wireless network deployment tips and tricks 2012 rsl and/or rssi voltage in the commissioning log....

Page IMSA Journal50

Introduction:

In the past 12 years, there have been a lot of advancements in communication technology that have enabled connec-tivity and increased bandwidth within our systems. The most cost effective of these technologies are dedicated wireless networks. Companies like ENCOM Wireless Data Solutions are pioneers in the traffic industry and have continued to provide cost effec-tive and reliable wireless networks. As with most technologies, it is crucial to design and install the system correctly for maximum performance and reli-ability. The following article describes tips and tricks that will ensure that “Wireless is Simple!”

Written by Danial Szgatti, Business Development and Marketing Manager at ENCOM Wireless Data SolutionsWireless Network Deployment Tips and Tricks 2012

Key Points:

• Thorough design and planning are crucial

• Antenna location must be optimized for clear line of sight

• Height is critical, avoid obstruc-tions

• Take time to align antennas, every dBm counts

• Weather proof all connections• Tighten all fasteners to correct

torque settings• Document ‘As Built’ network sta-

tus

www.encomwireless.com Email: [email protected]

1. Google Earth - mapping, layout, distance measurement, elevation profile a. Enables documentation of all

information on one easy to read source

b. Flexiblec. Up to dated. Consider using a GIS software

like MS MapPoint or ArcGIS

2. RF Planning Tool - An RF plan-ning tool is essential: Micropath, Pathloss,a. Determine if terrain obstruc-

tions are presentb. Analyze predicted signal lev-

els, bandwidth, uptime etcc. If a sector antennas will be

used design the frequency re-utilization to get most efficient design possible:

Example of Terrain Profile: (Figure 1)

Example of an ‘Area Study’ predicting the signal strength based on topography: (Figure 2)

Figure 2

Figure 1

Cont. on page 51

January/February 2013 Page 51

Type of Device Bandwith RequiredTraffic Controller/UPS/MMU <10KbpsMJPEG Video 10-15 MbpsMPEG-2 Compressed Video 3-4 MbpsMPEG-4 Compressed Video 1-2 Mbps(Standard Resolution):H.264/MPEG-4 AVCHD Video 1-2 Mbps(Hi Def 1080p):

6. Design with future uses in mind:a. Additional equipmentb. Additional sites within the networkc. Mobile Workforce applicationsd. New standards: 802.11 a 802.11 ne. Define the security requirement and the SSID

schemaf. Define where do you need dual radios and single

radio unitsg. Based in the wireless discovery plan where 2.4Ghz

or 5.8 GHz can be used, consider the pros and cons of each band

7. Understand the technology: (advantages / limita-tions)a. Frequencies: 900Mhz, 2.4 GHz, 5.8 GHz, 4.9

GHzb. 802.11 a/b/gc. 802.11N: MIMO: newest 802.11 standard with up

to 300 Mbps bandwidth: The 802.11n technology standard offers a variety

of physical layer diversity mechanisms for achiev-ing higher throughput and improved packet reception capability. Each 802.11n radio can have multiple transmit antennas and paths. Multiple spatial data streams can be transmitted at the same time, on the same channel, but by different antennas. The data streams can be combined from multiple receivers using advanced signal process-ing. When discussing 802.11n or MIMO networks, three numbers are typically referenced – the first is the number of transmit antennas, the second is the number of receive antennas and the third is the number of spatial streams. For example, a 3x3:2 system has three transmit signals, three receive signals and two spatial streams.

d. Single Radio vs./ Dual Radioe. HotSpot: @ 2.4 GHz Wi-Fi access pointf. POE: 802.3AF: 48 VDC Standard: up to 100M/

300 ft CAT5 Cablei. POEs that do not meet this standard may

not have the reach/ reliability over long dis-tances.

g. Network Monitoring Software: Whatsup Gold, HP OpenView, SNMP

h. Radio Monitoring Software: STRATOS

8. Network Topology:a. Pt to PT: point to pointb. Pt to MPT: point to multipointc. MESH

Continued on page 52

3. Perform Visual Site Survey to evaluate:a. Obstructionsb. Site layoutc. Power/data/infrastructure assessmentd. Take pictures for future referencee. Do a drive by survey based on the map from Google

4. Perform Wireless Site Survey: Obtain Wireless Field Strength Measurements: Real World Conditionsa. Signal Level Assessment (dBm)b. Noise Levels – Spectrum Scan (SNR)c. Available bandwidth measurements (MBPS)d. Ping Test (ms)e. Run a discovery wireless network using a laptop

equipped with ABGN radio and software analyzer (ex. insider http://www.metageek.net/support/down-loads) save the data and use later to setup the radios using the right channels

ENCOM STRATOS software provides all of the information required to complete the site survey:

5. Understand the Application: a. Evaluate Present and future equipment site equipment

requirementsb. What type of Data is required: Ethernet / Serial Contact

/ Closurec. Know your bandwidth requirements:

Wireless Network Deployment Tips and Tricks 2012 . . . Continued from page 50

Figure 3: Example of RF Channel reutilization on non adjacent sectors.

Page IMSA Journal52

Antennas:

Antenna Type Gain Beam WidthParabolic Dish 30 dB 4 degreePanel 20 dB 10-12 degreeSector 12-17 dB 45-120 degreesOmni 10 dB 360 degree

i. Single polarity: Vertical OR Horizontal

ii. Dual Polarity : Both horizontal and vertical operate simulta-neously

1. Required for full band-width 802.11n systems

2. Dual Spatial streams = twice as much band-width.

Wireless network design 101

Goal: Achieve the clearest radio path between locations.

1. Evaluate Terrain. Use high spots for master/ repeater radios to expand coverage.

a. Look for cell phone towers/ radio towers - they are on the high points of land

2. Evaluate infrastructure: do you have high mast lighting, radio towers, or luminaires that could be leveraged as part of the wire-less network

3. Plan field visits for visual site survey based on above analysis

4. Create preliminary wireless plan:

a. Compile all information and build an initial net-work design

b. Plan most efficient meth-odology to visit each site and capture field strength measurements.

Example of Preliminary wireless plan as prepared by ENCOM Wireless:


Wireless Architectures

Point to Multi-Point Solutions Mesh Solutions

Directional antennae used on the MASTER and Remote location provide maximum throughput

Point to Point Solutions Repeater Solutions

Down the line remotes experiencing line of sight issues can be chained together using native repeater functionality;

When Sites are in a line, a directional antenna can be used at the MASTER location; Bandwidth is maintained

Mesh topologies represent the best way to ensure maximum performance reliability and redundancy

5. Perform detailed site survey using bucket truck and temporary wireless equipment

a. Data to be captured:

Location Information Wireless Measurements• LocationofTest Wirelesssignallevelmeasurements• HeightofTest(canbenumerous RSSIReceiveSignalStrength at each site) Indicator• VisualDescriptionofradiopath CCQ:ConectionQuality (clear, some trees, obstructed) TX/RX Signaling Rate• Radioequipmentinformation: BandwidthAvailable - Frequency of operation Interference-Spectrum Scan - Antenna type Ping Test - Output power

Temporary Wireless EquipmentBucket Truck




6. How to perform a site survey?1. Temporarily install master transmitter at proposed

location2. While at the master site, test remote unit to ensure

configuration is correct prior to moving to the next test site.

3. Travel to remote sites with a bucket truck and test link quality

a. Move to different ‘micro sites’ within that loca-tion to choose optimal mounting location

Examples of ‘Micro sites’:Note: In the above example the red line indicates a weak signal; the green line indicates a strong signal. Although the sites are only 40 feet apart, the obstructions are very different hence the different in signal quality.

4. Align antenna as per instructions below to ensure an accurate test. It is safe to assume that the signal will improve by 3-5 dBm upon permanent installation.

5. Record all information on a spreadsheet or Google earth for future reference

6. Visit all sites proposed and perform the same tests.

7. Plan the network deployment:1. Pinpoint the location of the antenna/radio for every

locationa. Focus on: no obstructions in radio pathb. For traffic applications, mount radio overtop of

the roadway

c. Height is keyd. On straight roads, choose different sides of

the street for the master and remote radios to minimize obstructions

e. If numerous radios are present at an intersec-tion, mount each one independently as to maximize signal levels.

8. Installation Tips:1. Mount antennas as high as possible2. Ensure all strain reliefs are in place and the cable has

a drip loop3. Weatherproof all cable connections a. Especially important for RF coaxial con-

nectors4. Secure all cables to the infrastructure with zip ties5. Align antenna a. Spend 10-15 minutes at each site precision

aligning the antenna.6. Secure all mounting hardware, use lock tight thread

locker in high vibration locations

9. How to align antennas?1. When aligning the antennas, each link must be con-

sidered independently. Visit both ends of the link and align the antennas for maximum signal level. For multipoint systems, it is recommended that all remote locations are aligned prior to the master. This will enable you to ensure optimal master alignment to all remotes.

2. Rough alignment a. Visual b. Based on Compass Bearing i. Azimuth = generated by the radio path

analysis software3. Precision Alignment:

a. Once a link has been formed using rough alignment, precision alignment using ENCOM STRATOS software will ensure optimal wireless link performance. It is important to understand how to interpret the results. Below is a quick reference for 5.8 GHz broadband equipment. In the field, the color coding of the bar graphs eliminates guess work. Green means go, yellow means caution, and red means stop.


Page IMSA Journal54


How to interpret the results:Green = GoodYellow = AcceptableRed = Poor quality

Please note the signal level quality differences between 802.11a and 802.11n systems. In order to obtain optimal re-sults with 802.11n, the signal levels must be very strong.

Adaptive Modulation:Keep in mind that due to the adaptive modulation feature, minor changes in the RSSI can have a profound impact on the wireless data signaling rate. When doing the precision alignment, take your time and achieve the maximum possible signal level. Not only will this maximize the total available bandwidth but it will also increase the long term reliability of the network.

1. Beginning at one end of the system, connect to the radio using STRATOS

2. Monitor the link Status in Real-Time a. RSSI: Signal Level b. CCQ: Connection Quality

Azimuth1. Loosen the azimuth adjuster on the antenna mount hori-

zontal angle) and adjust azimuth position for maximum RSSI/RSL.

2. Tighten the azimuth securing mechanism, ensuring the indication does not drop as it is tightened.

3. Loosen the elevation adjuster vertical angle) and adjust for maximum RSSI/RSL.

4. Tighten the elevation securing mechanism; ensuring indication does not drop as it is tightened. The unit is now aligned and ready to carry operational traffic.

5. Record RSL and/or RSSI voltage in the commissioning log.

While monitoring the RSSI, move the antenna in 1 cm or ½ inch increments left then right.

Example of signal level changes with 1 cm / ½ Inch align-ment adjustment:

Elevation (Vertical Alignment)1. Vertical Alignment (Up <-> Down): move the antenna

slowly up then down while monitoring the RSSI. During this process the signal level may increase or decrease. It is important to characterize the general direction and then hone in on the exact target (Maximum signal level).

2. When the optimal signal is achieved, make a mark on the antenna mount for future reference.

While monitoring the RSSI, move the antenna in 1 cm or ½ inch increments up and down.

Shown left: Example of signal level changes with 1 cm / ½ inch alignment adjustment:

Once the maximum signal level is reached at a particular site, align the alignment marks and tighten all of the fasteners to the appropriate torque setting.

10. Document ‘As Built’ status of the networkContinued on page 55


What not to do:

Note: The mount for the radio was not tightened enough and it rotated towards the moon. Good line of site (LOL); but no one out there!

Note: The radio is completely ob-structed by the trees.

ENCOM Wireless is a leader in designing and deploying wireless networks for ITS and Traffic management systems. ENCOM provides outdoor rated wireless networks designed to provide error free communications. For more information on ENCOM, please visit our website at www.encomwireless.

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Key Points:• Thorough design and planning are crucial• Antenna location must be optimized for clear line of

sight• Height is critical• Take time to align antennas, every dBm counts• Weather proof all connections• Tighten all fasteners to correct torque settings

What to do:

Note: Great mounting location, perfect line of site, no ob-structions.

wireless network deployment tips and tricks 2012 rsl and/or rssi voltage in the commissioning log....

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