An OFDM Based Adaptive Modulation Scheme Employing Variable Coding Rate in Dynamic Parameter Controlled OF/TDMA Systems

In this paper, we introduce variable coding rate (VCR) control to OFDM adaptive modulation scheme (OFDM AMS) in order to realize high throughput with relatively simple transceiver configurations in a dynamic parameter controlled-orthogonal frequency and time division multiple access (DPC-OF/TDMA). In the proposed system, multilevel transmit power control (MTPC) is not employed to simplify hardware. Instead, we will introduce a VCR control technique that reduces the required signal to interference plus noise power ratio (SINR) gap between adjacent modulation and coding scheme (MCS) in the OFDM AMS, thereby reducing surplus power between the actual received SINR and the required SINR. Furthermore, this paper also presents a bit loading algorithm to effectively transmit MAC payloads with certain fixed lengths. Throughput performances obtained from computer simulations confirm that the proposed VCR OFDM AMS can be a good alternative to the OFDM AMS/MTPC. Keywords— OFDM, adaptive modulation scheme, variable coding rate, bit loading, DPC-OF/TDMA, one-cell reuse TDMA