| Wireless telecommunications, that is, | | | | completed in a conventional manner. |
| telecommunications through the medium of radio | | | | In the manner described, a complete metropolitan or |
| waves, is rapidly emerging as the dominant force in | | | | rural telephone system can be set up and operated in |
| development of infrastructure in emerging economies. | | | | a manner transparent to the users. No wires are |
| The use of radio for mobile services, microwave links, | | | | needed, no access to public ways is required, and all |
| cellular telephone and broadcasting is well known and | | | | problems of theft and security of plant are avoided. |
| fairly widely deployed. Only recently coming on the | | | | Lacking exterior plant, reliability is greatly enhanced, as |
| scene are broadband radio services that not only | | | | well designed WLL facilities do not significantly suffer |
| provide the previously familiar wired services like | | | | from weather damage, vandalism, and accidents. |
| telephone, but go beyond to high speed data and digital | | | | Most important, because the WLL system has much |
| television access. Released from the bandwidth | | | | better bandwidth than traditional telephone systems, |
| constraints, deployment costs, and security concerns | | | | superior customer service features and quality can be |
| of copper wires wireless digital services can provide | | | | provided. WLL systems support high quality data |
| public services not even imagined a few years ago. | | | | transmission, signaling services, and all the most |
| Furthermore, the rate of adoption of these services | | | | advanced customer service features. |
| even as submarket segments in many industrialized | | | | The infrastructure design of a WLL system typically |
| economies has been sufficient to drive technological | | | | uses an advanced transmission technology such as |
| development and device pricing to the point of | | | | CDMA which permits support of large subscriber |
| affordability in less developed economies. Indeed, the | | | | bases through orderly expansion of the base station |
| deployment cost of wireless technologies is now well | | | | clusters. Such systems can support a mixture of rural |
| below that of conventional copper wire systems. | | | | and urban coverage, permitting modern telephone |
| From a technical standpoint, three wireless | | | | services to be economically extended to less |
| telecommunications opportunities exemplify the trend. | | | | advantaged population groups. Services like public |
| Wireless local loop, otherwise known as "WLL" is a | | | | payphone can also be supported. |
| direct stand-in for the familiar telephone line to the | | | | High-speed data is becoming an important part of the |
| home or business. High speed data transmission called | | | | modern business and personal lifestyle. Until the advent |
| Wireless Digital Data or "WDD" permits business and | | | | of Wireless Digital Data there was no economical |
| Internet data connectivity at rates unavailable over | | | | method available for the delivery of megabyte |
| telephone lines. Multichannel digital television distribution, | | | | datastreams. However, the huge data demands of |
| frequently known as "MMDS" allows a direct path to | | | | modern business, as well as the personal and business |
| home television receivers with dozens of program | | | | adoption of the Internet, have made such delivery |
| choices. | | | | crucial. |
| An added feature of these technologies is that a | | | | WDD is a wireless network technology that can be |
| properly designed network, with adequate frequency | | | | implemented in several forms. A typical configuration |
| spectrum, can often support implementations of all | | | | consists of broadband data transmitters located at |
| modes simultaneously. In fact, the most cost effective | | | | strategic sites to transmit broadband data streams to |
| approach to making these advanced services | | | | antennas located at the sites of primary users in a |
| available in developing markets will be to share digital | | | | market area. Receiving facilities of less bandwidth, |
| bandwidth to the greatest possible extent. This has | | | | WLL, or telephone access are established to permit a |
| been recognized recently by the United States Federal | | | | return path to complete a two-way data connection. |
| Communications Commission, which is authorizing | | | | Typically, more economical low bandwidth connections |
| spectrum with no content or use restrictions save | | | | are feasible for one half of the WDD connection, |
| those necessary to protect other services from direct | | | | although full broadband connectivity can be supplied to |
| frequency interference. | | | | users desiring it. |
| All of these services best operate over frequencies in | | | | The WDD network is connected to its own internal |
| the area of 2000 to 3000 megahertz. An allocation of | | | | computer servers and routers which determine the |
| 200 megahertz of this spectrum permits effective | | | | flow of customer data and interconnection with |
| development of systems that can deliver maximum | | | | external satellite, microwave, or fiber optic high speed |
| services at minimum initial cost. Many already | | | | data backbone networks. |
| developed low cost consumer hardware devices are | | | | Multichannel wireless digital television or MMDS is a |
| configured to operate from 2500 to 2700 megahertz, | | | | technology that permits the simultaneous distribution of |
| a frequency range that avoids conflict with satellite | | | | dozens of television programs to subscribers. Using |
| signals worldwide. In addition, additional spectrum is | | | | strategically located, relatively low power, transmitters |
| typically needed on a limited basis to support | | | | to broadcast multichannel signals, MMDS can "blanket" |
| microwave interconnect links between infrastructure | | | | a region with reception capability that would not be |
| transmitting nodes. This should be readily available, | | | | physically or economically practical with conventional |
| based upon local design needs. | | | | wired cable television. |
| Wireless local loop is analogous with local telephone | | | | The subscriber receive equipment is low cost, easily |
| service, but much more capable. A WLL system | | | | installed, and quite maintenance free. It can be |
| serves a local area by deploying a multiplicity of | | | | programmed to respond to only authorized channels, |
| multichannel transmit/receive base stations which are | | | | making opportunities for the same network to support |
| within line-of-site of the intended customers. Each | | | | entertainment, private conferencing, education, and |
| customer is equipped with a mini-station of low power, | | | | government channels without conflict and in full |
| into which the telephone (or PBX) is connected. When | | | | security. Moreover, the system technology will be |
| calls are made from the telephone, it signals the base | | | | capable of supporting high quality "high definition TV" in |
| station for a connection, which is subsequently | | | | the future. |
| established through a switch center, exactly as in | | | | MMDS systems can also support a mix of analog and |
| conventional telephony. An incoming call is identified at | | | | digital transmission, which provides for a migration path |
| the switch center and routed to the base station | | | | from an initial "conventional" analog TV offering to a |
| assigned to serve the telephone being called. The | | | | "state-of-art" full digital facility in response to subscriber |
| wireless connection is then made, and the call | | | | demand. |