Page 20 - Security Today, October 2017

Providing a Network Link What you need to know about outdoor wireless access points
BOy Emily Chae and Evan Davis
utdoor 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 of- fice building, or share Internet and network access with another building on your campus. Outdoor ac-
cess 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 wire- less bridge that allows two separate buildings (or locations) to net- work and communicate with each other. Like all IP devices, an out- door 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 wire- less 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 applica- tion 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-de- grees, to and from all directions. Directional access points communi- cate 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 cor- rectly 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 om- nidirectional access point for best results. Using a directional access point reduces the area where wireless signals are sent. Wireless range
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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 stan- dard 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 sol- ids 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 one- third mile to five miles. This is assuming that there is a line of sight to each access point with no obstructions or interference.
WIRELESS TECHNOLOGY
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