Broadband Radio Access to Homes and Businesses: MMDS and LMDS
This paper gives an overview of digital microwave multipoint distribution systems (MMDS) and local multipoint distribution systems (LMDS) originally developed for digital TV broadcasting and later extended to offer interactive services for homes and businesses. We first describe the specification work carried out by the Digital Video Broadcasting (DVB) project and the Digital Audio Visual Council (DAVIC) which forms the technical basis of these systems. Next, after presenting initial frequency allocations particularly in Europe and North America, we discuss the potential of MMDS and LMDS to offer broadband services to homes as well as to small- and medium-size businesses. We also discuss the major technical issues related to the design of these systems, frequency planning and reuse patterns, as well as future technical evolutions to make them more efficient in terms of performance, capacity, and the service offered. This discussion includes the use of higher-level modulations, multiple access techniques such as code-division multiple access (CDMA) and orthogonal frequency-division multiple access (OFDMA), and of adaptive arrays for electronic beamforming.