Multi-user indoor ultra-wideband wireless communication using polyphase spreading sequences

In this study, the authors design a multi-user ultra-wideband system for indoor wireless communication. The proposed system is useful in multipath radio reception as the full multipath diversity gain is achieved. The system has multiple transmitters and receivers. They use polyphase spreading waveforms which feature low levels of mutual interference and enable each of the channel impulse responses to be measured free from distortion continuously with each data symbol transmission. A key feature of the proposed system is that transmitted waveforms are used which produce outputs from the receiver cross correlators, which are zero on both sides of the main correlation peak, for each radio path. This zero response lasts for a duration in excess of the expected delay spread of the radio channel enabling full Rake processing of the multipath signal. The effects of the low levels of mutual interference are reduced further by using time and frequency hopping, forward error correction and soft decision decoding.