Investigations on BLER requirements of associated control channels for IP packet transmission in forward link for VSF-OFCDM broadband packet wireless access

We have investigated experimentally the influence of decoding errors of associated control channels (CCHs) on the achievable packet loss rate (PLR), and the throughput performance of IP packet transmission using a shared forward packet data channel (FPDCH) employing hybrid automatic repeat request (ARQ) with soft combining in the medium access control (MAC) layer for orthogonal frequency and code division multiplexing (OFCDM) broadband wireless access in the forward link. Using broadband base station (BS) and mobile station (MS) transceivers with forward and reverse link channel bandwidths of 100 MHz and 40 MHz, respectively, we applied turbo and convolutional coding to a shared FPDCH and the associated CCHs along with a very short transmission time interval (TTI) of 0.5 msec. Laboratory experiments using hardware fading simulators show that the average block error rate (BLER) of the forward link CCH (FCCH) should be identical to the required PLR of the shared FPDCH for real-time traffic data and be less than approximately 10^-2 for non-real-time traffic data to avoid decreasing the throughput, and that of the reverse link CCH (RCCH) should be less than approximately 10^-2 to avoid an increase in the code channel utilization rate. Furthermore, we validate the laboratory results by field experiments in a real propagation channel, which are conducted in a cellular environment with a cell distance of approximately 1 km at an average speed of 30 km/h.