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Issue No. 03 - March (2012 vol. 11)
ISSN: 1536-1233
pp: 478-491
P. Mohapatra , Dept. of Comput. Sci., Univ. of California at Davis, Davis, CA, USA
P. Djukic , Meshlntelligence, Inc., Ottawa, ON, Canada
ABSTRACT
We implement a new software-based multihop 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 kernel independent message-based interface for scheduling transmissions and sending and receiving 802.11 packets. The key feature of SySI-MAC is that it provides near deterministic timers 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 multihop 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 allows 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 multihop testbed, showing the synchronization capabilities of the protocol and the benefits of flexible scheduling.
INDEX TERMS
wireless LAN, access protocols, synchronisation, time division multiple access, end-to-end rate demands, soft-TDMAC, software-based 802.11, overlay TDMA MAC, microsecond synchronization, software-based multihop TDMA MAC protocol, 802.11 packets, TDMA transmission patterns, end-to-end delay, Synchronization, Time division multiple access, Spread spectrum communciation, IEEE 802.11 Standards, Media Access Protocol, Schedules, Media Access Protocols, network synchronization., Multihop TDMA MAC, 802.11 overlay MAC
CITATION
P. Mohapatra, P. Djukic, "Soft-TDMAC: A Software-Based 802.11 Overlay TDMA MAC with Microsecond Synchronization", IEEE Transactions on Mobile Computing, vol. 11, no. , pp. 478-491, March 2012, doi:10.1109/TMC.2011.56
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