Leveraging 802.16e WiMAX Technology in License-Exempt Bands

By Ashish Sharma, VP, Corporate Communications, Alvarion Ltd.

License-exempt spectrum bands make it possible for operators who do not have access to licensed spectrum to deploy wireless broadband networks. With Institute of Electrical and Electronics Engineers (IEEE) 802.16e WiMAX technologies, license-exempt operators have access to the most advanced wireless broadband products on the market today and can take advantage of performance, ecosystem and volume of scale benefits in the same way incumbent, nationwide wireless operators (with spectrum licenses) do.

Today, 802.16e WiMAX supports fixed and nomadic services, and vertical applications in a range of license-exempt frequencies up to 6 GHz, including the 5.x GHz band. As 802.16e WiMAX products for license-exempt bands are introduced in the market, operators need to understand the value proposition of using these global standards-based wireless broadband solutions compared to alternatives. And, how do operators stand to gain from a proven license-exempt technology that was developed to support mobility? Finally, what are the extra features that 802.16e WiMAX offers that are key for operators to leverage?

Evaluating Performance Requirements

Now more than ever, wireless broadband operators are under intense pressure to achieve profitability rapidly and to provide data and voice services that can successfully compete with wireline services. To achieve these goals, operators need to clearly define their requirements and carefully select the technology that is best suited to meet them.

While some requirements depend on specific applications and services, there are a key common requirements that are independent of the applications and services supported and are crucial to all operators in license-exempt bands, including:

• High capacity. The technology used has to support high data rates, which effectively bring down the bit-based cost for the overall network. High data rates allow the operator to support a higher number of subscribers within the same sector, or to provide higher data allowances to subscribers.
• Robust coverage. Operators that deploy equipment in rural or low-density areas or support services requiring only limited bandwidth typically have coverage-driven networks. Establishing good coverage can be especially challenging in license-exempt bands because they typically have lower power allowances and higher frequencies than licensed bands.
• Interference management. While levels of interference vary by area and band used, wireless operators using license-exempt bands need tools to manage existing interference or to defend their investment from interference that may emerge in the future.
• Traffic management. Wireless broadband networks are increasingly used to support voice alongside data services, to serve customers with different service plans, access priority or allowances, and to support multiple types of vertical applications. A brute-force approach of providing more bandwidth than needed to avoid managing traffic is no longer cost effective or sufficient because traffic from individual users keeps growing at a fast pace. Quality of service (QoS) and traffic prioritization and management are needed to provide fair access to all subscribers, to support voice and video data, and, more generally, to provide priority access to those applications or services that require it, on the basis of the service level agreement (SLA) in place.
• Mobility support has not yet become a wide-spread requirement, but is a feature that many operators are interested in addressing today -- even if they do not yet plan to roll out services or vertical applications that require mobile access at launch.

Alvarion’s BreezeMAX® Extreme 5000 is the industry’s first license-exempt WiMAX solution to meet operators requirements and enable the applications such as voice, broadband data and video surveillance. The BreezeMAX was designed to help speed up the deployment of broadband infrastructure into multiple market segments such as public safety, municipality operations and services, smart power grids, and government.

The case for deploying 802.16e WiMAX-based equipment

Over the last three years, 802.16e WiMAX technology has reached a point where there is a well-established evolution roadmap, with strong industry backing and a rapidly expanding ecosystemof more than 500 technology providers. The 802.16e WiMAX has a path toward the next generation in the soon to be ratified IEEE 802.16m version, which 802.16d TDD WiMAX lacks. Operators with 802.16e WiMAX-based networks will be able to seemlessly upgrade their infrastructure to 802.16m WiMAX when the equipment becomes available.

Operators using 802.16e WiMAX-based equipment in license-exempt bands can take advantage of the economies of scale achieved in licensed bands because vendors can modify the existing network equipment and devices to operate in license-exempt bands. Furthermore, having launched commercial products in the licensed WiMAX bands (i.e., 2.3 GHz, 2.5 GHz, and 3.5 GHz), some vendors are expected to extend their produce line to license-exempt bands rapidly.

Support for mobility is another major benefit of 802.16e WiMAX. The prevailing attitude among operators is that mobility is a ‘nice-to-have’ feature that gives them additional flexibility in how they market their services. From a business model perspective, operators in license-exempt bands have so far been focused on fixed services and applications. From a technology perspective, full mobility in high-frequency license-exempt bands has been a challenge.

The interest from wireless operators and vertical market players is mostly tied to the potential to offer nomadic access or limited mobility, which can be easily tied to the service currently available as an add-on service. Mobility will also enable operators to expand the range of services they offer their vertical customers within their coverage area, and to include applications that require, for instance, support for the mobile workforce or in-vehicle connectivity (e.g., for safety and security, government, utilities and transportation applications).

Finally, 802.16e WiMAX-based equipment supports advanced functionality that is conducive to improved performance compared to 802.16d WiMAX and other wireless broadband technologies. The spectral efficiency of the air interface in the two versions of WiMAX in their basic configurations is comparable, but several features that are available or required in 802.16e WiMAX are not implemented in 802.16d TDD WiMAX equipment. For example, QoS is available in both versions of WiMAX, but 802.16e WiMAX can provide better support for voice services though an additional QoS level that makes it possible to dynamically allocate capacity to voice traffic only when needed.

WiMAX deployed in license-exempt bands today

Towerstream

This operator has been providing symmetric dedicated connections to businesses in major metropolitan areas in the U.S. since 2001, accumulating deep experience in many pre-WiMAX wireless broadband technologies.

An early supporter of WiMAX, Towerstream has been conducting trials of WiMAX solutions for the last three to four years, but it was only when 802.16e WiMAX-based equipment became available that the operator decided to make the transition. Any 802.16d WiMAX-based solution would have been a temporary one, eventually requiring a forklift upgrade—most likely before the initial investment could be recouped.

Business considerations were the major drivers to select 802.16e WiMAX-based technology, but performance was also carefully assessed. QoS, for instance, is crucial to provide robust voice services. Advanced antenna technologies including MIMO A and MIMO B bring a substantial improvement in the signal strength in challenging environments.

Adam Internet

Australian operator Adam Internetis the first ISP to deploy a wireless network in partnership with the South Australian Government, which is providing partial funding for the infrastructure development costs. Adam Internet provides both broadband connectivity and VoIP services to its WiMAX subscribers at fees comparable to those for metropolitan ADSL services, which are still the core of the operator’s service offerings.

With no access to licensed spectrum at this time, Adam Internet has chosen to use license-exempt spectrum equipment. When 802.16e WiMAX-based products operating in the 5 GHz band became available, Adam Internet was eager to trial them, and has become one of the first operators to deploy a 5 GHz 802.16e WiMAX-based network, launching in Adelaide in November 2009. The network rollout is done in close collaboration between Adam Internet network engineers, who have experience in point-to-point links used to connect business users and Alvarion engineers. A combination of wireless links and fiber provide the backhaul to the Adam Internet network.

802.16e WiMAX: A Clear Technology of Choice

Whether it’s a wireless operators plan to expand their residential or business service or seeking to grow their vertical market applications, or looking for a future-proof technology, 802.16e WiMAX is becoming an increasingly compelling option for license-exempt bands. Equipment based on 802.16e WiMAX supports full mobile access, but it also supports high-performance fixed networks. Today, Alvarion’s BreezeMAX Extreme 5000 is becoming the solution of choice because of its ability to lower the cost of high-bandwidth, carrier-class broadband connectivity for a variety of applications that fit market’s specific needs.

Thanks to the wide industry support for the 802.16e version of the standard, operators using 802.16e WiMAX-based equipment will be able to rely on a stronger ecosystem than available based on limited 802.16d TDD solutions, which in turn will translate into more robust interoperability and the availability of a wider range of affordable subscriber devices.