Research On Distributed Space-Time Coding In Ad Hoc Networks

Multiple Input Multiple Output (MIMO) based Space-Time Coding (STC) can greatly combat the channel fading and in turn improve the performance of the system. In some wireless communication environments (taking Ad hoc networks for examples), it is costly or difficult to equip multiple antennas on mobile terminals. Hence, STC can not be applied directly. The introduction of virtual MIMO provides an effective approach for the solution of this problem. By applying STC to virtual MIMO systems, a distributed Space-Time Coding (DSTC) structure can be realized. As a result, cooperative diversity gain can be obtained to upgrade the system.Based on Ad hoc network architecture, a physical layer transmission model based on data-packet transmission range (DPTR) and control-packet transmission range (CPTR) is investigated. With this transmission model, the performance of DSTC with AF-MMSE and AF-ZF are analyzed, respectively. Specifically, the corresponding maximal ranges of one transmission of DSTC are determined. Both theoretical analyses and simulation results indicate that AF-ZF outperforms AF-MMSE because the inter-symbol interference can be eliminated by AF-ZF.