Ieee 802.11n Mac Layer Dynamic Aggregation Frame Length Mechanism

With the rapid development of science and technology, computer technology and wireless communication technologies are more mature . Wireless networks has become more widely used in people's daily life. For that there is no cable restrictions, wireless networks are more flexible and convenient than traditional network. We can access the network any place where the wireless signal coverage. Wireless network installation, planning and adjustment more convenient, and the scalability has also been greatly improved. However, the transmission rate of wireless network under the influence of channel quality. The main purpose of this paper is to reduce the channel quality changes in the number of conditions on the data transmission rate.From the proposed standard to the finalization, IEEE802.11n has 9 draft and last 7 years. During this period, generated lots of research on the 802.11n, but most concentrated in the physical layer, only a little about the MAC Layer. I have a detailed analysis of the 802.11n MAC layer. Basic on the fixed aggregated frame length of 802.11n, proposed mechanism of the variable greatest aggregation frame length. The mechanism is dynamic adjust the length of the aggregation frame for different channel status. To increase the throughput and improve system efficiency, which network bit error rate has been changed.The variable aggregation frame length mechanism based on channel state classification. First is channel state classification based on bit error rate, each level corresponds to a certain frame length, use the current channel and the packet loss to characterize the current error rate. When the channel bit error rate is constant, it is the same as the 802.11n; when the error rate increased to a certain extent, channel-level drop, corresponding to decreases the length of aggregation frame; when the error rate down to a certain extent, channel-level rise, corresponding to increased the length of aggregation frame.Finally use the network simulation software analysis the variable aggregation frame length mechanism based on channel state classification and 802.11n in different scenes. The results of simulation show that compared with the802.11n, it has optimization of the original protocol by dynamically changing the length of the frame aggregation. Compare with the fixed aggregation frame length, variable aggregation frame length mechanism can effectively enhance the network throughput when the BER changes. Even the channel quality becomes poor, the dynamic maximum aggregate frame length mechanism allows the system still has a smaller packet loss rate, throughput, and also has a big promotion compared with the original protocol.