Performance of real time cooperative MIMO using an SDR platform

Fading remains the prime problem in wireless communications, and line of sight communication is not possible everywhere. Multiple Input Multiple Output (MIMO) is a technique used to mitigate multi path fading effects by physically placing multiple antennas to create independent channel realizations. Cooperative MIMO on the other hand generates the effect of MIMO through cooperation of distributed radio nodes within the network. The paper identifies performance gains achieved in terms of frame error rate versus average signal to noise ratio of cooperative communication networks over conventional SISO and multiple collocated antenna array systems. An experimental testbed is developed on a Software Defined Radio (SDR) platform comprising of three distributed network nodes operating in the 2.4GHz unlicensed ISM band. A Selective Decode and Forward (DF) cooperative protocol is developed and established between the nodes. The results have been evaluated in terms of diversity gains as measured from the experimental curves of FER versus average SNR. A comparative analysis reflects that at a fixed value of SNR the FER of CMIMO communication systems is less than SISO, SIMO and single antenna cooperation networks.