleep cycles at the RSU. Energy saving is maximised at the RSU while maintaining stringent bounds on the end-to-end QoS (packet blocking probability within 5% [9] and maximum individual packet delay within 32 ms [11]). Our approach enables us to evaluate the performance of the proposed sleep cycles under very stringent operating bounds (required for audio conferencing), though modern compression and codes allow more leniency on packet delay [21].…”

“…The RSU remains in such mode for the entire time duration (randomly generated with a certain mean value) even if packets are waiting to be served, thus degrading the system performance. Similarly a random sleep strategy was utilised in [10], which resulted in an unacceptable average packet delay [10] for audio-conferencing applications [11].…”