The use of intelligently deployed fixed relays to improve the performance of a UTRA-TDD system

This paper examines the use of intelligently deployed fixed relays to improve the performance of an UTRA-TDD 3G system. In this study, the benefits of intelligent relaying in the form of enhanced capacity and/or coverage and reduced RF emissions relative to a traditional cellular network are quantified. Simulations are carried out in a microcellular environment using propagation data from a site-specific model and an optimisation algorithm to determine the locations of base stations (BSs) and relay nodes in the system. A system level simulation of an UTRA-TDD system is used to quantify the benefits of the relayed over the non-relayed system. Results show significant improvements in capacity, spectrum efficiency and reductions in mean terminal transmit power in the relayed system over conventional cellular BS-only operation. The effects of different code allocation strategies for the relay nodes are also investigated, revealing that benefits in relaying would only be realised if code re-use between the BSs and relay nodes is enabled or if relay nodes are allocated their own pool of spreading codes.