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.

The Low Down on Low-Loss Coax Cables for Wireless Applications

August 17, 2017 at 8:00 AM

 

It may seem counterintuitive that a wireless network would need cables, but it’s true. The components of a wireless network, such as access points, amplifiers and antennas, all need cables to communicate with one another. Antenna cables introduces signal loss in the antenna system for both the transmitter and receiver. In order to reduce this signal loss, you need to either minimize the cable length, if you can, and use only low-loss or ultra-low-loss coax cable s in order to connect access points and amps to antennas.

 

Coaxial cable is one of the oldest signal cabling types and is still used today because it is robust and very good at carrying a signals over long distances. The term coaxial comes from the inner conductor and the outer shield sharing a geometric axis. The term "low-loss" refers to the cable's relative low-attenuation (loss) over distance. The general rule is that the thicker the cable is, the less loss of signal there will be over the length of the cable.

 

RG-style cables were the original standard for coaxial cable, but the signal in these cables degrades over longer distances. This isn’t an issue when covering short distances, but in a wireless application it is critical to maintain the signal strength throughout the cable and until it is sent out through the antenna. Thus, low-loss coaxial cable was created offering lower attenuation and better shielding, a much better solution for wireless systems than RG-style cables. Low-loss coaxial cables also use solid center conductors which provide lower attenuation than the stranded conductors found in some types of RG-style coax cables.

 

Low-loss coaxial cables are ideal for use in WLAN, Cellular, PCS, ISM and many other wireless communications applications. They are offered in multiple sizes with a three-digit “series” number designating the thickness of the cable and the low-loss properties. For example, 400-series low-loss coax is thicker and has less loss than 200-series, and 200-series is thicker and has less loss than 100-series. While the thicker cable will provide less loss, it will also be heavier and less flexible, though ultra-flex versions of the thicker series cables do offer more flexibility.

 

Here is a comparison chart for popular types of low-loss coaxial cables:

Pros and Cons of the ISM Band Frequencies

November 26, 2015 at 8:00 AM

 

900, 2,400, 5,000 – these are not factors in an algebraic algorithm.  These are the unlicensed frequency bands that have helped propel the growth of the wireless industry.

 

In the US, the 900, 2,400 and 5,000 MHz frequency bands are set aside by the FCC for unlicensed Industrial, Scientific and Medical (ISM) applications. Each ISM band frequency is allocated for a different purpose. They are used for consumer and commercial Wi-Fi and WLAN applications as well as commercial Radio Frequency Identification (RFID) and Supervisory Control and Data Acquisition (SCADA) applications.

 

Here, we take a closer look at the pros and cons of each frequency.

 

900 MHz


What the 900 MHz band lacks in bandwidth, it makes up for in distance. This frequency is very narrow which limits its maximum data rates, though it is able to penetrate obstructions such as tree and leaves in the Line-of-Sight (LOS).

  

The 900 MHz band is commonly used by applications such as SCADA and RFID which have lower data rate requirements than applications found in the 2.4-5 GHz frequency bands. The type of data packet usually sent in these applications is a simple on/off command to a motor or a valve, for instance.

 

The 900 MHz frequency surpasses other bandwidths with its ability to penetrate obstructions such as trees and leaves in the Line-of-Sight.  For example, the 2.4 GHz band is absorbed by water found in trees and leaves which causes path loss of the transmission. Thus, 900 MHz is often used for Non-Line-Of-Sight (NLOS) applications.

 

2.4 GHz


2.4 GHz is the frequency of choice for the home user and commercial businesses. It is the primary band used for cordless phones, microwave ovens, baby monitors, Wi-Fi, Bluetooth, printers, keyboards and gaming controller applications. Voice, video and data communications are typically used in 2.4 GHz systems requiring higher data rates of up to 300 Mbps for 802.11n applications.

 

As the most widely used frequency, the 2 .4 GHz band can become overcrowded. When excessive overcrowding occurs, Wi-Fi network signal may be weak or not work at all. In some cases, it's best to connect 2.4 GHz Wi-Fi networks using backhaul links on the less crowded 5 GHz frequency.

 


5 GHz


The 5 GHz frequency is often used in commercial Wi-Fi applications. It is also the frequency used for the emerging 802.11ac standard which will provide up to 1.3 Gbps of wireless data throughput.  802.11n can also use the 5 GHz frequency. On the flip side, this super-speed band has the shortest range of all three ISM frequency options.

 

There you have it, the good and the bad of each ISM frequency.  Now you know all the factors to consider when choosing the best band for your application.

 

 

 

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