28 GHz Local Multipoint Distribution Service (LMDS): Strengths and Challenges

Abstract

Local Multipoint Distribution Service (LMDS) is a terrestrial point-to-multipoint radio service providing wireless broadband access to fixed networks. LMDS could be used to provide wireless access to services ranging from one-way video distribution and telephony to fully-interactive switched broadband multimedia applications. Multiple hub transmitters that communicate via point-to-multipoint radio links with subscribers at fixed locations throughout the service area are placed in a cellular-like layout. LMDS systems attempt to completely reuse the frequency band in each cell through the use of highly directional subscriber antennas and polarization reuse in adjacent cells. Proposed LMDS system architectures differ in terms of cell size, modulation, and hub antenna type. This paper describes the potential service offerings and technical characteristics of LMDS systems. Publicly available system design information was gathered from the FCC Negotiated Rulemaking Committee (NRMC) on co-frequency sharing in the 28 GHz band between LMDS and satellite services. This paper also describes some of the challenges that face LMDS such as a “fragile” propagation environment. The results of a propagation measurement campaign at 28 GHz in Brighton Beach, Brooklyn, to investigate the performance of Local Multipoint Distribution Service (LMDS) indicate that building blockage is a major limitation on the ability to cover a particular location. Strong signals were only received at locations where a line-of-sight path was available between the transmitter and receiver.