INTEGRATED LT CODING, BIT INTERLEAVED DIFFERENTIAL SPACE TIME CODING AND SPHERE PACKING MODULATION FOR THE WIRELESS INTERNET

摘要

In this treatise, a jointly optimized Bit Interleaved Coded Modulation using Iterative Decoding (BICM-ID) and Luby Transform (LT) coding scheme was proposed for the sake of attaining the best possible performance, when communicating over the wireless Internet. This scheme is particularly attractive when handling packetized wireless Internet data traffic received over wireless channels inflicting both statistically multiplexing induced packet erasure and packet corruption imposed by the channel without retransmitting the corrupted packets. A LLR-based estimation packet reliability algorithm was proposed to assist the LT decoder in recovering all the transmitted packets. Furthermore, the bit-to-sphere-packing-symbol mapping scheme was optimized for achieving error free LT decoding at the lowest possible E{sub}b/N{sub}0 value rather than for approaching the channel's capacity. These two design philosophies require different mapping schemes. Finally, Differential Space Time Coding (DSTBC) was employed for combatting the effects of fading and provided spatial diversity at the same time. The LT code's packet length was also carefully chosen to strike a good balance between the affordable complexity and the achievable performance.