Sequential combined QPCH demodulation

• US 6,771,616 B2
• Filed: 09/13/2001
• Issued: 08/03/2004
• Est. Priority Date: 01/17/2000
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Roh, Mark, Abrishamkar, Farrokh
• Primary Examiner(s): ZIMMERMAN, BRIAN A
• Application Number:
  US09/952,722
• Publication Number:
  US 20020142784A1
• Time in Patent Office: 1,055 Days
• Field of Search: 340/7.42, 370/311, 370/320, 370/329, 370/335, 455/458, 455/432, 455/522, 455/574
• US Class Current: 370/320
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• CPC Class Codes: H04W 52/0245 according to signal strength
• CPC Class Codes: H04W 68/00 User notification, e.g. alerting and paging, for incoming communication, change of service or the like
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A system determines if a primary paging channel should be received based on an examination of a quick paging channel. A first QPCH symbol is examined (102) and the normalized pilot energy is determined (104). If the normalized pilot energy is above a first threshold (106), the symbol is demodulated and the QPCH-symbol-to-pilot-energy ratio is determined (110) and compared against another threshold (114). If the normalized pilot energy is below the first threshold, the system proceeds to the second QPCH symbol immediately. Based on the two comparisons, a second QPCH signal is examined (108) or the system sleeps (116). If the second signal is examined, and if its normalized pilot energy is high enough, it also is demodulated and the ratio of the sum-of-the-combined-QPCH-symbols to the sum-of-the-combined-pilot-energies is determined (122). If this ratio exceeds a threshold (124), the primary paging channel is processed (120); otherwise the system sleeps (116).

Claims

1. An efficient system for determining if a primary paging channel should be received and processed via a wireless communications device based on a quick paging channel in a wireless communications system comprising:

first means for receiving an electromagnetic signal having pilot signal and quick paging signal components;

second means for ascertaining if a second symbol of said quick paging channel signal should be immediately analyzed based on a first quality parameter and a first decision metric associated with a first symbol of said quick paging signal and providing a first indication in response thereto, said first decision metric representative of a value of said first symbol; and

third means for determining, via said second symbol, if said primary paging channel should be immediately processed based on a second quality parameter and a second decision metric associated with said second symbol and providing a second indication in response thereto when said first indication indicates that said second symbol should be immediately analyzed.

2. The system of claim 1 wherein said first quality parameter and said second quality parameter are based on a portion of said pilot signal associated with said first symbol and said second symbol, respectively, said first and second quality parameters indicative of a quality of a signal environment in which said electromagnetic signal is propagating.

3. The system of claim 2 wherein said first decision metric is determined in accordance with the following metric (D₁):

$D_1=\frac{{\mathrm{QP}}_1}{E_{\mathrm{pilot}<br><br>\text{\hspace{1em}<br><br>}<br><br>1}},$

where D₁ is said first decision metric;

QP₁ is a dot product, cross product, or a combination thereof of said first symbol with an estimate of said pilot signal associated with said first symbol; and

E_pilot1 is an energy of said pilot signal associated with said first symbol.

4. The system of claim 3 wherein

said second decision metric is a demodulation symbol (D) determined in accordance with the following equation:

$D=\frac{{\mathrm{QP}}_1+{\mathrm{QP}}_2}{E_{\mathrm{pilot}<br><br>\text{\hspace{1em}<br><br>}<br><br>1}+E_{\mathrm{pilot}<br><br>\text{\hspace{1em}<br><br>}<br><br>2}},$

where QP₂ is a dot product, cross product, or a combination thereof of said second symbol with an estimate of said pilot signal associated with said second symbol; and

E_pilot2 is an energy of said second portion of said pilot signal.

5. An efficient system for determining if a primary paging channel should be received and processed via a wireless communications device based on a quick paging channel in a wireless communications system comprising:

first means for receiving an electromagnetic signal having pilot signal and quick paging signal components;

second means for ascertaining whether a first symbol or a signal environment of a second symbol of said quick paging channel signal should be immediately analyzed based on a first quality parameter and providing a first indication in response thereto, said first quality parameter based on said pilot signal and indicative of a quality of a signal environment in which said electromagnetic signal is propagating;

third means for selectively processing said first symbol to determine a first symbol metric and determining, based on said first symbol metric, if said signal environment of said second symbol should be immediately analyzed and providing a second indication in response thereto when said first indication indicates that said first symbol should be immediately processed;

fourth means for providing a second quality parameter indicative of a quality of a signal environment in which said electromagnetic signal is propagating based on said pilot signal and determining whether a second metric incorporating said second symbol should be computed or said primary paging channel should be processed based on said second quality parameter associated with said second symbol and providing a fourth indication in response thereto when said third indication indicates that said signal environment of said second symbol should be immediately analyzed; and

fourth means for determining if said primary paging channel should be processed based on said second metric when said fourth indication indicates that said primary paging channel should not be immediately processed.

6. The system of claim 5 wherein said second metric includes one or more combined decision metrics associated with both said first symbol and said second symbol when said first indication indicates that said second symbol should be processed and providing a second indication response thereto.

7. A system for determining, via a quick paging signal associated with a quick paging channel, whether a forthcoming page on a primary paging channel should be received and processed comprising:

first means for receiving an electromagnetic signal and providing one or more decision parameters based on a quality of a signal environment through which said received signal propagates and/or based on a value of a first symbol and/or a second symbol of a quick paging channel signal component of said received signal in response to the receipt of said electromagnetic signal and

second means for selectively comparing said one or more decision parameters associated with a first quick paging channel symbol and/or a second paging channel symbol to one or more corresponding predetermined thresholds in response to said control signal and providing a first indication in response thereto, said first indication indicative of whether said forthcoming paging channel should be received and processed.

8. An efficient method for determining if a primary paging channel should be received and processed via a wireless communications device based on a quick paging channel in a wireless communications system comprising the steps of:

receiving an electromagnetic signal having pilot signal and quick paging signal components;

ascertaining if a second symbol of said quick paging channel signal should be immediately analyzed based on a first quality parameter and a first decision metric associated with a first symbol of said quick paging signal and providing a first indication in response thereto, said first decision metric representative of a value of said first symbol; and

determining, via said second symbol, if said primary paging channel should be immediately processed based on a second quality parameter and a second decision metric associated with said second symbol and providing a second indication in response thereto when said first indication indicates that said second symbol should be immediately analyzed.

9. A system for interpreting a quick paging channel signal in a wireless communications system comprising:

first means for analyzing a received signal and a signal environment associated with said quick paging channel to determine if one or more symbols of said received signal are valid and providing a first indication in response thereto;

second means for providing a value indicative of a message included in said quick paging channel based on said first indication and said one or more symbols, wherein said one or more symbols include a first symbol and a second symbol, and said first means includes means for analyzing said signal environment and providing a parameter indicative of said signal environment via a pilot signal included in said received signal; and

third means for indicating that said first symbol and said second symbol are unreliable based on said parameter and selectively disabling said second means in response thereto.

10. The system of claim 9 wherein said second means includes means for selectively calculating one or more of the following metrics (D₁ or D):

$D_1=\frac{{\mathrm{QP}}_1}{E_{\mathrm{pilot}<br><br>\text{\hspace{1em}<br><br>}<br><br>1}},D=\frac{{\mathrm{QP}}_1+{\mathrm{QP}}_2}{E_{\mathrm{pilot}<br><br>\text{\hspace{1em}<br><br>}<br><br>1}+E_{\mathrm{pilot}<br><br>\text{\hspace{1em}<br><br>}<br><br>2}},$

where D₁ is said first decision metric;

QP₁ is a dot product, cross product, or a combination thereof of said first symbol with an estimate of said pilot signal associated with said first symbol;

QP₂ is a dot product, cross product, or a combination thereof of said second symbol with an estimate of said pilot signal associated with said second symbol;

E_pilot1 is an energy of said pilot signal associated with said first symbol; and

E_pilot2 is an energy of said second portion of said pilot signal.

11. The system of claim 10 wherein said second means includes means for comparing one or more of said metrics to one or more predetermined thresholds and providing said value in response thereto.

12. A system for interpreting a quick paging channel signal in a wireless communications system comprising:

a receiver circuit having an antenna and a receive chain;

a pilot estimation circuit in communication with said receiver;

a total received energy computation circuit in communication with said receiver;

a quick paging channel symbol combiner in communication with said pilot estimation circuit, said total received energy computation circuit, and said receiver; and

a page detector in communication with said quick paging channel symbol combiner.

13. The system of claim 12 wherein said receiver further includes a sample random access memory (RAM) connected at an output of said receive chain, an interpolator connected at an output of said sample random access memory, a despreading circuit.

14. The system of claim 13 wherein said despreading circuit includes a demodulator.

15. The system of claim 13 wherein said sample RAM and said interpolator are included in a digital baseband processor.

16. The system of claim 15 wherein said pilot estimation circuit includes a pilot estimator in communication with a pilot energy computation circuit.

17. An efficient method for determining if a primary paging channel should be received and processed via a wireless communications device based on a quick paging channel in a wireless communications system comprising the steps of:

receiving an electromagnetic signal having pilot signal and quick paging signal components;

ascertaining if a second symbol of said quick paging channel signal should be immediately analyzed based on a first quality parameter and a first decision metric associated with a first symbol of said quick paging signal and providing a first indication in response thereto, said first decision metric representative of a value of said first symbol; and

determining, via said second symbol, if said primary paging channel should be immediately processed based on a second quality parameter and a second decision metric that incorporates said second symbol and providing a second indication in response thereto when said first indication indicates that said second symbol should be immediately analyzed, said first and second quality parameters indicative of a quality of a signal environment in which said electromagnetic signal is propagating.