- タイトル
- Stability and capacity of large Aloha systems with retransmission gain and Poisson new arrival
- 著者
- Y.Sun
- 出典
- Proc. CISS,
Baltimore, MD,
2003/03.
- キーワード
- stability, spread ALOHA, slotted ALOHA, Poisson arrival, throughput, asymptotic property, capture effect, DS-CDMA
- 概要
- We consider large Aloha systems in which the mean arrival rate and channel bandwidth tend to infinity with their ratio kept a constant. IN such large Aloha systems the channel uncertainty is captured by a notion of effective interference and thus the packet success probability depends only on the mean composite arrival per dimension and is independent of the number of users that transmit packets in a particular slot. It is shown that with Poisson new arrival the numbers of backlogged packets, transmitted packets, and successful packets in each slot in the limiting system all are Poisson distributed. Moreover, their means - the backlog, offered load, and steady throughput per dimension can be obtained by a deterministic iterative equation. The stability and the capacity are analyzed. To consider guaranteed QoS transmission- and delay-constrained capacities are then defined. All MAC performance measures are obtained in closed forms instead of bounds. It is shown that the stability and capacity are independent of packet transmission probability though the backlog and packet delay depend on the transmission probability. The results are applied to large CDMA Aloha systems that employ random independent equiprobable spreading sequences. Numerical examples for the large CDMA systems employing MF, decorrelator, and MMSE detectors are presented. It is shown that exploitation of retransmission diversity can substantially increase capacity of large CDMA Aloha systems.
- 分類
- [MAC]多元接続安定性：ALOHA (No.4458)