Mesh Without Wires

April 26, 2010

When Wireless Video Mesh is Not ‘True’ Mesh (But Better)

Filed under: Physical Security,Public Safety Wireless — kseniacoffman @ 11:03 am
Tags: , ,

The title is a play on words, but it simply means that a ‘fully-meshed’ network design may not fit the topology or the customer requirements. But the unique capabilities of Firetide‘s mesh allow the network to meet the project performance expectations.

This post follows the theme of wireless mesh network design. (For a broader discussion, see: Network Design Considerations for Wireless Video Surveillance). To illustrate and expand on why flexibility of mesh topology is important for video surveillance, consider this: mesh is a superset of point-to-point and point-to-multipoint systems. In addition, the distributed intelligence of the mesh and transparent switching/routing within it enable performance that other systems cannot achieve. Two examples below:

Nested point-to-point mesh design

Firetide nested PtP mesh design

Firetide nested PtP mesh design (Click on image for full-size view)

Even though the design uses point-to-point and point-to-multipoint approach, many of the links are ‘nested’ (with some nodes acting as repeaters), which is only possible with mesh gear. You could deploy point-to-point (maybe) but you’d have to deploy a base station at each nesting locations, which is expensive, and also take a hit in performance as you are switching from subscriber units to base stations. Instead, the ‘nesting’ nodes are dual-radio, so they are able to communicate in both directions without throughput degradation.

Also note frequency re-use as indicated by green lines, showing the same frequency being used. This is possible since mesh in street level, and therefore the signals on the same frequency are isolated from each other and are non-interfering.

The two physical meshes you see on the image are logically a single mesh (illustrating our concept of a distributed wireless Ethernet switch), and as such, have a single IP address for the entire mesh. The two head nodes on the main building are interconnected via in-building LAN network.

What you are seeing is a real-life example of a high-performance mesh. This nested design was the best option given the site’s topology.

Linear loop mesh design

Firetide linear loop mesh design (Click on image for larger view)

Firetide linear loop mesh design (Click on image for larger view)

This is an example of a redundant linear mesh, with redundancy achieved through the completion of the circle. If one of the links is broken, the mesh will automatically re-route the traffic without any dropped packets or added latency.

The advantages of using mesh equipment vs a collection of point-to-point links in this situation are:

  • All of the links can be  system can be managed through the same network management interface
  • You get system-wide diagnostics and alerts
  • Less real estate and power required at each location (one radio node, instead of two separate boxes)
  • Latency and jitter is minimized with intra-radio switching

For more posts on wireless network design for high-performance applications, see:

By: Ksenia Coffman – Connect with me on Twitter or LinkedIn.

3 Comments »

  1. Nice article with some great examples on the flexibility of “Mesh Node” radios units. The first example looks almost more like a blend of point to point and point to multipoint? I’m assuming you used dual radio units?

    Sometimes I think examples like the ones shown here are better examples on deployments than actual mesh ones! The best feature of mesh radios (that support configurations like the ones shown in your article) are that they are flexible in their configuration, whether as mesh, point to point, point to point daisy chaining (as you refer to as “linear mesh”), or point to multipoint. Having one piece of equipment makes not only for a simplified install and configuration, but also great for sparing. Both are efficient and cost saving.

    Nice Job!

    Comment by Joe Wargo — April 26, 2010 @ 12:32 pm | Reply

    • Correct, the head nodes, as well as the ‘nesting’ (repeater) nodes are dual radio nodes, as indicated by ’6202′ notations. 6202 stands for dual-radio outdoor Firetide HotPort 6000 series. The edge nodes are single-radio (6201 is single-radio outdoor Firetide HotPort). Also note that the repeater nodes are deployed with two antennas – one (typically panel) back to the ‘upstream node’, and and the other (sector – for wider coverage) to the multiple ‘downstream’ nodes. So yes, this is similar to PtP and PtMP, but the nesting aspect and the combination of topologies are unique to mesh gear, as Joe noted.

      Comment by kseniacoffman — April 26, 2010 @ 2:57 pm | Reply

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