An empirical evaluation of bufferbloat in IEEE 802.11n wireless networks

Abstract—In this paper, we analyze the impact of large, persistently-full buffers (‘bufferbloat’) on various network dy-namics in IEEE 802.11n wireless networks. The bufferbloat prob-lem has mostly been studied in the context of wired networks. We study the impact of bufferbloat on a variety of wireless network topologies, including wireless LAN (WLAN) and multi-hop wireless networks, with varying wireless link rates. Our results show that a single FTP transfer between two Linux wireless hosts can saturate the buffers in the network stack, leading to RTT delays exceeding 4.5 s in multi-hop configurations. We show that Aggregate MAC Protocol Data Unit (A-MPDU) MAC-layer frame aggregation can be used to reduce RTT delays while simultaneously increasing network throughput. However, additional measures may still be required to meet the constraints of real-time flows (such as VoIP). Our experiments show that large buffers can deteriorate the fairness in rate allocation in parking lot based multi-hop networks. Index Terms—Bufferbloat, IEEE 802.11n, Frame Aggregation, A-MPDU, TC