n a hypothetical word-association game, "wireless" would, we’re sure, almost always be followed by "radio". No surprise here – wireless communication has its basis in radio technology, that which makes mobile connectivity possible in the first place. But equally – if not more – important to the success of any wireless network is the remainder of the implementation value chain, beyond the radio itself. This includes the (typically IP-based) elements that provide essential operational network capabilities, and, as we’ll discuss below, many other functions that create the real value for operators and, ultimately, the users of any wireless network.
The enterprise world has long been the beneficiary of a trend towards standards and open systems that began more than 20 years ago. IP is now the only protocol that matters, and common hardware interfaces, most notably related to the various incarnations of Ethernet, have also enabled unprecedented flexibility in configuration, performance, and mission applicability even over extended periods of time. Network planners, designers, and operations staff today take the mix-and-match nature of modern network equipment for granted, and it would be difficult to conceive of building any enterprise network solution without the high degree of flexibility and the many other benefits inherent in this approach.
Wide-area communications networks, on the other hand, have not been quite so fortunate for most of their history. Indeed, the proprietary nature of the core technologies in both wired and wireless WANs was inherent in both the technologies of the day and the business plans of those involved. Today, however, the trend is very much in the opposite direction, to open systems. A good example here are products now appearing in the WiMAX market, representing the leading edge of the fourth generation (4G) of wireless WANs which will in fact be defined by open interfaces and IP. In addition to defining the first 4G wide-area wireless technology, WiMAX system architecture represents thinking very much in line with contemporary communications network design – open, highlydefined interfaces with all of the flexibility, adaptability, configurability, and performance implied. Such opens new possibilities across the board to carriers and operators, the subject of this White Paper.
A Brief Introduction to WiMAX System Architecture
WiMAX is a set of specifications created by the WiMAX Forum [http://www.wimaxforum.org/ home/] and based on standards developed by the IEEE 802.16 Working Group (WG) [http:// grouper.ieee.org/groups/802/16/]. There are two standards of note here. The first is IEEE 802.16- 2004, sometimes called 802.16d, which specifies a common air interface for fixed (both ends stationary) microwave equipment. But since the high-growth market opportunity for wireless of any form today is in mobile systems, the 802.16 WG subsequently issued 802.16e-2005, which specifies a mobile broadband technology. 802.16e, as it is commonly known, is now seeing significant product development and production deployments on a global basis. Farpoint Group expects that effective per-user throughput of 2-4 Mbps will become common on carrier WiMAX networks over the next few years, with monthly pricing perhaps below that currently charged for mobile broadband services with far less throughput. WiMAX will also become a platform for application deployment and could even be catalytic in the broad availability of Web services and software as a service (SaaS), which Farpoint Group believes will become the dominant model for IT in the future – mobile or not.
The WiMAX Forum has specified a number of interfaces (see Figure 1), known as R1, R3, and R6, that provide a clear delineation between the key functional elements of a WiMAX network. These include subscribers, radio base stations of various types and capacities, and external networks and their content and services. Of particular importance is the R6 interface, which connects the radio network to external networks via a key component – the Access Service Network (ASN) gateway. ASN gateways have long played a role in both wired and wireless networks, but the range of function, scale, and throughput required of them has grown significantly over time. The advent of WiMAX creates numerous opportunities for open-systems gateways with tremendous functionality, opening new possibilities for operators (and, again, their customers) to gain from a fundamental expansion of services and performance – assuming, as we’ll cover shortly, a gateway of sufficient capacity and configurability to realize this goal.
