Relay communications over frequency-selective fading channels.

摘要

Wireless communications over long distances can be assisted by a third radio acting as a relay. If the relay is placed close to the source, then the source-relay link will be characterized as a fairly benign additive white Gaussian noise (AWGN) channel. However, the long distance link from relay to destination is susceptible to frequency-selective fading. This thesis explores the design and analysis of a particular relay communication system characterized by a low power source, a relay that is close to the source, and a frequency-selective channel from relay to destination. Because the direct link from source to destination is very weak, it is not exploited, but rather communications is via a traditional two-hop process.;Link design is based on the high speed download packet access (HSDPA) standard, which uses a combination of turbo coding, hybrid-ARQ, and multicode CDMA. To provide further diversity, the relay-destination link uses a secondary spreading code, rake reception, and multiple receive antennas. An extensive analysis was conducted to study the influence of a wide variety of link configurations and channel conditions. The study was accelerated through the use of a quasi-analytical approach based on the concept of information-outage, which allows the link to be simulated without requiring a turbo decoder.