An Efficient Wireless Mesh
Network A New Architecture
指導教授：許子衡 教授
學生：王志嘉
Introduction (i)
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WMN is composed of Wireless Mesh Routers
(WMR), which offer connectivity to clients by
acting as APs, forming at the same time a selforganized wireless backbone.
The gateway/bridge functionalities in mesh routers
enable the integration of WMNs with various other
networks.
Introduction (ii)
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We use ad hoc networking protocol for WMN in
order to route discovery, table maintenance.
One can use ad hoc networking protocol for WMN
those are defined for ad hoc network only where
all participating node are totally mobile.
That is if you use current ad hoc network protocol
for WMN it will not be able to take advantages of
some fixed node
Existing Architecture of WMN – Overview
(i)
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Wireless mesh network is a mesh of networks.
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It is a network which gives the flexibility to
communicate between different types of networks
like Sensor Network, Wi-Fi Network, and Wi-Max
Network etc. It consists of two types of nodes:
Mesh routers and Mesh Clients.
Existing Architecture of WMN – Mesh
router
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It is similar to the conventional router and has the
same routing functions of the conventional router.
It also includes gateway or bridge or repeater
functions to communicate with different types of
network like Sensor Network,Wi-Fi Network, and
Wi-Max Network.
Mesh routers are minimal mobile. They construct
the backbone of the network for the mesh clients.
They are self-configured, self-healed.
Existing Architecture of WMN – Mesh
client
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It is similar to the conventional client but it is
mobile.It additionally includes routing capabilities
to support mesh network.
It doesn't include gateway or bridge or repeater
functions for the support of communication with
different network.
Existing Architecture of WMN-Architecture
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Three types of architectures exist for WMN. They
are：Infrastructure / Backbone WMN,client
WMN,and hybrid WMN.
Infrastructure / Backbone WMN (i)
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These mesh routers form a backbone or
infrastructure for the mesh clients, as shown in Fig
1.

This backbone supports the access to different
types of network like Sensor Network, Wi-Fi
Network,Wi-Max Network and the Internet
Fig.1
Infrastructure / Backbone WMN (ii)
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Mesh routers can be connected directly to the
Internet. But to communicate with other networks
it must be connected through the access point or
base station of them.
Clients of other networks should connect to the
mesh router through their base station or access
point.
Client WMN
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This network is built only with mesh clients. No
mesh routers are involved here as shown in Fig 2.
They will communicate with same radio
technology. Their communication is peer-to-peer.
Hybrid WMN
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This network is built by meshing the mesh routers
and the mesh clients as shown in Fig 3.
Here mesh routers form the backbone for clients
exactly as in Infrastructure WMN.
The mesh clients have the advantage to be
connected to the internet through the mesh router.
They can also communicate the clients of other
types of networks such as Sensor, Wi-Fl, and WiMax etc through mesh routers.
Fig.3
Proposed Architecture of WMN--Overview

Our proposed architecture is almost same as hybrid
WMN. But here we consider an extra special
purpose mesh router that called master mesh router.
The proposed architecture is shown in Fig. 4.
Fig.4
Proposed Architecture of WMN--Mesh
Router
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Mesh router maintains three types of table such as
client table, routing table and cache table. Client
table contains the information of mesh client.
The routing table contains the best path of this
router to other mesh routers including master mesh
router.
The cache table contains the recent visited paths to
mesh client via this router.
Connectivity Ensure Using Hello Message
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Mesh routers send Hello message within specified
time period to ensure connectivity. But all mesh
routers don't send Hello message. Particular mesh
routers only send and check the connectivity
To determine the router head, mesh routers execute
an algorithm 'Router Head Selection Algorithm'.
Connectivity Ensure Using Hello Message
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The basic function of that algorithm is as follows：
1.
2.
It fast selects a mesh router as a router head whose
maximum number of adjacent mesh router and
constructs a cell with its adjacent routers as shown in
Fig.5
Select a gateway router among the adjacent of router
head whose maximum number of adjacent and
minimum number of adjacent is member of existing
cell.
Fig.5
Connectivity Ensure Using Hello Message
3.
4.
Now the gateway router selects a adjacent router as
router head whose maximum number of adjacent and
minimum number of adjacent is member of existing
cell.
If an adjacent of gateway has no adjacent and is not
member of any cell then gateway takes special care of
that router.
Connectivity Ensure Using Hello Message
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After selecting router head and gateway router,
only router heads send Hello message to its
neighbor.
If a mesh router is shutdown then router head
detects it or if a router head is shutdown then
gateway router detects it. So connectivity is
ensured here.
Tables Maintenance
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The routing table holds the information of other
mesh router includes master mesh router.
The format of routing table is shown in Fig.6.
Two type of path to access a mesh router are store
in the routing table. Strong Path is only use the
strong link. On the other hand the weak path uses
either strong link or weak link or combination of
both.
Fig.7. is shown the strong path and weak path.
Fig.6
Fig.7
Reduce network traffic
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To ensure connectivity router head and gateway
router only send Hello message within specified
time period. But other mesh routers don't send
Hello message. Using this technique the amount of
network traffic can be reduced.
When mesh router want to use that link but it's not
valid it just update its routing table and uses strong
path.
Drawbacks
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The disadvantage of having a router head scheme
is that frequent router head changes can adversely
affect routing performance since mesh router are
busy in router head selection rather than packet
relaying.
Mesh Client
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The mesh clients are the end user in the network.
A mesh client stores information about its neighbor
in this table.
Mesh clients stay on the common zone of one
more mesh router. In this circumstance, it stores
only one mesh router's information that is how to
access that mesh router.
Route Maintenance
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A client wants t o join this network. It fast
broadcasts the Update message.
Mesh router receives Update message and send
unicast Update message to master router that a
mesh client join.
The other mesh clients receive Update message
and update their neighbor table. If a mesh client is
down or changes its position then mesh router and
mesh client will detect that by using Hello message
and they will change their corresponding table.
Route Maintenance
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Now a client of a mesh router wants to access
another client. The wanted client may stay its
neighbor or the same mesh router but not neighbor
or different mesh router.
Otherwise it sends Route Request to mesh router.
If not available then mesh router send Route
Request to master mesh router. Master mesh router
also check its client table if the require client is
available then it sent to mesh router Route Reply.
Conclusion
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According to our proposal this new architecture of
WMN is efficient one. It has reduced overhead
caused by route maintenance, route discovery.
Network traffic reduces dramatically than current
status.
We can get relive from using ad hoc network
routing protocol that is used now a day for WMN