Feeding an IRB enables a point-to-multipoint service, creating a central pipe that serves many customers. The uplink connection may be terminated at the building’s point of demarcation, enabling service over telephone copper wires.

Access for Wireless Operators

For wireless CLECs, LMDS is one of the leading technologies, enabling quick market penetration. CLECs’ initial target market is the corporate sector, which may require symmetrical characteristics of traffic. However, CLECs can use their LMDS capacity to provide high-speed Internet services to residential buildings and complexes as well. Through an installed antenna and terminal at the building top, they may connect via a dedicated wire to the IRB network by dropping a single fiber or Category 5 (CAT5) to the telco room at the basement. This enables a high-resolution service from a single connection at the point of demarcation (see Figure 3).

3. CLEC Implementation with LMDS

Using the existing legacy copper wire with DSL transport techniques for implementing the IRB provides CLECs with a wireless copper architecture that represents a win-win solution. This configuration converts the building into a business unit, thus making it broadband-ready for service. This type of architecture is an excellent business case for cellular operators who are looking to extend their business activities. Using the cellular base stations as an infrastructure for deploying the LMDS service drastically reduces the required investments.

For wireless VSAT operators, the story is the same. However, the traffic is not symmetrical, and an additional uplink connection does not necessarily exist. In the latter case, a wireline uplink mechanism is needed, making this application problematic.

Access for Wireline Operators

For ILECs, PTTs, and CLECs, asymmetric digital subscriber line (ADSL) services in mass numbers to MDUs (where the digital subscriber line access multiplexer [DSLAM] is located in the CO) seems impractical and overly expensive from a technological point of view. Extending the service to the building’s point of demarcation is far more robust and economical.

Implementation is accomplished with the installation of one or more xDSL lines to the IRB. With this configuration, only the nonvoice, high-quality copper pairs can be selected to feed the IRB, as the bundle from the CO usually has more than enough extra copper pairs. Nevertheless, the xDSL connection can be installed over four wires rather than the usual two, thus improving transport capabilities. In the case of higher-bandwidth requirement, an additional xDSL connection can be installed.

Again, feeding an IRB enables a point-to-multipoint service, creating a central pipe that serves many customers. When the IRB is implemented through the legacy copper wires, the building is broadband-ready for business.

An ISP or a CLEC can adopt this application by leasing the unbundled copper from the local telephone company at the CO. Working with IRBs reduces the overall cost, as only a few copper wires are required for leasing; distribution is done at the IRB. In the classical ADSL solution, leased copper is needed per customer. Moreover, with the IRB, the single pipe with the service is multiplied now by the number of subscribers, which brings it to an economical solution.

Access for FITL and Double Copper Tier

For ILECs, PTTs, and IXCs, fiber-in-the-loop is the most advanced architecture for neighborhood services. Fiber can reach the curb, the street cabinet, or the building basement. In this case, the IRB is connected with an uplink, which confirms the service carried by the fiber (either ATM, packet over synchronous optical network [SONET], future passive optical network [PON], etc.) With this configuration, the provider can have a very-high-speed service, aggregating the IRB’s subscribers. Again, the building is broadband-ready for service.

Of course, the simplest case is when the fiber reaches the building’s telco room. However, when fiber feeds the street cabinet or the DLC, copper wiring is needed to distribute the service to the IRBs (see Figure 4). In this case, high-quality, nonvoice copper wire can be used to extend the accessibility to the building, creating a double copper tier architecture. The first tier goes from the street cabinet to the building’s telco room, using only the nonvoice, high-quality, extra copper pairs, thus feeding the IRB. The second tier is inside the IRB where the service is implemented by using DSL techniques.

Figure 4. Implementation with Fiber and Double Copper Tier