Coverage prediction for 5-GHz-band high-speed digital signal transmission in urban street microcells

This paper reports coverage prediction results for 5-GHz-band TDMA mobile communication systems that transmit high-speed digital signals at bit rates of 2 Mb/s to 30 Mb/s in urban microcell environments. The predictions are mainly based on radio propagation characteristics obtained by ray-tracing calculations on an urban line-of-sight street. Based on the predicted propagation loss and delay spread characteristics, bit error rate (BER) characteristics for differential QPSK signals with two- or four-branch maximum ratio combining diversity reception are evaluated. Adaptive beam-facing access (ABFA) is proposed, and its effectiveness in reducing delay spread in microcell environments is evaluated numerically and experimentally. Using ABFA and 2-branch maximum ratio combining (2-MRC) diversity reception, a 2 Mb/s TDMA signal can be transmitted with 95% area coverage (600 m range from base site) with the BER performance of better than 10^-5. Similarly, using ABPA and 4-MRC, a 25 Mb/s TDMA signal can be transmitted with the same signal quality over 100 m range from base site