Alpha Omega Wireless Blog

The Coming Flood of Unlicensed Wireless Bridge Radios

Posted by Joe Wargo on Tue, May 11, 2010 @ 01:50 PM

If you thought wireless interference among unlicensed wireless Ethernet bridge systems is bad now, just wait. What's going to cause this flood of wireless interference is the introduction of 802.11n based, OFDM and MIMO, outdoor wireless backhaul systems. Add to the mix the amount of wireless backhaul being deployed in the IP video surveillance industry.

Wireless Interference Spectrum Analysis
Microwave communication using unlicensed wireless Ethernet bridge systems have been an extremely popular choice for outdoor wireless backhaul. Many Point to point wireless backhaul, point to multipoint wireless Ethernet bridges, wireless mesh, and outdoor Wi-Fi systems use unlicensed wireless spectrum. The unlicensed spectrum of 5GHz (5.3GHz, 5.4GHz, and 5.8GHz UNII bands) became a primary selection by many end users and outdoor wireless installation VAR's, because of their flexibility, cost effectiveness, rapid ROI, and quick deployments. Unlike a licensed microwave link, which can take several weeks to acquire a license, purchase and install, an unlicensed point to point wireless Ethernet bridge can be purchased and installed literally in a day or two.

Point to multipoint wireless backhaul and wireless mesh networks are primarily in the unlicensed 5GHz. Note: with a few exceptions of the 4.9GHz public safety band and now with the 3.65GHz WiMax backhaul spectrum. Many outdoor wireless manufactures started introducing "value line" point to point wireless Ethernet bridges using 802.11 chipsets. Basically, the same radio boards found in Wi-Fi access points put into an outdoor enclosure and using outdoor wireless antennas. The point to multipoint wireless bridge and wireless mesh backhaul systems all use the same 802.11 architecture. Some manufacture has changed the protocols to 802.16 standards or use a proprietary protocol, but they are all Atheros based (or equivalent) chipsets under the hood.

The value in these chipsets is the cost of deploying an outdoor wireless backhaul has come way down. The problem of these systems being so cheap is that many end users (non-trained outdoor wireless professionals) have started to deploy their own outdoor wireless bridges. Back in the day the wireless installation of Enterprise grade unlicensed wireless backhaul radios was done by outdoor wireless professionals that knew how to use the right antennas, power settings, and methods to help avoid wireless interference on their clients' wireless bridge as well as other wireless backhaul users in the area.

Many of the low cost wireless bridge radios come with integrated wide beam antennas (7 to 11 degree beam width on panel antennas, 30-60-90 degree beam width on sector antennas, and 360 degree omni-directional antennas) and have default power output settings set to max (which most forget to turn down where not needed).

Now with the acceptance of 802.11n chipsets there has been a mad rush by the outdoor wireless manufacturers to introduce higher bandwidth point to point wireless backhaul, point to multipoint wireless bridges, and wireless mesh systems. Why not? It's pretty amazing that you can now buy an unlicensed wireless Ethernet bridge system that can provide up to 300Mbps of aggregate throughput for under $5,000.00

So what's the issue? In my article "Wireless Interference - The Effect on Unlicensed Wireless Backhaul" we discussed how wireless interference on unlicensed wireless Ethernet bridge systems has continued to grow. The new 802.11n based wireless backhaul radios use OFDM and MIMO taking advantage of multipath, especially helpful in nlos (non line of sight) applications. They also produce a lot of multipath! They also need to use a wider channel width to obtain a higher data rate, up to 40MHz wide. Because these systems, according to manufacture specifications and marketing, can produce high aggregate throughput at an attractive price many people that didn't use outdoor wireless bridge systems are now starting to.

Wireless InterferanceAs more and more people get tempted with the thought of 100Mbps, up to 300Mbps providing an extremely fast ROI compared to a leased telco line, more and more unlicensed wireless backhaul will be deployed. The one thing that that people don't understand is that to get the full throughput the system must run at full modulation and channel width with limited wireless interference. This is something that the manufactures forget to mention. Because people are not controlling their RF signals by deploying so called plug and play outdoor wireless bridge systems and using wide beam antennas at full transmit power the amount of interference is going to explode.

Add into the mix the amount of wireless backhaul for video surveillance. Wireless video backhaul is a huge topic and growing industry. Each year at the popular industry trade event, CTIA, there is a growing number of manufactures displaying their unlicensed wireless video backhaul systems. Using wireless backhaul for video is a great application. But with the large number of unlicensed wireless Ethernet bridges being deployed and the amount that is done improperly the amount of wireless interference is bound to grow.

Should you consider an unlicensed wireless Ethernet bridge, using OFDM and MIMO? These types of outdoor wireless Ethernet bridges provide a great inexpensive solution. They work extremely well on challenging near-line-of-sight and non-line-of-sight applications. They also provide a great amount of throughput at a great price. If you need a true enterprise point to point wireless bridge and have line-of-sight (LOS) there is no substitution to a licensed microwave link, see "Licensed Microwave Wireless Backhaul."

The one thing to keep in mind is prior to considering an unlicensed wireless Ethernet bridge for microwave communication a wireless site survey, spectrum analysis, and a proper wireless path calculations should be performed. As with any point to point wireless backhaul, point to multipoint, or wireless mesh system a certified expert should perform the wireless installation.

Tags: Point to Point Wireless, General, Un-lincesed Wireless, Wireless Industry, Point to Multipoint, wireless mesh

WiMax Backhaul – What it is and what it’s not, Part 2

Posted by Joe Wargo on Mon, May 03, 2010 @ 02:04 PM

From Part 1, we described how WiMax backhaul is a point to multipoint wireless backhaul technology used to create high bandwidth wireless Ethernet bridges between a Base Station Unit (or an array of BSU's) to a Subscriber Unit (or CPE device). WiMax backhaul in the USA, according to the regulations of the FCC, is 50MHz wide of the 3.65GHz frequency band and is a non-exclusive use of microwave wireless, although a service provider must register the wireless bridge broadcast. In other countries the unlicensed wireless 3.5GHz band is common. Licensed microwave 2.5GHz is used by some carriers.

Service providers have adopted WiMax backhaul as a technology that they could readily deploy cost effectively to provide the last mile fixed wireless connectivity with greater bandwidth. It wasn't until later that WiMax backhaul evolved to the mobile carrier space. WiMax currently is a competing 4G technology to LTE (note: see article "WiMax Outdoor Wireless Bridges versus LTE Wireless Networks" for more detial). There are a lot of articles on whether WiMax and LTE truly compete or will end up being complimentary technologies providing different service benefits. The one issue with WiMax is because of the higher frequency bands it does not do well with penetrating obstructions like passing through walls of a building providing coverage indoors. The use of OFDM and MIMO do allow for (NLOS) non-line-of-sight wireless connectivity outdoors.

WiMax backhaul does not compete with the Wi-Fi standards, nor does it replace it. There will continue to be the need for Wi-Fi indoors and around campus environments to provide network connectivity to the LAN. WiMax backhaul will allow mobile device to get high speed internet from the carrier service provider companies that the devices are associated with (such as AT&T, Verizon, T-Mobile, Sprint, etc.).

The bottom line is WiMax backhaul is truly for service providers and mobile carriers. WiMax is not a solution for an end-user. The technologies used by WiMax have already been used for years now (e.g. OFDM and MIMO). WiMax is not a licensed microwave wireless solution that will completely avoid wireless interference. Nor will WiMax backhaul replace point to point wireless backhaul, licensed microwave links or unlicensed wireless Ethernet bridges. Because of the small channel width available currently, WiMax doesn't bring any higher bandwidth for an end user application. The WiMax 2 initiative takes more advantage of the use of MIMO and will provide more bandwidth, like wireless Ethernet bridges that use 802.11n chipsets today.

Today there are many systems that can produce higher wireless backhaul bandwidth by using standard unlicensed wireless Ethernet bridges compared to using WiMax as a wireless backhaul solution. Many manufactures have cashed in on the WiMax standard and have over sold its capabilities and what it's for to the end user market place.

If you are not a mobile carrier or a service provider (WISP), WiMax backhaul does not provide you any advantages over other outdoor wireless Ethernet bridge systems that have been deployed for many years now. To register WiMax is pretty difficult in many areas because many WISP and mobile carriers already have taken the spectrum. Note: see image below showing the areas already registered by service providers and mobile carriers in the Sacramento and San Francisco, CA area.

WiMax Backhaul Coverage

If you need a point to multipoint wireless backhaul solution there has been for years wireless equipment that have the same benefits of WiMax, such as OFDM and use MIMO, that can actually provide much greater bandwidth ( now up to 300Mbps).

Is WiMax good for you? As a mobile user it will provide us great wireless backhaul throughput to our mobile devices. For end users that need another internet provider solution, especially in areas where they can't get DSL, WiMax will allow service providers to provide a high quality wireless Ethernet bridge to areas that were either technically difficult or too costly to provide connectivity to. But for Government, Enterprise, or Private networks it does nothing!

Tags: Point to Point Wireless, Licensed wireless, General, Un-lincesed Wireless, Wireless Industry, Point to Multipoint, WiMax, Wireless 101

WiMax Backhaul – What it is and what it’s not, Part 1

Posted by Joe Wargo on Mon, May 03, 2010 @ 02:02 PM

Many customers come to us and say that they need a wireless backhaul solution, but say they are waiting for WiMax. We ask, "Why?"

Many people that are not part of (or don't closely follow) the wireless backhaul, point to point wireless bridges or point to multipoint wireless backhaul, industry or the 4G mobile (LTE and WiMax) carrier industry really don't understand what WiMax is all about. Some think it's a Wi-Fi replacement. Others think it's a new technology that is going to replace all outdoor wireless backhaul, like licensed microwave links or wireless mesh networks. There is a lot of talk about the standards-based technology of WiMax backhaul. Many people do not know what WiMax is or what WiMax is not.

The term WiMax has become a marketing machine and has pushed the outdoor wireless backhaul industry into one the fastest growing technology industries. Just as the term Wi-Fi has been trademarked to the indoor wireless LAN market, WiMax is a trademarked term for a standards-based point to multipoint technology for the outdoor wireless backhaul market. WiMax in itself is not encompassing of all outdoor wireless backhaul. Note: image below is reported by the WiMax Forum as of Feb, 2010.

WiMax Deployments Worldwide

A General Background:
WiMax backhaul was originally designed to be a point to multipoint wireless backhaul solution for providing last mile wireless Ethernet bridges, as alternative to DSL to the home and T1 replacement to businesses. A point to multipoint wireless system consists of a base station unit ("BSU") or sometimes called an Access Point ("AP"), as a standalone or part of a cluster to provide multiple sectors of wireless backhaul coverage that provides wireless backhaul to multiple Subscriber Units ("SU"). SU's are sometimes called CPE's (customer premise equipment). This was for the WISP and telecommunication provider markets.

Part of the equation was also to make mobile devices (like laptops and mobile phones) equipped with WiMax 802.16 chipsets so they could become an actual subscriber unit, creating direct internet access through the service provider (like a giant outdoor hot spot). This would basically provide a direct wireless Ethernet bridge connection directly to a WiMax point to multipoint wireless base station array. Like a mobile phone connecting to a cellular tower.

Manufactures of outdoor wireless bridges and the WISP market realized that wireless interference is a huge issue with outdoor Ethernet wireless bridges. When you start using unlicensed wireless bridges to be a point to point wireless backhaul to unlicensed point to multipoint wireless bridges, which then provide backhaul for Wi-Fi access, in unlicensed 2.4GHz (802.11b/g/n) and 5.8GHz (802.11a/n), there is a large risk of wireless interference. At the same time many people have tried to extend Wi-Fi to outdoor environments to provide greater wireless connectivity to mobile devices, but this still needs a backhaul at some point.

WiMax backhaul was originally going to be in a frequency band away from the popular 5GHz band (5.3GHz, 5.4GHz, and 5.8GHz) used for most unlicensed wireless bridges. Unfortunately, the FCC did not allow for this. Later the FCC did open up a small piece of spectrum, 50MHz wide, of the 3.65GHz band to be used by WiMax backhaul radios. The 3.65GHz band is non-exclusive, meaning it's not a licensed microwave bridge requirement, but just a lightly regulated space that requires service providers to register the microwave wireless broadcast. The 3.5GHz band is used for WiMax backhaul wireless radios in other countries. Some mobile carriers have manufactured their own radios to operate in their licensed 2.5GHz frequencies.

For a piece of wireless backhaul equipment to be considered WiMax Certified (by the WiMax ForumTM) it must comply with the 802.16 IEEE standards and be completely interoperable with other manufactures WiMax equipment. The problem is that there are not many devices that are truly interoperable or have been fully tested to work with one another. It's funny how many of the WiMax 802.16 standards, like OFDM, were already found in the existing product lines or outdoor wireless Ethernet bridge manufactures like Proxim, Alvarion, Motorola, and others. Most WiMax equipment is almost no different than current point to multipoint wireless systems operating in the 2.4GHz or 5.8GHz unlicensed wireless bridge frequency bands. Most use OFDM and MIMO technologies. WiMax backhaul just operates in a different 3.65GHz wireless band, which provides a smaller channel width and less data throughput.

More to come in Part 2...

Tags: Point to Point Wireless, General, Un-lincesed Wireless, Wireless Industry, Point to Multipoint, WiMax, Wireless 101

Non Line of Sight Point to Point Wireless Backhaul

Posted by Joe Wargo on Fri, Apr 23, 2010 @ 01:42 PM

Does an outdoor wireless point to point bridge require Line-of-Sight ("LOS") or can a quality wireless Ethernet bridge perform under Non-line-of-Sight ("NLOS") conditions? LOS is when both antennas in a outdoor wireless bridge system must have clear visibility with one another and have no encroachments to the first Fresnel Zone. In a NLOS situation there is either limited visibility from one wireless antenna to the other (near-line-of-sight or" nLOS") caused by a Fresnel Zone encroachment or complete obstruction blocking the visibility between the two wireless antennas.

NLOS wireless backhaul
The answer depends on the individual path and the throughput requirement. In many cases, if the wireless design and wireless installation is done properly a quality NLOS microwave link will provide good quality high bandwidth.

General Overview of Point to Point Wireless Backhaul:

A typical outdoor wireless backhaul is used to pass higher throughput over greater distances. Outdoor wireless bridges operate in the SHF (Super High Frequency) band in unlicensed wireless backhaul 5.3GHz, 4.9GHz, 5.4GHz, 5.8GHz, and 24GHz or licensed microwave backhaul 6GHz, 11GHz, 18GHz, and 23GHz. There is also unlicensed 60GHz and registered 80GHz millimeter wave in the EHF (Extreme High Frequency) band. The unlicensed wireless Ethernet bridges typically provide from 10Mbps to 300Mbps aggregate throughput. Unlicensed 24GHz and licensed microwave links offer up to 360+Mbps Full Duplex. 60GHz and 80GHz wireless bridge systems can provide up to GigE Full Duplex (gigabit wireless). The higher frequencies do not do well with penetrating obstructions.

For an outdoor wireless bridge to work the system gain must be greater that the total Path Loss. Historically, an outdoor wireless bridge required LOS providing first Fresnel Zone clearance. By having no obstructions in the first Fresnel Zone the receive signal are optimized and the out of phase signals are minimized.

General Overview of Non-Line-of Sight Wireless Bridges
When considering a point to point wireless backhaul, whether a licensed microwave link or an unlicensed wireless Ethernet bridge, one of the first questions asked is if there needs to be LOS to get a microwave link. Many don't understand the difference between wireless bridge technologies that they are use to (like cellular and cordless phones or Wi-Fi) compared to an outdoor point to point wireless Ethernet bridge.

Devices like cellular operate in a range from 800MHz to 1900MHz of the UHF (Ultra High Frequency) band. These frequencies do well with penetrating obstructions but have limited throughput capabilities. Most Wi-Fi operates in the 2.4GHz frequency of the UHF band and can provide higher bandwidth but is very limited in distance. Microwave communication signals are highly attenuated by an obstructed path. In a NLOS microwave link the RF signals will get to a destination by: diffraction around an object, reflection off objects, or by penetration through the obstruction.

For an outdoor wireless bridge, being used for high bandwidth, point to point backhaul to work in a NLOS application there are several requirements that need to be met. Proper power budget, fade mitigation, adaptive link characteristics, and proper demodulation in regards to dispersion. Because of obstructions in a NLOS situation there tends to be a large amount of multipath. Obstructions like trees add to multipath and add attenuation to the overall Path Loss of the microwave link. Trees can be tricky because they are not constant due to movement caused by wind, foliage changes during various seasons, moisture content of the foliage, etc. Constant obstructions like buildings or hills are easier to model and predict.

General Overview of NLOS Wireless Technology

Current wireless backhaul technologies can help in NLOS cases. MIMO (Multiple Input Multiple Output) antenna signaling and spatial diversity reduces the amount of fade margin required. OFDM (Orthogonal Frequency Division Multiplexing) which divides the data into several parallel data streams helping the fading that occurs with multipath. Adaptive rate modulation also helps by giving the wireless backhaul radio the ability to manage the modulation scheme and bandwidth according to the RSL (receive signal level) optimizing the microwave communication link. Outdoor wireless bridges that can take advantage of these wireless backhaul technologies are the unlicensed wireless systems. Unlicensed wireless backhaul using these technologies can provide up to 300Mbps aggregate throughput (depending again on the characteristics of the microwave link path).

A common question of why a licensed microwave link, which can provide higher, full duplex connectivity, doesn't use OFDM wireless or MIMO antenna solutions and why they can't be used in NLOS (non line of sight) applications. In a NLOS wireless link application point to point wireless Ethernet bridge radios that use OFDM or MIMO take advantage of multipath for their connectivity. Because a licensed microwave link is not to inject any interference on other licensed microwave backhaul operators in the area they must have LOS (line of sight) and not cause heavy multipath. If a licensed microwave radio was to cause a lot of wireless multipath it could potentially reflect into another existing licensed microwave communication radio belonging to another party.

Prior to considering a NLOS wireless backhaul, a wireless site survey and a proper wireless path calculation should be performed. Field test may need to be performed in order to verify if a NLOS microwave link will work or to gather accurate estimates on throughput performance. As with any point to point wireless backhaul, a certified expert should perform the wireless installation.

Tags: Point to Point Wireless, Licensed wireless, General, Un-lincesed Wireless, Wireless 101

Wireless Interference - The Effect on Unlicensed Wireless Backhaul

Posted by Joe Wargo on Fri, Apr 16, 2010 @ 06:06 PM

When evaluating wireless backhaul technology, whether point to point wireless, point to multipoint wireless, or wireless mesh, the possibility of radio frequency interference disrupting a wireless link poses a concern. Interference can degrade a radio system's performance and in some cases even prevent the system from functioning at all.

For the purpose of this article "Wireless Interference" is defined as a wireless signal that alters, modifies, or disrupts the desired wireless signal as it travels from the transmitting source antenna to the receiving antenna.

Typical wireless interference is a result caused by the introduction of two or more radio waves being received into the receiving antenna from unwanted radio frequency (RF) signals disrupting the system's communication. Typically these signals are at or near the same frequency as the receive frequency of an established wireless backhaul system. The source of interference is usually from other transmitters operating very close in frequency to the impacted system or caused by "multipath" which is a result of a wireless signal reaching the receiving antenna from two or more paths.

Wireless interference can cause fading or noise on the receiving wireless antenna lowering the quality of signal. Noise is often measured by SNR ("signal to noise ratio") or a relationship of the desired signal quality to the level of undesired or corrupting signal (background noise). This can make it difficult for a wireless system to clearly understand the signal (communications) from the desired transmitting wireless radio. Interference can come into the receiving antenna either in or out of phase. The wireless backhaul system has to differentiate from the signal it should be receiving from its partnered outdoor wireless bridge from the wireless signal it is hearing from the wireless interference source.

This can be thought of in terms much like that of listening to music. Even if the music you are trying to listen to is at a desired volume but there is a lot of background noise, it can be difficult to listen to the music. The background noise can drown out the signal of the desired source causing missed bits of information. In an outdoor wireless backhaul system we see this as errors caused by dropped packets and/or multiple resends having to occur. A wireless link will have a certain threshold of wireless interference it can overcome before experiencing issues. This is often referred to a wireless system's CIR or carrier to interference ratio.

For a wireless backhaul system to operate properly it must maintain a quality receive signal level ("RSL"). Wireless bridges are designed to operate with a certain level of "Fade Margin" that allows the system to operate at a predictable reliability (for most point to point wireless systems 20 to 25dB of Fade Margin is recommended, but many point to multipoint wireless and wireless mesh systems can meet the manufactures requirements at a lower amount of Fade Margin). This means if a system has an RSL of -50dBm and it has a receiver threshold of -72dBm, you'll have 22dB of Fade Margin or the amount of dB signal strength a system can lose before you will experience errors (referred to as BER - Bite Error Ratio) or loss of connectivity.

Even if a wireless backhaul radio receiver has a good RSL the quality of the signal can be distorted by interference. A wireless bridge must have enough Fade Margin to overcome the interfering signal or have good enough CIR to function properly.

Wireless interference in regards to outdoor wireless backhaul often occurs with unlicensed wireless bridges ("license-exempt") operating in the 902-928MHz (spread spectrum), 2.4GHz, 5.3GHz, 5.4GHz, and 5.8GHz frequency bands. Note: 60GHz millimeter wave, often used in gigabit wireless backhaul, is unlicensed but is extremely immune to interference due to its inherent features of narrow beam widths and the occurrence of oxygen absorption over fairly short relative distance.

With unlicensed wireless bridges it can never be guaranteed that the wireless link will operate interference free and with any predictable reliability. Many manufactured wireless backhaul systems can help overcome interference by having a good carrier to interference ratio inherent with the hardware and by proper RF path design and wireless installation. Prior to deploying an outdoor unlicensed wireless backhaul a wireless spectrum analysis should be performed. A wireless installation company should use a proper Spectrum Analyzer to evaluate the amount of potential interfering signals in the desired frequency that is to be used (e.g. if you are deploying a 5.8GHz wireless backhaul system, as defined by the U-NII radio band of 5.725 to 5.825GHz, you would want to capture the amount of potential interference and the source of any particular wireless interference on any given channel in the 5.8GHz spectrum that will be used). A spectrum analysis will only show the amount of potential interference on the date it was taken. Other unlicensed wireless systems may be deployed at a later date that can introduce newer wireless interference.

Wireless Spectrum Analysis

Safe guards to help avoid or overcome unwanted wireless interference can be taken by choosing the appropriate wireless backhaul hardware. Using directional antennas can narrow the wireless signal's beam width, which in turn also narrows the amount listening area, while providing overall higher system gain. Using different polarizations (e.g. vertical vs. horizontal). Many of today's wireless radio systems have the ability to utilize iDFS (intelligent Dynamic Frequency Selection) that allows the wireless radio system to optimize by choosing the best wireless backhaul channel to operate on. Newer wireless bridge systems can also take advantage of using OFDM and MIMO that can help overcome interference.

Best practices should always be used by consulting an experienced outdoor wireless integrator who can perform proper spectrum analysis, path engineering and path calculations, consult on which manufacturer's equipment would be best for the solution, and perform proper wireless installation.


Tags: General, Un-lincesed Wireless, Wireless 101

Going Green with Solar Powered Wireless Backhaul

Posted by Joe Wargo on Mon, Apr 12, 2010 @ 05:04 PM

Wireless as a Green Technology? Actually it is based on power consumption and impact on the environment. Green technologies are the talk of the town as the world community tries to preserve our planet's natural resources by turning to cheaper and more efficient energy sources. Data and telecommunications are one of the fastest growing industries worldwide. How often do people think about the environmental impact of the broadband infrastructure rapidly being deployed?

For years the USA has relied on fiber infrastructure to provide its broadband backhaul. Fiber deployments require installing fiber cable either by aerial means (strung from pole to pole along a particular route) or by trenching the ground to put fiber in underground conduits. Both impact the environment. Aerial fiber requires a lot of PVC and rubber based jacketing to protect the fiber. These materials are not good for the environment. Aerial fiber also requires poles, either metal or wood, to be placed every 100ft or so. Underground fiber is put into conduits which eventual have a soil impact. Plus the trenching of natural land impacts nature. One must also take into account CO2 emissions that are produced in the construction and deployment of fiber.

Wireless backhaul, such as a point to point wireless Ethernet bridge, can provide data connectivity over 50+ miles. A single communications tower can be a hub site for many fixed wireless backhaul antennas. Existing buildings offer rooftop space that can be used so no new mounting infrastructure needs to be constructed.
Today many point to point wireless Ethernet bridge systems operate at 20W to 35W (-48vDC). Most point to multipoint wireless Ethernet bridge systems can run on POE (802.3af) or POE+ (802.3at). These systems have such a low power draw they can easily be powered by solar or wind generation.

Solar Power Wireless Backhaul   Wireless Solar Repeater

Take for example a solar powered repeater site used for a client's video backhaul. On a hill above a reservoir, where there was no local power available, two solar panels provide enough energy to power a point to multipoint wireless system that backhauls multiple PTZ IP cameras located a mile away and a point to point wireless Ethernet bridge to a remote facility 4 miles away. The outdoor wireless system is powered by recyclable batteries that are charges during the day by the solar panels. The systems provides up to 5 days of survivability in the event of the solar system failing.

Solar Proxim Wireless backhaul

Wireless backhaul radios use extremely little power and do not require any indoor facilities to house equipment. Using other technologies, like standard cable or fiber backhaul requires indoor switching equipment that consumes AC power and needs to be environmentally controlled by using power consuming air conditioning units. To cover vast distances using traditional backhaul requires multiple switching locations, like at a telco's Central Office, which are high power consuming facilities. Several wireless backhaul links can cover hundreds of miles with a total power consumption of just a few Watts of DC current using less than a few AMPS. Many home appliances use more power.

Installing a solar powered wireless backhaul system is relatively inexpensive, compared to running AC circuits. A quick ROI can be achieved from the savings of equipment shelter leasing costs and monthly power costs. Plus you'll be doing your part to help the environment!

Tags: Point to Point Wireless, Un-lincesed Wireless, Point to Multipoint, wireless video

Wireless Mesh - Unlicensed Wireless Ethernet Bridge

Posted by Joe Wargo on Sat, Apr 10, 2010 @ 03:44 PM

Wireless mesh networks, as a wireless backhaul technology, provide scalability, redundancy and reliability. Fixed wireless mesh can be deployed on existing infrastructure, such as: buildings, traffic signals, and light poles, saving a lot of capital expenditures on the costs of mounting structures. Most outdoor wireless bridge radios that support wireless mesh networking operate in unlicensed wireless bands of 2.4GHz, 5.3GHz, 5.4GHz, 5.8GHz, or the 4.9GHz Public Safety band. There are several really good manufactures of wireless mesh equipment (Firetide, Proxim Wireless, FluidMesh, Azalea Networks, etc.).

In a wireless mesh network, outdoor wireless bridge links are made up of a wireless mesh node that can send and receive wireless backhaul IP traffic. Wireless mesh nodes can function as a router, wireless access point, or a wireless gateway device. Through the relaying process, a packet of wireless data will find its way to its destination, passing through intermediate links providing reliable wireless backhaul communication. If one mesh node can no longer operate, the other mesh nodes can still communicate with each other, directly or through one or more intermediate links. Wireless mesh nodes can communicate with one or more nodes and can determine the best wireless backhaul path to transmit its traffic or perform load balancing on the network.

wireless mesh outdoor wireless bridge

Wireless mesh networks can be configured in a star topology or be made up of multiple types of configuration topologies such as: point to multipoint wireless backhaul or as a point to point wireless Ethernet bridge. Wireless mesh radios provide the ultimate flexibility from a single device.

Wireless mesh radio platforms have become a popular wireless Ethernet bridge architecture. Wireless mesh first became prevalent in the push for Municipal Wi-Fi applications by the wireless mesh manufactures and by Municipal governments trying to get notarized by offering wireless internet access to their communities. Municipal Wi-Fi was driven mostly by local politicians trying to boost their political clout with very little understanding on the actual outdoor wireless bridge technology. Many of these projects failed because of the lack of having a good business model to offer wireless internet access and in most cases little or no RF engineering was performed (wireless site survey, spectrum analysis, wireless network design, etc.). Making matters worse many manufactures were guilty of over marketing the capabilities of their products (how many wireless mesh nodes that could be deployed before having to have a backhaul to avoid high latency and maintain adequate throughput on the networks) and by not educating their clients on the of potential wireless interference when using unlicensed wireless backhaul.

Many municipal agencies consulted their hardware manufacture, which understand their equipment, but do not have actual experience in deploying outdoor wireless Ethernet bridges, nor should they. They are manufactures not wireless installation services companies. As many Municipal agencies soon found out that the cost was more than anticipated as they were told that to solve any connectivity issues they needed to just add more devices.

The wireless mesh hardware platform was not the issue. The problem was the lack of proper RF planning (performing proper wireless site survey and spectrum analysis), wireless network design, and proper wireless installation. Wireless mesh is a good topology but as with any outdoor wireless backhaul it needs to be done by experienced wireless integrators.

Recently, fixed wireless mesh has found a new niche market to serve. The growth of outdoor IP video surveillance has made wireless mesh a cost effective solution. Mesh, as an outdoor wireless bridge technology, provides the ultimate scalability and flexibility in network design. Wireless video networks can be scaled over time and wireless backhaul using mesh can allow cameras to be placed almost anywhere. Manufactures like Firetide, Proxim, and Fluidmesh were early adopters by optimizing their wireless mesh platform for video backhaul and have done a good job marketing to the IP video marketplace.

Tags: General, Un-lincesed Wireless, Wireless Industry, wireless video, wireless mesh

Point to Multipoint Wireless Ethernet Bridge

Posted by Joe Wargo on Sat, Apr 03, 2010 @ 04:21 PM

Outdoor point to multipoint wireless Ethernet bridge systems are flexible, economical, and easily deployed wireless backhaul solutions for connecting multiple remote sites to a network. Point to multipoint wireless backhaul is an ideal wireless last mile solution for interconnecting campus buildings, remote facilities, security systems, access control systems, IP video surveillance cameras, SCADA PLC's, or WISP applications as a DSL replacement. Point to multipoint wireless can also be used to backhaul wireless mesh networks. Theycan also be used to eliminate telco dependancy or to provide wireless network redundancy.

point to multipoint wirelessPoint to multipoint wireless Ethernet bridge systems are made up of a Base Station Unit (BSU or AP) that can communicate with multiple Subscriber Units (SU's). Many systems can handle over 100 plus SU's per BSU. In most cases the BSU's provide a sector antenna beam pattern (typical is 60 degree, with some systems allowing external antenna configurations for expanding to 90 and 120 degree sector antennas). Multiple BSU's can be installed to create a 360 degree sector (like a typical cell site configuration). 

Point to multipoint wireless Ethernet bridge systems can operate in the unlicensed wireless spectrum (900MHz, 2.4Ghz, 5.3GHz, 5.4GHz, or 5.8GHz), the 3.65GHz WiMax spectrum,  or in the 4.9GHz public safety band. There are propriatery point to multipoint wireless backhaul systems operated by various telecommunication providers that operate in the lincensed microwave wireless spectrums.

Point to multipoint wireless backhauls is generally used where bandwidth requirements are generally low, such as a DSL or T1 repalcement. Recently though  many point to multipoint wireless systems have taken advantage of the Wi-Fi 802.11n chip sets and can now provide wireless bandwidth up to 300Mbps aggregate throughput. Note: the actual throughput at any given SU is determined by the number of SU's connected in the system and the network configuration.

Some of the better point to multipoint wireless systems use OFDM (Orthogonal Frequency Division Multiplexing) to provide better near and non line of sight ("NLOS") connectivity. The newer 802.11n chip set systems also take advantage of multipathing by incorporating MIMO (2x2 or 3x3) to give even better NLOS capability and higher bandwidth. The range of a point to multipoint wireless backhaul can extend as far as 10 miles with clear line of sight ("LOS"), by using high gain directional antennas connected to the SU's. The optimum performance though of most point to multipoint wireless is in the 1 to 2 mile max range. NLOS applications need to be closer to the BSU / AP in order to have adequate system gain. 

There are a lot of manufactures that offer point to multipoint wireless Ethernet bridges. Some manufactures have been in the point to multipoint wireless arena for many years. Proxim with their Tsunami MP.11 series (5054-R which is a tri-band 5.3GHz, 5.4GHz, or 5.8GHz system, MP.16  that is a 3.3GHz, 3.5GHz, or 3.65GHz licensed WiMax system, and their newer high bandwidth MP8100 series), Motorola with their Canopy wireless (their newest is their Canopy 400 series that operates in the 5.4Ghz and the PtMP320 WiMax), and others such as: Alvarion, Firetide, Trango, Solectek and BelAir. Some of the newer players include FluidMesh (which specializes in wireless video backhaul and wireless mesh), Ubiquiti,and InscapeData.

When designing a point to multipoint wireless Ethernet bridge system it is highly recommended to perform a wireless site survey and a spectrum analysis. All systems regardless of how good they are have their limitations. The biggest source of failure we come across is unrealistic expectations of performance. Any organization thinking of deploying a point to multipoint wireless system should consult a professional wireless integration company that has a lot of experience designing and performing outdoor wireless installation

Tags: Licensed wireless, General, Un-lincesed Wireless, Wireless Industry, wireless video, Wireless 101

Point to Point Wireless Ethernet Bridge

Posted by Joe Wargo on Wed, Mar 31, 2010 @ 02:30 PM

Point to point wireless Ethernet bridges, also known as fixed wireless backhaul, are becoming extremely popular among organizations across all vertical markets. Once used only by the large telecommunication companies, wireless Ethernet bridges are being implemented by everyone, from federal, state, county, and local governments, utilities, health care organizations, agricultural industries, and even the private commercial sectors. 

Bridgewave Proxim wireless Ethernet bridge Wireless backhaul is an ideal complement or complete replacement to leased lines and fiber. Whether the requirement is to link the data and voice networks between individual buildings or link networks across large distances, organizations are increasingly turning to point to point wireless networks, both licensed microwave links and unlicensed wireless backhaul, as the preferred solution. Point to point wireless backhaul provides several advantages over leased lines:

  • Increased Bandwidth - With all the applications that are now driven across the network, IT departments are requiring more bandwidth across their network infrastructure. An outdoor wireless Ethernet bridge can provide true Ethernet throughput up to GigE Full Duplex (using gigabit wireless links).
  • Lower cost of installation and no recurring costs - Probably the number one driver for turning to outdoor wireless backhaul is the tremendous ROI point to point wireless bridges provide. On a 100Mbps Full Duplex wireless backhaul link the typical ROI is about 3 months. This is compared to a leased  DS3 at 45Mbps. So you can get over double the throughput and eliminate any reoccuring operational costs almost immediately. The wireless cost reduction savings can be even greater when compared o the cost of installing fiber networks.
  • Last mile connections - In many cases, organizations such as government or utilities who maintain multiple sites, just can't get their required bandwidth out to remote locations. Sometimes the best a local telco can provide is a T1. Point to point wireless can reach up to 50+ miles (if designed and installed properly). Where once you could only get a T1 circuit, you can now get 100Mbps Full Duplex up to GigE  (gigabit wireless) throughput, better known as wireless last mile.
  • Quick installation- A typical point to point wireless backhaul can be installed in a couple days. I always recommend using industry professionals that have a lot of experience (see my article "Wireless Installtion Done Properly").We've talked to a lot of clients that have waited over 6 months to have their telco provision a simple circuit. This is especially true when compared to fiber installations that can takes years to gain right away access and time it takes to trench conduit paths.
  • Reliability - Wireless backhauls designed and installed properly can provide 99.999% predictable reliability (see my article "Is Wireless Reliable"). Most telco's only provide a SLA of 99.9% uptime. In many cases where a client has installed wireless backhaul, like licensed microwave or millimeter wave gigabit wireless, for fiber redundancy we have seen the client actually convert over to using the wireless point to point backhaul as their primary and down grade their fiber connection as their redundancy. This is because the wireless backhaul typically provides a more direct path (less routing in the case of leased circuits) and is cheaper to maintain.

Point to point wireless Ethernet bridges can be used by any organization that has more than one facility that they need to connect to. There is a multitude of products in the market, both licensed microwave links and unlicensed wireless Ethernet bridges, that can solve many connectivity issues. Th price of wireless backhaul has come way down in price and is more affordable than ever. The quality of outdoor wireless backhaul is better than most other methods of connectivity.

The main reason more organizations haven't turned to outdoor wireless backhaul is either it is just not feasible do to their locations or a lack of education on what can be done with today's technology. The first step is to get a Feasibility Study by a qualified outdoor wireless vendor. A good wireless integrator can outline the best solution and the cost benefits.

Tags: Licensed wireless, General, Un-lincesed Wireless, Wireless Industry, Wireless 101

Outdoor Wireless Installation Done Properly

Posted by Joe Wargo on Sun, Mar 28, 2010 @ 04:39 PM

Proper outdoor wireless installation is the most important element of a wireless backhaul system. Over the past decade I have troubleshot hundred's of wireless backhaul networks and 95% of the issues I have seen are due to improper wireless installation.

Many would argue that choosing the right outdoor wireless bridge equipment is the most important. I would agree that there are both good and bad outdoor wireless backhaul equipment on the market, but for the most part the majority of wireless backhaul manufactures build pretty reliable radio hardware. The biggest difference comes between Carrier/Enterprise grade (higher end, low latency, microwave equipment that typically have a 20+ year shelf life) and Value Line equipment (typically under $5K and using 802.11b/g/a/n chip sets). 

Others would say that proper wireless network design and choosing the right technology, e.g. licensed microwave links or unlicensed wireless backhaul systems, is the most important. There are pluses and minuses with both systems, such as: potential wireless interference on unlicensed wireless backhaul systems or the need for clear line-of-sight with a licensed microwave link. Both systems if installed properly can provide reliable networks. Proper wireless engineering will produce the optimum  wireless network design using the appropriate equipment.

Even with the best wireless network design and best outdoor wireless backhaul equipment on the market, improper wireless installation will prevent a wireless backhual network from truly working to its potential. Many times we hear clients say the system worked fine when it was first installed but it has degraded over time. This can be caused by many issue. There was no interference when the system was first installed. Trees or other obstructions are now in the path, either creating a complete Fresnel Zone blockage or partial encroachment on the first Fresnel Zone. Antennas could have come out of alignment. Cabling and connectors could be weathered or damaged. The list goes on. Just like a race car, it must be built properly and maintenanced to work optimally. 

Many outdoor wireless bridge systems we troubleshoot lack proper materials for cabling, mounting, and weather proofing. Over time these systems get effected by the weather and slowly degrade. Systems that are not weather proofed correctly can get damaged over time by water getting into the connections or cabling. Improper mounting can cause antenna systems to come out of alignment. Systems installed with out the proper amount of fade margin can also have periodic issues with weather (see my article "Does Weather Effect Wireless").

Wireless backhaul, whether you are talking about wireless mesh, WiMax, point to multipont wireless, or point to point wireless backhaul, systems can function with extreme reliability and predictability if installed correctly. The mobile wireless carriers take this matter critically and waste no expenses on ensuring their systems are installed properly. Any down time can cost them tens of thousands of dollars. The craziest thing we see is organizations that are willing to rely on wireless technology for their primary connectivity but pinch pennies by choosing the cheapest and many times least experienced installation companies. Worst is when a manufacture convinces and end user with little to no experience installing an outdoor wireless bridge that they can do it themselves.


Wireless Installation Tower climber


The best wireless installers are those that have a lot of tower installation experience. They typically install systems to last for many years. They also don't want to lose revenue having to come back and climb a tower again to repair a bad installation. Even though many of the outdoor wireless systems seem straight forward or easy to install based on the manufactures operation manual, the fact remains that outdoor wireless installation is a skilled trade and best performed by professionals with years of experience. You can change the oil in your high end sports car but that doesn't mean you should!


Tags: Licensed wireless, General, Un-lincesed Wireless, Wireless Industry, Wireless 101