Performance Analysis of Large CDMA Random Access Systems with Retransmission Diversity over Fading Channels

The random access systems, with retransmission diversity (RD) employment, over large random spreading code division multiple access (CDMA) channel subject to fading is investigated, under the assumption of infinite number of users and infinite spreading gain with their ratio converging to a constant. The low bound of the signal to interference and noise ratio (SINR) is shown to converge almost surely to a constant. The throughput, spectrum efficiency and energy efficiency in the dominating systems are obtained. The analytical results are confirmed by simulations. We find that in high traffic loads the throughput with fading is higher than that without. When the energy efficiency increases, the spectrum efficiency tends to two contrary values due to SNR increases or decreases. For the ordinary stable systems, the stability region is shown to shrink as the traffic increases and enlarge with RD employment.

• Type: Journal
• Year: 2010
• Where: ITIIS
• Authors: Kai Yu, Yi Sun, Pingzhi Fan, Xianfu Lei, Lei Shu
• Keywords: Code Division Multiple Access, Energy Efficiency, ITIIS 2010, Random Access Systems