Partitioning of spreading sequences for increased minimum distance using CPFSK modulation

Author

Fulghum, Tracy L. ; Miller, Scott L.

Author_Institution

Ericsson Inc., Research Triangle Park, NC, USA

Volume

47

Issue

4

fYear

1999

fDate

4/1/1999 12:00:00 AM

Firstpage

493

Lastpage

497

Abstract

By using continuous-phase frequency shift keying (CPFSK) in a direct-sequence code-division multiple-access (DS-CDMA) system, and by partitioning the spreading sequence so that differing patterns of plus and minus chips are multiplied onto successive data bits, the net phase change will differ from bit to bit, giving an apparent variation in modulation index similar to multi-h CPFSK. This gives similar coding gain effects as multi-h CPFSK when maximum-likelihood sequence detection is used. Improved probability of error performance in terms of increased minimum distance has been demonstrated when the spreading sequence of a CDMA system is properly overlaid on outgoing data bits in the CPFSK modulation scheme. At the best modulation index observed, h=5/7, a computer search shows ~1.4-dB advantage over binary phase shift keying, and a ~0.6-dB advantage over the best fixed-h CPFSK

Keywords

code division multiple access; continuous phase modulation; error statistics; frequency shift keying; m-sequences; maximum likelihood detection; search problems; spread spectrum communication; CPFSK modulation; DS-CDMA system; Gold sequences; binary phase shift keying; coding gain; computer search; continuous-phase frequency shift keying; direct-sequence code-division multiple-access; error probability performance; increased minimum distance; m-sequences; maximum-likelihood sequence detection; modulation index variation; multi-h CPFSK; net phase change; pseudorandom sequences; spreading sequences partitioning; successive data bits; Binary phase shift keying; Computer errors; Continuous phase modulation; Demodulation; Frequency shift keying; Maximum likelihood detection; Modulation coding; Multiaccess communication; Multiple access interference; Spread spectrum communication;

fLanguage

English

Journal_Title

Communications, IEEE Transactions on

Publisher

ieee

ISSN

0090-6778

Type

jour

DOI

10.1109/26.764919

Filename

764919