Home Asia-Pacific II 2008 WiMAX – the challenges of new technology

WiMAX – the challenges of new technology

by david.nunes
Ben CardwellIssue:Asia-Pacific II 2008
Article no.:10
Topic:WiMAX – the challenges of new technology
Author:Ben Cardwell
Title:Vice President, Sales and Marketing, Asia-Pacific
Organisation:Andrew Wireless Solutions
PDF size:220KB

About author

Ben Cardwell is the Vice President of Asia-Pacific for Andrew Wireless Solutions, responsible for sales and marketing in the Asia-Pacific region. A 17-year veteran of the telecommunications industry, Mr Cardwell was previously Director, Systems Engineering, Asia-Pacific for Andrew. Prior to joining Andrew, he served in various leadership positions in research & development, product management, systems engineering, and field sales with UTStarcom, Ericsson, and 3Com. Mr Cardwell graduated from Davidson College, North Carolina with a BSc in physics. He also holds an MBA from Kellogg Graduate School of Management, Northwestern University.

Article abstract

WiMAX, like any new technology will face a series of roll-out challenges. WiMAX has no existing infrastructure to take advantage of; it is a wholly new standard and, as such, new companies without existing infrastructure or customer base most often adopt it. There are still issues regarding handoffs between mobile carrier and fixed WiMAX networks, and inter-network billing to be resolved. In addition, given the transmission characteristics of the spectrum WiMAX uses, coverage inside of buildings will present a challenge.

Full Article

Infocomm technologies had barely finished making the leap from wired to wireless networks when wireless technologies began evolving. Wireless has continued to evolve at breakneck speed, fuelled by the growing ranks of increasingly mobile consumers, who demand network access on the go as they migrate from voice to data-centric applications. The number of mobile subscribers in the Asia-Pacific crossed the one billion mark last year, having grown at a staggering compound annual rate of 24 per cent from 2002 to 2006 (Frost & Sullivan). Operators in the region face the challenge of wooing and retaining customers while keeping roll-out costs in check, but this can be a tricky balancing act, especially for greenfield technologies such as WiMAX. In the past decade, users have come to expect predictable, incremental improvements from each new generation of wireless data communications. Like advancements in other fields, much of data communications stand on the shoulders of earlier technologies. Today’s third-generation wireless networks followed developmental paths dictated by their family origins – UMB, EVDO, and its A, B and C revisions, all evolved along the CDMA developmental path, while UMTS, HSxPA and LTE trace their roots back to GSM technology. Carriers moving to 3G and beyond via these routes can leverage these older technologies and, to a certain extent, their existing infrastructure. In contrast, mobile WiMAX is a new standard developed by the 802 IEEE workgroup. Unlike GSM- and CDMA-based data networks, WiMAX deployments will be greenfield implementations that offer operators fewer opportunities to use existing infrastructure than they would have moving from advanced second-generation wireless technology to third-generation technology. Then, too, many mobile WiMAX operators will be companies just entering the market that do not have an existing customer base they can depend on to trade up to a new technology. The newness of mobile WiMAX means certain technical issues await resolution by industry groups, even as deployment moves ahead. These issues include questions regarding handoffs between mobile carrier and fixed WiMAX networks, and inter-network billing. Although mobile WiMAX operators face the challenges a new technology brings, shareholder expectations for revenue growth and profitability will be similar to those placed on their more established brethren. This mandates an accelerated adoption timetable with little forgiveness for missteps. Nevertheless, given this environment, WiMAX operators may well choose an aggressive build-out strategy that creates a national network much faster than the traditional 2.5G-to-3G expansion model. All next-generation wireless deployments – 3G HSPA, EVDO or WiMAX, which focus on data-centric business models – pose distinct challenges for the operator. Several factors will determine their success as viable data communications network alternatives: • The emergence of a ‘killer application’ that is either totally new to wireless communications, or that can be done better or faster using a wireless data device; • Service levels (speed, accuracy) that the typical user can clearly see are superior to those of competing networks; and, • Pricing that is low enough to make it worthwhile to switch from another network or lower than the cost of upgrading to a higher tier of services on an existing network. Many of the high-speed wireless data applications that will go on the market first – e-mail, specialised business software, and video – are most likely to be used indoors. Applications that require high bandwidth often require a large screen to be easily seen and navigated. Unlike many 2G-based data networks, many mobile next-generation data network operators will have a difficult time achieving expected indoor coverage from their outdoor base stations. The nature of high-speed wireless data transmission, coupled with the challenging propagation characteristics of the higher frequencies traditionally allocated to 3G and WiMAX, mandates specialised indoor solutions such as pico-cell base stations, femto cells, [pico = one trillionth; femto = one quadrillionth] intelligent repeaters and distributed antenna systems. The best solution for indoor and public venue deployment will depend on the size of the area involved and the number of users served. WiMAX pico base station – This solution offers the advantages of low visibility and relatively high output. Picos are small in volume (5-15 litres) and low in weight (4-10Kg), enabling unobtrusive deployment on walls. Output is typically in the 100-300mW range. They are a good solution for indoor hotspots such as in train stations, high-rise buildings and airport waiting rooms. Their deployment, however, can create problems integrating with the larger macro network; the issue is whether in-building coverage can be maximised without interacting negatively with the macro network. Resolving this often requires complex integration work that can degrade call quality if not done correctly. In addition, several Pico nodes may be needed to provide continuous coverage inside a building, adding another layer of complexity. Further, if traffic patterns in a building change, the Picos may have to be moved and the network redesigned. Femto cells – Femto units are designed for smaller areas, typically homes or small businesses, and can often be installed by homeowners or carriers themselves. With output in the range of 1-100mW, they can offer a new portfolio of wireless DSL-like services for the home, but they too may present challenges in terms of integration with existing wireless infrastructures. Intelligent repeaters – These devices receive, amplify and retransmit RF signals on both the uplink and downlink. Intelligent repeaters monitor their environment and can adapt the RF signal to maximise coverage and minimise interference. Because repeaters connect to the operator’s network via radio links, costly backhaul circuits are eliminated. Through focused coverage design, they can extend coverage in-building while limiting interference that spoils the users’ wireless experience. While intelligent repeaters provide a relatively straightforward solution to indoor coverage issues, power output must be monitored to avoid desensitising serving base stations, leading to diminished performance. Active and passive distributed antenna systems (DAS) – These systems are designed to connect nodes to hard-to-reach, high-traffic areas in buildings, malls, stadiums and convention centres. For a structure owner and operator, they offer expanded service options that are carrier-neutral. A DAS uses a network of cables, couplers, power splitters and amplifiers to distribute RF signals to multiple antennas throughout a building. There is also the option of deploying an active DAS where optical cable connects the antennas to the base station or repeater. This requires conversion of RF communications to optical signals, usually relying on direct modulation, which provides very high bandwidth. This solution makes the most sense for buildings larger than 23,000 square metres in area. A second option for DAS in smaller structures is a passive system that uses coaxial cable instead of optical fibre. The coaxial cable can be modified to let the RF signal radiate along its length. For WiMAX, such a solution offers greater reliability and lower initial cost. While a passive DAS can operate with multiple technologies, it has limited bandwidth and often needs greater power to drive the network. Hefty backhaul requirements Early projections for broadband wireless services indicate that even basic initial packages could bring a three-fold increase in backhaul traffic. Should optional services involving Web video, large-graphic file sharing, or mobile e-commerce gain popularity, those projections could prove conservative. If this occurs, solutions based on traditional terrestrial architecture could be expensive and have a painfully long time-to-market. In this environment, microwave links used to move ‘last mile’ traffic to and from the base station may be a better choice. Site sharing One of the best ways to reduce network deployment costs is to piggyback on the infrastructure used by existing networks. Greenfield operators can form partnerships with existing 2G or 3G operators to share towers, shelters, power systems and the like, while incumbent 2G and 3G operators can leverage their previous investments in these areas. High-power active DAS solutions can also be used to reduce the equipment footprint and real-estate costs. Base station hotels can be built in a central location and shared by multiple operators and/or technologies. These systems also reduce the environmental and aesthetic impact in built-up areas, easing local government approval for new sites. New technologies, old measuring sticks Broadband wireless operators must get networks up and running rapidly to compete with other next-generation services. Because investors expect heavy outlays for a new network, this can create a relatively benign environment for capital spending. Still, carriers must keep in mind that after just a few years, shareholders will judge management’s performance and its control of operating expenses with a much more critical eye. When establishing broadband wireless services, operators must consider: • Alternatives to building base stations such as repeaters and DAS systems, to ensure in-building and public venue coverage; • Adequate monitoring of the network to track usage changes that may occur over time, and verify the network’s flexibility to adjust; • The elimination of redundancies to free up network resources for areas of growth; • Whether existing site and landlord agreements permit the addition of new technology; • Assurance of a clear upgrade path for capacity growth and future improvements in network performance; • In the case of multi-technology networks, optimisation of network usage between different technology layers; • Standardisation of equipment to minimise the number of sites and reduce operating costs; and, • Effective management of pilot roll-outs, to illuminate technical issues not apparent in controlled testing. If operators address these issues adequately, they will have a network that can maximise the acquisition and retention of customers and minimise rollout costs. This will put today’s wireless broadband technologies in a strong competitive position to meet the challenge of the fourth-generation networks deployed over the next decade.

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