Applying Data Fragmentation in IEEE 802.15.4: Modeling and Analysis under Unsaturated Traffic.

The IEEE 802.15.4 standard, which is developed for low rate applications, offers low latency and energy consumption for wireless sensor networks. The use of the standardized slotted Carrier Sense Multiple Access (CSMA/CA), as a channel access mechanism, can, however, lead to a wastage of the bandwidth utilization and an additional transmission delay. This drawback is mainly caused by deferred transmission in the CSMA/CA algorithm at the end of the superframe, when there is not sufficient time to complete the frame transmission. We propose in this paper to fragment a data frame into a short frame and attempt its transmission in the current frame and transmit the remaining frame in the next superframe. The data fragmentation mechanism is modeled using a Markov chains. A non-saturated traffic and acknowledgement transmission are considered in our analysis. The analytical results of the normalized throughput demonstrate the improvement of the bandwidth occupation when using the proposed data fragmentation mechanism in the IEEE 802.15.4 slotted CSMA/CA protocol.