Effects of the Access Timing Delay on CDMA Unslotted ALOHA with Channel Load Sensing

Takeshi SATO  Hiraku OKADA  Takaya YAMAZATO  Masaaki KATAYAMA  Akira OGAWA  

IEICE TRANSACTIONS on Communications   Vol.E79-B    No.9    pp.1339-1345
Publication Date: 1996/09/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Personal Communications)
Category: CDMA and multiple access technologies
CDMA ALOHA,  CLSP,  access timing delay,  

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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 to control packet generation by 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 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, CLSP makes no sense and the throughput is worse than the system without employing CLSP.