Capacity of a relaying infrastructure for broadband radio coverage of urban areas

Owing to the difficult propagation conditions in the frequency range of future cellular broadband radio systems, very small cell sizes and high attenuation through obstacles (sufficient C/I ratio only in direct line of sight (LoS)) are expected to constitute a major challenge for the development of such systems. Thus, complete coverage of urban areas using a conventional (one-hop) cellular infrastructure is expected to be very costly due to the high number of base stations and fixed network connections needed. For this reason, the introduction of relaying is widely accepted to be an essential element in the development of future cellular broadband radio networks. This paper presents a methodology to quantify the influence of relaying on the capacity of a single base station. We define the capacity as the aggregate downlink throughput that is achieved by all users in the cell. Inspired by the recently proposed wireless media system (WMS) architecture [B. Walke, et al., Apr. 2003], we compare the capacity of a conventional one-hop cellular architecture with the capacity of a configuration consisting of one base station and four regenerative fixed relay stations (FRS) that together cover the same area like five base stations in a conventional cellular architecture. The presented methodology allows exploring the parameter space, which is spanned by system parameters like antenna gain, scenario geometry, and noise and transmitting power.