Hybrid Scheduling Mechanisms for Channel Access in Wi-FiNetworks

• Main Authors: Hung, Hung-Wei, 洪鴻維
• Other Authors: Tseng, Yu-Chee
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/d974qg

碩士 === 國立交通大學 === 網路工程研究所 === 106 === With the growing traffic demands of new data-intensive applications, users are expecting ubiquitous wideband wireless access. Though emerging wireless technologies target for ultra-high-speed WiFi, the achievable throughput in practice is still low due to bandwidth underutilization caused by collisions. Existing solutions address such underutilization by combiningCSMA/CA with TDMA-based scheduling. However, as TDMA-based scheduling highly relies on traffic patterns of users, those hybrid systems usually fall back to CSMA/CA when a scheduled client has no traffic demand, again suffering from collisions. To resolve this issue,thisthesispresentsCA-PCR(CSMA/CAwithpartialcounterreservation), a TDMA-like carrier sensing multiple access control protocol. Unlike existing hybrid schemes, which still experience underutilization when traffic demands fluctuate, our design ensures full collision-free utilization based only on carrier sense even without knowing the dynamic traffic patterns of clients. We achieve this by a lightweight counter reservation protocol and a novel counter permutation mechanism. Our evaluation results show that CA-PCR improves spectrum utilization via an eligible overhead and delivers a significant throughput enhancement.