Bandwidth Balancing in Multi-Channel IEEE 802.16 Wireless Mesh networks

Claudio Cicconetti, Ian F. AkyildizSchool of Electrical and Computer Engineering

Georgia Institute of Technology, Atlanta

Luciano LenziniDipartimento di Ingegneria dell’Informazione

University of Pisa

IEEE INFOCOM 2007

Outline

Introduction Fair end-to-end bandwidth allocation Performance Evaluation Conclusion

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

Introduction_802.16(2)

The frame in mesh mode consists of a control subframe and a data subframe

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<slot,frame,channel>Confirm

Introduction_802.16(4)

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

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

Fair end-to-end bandwidth allocationNumber of

bytes that X has notified to YNumber of

bytes that X has confirmed to YNumber of bytes awaiting transmission at

X toward YNumber of bytes that Queue i could’t consume

Number of bytes that Y has

notified to XNumber 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

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

Fair end-to-end bandwidth allocation

The grant horizon ,at time t , in units of frame ,can be expressed as

Request

<slot,frame,channel>

t t+ t+

Fair end-to-end bandwidth allocation

Fair end-to-end bandwidth allocation

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

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:

Simulation _(2)

Simulation _(3)

Simulation _(4)

Simulation _(5)

Conclusion

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