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Dynamic TDMA slot assignment in ad hoc networks
AINA 2003Akimitsu KANZAKI, Toshiaki UEMUKAI, Takahiro HARA, Shojiro NISHIO
Outline
Related work Proposed protocol Simulation Conclusion Future work
Related work - USAP
USAP: a unifying dynamic distributed multichannel TDMA slot assignment protocol [96 MILCOM]
Related work - USAP
Related work - USAP The first slot in each frame is reserved to tra
nsmit 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 sl
ot s NTi(s) :
nod ei has neighbors which transmit data packets to their neighbors in slot s
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
Related work - USAP multiple access
USAP multiple access: dynamic resource allocation for mobile multihop multichannel wireless networking
[99 MILCOM]
Related work - USAP multiple access
Related work - USAP multiple access
The frame length is a power of 2. The channel utilization is still low.
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
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
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
Proposed protocol – Slot assignment
Selecting an assigned slot Getting an unassigned slot (GU)
Proposed protocol – Slot assignment
Selecting an assigned slot Releasing multiple assigned slots (RMA)
Proposed protocol – Slot assignment
Selecting an assigned slot Doubling the frame (DF)
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 there
Neighbors send REP to confirm
Proposed protocol – Conflict and solution
Proposed protocol – Conflict and solution
Proposed protocol – Conflict and solution
Proposed protocol – Conflict and solution
Simulation - environment
Do not move New node appears at a random
position No new node appears until slot
assignment 2 node to 50 node
Simulation - result
Simulation - result
Simulation - result
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.
Future work
Our protocol can enlarge the frame length, but cannot minify it.