Download First, Second, and Third Generation Mesh Architectures

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:
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Generation 1 / Ad Hoc
Generation 2 / 1-Radio Meshed Backhaul
Generation 3 / 3-Radio Structured Meshed
First Generation
 1-Radio Ad Hoc Mesh
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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
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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
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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/(2N) 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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