| Summary: | 碩士 === 國立臺灣大學 === 電機工程學研究所 === 96 === Nowadays, IEEE 802.11 based wireless devices are widely deployed. The new 802.11p
standard is an amendment of legacy 802.11 to provide wireless access in vehicular networking
environment. In this work, we propose an 802.11p compatible mechanism to
ensure guaranteed QoS for the vehicular applications. Vehicular wireless devices move
within their transmission range during a limited timeframe. Traffic alerting messages and
protocol signaling messages require guarantee QoS transmission within the limited time
duration. To transmit high priority data packets during these time-constraint transmission
opportunities, MAC level support is essential for opportunistic networking design in
vehicular wireless networks. In addition, current 802.11e QoS mechanism only provides
differentiated QoS but not guaranteed QoS. Under such contention-based 802.11 environment,
there are strong needs to provide assured delivery mechanism for opportunistic
access. Since hard guaranteed QoS in wireless random access networks is unlikely
achievable, we proposed a soft guaranteed QoS mechanism for 802.11 based systems. To
understand the benefit of our design, we use Markov chain model to evaluate this system.
We also use NS-2 simulations to validate the performance model. The performance
results show that the proposed scheme has better performance both on throughput and
successful transmission probability within a given time period.
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