Multi-user spatial diversity in a shadow-fading environment

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 region. 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. In this paper we study the scheme of "multi-user spatial diversity" as a new method of diversity to combat the undesired shadow-fade situation. We study the case where one or several mobile stations (MSs) relay the signal between the source and the DMS, in a shadow-fading environment. We derive a formula 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.