Carrier to Interference Ratio Modelling for Edge Radio Networks

With an increasing demand on multimedia services, a design of high-speed data networks is an important task in the wireless mobile environment. EDGE (Enhanced Data rates for Global Evolution) is the next step in the evolution of GSM and IS-136 offering high data rate capabilities in the existing GSM spectrum [1] [2]. With the introduction of EDGE in GSM phase 2+ existing services like GPRS (based on packet switching technique) and HSCSD (based on circuit switching technique) are improved by presenting a new physical layer. The services themselves are not modified. In order to achieve higher data rates, EDGE introduces the new modulation scheme – linear 8 Phase Shift Keying (8PSK). It is capable of providing a gross data rate, which is approximately three times higher than GPRS in the same bandwidth of 200 kHz. The conventional GMSK (Gaussian Minimum Shift Keying) modulation of GSM may still be used in situations where a more robust modulation is required. A characteristic of cellular systems is the varying link quality within a cell. Therefore, different modulation and coding schemes are required for different link qualities. For EDGE, nine modulation-coding schemes are defined. Several adaptation and quality control techniques have been proposed (ARQ, Link Adaptation, Incremental Redundancy, Radio Link Control) [2] [3].