WIMAX EQUIPMENT VENDORS

WiMAX, as with many new technologies, is based on an open standard. Although standards increasingly play a crucial role in driving adoption, they are not sufficient to guarantee success. A standard-based technology will success only if a solid ecosystem of operators, vendors, and solution and content providers emerge to support it, as is in the case of WiMAX. WiMAX enables intervendor interoperability which brings lower costs, greater flexibility and freedom, and faster innovation to operators.

Within the WiMAX industry there is a strong commitment to ensuring full interoperability through certification and ad-hoc testing between vendors. It is important for network operators to realize how interoperability is established and what it covers so that they understand how different products, solutions, and applications from different vendors can coexist in the same WiMAX network. The advantages that interoperability brings are multiple. Some of these advantages are the ability to choose among vendors, flexibility when choosing the appropriate network elements and components, success to the latest cutting-edge technology, and an open architecture which makes it easier for operators to roll out new revenue-generation services and applications as they can rely on wider pool of suppliers.

The two categories of equipment vendors include the network equipment vendors and the terminal equipment vendors. Network equipment includes ASN and CSN equipment, and vendors include companies such as Motorola and ZTE of China. They will gain their profits through the sale of the equipment and through installation of the equipment. They may further have after sales agreements with the customers who are the service providers. Terminal equipment includes mobile phones, CPE, modems, laptops, smart phones, and PDAs and they are manufactured by companies like Nokia, Blackberry, Motorola, and Intel. They will gain their profits through the sale of the terminal equipment. Nokia, the world’s top handset maker, expects to start selling cell phones using the WiMAX technology in 2008.

THE WiMAX BUSINESS MODEL

The biggest challenges to deploying WiMAX-based services are business related. Carriers need financial capability to implement infrastructure. Each operator has to carefully identify its own requirements, dictated by the type of services offered, the market segments targeted, the spectrum available, and the topography of the coverage area. There is no single solution that works for all, and operators need to make key choices about the management and core networks as they plan for their WiMAX networks.

An accurate business case analysis must take into account a wide variety of variables such as demographics, services, frequency band alternatives, capital expense items, operating expense items, and CPE equipment. The WiMAX business model can be looked from several perspectives. These include the equipment vendors, service providers and application providers, and customers. WiMAX will have a larger impact long term than we have seen from cellular phones in the past two decades. Initial rollouts of WiMAX will begin mostly by competitive local phone service carriers and rural Internet service providers. Larger carriers will utilize fixed WiMAX to deliver services to residential customers many of whom are in underserved markets. WiMAX adoption in these underserved markets will be high due to lack of availability of high-speed data access. These deployments will generate capital to be reinvested for future deployments. Larger customer base will begin driving both the cost of carrier and customer equipment down. As the economy of scale makes deployment less expensive, mobile platforms will begin to appear. This development will be spread between high population centers and the rural markets that already have fixed platforms deployed. Fixed platform will act as a springboard for mobile deployment. Then interconnections will begin to form between rural markets and metropolitan markets as carriers from cooperative agreements to share network resources. The economy of scale will increase exponentially at this point and we will notice a negative impact on traditional cellular, Internet, and voice services. Once the implementation of initial hot underserved rural markets and high-density metro areas is completed, springboard deployments will quickly take WiMAX coverage to the level of coverage offered by traditional wireless today. This process will move much faster than the deployment of cellular networks and devices for the following key reasons:

• Manufacturing process for WiMAX devices will be quite similar to that of wireless devices and mostly the changes will be in components and software.
• Readiness of the current wireless fixed and mobile market and waiting on new technology.
• As carriers built out wireless networks, most of the questions in this field have been answered and can now be applied to the development of a mirror network that provides WiMAX access.

NETWORK DIMENSIONING AND DESIGN

Designing, deploying, and managing any wireless cellular system requires clear objectives to be identified from the outset. These includes definition of the footprint coverage, the estimated number of users, the traffic load distribution, the penetration and growth rate, and internetwork access and roaming. Mobile WiMAX, which will be deployed like 2G and 3G cellular networks, supports fractional frequency. Fractional frequency reuse takes advantage of the fact that mobile WiMAX user transmit on subchannels and does not occupy an entire channel such as in 3G. The objective of the radio network dimensioning and design activity is to estimate the number of sites required to provide coverage and capacity for the targeted service areas and subscriber forecast. This process is based on many assumption such as uniform distribution of subscribers, homogenous morphology, and ideal site location. The main inputs required for network dimensioning are site equipment-specific parameters, marketing-specific parameters, and licenses regulation and propagation models. Figure 1 shows the flow chart of activities performed in network design and planning, starting from data collection of marketing and design requirement input and achieving the business model to provide a nominal site plan using a network simulation software.

 

Figure 1: The cell planning process.

Mobile WiMAX is designed to complement existing 2G/3G access technologies with an “Always Best Connected” experience with voice and data connections. There is a large range of possible scenarios for the deployment of mobile WiMAX, but main four categories are

• Fixed and mobile operator with enhanced data for GSM evolution (EDGE)/3G who uses mobile WiMAX as a complementary extension for data services
• Mobile only operator with EDGE/3G who uses mobile WiMAX as a complementary extension for data services
• Fixed operator who uses mobile WiMAX to compete with 3G operators for data and voice services
• New entrant who uses mobile WiMAX to move into mobile market—threat to incumbent mobile operator.

WiMAX operates in a mixture of licensed and unlicensed bands. The unlicensed bands are typically the 2.4- and 5.8-GHz bands. Licensed spectrum provides operators control over the usage of the band, allowing them to build a high-quality network. The unlicensed band, on the other hand, allows independence to provide backhaul services for hotspots. Typical area licensed WiMAX spectrum allocations are

• Lower 700 MHz (US) with 2 × 6 MHz channels
• 2.5 GHz Multichannel Multipoint Distribution Service with 15.5 MHz in US and 72 MHz in Canada
• 3.5 GHz Wireless Local Loop with 2 × 2 MHz channel blocks
• 5.8 GHz UNI (license exempt) with 80 MHz allocation

WiMAX access networks are often deployed in point-to-multipoint cellular fashion where a single BS provides wireless coverage to a set of end users stations within the coverage area. The technology behind WiMAX has been optimized to provide both large coverage distances of up to 30 km under line-of-sight (LOS) situations and typical cell range of up to 8 km under NLOS. In an NLOS, a signal reaches the receiver through reflections, scattering, and diffractions. The signals arriving at the receiver consists of many components from direct and indirect paths with different delay spreads, attenuation, polarizations, and stability relative to the direct path. WiMAX technology solves or mitigates the problem resulting from NLOS conditions by using OFDMA, Subchannelization, directional antennas, transceiver diversity, adaptive modulation, error correction, and power control. The NLOS technology also reduces installation expenses by making the under-the-eaves customer premise equipment (CPE) installation a reality and easing the difficulty of locating adequate CPE mounting locations.

Both LOS and NLOS coverage conditions are governed by propagation characteristics of their environment, radio link budget, and path loss. In both the cases, relays help to extend the range of the BS footprint coverage allowing for a cost-efficient deployment and service.