# US 8,542,783 B2 · Method for unifying secondary synchronization signal detection and frame timing synchronization

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- Number: US 8,542,783 B2
- Document ID: US8542783B2
- Status: Granted
- Kind: B2
- Application number: 13/259,491
- Filed: 2010-04-02
- Published: 2012-04-19
- Granted: 2013-09-24
- Earliest claimed: 2009-06-30
- Assignees: Zte Corporation
- Applicants: Peng Zhou; Yuefeng Chen; Yijun Shi
- Inventors: Peng Zhou; Yuefeng Chen; Yijun Shi
- Web page: https://patentgrep.com/patent/US8542783B2

## CPC

- H04W 56/00: Synchronisation arrangements
- H04B 1/70752: {Partial correlation}
- H04J 11/0076: {Acquisition of secondary synchronisation channel, e.g. detection of cell-ID group}
- H04L 27/2613: {Structure of the reference signals}
- H04L 27/2656: {Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation}
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04B: TRANSMISSION
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

The present invention discloses a method for joint secondary synchronization signal detection and frame timing synchronization, including: (1) generating local secondary synchronization sequences SSC1—n and SSC2—n according to a sector number of a cell group; (2) converting a received time domain signal to a frequency domain signal to obtain secondary synchronization signals S1 and S2 to be detected; (3) performing inner product operation to obtain P1—n=P1—n−1+[S1,SSC1—n]+[S2,SSC2—n], and P2—n=P2—n−1+[S1,SSC2—n]+[S2,SSC1—n]; (4) selecting the maximum value P of absolute values of correlation values in the P1—n and P2—n, and judging whether the maximum value P is greater than a preset threshold Tmax, (5) if yes, taking the index of the maximum value P as an ID number of the cell group, or else, further carrying out step (2), and then further carrying out step (3).

## Claims

### Claim 1

A method for joint secondary synchronization signal detection and frame timing synchronization, comprising following steps:
(1) generating two local secondary synchronization sequences, i.e. SSC1—n and SSC2—n, according to a sector number of a cell group, wherein n is an index of multiple-frame average, and at this time n=0;
(2) converting received one frame time domain signal to frequency domain to obtain secondary synchronization signals S1 and S2 to be detected respectively corresponding to two half-frames of the one frame time domain signal;
(3) carrying out inner products on said S1 and S2 with SSC1—n and SSC2—n respectively to obtain [S1,SSC1—n], [S2,SSC2—n], [S1,SSC2—n], [S2,SSC1—n], then combining inner product results to obtain sets [S1,SSC1—n]+[S2,SSC2—n] and [S1,SSC2—n]+[S2,SSC1—n], and letting P1—n=P1—n−1+[S1,SSC1—n]+[S2,SSC2—n], P2—n=P2—n−1+[S1,SSC2—n]+[S2,SSC1—n], wherein P1—−1 and P2—−1 are empty sets;
(4) selecting a maximum value P of absolute values of correlation values in the P1—n and P2—n, and judging whether the maximum value P is greater than a preset threshold Tmax,
(5) if yes, taking the index of the maximum value P as an ID number of the cell group, and completing one frame timing synchronization by judging whether the maximum value occurs in P1—n or P2—n; if not, comparing the absolute values of the correlation values in the P1—n and P2—n with a threshold Tccv, selecting the secondary synchronization sequences corresponding to the correlation value of which the absolute value is not less than the Tccv in the P1—n and P2—n as new secondary synchronization sequences SSC1—n and SSC2—n, increasing the index by 1, and then jumping to a step of the multiple-frame average, namely carrying out step (2), and then carrying out step (3).

### Claim 2 (depends on 1)

The method as claimed in claim 1, wherein in said step (3), further comprises:
comparing the absolute values of the correlation values with a same cell group number in the P1—n and P2—n with the preset threshold Tccv, and if the absolute value of the correlation value corresponding to the same cell group number in the P1—n and P2—n is less than the Tccv, then discarding this cell group number.

### Claim 3 (depends on 2)

The method as claimed in claim 2, wherein a value of said Tccv is normalized to 30.

### Claim 4 (depends on 1)

The method as claimed in claim 1, wherein before said step (1), said method further comprises:
carrying out cross correlation on the received time domain signals and a local primary synchronization sequence, and obtaining the sector number of the cell group by detecting a correlation peak.

### Claim 5 (depends on 1)

The method as claimed in claim 1, wherein said step (2) comprises:
for the received time domain signals of one frame, taking use of a half frame timing synchronization result and blind detection to obtain a cyclic prefix mode, and at this time, demodulating said time domain signals by orthogonal frequency division multiplex (OFDM) to frequency domain to obtain said secondary synchronization signals S1 and S2 to be detected.

### Claim 6 (depends on 5)

The method as claimed in claim 5, wherein before said step (1), said method further comprises:
carrying out cross correlation on the received time domain signals and a local primary synchronization sequence, and obtaining said half frame timing synchronization result by detecting the correlation peak.

### Claim 7

An apparatus for joint secondary synchronization signal detection and frame timing synchronization, comprising:
a local secondary synchronization sequence generation module, which is configured to: generate two local secondary synchronization sequences, i.e. SSC1—n and SSC2—n, according to a sector number of a cell group, and send the local secondary synchronization sequences SSC1—n and SSC2—n to a multiple-frame average module, wherein n is an index of multiple-frame average, and n=0;
the multiple-frame average module, which is configured to: convert received one frame time domain signal to frequency domain to obtain secondary synchronization signals S1 and S2 to be detected respectively corresponding to two half-frames of the one frame time domain signal; carry out inner products on said S1 and S2 with SSC1—n and SSC2—n respectively to obtain [S1,SSC1—n], [S2,SSC2—n], [S1,SSC2—n], [S2,SSC1—n], then combine inner product results to obtain sets [S1,SSC1—n]+[S2,SSC2—n] and [S1,SSC2—n]+[S2,SSC1—n], let P1—n=P1—n−1+[S1,SSC1—n]+[S2,SSC2—n], P2—n=P2—n−1+[S1,SSC2—n]+[S2,SSC1—n], and send the P1—n and P2—n to a frame timing synchronization module, wherein P1—−1 and P2—−1 are empty sets;
the frame timing synchronization module, which is configured to: select a maximum value P of absolute values of correlation values in the P1—n and P2—n, and judge whether the maximum value P is greater than a preset threshold Tmax, and if yes, take the index of the maximum value P as an ID number of the cell group, and complete one frame timing synchronization by judging whether the maximum value occurs in P1—n or P2—n; if not, compare the absolute values of the correlation values in the P1—n and P2—n with a threshold Tccv, select the secondary synchronization sequences corresponding to the correlation value of which the absolute value is not less than the Tccv in the P1—n and P2—n as new secondary synchronization sequences SSC1—n and SSC2—n with the index being increased by 1 to send to the multiple-frame average module.

### Claim 8 (depends on 7)

The apparatus as claimed in claim 7, wherein said multiple-frame average module is further configured to:
compare the absolute values of the correlation values with a same cell group number in the P1—n and P2—n with the preset threshold Tccv, and if the absolute value of the correlation value corresponding to the same cell group number in the P1—n and P2—n is less than the Tccv, then discarding this cell group number.

### Claim 9 (depends on 7)

The apparatus as claimed in claim 7, wherein said local secondary synchronization sequence generation module is further configured to: carry out cross correlation on the received time domain signals and a local primary synchronization sequence, and obtain the sector number of the cell group by detecting a correlation peak.

### Claim 10 (depends on 7)

The apparatus as claimed in claim 7, wherein said multiple-frame average module is further configured to: for the received time domain signals of one frame, take use of a half frame timing synchronization result and blind detection to obtain a cyclic prefix mode, and at this time, demodulate said time domain signals by orthogonal frequency division multiplex (OFDM) to frequency domain to obtain said secondary synchronization signals S1 and S2 to be detected.

### Claim 11 (depends on 10)

The apparatus as claimed in claim 10, wherein said local secondary synchronization sequence generation module is further configured to: carry out cross correlation on the received time domain signals and a local primary synchronization sequence, and obtain said half frame timing synchronization result by detecting the correlation peak.