- Calculations necessary for outdoor bridging surveys are numerous, including the Fresnel zone, earth bulge, free space path loss, link budget, and fade margin.
- Outdoor site surveys for the purpose of providing general outdoor wireless access for users are becoming more commonplace.
- As the popularity of wireless mesh networking continues to grow, outdoor wireless access has become more commonplace.
- Outdoor site survey kits using outdoor mesh APs will be needed.
- Weather conditions, such as lightning, snow and ice, heat, and wind, must also be contemplated.
- Most important is the apparatus that the antennas will be mounted to.
- Unless the hardware is designed for outdoor use, the outdoor equipment must ultimately be protected from the weather elements by using NEMA-rated enclosure units (NEMA stands for National Electrical Manufacturers Association)
- NEMA weatherproof enclosures are available with a wide range of options, including heating, cooling, and PoE interfaces.
- The key concern during government wireless site surveys is security.
- When security expectations are addressed during the interview process, careful consideration should be given to all aspects of planned security.
- Many U.S. government agencies, including the military, require that all wireless solutions be FIPS 140-2 compliant.
- Other government agencies may require that the wireless network be completely shielded or shut off during certain times of the day.
- Be sure to check export restrictions before traveling to other countries with certain equipment.
- The United States forbids the export of AES encryption technology to some countries.
- Other countries have their own regulations and customs requirements.
- Obtaining the proper security credentials will most likely be a requirement before conducting the government survey.
- An identification badge or pass often is required.
- In some government facilities, an escort is needed in certain sensitive areas.
- Obtaining the proper security credentials in an education environment usually is necessary.
- Properly securing access points in lockable enclosure units is also necessary to prevent theft or tampering.
- Because of the high concentration of students, user density should be accounted for during capacity and coverage planning.
- K–12 schools across the United States are implementing 1:1 iPad deployments, where every student in every classroom has access to an iPad tablet. Because of these 1:1 programs, it is not uncommon to deploy an access point in every classroom to meet the device density needs.
- In campus environments, wireless access is required in most buildings, and very often bridging solutions are needed between buildings across the campus.
- Some older educational facilities were constructed in such a manner as to serve as disaster shelters. That means that propagation in these areas is limited.
- Most school buildings use dense wall materials such as cinderblock or brick to
attenuate the sound between classrooms. These materials also heavily attenuate RF signals.
- One of the biggest concerns in a healthcare environment is sources of interference from the biomedical equipment that exists on site.
- Many biomedical devices operate in the ISM bands. For example, cauterizing devices in operating rooms have been known to cause problems with wireless networks.
- There is also a concern with 802.11 radios possibly interfering with biomedical equipment.
- A meeting will be necessary with the biomedical department that maintains and services all biomedical equipment.
- Some hospitals have a person responsible for tracking and monitoring all RF devices in the facility.
- A thorough spectrum analysis survey using a spectrum analyzer is extremely important.
- It is recommend that you conduct several sweeps of these areas and compare them to ensure the greatest probability of capturing all the possible interferers.
- Because of the many potential sources of interference in the 2.4 GHz ISM band, it is likely that 5 GHz hardware will be deployed in many areas.
- Often, the dense environments require 5 GHz simply because you will need more channel options to prevent co-channel interference.
- Hospitals are usually large in scale, and a site survey may take many weeks; a
predictive site survey can save a lot of time.
- Long hallways, multiple floors, fire safety doors, reflective materials, concrete construction, lead-lined X-ray rooms, and wire mesh safety glass are some of the physical conditions that you will encounter during the survey.
- The applications used in the medical environment should all be considered during the interview and the survey.
- Numerous healthcare applications now exist for handheld iOS and Android devices.
- Tablets and smartphones are being used by doctors and nurses to access
these mobile applications.
- Mobile devices are also used to transfer large files, such as X-ray graphics.
- Medical carts use radios to transfer patient data back to the nursing stations.
- VoWiFi phone deployments are commonplace in hospitals because of the communication mobility that they provide to nurses.
- Wi-Fi real-time location systems (RTLSs) using active 802.11 RFID tags are commonplace in hospitals for asset management tracking.
- Because of the presence of medical patients, proper security credentials and/or an escort will often be necessary.
- Many applications are connection oriented, and drops in connectivity can be detrimental to the operation of these applications.
- Hotspots continue to grow in popularity, and many businesses are looking to provide wireless Internet access for their customers.
- Many hotspots are small, and care should be taken to limit the RF coverage area by using a single access point at a lower power setting.
- However, some large facilities, such as airports and convention centers, have begun offering wireless access, and obviously multiple access points and wider coverage will be needed.
- Security solutions at hotspots are usually limited to a captive portal solution for user authentication against a customer database.
- A retail environment often has many potential sources of 2.4 GHz interference.
- Store demonstration models of cordless phones, baby monitors, and other ISM band devices can cause problems.
- Th inventory storage racks and bins and the inventory itself are all potential sources of multipath problems.
- Heavy user density should also be considered, and a retail site survey should be done in the height of the shopping season as opposed to late January when the
malls are empty.
- Wireless applications that are used in retail stores include handheld scanners used for data collection and inventory control.
- Retail stores may also be looking for a retail analytics solution to monitor customer behavior and trends over the WLAN. Point-of-sale devices, such as cash registers, may also have Wi-Fi radios.
- You may still run into older frequency hopping equipment that may cause all-band
interference with an 802.11b/g/n (2.4 GHz) network. Steps may be necessary to upgrade the older equipment.
- Coverage is usually a greater concern than capacity because wireless data-collection devices require very little bandwidth, and the number used in a particular area is typically limited.
- Some of the earliest deployments of 802.11 technology were in
warehouses for the purpose of inventory control and data collection.
- A 2.4 GHz WLAN will likely be deployed because most handheld devices currently use 2.4 GHz radios. Coverage, not capacity, is usually the main objective when designing a wireless network in a warehouse.
- Warehouses are filled with metal racks and all sorts of inventory that can cause reflections and multipath.
- The use of directional antennas in a warehouse environment may be a requirement if legacy 802.11a/b/g access points are still being used.
- High ceilings often cause mounting problems as well as coverage issues.
- Indoor chain-link fences that are often used to secure certain areas will scatter and block a 2.4 GHz RF signal.
- Seamless roaming is also mandatory because the handheld devices will be mobile.
Forklifts that can move swiftly through the warehouse often have computing devices with Wi-Fi radios.
- Legacy deployments of 802.11 FHSS hardware and/or legacy 900 MHz radios still exist in some warehouse environments. Handheld WLAN barcode scanners are
now often being replaced with smart phones that use barcode scanning applications.
- A manufacturing environment is often similar to a warehouse environment in terms of multipath interference and coverage design.
- However, a manufacturing plant presents many unique site survey challenges, including safety and the presence of employee unions.
- Heavy machinery and robotics may present safety concerns to the surveyor, and special care should be taken so as not to mount access points where they might be damaged by other machines.
- Many manufacturing plants also work with hazardous chemicals and materials.
- Proper protection gear may need to be worn, and ruggedized access points or enclosures may have to be installed.
- Technology manufacturing plants often have clean rooms, and the surveyor will have to wear a clean suit and follow clean room procedures if they are even allowed in the room.
- Many manufacturing plants are union shops with union employees.
- A meeting with the plant’s union representative may be necessary to make sure that no union policies will be violated by the site surveyor team.
- Some of the earliest deployments of 802.11 technology were in
- Multitenant Buildings
- By far the biggest issue when conducting a survey in a multitenant building is the presence of other WLAN equipment used by nearby businesses.
- Office building environments are extremely cluttered with 802.11b/g/n wireless networks that operate at 2.4 GHz.
- Almost assuredly all of the other tenants’ WLANs will be powered to full strength, and some equipment will be on nonstandard channels such as 2 and 8, which will likely interfere with your WLAN equipment.
- If at all possible, strong consideration should be given to deploying a WLAN using the 5 GHz U-NII bands.