WiMAX Interview Preparation Guide

WiMAX Technology is an IP based, wireless broadband access technology that provides performance similar to 802.11/Wi-Fi networks with the coverage and QOS (quality of service) of cellular networks. WiMAX is also an acronym meaning "Worldwide Interoperability for Microwave Access (WiMAX).

The WiMAX Forum and to the founding members of the WiMAX Technology Forum, which committed themselves early to the process of creating a collaborative standards body. As a founding member of the WiMAX Technology Forum, Intel recognized that a well developed ecosystem was necessary to drive adoption and thereby drive lower hardware costs. Intel was also instrumental in getting other silicon chip manufacturers involved whose products would form the core of WiMAX technology.

WiMAX Technology is arguably even more important for the fixed broadband wireless segment than mobile broadband, at least internally to that industry. It seems clear that mobile broadband wireless holds the loftier long term monetary and customer growth potential. However, the fixed wireless segment has been fragmented essentially since its inception. There are no cohesive standards for outdoor metropolitan area networks beyond the adapted Wi-Fi technologies. Wi-Fi Technology as a standard has been accepted in broad strokes by the industry and the public. However, it is not a well conceived citywide technology.

Since much of the technology being utilized in the IEEE 802.16 standard (WiMAX Technology standard) is widely deployed, there is a historical body of evidence supporting the safety of technologies used in upcoming WiMAX Technology and WiMAX products. Microwave and other spectrum technologies enjoy over a hundred years of historical evidence of safety when prudently handled and configured. The amount of power allowed to deliver broadband wireless signal varies from frequency to frequency, however, most are modest topping out at around 40 watts at the tower relay site. While certain basic precautions need to be taken when onsite at communications towers (i.e. standing directly in front of active microwave links at essentially zero range) the configurations for public use are understood and safe. Customer premise equipment is even safer.

It is important to remember that WiMAX Technology is a global broadband wireless standard. The question of whether or not it could replace either DSL or Cable will vary from region to region. Many developing countries simply do not have the infrastructure to support either cable or DSL broadband technologies. In fact, many such countries are already widely using proprietary broadband wireless technologies. Even in such regions however, it is very unlikely that either Cable or DSL technologies would disappear. The business case and basic infrastructure often dictates that the cheapest solutions will predominate. In many areas in developing nations, it may be cheaper to deploy Cable and DSL in the cities at least for fixed applications, whereas WiMAX Technology will dominate outside of major towns.

To answer this question it is important to understand the state of technical fragmentation experienced in the past by the mobile wireless and fixed broadband wireless industry. Early broadband wireless systems began as extensions of indoor local area network (LAN) technology known as Wi-Fi Technology or the 802.11b protocol. This standard has evolved into a ubiquitous and widely available standard used in short range hotspots all over the globe. However, the media access controller (MAC) and physical layer (PHY) specifications for this protocol are suboptimum for outdoor citywide wireless networks or metropolitan area networks (MAN). Recent updates and new standards such as 802.11g, 802.11a and 802.11n have improved these elements. However, once again these technologies are configured for best performance in small venues and at short range.

Mobile broadband wireless or 3G has enjoyed two largely consistent standards, those being the code division multiple access (CDMA) based approach with its evolution data only (EVDO) and the universal mobile telecommunications system (UMTS) and its faster upgrade high speed downlink packet access (HSDPA), which in particular has gained some deployments in the past year. However, these technologies were slow to mature into economically viable and affordable iterations. The EVDO schema is now in a Revision A version which improves bandwidth considerably. Verizon and Sprint are the first US based carriers to begin wide deployment. Sprint currently has deployed most of its markets with 3G as has Verizon. The bandwidth limitations have been significant and the adoption by carriers, particularly those utilizing GSM technology here in the US has been very slow (as they are essentially incompatible technologies).

Clearly, WiMAX Technology and Wi-Fi Technology are complementary technologies and will remain so for the foreseeable future. The widely available Wi-Fi technology used in hotspots in hotels, restaurants, airports and even larger Wi-Fi zones in some cities will continue to grow for many years. The recent flurry of municipal Wi-Fi mesh networks has only served to cement the technology into the wireless equation. Wi-Fi is not going away any time soon.

The answer to this question probably generates more confusion than any other single aspect of WiMAX Technology. In the early days of WiMAX it was common to see statements in the media describing WiMAX multipoint coverage extending 30 miles. In a strict technical sense (in some spectrum ranges) this is correct, with even greater ranges being possible in point to point links. In practice (and especially in the license-free bands) this is wildly overstated especially where non line of sight (NLOS) reception is concerned.

The short answer is yes, as never before with broadband wireless systems. However, this area appears to be early ground that vendors are staking out to differentiate their products and philosophies. The WiMAX standard itself incorporates much better and more flexible security support than the Wi-Fi standard. It can be sometimes confusing when industry pundits and detractors talk of standards such as WiMAX Technology and then in the same breath describe ways in which vendors will be "different" or that WiMAX Technology security might be weak. At first glance, these comments on the part of some vendors zealous to promote the added capabilities of their products can leave one feeling uncertain about the quality and reliability of the product.