Providing a Network Link

What you need to know about outdoor wireless access points

• By Emily Chae, Evan Davis
• Oct 01, 2017

Outdoor wireless bridges are used to provide a network link from one location to another. You may want to network surveillance cameras back to your main office building, or share Internet and network access with another building on your campus. Outdoor access points are used to create these wireless bridges, but they can also be used to provide Internet access outdoors.

The primary purpose of outdoor access points is to create a wireless bridge that allows two separate buildings (or locations) to network and communicate with each other. Like all IP devices, an outdoor access point functions both as a transmitter and a receiver; it will send and receive data simultaneously. Two or more access points are required to create a point-to-point or point-to-multi-point wireless bridge links.

Wireless bridging is a common application for surveillance solutions with a remote end point, such as another building or a pole in parking lot or open public area. A less common application is to use an outdoor access point to provide wireless access to client devices (phones, tablets, laptops, etc.) outdoors, such as in a patio area or your home’s backyard. The wireless range is strictly limited by the capabilities of each client device, so each user may have a different experience.

Site Surveys

Before you get started on any networking project, a site survey must be completed. A site survey is crucial to planning and designing a wireless network; it helps to determine the necessary parameters to meet the requirements for the network.

Site surveys help to determine requirements for a specific application or project, including network capacity, wireless coverage, data rates, and radio interference. A site survey also helps to determine the best locations to install each of the access points.

Be sure to analyze floor plans, inspect the site location, and meet with the IT management team before you get started with the installation process. Site surveys also include testing, auditing, analysis and diagnostics of the existing network to help determine what is required for the level of service demanded. When deciding mounting locations, keep in mind to consider the polar plot and the radius.

There are several free tools available including computer software and mobile apps. However, it’s not recommended to use a mobile phone to conduct a site survey; using a laptop is preferred over a mobile device due to radio strength. For the best analysis, select one of the several professional tools available on the market.

Omnidirectional vs. Directional

Omnidirectional access points receive and transmit signals 360-degrees, to and from all directions. Directional access points communicate back and forth in the same direction.

Omnidirectional access points are most common where there are multiple buildings with one building used as the main hub or center. Omnidirectional access points also come in handy when there is no clear line of sight (more on this below).

When working with directional APs, be sure you install them correctly at an appropriate height and angle. Directional APs must have line of sight and be pointed directly at each other to work.

Outdoor wireless applications for client devices require an omnidirectional access point for best results. Using a directional access point reduces the area where wireless signals are sent. Wireless range will be limited by the maximum wireless range of a client device.

PoE vs Proprietary/Passive PoE

Power over Ethernet or PoE allows you to use a single cable to deliver both power and data. Utilizing PoE allows you to save on installation costs and time; there’s only one cable to buy, and only one cable to run.

PoE standards are set by the IEEE organization. Standard PoE (802.3af) provides up to 15.4 watts of power per port; PoE+ (802.3at) provides up to 30 watts of power. Ultra PoE, or UPoE, is a new standard developed to handle up to 60 watts of power.

However, it is not uncommon for high-power outdoor access points to use proprietary or passive PoE. This is especially useful for PoE devices that require more power, such as advanced speed dome cameras with heating or other features. Devices that require the use of proprietary or passive PoE usually include a PoE injector which allows you to easily integrate the device with the rest of your PoE devices and network.

Ingress Protection Ratings

The Ingress Protection Rating (IP Code, International Protection Marking) identifies the level of protection a product has against solids and dust. Most outdoor AP housing will have an IP rating such IP55, IP66, or IP67. The first number is related to solids, and the second is related to liquids. For most applications, a five or six rating on both solids and liquids will be sufficient for outdoor applications.

Outdoor Wireless Range and Bandwidth

Standard range for an outdoor wireless bridge is approximately onethird mile to five miles. This is assuming that there is a line of sight to each access point with no obstructions or interference.

Useable Distance and Bandwidth

There are many factors that can affect the useable distance and bandwidth of wireless bridge solutions. Physical obstructions, radio interference, and physical placement all play important roles. Carefully select mounting location and height to avoid physical obstructions. The site survey you conducted will help you avoid interference from other devices and determine the ideal locations.

In regards to radio interference, the 2.4GHz band is the most commonly used and often the most saturated radio frequency. In addition to wireless access points, many other common devices operate on the same 2.4GHz radio frequency, such as cordless phones, baby monitors, microwave ovens, and car alarms. Try using a different channel, moving the AP to a location with little to no interference, or use an AP that supports the less congested 5GHz band. Remember that a site survey is required to help you choose the best location.

Distance or wireless range can also be increased by using a lower performing wireless band, however wireless n is the lowest wireless band you’ll want to use for today’s applications. Distance is also dictated by the weaker radio specification. For best results, use the same model access point for your point-to-point bridge installation.

The FCC (and other government organizations) limits the transmit power of wireless products, which directly effects the maximum wireless range. Some access points use uncommon and/or unlicensed frequencies to increase the distance or range. Using an unlicensed frequency has its benefits, but it locks you into a specific brand since it uses a unique and/or uncommon frequency.

For outdoor access points that are used to provide internet access to client devices, the range is limited by the client device and not the access point itself. On average, the range for client devices will be 50-300 feet.

Line of Sight

When installing access points, ensure that there is a direct line of sight from one AP to the other AP. There should be no obstructions of any kind, including other buildings or trees. If line of sight is compromised, there are alternative installation methods to consider such as wireless repeating, hub and spoke (point to multiple point), or adjusting installation location.

Wireless repeating or wireless hopping is where the connection is repeated from Building A to Building B to then reach Building C. Daisy chaining is not a recommended option as bandwidth will be lost with each wireless touch point. Depending on your application, it is not recommended to repeat more than once. Be sure you have enough bandwidth for your specific project.

This article originally appeared in the October 2017 issue of Security Today.