Soft-TDMAC: Software TDMA-Based MAC Over Commodity 802.11 Hardware

The authors design and implement Soft-TDMAC, a software Time Division Multiple Access (TDMA) based MAC protocol, running over commodity 802.11 hardware. Soft-TDMAC has a synchronization mechanism, which synchronizes all pairs of network clocks to within microseconds of each other. Building on pairwise synchronization, Soft-TDMAC achieves network wide synchronization. With, out-of-band, network wide synchronization Soft-TDMAC can schedule arbitrary TDMA transmission patterns. They summarize hundreds of hours of testing Soft-TDMAC on a multi-hop testbed. Their experimental results show that Soft-TDMAC synchronizes multi-hop networks to within a few microsecond sized TDMA slots.