A novel algorithm for link adaptation using fuzzy rule based system for wideband networking waveform of SDR

Adaptive and high speed communication with changing user requirements and environment conditions are the future needs of wireless networks. This is achieved by using the available resources optimally to increase the overall throughput by satisfying specific constraints. In this paper, a link adaptation algorithm for a hybrid multicode CDMA/adaptive TDMA based wideband networking waveform of SDR is proposed. The requirement of link adaptation increases when the transmissions are in the form of network packets. A low value of bit error rate can drastically increase packet error rate and thus packet re-transmissions, if the signal and protocol parameters are not dynamically changed according to the channel conditions and tolerable bit error rate. A constrained optimization problem has been formulated under the Quality of Service and throughput constraints. The optimization problem has been solved using fuzzy rule based system by dynamically changing the modulation technique and the number of multicodes assigned to each user. Simulation results are presented to demonstrate the effectiveness of the proposed algorithm in achieving better throughput by efficiently reducing the packet re-transmissions overhead.