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Performance of M ‐QAM modulations for indoor radio communications with combined diversity and equalization techniques
Author(s) -
Casadevall Fernando J.,
Valdovinos Antonio
Publication year - 1992
Publication title -
international journal of digital and analog communication systems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.344
H-Index - 49
eISSN - 1099-1131
pISSN - 1047-9627
DOI - 10.1002/dac.4510050206
Subject(s) - fading , multipath propagation , computer science , channel (broadcasting) , equalization (audio) , antenna diversity , diversity combining , communications system , qam , digital radio , diversity scheme , electronic engineering , telecommunications , quadrature amplitude modulation , bit error rate , wireless , engineering
Digital indoor radio communications systems have become an attractive proposal as they could provide the user high quality voice and low rate data services with total mobility. However, indoor communications are affected by multipath propagation that restricts their application imposing an upper limit on the system data rate. To overcome this drawback diversity and channel equalization could be considered. In this paper the performances of 4, 16 and 64‐QAM modulations in a radio communications indoor environment are presented. The results show that a system without protection has very limited performance. Diversity techniques are efficient when the radio channel can be assumed to be non‐selective. For systems operating in selective fading channels joint equalization and diversity techniques are necessary to fight the degrading effect introduced by the channel. Moreover, if correlation between the two diversity channels is taken into account, the system performances remain almost unchanged, assuming that the correlation coefficient between the two diversity branches is lower than 0.6 to 0.7 approximately.