Reverse-link power allocation in two-hop multimedia CDMA networks

摘要

Recently there has been significant interest in augmenting the cellular networks with the multihop capability to obtain better high data rate performance in the context of enhanced-3G and beyond-3G networks. This paper deals with the power allocation strategies in the reverse-link of two-hop multimedia CDMA networks. In this envisioned network, the WTs (wireless terminals) which cannot establish a direct link with the BS (at the required rates) seek the assistance of those WTs which can; in other words, whenever needed, some WTs are used as relayers for some other WTs (relayees) if this is possible. In a two-hop link, the first hop (relayee to relayer) uses the unlicensed band and the second hop (relayer to BS) uses the cellular band. This arrangement not only guarantees that no additional expensive cellular spectrum will be used to facilitate a two-hop link, but it also guarantees that if anything goes wrong in the first hop, this will not affect the performance of the WTs which directly communicate with the BS in the cellular band. The performance of any CDMA network depends on the implementation of a good power allocation and control scheme. The optimum power allocation and control in the reverse link of the conventional single-hop CDMA networks is well known. The main contribution of this paper is the development of a good power allocation scheme (which is tied to the proper selection of relayers) in the first hop of the two-hop reverse-link of the envisioned CDMA network. It is worth emphasizing that the nature of the reverse-link power allocation problem is very different in the many one-to-one links (or possibly numerous several-to-one links) which collectively constitute the first hop of the two-hop CDMA network under consideration, in comparison to that in the single many-to-one link in the reverse link of a conventional single-hop CDMA network. The simulation results show that the two-hop relaying, facilitated with the developed novel power allocation scheme, yields considerable enhancements in the CDMA cell capacity, coverage, and throughput.