Kyle Mason

Mesh networks requirements have evolved from their military origins as they have moved from battlefield to the service provider, to the residential networking environments. Today, to cover large areas with a single wired Internet link, more cost effective and efficient means of bandwidth distribution are needed. Growing demands in video and voice data require a higher transfer rate with low latency and interference. This requires more node or hops

Mesh Architectures There are three generation of mesh architectures: Generation 1 / Ad Hoc Generation 2 / 1-Radio Meshed Backhaul Generation 3 / 3-Radio Structured Meshed

First Generation 1-Radio Ad Hoc Mesh This network used one radio channel to both send and to provide mesh backhaul. Service and backhaul compete for the same bandwidth

Second Generation Duel-Radio with Single Radio Ad-Hoc meshed Backhaul Each node contains two radios One radio is for providing service The second radio provides backhaul on a second radio band Only downside is packets traveling toward the Internet share bandwidth at each hop along the backhaul path with other nodes.

Third Generation 3-Radio Structured Mesh Each node contains two radios One radio is for providing service The second radio provides backhaul The difference between second and third generation is that third generations backhaul signals are managed my each node and sent on a separate channel

Bandwidth Degradation on Single Channel Backhauls Mesh networks use a store-and-forward way of relaying data. One node receives data, has to completely store the data in order to forward it on to the next.

Bandwidth Degradation on Single Channel Backhauls (cont) Each time a node has to wait, it loses ½ of its bandwidth. So, after 4 waits, the bandwidth go to ½ X ½ X ½ X ½ = 1 / 16 This is a 1/(2 N ) relationship

Bandwidth Degradation on Single Channel Backhauls (cont) Third Generation eliminates the bandwidth degradation by using duel channel backhaul This improvement over first and second generations allows the support of video and voice transition.

Latency/Jitter Degradation Latency is directly related to available bandwidth. Poor bandwidth results in higher latency and more jitter over multiple hops.

Latency/Jitter Degradation (cont) First generation single channel backhaul networks provide reliable video/voice over only one or two hops. Third generation mesh products don’t suffer from bandwidth degradation. The use of multiple backhaul radios what allows this. Third generation has a 1 millisecond per hop latency even under heavy traffic.

Frequency Agility through Distributed Intelligence How to you provide two-radio backhauls over a wireless mesh network? One of the first approaches was to use hardware radio switching and sectored directional antennas. Although this did work, the limitations was too much. Another approach is to distribute dynamic radio intelligence in each node. Each node would then monitor the air for both system on the network as well as harmful interference. Then based of the information, it would then choose the best channel to use.

Frequency Agility through Distributed Intelligence (cont) How to you provide two-radio backhauls over a wireless mesh network? Another approach is to distribute dynamic radio intelligence in each node. Each node would then monitor the air for both system on the network as well as harmful interference. Then based of the information, it would then choose the best channel to use. This method usually forms a tree like structure. As the tree branches out, the nodes get further away from each other allowing reuse of channels to improve network performance.

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