Reception-synchronization protecting device and reception-synchronization protection method

• US 6,229,848 B1
• Filed: 11/23/1999
• Issued: 05/08/2001
• Est. Priority Date: 11/24/1998
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Tanaka, Hiroshi
• Primary Examiner(s): Bocure, Tesfaldet
• Application Number:
  US09/447,579
• Time in Patent Office: 532 Days
• Field of Search: 375/354, 375/355, 375/227, 375/365, 370/503, 370/512, 370/513
• US Class Current: 375/227
• CPC Class Codes: H04J 3/0688 Change of the master or reference, e.g. take-over or failure of the master
• CPC Class Codes: H04L 7/0083 taking measures against momentary loss of synchronisation, e.g. inhibiting the synchronisation, using idle words or using redundant clocks

Abstract

A reception-synchronization protecting device comprises strength measuring means, an S/N ratio estimating circuit, a protection window size determining circuit, a timing estimating circuit, and a protection window adding circuit. The strength measuring means is used for measuring a signal strength of a CCS signal contained in a received frame and producing a measured result. The S/N ratio estimating circuit is used for estimating an S/N (a Signal-to-Noise) ratio of the received frame with basing on the measured result previously measured by the signal strength measuring circuit. The protection window size determining circuit is used for determining a size of a protection window with basing on the estimated S/N ratio estimated by the S/N ratio estimating circuit. The timing estimating circuit is used for estimating an expected position of the received frame with basing on the measured result previously measured by the signal strength measuring circuit. The protection window adding circuit is used for adding protection window having the determined size determined by the protection window size determining circuit at each of front and rear ends of an expected timing frame to be contained in the received frame, with basing on the estimated position and the estimated S/N ratio of the received frame respectively estimated by the S/N ratio estimating circuit and the timing estimating circuit.

Claims

1. A reception-synchronization protecting device comprising:

strength measuring means for measuring a signal strength of a CCS (Common Line Signal) signal contained in a received frame and producing a measured result;

S/N ratio estimating means for estimating an S/N (a Signal-to-Noise) ratio of the received frame based on said measured result previously measured by said strength measuring means;

protection window size determining means for determining a size of a protection window based on the estimated S/N ratio estimated by said S/N ratio estimating means;

timing estimating means for estimating an expected position of the received frame based on said measured result previously measured by said strength measuring means; and

protection window adding means for adding protection window having the determined size determined by said protection window size determining means at each of front and rear ends of an expected timing frame to be contained in the received frame, based on the estimated expected position and the estimated S/N ratio of the received frame respectively estimated by said S/N ratio estimating means and said timing estimating means.

2. A reception-synchronization protecting device as claimed in claim 1, wherein said protection window size determining means determines the size of the protection window as to be the most suitable for the estimated S/N ratio estimated by said S/N ratio estimating means, based on a relationship between a timing distribution of the CCS signal and a signal strength degradation caused by a timing error of the received frame.

3. A reception-synchronization protecting device as claimed in claim 1, wherein the timing estimating means determines the expected position for adding the protection window as to be the most suitable for the estimated S/N ratio estimated by said S/N ratio estimating means, based on a relationship between a timing distribution of the CCS signal and a signal strength degradation caused by a timing error of the received frame.

4. A reception-synchronization protecting device as claimed in claim 1, wherein said protection window size determining means determines a profile of at least one of the protection windows at the front and the rear ends of the received frame, and which thereby minimizes a power loss caused by a timing error of an actual timing frame.

5. A reception-synchronization protecting device as claimed in claim 1, wherein said protection window size determining means determines profiles of the protection windows at the front and the rear ends of the received frame so that the profiles are asymmetrical to each other, and which thereby minimizes a power loss caused by a timing error of an actual timing frame.

6. A reception-synchronization protecting method comprising:

a signal strength measuring step for measuring a signal strength of a CCS (Common Line Signal) signal contained in a received frame and producing a measured result;

an S/N ratio estimating step for estimating an S/N (a signal-to-noise) ratio of the received frame based on said measured result previously measured in said strength measuring step;

a protection window size determining step for determining a size of a protection window based on the estimated S/N ratio estimated in said S/N ratio estimating step;

a timing estimating step for estimating an expected position of the received frame based on said measured result previously measured in said strength measuring step; and

a protection window adding step for adding protection window having the determined size determined in said protection window size determining step at each of front and rear ends of an expected timing frame to be contained in the received frame, based on the estimated expected position of the received frame and the estimated S/N ratio of the received frame respectively estimated in said S/N ratio estimating step and said timing estimating step.

7. A reception-synchronization protecting method as claimed in claim 6, wherein said protection window size determining step comprises a step of determining the size of the protection window as to be the most suitable for thee estimated S/N ratio estimated in said S/N ratio estimating step, based on a relationship between a timing distribution of the CCS signal and a signal strength degradation caused by a timing error of the received frame.

8. A reception-synchronization protecting method as claimed in claim 6, wherein said timing estimating step comprises a step of determining the expected position for adding the protection window as to be the most suitable for the estimated S/N ratio estimated in said S/N ratio estimating step, based on a relationship between a timing distribution of the CCS signal and a signal strength degradation caused by a timing error of the received frame.

9. A reception-synchronization protecting method as claimed in claim 6, wherein said protection window size determining step comprise a step of determining a profile of at least one of the protection windows at the front and the rear ends of the received frame and a step of thereby minimizing a power loss caused by a timing error of an actual timing frame.

10. A reception-synchronization protecting method as claimed in claim 6, wherein said protection window size determining step comprises a step of determining profiles of the protection windows at the front and the rear ends of the received frame so that the profiles are asymmetrical to each other and a step of thereby minimizing a power loss caused by a timing error of an actual timing frame.