Combating shadowing effects for systems with transmitter diversity by using collaboration among mobile users

In the current wireless cellular systems, each mobile station (MS) independently communicates with a base station (BS). In order to improve the connectivity of an MS (called a weak mobile station, WMS) that is in a deep shadow-faded state, this paper proposes a collaboration scheme among the MSs. In the proposed approach, an MS, which is in standby mode, relays signals between a nearby WMS and the BS. The paper provides analytical and simulation results for the outage probabilities of a non-collaborative system with two co-located transmit antennas and one receive antenna, operating in a lognormal shadowing environment, and the collaborative system for which the two antennas are located at the base station and on the relay mobile station. The results show considerable reduction of the outage probability through the use of collaboration.