Performance degradation due to the access timing delay on CDMA unslotted ALOHA with channel load sensing

Throughput analysis of CDMA unslotted ALOHA with channel load sensing protocol (CLSP) is presented in consideration of the effect of the access timing delay. The access timing delay is defined as the sum of the process time and the propagation time for the packet access control. As CLSP is the scheme used to control packet generation due to the channel state information from the hub station, the effect of the access timing delay is significant. In our analysis, we extend a continuous-time Markov chain model and queueing systems. As a result, we found degradations of the throughput performance due to the access timing delay. For the value of the CLSP threshold, we show that it is smaller than the case without the access timing delay in order to achieve satisfactory throughput. Furthermore, for a large access timing delay, the CLSP makes no sense and the throughput is worse than the system without employing CLSP