Aπ/4 crossed cascaded adaptive array for mobile satellite communications

✍ Scribed by Derbala, Mohammed A. ;Al-Hussaini, Emad K.

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 155 KB
• Volume: 17
• Category: Article
• ISSN: 0737-2884
• DOI: 10.1002/(sici)1099-1247(199909/10)17:5<325::aid-sat642>3.0.co;2-q

✦ Synopsis

Adaptive arrays in mobile communications based on any arbitrary performance criteria have many problems in tracking the desired signal at di!erent interference angles relative to the desired one. To use the adaptive arrays e$ciently in mobile communications, we need a system which is independent of interference angles. In this paper a system nominated as /4 crossed cascaded adaptive array ( /4 CC) based on (for example) the well-known constant modulus algorithm (CMA) is suggested. It is a four elements adaptive array, each two elements are controlled by the CMA and they are crossed by 453 angle in the vertical plane. The proposed system is examined by computer simulation and compared with the conventional system. It is found that the conventional two elements array is su!ering from the capture problem and its performance is degraded at certain interference angles e.g. 25, 50, 553, 2 . When the interference power is equal to the desired signal, the proposed system outperforms the conventional one. Therefore, the suggested system is more suitable in mobile communications which employs CM modulation techniques such as FM, QPSK, GMSK , 2 .

In this article the analysis of the CMA and the proposed system are considered in detail. The system under consideration can be used also for all other adaptive arrays employing LMS, PI, and Applebaum, etc.