Improving the performance of multi-hop wireless networks using frame aggregation and broadcast for TCP ACKs

Abstract

As data rates supported by the physical layer increase, PHY and especially MAC overheads increasingly dominate the throughput achievable by wireless networks. A promising approach for reducing these overheads is to aggregate a number of frames together into a single transmission. The 802.11n standard uses such an approach for unicast frames. We present the design of a system that can aggregate both unicast and broadcast frames. Further, the system can classify TCP ACK segments so that they can be aggregated with TCP data flowing in the opposite direction. A novel aspect of our work is that we implement and validate our design not through simulation, but rather using our wireless node prototype, Hydra, which supports a high performance PHY based on 802.11n. Our validation shows significant improvements in throughput for each kind of aggregation we support.

Making 802.11 DCF Near-Optimal: Design, Implementation, and Evaluation

“…Some papers proposed new access methods such as dynamic adjustment of CW under 802.11 DCF, e.g., [13] and [14], and there exist the implementation researches along this line, e.g., [15] and [16]. Other work presented efficient aggregation schemes and their real implementations for throughput improvement, e.g., [17] and [18]. Note that most implementations mentioned above individually focused on some specific topologies such as fully connected (FC) case, and do not explicitly consider problematic ones such as HT, IA, and FIM.…”

Packet aggregation based back-pressure scheduling in multi-hop wireless networks

“…Thus multiple IP packets go into the same MAC frame. On the other hand, aggregation which is performed at the MAC layer which is also called as frame aggregation has been experimented in [13,17].…”

Overcoming MAC Overheads Using Packet Size Dependent Channel Widths

“…This preserves the basic fairness capabilities of the 802.11 MAC while taking advantage of higher rates and the overhead reduction of frame aggregation. In [11], the authors propose a cross-layer approach for frame aggregation by which both broadcast and unicast packets can be aggregated into a single frame. The authors use this approach for combining ACK packets (which are considered to be broadcast frames as they do not require link level ACKs) with TCP data packets traveling in the opposite direction.…”