Method and apparatus for joint transmission of multiple data signals in spread spectrum communication systems

• US 5,757,767 A
• Filed: 10/29/1996
• Issued: 05/26/1998
• Est. Priority Date: 04/18/1995
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zehavi, Ephraim
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Phillips, Matthew C.
• Application Number:
  US08/741,229
• Time in Patent Office: 574 Days
• Field of Search: 370/209, 370/208, 370/203, 370/206, 370/207, 370/320, 370/335, 370/342, 370/441, 375/25
• US Class Current: 370/208
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]
• CPC Class Codes: H04J 13/0048 Walsh
• CPC Class Codes: H04J 13/10 Code generation

Abstract

A more efficient and less complex structure and method for combining multiple user channels onto a single carrier frequency in spread spectrum communication systems. A single transformation element, such as a fast Hadamard Transformation processor, is used to orthogonally encode and combine a series of subscriber digital data signals in parallel. Portions of the orthogonally encoded and combined data signals are then selected over preselected time intervals to generate a single encoded data signal which is subsequently PN spread, subjected to analog signal processing, and transmitted to system subscribers. This is typically effected by summing digital values in an array of data signal combiners. An exemplary data transformation device uses at least one of a preselected set of orthogonal functions as a controlling pattern for interconnection of the combining elements. Each of the combining elements receives at least two input signals, either data or previously combined data, and produces a combined encoded signal output. The order of combination maps the input data signals into an orthogonal combined signal. Portions of the combined data signals are then selected and transferred in order as a serialized data stream for subsequent spreading and transmission as a communication signal.

Claims

1. Apparatus for orthogonally encoding a plurality of digital data signals in a spread spectrum communication system in which information is communicated over orthogonally encoded data signals which are subsequently spectrum spread, comprising:

first multiplexing means for receiving a plurality of said digital data signals in parallel and forming them into single a bit-wise serial data stream;

second multiplexing means for receiving a plurality of channel gain factors in parallel, each corresponding to a predetermined digital data signal, and forming them into a single bit-wise serial gain stream; and

a bit serial Fast Hadamard transformation means connected to receive said bit-wise serial data and gain streams for combining together in a corresponding pairwise fashion and for applying at least one preselected orthogonal function thereto from a plurality of orthogonal functions so as to produce an orthogonally covered gain adjusted data signal.

2. The apparatus of claim 1 wherein said plurality of orthogonal functions comprise Walsh functions.

3. The apparatus of claim 1 wherein said plurality of orthogonal functions comprise short orthogonal PN code sequences, with a period less than 2¹⁵ chips in length.

4. The apparatus of claim 1 further comprising control means coupled to said Fast Hadamard transformation means for generating a transformation structure for use by said Fast Hadamard transformation means.

5. The apparatus of claim 4 wherein said control means dynamically adjusts said transformation structure in response to data signals being received.

6. The apparatus of claim 1 wherein said plurality of orthogonal functions comprise short orthogonal PN code sequences with a period on the order of 27 chips in length.

7. The apparatus of claim 1 further comprising:

means for spreading said orthogonally covered gain adjusted data signal using at least one predetermined PN spreading code; and

a bit-wise filter bank for removing unwanted frequency components from said orthogonally covered gain adjusted data signal.

8. The apparatus of claim 7 wherein said bit-wise filter bank comprises a plurality of one bit input FIR filters.

9. The apparatus of claim 1 further comprising at least one gain adjusting element connected to receive the output from said Fast Hadamard transformation means to perform an additional spreading function for symbol data output therefrom.

10. The apparatus of claim 9 further comprising:

delay means connected to receive an output from said gain adjusting element for delaying a gain adjusted signal by a preselected period on the order of the length of one orthogonal function period; and

summation means for adding an output of said gain adjusting element to a delayed version thereof.

11. A method of orthogonally encoding a plurality of digital data signals to be transmitted to system subscribers over separate user channels in a spread spectrum communication system in which information is communicated over orthogonally encoded data signals which are subsequently spectrum spread, comprising the steps of:

receiving a plurality of said digital data signals in parallel for active channels, and multiplexing them into single a bit-wise serial data stream;

receiving a plurality of channel gain factors in parallel, each corresponding to a predetermined digital data signal, and multiplexing them into a single bit-wise serial gain stream; and

receiving and combining together said bit-wise serial data and gain streams in a bit serial Fast Hadamard transformation means, in a corresponding pairwise fashion, and applying at least one preselected orthogonal function thereto from a plurality of orthogonal functions so as to produce an orthogonally covered gain adjusted data signal.

12. The method of claim 11 wherein said plurality of orthogonal functions comprise Walsh functions.

13. The method of claim 11 wherein said plurality of orthogonal functions comprise short orthogonal PN code sequences, with a period less than 2¹⁵ chips in length.

14. The method of claim 11 wherein said plurality of orthogonal functions comprise short orthogonal PN code sequences, with a period on the order of 2⁷ chips in length.

15. The method of claim 11 further comprising the steps of:

spreading said orthogonally covered gain adjusted data signal using at least one predetermined PN spreading code; and

removing unwanted frequency components from said orthogonally covered gain adjusted data signal using a bit-wise filter bank.

16. The method of claim 11 further comprising the step of applying an additional gain adjustment function to symbol data output from said Fast Hadamard transformation means.

17. The method of claim 16 further comprising the steps of:

receiving gain adjusted symbol data and applying a preselected period of delay thereto, on the order of the length of one orthogonal function period; and

adding gain adjusted symbol data to a delayed version thereof.

18. The method of claim 11 further comprising the steps of generating a transformation structure for use by said Fast Hadamard transformation means;

and transferring said transformation structure thereto.

19. The method of claim 18 further comprising the step of dynamically adjusting said transformation structure in response to data signals being received.