Wirless mesh networks

Can be considered as a type of Adhoc network.But seeing the technical complexities involved and various topologies involved , WMN can be rather considered as a super set of Adhoc Networks.
The next few posts will be my attempt (in process of learning) to analyse and understand the differences between these and various other needed changes for WMN. I would be mainly refering to a technical paper : Wireless Mesh networks a survey by Ian F.Akyildiz, Xudong Wang, Weilin Wang. This paper is considered as a bible for upcoming research articles.
Apart from that, I will also make an attempt to elaborate few concepts. Again these concepts are what I see them as , if you have different ideas or suggestion or corrections to them you are all welcome to post a comment, after all we are in process of knowing things in a right way and correcting our perceptions. 😀.

WIRELESS NETWORKS TYPES:
Firstly, talking about Wireless Mesh Networks, you all might be very aware of wireless networks.
Wireless Networks are based on the IEEE standard 802.11b.The wireless networks can be considered as two subgroups 1.Infrastructure Wireless networks and 2.Adhoc Networks (Ref doc:IEEE std 802.11 standard for information technology). Infrastructure networks are day to day networks what we see including WiFi, Wi Max, MAN etc etc. Adhoc networks are not so frequent networks what we see .

TOPOLOGICAL DIFFERENCE:
Infrastructure wireless networks can be defined better using the words BSS(basic service set) . Each BSS generally consists of a AN and a set of clients. This AN acts as a Server for that specific BSA or the cell.
[​IMG]
Picture ref:The Best Damn Cisco Internetworking Book
Where as in Adhoc network , a Access point is NOT needed. Any wireless device capable of acting like a router can be an integral part of a Adhoc network. It is very similar to peer-to-peer computer network.
[​IMG]
Picture ref:The Best Damn Cisco Internetworking Book
Now as we know the general topology of Adhoc network, lets see the topology of Wireless Mesh network.The topology can be classified as of three different types:
1.Client topology
2.Infrastructure topology
3.Hybrid topology

Client Topology:
Client topology is very similar to Adhoc networks , they don't have a Access node, they don't have a backbone network , they are just harmonious amongst them selves. The clients can be a mobile phone , a laptop,GPS anything.When a client needs to send a packet to a another client , the packet is hopped through many of the intermediate clients.
[​IMG]
since the nature of the network is Adhoc, the clients can go down at any time hence leading to recalculation. Question what might arise here is : if the packet is midway between the source and destination and a client goes down how is the route calculated? does the packet needs a retransmission from the source or the current node which is transmitting takes care of the next node without bothering the original source?Also how is the route calculated on the first instance. I will keep these open issues as they are and try to discuss them in the routing methods in next coming posts.One more point would be, what if the clients are on protocols, will they still be able to be a component of mesh network? and the clients need to be talking on same radio technology as well.Apart from all the above thoughts, what would be the power requirements of such devices?

Infrastructure backbone network:
A combination wired and unwired connections.The basic topology consists of three level layers.
[​IMG]
reference:above mentioned paper work
s can be seen, the mesh routers form the basic backbone of this topology. Though as a basic of Adhoc networks though the clients can as well act as routers, they don't generally tend to fulfill the gateway functionality.Also, the mesh routers layer is connected to internet default through Ethernet. As also can be seen from diagram the mesh layer connects can seen as to be integrating various types of networks.The mesh router uses two radios to communicate, one radio to communicate with other routers generally directional antennas and the other radio to communicate with the immediate clients and networks.The clients can access internet either through direct communication with the WM router or can talk to related AP. As far as I can see or my knowledge is limited, i am not quite sure how the mesh routers are configured to handle data from various networks and as well how mobility will be managed when the clients move intranet or to a different network.Slowly as we progress to learn, i am sure we will come up with relevant answers for the open issues.
The third and last type of network what I would discuss is Hybrid network
3.Hybrid Network.
the combination of client WMN and infrastructure networks .
The client networks can access internet either through the mesh routers or via hopping through the mesh routers. Unlike infrastructure WMN, its all client network here .Open issue here would be the backward compatibiltiy with the routers to older generation wireless cleints.
[​IMG]

Next discussion:
>applications
>characteristics

P.S:The same post has been put up in my blog as well, any comments on that post , i will paste them here.
Meanwhile, try discussing the topic here. I might as well start discussing about the routing techinques as well, as thats the part which interests me much! but I would prefer to go through it slowly.

Replies

  • gohm
    gohm
    Durga, yet another well made insightful post. My first thought would be to know what some examples of uses of these are, however that might be in your next subject, applications.
  • durga ch
    durga ch
    Yup! Therer are uinnumerable applications, one classis example would be WAVE(wireless access to vehicular environments.I will try to explain the purpose in my next post and try to trigger some interest amonsgt CEans Afterall ,Reading without knowing why you are reading is so waste 😛
  • Ashraf HZ
    Ashraf HZ
    Useful info. Keep it up 😀
  • seraulu1
    seraulu1

You are reading an archived discussion.

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