| Summary: | 碩士 === 雲林科技大學 === 資訊工程研究所 === 98 === This thesis focuses on the design of communication strategies between vehicles to roadside unit (V2R). We assume the V2R is operation in highway environment. Each vehicle may carry high-priority data, low-priority data, or high/low-priority simultaneously. Once the vehicle moves to the signal coverage range of RSU, the carried data in each vehicle must be uploaded to the RSU. For reducing the contentions among vehicles within the signal coverage range of RSU, the IEEE 802.11 PCF MAC protocol cooperating with scheduling algorithm in RSU is used to guarantee the high-priority data in vehicle can be uploading to RSU.
In the IEEE 802.11 PCF MAC, the bandwidth is divided into two parts: contention-free period and contention period. The scenario of V2R communication in this thesis is that the vehicle sends the bandwidth request packet to the RSU during the contention period. After collecting all of bandwidth request packets, based on the scheduling algorithm the RSU assigns the bandwidth to the vehicle to upload its carried data to RSU. In this thesis, an adaptive contention window (CW) scheme is applied in vehicle to reduce the signal collision to improve the channel utilization during the contention period. That is the vehicle carried high-priority data has a smaller CW value. Thus, the vehicle carried high priority data has a higher probability to sent the bandwidth request packet to RSU. According to the vehicular bandwidth requesting, a scheduling algorithm cooperated with linear programming technique is applied in RSU for deriving a suitable bandwidth allocation scheme to maximize the number of success data uploading rate from vehicle to RSU and minimize the high-priority data loss rate (can’t success upload to RSU). Moreover, for further evaluation the proposed scheme, we develop a simulation model with C langurage to compare the performance of the proposed scheme with other schemes. The simulation results reveal that the proposed scheme has a good performance in term of success data uploading rate.
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