High capacity strategies for GSM/EDGE - impacts on data traffic performance

GSM is the world´s most widespread cellular technology. With EDGE packet data, an attractive solution to offer 3rd generation cellular services in existing GSM networks is provided. The introduction of new services into an existing network typically leads to increased capacity demands, since more users of different service types need to coexist in a limited spectrum, while the existing speech service is required to function at least as well as before. In GSM/EDGE systems, the highest capacity is reached in interference-limited scenarios, typically realized with tight frequency reuse and fractional loading; see for example P. de Bruin et al. (IEEE Vehicular Society News, vol.49, no.1, 2002). In such systems, methods for mitigating interference are needed to achieve maximum performance. Strategies for frequency hopping, inter-cell synchronization and MAIO (mobile allocation index offset) planning becomes increasingly important. The paper examines the impact these methods have on EDGE packet data performance. It is shown that packet data traffic responds differently than speech to interference diversity, mainly due to differences in channel coding and radio protocol characteristics. However, it is demonstrated that the intercell synchronization and MAIO planning strategies preferred for pure speech networks also offer substantial performance improvements for EDGE packet data.