Mesh Network applications often require a string-of-pearls formation where the end-to-end path is non line-of-site (NLOS). Additionally, there may be points along the path where
sensor data needs to be collected. One typical such application is perimeter surveillance using remote video cameras mounted at regular intervals along the perimeter being
Figure 1: Camera input may be wired in directly into
Meshdynamics Ethernet Port IXP1 (right)
A perimeter-surveillance deployment does not require the use of 2.4GHz AP radios for client access. The MD4250-AAxx is therefore the most suitable mesh node. IP cameras may be wired into the right-hand Ethernet port on the node, and directional antennas can be used on the uplink and downlink radios
for more range between nodes.
If a 2.4GHz wireless
IP camera is used in the deployment, the
will be needed in the line of mesh nodes to provide the AP to which the camera can associate.
Otherwise the MD4250 is sufficient for wired camera input.
Dual Backhaul Root node converges data traffic from
Figure 2 depicts two string-of-pearls mesh chains “snakes”
around the perimeter of an airport. The large blue box is
node with two backhaul downlinks to cover both directions
- the two string of pearls chains. Traffic from both
chains converges via the Ethernet port connected to the root
node. A MD4454 can support up to
4 such forks.
radio, basic backhaul configuration comes in two flavors. MD4250-AAxx
uses radios configured to operate in the 5GHz spectrum. MD4220-IIxx
uses radios configured to operate in the 2.4 GHz spectrum.
When deciding whether to use 2.4GHz based products (4220) vs
the 5.8GHz (4250) product, RF pollution must be considered.
Wi-Fi 802.11b/g clients are 2.4GHz and will interfere with a
2.4GHz node-to-node (backhaul) link.
In addition, 802.11b clients - if attached to the 2.4GHz
backhaul downlink will slow the performance of of the
4220 mesh nodes thus should be limited in servicing few
child nodes. On the positive side, 2.4 GHZ has about twice
the range at 5GHz, so 4220 are preferable where range
supersedes backhaul capacity. 4220 are also
used when the nodes are edge based - that is no child nodes connected to
1. Perimeter Security For Department of Homeland Security
(DHS) Web Page
2. Tutorial on choosing Frame Rate etc for video camera,
based on backhaul capacity
3. Calculations of range based on radio settings and node
Mesh Network Layout Design
Point Range and
Antenna Alignment. Range Calculations Related.