Wireless Mesh Networks for Video Surveillance: Why and How
Available wireless topologies include point-to-point wireless systems, which provide connections between two fixed locations. Low-capacity bridges are typically used for one or two outlying cameras; high-capacity links are ideal for backhaul of other wireless networks.
There are also point-to-multipoint wireless systems, which deliver network connections to multiple remote locations from a central location. These systems may offer a cost effective solution if tall assets (towers or buildings) are available; however, the central “base unit” creates a single point of failure â€” if this unit becomes inoperative, the whole network goes down.
There also are multipoint-to-multipoint (wireless mesh) systems, which deliver multi-hop connectivity to extend the reach of the system. Redundant links eliminate single points of failure associated with conventional wireless networks, while multiple paths overcome line-of-sight issues.
The choice of the technology will depend on your particular deployment; you should consider pros and cons ahead of time. Wireless mesh is often the most attractive choice for professional video surveillance, because it provides the required throughput, redundancy and multiple paths to ensure reliability of video transmission.
The flexibility of mesh allows it to be deployed in any of the above scenarios â€” point-to-point for backhaul, point-to-multipoint, or “true” mesh for complete redundancy. Some deployments start as point-to-multipoint, later to be reconfigured into a mesh topology, when security needs call for ubiquitous coverage.
What should a solution provider look for in a wireless solution?
All wireless technologies are not created equal and extensive due diligence should be part of your technology selection process. Things to look for:
• Video Performance: Video surveillance requires an extensive amount of bandwidth, especially the new megapixel and high-definition cameras. Today’s wireless mesh networks based on MIMO (multiple input multiple output) 802.11n technology deliver fiber-equivalent throughput: up to 300 Mbps outdoors with .9 ms latency.
• Security and Privacy of Video Streams: The most secure systems offer end-to-end encryption supporting AES, WPA2 and WEP. In addition to encryption, encapsulation schemes can also be used to add a layer of security, because only the mesh nodes can see the encapsulated packets.
• Multicasting: Multicasting enables video feeds to be sent to multiple destinations for simultaneous viewing and recording. Multicasting is essential for monitoring by multiple decision makers, but can severely burden a wireless network. Encapsulation techniques, in addition to increasing security, enable multicasting of video streams across wireless networks while minimally impacting bandwidth.
• Extended reach: Mesh’s multi-hop capabilities allow you to extend the network into areas where point-to-multipoint networks cannot reach, due to topology limitations.
• Flexibility and Expandability: The technology used should make it easy to gradually grow the network â€” as funds become available, new departments come on board, or there is a need to cover new areas. Wireless mesh has the advantage of allowing capacity growth without impacting overall throughput on the network, or requiring a redesign of the network.
• Ease of Setup: This is especially critical for temporary installations, where the installer may only have a few hours to get the system in place. Even in fixed installs, the cameras often need to be repositioned as conditions change. Unlike with a point-to-multipoint system, any mesh node can act as a “head end” â€” allowing multiple command centers to be set up, at any point on the network.
• Mobility: When you need the ability to maintain real-time connections between fixed and mobile nodes moving at high speeds â€” without dropping packets and introducing latency or jitter â€” only mesh will fit the bill. Wi-Fi access “client mobility” (such as between access points and laptops) is enough to support non-critical low-bandwidth data, but is not sufficient to deliver real-time video streaming. Similarly, you cannot truly implement mobility with point-to-multipoint equipment, because of the central ‘command-and-control’ architecture, which does not allow for roaming. Mesh, with its distributed architecture and built-in intelligence, can support mobility within the mesh and even roaming across multiple meshes.
Contributed by Ksenia Coffman (firstname.lastname@example.org), marketing manager, Firetide, Los Gatos, Calif
To learn more about all the wireless solutions available from Firetide, including wireless mesh, and to see the products in person, please visit booth #24083 at ISC West or go to www.firetide.com.