Channel-Aware Random Access in the Presence of Channel Estimation Errors

In this work, we consider the random access of nodes adapting their transmission probability based on the local channel state information (CSI) in a decentralized manner, which is called CARA. The CSI is not directly available to each node but estimated with some errors in our scenario. Thus, the impact of imperfect CSI on the performance of CARA is our main concern. Specifically, an exact stability analysis is carried out when a pair of bursty sources are competing for a common receiver and, thereby, have interdependent services. The analysis also takes into account the compound effects of the multipacket reception (MPR) capability at the receiver. The contributions in this paper are twofold: first, we obtain the exact stability region of CARA in the presence of channel estimation errors; such an assessment is necessary as the errors in channel estimation are inevitable in the practical situation. Secondly, we compare the performance of CARA to that achieved by the class of stationary scheduling policies that make decisions in a centralized manner based on the CSI feedback. It is shown that the stability region of CARA is not necessarily a subset of that of centralized schedulers as the MPR capability improves.Comment: The material in this paper was presented in part at the IEEE International Symposium on Information Theory, Cambridge, MA, USA, July 201

On the stability and delay of channel-aware slotted ALOHA with imperfect CSI

[[abstract]]© 2008 Institute of Electrical and Electronics Engineers-In this work, we study the effect of imperfect channel-state information (CSI) on the stability and delay of a two-user channel-aware slotted ALOHA system. We assume that the channel is quantized into two states and channel estimation error may occur between channel states. By taking into account the estimation error, we derive the optimal transmission control function that adjusts the users' transmission probabilities based on the estimated channel state. To evaluate the performance, we derive the stability region and average delay of the system and show the loss in performance due to channel estimation errors.[[fileno]]2030137030022[[department]]電機工程學