Some design issues in local multipoint distribution systems

Local multipoint distribution systems (LMDS) refer to millimeter-wave point-to-multipoint radio networks which were originally intended for digital TV broadcasting, video-on-demand (VoD), and similar consumer services with limited interactivity. It was later recognized that LMDS systems have a strong potential to supply broadband services to both homes and businesses, and the interest gradually shifted toward these applications. In this paper, we first give an overview of LMDS systems, and describe the technical specifications elaborated by the Digital Video Broadcasting (DVB) project and the Digital AudioVisual Council (DAVIC) which form the technical basis of most LMDS system developments to date. Next, we discuss frequency allocation, frequency planning, and LMDS system design to transport symmetric or asymmetric traffic. Then, we address a number of basic design issues which include antenna sectorization and frequency reuse patterns, discuss the use of higher-level modulations to increase cell capacity and compare different multiple access techniques.