Alpha Omega Wireless Blog

Point to Point Wireless Bridge Through a Glass Window

Posted by Joe Wargo on Thu, Mar 14, 2013 @ 03:37 PM

When we think of wireless backhaul and microwave communications we typically think of a point to point wireless bridge that is from communication tower to another tower or building rooftop to another building rooftop. In most all cases for wireless point to point microwave backhaul to work there needs to be line of sight (“LOS”) from one antenna to the other. Some other important factors for a point to point wireless bridge to function correctly is to have proper Fresnel Zone clearance and calculated system gain.

In order to make sure a wireless point to point link, whether you are talking about a licensed microwave backhaul or a 5GHz unlicensed point to point wireless Ethernet bridge, will function properly and have predictable reliability a proper wireless network design and path calculation needs to be performed. By performing a quality (radio frequency) RF path calculation we can determine the Free Space Path Loss and overall wireless system gain based on a particular wireless radio system’s receiver sensitivity threshold. This helps determine frequencies that can be used, output power, RSL (received signal level), polarizations, antenna sizes, and antenna heights. The other factor in designing a point to point wireless bridge is to take into account the signal to noise ratio (the incoming signal quality level over any external frequency noise / interference).

With a typical outdoor point to point wireless link it is easy for a wireless installation company to perform all the necessary path calculations and engineering to design a wireless point to point link with 99.999% predictable reliability (<5min of predictable outage a year). But what happens if you don’t have roof rights access to do a wireless installation on the building’s roof or there is no way to cable from the network room / IDF to the roof? Yet from the building’s window you can look out and see the other end clear as day with good LOS. This happens in the enterprise world where a company may occupy a certain floor of a high rise but can’t get roof right access either because of physical challenges or lease contract issues. Why not just put the antenna behind one of the windows?

Shooting a point to point wireless backhaul through glass is not as easy as it may seem. Wireless bridges are in essence sound waves that operate in frequencies that humans can’t obviously hear. Most all glass used in building construction have some sort of sound attenuation (whether just buy the materials in the glass or on purpose to block out outside sound). In the past most glass windows had lead or other metallic compounds in them. Newer windows use a special sound attenuation film to make the inside more quite. Sometimes this glass also uses special films for polarization to block sun glare.  This attenuation causes the signal quality of the point to point wireless system to be degraded in the form of signal loss.

Wireless through glass

Windows can also have a reflective property that can cause the wireless bridge to bounce the TX (transmit) signal back into itself causing self-interference and distortion on the radio system. When this happens we see a lot of errors on the network as BER (Bit Error Ratio), Jitter, and CRC errors. This can also over time damage the wireless point to point radio end.

So can it be done? Yes! Over the years we have successfully done wireless installations from behind glass and recently did a critical point to point wireless backhaul at SXSW for a major video streaming event. How did we do it? First we took into account all the possible issues as mentioned above. The first step was to calculate the link budget by doing a detailed path calculation by building in the possible loss due to the attenuation of the glass. Because the link had to be installed using an unlicensed wireless Ethernet bridge we decided to use a MIMO (dual polarization radio that uses both vertical and horizontal polarized TX/RX signals).  In the recent case the shot was very short (less than one mile) and the environmental noise in 5.8GHz was extremely high. We decided to use 5.3GHz band that operates in DFS (dynamic frequency selection – basically channel hopper) in the USA.  Then comes the fun part of the installation. We had to play with the polarizations of each end’s antennas, adjust the power output levels on each side separately, and move the radio end behind the glass back and forth from the glass to find the optimum distance of the antenna from the glass.

Wireless Glass Shot

There are other radio specific settings that can be applied to help the radio from getting false radar detection (which is a requirement of the FCC that causes the radio to jump channels and lock out various frequencies if it sees a DFS channel signal from another source. This happens when the glass reflects its own signal back into itself out of phase. The system needs to be adjusted so that it doesn’t think its own signal is from another outside source. If the 5.8GHz bad was clean of outside interference you still need to adjust so that the radio doesn’t take on errors.

At the end of the day putting one end of the wireless point to point system behind glass allowed over 100Mbps of bandwidth to be used for the event. Time and material costs were saved by not having to run fiber (due to the length of the cable run to the nearest IDF (network closet) to the roof along with power. It is not racommended to shoot point to point wireless through a glass window and it is always Best Practice to go from rooftop to rooftop, but sometimes its the only option. It takes a lot of planning and back and forth testing, but if the wireless installation is done properly shooting wireless backhaul through glass can work!

Tags: Alpha Omega Wireless, Point to Point Wireless, General, Un-lincesed Wireless, AO Wireless, Wireless 101

Wireless Backhaul Used All Over SXSW

Posted by Joe Wargo on Sat, Mar 09, 2013 @ 06:06 PM

Wireless backhaul is used all over Austin during the SXSW event. In order to get Internet connectivity to major events and venues wireless bridges, in forms of point to point wireless bridge and point to multipoint wireless bridge technologies are used. At the events and venues Wi-Fi is also deployed to help provide wireless communications to enhance the user experience.

Wireless Repeater SXSW

At the SXSW 2013 (South by Southwest) Film and Music Festival tens of thousands of people from around the world swarm to Austin, TX to experience the latest in film, technology, gaming, and see the over 2000 bands that playing live at over 200 venues. The SXSW event merges film, music, and technology all in one place. Technology and social media are playing an even larger role at SXSW. Major technology, social media, and corporate giants like, Dell, Samsung, Google, Microsoft, AT&T, Yahoo, and others all have a presence and host amazing parties and events at SXSW.

In years past, one of the biggest complaints was the lack of broadband connectivity, that's if you could get connected at all. With so many people in such a concentrated area many of the cellular networks get overloaded and come to a crawl. Add to the fact that there is now a 2 to 1 ratio of Wi-Fi enabled devices to people. Laptops, iPhones, iPads, and all the other smartphone devices were present everywhere. This year SXSW wants to make sure that they can enhance the attendees experience by bringing wireless bandwidth to the people. Plus all the major event hosts are using a large amount of wireless bandwidth for production and exhibit displays.

The wireless communication at SXSW is being done by deploying a GigE microwave backhaul from a major local telecommunication provider to the roof of a hotel close to all the action. That location acts as a wireless repeater. Multiple point to point wireless bridge links are used from the wireless repeater location to provide wireless connections from 400Mbps full duplex wireless connectivity to 100Mbps wireless bridges.

Also from the same roof top that the wireless point to point links are initiated, point to multipoint wireless systems are used to provide multiple wireless connections. The point to multipoint wireless bridge end nodes receive anywhere from 10Mbps up to 100Mbps of wireless bandwidth.

In order to pull off having so much wireless frequency all over town coming from the wireless repeater site, multiple radio frequencies are used during the wireless network design and wireless installation. One of the largest challenges is the fact that during SXSW there is a lot of wireless interference caused by so many people deploying outdoor wireless, to include outdoor Wi-Fi.  Plus, since SXSW is a temporary event, the use of licensed microwave is not feasible and unlicensed wireless has to be used. Frequencies ranging from millimeter-wave (60GHz), unlicensed 24GHz point to point microwave, and unlicensed 5.3GHz and 5.8GHz wireless radios are used.

For the Wi-Fi at some of the events, wireless Wi-Fi arrays are used to deploy high density wireless communications (see “AO Wireless Deploys Xirrus Arrays at SXSW for High-Density Wireless”). SXSW doesn’t provide Wi-Fi at all the events but at some of the major ones they do in order to make sure the end user experience is enhanced. There is just too many venues to put Wi-Fi at all of them.

By using wireless backhaul, both point to point wireless bridges and point to multipoint wireless Ethernet bridges, wireless connectivity is deployed to venues and events that can be in buildings or out in the middle of a field or parking lot. Broadband is made available for production, point of sale systems, ticketing systems, exhibit interaction, and most of all an enhanced attendee experience.

Wireless backhaul used for the core network distribution and last mile wireless used to provide bandwidth to special event venues gives SXSW a lot of flexibility and the ability to provide Wi-Fi to attendees. Once the event is over the equipment will be removed as if it was never there.

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

High Density Wi-Fi at SXSW

Posted by Joe Wargo on Fri, Mar 30, 2012 @ 12:14 PM

Wireless connectivity and wireless mobility has become a way of life. Today most everyone is carrying a mobile device and expects to have high speed wireless bandwidth everywhere they go. In many cases, people now have more than one wireless device carrying around their smart phone and their tablet device (e.g. iPad). A major problem in the wireless industry is when wireless networks get overloaded due to the high density of users on a local network. This problem becomes even greater when you have events that have thousands of people all trying to get online with their wireless devices all at the same time. Cellular networks can get slammed. This is why many carriers try and off load people onto Wi-Fi hotspots in order to free up the demand for their 3G / 4G networks.

A rule of thumb is to have a max capacity of 40 active Wi-Fi users on an access point at any given time. Now many manufactures have pushed that limit by using various techniques like timing algorithms, but as a general rule for high performance 40 is a good number. In high density wireless applications the thing to remember is that even if everyone is not trying to use their wireless handheld device, the devices still beacon the network. This causes a lot of traffic and overhead to an access point.

So what happens when you put thousands of people in a small area all trying to get a wireless Ethernet bridge using Wi-Fi connectivity? If you do the math you would have to add a lot of wireless access points in an area to handle the load. With Wi-Fi 802.11b/g 2.4GHz there are only three non-overlapping channels. In Wi-Fi 802.11a there are 8+ depending on the channel widths. Most all devices will try and use the 2.4GHz 802.11b/g Wi-Fi first by default. With only three non overlapping channels it becomes difficult to put a lot of AP’s next to each other in a small place, especially if the AP’s are using omni directional antennas. You have to do strict channel and power planning.

Recently, we were asked to provide Wi-Fi for over 3000 users in an area of 100ft x 500ft for an outdoor high profile event party for SXSW. We were able to not only provide Wi-Fi for that many users but where able to provide high speed seemly roaming without any problems. How did we do it?

First, we brought in a 300Mbps full duplex wireless backhaul to the event from a location across town using microwave communication. We didn’t have direct line of sight so we used a rooftop to create a wireless repeater. We did a point to point wireless shot from the main building to the wireless repeater and then another point to point wireless bridge down to the outdoor event. We used 24GHz SAF Tehnika Lumina radios for the microwave communication.

For the Wi-Fi at the event we choose to use a Wi-Fi array system by Xirrus. Xirrus arrays use multiple AP’s with sector antennas to distribute the Wi-Fi signals much like a cellular site design. This allows for greater output and better RF channel control. With the Xirrus system we were also able to force devices that had 802.11a 5GHz capability onto a 5GHz AP to free up the demand of the 802.11b/g 2,4GHz AP’s. Each Xirrus array has its own built in controller which communicates with every other array in the system. This was very effective and saved on costs of having to have an expensive traditional Wi-Fi controller on site. We weren’t able to cable each array directly so in some cases we used a millimeter wave solution to create a wireless Ethernet bridge between arrays.

Xirrus Array

The crowd loved it and it was amazing to be able to have wireless roaming capability on my iPad while Skyping my wife who couldn’t attend the event!

Tags: Alpha Omega Wireless, Point to Point Wireless, Un-lincesed Wireless, Wi-Fi

Wireless Backhaul is a Winner in Natural Disasters

Posted by Joe Wargo on Sat, Mar 12, 2011 @ 11:07 PM

As a Wireless Integrator, that has deployed thousands of wireless Ethernet bridges, I am a firm believer that wireless technology for broadband backhaul not only provides a phenomenal value but in many cases is a better technology for broadband backhaul than traditional fiber / copper infrastructure. Wireless backhaul, whether we are talking about point to point wireless backhaul, using licensed microwave or an unlicensed wireless Ethernet bridge, point to multipoint wireless Ethernet backhaul (using 5GHz unlicensed wireless band or WiMax), or wireless mesh,  can provide greater reliability, last mile presence, quicker deployments, and is far cheaper than hard line infrastructure.

You can say, “Well you do wireless backhaul for a living so you are biased.” Let me tell you about a recent trip I took to a third world country and experienced a natural disaster. Recently I was on the island of Roatan in Honduras while a hurricane passed over the island. We experience sustained winds of 70+mph (with gusts of 100mph) and about 4 inches of rain. During the storm I was uploading photos to Facebook because I had a fast, uninterrupted full 3G cellular services without any outage or latency.

Roatan Hurricain
Remember Katrina? Well most of all the fiber networks in New Orleans were wiped out and untill today it hasn't been all fully replaced. Immediately after the hurricain there wireless networks were installed all over to provide voice and data connectivity.

Island TowerAll throughout the Caribbean and Central America most countries have leapfrogged the USA in the use of wireless backhaul for telecommunications and broadband services. A lot of countries can’t run fiber due to terrain (jungles, mountains, waterways, and a lack of infrastructure) and the pure inability to afford a fiber build out. Wireless though is everywhere. You can be in the jungles of Belize and have a solid 3G connection.  

In order to get broadband connectivity and voice service many of the Caribbean islands depend on point to point microwave connectivity. Then cellular and point to multipoint wireless is used to distribute wireless broadband around the island. One would wonder how well the service coverage would be and the quality of the wireless installation would be in a third world country. After seeing first hand during a hurricane I would say it’s pretty good! Back home in the USA where I am served by a local cable provider my internet connection gets knocked out all the time when we have a storm of 30 to 40MPH winds

Wireless backhaul is far easier and cheaper to deploy than fiber. Broadband wireless networks also allow for a lot of flexibility in access to a POP (point of presence) and network design. The greatest concern most people have with using wireless backhaul is if it’s reliable. From what I experienced I would say it’s extremely reliable. Understand that microwave radio equipment uses extremely little power. In most cases a microwave radio can be powered on a battery or over solar. Most outdoor radio units use -48vDC at 30W. A standard UPS can keep a wireless end node powered for hours. If installed properly a wireless network can provide 99.999% reliability. See my previous articles: “Does Weather Effect Wireless? The 5 Misconceptions - Part 1” and “Is Wireless Reliable? - The 5 Misconceptions - Part 2.”

Like I always say, if wireless backhaul is properly engineered and the wireless installation is done properly it is extremely reliable!

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

Wireless Backhaul Makes Financial Sense

Posted by Joe Wargo on Fri, Sep 24, 2010 @ 05:06 PM

Wireless backhaul, often referred to as fixed wireless backhaul or wireless Ethernet bridges, has become a standard for creating network connectivity between locations. Wireless backhaul can be used for establishing data network connections from building to building, field locations to a network presence, connecting network fiber segments, or last mile connections, etc. Wireless Ethernet bridges can also be used for connecting devices on to networks, like IP video cameras, SCADA devices, client devices, phones, two-way radio / pagers, etc.

Wireless backhaul can be in the form of point to point wireless, point to multipoint wireless, or wireless mesh configurations. Wireless bridges can be licensed microwave links or unlicensed wireless Ethernet bridges. A licensed microwave link or wireless Ethernet bridge can provide throughput as low as 10Mbps up to GigE full duplex (with gigabit wireless).

Wireless Ethernet bridges, allow you to eliminate reoccurring costs of leasing fiber from telecommunication companies, eliminate the cost of additional head end equipment, and AES encryption hardware devices. Wireless Ethernet bridges preserve native IP throughout the system. Because you own the microwave link connection and not lease it, ROI is maximized with a low CPEX. You also gain the peace of mind of having control over your own infrastructure.

Take for example the cost to lease a DS3 (45Mbps) connection through a carrier. A typical scenario is that it costs roughly $4000.00 a month with a 3 to 5 year contract. Over three years that’s $144,000.00! Let’s not forget that it also typically takes 3 to 6 months to provision.

Now for comparison, let’s look at a point to point wireless Ethernet bridge using a licensed microwave radios. Although you can install a 50Mbps full duplex (100Mbps aggregate throughput) wireless bridge, most systems are typically purchased at 100Mbps full duplex (200Mbps aggregate throughput) because there just isn’t much cost differential between a 50Mbps and 100Mbps full duplex licensed microwave link. It’s typically the same radio system and just software throttled. Most licensed microwave radios are capable of 366Mbps full duplex (732Mbps aggregate throughput) and 60GHz and 80GHz millimeter wave is GigE full duplex.

A typical 100Mbps full duplex licensed microwave link, which can be installed in several days rather than 4 to 6 months like a DS3, would have a CAPEX of $20,000.00 to $30,000.00 depending on the frequency and distance. Say you add in a 5 year advanced replacement manufacture warranty and annual support from the integrator at a cost of $15,000.00. That’s roughly $45,000.00 compared to $144,000.00. That gives you an ROI of roughly 11 months. Plus you have over double the bandwidth!

Wireless ROI

As you compare higher bandwidths like leased 100Mbps or gigabit fiber the ROI is increased even further. Most GigE wireless backhauls have an ROI of 3 to 4 months. That’s it. No more reoccurring costs because you own it. If a wireless Ethernet bridge is properly engineered and the wireless installation is done by a professional wireless integrator a point to point wireless backhaul can provide greater security over leased lines and give 99.999% reliability (meaning <5min of predictable outage a year). Most telecommunication companies can only guaranty 99.9% on a SLA because they know they’ll have network outages throughout the year.

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

Wireless Backhaul Can Prevent Network Outages

Posted by Joe Wargo on Fri, Aug 27, 2010 @ 05:09 PM

Wireless backhaul in the form of point to point microwave - licensed microwave links or unlicensed wireless Ethernet bridges, point to multipoint wireless Ethernet bridges, or wireless mesh network infrastructures can provide up to 99.999% reliability and keep you up and running when your telecommunications provider fails you.

Redundant Wireless backhaul Do you ever experience downtime on you network due to outages with your telecommunications provider, such as: AT&T, Verizon, or Comcast? What does a network outage cost you organization in dollars and man hours due to lack of productivity and internal communication or with clients? What do you say? This never happens? Think again!

You think you’re safe because you have a point to point fiber connection from your telecommunications vendor? Read my article “Outdoor Wireless Bridges or Fiber, Which Do You Trust.” What if you use an MPLS network, doesn’t that provide you failover redundancy? What about having different carriers for a backup connection? Or what about using cellular modems as a last result? Aren’t you protected by having redundancy? Not really!

The true fact is that the major telecommunications companies have outages all the time. December 11th, 2009 San Francisco experienced a several hour AT&T outage. July 21, 2010, AT&T Wireless had a regional outage for hours in NC. On April 9th, 2009 Santa Clara County, CA declared a local emergency when someone intentionally cut an underground fiber optic cable in South San Jose taking out cellular, internet, and phone usage to AT&T, Verizon, and Sprint/Nextel customers. This affected multiple cities. A local hospital had to cancel surgeries due to the emergency. Recently, Union City, CA experienced a city wide outage when central office went dark. All voice, internet, MPLS, cellular, etc. was out for almost 10 hours.

So what happens when you have no cellular, internet, data, or voice connectivity?  For some organizations they have critical operations that have to be monitored so they have to be physically manned if the network goes down. What’s the cost to deploy people to remote sites or work overtime during the middle of the night? What about lost data? Some organizations can run into the millions of dollars an hour during a network outage.

Too often organizations fail to ensure their communications, both data and voice, are protected by not having appropriate redundancy or just flat out relying on a third party telecommunications vendor. Many times those who have a redundancy solution in place don’t have “True Redundancy.” Many overlook their WAN connections or have single point of failures in using the same medium (such as fiber), or taking the same external routes (out the same conduits from their MPOE), or have unknown points of failure by relying on third party telco providers’ networks. You can have MPLS but if you first connect through a local central office and that CO goes dark there is an issue. Even with backup power central office have gone dark (recently in Union City, CA) and fiber lines have been cut (San Jose, CA).

Licensed Microwave LinkWireless backhaul connectivity, both point to point wireless links and point to multipoint wireless bridges, provide an avenue for extremely reliable primary connections and for creating “True Redundant” network paths and connections. With both unlicensed wireless Ethernet bridges or licensed microwave links, an organization can create a completely separate stand alone network and eliminate the dependency on third parties equipment and facilities, and remove the risk of failure of fiber cuts off site and out of an organizations control.

So why own your own wireless backhaul network? Wireless backhaul, with proper wireless path engineering, the use of the right outdoor wireless backhaul equipment, and proper wireless installation can provide truly reliable networks. See articles, “Is Wireless Reliable? - The 5 Misconceptions - Part 2” and “Outdoor Wireless Installation Done Properly.”

Wireless backhaul can have multiple advantages. Wireless networks can be used for primary or redundant links. Throughput can match or even exceed that of a leased line from a telco. You can get connectivity where you can’t get it from a telco for last mile solutions. Wireless backhaul typically has an extremely low ROI and can eliminate reoccurring lease line costs. Wireless installation can be done in days compared to months of provisioning time from a telco. Also with wireless backhaul you have complete control of your network. Even in the event of equipment failure wireless nodes can be restored quickly by simply hot swapping the radio communications equipment.

That’s right no more trouble tickets from some call center agent in another country!

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

Wireless Backhaul Communication Towers are a Great Investment

Posted by Joe Wargo on Sat, Aug 21, 2010 @ 03:49 PM

Wireless backhaul, also known as fixed wireless, technology has become a standard means of creating a data communications link between locations. Microwave radio links can be used to make data connections from building to building, to connect remote field locations to a network presence (also known as last mile wireless), connecting network fiber segments, and for connecting network devices (like IP video cameras, SCADA devices, client devices, phones, two-way radio / pagers, etc.) to networks.

Wireless backhaul can be in point to point wireless, point to multipoint wireless, or wireless mesh configurations. Wireless bridges can be licensed microwave links or unlicensed wireless Ethernet bridges. A licensed microwave link or unlicensed wireless Ethernet bridge can provide throughput as low as 10Mbps up to GigE full duplex (with gigabit wireless). There are many wireless backhaul radio platforms offering a solution to just about any application. Wireless backhaul systems can provide 99.999% reliability. A Point to point wireless Ethernet bridge or licensed microwave link can enable high capacity wireless backhaul connections from less than one mile to more than 50 miles, without performance degradation. Licensed microwave links and unlicensed wireless Ethernet bridges enable carrier class delivery of IP services with full wire-speed performance. Typical latency on a wireless Ethernet bridge or licensed microwave link is under 1ms.

communication towerEven though there are some outdoor wireless radio systems that can do non-line-of-sight (“NLOS”), the majority of wireless backhaul requires line-of-sight (“LOS”) with proper Fresnel Zone clearance to properly operate. This means the transmitting and receiving antennas most be able to see one another with any obstructions. In most cases this requires mounting the antennas on a structure with adequate height to create LOS.

Many times when doing a point to point microwave link from one tall buildings roof top to another’s it can be easy to have LOS.
Sometimes this is not possible. Putting a antenna mast on a roof top can sometimes be sufficient. Other times it may become necessary to construct a communications tower. The first reactions that come to a client’s mind when a wireless installation vendor says a tower need to be built is no way. Several misconceptions arise. Towers are too expensive, unsightly, and are a huge construction project. Reality is that none of these are true.

Communication towers are relatively inexpensive to have installed. Leasing high speed bandwidth form a telco or installing dark fiber is extremely expensive. Point to point wireless backhaul or creating point to multipoint wireless Ethernet bridges for last mile connections have a rapid ROI (typically less than 6 months with no reoccurring costs). Adding a tower into the solutions may only add 3 to 4 months until the CAPEX achieves and ROI. Free standing towers from 40ft to 80ft in height can be installed from $15,000 to $35,000. That is not much money when you look at the big picture.

Build it and they will come! Communication towers are typically built for an initial solution but can offer great potential for future wireless backhaul projects. The tower may have been built to accommodate a point to point wireless bridge like a licensed microwave link between two locations. Now in place it may be used for other wireless Ethernet bridges or point to multipoint last mile wireless bridge connections. Odds are that if you needed to build a tower to gain some height in a geographical area other may need some height too. Leasing opportunities can come knocking on the door. Tower can create a great source of re-occurring revenue for an organization by leasing antenna space off to other parties that need a repeater location or leasing space to the mobile carriers, like At&t, Verizon, Sprint, Clearwire, etc. These opportunities can pay for the tower itself.

Roof top towerThe fact is that there are tower all around us and we just don’t even notice them. Microwave communication towers tend to blend into the skyline. So many times we hear about cosmetic concerns when it comes to mounting antennas on buildings but the fact remains that they are all around and no one ever notices them (unless you are in the wireless industry and pay attention to them). Many are less obtrusive that satellite TV dishes everyone mounts on their homes!

Microwave tower have been manufactured in ready to deploy configurations and even come with approved engineered design drawings making the permitting process simple. Communication towers used for wireless backhaul can typically be installed within a few days and offer a long term solid structure for mounting wireless backhaul antennas and equipment.

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

The Difference of Two Wireless Backhaul Paths

Posted by Joe Wargo on Mon, Jun 28, 2010 @ 05:49 PM

When considering doing a wireless installation of a point to point wireless Ethernet bridge, also known as fixed wireless backhaul, there are several options. Say you want to connect two buildings 4 miles apart and the path has good line of sight ("LOS") with proper Fresnel Zone clearance. Do you go with a licensed microwave link or an unlicensed wireless Ethernet bridge system?

The terms "unlicensed wireless bridge" and "licensed microwave link" refer to the radio frequency spectrum characteristics set by the U.S. Federal Communications Commission ("FCC") or equivalent national government regulatory body. Licensed products require regulatory approval before deployment while license-exempt products can be deployed without any regulatory approval.

Licensed microwave communication links offer true full duplex communications. Licensed microwave wireless systems are becoming more popular as a result of wireless interference in unlicensed wireless spectrum. Licensed microwave radios provide security from the risk of interference from other RF systems. In a licensed system the channels that the radio system transmits and receives on are owned by the user and are registered with the FCC for frequency coordination. Getting a license is inexpensive and can be obtained in the matter of weeks.

The most common wireless backhaul, known as a wireless Ethernet bridge, operate in the unlicensed wireless (license-exempt) 900MHz (902-928), 2.4GHz, 5.3GHz, 5.4GHz, 5.8GHz frequencies of the RF spectrum and are exempt from FCC licensing requirements. There are also 24GHz, and 60GHz wireless bridge point to point links that are considered unlicensed wireless, but are typically immune to interference. This means the system operator does not have to apply for and purchase a fixed microwave communication link license from the FCC. These systems, although quick to deploy, do not promise exclusive use of the band and are susceptible to potential interference.

Recently we had a client that was operating two wireless backhaul networks for roughly four years using two sets of Motorola PTP600 unlicensed wireless Ethernet bridges. When they were originally installed they were getting almost 300Mbps aggregate throughput (this is like having 150Mbps full duplex throughput). Over the years the wireless bridges started to get hit with interference. The PTP600 wireless backhaul radios do channel hop to try and operate on a cleaner frequency channel when they receive high levels of wireless interference. They also can down step their modulation to create a better RF communication, which also lowers the radios wireless throughput capacity. They ended up struggling with only about 30Mbps aggregate throughput due to the amount of wireless interference they were being hit with.

SAF Lumina InstallWe ended up replacing the Motorola PTP600 unlicensed 5.8GHz wireless Ethernet bridges with SAF Tehnika CFIP Lumina licensed point to point microwave links. The new wireless bridges operate in the licensed 18GHz frequency. The SAF Lumina licensed microwave links are now providing the client with 366Mbps Full Duplex (over 720Mbps aggregate) throughput. Because the SAF Lumina are licensed wireless and the frequencies are now owned by the client they are operating interference free. We were also able to downsize the antenna sizes to smaller parabolic dishes.

Unlicensed point to point wireless bridges became very popular because anyone could buy them and deploy them with little experience. Note: even unlicensed point to point wireless links should be installed by certified professionals, see my article "Outdoor Wireless Installation Done Properly". Licensed microwave communications can be daunting for those that don't understand it. Licensed microwave point to point wireless links provide far greater performance, security, and longevity. Today licensed microwave wireless bridges are about the same price as any carrier grade unlicensed point to point wireless Ethernet bridge. Licensed wireless links do need clear LOS where unlicensed wireless links can be used in nLOS applications.

If you have good LOS and want true fiber replacement on a primary network connectivity path licensed microwave links should be considered over unlicensed wireless bridges.

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

Understanding Microwave Communication Frequencies

Posted by Joe Wargo on Sun, Jun 27, 2010 @ 03:39 PM

The term "Microwave" is a broad term that covers the UHF (Ultra High Frequency with frequencies between 300MHz and 3GHz) to the EHF (Extremely High Frequency with frequencies between 30GHz to 300GHz). Licensed microwave links and unlicensed wireless Ethernet bridges typically operate in the SHF (Super High Frequency with frequencies between 3GHz to 30GHz) and the EHF bands.

Microwave Communication Tower

A general rule of thumb is that lower the frequency the farther the signal will travel. Also lower frequencies the lower the throughput and higher the frequency the higher the throughput. Again this is in general terms and depends on the wireless radio hardware used.

The terms "unlicensed wireless bridge" and "licensed microwave link" refer to the radio frequency spectrum characteristics set by the U.S. Federal Communications Commission ("FCC") or equivalent national government regulatory body. Licensed products require regulatory approval before deployment while license-exempt products can be deployed without any regulatory approval.

Licensed microwave link frequencies used for wireless backhaul in a point to point wireless backhaul operate 6GHz, 11GHz, 18GHz, 23GHz bands and the 80GHz millimeter wave E-band. Unlicensed wireless Ethernet bridges, used in point to point wireless bridges, point to multipoint wireless bridges, or wireless mesh configurations, typically operate in 900MHz, 2.4GHz, 5.3GHz, 5.4GHz, or 5.8GHz frequencies. There is also the 60GHz millimeter wave band that is used for point to point gigabit wireless bridges.

There are registered frequencies that many think are licensed but are actually unlicensed, like the 3.65GHz WiMax band used for point to multipoint wireless backhaul and the 4.9GHz Public Safety band. These registered bands do provide some protection against interference but only require local users to coordinate with one another on frequency channel coordination. This is often confused by Public Safety organizations that think the 4.9GHz band is for exclusive use by local law enforcement. Anyone can register the use of the 4.9GHz band as long as it's used for some form of public safety, such as video backhaul.

BridgeWave Proxim ResundancyLicensed microwave wireless radio systems are typically built and designed for long term solutions. Point to point licensed microwave links are true fiber replacement systems and offer full duplex wireless communications for both Ethernet and TDM. The licensed wireless bridge hardware is designed to provide carrier grade performance (high bandwidth and low latency). Because a microwave link is licensed and is not to inject and interference on other licensed microwave backhaul operators in the area they must have LOS (line of sight) and not cause heavy multipath. This is a common question of why licensed microwave radios don't use OFDM or MIMO and why they can't be used in NLOS (non line of sight) applications. In a NLOS wireless link application unlicensed wireless backhaul radios that use OFDM or MIMO take advantage of multipath for their connectivity.

Microwave communication using unlicensed wireless Ethernet bridge systems have been an extremely popular choice for outdoor wireless backhaul. 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. 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 new 802.11n based wireless backhaul radios use OFDM and MIMO taking advantage of multipath, especially helpful in NLOS (non line of sight) applications. The major issue with unlicensed wireless Ethernet bridges is potential wireless interference.

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

Understanding Fixed Wireless Backhaul Configurations

Posted by Joe Wargo on Wed, Jun 23, 2010 @ 03:14 PM

Wireless backhaul, also known as fixed wireless bridges, has become a standard means of creating a microwave communication between locations; whether building to building, last mile wireless to connect remote locations to a network presence, or for connecting devices like IP video cameras, access control, SCADA devices, client devices, or phones to networks. Wireless backhaul can be deployed in several network configurations.

Fixed Wireless RepeaterA point to point wireless bridge is when only two microwave radio ends are bridged together to create a single wireless network path. Point to point wireless links are an ideal complement or replacement to leased lines and fiber. A point to point microwave link is used to create a wireless bridge network between two buildings to connect LAN connectivity or for creating a microwave link between two towers to join two WAN network segments together across large distances. Point to point wireless bridges can be licensed microwave links or unlicensed wireless Ethernet bridges and can provide throughput as low as 10Mbps up to GigE full duplex (with gigabit wireless).

Licensed microwave links used for point to point wireless backhaul operate in the 6GHz, 11GHz, 18GHz, and 23GHz frequencies and provide true full duplex wireless Ethernet and TDM communications. Licensed microwave links can provide up to 366Mbps full duplex or 732Mbps aggregate throughput using a single radio unit. Dual radio units can be combined on a single antenna to provide double the bandwidth and complete failover redundancy.

A few exceptions are the 24GHz microwave links that are unlicensed but work just like the licensed 23GHz microwave links and provide the full duplex connectivity and the 60GHz millimeter wave systems that provide up to full duplex gigabit wireless backhaul. There is also the 80GHz millimeter wave E-band that is a registered frequency that is used to provide gigabit wireless links. Unlicensed point to point wireless Ethernet bridges typically communicate in TDD because they use the same frequency channel to talk and listen. They can provide up to 300Mbps aggregate throughput.

Point to multipoint base station

Point to multipoint wireless Ethernet bridges use a hub spoke configuration using a Base Station Unit ("BSU" or "AP") that communicates with multiple Subscriber Units. This is similar to a cellular network where multiple mobile devices talk back to a cell tower location. Point to multipoint wireless backhaul systems are ideal for interconnecting campus buildings, security systems, control systems, IP video surveillance cameras, WISP applications, integrating remote business sites, or installing last mile connections. Point to multipoint wireless bridges operate in the unlicensed wireless frequency bands of 900MHz, 2.4GHz, 5.3GHz, 5.4GHz, or 5.8GHz. Point to multipoint wireless Ethernet bridges can provide up to 300Mbps aggregate throughput.

Wireless mesh configurations are used to create a wireless network where a radio node can communicate with two or more other wireless mesh nodes. Wireless mesh networks offer great redundancy. If one wireless mesh node can no longer operate, all the other wireless mesh nodes can still communicate with each other, directly or through one or more intermediate outdoor wireless bridge links. Each wireless Ethernet bridge link can send and receive messages in a wireless mesh network. Each link also functions as a router and can relay messages for its neighbors. Through the relaying process, a packet of wireless data will find its way to its destination, passing through intermediate links with reliable communication.

Mesh wireless backhaul networks are typically configured in a star topology or can be in a daisy chain configuration. They are used a lot in networks for wireless video backhaul and municipal wireless networks. Wireless mesh radios operate in unlicensed wireless backhaul frequencies like that of point to multipoint wireless bridges and can provide up to 300Mbps aggregate throughput.


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