Technical description of broadband LMDS access

There are three main types of broadband fixed wireless access technology, namely, the multiple-point distribution Service (MMDS), the direct broadcast Satellite System (DBS) and the local Multicast Distribution Service (LMDS) which is in the experimental stage. The first two are already well known, and LMDs is just emerging, and has recently become a popular broadband wireless access technology. LMDs is a kind of microwave broadband service, working in the 28GHz band, in the near distance two-way transmission of voice, data and images and other information. LMDS uses a honeycomb-like service area structure to divide a region that needs to be serviced into a number of services, with a base station in each serving area, and a base station device that communicates with the client side of the site via a point-to-point wireless link. Each service area covers a few kilometres to more than 10 kilometres and can overlap each other.

The three most basic elements of LMDS are: Base station, client device and network management system. The base station is a central hubs that handles all communication between cellular users, including indoor and outdoor equipment. The indoor equipment provides the interface for the user to connect to the wired or wireless backbone network, the outdoor equipment includes the transmitter and the receiver, usually installed on the tower or on the roof. These devices are responsible for collecting and delivering all communications to and from a hive or sector. The client device is functionally similar to the base station device, except that the structure changes slightly. On the client side, the transmitter, receiver and antenna are generally merged into a highly directional device. The network Management System (NMS) is responsible for managing the services provided by wired and wireless networks. The ideal network management system should be able to provide end-to-end management for the entire network, including backbone networks and clients.