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Modem Design Issues in LMDS Systems



J E. Haakegaard


During the last 2-3 years, there has been considerable activity aimed towards deploying broadband wireless access systems. The US Local Multipoint Distribution Services (LMDS) auctions in February-March 1998 of 1.3 GHz of spectrum between 27.5 GHz and 31.3 GHz triggered efforts to develop system solutions and standards, whose objective is to render LMDS systems competitive to other broadband, and primarily wireline, technologies. The modem design must be matched to the channel characteristics of LMDS systems, which are very different from those of coax and even lower frequency wireless communications systems. In addition, the cost factor is a key issue to face the competition from other technologies. A modem design meeting these two constraints is described in this paper, together with an analysis of the main impairments characterizing the LMDS channel. The modem includes fully rotational invariant trellis coded modulation (TCM), amplitude phase modulation (APM), equalization and predistortion.
IEEE Communications Magazine


co-channel interference, Ka-band channel, LMDS, modem design, non-linear HPA, pragmatic, TCM


Haakegaard, J. (1999), Modem Design Issues in LMDS Systems, IEEE Communications Magazine (Accessed April 18, 2024)
Created May 8, 1999, Updated February 19, 2017