President Senza Fili Consulting
The initial wave of worldwide interoperability for microwave access (WiMAX) certification is coming to an end, and the first WiMAX–certified products are expected before the end of the year. This is a key benchmark for the entire WiMAX community: After much hype and anticipation, we will be able to assess WiMAXperformance in real networks instead of making educated guesses from abstract specifications. These first WiMAX products, however, mark only the beginning of a certification process that will ultimately include numerous “waves” of testing. Each wave will include new certification profiles and/or new functionality to support new frequencies and different access modes (fixed, nomadic, portable, andmobile). The changes in the program are driven mostly by technological advances and product availability. They are crucial for ensuring that certified products have the functionality the market requires and can support new applications and services. Understanding how the certification process evolves is necessary if we are to have accurate expectations of certified products. Certification isoften perceived as a binary attribute: a product is either certified or uncertified. The reality is more complex. A product may be certified for only some of the functionality it supports. For instance, WiMAX products certified in the first wave will not be certified for quality of service (QoS). As a result, two certified products may work together in their basic configuration, but certifiedinteroperability would not extend to QoS. This is a substantial limitation for a service provider that wants to offer QoS–based services such as voice over Internet protocol (VoIP) and is planning to use base stations and subscriber units from different vendors. Product certification is an inherently complex process, especially when it involves interoperability among vendors, as is the case for WiMAX. TheWireless Fidelity Alliance, for instance, has been very successful in guaranteeing interoperability for certified products, but this has required a constant expansion of the number of profiles and the functionality that is tested and has taken over five years to get to where we are today. Some of the additions are certified as optional add-ons, but in some cases they soon become an integral partof the basic test suites. The WiMAX Forum is following a similar path. It is defining different system and certification profiles for classes of products that interoperate with each other, and setting subsequent certification waves, each including additional functionality. Before Certification: System Profiles and Certification Profiles
Not all WiMAX products will interoperate with eachother1. A subscriber unit that operates in the 3.5 GHz band, for instance, will not be able to establish a connection with a 5.8 GHz base station. However, both products are based on the same standards—Institute of Electrical and Electronics Engineers (IEEE) 802.16 and European Telecommunications Standards Institute (ETSI) highperformance radio metropolitan-area network (HIPERMAN)—and meet the samerequirements. The WiMAX Forum uses the following two types of profiles to address the need for different classes of products that use the same technology: System profiles—System profiles set a basic level of common requirements that all WiMAX systems have to meet. To date, only one system profile has been defined, and it is based on the 802.16-2004 version of the IEEE 802.16 standard. A second systemprofile is being defined and will be based on the 801.16e amendment. The first system profile is optimized for fixed and nomadic access; the second for portable and mobile access, but it will also support fixed and nomadic access. Certification profiles—For each system profile, there are multiple certification profiles. For the 802.16-2004 system profile, five certification profiles have been...