This paper presents a self-organizing MAC protocol framework for distributed sensor networks with arbitrary mesh
topologies. The novelty of the proposed ISOMAC (In-band Self-Organized MAC) protocol lies in its in-band control
mechanism for exchanging TDMA slot information while distributed MAC scheduling. A fixed length bitmap vector is
used in each packet header for exchanging relative slot timing information across immediate and up to 2-hop neighbors.
It is shown that by avoiding explicit timing information exchange, ISOMAC can work without network-wide time
synchronization which can be prohibitive for severely cost-constrained sensor nodes in very large networks. A slotclustering
effect, caused by in-band bitmap constraints, causes ISOMAC to offer better spatial channel reuse compared
to traditional distributed TDMA protocols. ISOMAC employs a partial node wake-up and header-only transmission
strategy to adjust energy expenditure based on the instantaneous nodal data rate. Both analytical and simulation models
have been developed for characterizing the proposed protocol. Results demonstrate that with in-band bitmap vectors of
moderate length, ISOMAC converges reasonably quickly - approximately within 4 to 8 TDMA frame duration. Also, if
the bitmap header duration is restricted within 10% of packet duration, the energy penalty of the in-band information is
quite negligible. It is also shown that ISOMAC can be implemented in the presence of network time synchronization,
although its performance without synchronization is just marginally worse than that with synchronization.