Overview

The latest in technology are WiMAX wireless networks. We’ve heard so much about this wonderful new long distance wireless technology that it almost seems like it’s just a phone call away from having yours designed and installed. Long before you start assuming things like we all do, we thought that as network engineers and architects we would share personal experiences, and the experiences of colleagues around the world, in a direct, helpful, educational, and certainly grounded in reality way. . This is a basic pocket manual for anyone dealing with the implementation of a WiMAX network.

First of all, there are several misconceptions around WiMAX that need to be cleared up so that the business aspects and the engineering base have a common understanding.

Second, the people who make the various decisions within their organizations must understand that there are differences between a private network and an interoperable network strategy. This subtle difference exists and requires a plan that considers the final aspects of the transition, if considered now, to easily provide a lower-cost upgrade to a truly interoperable network, now incorporating equipment from multiple vendors.

Finally, while WiMAX has been available internationally for several years, it is very new in the United States, only a few months old, with very little training and education available to those who have the responsibility of building these systems or those who will do the installation. financial and technical decisions to have these systems built for them as part of their long-term wireless strategy.

Our experiences and the experiences of our colleagues are offered here as contributions, as well as linked to standards and certification authorities, all in the interest of providing a reality-based, quick-reference education for anyone involved in How to Build a WiMAX network.

primer

WiMAX is a standard designed for fixed broadband wireless access with a controlling base station, connecting subscriber stations not to each other but to various public networks, such as the Internet, linked to that base station. The acronym stands for “Worldwide Interoperability for Microwave Access” or (WiMAX).

WiMAX, as a standards initiative, is based on a “profile set” that supports a wide range of frequencies (up to 66 GHz) with channel sizes (1.25 MHz to 20 MHz) and applications (LOS and NLOS), and finally PTP and PTMP. WiMAX profiles reduce the scope of 802.16 to focus on service-first specific configurations. The IEEE titled the specification 802.16 and published it in December 2002. The profiles addressed in that “profile publication” are 802.16-2004 (old d) and 802.16e as listed below.

The WIMAX Forum was formed eight months earlier, in April 2002, to support, promote, and certify the compatibility and interoperability of devices based on the 802.16 specification and to develop such devices for the market. Founding members of the organization include Airspan, Alvarion, Analog Devices, Aperto Networks, Ensemble Communications, Fujitsu, Intel, Nokia, OFDM Forum, Proxim, and Wi-LAN.

WiMAX is the IEEE 802.16 point-to-multipoint broadband wireless access standard for systems in the indicated frequency ranges. WiMAX will initially provide fixed mobile, nomadic and portable wireless broadband connectivity. For this there are two standards (802.16d (new -2004) and 802.16e respectively) although both will perform similar functions because they must be interoperable. One is clearly a fixed solution and the other is a mobile solution that still has to communicate with a fixed solution. So one of the first considerations is whether you want to build a mobile or fixed network. In many cases, you would have already considered your target market segments, spectrum availability, regulatory constraints, and your need for deployment.

Which one do I need?

In general terms, today’s 802.16-2004 (originally 802.16d) fixed network products are less complex than 802.16e mobile network systems because: they can be used in a wider range of unlicensed bands, they offer faster time to market faster and, in many cases, higher performance than 802.16e equipment. On the other hand, there is better support for mobility and a wider range of terminal form factor advantages of 802.16e equipment.

It’s certainly a consideration, but no matter what you choose, migration paths to move in either direction are easily achieved through overlay networks, software-upgradable base stations, dual-mode devices, and dual-mode base stations. This consideration ensures that you are not stuck in one mode or the wrong mode and that your initial investment is protected. It makes the CTO and the CEO happy.

WiMAX base stations transmit up to 30 miles, but because it’s a cell-based topology, it would produce a more typical range of 3-5 miles. WiMAX systems can offer a capacity of up to 75 Mbps per channel, for fixed and portable access applications. This is enough bandwidth to simultaneously support hundreds of businesses with T-1 speed connectivity and thousands of residences with DSL speed connectivity, as we have seen.

WiMAX technology is expected to be incorporated into laptops and PDAs in late 2006 and early 2007, allowing urban areas and cities to become “MetroZones,” the new buzzword, for wireless access. outdoor broadband laptop Additionally, WiMAX technology is being embraced by wireless service providers and telecommunications equipment industries due to its tremendous cost advantages in bringing that last-mile connectivity to large parts of the world that are too expensive to serve with wired technologies that require all those ditches.

Security

Due to the security issues with WEP in the 802.11 Wi-Fi arenas, standards bodies took no chances with WiMAX and wisely prioritized security from the start. Base station designers went to work to ensure a dedicated, high-performance security processor. The WiMAX security standard requires that all traffic be encrypted with CCMP (which is Counter Mode with Cipher Block Chaining Message Authentication Code Protocol).

According to the WiMAX forum, the goal of the group is end-to-end authentication. WiMAX uses PKM-EAP (Extensible Authentication Protocol), which is based on the TLS standard following public key cryptography. Having addressed this level of security from the beginning provides an excellent reference point for adding multi-level security options as well, if your implementation requires an MLS approach. Secure (blacker) implementations would require such an approach.

What is released?

The first version of certification for fixed 802.16-2004 is now available and includes products from certified vendors with two profiles in the 3.5 GHz and 5.8 GHz bands that support fixed and nomadic access. Profiles for mobile 802.16e are not available or published as of this writing, but are expected to be in the 2.3 GHz to 2.5 GHz ranges when officially released. WiMAX profiles based on 802.16-2004 are better suited to fixed applications using directional antennas because OFDM is inherently less complex than SOFDMA used in mobile application. As a result, 802.16-2004 networks will be deployed much faster and at lower cost. Our experiences are with these systems launched in the US and around the world in land applications, mobile military, public safety, and maritime applications.

Planning for WiMAX

Companies, cities or projects in maritime or land systems in the US that have decided or are considering building and operating a WiMAX network will have some important issues to consider. The initial spectrum for WiMAX in the US is unlicensed spectrum in the 5 GHz range. Since this spectrum is open, it will have interference issues and inherent risks that will require attention. There are many ways to overcome interference problems. The answers come from proper site selection, after your RF survey training, and from the actual selected equipment. Therefore, the results of planning and site inspection remain the key to your sure success.

Summary

WiMAX provides optimized solutions for fixed, nomadic, portable and mobile broadband wireless access. There are two flavors in various release and deployment modes. The first is 802.16-2004 WiMAX with two initial frequency profiles: the 3.5 GHz and 5.8 GHz bands that now support fixed and nomadic access in LOS and NLOS environments. The other type is WiMAX 802.16e with expected profiles in the 2.3 GHz and 2.5 GHz ranges optimized for dynamic mobile radio channels supporting hands-free and roaming, coming in 2007. Another exciting technology for all of us. Have fun!
an extended version of this Manual is presented in our electronic magazine OnLine-CTO.
Contact Gina Smith at [email protected]