|Issue:||Latin America III 2000|
|Topic:||Virtual City Models for Broadband Wireless Networks|
|Title:||Director of Product Marketing|
Sustained by the ever-growing pressure for increased speed and bandwidth, broadband wireless telecommunication technologies are promised to a bright future. They provide economical solutions for fast and scalable network deployment, and solve the “last mile connection” problem. However these technologies also give rise to new requirements.
Because broadband wireless networks rely on line-of-sight connections, the efficiency of their deployment is dependent on highly accurate geographic information. Sending technicians to roam the streets or climb rooftops to check line-of-sight connections between antennae is increasingly a thing of the past. Nowadays engineers simulate the propagation of radio signals using virtual city models that are computed from 3D databases containing buildings, bridges and vegetation in addition to the underlying terrain. For telecommunication companies relying on 3D databases, the issues at stake range from increased efficiency to cost-effectiveness. Engineers scoping wireless networks such as LMDS need to know the size and shape of obstacles to perform line-of-sight analysis and optimal position antennae. Accurate elevation information enables them to check for interference between radio beams and obstacles such as vegetation and rooftops. Planners working on microcell networks have other priorities in mind: they have to dimension their network to face ever-growing traffic, and must optimise coverage in dense urban areas. In order to deploy cellular networks with pinpoint accuracy, they need to compute signal propagation along the streets very precisely, this is only possible if exact building contours are available. In both cases, engineers are increasingly relying on highly accurate and up-to-date geographic databases. Such databases are available from specialised companies such as Istar. Computed from especially commissioned aerial stereo-photographs, they provide precise building information, at 0.50cm resolution, for extended urban areas, from downtown suburbs to industrial zones. Each integrated database is computed from multiple views giving consistent restitution of built-up areas, building details, vegetation and bridges. The databases provide ground surface elevation information as well as the information needed to represent the outline and elevation of built-up structures. Aside from base station and antenna positioning, integrated 3D geographic databases can benefit telecommunications companies during each phase of business development. By merging the geographic database with business addresses and demographic data, a variety of task specific tools can be built that allow one to visualise significant data from a new perspective. Network scoping and cost assessment can be depicted, as can network deployment and maintenance. Special mapping can be developed for marketing and sales purposes and for commercial applications – to lease sites where antennae are to be located, for example, or to instantly display a customers building coverage. Conclusion Telecommunications companies thinking of purchasing quality 3D databases should look at such an acquisition as an investment. These databases can provide a substantial return on the investment involved by considerably reducing network deployment costs. Computer simulation of signal propagation, using the 3D databases, eliminates costly field measurements and facilitates an iterative process that, by the accurate positioning of fewer antennae, often saves the expense for additional equipment.