designing routing metrics for wireless mesh networks

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Designing Routing Metrics For

Wireless Mesh Network.Manoj Panditrao Munde, Vinod Jadhav. (Guide).Department of Electronics and Telecommunication, MIT , Pune.(India).

1. [email protected]. [email protected]

Abstract - Designing routing metrics is critical for

the performance in Wireless mesh networks. The

unique characteristics (such as static nodes and

the shared nature of the wireless medium) of

mesh networks, invalidate existing solutions from

both wired and wireless networks and imposeunique requirements on designing routing

metrics for mesh networks. The requirements for

designing routing metrics according to the

characteristics of mesh networks are

investigated. The Network is driven to an

efficient operating point with a certain routing

policies for each node. The wireless backhaul

network is self configuring, instant deployable,

low-cost networking system. In this report , the

wireless backhaul network with routing metric

algorithm is selected with higher throughput

paths and tends to avoid long unreliable links.

Keywords - Wireless mesh networks, Multi-hopWireless, Routing, Optimization method, User coverage.

I. INTRODUCTION.

Wireless Mesh Networks (WMNs) are an

emerging technology that provides adaptive

and flexible wireless Internet connectivity to

mobile users, and WMNs are attracting

significant research and commercial interest.

With the rapid development of communication

technology, multicast communication

applications with multiparty services, e.g.,

video communication, TV conference, distance

learning, computer parallel computation, etc.,

are used in the Internet more and more widely.

Although it has been thoroughly studied in

wired infrastructure and mobile ad hoc

networks for multicast communication, theconstraints inherent to WMNs call for new

efficient routing protocols. During the last few

years, many solutions concerning the multicast

mechanism have been proposed for wireless

networks.

Figure 1. Wireless Mesh Networks.[4]

WMNs have become popular due to its

universal networking capabilities. It

supports a wide range of applications, such

as public safety, emergency response
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communications, intelligent transportation

systems, and community networks etc. It

consists of two types of wireless nodes

namely Mesh Routers and Mesh Clients.

Each node does not operate as a host only

but also acts as a router, which forwards the

packets on behalf of other nodes that may

not be within the direct transmission range

of their destination. WMNs dynamically self

organize and self configure, with the nodes

in the networks automatically, establishing

and maintaining mesh connectivity among

themselves. In wireless mesh networks,

local access points and stationary wireless

mesh routers communicate with each other

and form a backbone network which

forwards the traffic from mobile clients to

the Internet. The backbone of the wireless

mesh network consists of mesh routers,

which connect each other in an ad hoc

manner via wireless links. The presence of

backbone mesh routers and utilization of

multiple channels and interfaces allow the

wireless mesh network to have better

capacity than that of the infrastructure-free

ad hoc network formed by mesh clients

directly. A special type of the mesh routers,

referred to as gateway nodes, is capable of

Internet connection, and other mesh routers

and associated terminal clients have to

access the Internet through the gateway

nodes. In multi-hop wireless networks,

wireless link utilization cannot be used to

characterize the network performance due to

the location dependent contention in the

vicinity area.

The objective of seminar is to maximize the

ratio between flow throughput and its

demand, subject to the schedulability and

fairness constraints with lower end to end

delay.[1]

II. MODEL.[2]

(a). Network model : In wireless mesh

network, local access points aggregate the

traffic from mobile clients that are

associated with them. They communicate

with each other and also with stationary

wireless routers network forming a multi-

hop wireless backbone which forwards the

user traffic to a gateway access point

connecting to the Internet. In our discussion,

local access point, gateway access point, and

mesh routers are collectively called mesh

nodes. A WMN consists of MRs, MCs, and

IGWs. MRs and IGWs form the backbone of

a WMN, covering a large region and

providing service for MCs. MRs

interconnect to each other and forward data

packets by multi-hop fashion. To be more

efficient for packet forwarding, MR is

usually equipped with multiple radios, i.e.,


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interfaces. By operating on different

channels, two radios at a single MR is able

to perform receiving and sending operations

simultaneously.

Figure 2. Network Model.[2]

(b). Energy Model : Although self-powered

MRs are very easy to deploy, the operation

time period of such an MR is constrained by

the energy supply from the batteries. Solar

panel attached to MR can recharge the

batteries to prolong the operation. However,

solar panel is made of limited size and

energy recharge rate is bounded. Consider a

general energy model that the energy

consumption of MR is dominated by its

wireless transmissions and receptions while

neglecting energy consumed in other

operates. Even if the batteries can be

recharged during daytime, a worse energy

situation happens when MR is operated

during nighttime. Conservatively, we

assume that MR has initial energy E0 and

operates without energy recharge. The

energy consumption for sending a bit is

given by:

eT(d) =Eelec +Aampd2,

where;

Eelec = denotes the energy consumption for

basic electronic circuit operations,

d = denotes transmission distance

Aamp = denotes the energy consumed by

amplifier circuit for a bit.

The energy consumption to receive a bit or listen

to the channel for a bit duration is expressed by:

eR =Eelec.

III. ROUTING ALGORITHM.[3]

The load-aware channel assignment

algorithm is not tied to any specific routingalgorithm. It can work with different routing

algorithms. For evaluation purposes, we

explore two different routing algorithms

1. shortest path routing,2. randomized multipath routing.

The shortest path routing is based on

standard Bellman-Ford algorithm with

minimum hop-count metric. The shortest

path here refers to the shortest feasible

path, i.e., a path with sufficient available

bandwidth and least hop-count. The multi-

path routing algorithm attempts to achieve


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loadbalancing by distributing the traffic

between a pair of nodes among multiple

available paths at run time. The exact set of

paths between a communicating node pair is

chosen randomly out of the set of available

paths with sufficient bandwidth.

(a) Optimal Routing.[3]

In light of the above, it is clear that it is

possible to convert the challenge of

maximizing capacity from one where the

dimension of the set of considered

assignments, V, is intractably large, to one

where the size of V and solving (1) is not the

concern, but to where the main challenge is

Step 2 of Algorithm 2, that is, finding

assignments that satisfy (4). It is not hard to

show that (5) is equivalent to the maximum

weighted independent set (MWIS) problem,

which, in the worst-case, is NP-hard.

However, the MWIS problem is not NP-

hard in all cases. For example, in the case of

perfect graphs [8], trees, interval graphs,

claw-free graphs, fork-free graphs, sparse

graphs, and disk graphs, there exists

polynomial algorithms. Also, there exist a

large number of computationally efficient

algorithms for the general case and there are

a large number of approximation schemes.

Computing network capacity :

1. Select an initial set of assignments V

(0), set k = 0.

2. Solve (1) for V = V (k) and compute (k)

and (k), the Lagrange multipliers

associated with constraints (2) and (3),

respectively.

3. Search for an assignment v / V (k)

such that

x (k) R (v, x) > (k).

if such an assignment is found then set V (k

+ 1) = V (k) v, set k = k + 1, and go to

step 3 else if no assignment exists, then stop,

the optimal solution has been found.

end if

4. Remove any redundant assignments inV (k). Then go to Step 1.

(b). Adaptive Routing.[3]

Traditional wireless networks are based onthe presence of an infrastructure providing

wireless access for network connectivity to

wireless terminals. This paradigm has

reigned for many years in cellular networks,

enterprise networks, and variety of

public/private networks. However, a new

paradigm is becoming more and more

popular: peer-to-peer communication, where

wireless nodes communicate with each other

and create ad hoc mesh networks

independently of the presence of any

wireless infrastructures. A MN maintains a


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route table entry for each destination of

interest. Route table information must be

kept even for short-lived routes, such as are

created to temporarily store reverse paths

towards originating RREQs. Each route

table entry contains the following

information:

- Destination IP Address

- Next Hop

- Hop Count (metric)

- Destination Sequence Number

- Valid Destination Sequence Number flag

- Other state and routing flags (e.g., valid,

invalid, repairable, being repaired)

- List of Precursors (active neighbors for this

route)

- Lifetime (expiration or deletion time of the

route)

- Network Interface.

IV. CONCLUSION.

In this report, how to implement routing

algorithm for near-optimally solving the

problem of placement of mesh router nodes

in Wireless Mesh Networks (WMNs) is

considered.

The thorough study gives approach for the

project that a number of client mesh nodes

are a priori distributed in a grid area,

arranged in small cells, and a number of

mesh router nodes are to be deployed in the

area. The shortest path for the packet

transmission is traced through multiple hops

and metrics are being designed for these

route.

REFERENCES.

[1] Roger Karrer , Ashutosh Sabharwal and Edward

Knightly, Enabling Large-Scale Wireless

Broadband : The Case for TAPs, Proceedings of Hot

Nets, Cambridge, MA, 2008.

[2] Weihuang Fu, Xiaoyuan Wang, and Dharma

Agrawal, Characterizing Deployment and

Distribution of Self-powered Mesh Routers in

Wireless Mesh Networks, 28th IEEE International

Performance Computing and Communications

Conference, December 14-16, 2009. Phoenix,

Arizona, USA.

[3] K. Jain, J. Padhye, V. Padmanabhan, and L. Qiu,

Impact of interference on multi-hop wireless

network performance, in Proceedings of ACM

MobiCom, San Diego, CA, September 2003, pp.

6680.

[4]http://www.securedgenetworks.com/secure-edge-

networks-blog/?Tag=Outdoor%20Wireless.
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