Coded Diversity Combining and Channel Estimation for Wireless Data Communications

点击翻译按钮获取中文摘要

Recently, a new post-detection macrodiversity scheme was proposed for cellular communication systems. In this new scheme, termed Multiply-Detected Macrodiversity (MDM), the signals at multiple base stations are detected and used as input to a Decision Algorithm, which provides an optimal decision of what was transmitted. The MDM scheme shows considerable improvement in the Bit-Error Rate (BER), especially when the mobile is close to the boundary between cells. As the boundary between cells is exactly the region in which the quality of the mobile's signal is mostly impaired, the MDM scheme has the effect of equalizing the BER throughout the system coverage area. The Decision Algorithm of the MDM scheme requires as an input, in addition to the separate detections of the receivers, also an estimation of the quality of the received signals, so that appropriate"weightings" of these signals can be applied in the post-detection combining process. To obtain estimates, usually some sort of channel measurement is performed; e.g., the signal power (S-diversity) or the Signal-to-Interference-Ratio (S/I-diversity). In such cases, the measurement process complicates the design of the transmitter/receiver hardware and the operation of the system. Furthermore, the measurements are subject to high variance and need to be averaged over time. To avoid the disadvantage of the measurement-based quality of signal estimation, we propose here to investigate the use of channel coding to evaluate the transmission characteristics of a wireless channel for macrodiversity reception. The proposed channel estimation schemes use side information generated during the decoding process.In summary, we intend to study the use of the MDM combining with coded channel estimation in the case of a single site equipped with multiple,widely-separated receivers and in the case of multiple cell sites. In the latter case, we will investigate the use of both post-detection and predetection combining (with quantization of the recei ved signal), comparing the performance in the schemes in the presence of channel impairments characteristic to the mobile communication environment.