Order Matters: Transmission Reordering in Wireless Networks

Abstract

Modern wireless interfaces support a physical layer capability called Message in Message (MIM). Briefly, MIM allows a receiver to disengage from an ongoing reception, and engage onto a stronger incoming signal. Links that otherwise conflict with each other, can be made concurrent with MIM. However, the concurrency is not immediate, and can be achieved only if conflicting links begin transmission in a specific order. The importance of link order is new in wireless research, motivating MIM-aware revisions to link scheduling protocols. This paper identifies the opportunity in MIM-aware reordering, characterizes the optimal improvement in throughput, and designs a link layer protocol to achieve it. Testbed results confirm the performance gains of the proposed system.

Practical Conflict Graphs in the Wild

“…The first category uses conflict graphs that capture interference conditions between link pairs. They build conflict graphs using either a simple distance-based criterion [19], [20] or exhaustive per-link measurements in an active [8], [13]- [17], [24], [49] or passive [18], [50]- [52] manner. These link-based conflict graphs are for indoor WiFi networks where transmission links are known.…”

A distributed message in message aware concurrent transmission protocol in IEEE 802.11 WLANs

“…The authors of [10,11] thoroughly carried out empirical experiments and quantify the threshold that enables MIM captures. Shuffle [12,15] implements MAC layer frame scheduling in order to increase MIM concurrent transmissions. However, Shuffle aggressively disables carrier sensing and carries out consecutive concurrent transmissions causing legacy DCF devices to starve.…”

“…Some of the centralized architectures [15,[26][27][28][29][30] provide the concurrent transmissions through MAC frame scheduling. However, these mechanisms do not take the MIM functionality into account except for Shuffle [15].…”

“…However, these mechanisms do not take the MIM functionality into account except for Shuffle [15]. Therefore, they miss the potential concurrency gains from the MIM opportunities.…”

“…However, in multiple collision domains, MIM enables successful deliveries of otherwise interfering signals. Santhapuri et al [12,15] proposed an MIM-aware centralized packet scheduling algorithm called Shuffle that supports concurrent transmissions from multiple APs. Suppose there are two signals interfering with each other.…”