N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 9 - Wireless Systems and Technologies                                                                                 Slide 40 of 80                                                                                                    ________________

Basic LMDS Network Configuration

                                                LMDS Cell 

                                                Cellular Subscriber Coverage

                                                Cellular Network Capacity

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Basic LMDS network configuration consists of multiple  LMDS cells. Repeaters are used to extend the signal to the cells.

LMDS Cell - A radio cell is defined as a continuous geographic area in which the LMDS network will provide broadband services according to specified quality and performance criteria. A radio cell structure (in square kilometers) is derived by combining a geographical area (characterized by local topology, demography and meteorology) and radio network design. The major components of a radio cell design, to provide broadband access, are base station, micro-cell radio repeaters and customer premises equipment. Several base stations could be covering a single cell. Maximum range for the micro-cells is typically 0.1 to 1.0 Km whereas a cell ranges between 1.5 to 2.5 Kms.

Cellular Subscriber Coverage - Subscriber coverage relies on line-of-site conditions to ensure proper operations. Radio transmission at G Hz range is blocked by buildings, vegetation and terrain intercepting the radio path between the base station and the CPEs. Individual CPE line-of-site conditions are dependent on the radio path for a given base station antenna height. Radio path elevations can be compensated by increasing the CPE antenna heights as the customer distance increases from the base station. Normally base station heights range from 20 to 40 m; residential customer antenna heights up to 2-3 m above roof line; business customer antenna height 5 m above roof line.

Cellular Network Capacity - maximum available network capacity is determined by available spectrum bandwidth, spectrum re-use and spectral efficiency. No simple procedure exits for calculating the number of simultaneous users supported by the LMDS network.

In a large LMDS network multiple cells are inter-networked.