PN code selection for synchronous CDMA

Details PN code selection for synchronous CDMA PN code selection for synchronous CDMA

1999-06-09

2004-04-20

Nguyen, Steven (Department: 2665)

Multiplex communications

Communication over free space

Having a plurality of contiguous regions served by...

C370S203000

Reexamination Certificate

active

06724741

ABSTRACT:

FIELD OF THE INVENTION
This patent application relates generally to digital radio telecommunications systems and, in particular, to synchronous Code Division Multiple Access (CDMA) telecommunications that employ pseudonoise (PN) spreading codes, such as Hadamard or Walsh codes.
BACKGROUND OF THE INVENTION
In synchronous CDMA systems the PN codeset that is typically used to differentiate users is the Walsh set. However, the Walsh codeset has poor spectral properties and, as a result, it is desirable to provide some randomization of the codeset. It is known in the art to scramble the Walsh code by generating another PN code, i.e., a “cover code”, of the same length as the Walsh code, and to then exclusive-OR (XOR) each code in the Walsh codeset with the cover code. However, this technique does not always provide the best improvement in the spectral properties of the Walsh codes used by the system.
General reference in this regard can be had to U.S. Pat. No. 5,751,761, entitled “System and Method for Orthogonal Spread Spectrum Sequence Generation in Variable Data Rate Systems”, by K. S. Gilhousen.
OBJECTS OF THE INVENTION
It is an object of this invention to provide an improved technique for providing PN spreading codes for use in a CDMA radio telecommunications system.
It is another object of this invention to improve the performance and reliability of synchronous CDMA systems.
It is a further object of this invention to improve the spectral properties of a PN codeset for use in channels of a synchronous CDMA telecommunications system.
SUMMARY OF THE INVENTION
The foregoing and other problems are overcome and the objects of the invention are realized by methods and apparatus in accordance with embodiments of this invention.
A method in accordance with the teachings of this invention improves the spectral properties of a PN codeset, such as a Hadamard PN codeset, for use in channels of a synchronous CDMA telecommunications system. The method comprises steps of (a) providing the PN codeset matrix; and (b) reordering the columns of the PN codeset matrix in accordance with a reordering pattern. The method may further include the step of inverting at least one codeword of the reordered PN codeset in accordance with an inversion pattern, and may further include the step of selecting PN codes to optimize a subset of channels to operate in an asynchronous manner.


REFERENCES:
patent: 5151919 (1992-09-01), Dent
patent: 5204876 (1993-04-01), Bruckert et al.
patent: 5329547 (1994-07-01), Ling
patent: 5418813 (1995-05-01), Schaffner et al.
patent: 5442625 (1995-08-01), Gitlin et al.
patent: 5515396 (1996-05-01), Dalekotzin
patent: 5548613 (1996-08-01), Kaku et al.
patent: 5659573 (1997-08-01), Bruckert et al.
patent: 5729124 (1998-03-01), Lu
patent: 5748668 (1998-05-01), Tomita et al.
patent: 5751761 (1998-05-01), Gilhousen
patent: 5757767 (1998-05-01), Zehavi
patent: 5805567 (1998-09-01), Ramesh
patent: 5805584 (1998-09-01), Kingston et al.
patent: 5825835 (1998-10-01), Kingston et al.
patent: 5851187 (1998-12-01), Thomas, III et al.
patent: 5864548 (1999-01-01), Liu
patent: 5936972 (1999-08-01), Meidan et al.
patent: 6091760 (2000-07-01), Giallorenzi et al.
patent: 6091761 (2000-07-01), Popovic
“On The Transmission Of Walsh Modulated Multiplex Signals”, Hubner H., Applications Of Walsh Functions, 1970 Proceedings, pp. 41-45.
“Analog And Digital Multiplexing By Means Of Walsh Functions”, Hubner, H., Applications Of Walsh Functions, 1970 Proceedings, pp. 238-247.
Multiplexing Of Telephone Signals By Walsh Functions, Davidson, I.A., Applications Of Walsh Functions, 1971 Proceedings, Apr. 13, 1971, pp. 177-179.
“Multiplex Systems Using Sums of Walsh Functions As Carriers”, Hubner, H., Applications Of Walsh Functions, 1971 Proceedings, Apr. 13, 1971, pp. 180-191.
“The Use Of Walsh Functions For Multiplexing Signals”, Davidson, I.A., Applications Of Walsh Functions, 1970 Proceedings, pp. 23-25.

Affiliated with

Also associated with

Rating

PN code selection for synchronous CDMA does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with PN code selection for synchronous CDMA, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and PN code selection for synchronous CDMA will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3236235