In this paper, the average packet delay on IEEE 802.11 DCF under finite load traffic in multi-hop ad hoc networks is analyzed. We employ a Markov chain model to analyze the probability of transmission at each node in ...In this paper, the average packet delay on IEEE 802.11 DCF under finite load traffic in multi-hop ad hoc networks is analyzed. We employ a Markov chain model to analyze the probability of transmission at each node in an arbitrary slot and derive the channel access delay. We model each node using an M/G/1 queue and derive the queueing delay. The model is extended from analyzing the single-hop average packet delay to evaluating the end-to-end packet delay in multi-hop ad hoc networks without assuming the traffic to be in a saturation state. To validate our analytic results, we have done extensive simulation. The analytic and the simulation results match very well.展开更多
A load-balancing scheme for IEEE 802.11 WLANs based on cooperative game theory is presented.A coalition among the access points(APs) with overlapping coverage is formed to share the network load through a game.First...A load-balancing scheme for IEEE 802.11 WLANs based on cooperative game theory is presented.A coalition among the access points(APs) with overlapping coverage is formed to share the network load through a game.Firstly, the candidate APs submit their load-competing strategies(i.e., the amount of user traffic they can admit in an AC/game period) to the control AP.Secondly, the control AP solves the game by the method of shapley value, which is the maximum traffic allocated to each AP in an AC/game period.Finally, the game is repeated periodically to distribute the traffic load among the APs.Simulation results show that the proposed game can balance the network load effectively compared with the IEEE 802.11 standard balancing solution.展开更多
In WLANs, stations sharing a common wireless channel are governed by IEEE 802.11 protocol. Many conscious studies have been conducted to utilize this precious medium efficiently. However, most of these studies have be...In WLANs, stations sharing a common wireless channel are governed by IEEE 802.11 protocol. Many conscious studies have been conducted to utilize this precious medium efficiently. However, most of these studies have been done either under assumption of idealistic channel condition or with unlimited retransmitting number. This paper is devoted to investigate influence of limited retransmissions and error level in the utilizing channel on the network throughput, probability of packet dropping and time to drop a packet. The results show that for networks using basic access mechanism the throughput is suppressed with increasing amount of errors in the transmitting channel over all the range of the retry limit. It is also quite sensitive to the size of the network. On the other side, the networks using four-way handshaking mechanism has a good immunity against the error over the available range of retry limits. Also the throughput is unchangeable with size of the network over the range of retransmission limits. However, the throughput does not change with retry limits when it exceeds the maximum number of the backoff stage in both DCF’s mechanisms. In both mechanisms the probability of dropping a packet is a decreasing function with number of retransmissions and the time to drop a packet in the queue of a station is a strong function to the number of retry limit, size of the network, the utilizing medium access mechanism and amount of errors in the channel.展开更多
在分析IEEE802.11DCF机制的基础上,针对IEEE802.11WLAN(Wireless Local Area Networks,WLAN)传输性能异常问题,提出在多节点多速率WLAN环境中根据传输速率变化适时调整数据包和竞争窗口值大小的解决方案。应用基于NS2的仿真模型进行了...在分析IEEE802.11DCF机制的基础上,针对IEEE802.11WLAN(Wireless Local Area Networks,WLAN)传输性能异常问题,提出在多节点多速率WLAN环境中根据传输速率变化适时调整数据包和竞争窗口值大小的解决方案。应用基于NS2的仿真模型进行了系列比较实验,仿真结果验证了新方法的有效性。展开更多
基金the National Natural Science Foundation of China (Grant Nos. 60472078 and 90604013)
文摘In this paper, the average packet delay on IEEE 802.11 DCF under finite load traffic in multi-hop ad hoc networks is analyzed. We employ a Markov chain model to analyze the probability of transmission at each node in an arbitrary slot and derive the channel access delay. We model each node using an M/G/1 queue and derive the queueing delay. The model is extended from analyzing the single-hop average packet delay to evaluating the end-to-end packet delay in multi-hop ad hoc networks without assuming the traffic to be in a saturation state. To validate our analytic results, we have done extensive simulation. The analytic and the simulation results match very well.
基金supported by the Aviation Science Fund (20080196005)
文摘A load-balancing scheme for IEEE 802.11 WLANs based on cooperative game theory is presented.A coalition among the access points(APs) with overlapping coverage is formed to share the network load through a game.Firstly, the candidate APs submit their load-competing strategies(i.e., the amount of user traffic they can admit in an AC/game period) to the control AP.Secondly, the control AP solves the game by the method of shapley value, which is the maximum traffic allocated to each AP in an AC/game period.Finally, the game is repeated periodically to distribute the traffic load among the APs.Simulation results show that the proposed game can balance the network load effectively compared with the IEEE 802.11 standard balancing solution.
文摘In WLANs, stations sharing a common wireless channel are governed by IEEE 802.11 protocol. Many conscious studies have been conducted to utilize this precious medium efficiently. However, most of these studies have been done either under assumption of idealistic channel condition or with unlimited retransmitting number. This paper is devoted to investigate influence of limited retransmissions and error level in the utilizing channel on the network throughput, probability of packet dropping and time to drop a packet. The results show that for networks using basic access mechanism the throughput is suppressed with increasing amount of errors in the transmitting channel over all the range of the retry limit. It is also quite sensitive to the size of the network. On the other side, the networks using four-way handshaking mechanism has a good immunity against the error over the available range of retry limits. Also the throughput is unchangeable with size of the network over the range of retransmission limits. However, the throughput does not change with retry limits when it exceeds the maximum number of the backoff stage in both DCF’s mechanisms. In both mechanisms the probability of dropping a packet is a decreasing function with number of retransmissions and the time to drop a packet in the queue of a station is a strong function to the number of retry limit, size of the network, the utilizing medium access mechanism and amount of errors in the channel.
文摘在分析IEEE802.11DCF机制的基础上,针对IEEE802.11WLAN(Wireless Local Area Networks,WLAN)传输性能异常问题,提出在多节点多速率WLAN环境中根据传输速率变化适时调整数据包和竞争窗口值大小的解决方案。应用基于NS2的仿真模型进行了系列比较实验,仿真结果验证了新方法的有效性。