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Designing and Installing Wireless Ethernet Systems
Wireless Ethernet Radios The most common questions… Do I need backhaul, multiple access, cellular or mesh? What type of antennas to use? How far will the link go? How does the system handle interference? How does the data rate change with distance? How is security handled? How to setup an installation? How to install multiple systems in close proximity? What about power supply? What to do about lightning?
What is the difference between backhaul, multiple access and mesh? Backhaul solutions are optimized for fixed point to point connections. Longest range and highest success rates. Fixed Multiple Access solutions are optimized to support several simultaneous device as fixed locations. Great for surveillance applications. Cellular systems are versatile but require monthly fees. They are relatively inexpensive to buy and install. Specialized radios with high quality antennae at elevated locations have best success. Busy populated venues often have throughput issues. Mesh systems require high radio node density. They are relatively expensive to buy and install. Smaller node counts have better success and higher throughputs.
Location #2 17 m ile s “Backhaul” systems with directional antennae Location #1 Location #3 Main Location Point to Point radios – each subscriber gets a dedicated radio link for maximum throughput.
“Directional antennae” “Sector antennae” 17 m ile s Location #2 Location #4 Location #3 Location #1 Main Location Multipoint radios – data rate is shared between subscriber radios in sector
Location #2 4 m ile s “Backhaul” systems with directional antennae Location #1 Location #3 Omni Antenna Multipoint radios – data rate is shared between subscriber radios Main Location
1, 0 00 ft 1000 ft 10 00 ft “Portable or Mesh” systems with Omni antennae 1, 0 00 ft 0 1, 00 Omni Antenna Multipoint/mesh radios – Data is shared and repeated between subscriber radios Main Location ft
Mesh and Spoke
How far will the link go?
How far will the radio go? Radio Link Budget – Free Space Loss = System operating margin >18 d. B is safe
Link Budgets At 900 Mhz with 15 d. Bi 21 d. B 15 d. B 0 d. B 97 d. B 15 d. B 0 d. B _____ Link Budget = At 5800 Mhz + transmitter power + transmitter antenna gain – transmitter cable losses + receiver sensitivity + receiver antenna gain – receiver cable losses __________ Link Budget = 148 d. B 123 d. B with 23 d. Bi 21 d. B 23 d. Bi 1 d. B 97 d. B 23 d. Bi 1 d. B _____ + transmitter power + transmitter antenna gain – transmitter cable losses + receiver sensitivity + receiver antenna gain – receiver cable losses __________ with 2. 5 d. Bi 21 d. B 2. 5 d. Bi 0 d. B 97 d. B 2. 5 d. Bi 0 d. B _____ with 5 d. Bi 21 d. B 5 d. Bi 0 d. B 97 d. B 5 d. Bi 0 d. B _____ 162 d. B 128 d. B
Free Space loss Free space loss = 20 log(Freq in MHz) + 20 log(distance in miles) +36. 6 Distance 900 MHz: 5800 MHz: 0. 1 mile has 76 d. B of loss 92 d. B of loss 1 mile has 96 d. B of loss 112 d. B of loss 10 miles has 116 d. B of loss 132 d. B of loss 50 miles has 130 d. B of loss 146 d. B of loss
Line of Sight Examples: Will a 5. 8 Ghz Ava. LAN link work at 40 miles using 23 d. Bi panels on both ends? Yes: Link budget (162 d. B) – Free space loss (144 d. B) = System operating margin (18 d. B) Will a 900 Mhz Ava. LAN link work at 50 miles using a 15 d. Bi yagis on both ends? Yes: Link budget (148 d. B) – Free space loss (130 d. B) = System operating margin (18 d. B) Will a 5. 8 Ghz Ava. LAN link work at 5 miles using a 5 d. Bi omni and a 23 d. Bi panel? Yes: Link budget (145 d. B) – Free space loss (126 d. B) = System operating margin (19 d. B) Will a 5. 8 Ghz Ava. LAN link work at 3/4 mile using 5 d. Bi omnis on both ends? Yes: Link budget (128 d. B) – Free space loss (109 d. B) = System operating margin (18 d. B)
Diffractive Non-line-of-sight Angle of Attack 900 Mhz 2. 4 GHz 5. 8 GHz 500 ft 10 Degrees 20 ft 2 Miles Angle of attack 1° 5° 10° Distance 10 Miles 5 Miles 1 Miles
Penetrating Non Line of Sight Up to 1 500 ft
Indoor Non Line of Sight
How does the data rate change with distance? An AW 900 systems should only be affected by the added 3% speed of travel delay. An AW 58100 systems at a 50 mile link will have a 80% data reduction due to slower coding gain required to achieve distance.
How is security handled? AES keyed encryption – FIPS 197/140 -2 Encryption at the application layer is becoming a preferred technique for securing sensitive communications.
Robust against interference? How does the system handle interference? In band out of band? How easy is the system to intentionally jam? Is the system able to autonomously coexist or is a truck roll required to perform a site survey and change channel ?
How to setup multiple systems in close proximity? Use high gain antennae to isolate and direct energy… For Pt to Pt, Keep the units paired together… Setup one link at a time with the others off… Adjust antennae to create sufficient isolation between links use angular, polarization, spectral and spatial separation…
Isolation techniques Delta Horizontal Polarization Angular Vertical Polarization
Power supply options? Ava. LAN offers two power supply accessories. Indoor AW 12 V - cigarette lighter powered mobile applications. Outdoor AW 24 V - 24 VAC power common in security markets The radios are midspan POE powered from 12 VDC to 48 VDC. For solar applications it is possible to power the AW 900 radio in continuous transmit with 12 VDC at 120 m. A = 1. 5 Watts of power draw. For solar applications it is possible to power the AW 58100 radio in continuous transmit with 12 VDC at 500 m. A = 6 Watts of power draw.
How to provide lightning protection? Ava. LAN’s antennae are DC grounded. However, the use of inline lightning suppressor is always a good idea. Mount the antenna at least 3 ft from the top of a grounded pole