Relay-based vs. Conventional Wireless Networks: Capacity and Spectrum Efficiency

Conventional radio cells suffer from the disadvantageous distribution of the transmission rates. High transmission rates are only available in the close vicinity of the access point, whereas the distribution of mobile stations behaves complementary. Hence, the provided capacity of the access point is only partly used and the majority is wasted. This drawback will grow with the introduction of future transmission techniques, which increase the maximum transmission rates available at short distances. Therefore, it is unlikely that the traditional design of cellular radio systems can achieve the ambitious throughput and coverage requirements of fourth- generation (4G) radio networks. We propose to extend conventional multi-cellular systems by applying relay-enhanced topologies to each cell. To encourage this evolutionary step we present an analytical model to compute the upper bound capacity and the spectrum efficiency of wireless networks. Based on this analytical model the potential of conventional cellular systems is compared with relay-enhanced networks.