Performance Characterization of Cellular Networks with Pilot-Aided Non-Coherent Joint Transmission

Abstract:
This paper investigates the performance of downlink cellular networks with non-coherent joint (mutlipoint) transmissions and pilot-aided channel estimation. Under a stochastic geometry framework, the spatial average signal-to-noise-ratio (SNR) is characterized, taking into account the effect of channel estimation error due to additive noise and pilot contamination. A simple, easy to compute SNR expression is obtained under the assumption of randomly generated pilot sequences and minimal prior information about the channels and positions of access points (APs). This SNR expression allows for the efficient joint optimization of critical system design parameters such as number of cooperating APs and pilot (training) overhead. Among others, it is shown that multipoint transmissions are preferable to conventional non-cooperative cellular operation when the main cause of channel estimation errors is pilot contamination, with the cooperation gains becoming more prominent under propagation conditions with a large path loss factor.