802.11n wireless LAN performance for mobile devices

摘要

With the increasing adoption of high bandwidth 802.11ac technology by mobile devices in the future, significant improvements performance are anticipated. However, many mobile devices are currently equipped with 802.11n network cards, and a large base of already deployed access points only support 802.11n. We conducted experiments to measure the performance of mobile devices in a 2.4 GHz 802.11n LAN. We used the 2.4 GHz band since most 802.11n networks use this band (802.11n networks can also use the less interference-prone 5 GHz band). Our results indicate that 1) there is high variability in the performance of mobile devices even in an interference-controlled environment with no congestion in the wireline network; and 2) higher performance loss does not always correspond to a higher level of congestion in the wireline network. Packet analysis reveals that the performance variability and performance reduction are primarily due to media access delays and the overhead due to retransmissions on the wireless link. This study shows that regardless of the gigabit capabilities of future 802.11 hardware, inherent characteristics of the shared wireless medium and the 802.11 MAC layer access mechanisms will limit the performance gains of mobile devices even under ideal conditions.