Performance Comparison of OFDM-TDMA and OFDMA with Cross-Layer Consideration

Performance comparison of multiuser OFDM-TDMA and OFDMA systems by considering physical and link cross-layer behavior is conducted in this work. We provide a new framework for performance evaluation that centers on "scheduling" with several different subcarrier/bit allocation schemes. The performance metrics include: the bit rate, the bit error rate (BER), packet throughput and delay. The instantaneous channel conditions of users are assumed to be available at the base station, which can be achieved by channel estimation at the mobile terminal (MT), and then fed back to the base station through a control channel. To perform the link layer comparison, we model the Rayleigh fading channel with a finite-state Markov chain, and adopt the M/G/1 queueing model as the analytical tool. Computer simulation is performed to verify conducted analytical results.