QoS-aware Link Rate Adaptation in IEEE 802.16 Broadband Wireless Access Systems

IEEE 802.16 broadband wireless access system (BWA) is a promising emerging technology. In the IEEE 802.16 standard, multiple data transmission rates are defined by employing different modulation and channel coding schemes. How to select a proper mode affects the system performance significantly. In this paper, an efficient link rate adaptation algorithm, named QoS-aware link rate adaptation (Q-LRA), is proposed. Q-LRA takes both QoS demand and channel condition into consideration to determine the best mode. The QoS demand of a connection is represented as packet error rate (PER). Based on the specified PER, the BS calculates the required signal-to-noise ratio (SNR) threshold of each mode. By comparing the measured SNR and all modes´ SNR thresholds, the BS suggests the SS the best mode. The performance of Q-LRA is evaluated by simulations. The simulation results show that Q-LRA improves system throughput and guarantees each connection´s QoS demand.