WiFi Alphabet Soup

December 17, 2015 at 8:00 AM

 

In 1997 the Institute of Electrical and Electronics Engineers (IEEE) released the first 802.11 WiFi standard, 802.11-1997. Since then there have been several follow-on releases that have brought improvements in speed, range and capacity.

 

Here, we give you the A to Z on the 802.11 standards. 

 

Old School WiFi

 

Once widely implemented, especially in business networks, 802.11a supports data rates up to 54 Mbps. It utilizes the 5 GHz frequency band, which has significantly less congestion than other bands and less interference from other devices ensuring better signal integrity and fewer dropped connections. One disadvantage of 802.11a is that its effective overall range is slightly less than that of 802.11b and 802.11g. 802.11a signals are more readily absorbed by walls and other solid objects compared to 802.11b/g.

 

802.11b was released in 1999; the same year 802.11a was released. 802.11b access points, interface cards etc. were less expensive than 802.11a equipment which made it affordable for use in home and small business networks. 802.11b is better at penetrating solid objects such as walls compared to 802.11a but its maximum throughput is only 11 Mbps compared to 802.11a’s 54 Mbps. For outdoor networks 802.11b is not as effective as 802.11a at penetrating trees and leaves as it operates in the 2.4 GHz frequency band. 2.4 GHz signals are absorbed by water found in trees and leaves limiting overall outdoor range.

 

Adopted in 2003 with the promise of higher data rates and reduced cost, 802.11g also operates in the 2.4 GHz frequency band. 802.11g supports a maximum throughput of 54 Mbps and is backward compatible with 802.11b devices/networks. 802.11g experiences the same interference issues as 802.11b as it operates in the crowded 2.4 GHz range. Examples of devices that operate in the 2.4 GHz band include microwave ovens, baby monitors, Bluetooth devices and cordless telephones not to mention a multitude of other 802.11b/g access points.  

 

New School WiFi

 

802.11n, released in 2009, was developed to improve network throughput by utilizing multiple antennas to increase data rates. This standard uses both 2.4 GHz and 5 GHz bands and provides high data throughput of up to 600 Mbps. Additionally 802.11n provides superior indoor and outdoor coverage, essentially doubling the range of its predecessors 802.11b/g.  

 

 

802.11n uses Multiple-input Multiple-output (MIMO) technology which is a technique for sending and receiving more than one wireless signal on the same radio channel at the same time which increases overall throughput (up to 600 Mbps!)

 

The most recently released version of the 802.11 standard is 802.11ac. 802.11ac supports data rates of up to 1.3 Gbps! 802.11ac operates solely in the 5 GHz band, supports MIMO technology and can handle up to four spatial streams (Wave 1) along with wide 80 MHz (Wave 1) channels. 802.11ac also has the advantage of multi-user MIMO or MU-MIMO which is an advanced form of MIMO where an access point can send data to up to four client radios at the same time directing a separate spatial stream to each one compared to 802.11n access points that can only communicate to one client at a time. By implementing MU-MIMO overall WiFi network efficiencies are realized even as more clients are added to the network.

 

Weighing the pros and cons of the different 802.11 standards and being well-versed in the 802.11 vocabulary will help you make an informed decision when planning your next WiFi network.

 

Click on the image below to download our handy 802.11 standards reference chart.

 

 

Can You Define Antenna Gain?

July 24, 2014 at 10:00 AM

 

"What is gain?" 

 

Many of our customers ask us this question. 

 

In fact, it has become so common that we created a Wireless Glossary to explain “gain” along with other common wireless terms.

 

But, the term “gain” is tricky to define, so we're going to dig into it a bit more here.

 

One of the major parameters used in analyzing the performance of radio frequency (RF) communication is the amount of transmitter power directed toward an RF receiver.

 

This power is derived from a combination of:

 

1.Transmitter power

2.The ability of the antenna(s) to direct that power toward an RF receiver(s)

 

 

 

Directivity

 

The directivity of the antenna is determined by the antenna design. Directivity is the ability of an antenna to focus energy in a particular direction when transmitting or to receive energy better from a particular direction when receiving. To determine the directivity of an antenna, we need a reference antenna with which to compare our antenna's performance.

 

Omni Directional:
360° Coverage

Directional:
Focused Coverage

 

 

Over the years there have been several different reference antennas used to determine directivity; however, today an isotropic radiator is preferred as the standard antenna for comparison. The isotropic antenna transmits equal amounts of power in all directions (like a light bulb).

 

To increase the directivity of a bulb's light (or the antenna's energy)- similar to a flash light or automobile head lamp in this example- a reflector (antenna) is added behind the bulb. At a distance the light bulb now appears to be much brighter in the light beam. The amount that the bulb appears brighter compared to the bulb without a reflector is the directivity of the reflector (antenna).

 

When directivity is converted to decibels we call it the “antenna gain” relative to an isotropic source (dBi). Typically the higher the gain, the more efficient the antenna's performance, and the farther the range of the antenna will operate. For every 6 dBi in gain, you double the range of the antenna.

 

It should also be noted that many factors need to be considered when selecting the "best" antenna for the desired application, and it’s best to discuss any antenna selection with someone knowledgeable in RF radiation and antenna performance. L-com has experts to help you make the best selection for performance and price to fit your application.

 


 

Helpful definitions to summarize our topic:

 


Antenna Gain: A relative measurement of an antenna's ability to direct or concentrate radio frequency energy in a particular direction or pattern. This measurement is typically measured in dBi (Decibels relative to an isotropic radiator) or in dBd (Decibels relative to a dipole radiator).

 

Isotropic Radiator: is a theoretical single point in space that radiates energy equally in every direction similar to the Sun radiating its light. The isotropic radiator exhibits the same magnitude or properties when measured in all directions. It has no preferred direction of radiation. It radiates uniformly in all directions over a sphere centered on the source.

 

 

Check out some of our best selling antennas!                                                                     

 

 

Don’t Plan a WLAN Until You Read Our WiFi Antenna White Paper

April 3, 2014 at 10:00 AM

 

Why? Let me ask you this.

 

Do you know how to choose the correct antenna for a better wireless connection?

 

With all of the various antenna options out there, it can get confusing as to which antenna to use and how they work. After reading this white paper, you’ll have the information you need to get started on planning your network. 

 

Our white paper - Choosing the right WiFi antenna for your applicationcovers common wireless network application examples and details the basic types of WiFi antennas that are available today. From choosing an antenna for a campus, to planning for an office environment, we give you a rundown of what antenna is best for your application and how-to tips for proper network design.

 


Here are just a few highlights from this free white paper:

 


There are two main types of WiFi antennas, Omni directional and directional

 

Omni directional antennas provide a 360° donut shaped radiation pattern to provide the widest possible signal coverage in indoor and outdoor wireless applications. An analogy for the radiation pattern would be how an un-shaded incandescent light bulb illuminates a room. Types of omni directional antennas include "rubber duck" antennas often found on access points and routers, omni antennas found outdoors, and antenna arrays used on cellular towers. ... (read more)

 

Outdoor Omni Antenna

Rubber Duck Antenna

Omni Antenna Array

I want to add WiFi to my office building (inside)

 

To provide wireless coverage to an inside office space, use omni directional antennas that provide 360° wireless coverage. The style of antenna typically used is the ceiling mount omni directional antenna. The antenna gain pattern for the ... (read more)

 

 


I want to install WiFi in a campus environment (outside)

 

In this case you can use several directional antennas with an omni directional antenna at the central building to connect the buildings in the campus. This is called a point to multipoint network. As with any outdoor WiFi network, clear ... (read more)

 


 

to download this free white paper 

 

802.11ac: What’s all the buzz about?

March 13, 2014 at 10:00 AM

 

Amidst the bustling and overpopulated race to find better, faster WiFi, there now exists a new wireless standard that will help you get there. You may even come in first place.

 

The latest IEEE standard for wireless networking, 802.11ac, is bringing high speed gigabit wireless connectivity to business, home, and government communications systems everywhere. 802.11ac offers up to 1 Gbps wireless transmissions and the ability to support up to eight MIMO spatial streams as well as 80 MHz channel bandwidth. This new advancement in wireless technology promises flawless voice, video, and data transmission to multiple end users at the same time.

 

If slow WiFi has you feeling down, 802.11ac is worth looking into.

 

802.11ac delivers faster throughput and better range than the previous 802.11n standard. 802.11n can deliver up to 600 Mbps with four spatial streams using one 40 MHz-wide channel. 802.11ac is engineered to deliver up to 1Gbps which translates to higher data rates and happier end users.

 

The new amendment’s ultimate intention is to achieve higher multi-user throughput in wireless local area networks (WLANs) and improve WLAN user experience especially for bandwidth intensive applications such as streaming voice and video.

Here at L-com, we continue to support the latest standardized technologies by offering high quality, high performance products, including those for 802.11ac applications.

 

Our series of 802.11ac indoor and outdoor WiFi antennas feature 2.4-5.8 GHz operation for a variety of applications. L-com currently offers 802.11ac ceiling antennas, panel antennas, rubber duck antennas, and Omni antennas.

 

Wireless LOS Terminology

November 28, 2013 at 10:00 AM

Why Line of Sight (LOS) is so important

 

Sample of LOS and Fresnel Zone Diagram

When designing an outdoor wireless network, ask yourself this: what is between point A (antenna 1) and point B (antenna 2)? This path between two antennas is referred to as the Line of Sight (LOS).

 

There are three main categories of Line of Sight. Full Line of Sight (LOS) is where no obstacles reside between the two antennas. Near Line of Sight (nLOS) includes partial obstructions such as tree tops between the two antennas. Lastly, Non Line of Sight (NLOS) is where full obstructions exist between the two antennas.

 

By determining the specific Line of Sight conditions in the WiFi network area you can then determine the correct type of wireless system to install.

 

Another common term to be aware of is The Fresnel Zone, referenced in the diagram above. It is is an electromagnetic phenomenon where light waves or radio signals get diffracted or bent from solid objects near their path. The radio waves reflecting off the objects may arrive out of phase with the signals that traveled directly to the receiving antenna, thus reducing the power of the received signal.

 

Line of Site (LOS) Overview Diagram

Print and post the above diagram.

 

For indoor wireless network installations it is important to consider obstacles such as walls, ceilings, and furniture that will affect Line of Sight since these all play a role in wireless signal reception. In wireless transmissions, reflections (when wireless signals "bounce" off objects) and multipath (when wireless signals travel in multiple paths arriving at the receiver at different times) are as important as signal strength in determining the success of an installation. A signal will also exhibit peaks and nulls in its amplitude and alteration of its polarization (vertical or horizontal) when propagating through walls, ceilings and reflecting off metallic objects. 

 

Path Loss is another area of concern when dealing with Line of Sight. For instance, although 2.4 GHz signals pass rather well through walls, passing through trees and leaves is a challenge. This is due to the difference of water content in each. Radio waves in the 2.4 GHz band absorb into water very easily, so the high level of moisture in trees or leaves would trap the waves. When faced with nLOS or NLOS conditions due to trees, 900 MHz is your best choice as it is not absorbed like 2.4 GHz.

 

 

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