 | Issue: | Asia-Pacific I 2001 |
| Article no.: | 4 | |
| Topic: | The Wireless Last Mile | |
| Author: | Jim Edson | |
| Title: | Vice-President | |
| Organisation: | Worldwide Sales, Littlefeet Inc., USA | |
| PDF size: | 20KB |
About author
Not available
Article abstract
The first decade of the new millennium promises a continuation of the tremen-dous progress in the telecom industry. Advances in optical networking, multi-service platforms, and wireless are not only increasing the ability of operators to deliver new services, but also lowering the cost to do so. This poses an interesting question: Are we approaching the point where basic, economical telecommunications service can reach the masses of the world?
Full Article
Today, the definition of “basic” telecommunications is not just the ability to make and receive voice calls and be connected to a public network. Basic telephony now includes the ability to connect to the internet at a reasonable speed and at reasonable cost. In the US, where wireline service is available to virtually all of the population, there is already an on-going debate among regulators, operators, and special interest groups on how to close the “digital divide.” That is, how do you bring the promise of the Internet, and the benefits of the “Information Age”, to everyone? Those without access lag behind in terms of economic advancement. This will also be true of a large part of the world population today if basic access continues to be unavailable. Technical advances have made the economics favourable for implementation of core networks to support a variety of services. However, access technologies used for the so-called “last mile” access have lagged behind. Last mile access is how the end user is physically connected to the network providing the services. How will this be achieved? Most of the population of the world is not wired with cable or copper. The cost to provide the wired last mile access is prohibitive. The alternative to wired is of course wireless which offers a solution that has a low cost per customer covered and lowered maintenance costs, can be quickly deployed, and is highly scaleable. The past decade was marked by tremendous growth of terrestrial based wireless systems that introduced mobility to a population already served by fixed wireline. Wireless should be the choice to deliver basic telephony to the masses. Last mile wireless access will utilise a variety of wireless technologies, some standardised, others proprietary. The key considerations in determining the type of the wireless access system will be solutions which; require the least cabling of buildings, hence the lowest cost to cover many subscribers, provide the highest quality of coverage (since the goal is to provide reliable primary access), and provide for the widest range of deployment options. This effort of providing wireless access for the “last mile” will not follow the same patterns as the traditional mobile wireless carrier. New wireless operators face a host of issues building and maintaining networks; providing ubiquitous high quality coverage; managing capacity planning; finding suitable sites for equipment; complying with health and safety regulations, and managing the lifecycle costs of the network. Service providers must employ different thinking to address these challenges. One of the biggest challenges will be zoning. The launch of new wireless networks (third, fourth and even fifth operators in many regions), means increased competition for infrastructure equipment sites, towers and antennas. Many existing towers can no longer accommodate additional operators. Those that can often yield sub-optimal antenna heights and sub-optimal performance. Requests for new tower locations receive increasingly tough scrutiny, extended approval cycle times, and often rejection from local authorities. The process adds expense to an already expensive solution. Recent press articles about perceived health risks from RF radiation and commu-nity hostility toward towers dictate a more community-friendly strategy by operators. Aside from tower issues, for operators seeking to provide the last mile connectivity, there is another big issue related to zoning: working with building owners to implement adequate in-building coverage. Many mobile users have come to expect poor in-building coverage, but if wireless becomes a primary access technology, then the signal level must be guaranteed. The new challenges faced by wireless operators, including the need to gain market share and guarantee customer loyalty by enhancing service levels, dictates that operators re-think how networks are designed and constructed. For most of the brief history of cellular communications, economics dictated that networks be built with as few sites as possible to minimise capital and operating expenses. This resulted in relatively good basic coverage, which was later supple-mented with additional RF carriers to add incremental capacity. Unfortunately, this philosophy gen-erally resulted in costly sites due to tower heights required to gain an optimal footprint, sub-optimal spectrum utilisation, and extensive network planning. Despite high RF output, networks suffered from non-uniform signal quality that resulted in numerous coverage holes and less than adequate in-building coverage. Yesterday’s networks are ill equipped for tomorrow’s requirements and end-user expectations. Operators must design networks capable of supporting intensive data usage, with very good in-building coverage and few, if any, coverage holes. Fortunately, today there are several access technologies available to help operators overcome their network challenges: micro (or, compact) base stations, smart antennas, repeaters and other distributed RF systems. The key for network planners will be to optimise the mix of these different solutions to meet the needs of the wireless operator. These new network solutions are generally lower power, lower profile, and lower cost. Simply put, they have lower impact on the environment in which they are implemented, and in some cases are totally stealth. Increasingly, operators are using these solutions in designing networks with access points much closer to the subscriber instead of atop towers distant from the user. This also allows for the more uniform signal which is required to guarantee signal level. Although more sites may have to be deployed, the basic hardware costs of many of these solutions and their total site costs, are less than traditional networks based exclusively on macro-cells. Sites with smaller footprints allow for more control over the cell edge reducing interference and, in turn, allowing for increased frequency reuse. Many operators have limited spectrum. Consequently, better frequency reuse is essential to support growth. Another design and operating benefit is the suitability of low-profile equipment for a variety of deployment scenarios that traditional infrastructure cannot handle efficiently or cost-effectively. Examples include infrastructure instal-lations on utility poles, billboards, highway signs, building walls, or rooftops where structural improvements would not be possible for traditional solutions. Increased deployment altern-atives vastly expand the range of feasible sites and offer the operator more flexibility. Site acquisition times can be significantly reduced, zoning approvals can be expedited, and monthly lease costs can be reduced. In the end, subscribers benefit from networks that can provide more ubiquitous and homogeneous coverage, higher service quality with fewer dropped calls, improved in-building coverage, and high speed/high quality data service. The operator, in turn, benefits from improved network performance, increased usage from both data and voice services, and increased customer loyalty. A variety of companies offer competitive products with some of the features operators need to overcome the challenges they face. Most of the major infrastructure vendors (Nokia, Motorola, Siemens, etc) manufacture micro-BTSs used to improve frequency reuse. Arraycom and Metawave are leading the category of “smart” antenna products that offer additional capacity. Similarly, Transcept and LGC Wireless offer distributed antennas systems, while Mikom-Allen Telecom and CI Wireless offer repeaters. Both of these categories can help provide coverage in hard to reach areas. A new category of wireless infrastructure products called SPICE has been developed by Littlefeet Inc. SPICE is a low-impact infrastructure solution that expands deployment options, reduces time to market and enhances network performance. SPICE combines the features of micro base stations, repeaters and intelligent modems. Conclusion SPICE’s clustered architecture enables operators to benefit from macro-diversity. Macro-diversity gain is achieved by simulcasting to the subscriber’s mobile through a cluster of SPICE units in any given cell area, which results in substantial signal quality increase and deep fade reduction. The main components of the SPICE system are shown in the figure above. A bSPICE unit is co-located with a BTS and wirelessly transmits the signal from the BTS to a group of cSPICE units. The cSPICE units, in turn, re-broadcast this signal to mobile subscribers. One bSPICE and a group of cSPICE units cover a typical cell area.
