Considerations for service providers deploying
WiMAX, Wireless Mesh and Wi-Fi
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Pankaj Manglik is President, COO and Board Director of Terabeam Inc. and its wholly owned subsidiary, Proxim Wireless. Proxim is a global pioneer in developing Wireless Mesh, and WiMAX products for enterprises, governments and service providers. Prior to Proxim, Manglik was cofounder and CEO of Aruba Wireless Networks, a worldwide leader in wireless LANs. Aruba Networks created a new market segment called Wireless LAN Switching. Aruba is funded by Matrix Partners and Sequoia Capital. At Aruba, he raised two rounds of funding, built a worldwide organization and took the company from inception to early revenues. Previously, Manglik held senior marketing management positions at Alteon WebSystems through its IPO and successful acquisition by Nortel Networks. Prior to that, Manglik directed the marketing of Cisco’s Stratacom data/voice/video switching platform increasing revenues to $400M.Previously, Manglik ran Intel’s network engineering and design organization becoming the youngest manager in his division. He holds an MBA from the Wharton School of Business, in addition to Bachelors and Masters degrees in Electronics Engineering and Computer Science.
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The last five years have seen wireless LANs being deployed in a ‘LAN replacement’ model, and various ‘scenarios’ in North America show that they have become nearly ubiquitous. More recently, broadband wireless technologies are making a strong showing with real world applications and large markets.
Broadband Wireless Technologies
Unlike indoor deployments, the focus of broadband wireless technologies is mostly outdoor deployments. An end- to- end wireless network can be constructed using technologies that are available today. The 3 layers of the network architecture can be defined as Access, Distribution and Core.
If you think about how water gets to the tap inside your house, it will provide an analogy of how end -to -end wireless networks can be created. Water from the reservoir flows to a city in large pipes (Core). When it gets to the city, it is distributed to various neighborhoods using smaller pipes (Distribution). Finally, the water comes to your tap via a much smaller pipe (Access). A cost- effective outdoor wireless architecture will almost always involve the Access and Distribution layers. The Core may be a wireless network or a wired backhaul.
Let’s look at each of the layers in a little more detail. The Access layer defines how wireless access is provided. To provide wireless access you need a client that is universally accepted as a standard and will work with any vendor’s equipment. Today, that client is a WLAN client. Most laptops ship with integrated WLAN clients. We are also beginning to see smartphones with integrated WLAN clients. Hence WLAN technologies are a natural choice for providing Access to a public wireless network. In the next two years, we will also begin to see WiMAX built into client devices for wireless access. The Distribution layer requires a Point to Multipoint connection. It aggregates all the Access layer devices via ‘subscriber stations’ to a few centralized ‘base stations’. One of the key requirements of a Point to Multipoint network is the ability to provide a deterministic amount of bandwidth. QoS becomes a critical part of such a network. The Core layer is usually a Point to Point high speed network. It may be an unlicensed Point to Point network or use licensed spectrum. It is interesting to note that even in the unlicensed band, it’s possible to provide high speed robust connections since the beam width for these deployments is usually very small and hence they see little to no RF interference.
Applications for Broadband Wireless
The most popular application for broadband wireless is providing ‘Last Mile Access’. Providing Internet access to consumers via wireless and going after the DSL replacement market is generating a lot of interest in service providers. In addition to service providers, cities and municipalities are now getting into the act. Providing wireless access to its citizens via a ‘wireless mesh’ allows a city to achieve 3 goals: it provides a network for public safety services such as police, fire, medical; it helps bridge the digital divide by providing free access to economically disadvantaged citizens; and finally, it allows the city to offer wireless access as a utility, like water and electricity, and use the proceeds to fund network services.
Security and Surveillance is a fast growing application. With all the global security concerns, governments are funding video surveillance in public areas which is backhauled to a monitoring center using the Distribution layer technologies. In the US, a program called RedLightRunning puts video cameras on traffic lights to catch violators that run red lights. The program has been very successful as the number of violations and deaths due to accidents have come down significantly. In the Core layer, point to point technologies may be used by arriers for cellular backhaul or for providing high speed data backhaul.
With available technologies solving real world problems, the market for broadband technology products is estimated to be worth billions of dollars as early as next year.
Distribution Layer Considerations For Service Providers
The cellular tower architecture has been dramatically successful in providing wireless voice coverage to millions of people around the globe. Voice requires 40 Kbps or lower bandwidth per connection. Due to this low usage of bandwidth, the cellular industry has been able to deploy towers with radios or ‘macro base stations’ that cover large distances and thousands of people. While this has worked for cellular, it is unlikely to work for WiMAX. The deployment architecture is expected to be a high density deployment, rather than a cellular tower type low density deployment.
The need for WiMAX is driven by the demand for data services and voice services. But it’s the demand for data that makes WiMAX deployments different. The bandwidth requirements for providing data services will be much larger than for voice. Simply put, bandwidth/user is much higher for data than for voice. Let’s compare what happens to voice and data services with a macro base station architecture. As you get further away from the tower and the macro base station, the amount of bandwidth available to a user starts to decrease. For voice applications, this is not a problem. Even on the fringes of the network, there is enough bandwidth to provide voice connectivity to many users. However, the data application is a wired replacement application. While there is abundant bandwidth near the base stations, the shared bandwidth at the fringes of the network quickly makes this a non -viable option to compete with DSL and other wired technologies.
WiMAX Pico Cell Deployment Architecture
To enable high bandwidth locally and increase spectrum reuse, we must use the lessons learned in wireless mesh deployments. pico base stations and subscriber stations can be deployed in neighborhoods in greater density and closer together. These will have a smaller cell size. Decreasing the size of the radio cells will allow for spectrum re-use. Smaller cells will also cover fewer people, thus providing higher bandwidth per person. Our experience has been that a pico cell architecture is less expensive, more robust, doesn’t require air conditioning, uses less power and can possibly be run off solar power. Equally important for service providers, a pico cell architecture can be rolled out in phases with a ‘pay as you grow’ model. Since it is relatively inexpensive to deploy a pico base station and subscriber units, a service provider can test a service to see how successful it will be without a huge outlay in capex.
The Holy Grail: Mobile WiMAX
As anybody who follows WiMAX will tell you, the ultimate goal is to have client devices that have WiMAX integrated with roaming capabilities. This should happen in the next 2 to 5 years. Intel is driving towards putting WiMAX on the laptops. The CEO of a GSM chip manufacturer while placing accent on WiMAX is looking at triple-mode phones in the short to medium term. Smartphones will have celluar, WLAN and WiMAX interfaces. In short, there will be a time in the future when we will be able to leverage mobile WiMAX. The IEEE standard making all this possible is 802.16e. However, till that happens, we can still deploy WiMAX networks and get all the capabilities of roaming with wireless. While WiMAX clients are not ubiquitous, there is a wireless technology that supports roaming and is ubiquitous around the globe: 802.11 or Wi-Fi. By deploying Wi-Fi/Mesh as the Access technology and WiMAX as a Point to Multipoint fixed distribution technology, service providers can offer rich and mobile data services to consumers today. As devices with integrated WiMAX clients come on the market, upgrading the fixed network to a mobile network will require a simple software upgrade.
It’s Not All About The Technology
In our business, we all tend to get enamored by new technology and new features. Those are important and the lifeblood of our industry. However, there are some non-technical but critical things to keep in mind when deploying gear for outdoor broadband networks. It takes time to figure out all the problems that an outdoor wireless network can have. The effect of the seasons, with cold, heat, dust, and rain places great demands on equipment that needs to work more reliably when conditions are bad. Service providers should choose vendors that have deployed thousands of units for two of more years in different outdoor environments so that they don’t end up being the first ones testing a new vendor’s gear and equipment.
Summary
Broadband technologies are solving real world problems and enabling applications with strong return on investment for service providers. WiMAX is here to stay and will eventually change the face of how data services are delivered to consumers. In the meantime, service providers and vendors need to take a hard look at their deployment architectures and capex outlays. The conclusion that can be drawn is that pico cell architectures are the way to go with WiMAX.
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