Wireless Infrastructure 101

November 23, 2017 at 8:00 AM

 

You would be hard pressed to find a business, industry or home that doesn’t use wireless communication in some way. We depend on wireless networks used by our mobile devices, laptops, tablets and gaming systems to keep us connected, entertained and informed every day. Here, we’ll look at indoor and outdoor wireless infrastructure design considerations.

 

Frequencies

 

For wireless communication to work, radio frequency (RF) and microwaves are used to transmit voice, video and data. Radio frequencies are usually used in wireless networks, they range from 3 kHz to 300 GHz and are also used for AM broadcasting, navigational beacons and shortwave radio. Microwaves range from 300 MHz to 300 GHz and are typically used for television, FM broadcasting, aviation communications, and radar and satellite links. Most home, business and government networks operate on the Industrial, Scientific and Medical (ISM) frequency bands that range from 900 MHz to 5 GHz. The ISM band frequencies incorporate many of the IEEE 802.11wireless standards.

 


Design Considerations

 

When designing a wireless network, you must always take into consideration the environmental variables in the installation area that will or could affect network performance.

 


Indoor RF Wireless Networks

 

During installation or expansion, indoor networks present a special set of factors to consider. Most wireless access points and routers have a typical range capability specified by the manufacturer. But these ranges are based on having clear line of sight, which requires an unobstructed view of the antenna from the remote point in the link. Unfortunately, this is not the case in most indoor installations, there is usually some type of obstacle present. For example, signals typically will not penetrate concrete walls and the other building materials such as metal studs, aluminum siding, foil-backed insulation, pipes, electrical wiring and furniture. All of these common obstacles can reduce signal range and affect the coverage area. Plus, other wireless equipment such as cordless phones, microwave ovens, radio transmitters and electrical equipment can cause interference and decrease the signal range.

 


Outdoor RF Wireless Networks

 

Outdoor wireless networks face many of the same challenges as indoor networks, such as reflections and multipath. Having a clear line of sight is also critical for an outdoor network, trees and leaves can obstruct 802.11 frequencies and block the signal completely. A site survey is recommended before an outdoor wireless network is deployed, it might also be necessary to clear obstacles.

 

To help you plan and design your wireless network, we offer a series of wireless calculators to get you started.

411 on DAS

September 28, 2017 at 8:00 AM

 

If you’ve ever lost your cellular signal in a building that you thought would be covered by your cellular network, you probably would have appreciated the help of a distributed antenna system (DAS). Today’s construction techniques and materials block or weaken internal and external wireless communication signals inside buildings. Blocked radio and cellular reception isn’t only a nuisance for consumers, it can be detrimental to public safety and hinder first responders in an emergency situation. Thus, distributed antenna systems were designed to counteract those effects and extend wireless coverage within structures to allow radios and cell phones to work everywhere within the building.

 

A distributed antenna system uses several small antennas, as opposed to one antenna, to provide wireless coverage and eliminate spots of poor coverage inside a large building. These antennas serve as repeaters and provide reliable coverage within the structure, without requiring much additional power. They provide voice and data services, just like a cellular tower would, without any noticeable difference to mobile device reception. Any densely populated indoor space is a good candidate for DAS deployment, such as shopping malls, medical centers and high-rise buildings. Distributed antenna networks also provide wireless coverage to hotels, subways, airports, hospitals, businesses, roadway tunnels and more. In addition to indoor use, a DAS can be designed to extend wireless coverage for outdoor use. Distributed antenna systems typically provide wireless services that include PCS, cellular, Wi-Fi, police, fire and emergency services.

 

A DAS often uses RF directional couplers and/or wireless amplifiers to split and amplify the wireless signal from the source to the distributed antennas. In many cases, a DAS will use a combination of low-loss coaxial cabling as well as fiber optic cabling to support radio-over-fiber (RoF) technology and distribute the wireless signals to the antennas. The antennas are physically connected to a central controller, which is then connected to the wireless carrier network’s base station. At least one carrier network must be involved with a DAS deployment because the systems operate on the RF spectrum, which is licensed to wireless carriers.

 

Distributed antenna systems can be passive or active. A passive DAS grabs cellular signals from roof antennas and runs them through leaky feeder cables that distribute the signal throughout the building. An active DAS passes the signal from the roof antennas through fiber cables, boosting and amplifying the signals as needed.

 

Deploying DAS is the most expensive aspect of the project, as it can be very labor intensive to install the antennas and run cables between antenna modules and the controller. Usually, the carrier network manages the cost and maintenance of the DAS system, as long as it aligns with their network plan and fills a significant gap in service. Responsibility for a distributed antenna system may be shared by multiple carriers to keep costs down.

 

© L-com, Inc. All Rights Reserved. L-com, Inc., 50 High Street, West Mill, Third Floor, Suite 30, MA 01845