Cellular Cdma Capacity Improvement Using Ad Hoc Relaying

In this paper we consider the capacity of a cellular CDMA system when there is out-of-band ad hoc traffic relaying. In the system studied, the mobile stations (MSs) are dual-mode, having both ad hoc and cellular CDMA radios. An active MS is free to choose any available relay station (RS) within its ad hoc radio coverage area for communication with the CDMA base station (BS). A relay station selection protocol, referred to as ad hoc relaying with best link gain (ARLG), is proposed which dynamically tracks the CDMA link quality when making this determination. An analytic model is used to compute the effects on uplink and downlink CDMA capacities when using the proposed protocol. The results show that very significant capacity improvements are possible by using this algorithm. Multihop relaying of this kind can be used to improve the performance of a cellular system, or to improve the performance in CDMA hotspot cells.