in black and white
Main menu
Home About us Share a book
Biology Business Chemistry Computers Culture Economics Fiction Games Guide History Management Mathematical Medicine Mental Fitnes Physics Psychology Scince Sport Technics

The business of wimax - Pareek D.

Pareek D. The business of wimax - Wiley publishing , 2006. - 330 p.
ISBN-10 0-470-02691
Download (direct link): thebusinessof2006.pdf
Previous << 1 .. 26 27 28 29 30 31 < 32 > 33 34 35 36 37 38 .. 107 >> Next

Infrastructure Placement
Infrastructure location refers to the physical location of infrastructure elements. Infrastructure placement can be an issue for both licensed and licence-exempt solutions. However, infrastructure placement presents some special considerations for licence-exempt solutions. Service providers are quickly deploying solutions in specific areas to stake out territories with high subscriber density and spectrum efficiency. Such areas include higher ground, densely populated or population growth areas, and areas with a less crowded RF spectrum. In addition, the physical structure that houses or supports the base station must be RF-compatible. A metal farm silo, for example, may distort signals, or a tree swaying in the wind may change signal strength.
Addressing issues with infrastructure placement
Infrastructure placement establishes the foundation for the service provider’s network. When choosing a location for deployment, a service provider must ensure that it can obtain access to the site at all times, that the building or location does not contain physical material that is not RF-friendly and that the infrastructure provides protection against weather-related elements, such as wind and lightning. Obstacles such as trees and buildings frequently block signal paths in urban areas and
some rural areas. NLOS performance is greatly improved with 802.162004 due to its improved resistance to multipath interference. Even with no direct LOS between the base station and the subscriber station, signals can be received after they reflect off buildings or other obstructions. Factors such as these make a preliminary site survey indispensable. Infrastructure placement provides a solid market advantage for incumbents. The cost and time involved in obtaining building permits, leases and roof space present significant barriers to those without an already established infrastructure.
Deployment Costs
The increased number of cell sites, as a result of using higher frequency bands, increases site acquisition/leasing and construction costs, regardless of the technology being deployed. The cost to acquire a site in North America can easily reach $25 000, plus ongoing lease costs, while an operator may have to spend up to $75 000 on construction costs to get the site up and running - assuming the operator starts from scratch. Further, the logistical challenges of getting enough sites to deploy a ubiquitous mobile network can pose a tremendous challenge, regardless of the cost factor.
That said, WiMAX will probably have a lower cost structure with respect to the core network, or the portion of the network that is ‘behind’ the base stations. Specifically, WiMAX uses an all-IP core which means it is scalable and can therefore support a higher level of user traffic for a given amount of network resources.
Additionally, WiMAX makes use of off-the-shelf routers vs a combination of circuit switches and other network components, which, although similar to off-the-shelf routers, have been specially customized for use in a cellular network. It is important to point out, however, that 3G is also transitioning to an all-IP core, at which point it will greatly reduce its own cost structure and achieve higher scalability than is possible today.
Unfinished Business
The 802.16e standard only addresses the PHY and MAC layers, leaving it to the WiMAX Forum to tackle issues such as call control, session management, security, the network architecture and roaming. To put
things in perspective, as the standard is currently written, each WiMAX base station is virtually oblivious of its surrounding base stations while the MAC layer only has placeholders for the messaging traffic associated with implementing a handover. As a consequence, the notion of seamless mobility does not exist while power management issues could result in reduced performance, in particular for users at the cell edge (25-35% of the network), where intercell interference would be most evident.
The WiMAX Forum created a network architecture working group in late 2004 to address some of these unresolved issues, but it is unrealistic to expect all of them to be solved, let alone tested and verified, in a few months. As it stands now, the first revision of the networking specification is scheduled to be completed by the end of the year. As an interim step, the WiMAX Forum is moving to first implement a portable solution which lacks some of the network intelligence required to support higher vehicular speeds (up to 120 km/h) and seamless handoffs.
In lieu of applications and services, such as voice, that require seamless handoffs and in the absence of widespread coverage, a portable broadband connection should more than adequately meet the needs of high-bandwidth data users.
WiMAX Chipset Availability
Another major uncertainty is the availability of chipsets. In addition to Intel and Fujitsu, several private companies are also promising very compelling .16e chipset solutions and they may, in fact, beat the larger silicon suppliers to the market. Regardless of who is first to market, it will be a challenge to have the silicon available for sampling any time soon. The mobile standard will not be finished until later in 2005 and the initial profiles have not been selected yet, meaning that, while some work can currently be done, the fine technical details cannot be implemented until after the standard is fully ratified. Equally important, the major semiconductor companies who are important to the success of WiMAX are not necessarily first-to-market suppliers of wireless chipsets (Wi-Fi and cellular technologies are two examples). Given some of the requirements for the mobile WiMAX solution, it could take more than one die spin to manufacture a chipset that supports the initial WiMAX profiles and does so with adequate performance (size, power requirements etc.).
Previous << 1 .. 26 27 28 29 30 31 < 32 > 33 34 35 36 37 38 .. 107 >> Next