A Channel Access Scheme to Compromise Throughput and Fairness in IEEE 802.11p Multi-Rate/Multi-Channel Wireless Vehicular Networks

Abstract

Wireless access in vehicular environment (WAVE) architecture of intelligent transportation system has been standardized in the IEEE 802.11p specification. The WAVE network supports the features of multi-rate and multi-channel and it is going to be widely deployed in realistic roadway environments in order to provide traffic information and convenient services. However, the adopted contention-based medium access control protocol, which confronts the performance anomaly problem, would severely downgrade transmission efficiency between roadside-unit (RSU) and on-board-unit (OBU) because they may use diverse data transmission rates to access channel. As a solution, this paper proposes the vehicular channel access scheme (VCAS) to group a number of OBUs with similar transmission rates into one channel to optimize the channel throughput, while the group sizes of channels are controlled in order to fulfill the fairness requirement. To flexibly compromise the tradeoff between throughput and fairness, a marginal utility model is proposed in this paper. Simulation results demonstrate that the proposed VCAS with marginal utility provides a flexible way to handle versatile vehicular scenarios.

Fairness Assurance through TXOP Tuning in IEEE 802.11p Vehicle-to-Infrastructure Networks for Drive-Thru Internet Applications

“…The low data transfer for fast vehicle is caused by the DCF protocol which does not consider residence time of a vehicle for granting channel access. Further, we observe that for default MAC settings, the ratio of data transferred per node for slow and fast vehicles is equal to the ratio of their mean residence times, thus validating our analytical result of (21). When TXOP values are selected according to (21), the amount of data transferred by slow as well as fast vehicles are observed to be equal.…”

“…Further, we observe that for default MAC settings, the ratio of data transferred per node for slow and fast vehicles is equal to the ratio of their mean residence times, thus validating our analytical result of (21). When TXOP values are selected according to (21), the amount of data transferred by slow as well as fast vehicles are observed to be equal. However, we observe a slight reduction in the total amount of data transferred (in Table 7) for the optimal case compared to the default case.…”

“…Several attempts have been made to analyze and evaluate the performance of IEEE 802.11p standard for vehicular networks in terms of throughput and other related measures [11][12][13][14][15][16][17][18][19][20][21][22][23]. In [13,14], authors propose analytical models to evaluate the performance and the reliability of IEEE 802.11a-based V2V safety-related broadcast services in DSRC system on highway.…”

“…In [19,20], authors derive analytical models to characterize the average and the distribution of the number of bytes downloaded by a vehicle by the end of its sojourn through an AP's coverage range, in the presence of contention by other vehicles. Authors of [21] propose a new vehicular channel access scheme to compromise the trade-off between system throughput and throughput fairness in V2I networks. In [23], authors conduct a study on association control over the drive-thru Internet scenario for a V2I network.…”

“…When optimal TXOP is chosen according to (21), the ratio of bits transferred per node for slow and fast vehicles become equal to unity, thus resulting in bit based fairness. Under default TXOP setting in which TXOP values are selected as equal, for all vehicles irrespective of their velocities, the above ratio is equal to the ratio of residence times of slow and fast vehicles.…”