Channel quality indication for adaptive resource scheduling in Multihop OFDMA systems

IMT-advanced systems of the future will be based on OFDMA and frequency divicion duplex will be widely used. Multihop techniques, e.g. the use of fixed relays, are also considered a key technology. The OFDMA resources have the dimensions time, frequency and space. In all these dimensions a radio channel is variable due to fading. On the other hand a complete utilization of the channel capacity close to the Shannon bound is required. Therefore all channel adaptive modulation and coding schemes require good channel state information. For FDD this needs to be signalled back from user terminals to base stations or relays, so that the adaptive scheduling algorithms there can decide optimally. This is performed by channel quality indication. This paper discusses a multimode-capable multistage CQI concept for IMT-advanced systems, shows measurements from simulation and provides the system view including CQI.