• The KIPS Transactions:PartC
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• v.15C no.5
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• pp.419-428
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• 2008

IEEE 802.15.4 reserves transmission time to support real-time transport by sending GTS request packets to the PAN coordinator in advance. This paper introduces GTS-FAT technique to reduce the reservation time by giving a higher sending priority to GTS request packets than data packets. Differently from the conventional scheme where these two kinds of packets share a single transmission queue, GTS-FAT scheme allocates two queues with two different contention window sizes like IEEE 802.11e. This paper also proposes an analytical GTS delay model by combining the two legacy models for 802.15.4 and 802.11e to accurately predict the GTS-FAT delay over a given network topology. Our analysis shows that GTS-FAT reduces GTS service delay by up to 50% at the expense of the data delay by only up to 6.1% when GTS request packets four times outnumber data packets.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.9
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• pp.19-28
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• 2010

The GTS(Guaranteed Time Slot) of the IEEE 802.15.4 standard, which is the contention free access mechanism, is used for low-latency applications or applications requiring specific data bandwidth. But it has some problems such as delay of service due to FIFS(First In First Service) scheduling. In this paper, we proposes a weight based GTS allocation scheme for fair queuing in IEEE 802.15.4 LR-WPAN. The proposed scheme uses a weight that formed by how much more weight we give to the recent history than to the older history for a new GTS allocation. This scheme reduces service delay time and also guarantees transmission simultaneously within a limited time. The results of the performance analysis shows that our approach improves the performance as compared to the native explicit allocation mechanism defined in the IEEE 802.15.4 standard.