How to build a WiMAX network

Overview

The latest technological buzz is that of WiMAX wireless networks. We’ve heard so much about this wonderful new long distance wireless technology that it almost seems like you’re just a phone call away from designing and installing your own. Long before we started to assume things like we all do, we thought that as engineers and network architects we would share personal experiences and the experiences of colleagues around the world, in a direct, useful way. , educational and certainly reality-based. This is a primer for anyone currently involved in the implementation of a WiMAX network.

First, there are several misconceptions regarding WiMAX that need to be clarified so that the business aspects and the engineering basis have a common understanding.

Second, the people who make the different decisions within your organizations need to understand that there are differences between a private network and an interoperable network strategy. This subtle difference exists and requires a plan that takes into account the final transition aspects, if considered now, to easily provide a low-cost upgrade to a true interoperable network, now integrating various vendor equipment.

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

Our experiences and the experiences of our colleagues are offered here as inputs, as well as within the framework of standards and certification authorities, all intended to provide a quick, reality-based reference training for anyone wishing to create a WiMAX network. .

Primer

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

WiMAX, as a standards initiative, is based on a “set of profiles” supporting 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 early service specific configurations. The IEEE titled the specification 802.16 and published it in December 2002. The profiles covered in this “version of the profiles” are 802.16-2004 (old d) and 802.16e as discussed below.

The WIMAX Forum was established 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. The 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 within the frequency ranges indicated. WiMAX will initially provide mobile, portable and eventually mobile fixed wireless broadband connectivity. For this purpose there are two standards (802.16d (new -2004) and 802.16e respectively) although they both perform similar functions as they need to be interoperable. One is clearly a fixed solution and the other a mobile solution which must always communicate with a fixed solution. One of the first considerations is therefore whether you want to create a mobile or fixed network. In many cases, you would have already taken into account your target market segments, spectrum availability, regulatory constraints, and your need for deployment.

Which one do i need?

In general, current 802.16-2004 (initially 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, and in many cases higher throughput than 802.16e equipment. On the other hand, there is better mobility support and a wider range of terminal form factor benefits of 802.16e equipment.

This is definitely a consideration, but no matter what you choose, migration paths for moving in both directions are easily achievable via overlay networks, software-scalable base stations, dual-mode devices, and base stations. two-mode. This consideration ensures that you are not stuck in one or the wrong mode and that your initial investment is protected. Makes the CTO and CEO happy.

WiMAX base stations transmit up to 30 miles, but since this is a cellular topology, they would give a more typical range of 3-5 miles. WiMAX systems can provide a capacity of up to 75 Mbps per channel, for fixed and portable access applications. That’s enough bandwidth to simultaneously support hundreds of businesses with T-1 speed connectivity and thousands of homes with DSL speed connectivity, as we’ve seen.

WiMAX technology will be incorporated into laptops and PDAs expected in late 2006 and early 2007, allowing urban areas and cities to become “MetroZones”, the new buzzword, for outdoor portable high-speed wireless access. . In addition, wireless service providers and telecommunications equipment industries are embracing WiMAX technology because of its huge cost advantages in providing this last mile connectivity to large parts of the world that are too expensive for technologies. wired requiring all this digging.

Security

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

According to the WiMAX Forum, the group’s goal is end-to-end authentication. WiMAX uses PKM-EAP (Extensible Authentication Protocol), which is based on the TLS standard following public key cryptography. Addressing this level of security up front provides a great baseline for adding multi-level security options as well, if your implementation requires an MLS approach. Secure (darker) implementations would require such an approach.

What is released?

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

Planning for WIMAX

Companies, cities, or marine or land systems projects in the United States that have decided or are considering building and operating a WiMAX network will have a few important issues to consider. The initial spectrum for WiMAX in the United States is unlicensed spectrum in the 5 GHz range. Since this spectrum is open, it will have inherent interference issues and risks that will require special attention. There are many ways to overcome interference problems. Responses come from an appropriate site selection, following your RF survey training and from the actual equipment selected. Thus, the results of the planning and the site survey remain the key to your confident success.

Summary

WiMAX provides optimized solutions for fixed, nomadic, portable and mobile broadband wireless access. There are two versions in various modes of publication and implementation. The first is WiMAX 802.16-2004 with two initial frequency profiles – the 3.5 GHz and 5.8 GHz bands now supporting fixed and nomadic access in LOS and NLOS environments. The other version 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 – arriving by 2007 Another exciting technology for all of us. Enjoy!

an extended version of this guide is featured in our electronic magazine OnLine-CTO.

Contact Gina Smith at [email protected]

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