1. Bandwidth Balancing in Multi- Channel IEEE 802.16 Wireless Mesh networks Claudio Cicconetti, Ian F. Akyildiz School of Electrical and Computer Engineering Georgia Institute of Technology, Atlanta Luciano Lenzini Dipartimento di Ingegneria dell’Informazione University of Pisa IEEE INFOCOM 2007

2. Outline  Introduction  Fair end-to-end bandwidth allocation  Performance Evaluation  Conclusion

3. Introduction_ 802.16(1)  There are two coordination mode in WiMax mesh network Centralized Distributed  In the distributed mode,SSs can communicate to their neighbors directly

4. Introduction_ 802.16(2)  The frame in mesh mode consists of a control subframe and a data subframe

5. Introduction_ 802.16(3)  The amount of bytes conveyed by a slot depends on the Modulation and Coding Scheme (MCS)  Every node dynamically adapts the MCS from neighbor to neighbor  Data transmission in MSH-DSCH is coordinated by the following procedure Requester asks a neighbor node, granter, to allocate some bandwidth the granter advertises a set of slots as ‘granted’ to the requester the requester confirms that it will actually use that set of slots (or part thereof) to transmit data Request Confirm

6. Introduction_ 802.16(4)

7. Fair end-to-end bandwidth allocation  There are some assumptions The network topology is fixed Each node has a single radio interface Each node can dynamically switch to one channel at a time  The “ fairness ” is a desirable property for any MAC protocol

8. Fair end-to-end bandwidth allocation  Define 1 (traffic flow): A traffic flow is a stream of IP datagrams from a source to a destination node

9. Fair end-to-end bandwidth allocation Number of bytes that X has notified to Y Number of bytes that X has confirmed to Y Number of bytes awaiting transmission at X toward Y Number of bytes that Queue i could ’ t consume Number of bytes that Y has notified to X Number of bytes that X has granted to Y The set of all active traffic flows served by this node An indicator function which equals 1 if j is under at queue i

10. The number of bytes that queue I could ’ t consume granting queue is inactive, since X granted the byte requested by Y Fair end-to-end bandwidth allocation the requesting queue is inactive The request demands can ’ t fulfilled by the granter

11. Fair end-to-end bandwidth allocation  The grant horizon,at time t, in units of frame,can be expressed as Request tt+

12. Fair end-to-end bandwidth allocation

14. Simulation _ Environment  Simulation is implement in the ns2 network simulator  Channel bandwidth is 10 MHZ  Frame duration is 4 ms  Nodes employ the 16-QAM-1/2 MCS  Each traffic flow had a separate 100kB buffer

15. Simulation _ (1)  A fair index  n denotes the number of traffic flow  Xi the throughput of the i-th traffic flow Flow 1 2 Flow 2 2 Flow 3 2 (2+2+2)^2 / 3* (4+4+4) =36/36=1 EX:

16. Simulation _ (2)

17. Simulation _ (3)

18. Simulation _ (4)

19. Simulation _ (5)

20. Conclusion  Presented a distributed algorithm for bandwidth (FEBA) balancing in multi-channel IEEE 802.16 WMNs