PERFORMANCE ANALYSIS OF QAM MODULATIONS APPLIED TO THE LINC TRANSMITTER

被引:32
作者
CASADEVALL, FJ
VALDOVINOS, A
机构
[1] Department of Signal Theory and Communications, Universidad Polit\'ecnica de Catalunya, Barcelona 08080
关键词
Amplitude modulation - Performance - Radio transmitters - Signal to noise ratio;
D O I
10.1109/25.260773
中图分类号
TM [电工技术]; TN [电子技术、通信技术];
学科分类号
0808 ; 0809 ;
摘要
Future mobile radiocommunications systems will use linear modulations because they show a higher spectrum efficiency than classical FM modulations. Furthermore, in order to use these modulations in hand-portable equipment, power efficiency is also requested for the power amplifiers. To obtain both power and spectrum efficiency, a LINC(1) transmitter can be considered. In this paper, we present an analysis-of the effect of different types of imbalances between the parallel signal paths in a LINC transmitter. The system degradations are described in terms of adjacent channel rejection, (U-R) Classical raised cosine (Nyquist filtered) 4, 16, and 64 QAM modulation patterns are taken into account, and in all cases, upper bounds for adjacent channel rejection as function of the gain and phase imbalances as well as of the guard band between adjacent channels are presented. Moreover, the impact of these imbalances in the system performance, characterized by means of the signal-to-noise ratio (SNR) increment needed to maintain a fixed error rate, is also considered. The results show that gain and phase imbalance between both RF paths could be a serious limitation for the LINC transmitter performance.
引用
收藏
页码:399 / 406
页数:8
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