An empirical study on achievable throughputs of IEEE 802.11n devices

The empirical performance studies on the emerging IEEE 802.11n technology by an independent and vendor-neutral party have not really been explored. In this paper, we conduct performance measurements for the IEEE 802.11n network using a mixture of commercially available IEEE 802.11n devices from various manufacturers. With the same standard 20-MHz channel width configuration, the results demonstrate that IEEE 802.11n significantly outperforms the IEEE 802.11g network. The performance improvements of IEEE 802.11n are measured to be roughly about 85% for the downlink UDP traffic, 68% for the downlink TCP traffic, 50% for the uplink UDP traffic, and 90% for the uplink TCP traffic. We also observe that the UDP throughputs are largely imbalanced for the uplink and downlink traffics in most test networks, while the downlink and uplink TCP throughput results are quite balanced for all test networks. In addition, the 40-MHz channel configurations only provide marginal performance improvements. Unlike other existing work, here we also capture and analyze the IEEE 802.11n packets transferred during the performance tests in order to technically explain the measured performance results. It is observed that when the frame aggregation and block acknowledgement mechanisms are utilized, the superior performance results are achieved. However, the decisions on how and when to use these mechanisms are very hardware dependent.