1 research outputs found
New CAP Reduction Mechanisms for IEEE 802.15.4 DSME to Support Fluctuating Traffic in IoT Systems
In 2015, the IEEE 802.15.4 standard was expanded by the Deterministic and
Synchronous Multi-Channel Extension (DSME) to increase reliability, scalability
and energy-efficiency in industrial applications. The extension offers a
TDMA/FDMA-based channel access, where time is divided into two alternating
phases, a contention access period (CAP) and a contention free period (CFP).
During the CAP, transmission slots can be allocated offering an exclusive
access to the shared medium during the CFP. The fraction of CFP's time
slots in a dataframe is a critical value, because it directly influences
agility and throughput. A high throughput demands that the CFP is much longer
than the CAP, i.e., a high value of the fraction , because application
data is only sent during the CFP. High agility is given if the expected waiting
time to send a CAP message is short and that the length of the CAPs are
sufficiently long to accommodate necessary (de)allocations of GTSs, i.e., a low
value of the fraction . Once DSME is configured according to the needs of
an application, the fraction can only assume one of two values and
cannot be changed at run-time. In this paper, we propose two extensions of DSME
that allow to adopt to the current traffic pattern. We show
theoretically and through simulations that the proposed extensions provide a
high degree of responsiveness to traffic fluctuations while keeping the
throughput high.Comment: 21 pages, 14 figure