Method for compensating for multi-path of a CDMA reverse link utilizing an orthogonal channel structure

• US 8,537,656 B2
• Filed: 01/29/2004
• Issued: 09/17/2013
• Est. Priority Date: 07/19/2000
• Status: Active Grant

• Current Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Original Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Inventors: Proctor, James A. Jr.
• Primary Examiner(s): Harper, Kevin C
• Assistant Examiner(s): MURPHY, RHONDA L
• Application Number:
  US10/767,843
• Publication Number:
  US 20040257975A1
• Time in Patent Office: 3,519 Days
• Field of Search: None
• US Class Current: 370/203
• CPC Class Codes: H04B 7/2628 using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] H04B7/2618 takes precedence
• CPC Class Codes: H04J 13/004 Orthogonal
• CPC Class Codes: H04J 13/0048 Walsh
• CPC Class Codes: H04J 13/18 Allocation of orthogonal codes
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition

Abstract

A base station receives a reverse link signal from a given field unit that includes a common code (i.e., shared by other field units) and a unique orthogonal code (i.e., distinguishing the given field unit from other field units). The reverse link signal travels in a multi-path environment along a primary path and at least one secondary path. The base station makes a diversity decision based on the unique orthogonal code seen at two different phases. The base station determines a gross timing offset to align the common code of the given field unit with the common code from other field units using unique orthogonal codes. The given field unit makes a corresponding coarse adjustment of the phase of its common code.

Claims

1. An apparatus for receiving reverse link signals from a plurality of subscriber units comprising:

a receiver that receives a first plurality of reverse link signals and a second plurality of reverse link signals in a time interval, wherein each said reverse link signal of the first plurality of reverse link signals is derived from at least a common pseudo noise (PN) sequence and unique orthogonal sequence and each said reverse link signal of the second plurality of reverse link signals is derived from a unique pseudo noise (PN) sequence, wherein each said reverse link signal of the first plurality of reverse link signals is sent by a subscriber unit when not actively transmitting user data; and

a timing controller that determines a timing offset associated with at least one reverse link signal to align a timing of the at least one reverse link signal with reverse link signals from other subscriber units, wherein the one reverse link signal is at least one of the first plurality of reverse link signals or the second plurality of reverse link signals.

2. The apparatus according to claim 1 wherein the timing controller determines a fine timing offset and causes a fine phase adjustment of the common pseudo noise (PN) sequence of the reverse link signal.

3. The apparatus according to claim 1 wherein the timing controller provides the gross timing offsets to a subscriber unit in the form of a timing command.

4. The apparatus according to claim 1 wherein the timing controller provides the gross timing offsets to a subscriber unit in the form of a timing report.

5. The apparatus according to claim 1 further including a power controller that determines a power level of the aligned reverse link signal and provides feedback of the power level to a subscriber unit.

6. The apparatus according to claim 5 wherein the power controller provides the power level to the subscriber unit in the form of a power command.

7. The apparatus according to claim 5 wherein the power controller provides the power level to the subscriber unit in the form of a power report.

8. A method of receiving reverse link signals from a plurality of subscriber units comprising:

receiving a first and a second plurality of reverse link signals in a time interval, wherein each reverse link signal of the first plurality of reverse link signals is derived from a common pseudo noise sequence and a unique orthogonal sequence and each reverse link signal of the second plurality of reverse link signals is derived from a unique pseudo noise sequence, wherein each said reverse link signal of the first plurality of reverse link signals is sent by a subscriber unit when not actively transmitting user data; and

determining a timing offset associated with at least one reverse link signal to align the at least one reverse link signal with reverse link signals from other subscriber units, wherein the one reverse link signal is at least one of the first plurality of reverse link signals or the second plurality of reverse link signals.

9. The method according to claim 8 further including providing gross timing offsets to a subscriber unit in a form of a timing command.

10. The method according to claim 8 further including providing the gross timing offsets to a subscriber unit in a form of a timing report.

11. The method according to claim 8 further including determining a power level of the aligned reverse link signal and providing feedback of the power level to a subscriber unit.

12. The method according to claim 11 wherein providing the power level to send to the subscriber unit includes transmitting the power level feedback to the subscriber unit in the form of a power command.

13. The method according to claim 11 wherein providing the power level to send to the subscriber unit includes transmitting the power level feedback to the subscriber unit in the form of a power report.

14. A subscriber unit comprising:

at least one processor configured to receive a timing offset,

wherein the at least one processor is further configured to transmit a reverse link signal derived from a common pseudo noise sequence and a unique orthogonal sequence;

wherein a timing of the reverse link signal is adjusted in response to the received timing offset; and

wherein the common pseudo noise sequence and different unique orthogonal sequences are used by a first plurality of other subscriber units in a same time interval for reverse link transmissions and unique different pseudo noise sequences are used by a second plurality of other subscriber units in the same time interval for reverse link transmissions, wherein each said reverse link signal is sent by a first plurality of subscriber units when not actively transmitting user data.

15. The subscriber unit of claim 14, wherein the at least one processor is configured to transmit a reverse link signal derived from the common pseudo noise sequence and the unique orthogonal sequence and is also configured to transmit a reverse link signal derived from a unique pseudo noise sequence.