Outage Analysis of a Multi-User Spatial Diversity System in a Shadow-Fade Propagating Channel

In a wireless network, communication between a source and a destination mobile station (DMS) fails to establish if the source or the DMS is located inside a deep shadow-fading propagating channel. In this situation, intermediate mobile stations may be used to relay the signal between the two nodes. In a cellular system the source is a base station (BS) and the DMS is a weak mobile station (MS) while in an ad-hoc network, the source and the DMS are two nodes of the network. This paper presents the scheme of “multi-user spatial diversity” as a method of diversity to combat the undesired shadow-fade channel behavior. A model is presented for the case where one or several mobile stations (MSs) relay the signal between the source and the DMS, in a shadow-fading environment. A formula is derived for the average outage probability of the received signal-to-noise ratio at the DMS, when M intermediate MSs relay the signal from the source to the DMS according to a particular protocol. The outage probability improves as the number of the relays increases.