REDUCING FALSE DETECTION IN AN HSDPA 3G TERMINAL

• US 20080298334A1
• Filed: 05/31/2007
• Published: 12/04/2008
• Est. Priority Date: 05/31/2007
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Inventors: Arviv, Eliahou, Carmon, Rafael, Issakov, Simon
• Granted Patent: US 7,912,028 B2
• Time in Patent Office: Days
• US Class Current: 370/341
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04J 13/0044 OVSF [orthogonal variable spreading factor]
• CPC Class Codes: H04L 1/0048 in conjunction with detection of multiuser or interfering signals, e.g. iteration between CDMA or MIMO detector and FEC decoder for spatial equalizer H04L25/03286

Abstract

In one embodiment, a method for determining whether an encoded message in a shared channel is not intended for a communications device. The method includes: (a) decoding the message to recover a multi-bit codeword; (b) determining whether the codeword is valid or invalid, wherein, if the codeword is determined to be invalid, then the encoded message is not intended for the communications device; and (c) if the codeword is determined to be valid, then performing one or more other steps of the method to determine whether the encoded message in the shared channel is not intended for the communications device.

Claims

1. A method for determining whether an encoded message in a shared channel is not intended for a communications device, the method comprising:

(a) decoding the message to recover a multi-bit codeword;

(b) determining whether the codeword is valid or invalid, wherein, if the codeword is determined to be invalid, then the encoded message is not intended for the communications device; and

(c) if the codeword is determined to be valid, then performing one or more other steps of the method to determine whether the encoded message in the shared channel is not intended for the communications device.

2. The invention of claim 1, wherein step (b) comprises determining whether the bit value of the codeword matches one of a set of specified codeword bit values.

3. The invention of claim 1, wherein the shared channel is a High-Speed Shared Control Channel (HS-SCCH).

4. The invention of claim 1, wherein:

the message comprises a first part and a second part;

the codeword is encoded in the first part;

if the method does not determine that the message is not intended for the communications device, then the second part of the message is decoded.

5. The invention of claim 4, wherein the second part of the message encodes data for demodulating another shared channel.

6. The invention of claim 1, wherein steps (a) and (b) are performed in parallel for a plurality of shared channels.

7. The invention of claim 6, wherein the one or more other steps comprise:

at least one single-channel step performed in parallel for each of the plurality of shared channels; and

at least one multi-channel step performed for the plurality of shared channels.

8. The invention of claim 7, wherein the at least one single-channel step comprises:

(1) generating a correlation value for the codeword; and

(2) comparing the correlation value to a threshold to determine whether the message is not intended for the communications device; and

the at least one multi-channel step comprises;

(1) selecting a shared channel having a minimum correlation value from the plurality of shared channels;

(2) re-encoding and rate-matching the codeword for the selected shared channel to generate an encoded, rate-matched codeword;

(3) calculating a re-encoded correlation value between the message and the encoded, rate-matched codeword; and

(4) thresholding the calculated re-encoded correlation value to determine whether the message is not intended for the communications device.

9. The invention of claim 8, wherein:

the re-encoded correlation value is determined using the equation

10. The invention of claim 8, wherein:

the correlation value C_x is calculated by the equation

11. A communications device adapted to determine whether an encoded message in a shared channel is not intended for the communications device, the communications device comprising:

a decoder adapted to decode the message to recover a multi-bit codeword;

a post-decoding block adapted to;

(i) determine whether the codeword is valid or invalid, wherein, if the codeword is determined to be invalid, then the encoded message is not intended for the communications device, and

(ii) determine whether the encoded message in the shared channel is not intended for the communications device, if the codeword is determined to be valid.

12. The invention of claim 11, wherein the post-decoding block is adapted to determine whether the codeword is valid or invalid by determining whether the bit value of the codeword matches one of a set of specified codeword bit values.

13. The invention of claim 11, wherein the shared channel is a High-Speed Shared Control Channel (HS-SCCH).

14. The invention of claim 11, wherein:

the message comprises a first part and a second part;

the codeword is encoded in the first part;

if the post-decoding block determines that the message is not intended for the communications device, then the second part of the message is decoded.

15. The invention of claim 14, wherein the second part of the message encodes data for demodulating another shared channel.

16. The invention of claim 11, wherein the post-decoding block is adapted to determine in parallel, for a plurality of shared channels, whether the codeword is valid or invalid.

17. The invention of claim 16, wherein the post-decoding block is adapted, if the codeword is determined to be valid, to:

(i) perform at least one single-channel function in parallel for each of the plurality of shared channels, and

(ii) perform at least one multi-channel function for the plurality of shared channels.

18. The invention of claim 17, wherein the at least one single-channel function comprises:

(1) generating a correlation value for the codeword; and

(2) comparing the correlation value to a threshold to determine whether the message is not intended for the communications device; and

the at least one multi-channel function comprises;

(1) selecting a shared channel having a minimum correlation value from the plurality of shared channels;

(2) re-encoding and rate-matching the codeword for the selected shared channel to generate an encoded, rate-matched codeword;

(3) calculating a re-encoded correlation value between the message and the encoded, rate-matched codeword; and

(4) thresholding the calculated re-encoded correlation value to determine whether the message is not intended for the communications device.

19. The invention of claim 18, wherein:

the re-encoded correlation value is determined using the equation

20. The invention of claim 18, wherein:

the correlation value C_x is calculated by the equation