1. Nov. 2 th, 2010 Hyung Wook Cho (chohw@ece.skku.ac.kr) Utilization-Aware Dynamic GTS Allocation Scheme in IEEE 802.15.4 APCC 2010

2. - 2 / 12 - Contents Introduction Related Works Proposed Schemes GTS Allocation Management State Management Performance Evaluation Conclusion

3. - 3 / 12 - Introduction IEEE 802.15.4 Specification of MAC sub-layer and physical layer for LR-WPAN MAC sub-layer Being classified into beacon-enabled and non beacon-enabled modes Nonbeacon-enabled mode : Unslotted carrier sense multiple access with collision avoidance (CSMA/CA) Beacon-enabled mode : Slotted CSMA/CA, GTS (guaranteed time slot) mechanism An example of superframe in beacon-enabled mode

4. - 4 / 12 - Related Works GTS mechanism Without contention, a device can transmit their frames The maximum number of GTSs which can be allocated to devices in each superframe is limited to seven GTS allocation Based on GTS allocation request command transmitted by devices GTS deallocation A request of devices PAN coordinator decision : expiration timer 2*k

5. - 5 / 12 - GTS Allocation Management Utilization of ith device in nth superframe Priority of ith device for GTS allocation in nth superframe Weighted exponential moving average with weight α PAN coordinator dynamically allocates GTSs to devices in the descending order of their priorities for next superframe The top seven devices will be assigned GTSs Exceptional case A device newly transmits GTS allocation request command

6. - 6 / 12 - State Management PAN coordinator classifies devices into three states and maintains states of devices for priority management Non-GTS state : The device does not require GTS GTS-occupation state : The device has priority and is updated priority GTS-desire state : The device has priority for GTS allocation State transition diagram of each device

7. - 7 / 12 - Performance Evaluation Simulation parameters Service arrival : poisson proccess ParametersValue Network topologyStar topology Simulation duration20,000 BIs Transmission rate250kbps SO3 Buffer size of each device100 bytes λ arrival 0.1 times/sec Average service duration100 sec α0.7

8. - 8 / 12 - Performance Evaluation Varying the number of device(N) (BO=5, packet size=10bytes)

9. - 9 / 12 - Performance Evaluation Varying the packet size (BO=5, N=20)

10. - 10 / 12 - Conclusion Our main objective To increase utilization of overall network To minimize latency for frame transmission We proposed Utilization aware dynamic GTS allocation scheme State management of each device Priority based on utilization of GTS Through simulation results, we confirm our proposed scheme has better performance than conventional scheme Throughput Average packet waiting time

11. - 11 / 12 - chohw@ece.skku.ac.kr Thank you!