WiMAX began as a fixed technology enabling carriers to deploy radios from base station vendors to create pockets of wireless connectivity. However, the emergence of Mobile WiMAX and its associated standards has provided carriers the basis for a compelling end-to-end solution. The reality is that the decisions made on the WiMAX core infrastructure, those pieces connecting the radios to the IP backbone, are vital to realizing the full potential of this exciting technology.

Eric Andrews

These decisions also affect the carriers where it matters most - their bottom lines. In fact, the decisions will actually come down to making the difference between an "open" or a "closed" mobile WiMAX architecture, and in the end, this difference will affect what carriers can purchase, what services they offer and most importantly, their revenue potential.

To put this in context, let's take a look at how standards are addressed in enterprise networks. Although the enterprise market has long-benefited from the adoption of open-standard interfaces, including IP, open standards are a relatively new concept for the wireless carrier market. We have seen the enterprise market enjoy decades of cost reductions and product innovation that have come with a truly open marketplace. In enterprise networks, the inability to mix-and-match IP and Ethernet technologies from various vendors to create powerful enterprise solutions is unthinkable.

Traditional wireless carriers, however, have evolved from a voice-oriented infrastructure dominated by a handful of telecom equipment vendors, resulting in relatively closed architectures. Interoperability and the ability to mix products from multiple vendors is the exception rather than the rule.

With its roots in IEEE and IP, and its embrace of reasonable intellectual property rights, WiMAX represents the potential for dramatic change in the carrier marketplace. There is the promise of choice, the promise of innovation and the promise of compelling economics. All of this can be realized if the WiMAX industry stays focused on ensuring open interfaces are maintained.

While the IEEE is largely responsible for defining the air interface between subscriber stations and base stations, the WiMAX Forum has taken on the task of specifying the "WiMAX End-to-End Network Systems Architecture" based on IEEE 802.16e, the first version of which was ratified in March 2007.

THE IMPORTANCE OF THE R6 INTERFACE
Of particular interest in this specification is the R6 interface, which defines communication between two key components in a WiMAX network, the ASN gateway and the base station. In an apparent effort to appeal to all camps, the WiMAX Forum adopted three different profiles in the first version of the specification:

• Profile A: WiMAX-defined standard interface between ASN gateway and base station, with more radio resource control functions in the ASN gateway
• Profile B: No defined interface between ASN gateway and base station
• Profile C: WiMAX-defined standard interface between ASN gateway and base station, with more radio resource functions in the base station and a focus on the air interface.

While the WiMAX Forum has done a solid job in developing specifications for the core network interfaces for end-to-end WiMAX networks, the absence of a single true "standard" for the R6 interface creates challenges for the industry:

• Incumbent telecommunications equipment providers are not always eager to embrace open interfaces. Some see this as a threat to their traditional closed architecture monopolies that have afforded them account control in the past.
• The WiMAX Forum's adoption of several "profiles" as part of its initial standard has caused some confusion in the industry and made true interoperability challenging.

Although momentum has gathered around "Profile C" as the interface between ASN gateways and base stations, the existence of Profile B offers a loophole that vendors that have no interest in open interfaces can exploit.

WHY STANDARDS ARE CRITICAL
How do standards debates affect carriers' potential revenues? The wireless core infrastructure is a critical component in allowing carriers to deploy scalable, profitable WiMAX networks. The ASN gateway, along with other components in the core, plays a central role in the carrier's ability to effectively manage subscribers, enable mobility, track accounting and billing information, differentiate quality of service and optimize network resources. Performance and scalability of these solutions are critical, which is why standard interfaces and end-to-end interoperability are so crucial. In essence, these components help determine the services that carriers can offer, and the Capex/Opex savings they can realize in their networks. 

With such a mission-critical resource at stake, it seems obvious that carriers would want the option for choice. Vendors that may be good at delivering radios and base station technology may not necessarily offer carriers the most competitive options for a high-performance IP infrastructure that enable mobile services.

For WiMAX networks to reach their full potential, the industry must be vigilant in ensuring open-standard interfaces that give carriers the freedom of choice. Open standards foster competition and innovation that will lead to profitable new service offerings.

In this election year, vote "No" on Profile B and vote "Yes" to Profile C for truly open WiMAX standards.

Andrews is vice president of Product Management for WiChorus.