Joint sub-carrier and packet size allocation in OFDM systems

A joint sub-carrier and packet size allocation(JSPSA) strategy is proposed to enhance the goodput in orthogonal frequency division multiplexing(OFDM) systems.It produces more degrees of optimization freedom than the traditional optimization strategies.Based on the JSPSA strategy,the monotonicity of the goodput function of the joint allocation is studied in the flat fading channel.It is proved that the goodput function is a unimodal function.Furthermore,it is shown that the monotonicity of the goodput function in the selective fading channel is similar to that in the flat fading channel.Therefore,a JSPSA algorithm for the selective fading channel is presented by introducing a new equivalent channel gain.Analytical and simulation results illustrate that the performance of the proposed JSPSA algorithm is almost the same as the enumeration method and is comparable to the existing greedy algorithm bit allocation/equal bit error rate(BER) power allocation(GABA_EBPA) algorithm.The JSPSA algorithm makes a better trade off between complexity and performance by reducing the complexity significantly.