Novel minipacket design and decoding performance improvement with additional parity information in wireless hybrid ARQ systems

Abstract

Currently, wireless communication systems are wide-spread among public and private areas, including wireless phones (CDMA/WCDMA/GSM), wireless networks (Wireless LAN/HiperLAN/Wibro), wireless broadcastings (DVB/DAB). The wireless channels used in the commercial systems are allocated by the corresponding regulatory agency, where high usage fee is required for each band allocation. Therefore, the subscribers of these systems are request to pay relatively high cost compared to wired line communication. In this dissertation, we first inspect the wireless channel usage of the conventional wireless communications. Particularly, we note that the packet transmission overhead is caused by the high bit error rate due to fading channel effects or wireless interferers or local device problems. For the timing synchronization and channel estimation, every transmission packet should be guarded with a preamble. In order to reduce the effects of high bit error rates, error checking method, error correction method, link reliability protocol, and frame guard time are usually used in packet transmissions. The amount of these overhead becomes significant when the bit error rate goes up. To reduce the effect of these overhead even for high error rates in wireless communication channels, we try various approaches: frame length control, advanced repeat retransmission scheme, partial retransmission scheme, feedback scheme of received/decoded packet status, parity guarded symbol modulation, and decoding methods for error correction codes. The reduction scheme can be categorized into three schemes: 1) transmitter-side adaptation scheme to the current channel status, 2) receiver-side adaptation scheme to mitigate the channel disturbance, and 3) decoding algorithms for the improved error correction capability. In the transmitter side, frame length control is first checked. The frame length control enhances the reception probability at the receiver, which results in the better transmission ...