Reduced peak-to-average transmit power high data rate CDMA wireless communication system

• US 5,926,500 A
• Filed: 06/07/1996
• Issued: 07/20/1999
• Est. Priority Date: 05/28/1996
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Odenwalder, Joseph P.
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Roundtree, Joseph
• Application Number:
  US08/660,438
• Time in Patent Office: 1,138 Days
• Field of Search: 370/206, 370/208, 370/209, 370/320, 370/339, 370/342, 370/441, 370/487, 370/491, 370/535, 370/538, 375/200, 375/206, 375/208, 375/267, 375/265, 380/34, 455/33.1, 455/54.1
• US Class Current: 375/144
• CPC Class Codes: H04B 7/264 for data rate control
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27

Abstract

A novel and improved method and apparatus for high rate CDMA wireless communication is described. In accordance with one embodiment of the invention, a set of individually gain adjusted subscriber channels are formed via the use of a set of orthogonal subchannel codes having a small number of PN spreading chips per orthogonal waveform period. Data to be transmitted via one of the transmit channels is low code rate error correction encoded and sequence repeated before being modulated with one of the subchannel codes, gain adjusted, and summed with data modulated using the other subchannel codes. The resulting summed data is modulated using a user long code and a pseudorandom spreading code (PN code) and upconverted for transmission. The use of the short orthogonal codes provides interference suppression while still allowing extensive error correction coding and repetition for time diversity to overcome the Raleigh fading commonly experienced in terrestrial wireless systems. In the exemplary embodiment of the invention provided, the set of sub-channel codes are comprised of four Walsh codes, each orthogonal to the remaining set and four chips in duration. The use of four sub-channels is preferred as it allows shorter orthogonal codes to be used, however, the use of a greater number of channels and therefore longer codes is consistent with the invention. In a preferred exemplary embodiment of the invention, pilot data is transmitted via a first one of the transmit channels and power control data transmitted via a second transmit channel. The remaining two transmit channels are used for transmitting non-specified digital data including user data or signaling data, or both. In an exemplary embodiment, one of the two non-specified transmit channels is configured for BPSK modulation and transmission over the quadrature channel.

Claims

1. A method for generating modulated data for transmission from a first subscriber unit in a set of subscriber units to a base station in communication with the set of subscriber units comprising the steps of:

a) modulating first data with a first orthogonal code to generate first channel data;

b) modulating second data with a second orthogonal modulation code to produce second channel data;

c) modulating said first channel data with an in-phase spreading code and a quadrature-phase spreading code to generate first in-phase spread data and first quadrature-phase spread data;

d) modulating said second channel data with said in-phase spreading code and said quadrature-phase spreading code to generate second in-phase spread data and second quadrature-phase spread data;

e) subtracting said second quadrature-phase spread data from said first in-phase spread data yielding an in-phase term; and

f) adding said second in-phase spread data with said first quadrature-phase spread data yielding a quadrature-phase term.

2. The method as set forth in claim 1 further comprising the steps of:

gain adjusting said first channel data; and

gain adjusting said second channel data.

3. The method as set forth in claim 1 wherein:

said first data is pilot data; and

said second data is user data.

4. The method as set forth in claim 1 further comprising the steps of:

modulating third channel data with a third Walsh code;

adding said third channel data into said first channel data, wherein

said first channel data is pilot data, and

said second channel data is power control data.