1. Dynamic TDMA slot assignment in ad hoc networks AINA 2003 Akimitsu KANZAKI, Toshiaki UEMUKAI, Takahiro HARA, Shojiro NISHIO

2. Outline Related work Proposed protocol Simulation Conclusion Future work

3. Related work - USAP USAP: a unifying dynamic distributed multichannel TDMA slot assignment protocol [96 MILCOM]

4. Related work - USAP

5. The first slot in each frame is reserved to transmit control packet (NMOP) NMOP STi(s) : node i transmits a data packet to its neighbors in slot s SRi(s) : i receives a data packet from one of its neighbors in slot s NTi(s) : nod ei has neighbors which transmit data packets to their neighbors in slot s

6. Related work - USAP When a new node joins the network, it firstly collects NMOPs by listening the network channel for a cycle All nodes in the network, N and M should be large enough As a result, the channel utilization usually becomes low

7. Related work - USAP multiple access USAP multiple access: dynamic resource allocation for mobile multihop multichannel wireless networking [99 MILCOM]

8. Related work - USAP multiple access

9. The frame length is a power of 2. The channel utilization is still low.

10. Proposed protocol – frame format The frame length in our protocol is set as a power of 2. The first slot in the frame is reserved for new nodes to transmit control packets. Data packet Frame length

11. Proposed protocol – Slot assignment Requesting the information on slot assignment in the contention area Listen the channel for a certain period Send REQ packet in the first slot next frame Neighbors send its and its neighbor slot information in its assigned slot by INF packet Frame length Slot information

12. Proposed protocol – Slot assignment Setting the frame length and grasping slot assignment The new node adopts the maximum frame length among all nodes in the contention area

13. Proposed protocol – Slot assignment Selecting an assigned slot Getting an unassigned slot (GU)

14. Proposed protocol – Slot assignment Selecting an assigned slot Releasing multiple assigned slots (RMA)

15. Proposed protocol – Slot assignment Selecting an assigned slot Doubling the frame (DF)

16. Proposed protocol – Slot assignment Announcement and Confirmation After selecting a slot assigned to itself, the new node sends a SUG to its neighbors which contains information on the frame length and the assigned slot. When a neighbor receives this packet, it updates its slot assignment information. If the frame length of the neighbor is different from that in SUG, its frame length is changed in the same way in therethere Neighbors send REP to confirm

17. Proposed protocol – Conflict and solution

21. Simulation - environment Do not move New node appears at a random position No new node appears until slot assignment 2 node to 50 node

22. Simulation - result

25. Conclusion Proposed a TDMA slot assignment protocol to improve the channel utilization. Avoids the increase of unassigned slots by minimizing the frame length of each node.

26. Future work Our protocol can enlarge the frame length, but cannot minify it.