A delay analysis model for Multichannel Random Access in OFDMA systems

The combination with Orthogonal Frequency Multiple Access (OFDMA) technology is an effective approach for improving the performance of random channel access in wireless broadband networks, such as LTE, WiMax and the next-generation WLAN. In this paper, we propose a mathematical model to analyze the delay performance of an OFDMA-random-access system under unsaturated load condition. The proposed model adopts a general distribution for the duration of each time slot. In this way, the model no longer depends on a certain protocol. On the other hand, our model supports a more general setting, that is, a terminal may simultaneously access multiple subchannels in the system. Under this general assumption, we investigate the system delay performance and the stability condition. Simulation results not only show the accuracy of the presented analysis, but also demonstrate that the analysis based on saturated load assumption may underestimate the actual performance of the OFDMA-random-access system.