System Design and Throughput Analysis for Multihop Relaying in Cellular Systems

Wireless multihop relaying can provide a great improvement in systemwide throughput and coverage in a cellular system. However, since additional resources (time or frequency slots) and overhead are required to perform relaying, the addition of relays into a cellular system must be carefully designed for the system´s specific geometry, topology, and propagation environment. Maximizing the benefit of multihop relaying requires that the medium access control (MAC) layer scheduler be aware of physical (PHY) layer conditions. Multihop relaying increases networkwide throughput by enabling spatial reuse within a cell and by significantly reducing the path loss on each hop. The most significant gain results from adding enough relays to create line-of-sight (LOS) paths on all relay hops. To assist with system design, we present a methodology of analyzing network throughput and area-averaged spectral efficiency for multihop relay-enhanced cellular systems, including cross-layer considerations. In addition, we describe a technique that may be used to determine spatial reuse schedules. In this paper, we use a realistic model and typical cellular scenarios to show how relaying can be used to improve coverage and throughput in a real-world system.