Advanced power calibration for random access in the IEEE 802.16 system

Abstract

Random access channel is incorporated in IEEE 802.16 WiMAX system to transport contention-based messages in the uplink, such as bandwidth requests generated by best effort applications, from mobile stations (MSs) to the base station (BS). Regarding the packet transmissions in the random access channel, delay, throughput and power consumption are usually considered as major performance metrics. We propose an enhanced power calibration protocol to optimize the system performance in terms of channel access delay, system throughput and MS transmit power consumption. Optimal selection of power levels is formulated in order to maximize the achievable throughput while being subject to power consumption constraint of mobile stations. Our scheme can substitute the random backoff mechanism in the current the WiMAX uplink random access channel, as it can accomplish a significantly improved access delay performance without an increment of design complexity. Simulations are conducted to validate our protocol and confirm its performance superiority as compared to the random channel access method used in the current WiMAX.

Joint collision resolution and transmit‐power adjustment for Aloha‐type random access

“…The authors of Reference [20] considered power control to meet the delay performance of slotted Aloha, assuming common feedback from the the access point. Power control with random access was also considered in References [21,22] based on random backoffs rather than slotted Aloha, specifically for IEEE 802.16 systems. To the best of our knowledge, little has been done on resolving randomaccess failures by considering both collision resolution and transmit-power adjustment together for Aloha-type random access.…”