Source: http://www.radioresourcemag.com/only...

O N L I N E E X C L U S I V E

Three Generations of Mesh Networks
July 09, 2008

By Byron Henderson

The key to successful mining installations is the ability to provide high performance over a large number of hops. Mesh networks have evolved, and the third generation of products offers significantly higher performance and reliability. Following is an overview of mesh networks at each generation of products.

First Generation. In single-radio first-generation wireless mesh products, a single radio provides both service (connection to individual user devices) and backhaul (links across the mesh to the wired or fiber connection), so wireless congestion and contention takes place at every node. Users soon discovered that only two radio hops were possible between connections to the wired or fiber Ethernet.

Both the client and backhaul share the same radio, subject to RF interference from other radios operating on the same or adjacent frequencies.

Second Generation. Second-generation mesh technology places two radios in each node, typically combining an 802.11b/g service radio with an 802.11a backhaul radio. With heavy user demand, there is still significant contention and congestion on the backhaul links. This limits the number of radio hops to typically three or less before another wired or fiber Ethernet connection is needed.

This architecture segments interference from client radios and the backhaul. But all backhaul radios share the same frequency, subject to RF interference from others operating on the same or adjacent frequencies.

Third Generation. MeshDynamics' patented and patent-pending third-generation solutions begin by providing two backhaul radios in each node. To overcome the problems of congestion and contention, one radio creates a link to its upstream, nearer the wired source or root, node. Another radio creates a link downstream to the next neighbor node.

Each node may send and receive simultaneously to its upstream and downstream neighbors, unlike most competitive solutions that must continually turn around between sending and receiving upstream and downstream. Because each link is managed independently, the available channels may be re-used across the network. This expands the available spectrum, increasing performance of the network 50 times or more compared with traditional wireless mesh solutions.

This architecture segments the interference from client radios and the backhaul. Further each backhaul is split into two radios, operating on two different channels. RF interference in one segment of the network is automatically addressed by dynamic channel management technology.

Byron Henderson is vice president, marketing for MeshDynamics, which serves cutomers in many market areas: mining and industrial sites, defense, transportation, public safety and municipal networking. E-mail comments to editor@RRMediaGroup.com.

Mesh Networks Snapshot Survey

In a survey of MissionCritical Communications readers, we found that about 18 percent of respondents currently use mesh networks, and another 18 percent plan to implement mesh networks in the next two years. Local/state public safety is the industry that most uses mesh networks, followed by federal and homeland-security agencies and utilities. Video surveillance and Internet access are the main applications for mesh networks, followed by mobile database access and mobile ad-hoc networking.