Alpha Omega Wireless Blog

There is an ever-growing need to provide high speed IP bandwidth in mobile applications. One of the greatest challenges is how to deliver broadband connectivity to moving objects, whether it be passenger or commercial rail, vehicles, watercraft, or unmanned moving objects. Since there is no way to physically cable a moving object, wireless connectivity is the solution.

Wireless mobility can provide IP bandwidth that can be used for video surveillance backhaul, vehicle and sensor monitoring, remote vehicle control, on board Wi-Fi, computer connectivity, Smart devices like phones and tablets, voice communications, vehicle location tracking, transportation management, or public announcement systems.

Different wireless technologies can be used for mobility applications, such as: wireless mesh radios, point to multipoint wireless backhaul, WiMax, LTE, and radios designed for mobility handoff. There are a lot of wireless manufactures that claim to have broadband radio systems that can provide wireless mobility. Using the right radio equipment is important for the needs of the application. Some applications need extremely low latency while others are more concerned with the amount of bandwidth provided.

The main question is what is the mobility application? Many industries, like utilities (water, oil & gas, and electrical), government (city and county), first responder (law enforcement and fire), etc. all have needs for mobility applications beyond two-way radio and cellular connectivity. Is there a need for IP network connectivity back to the organizations data network and need for Internet connectivity? The problem with using cellular LTE is the reoccurring costs and having to manage so many plans. There is also no control over how employees are using the consumed data amounts on the plans. Security is also a huge issue when using public networks versus being able to control a private network that has no other access outside the organization.

In may cases organizations want to have both fixed and mobile applications, like a utility or city that needs to have bandwidth at fixed locations around a geographic area but also want the ability to have bandwidth in their vehicles. There is a huge cost savings by having the ability for employees to be able to be connected to the home office while traveling around a service area rather than having to drive back and forth to get information. This can be getting email in the field, being able to pull work orders, upload video or pictures, get access to site plans, and so on.

Applications that have needs for both fixed and mobility can benefit from using technologies like private LTE or licensed WiMax technologies. These technologies allow for 360-degree coverage capability with a reach upwards of 20 miles around a geographic area. Bandwidth can reach up to 40+Mbps.

There are some great radio systems now that can connect to a private LTE/WiMax network and can also if need be roam onto existing cellular networks as they roam outside a good coverage area. These systems can also provide in-vehicle Wi-Fi providing connectivity to laptops, tablets, and smart phones.

In other cases like transportation such as rail, both passenger and cargo, the use of mobility handoff systems that are fixed can provide a better solution. In this case the coverage area is more linear. Using directional radios allow for better performance and more control of the use of spectrum efficiency. It’s possible to get over 100Mbps with zero packet loss and less than 2ms of latency

The unique technical challenge is providing seamless hand off as a moving object passes wireless backhaul node locations. There needs to be seamless handoff at low latency so that data connectivity isn’t interrupted. This is just like the use of cellular networks that provide connectivity with out drops as you are traveling down the road in a car and talking on the phone. The key elements in a successful wireless mobility solution are proper wireless network design, accurate wireless path engineering, wireless spectrum analysis to determine appropriate frequency utilization, hardware choice and configuration, and most importantly is the quality of wireless installation.

As a country we have relied on fiber communications as our primary means of wide area network connectivity. Fiber though is extremely expensive to provision due to right away access, permitting, construction, labor, and cost of material.  Meanwhile a lot of other countries have leap frogged the USA by deploying fixed wireless microwave communications. Many countries around the world are deploying wireless bridge microwave backhaul as their primary backbone telecommunications network. The costs of deploying a point to point wireless bridge can have a ROI of less than three months compared to even leasing fiber that is pre-existing.

Wireless backhaul can be deployed in a matter of weeks if not days. Wireless bridges such as unlicensed 5.8GHz point to point wireless and point to multipoint wireless, in 5.8GHz and 3.65GHz WiMax can be purchased off the shelf and installed in a few days. Licensed microwave communications in the form of a point to point wireless bridge, also called fixed wireless bridges, can be obtained and installed in a few weeks. (see more information "Understanding Fixed Wireless Backhaul Configurations")

With advancements in technology and newer regulation from the FCC, wireless Ethernet bridge systems can deliver over GigE (more than 1Gbps full duplex) throughput. Equivalent to that of fiber. A fixed wireless microwave link can go upwards of 50 miles. If proper wireless system design is done, a fixed wireless Ethernet bridge can provide a predictable reliability of 99.999% uptime. That's less than 5 minutes of predictable outage a year.

Most people don't think about the fiber once it leaves their building or know the path it takes. Fiber in urban areas runs inside sewer lines, underground conduits, and aerial on phone and light poles. In rural areas fiber mostly runs aerial along telephone and electric poles. Ever drive down a road and see a bunch of wood telephone poles leaning from side to side? Well that might just be the fiber your network is running on.

Ever question how long it takes for a telecommunications company to do a truck roll to repair a cut fiber? If it's a clean break fiber can sometimes be fusion spliced back together. In most cases where a fiber pole goes down or gets ripped out by a backhoe, the fiber gets stretch and has to be replace but cutting it at two ends and a new piece fusion spliced back in. This can take hours if not days to accomplish. What would be the cost to your business if that occurred?

Microwave communication can be in the form of a point to point wireless backhaul, a point to multipoint wireless bridge, or a mesh wireless Ethernet bridge. If a microwave radio fails it can be swapped out in the matter of minutes (provided a spare is maintained). After an earthquake or other natural disaster, a wireless system can be realigned immediately getting communications back up and running.  The biggest concern with wireless backhaul is the potential for wireless interference. Using a licensed microwave link can solve any interference concerns.(See more information "Wireless Backhaul Can Prevent Network Outages")

In order to get broadband across the USA at any reasonable time frame and at realistic costs we must turn to wireless backhaul technology. Fixed wireless, using both point to point wireless bridges and point to multipoint wireless (LTE and WiMax) can help expand our wide area network reach with carrier grade performance and reliability.

Is there still value in deploying a city wide outdoor wireless Wi-Fi network? Every day there the number of people that use mobile devices that are Wi-Fi enabled continues to grow. The demand for high speed connectivity to the internet is in high demand. So there is definitely a business case for it.

Many cities have tried a wireless installation to provide complete city wide Wi-Fi connectivity and have failed. In many cases the city governments, that have no staff trained and experienced in outdoor wireless backhaul and outdoor Wi-Fi systems, that tried to deploy the outdoor Wi-Fi technology rather than an outdoor wireless backhaul or mobile carrier provider, that does have experience and knowledge in mass deployments of RF and microwave communications.

Three major reasons why many of the outdoor Wi-Fi attempts failed are because there was no clear business model, projects were attempted without using highly skilled outdoor wireless installation and wireless engineering integrators, and a complete lack of understanding in the costs associated with deploying and maintaining an outdoor Wi-Fi system. Technically, it is very difficult to deploy the amount of wireless access points needed to provide complete RF coverage without causing self wireless interference. It can be done but so often wireless engineering was an afterthought when it should have been the first step.

On the other hand, WiMax backhaul promises high speed wireless connectivity to mobile devices and has already been deployed around the world with great success. WiMax backhaul, as a standard, was originally designed for outdoor wireless connectivity where Wi-Fi is a standard for indoor wireless connectivity. WiMax can cover much farther distances, requires much less infrastructure, is cheaper to deploy, wireless installation is easier, and is more cost effective to maintain. The problem is that there are not a lot of devices that are equipped with WiMax chipsets yet.

Over the years, there have been a lot of quality wireless manufactures that have come to market with outdoor wireless communication products for either outdoor Wi-Fi or WiMax solutions. Companies like Xirrus (who probably has the strongest outdoor Wi-Fi solution) and BelAir Networks have great solutions for outdoor Wi-Fi deployments. There are many others like Proxim, Motorola, and Aruba to name a few that have outdoor Wi-Fi solutions too. Companies like Alvarion, Motorola, Proxim, and Solectek to name a few make WiMax backhaul base stations and subscribers.

For the 2012 Olympics, London has declared that they will have a city wide outdoor Wi-Fi network. The services will not be offered for free but will allow tourists to stay connected to the world during the games. It is unclear who will be responsible for deploying the Wi-Fi network and who will maintain it after the Olympics. Will the City of London sell the network to an internet provider or mobile carrier or will they become a large WISP themselves. The hopes is that they will have a solid business model and will have the network designed and the wireless installation done by a credible wireless integrator. The one thing for sure is that both WiMax backhaul and outdoor Wi-Fi technology will provide a lot of benefit to the users of mobile wireless connectivity.

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.

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!

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.

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 Forum^TM) 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...

The one thing that most people don't understand is the industry background between WiMax backhaul and LTE wireless networks.

WiMax backhaul was originally developed by outdoor wireless backhaul manufactures as a way to provide fixed last mile outdoor wireless bridge connectivity. These were wireless Ethernet bridge players like Alvarion and Proxim (funny how many of the WiMax 802.16 standards, like OFDM, were already found in their existing product lines). Other players like Intel, who has a big stake in IP based technologies, joined the forum. The early intent, of those pushing the WiMax 802.16 standard, was to get the FCC to open up the 3.5GHz space for point to multipoint wireless backhaul. This was to serve the WISP (Wireless Internet Service Provider) market place. Part of the equation was to make mobile devices (like laptops and mobile phones) equipped with WiMax chipsets so they could become an actual subscriber unit (a CPE device) and connect directly to a WiMax point to multipoint wireless base station array.

The one major issue many manufactures of point to multipoint wireless bridges were facing was that they were also providing point to point wireless backhaul in the unlicensed wireless backhaul space and providing outdoor Wi-Fi solutions. Wireless interference is becoming a huge issue in the outdoor Ethernet wireless bridge space when you start using unlicensed wireless bridges (like 5.8GHz wireless backhaul) to serve unlicensed point to multipoint wireless bridges, which then provide Wi-Fi access in unlicensed 2.4GHz (802.11b/g/n) and 5.8GHz (802.11a/n). WiMax equipment if offered in a separate frequency band like 3.5GHz would open up a lot of outdoor wireless backhaul spectrum.

It wasn't until later that WiMax backhaul evolved to the mobile carrier space. Carriers, both fixed wireless and mobile, have adopted WiMax as a technology that they could readily deploy cost effectively to provide the last mile connectivity with greater bandwidth. The other advantage of WiMax backhaul is that IT people (that understand IP networking) can easily take part in outdoor wireless backhaul network deployments because they understand the IP networking background required for WiMax backhaul networks.

LTE was the evolution of the carrier's TDM transport to gain broadband to mobile devices. Many carriers like LTE because it's just an evolved technology of what they are already using. LTE is a natural progression from 2G / 3G and allows fall back. When a mobile device roams out of quality signal strength of an LTE (4G) network it can easily fall back to 3G or lower speed connectivity. Another advantage of LTE over WiMax is that LTE offers less wireless backhaul latency. WiMax backhaul uses a bigger overhead in packets. Many of its supporters are the manufactures that have been part of the mobile market all along.

WiMax backhaul has gained great ground recently worldwide because the equipment is very inexpensive and can be readily deployed for both fixed wireless backhaul and mobile broadband applications. WiMax backhaul equipment can literally be purchased any day of the week form a wireless installation company or wireless distributor. Most outdoor wireless installation companies have equipment on the shelf. Although LTE is a natural progression for carriers that have an existing 2G / 3G networks, countries that do not have a built out cellular network, WiMax backhaul is an easy choice to jump to.

One big difference is that LTE is solely a licensed microwave technology that carriers are utilizing their existing licensed spectrum, where WiMax backhaul is mostly unlicensed (at least in the USA with the exception of a small slice of spectrum in the 3.65GHz space). Many carriers are having the WiMax backhaul manufactures produce outdoor wireless point to multipoint radio equipment that will work in their licensed bands.