Toronto Networking Seminar

Organized by Department of Computer Science and Department of Electrical and Computer Engineering, University of Toronto

Soft-TDMAC: A Software-based 802.11 Overlay TDMA MAC Protocol with Microsecond Synchronization

Petar Djukic
Department of Systems and Computer Engineering
Carleton University


Friday, May 7, 2pm
Location: BAB024 (Bahen Centre Basement)


We implement a new software-based multi-hop TDMA MAC protocol  (Soft-TDMAC) with microsecond synchronization using a novel system interface for development of 802.11 overlay TDMA MAC protocols  (SySI-MAC). SySI-MAC provides a simple, kernel independent, message based interface for overlay MAC protocol implementations to schedule transmissions, send packets, and receive packets. The key feature of  SySI-MAC is that it provides near deterministic timer scheduling and transmission times, which allows for implementation of highly synchronized TDMA MAC protocols. Building on SySI-MAC's predictable  transmission times we implement Soft-TDMAC, a software based 802.11 overlay multi-hop TDMA MAC protocol. 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 tight network-wide synchronization. With network-wide synchronization independent of data transmissions, Soft-TDMAC can schedule arbitrary TDMA transmission patterns. For example, Soft-TDMAC enables schedules that decrease end-to-end delay and take end-to-end rate demands into account. We summarize hundreds of  hours of testing Soft-TDMAC on a multi-hop test-bed, showing the synchronization capabilities of the protocol and the benefits of flexible scheduling.


Petar Djukic received B.A.Sc., M.A.Sc. and Ph.D. degrees from the University of Toronto in 1999, 2002 and 2007, respectively. From 2008 to 2010 he was a postdoctoral researcher at the Department of Systems and Computer Engineering, Carleton University, Ottawa, Canada. From 2007 to 2008 he was a postdoctoral researcher at the Department of Computer Science, University of California, Davis. From 1999 to 2001 he worked as a software designer in Ottawa, Canada. His research interests are in wireless multi-hop scheduling, radio access network resource management, and testbed implementations of new wireless MAC protocols.

Host of Talk:

Shahrokh Valaee (