Wireless Network Deployment Tips and Tricks 2012

Transcription

1 Wireless Network Deployment Tips and Tricks 2012 Written by Danial Szgatti, Business Development and Marketing Manager at ENCOM Wireless Data Solutions Introduction: Key Points: Planning In the past 12 years, there have been a lot of advancements in communication technology that have enabled connectivity 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 effective and reliable wireless networks. As with most technologies, it is crucial to design and install the system correctly for maximum performance and reliability. The following article describes tips and tricks that will ensure that Wireless is Simple! Figure 1 Thorough design and planning are crucial Antenna location must be optimized for clear line of sight Height is critical, avoid obstructions Take time to align antennas, every dbm counts Weather proof all connections Tighten all fasteners to correct torque settings Document As Built network status 1. Google Earth - mapping, layout, distance measurement, elevation profile a. Enables documentation of all information on one easy to read source b. Flexible c. Up to date d. Consider using a GIS software like MS MapPoint or ArcGIS 2. RF Planning Tool - An RF planning tool is essential: Micropath, Pathloss, a. Determine if terrain obstructions are present b. Analyze predicted signal levels, bandwidth, uptime etc c. If a sector antennas will be used design the frequency reutilization to get most efficient design possible: Example of Terrain Profile: (Figure 1) Figure 2 Example of an Area Study predicting the signal strength based on topography: (Figure 2) Page 50 Cont. on page 51 IMSA Journal

2 Wireless Network Deployment Tips and Tricks Continued from page 50 Type of Device Traffic Controller/UPS/MMU MJPEG Video MPEG-2 Compressed Video MPEG-4 Compressed Video (Standard Resolution): H.264/MPEG-4 AVCHD Video (Hi Def 1080p): Bandwith Required <10Kbps Mbps 3-4 Mbps 1-2 Mbps 1-2 Mbps Figure 3: Example of RF Channel reutilization on non adjacent sectors. 3. Perform Visual Site Survey to evaluate: a. Obstructions b. Site layout c. Power/data/infrastructure assessment d. Take pictures for future reference e. Do a drive by survey based on the map from Google 4. Perform Wireless Site Survey: Obtain Wireless Field Strength Measurements: Real World Conditions a. 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 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: 6. Design with future uses in mind: a. Additional equipment b. Additional sites within the network c. Mobile Workforce applications d. New standards: a n e. Define the security requirement and the SSID schema f. Define where do you need dual radios and single radio units g. 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 / limitations) a. Frequencies: 900Mhz, 2.4 GHz, 5.8 GHz, 4.9 GHz b a/b/g c N: MIMO: newest standard with up to 300 Mbps bandwidth: The n technology standard offers a variety of physical layer diversity mechanisms for achieving higher throughput and improved packet reception capability. Each n 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 processing. When discussing n 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 Radio e. 2.4 GHz Wi-Fi access point f. POE: 802.3AF: 48 VDC Standard: up to 100M/ 300 ft CAT5 Cable i. POEs that do not meet this standard may not have the reach/ reliability over long distances. g. Network Monitoring Software: Whatsup Gold, HP OpenView, SNMP h. Radio Monitoring Software: STRATOS 5. Understand the Application: a. Evaluate Present and future equipment site equipment 8. Network Topology: requirements a. Pt to PT: point to point b. What type of Data is required: Ethernet / Serial Contact b. Pt to MPT: point to multipoint / Closure c. MESH c. Know your bandwidth requirements: Continued on page 52 January/February 2013 Page 51

3 Wireless Network Deployment Tips and Tricks Continued from page 51 Wireless Architectures Point to Point Solutions Repeater Solutions Antennas: Antenna Type Parabolic Dish Panel Sector Omni Gain 30 db 20 db db 10 db Beam Width 4 degree degree degrees 360 degree i. Single polarity: Vertical OR Horizontal ii. Dual Polarity : Both horizontal and vertical operate simultaneously 1. Required for full bandwidth n systems 2. Dual Spatial streams = twice as much bandwidth. Directional antennae used on the MASTER and Remote location provide maximum throughput Point to Multi-Point Solutions Down the line remotes experiencing line of sight issues can be chained together using native repeater functionality; Mesh Solutions 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 wireless 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 network design b. Plan most efficient methodology to visit each site and capture field strength measurements. Example of Preliminary wireless plan as prepared by ENCOM Wireless: When Sites are in a line, a directional antenna can be used at the MASTER location; Bandwidth is maintained 5. Perform detailed site survey using bucket truck and temporary wireless equipment Bucket Truck a. Data to be captured: Location Information Location of Test Height of Test (can be numerous at each site) Visual Description of radio path (clear, some trees, obstructed) Radio equipment information: - Frequency of operation - Antenna type - Output power Page 52 Mesh topologies represent the best way to ensure maximum performance reliability and redundancy Temporary Wireless Equipment Wireless Measurements Wireless signal level measurements RSSI Receive Signal Strength Indicator CCQ: Conection Quality TX/RX Signaling Rate Bandwidth Available Interference-Spectrum Scan Ping Test Continued on page 53 IMSA Journal

4 Wireless Network Deployment Tips and Tricks Continued from page How to perform a site survey? 1. Temporarily install master transmitter at proposed location 2. 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 location 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. c. Height is key d. 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 intersection, mount each one independently as to maximize signal levels. 8. Installation Tips: 1. Mount antennas as high as possible 2. Ensure all strain reliefs are in place and the cable has a drip loop 3. Weatherproof all cable connections a. Especially important for RF coaxial connectors 4. Secure all cables to the infrastructure with zip ties 5. Align antenna a. Spend 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 considered 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 software 3. 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. 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 location a. Focus on: no obstructions in radio path b. For traffic applications, mount radio overtop of Continued on page 54 the roadway January/February 2013 Page 53

5 Wireless Network Deployment Tips and Tricks Continued from page 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 alignment adjustment: How to interpret the results: Green = Good Yellow = Acceptable Red = Poor quality Please note the signal level quality differences between a and n systems. In order to obtain optimal results with n, 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 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. 2. Monitor the link Status in Real-Time a. RSSI: Signal Level b. CCQ: Connection Quality Azimuth 1. Loosen the azimuth adjuster on the antenna mount horizontal angle) and adjust azimuth position for maximum RSSI/RSL. Page Document As Built status of the network Continued on page 55 IMSA Journal

6 Wireless Network Deployment Tips and Tricks Continued from page 54 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 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! What to do: Note: The radio is completely obstructed by the trees. Note: Great mounting location, perfect line of site, no obstructions. 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 Fiber Optic IMSA Certification Training for Traffic Systems The Light Brigade s training programs, designed for the Traffi c Systems professional, offer two levels of instruction. These courses provide a practical understanding of how fi ber optic technology is integrated into modern traffi c systems and cover essential learning objectives for the IMSA certifi cation testing. Courses updated for Fiber Optics for Traffic Systems Level I: Two days of classroom training on basic theory of fi ber optics and advanced topics for transmissions systems. It is designed for Operations and Maintenance Supervisors, Design Engineers, and ITS Managers. A prerequisite for Level II. Fiber Optics for Traffic Systems Level II: Two days of in depth hands-on training to master the skills needed when working with fi ber optic systems in the fi eld. If our regularly scheduled programs do not fi t your needs, we also offer a custom training program for six or more attendees at the time and location of your choice. Contact sales@lightbrigade.com for more details. For a complete description of the course offerings and class schedules, visit our website at (800) sales@lightbrigade.com January/February 2013 Page 55