Wireless Mesh Networks/Mesh network basics

 Wireless Mesh Networks 

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Acknowledgements — Introduction — Mesh network basics — History Highlights — Motivation — Economics — Politics — Social Impact — Regulatory — Taxonomy of Mesh Types — Design Parameters — How many radios? — Transport — Access — RF concerns — What layers does it run on? — Topology Control — Mobility Handoffs — Applications — Content — Operations — Accounting and Billing — Management — Getting Power to the Node — Survey Tools — Planning Tools — Mounting Options — Testing Tools — Meshes you can build — Conclusion — Applicable Standards — Known Deployments — Mesh Timeline — Mesh Network Vendors — Bibliography — Glossary — Index

Mesh network basics

What is a Mesh Network?

A mesh network is a multiple path and multiple hop area wide network that are ideal for outdoor deployment. The mesh network consists of wireless networking devices (known as nodes)connecting within the range of the network nodes. Hence, it will form a decentralized networking as each node will only need to extend its own wireless range up to next node only. Each nodes are consistently communicating with each other in the local mesh network and are responsible for acting as a gateway for the packets to travel inside the mesh network.

A wireless mesh network have 3 characteristic of autonomic system which are

• Self forming / self organizing
• Self healing
• Self optimization
• Multi hop

Self-forming / Self-organizing

New nodes joining the mesh network are transparently supported because meshing functions such as neighbours discovery and topology learning are implemented. Wireless routers rapidly detect the presence of new paths, thus enhancing the overall performance and coverage

The picture above shows the mesh networking self forming ability.

[1] A new node joins the mesh network
[2] Surrounding node are alerted to the new node presence and configuring on the fly to provide optimized routing for the packets
[3] The new node are accepted in the mesh network

Self-healing

A node may leave a mesh network due to unexpected circumstances such as failure in the networking devices, natural disaster/man made disaster and such.Therefore ,the mesh network are inherently designed to be more robust and resilient. There are many ways to do this such as make it a multi-path for packets to travel from one nodes to another (the amount of connections between 2 nodes is 2 or more) , decentralized connections and redundancy.

The picture above shows the mesh networking self healing ability

[1] One of the nodes in the mesh network are showing intermittent failures
[2] Surrounding nodes connected to the intermittent failing nodes are re-configuring to respond to the failing node
[3] The failing node when offline but the mesh network is still operating without downtime

Self Optimization

The mesh network have the self optimization to enlarge the mesh coverage as large as possible, to minimizes the interferences and also to maximizes the bandwidth capacity of the mesh network.

Multi-hop

Multi-hop connectivity allows several devices to access the network at once by relying on other mesh nodes without affecting the overall network performance. It will guarantees larger coverage zones and an enhancement of the network capacity. In fact, line-of-sight constraint no longer matters because the intermediate nodes relay the information to their neighbors on short wireless links using a reduced power transmission.

The picture above shows the multi-hop of mesh network in progress.
[1] Node A want to access to the node D
[2] Node A sends wireless transmission links to nearby nodes
[3] Node B & node E forming link with node A
[4] Node E already found the node D forming mesh connection A-E-D
[5] Node B is still searching for node D but find node C instead
[6]Node C already found the node D forming mesh connection A-B-C-D

Mesh vs. Point to Multi-point

Reliability

In a classic wireless network, each node monitors that path between itself and an additional node. These networks are configured in a hierarchical fashion that ensures that each node uses a single connection path. The drawback to this approach is its lack of failure protection. If a node fails, the dedicated link is lost and the endpoint is unreachable until service is restored.

The establishment of multiple connection paths is a logical answer to this problem. Unfortunately, classic nodes lack the intelligent technology to select from alternate transmission paths.

Developers studied the idea of adding intelligence to each node to solve this problem. Such intelligence would track each available communication path and would logically select the best route. Added together, the multiplicity of nodes would create a mesh. This mesh would eliminate single points of failure. If one link went down,other network nodes would be alerted and could select an alternative node path. The design's self-healing nature would ensure that the network continued to operate. User access would be maintained as would productivity levels.

Today, the concept of intelligent mesh networks is a reality. Mesh is an increasingly applied network topology as researchers improve and enhance it, and businesses deploy and utilize it. Mesh has become the technology of choice for applications as diverse as securing military perimeters to regulating product flow down factory assembly lines to facilitating the intelligent navigation of one's morning commute.