Cooperative Network Communications in Dynamic Channel Environments

Coded space-time cooperation is a powerful approach to deliver information over a distributed network. Multiple transmit and receive nodes form a distributed multiple-input-multiple-output (MIMO) system, thus provide the capability of high data rate transmission with the support of high diversity gains. However, unlike co-located MIMO systems, it is impractical for distributed MIMO networks to maintain a perfect synchronization between different transmit terminals. It has been shown that, in the presence of synchronization error between different relaying nodes of even a fractional symbol, coded cooperation using space-time block codes may experience severe inter- symbol interference (ISI) and, subsequently, significant performance degradation. It becomes even more challenging when Doppler effect exists as the result of moving transmit and/or receive nodes. In this paper, we propose the use of BLAST-type of data transmission combined with effective channel coding. The relative independence between the information transmitted from different nodes allows individualized compensation of the time delay and Doppler shift, whereas the channel coding of the information across different transmit nodes assures high spatial diversity. As the result, the proposed scheme is capable in maintaining a high data rate in a dynamical channel environment. It provides robust and reliable communication quality by taking advantages of spatial information multiplexing and spatial diversity.