The emergence of the WiMax standards has spurred tremendous interest from operators seeking to deploy next-generation, high-performing, cost-effective broadband wireless networks. However, the availability of 802.16e and 802.16d as two different and incompatible iterations has in some cases added confusion to the operator's investment decisions.
WiMax refers to both the 802.16d and 802.16e standards, which the Insitute of Electrical and Electronics Engineers (IEEE) said supports a variety of applications and network solutions. The WiMax label refers to a defined subset of technology specifications from the 802.16d and 802.16e standards called profiles.
Often referred to as the mobile standard, 802.16e not only introduces mobility to broadband wireless specifications, but also provides enhanced performance even in fixed and nomadic environments. Below I have outlined several reasons why 802.16e is the true future of WiMax.
Not backward compatible
Operators seeking to make a WiMax investment must first recognise that 802.16e is not backward compatible with 802.16d. While some 802.16d vendors propose base station equipment with additional hardware complexity or software programmability to allow a switch to 802.16e, this will not impact any 802.16d end-user devices already deployed. These 802.16d devices will not operate within an 802.16e network and the imperative for low-cost end-user devices makes it prohibitive to introduce additional hardware to attempt an upgrade to 802.16e compliance. Adding upgrade capability to the base station may also result in a large cost penalty.
Additionally, an operator who deploys 802.16d and then attempts to roll in 802.16e equipment at a later date will be disadvantaged by having to split the available licensed spectrum between the two technologies. Without a true upgrade path from 802.16d to 802.16e and the necessity to preserve spectrum to support network growth, 802.16e provides the best long-term protection for an operator's WiMax investments.
As the broadband wireless market continues to grow, the industry should expect to benefit from cost reductions enabled by volume deployments and economies of scale. Portable and mobile applications have a very strong track record for accelerating volume. Therefore, it is expected that mobile deployments of 802.16e will bring cost points down below solutions engineered solely for fixed applications using 802.16d.
Major chipset manufacturers have also announced that 802.16e will be the premier standard for WiMax applications, pointing to a substantial embedded base of consumer products with 802.16e support. These same chipsets used in laptops and handhelds can be leveraged in the manufacturing of indoor- and outdoor-fixed customer premise equipment. It becomes quickly apparent that 802.16e offers the critical advantage of allowing the operator to ride a downward trending cost curve.
Scalable system bandwidth
With 802.16e, WiMax makes enhancements to the physical layer by employing Scalable Orthogonal Frequency Division Multiple Access (OFDMA). The ability to scale system bandwidth while maintaining constant symbol duration provides greater commonality in equipment components and offers operators the advantage of being able to deploy today and grow their system bandwidth tomorrow at a lower cost and reduced network impact.
While both 802.16d and 802.16e standards specify various requirements and optional techniques to enable a high-performing broadband wireless channel, 802.16e, IEEE and the resultant WiMax profiles are expected to extend these requirements and options to guide vendors to further enhancements in capacity, coverage, power reduction, quality of service and support for rich IP applications.