METHOD, APPARATUS AND SYSTEM FOR DETECTING RANDOM ACCESS SIGNAL

• US 20170201397A1
• Filed: 08/27/2014
• Published: 07/13/2017
• Est. Priority Date: 06/18/2014
• Status: Active Grant

• Current Assignee: Xi'An Zhongxing New Software Co., Ltd. (ZTE Corporation)
• Original Assignee: ZTE Corporation
• Inventors: WANG, Wenfang, WANG, Shaopeng, QIN, Hongfeng
• Granted Patent: US 10,033,559 B2
• Time in Patent Office: Days
• CPC Class Codes: H04J 11/004 using regenerative subtractive interference cancellation
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 25/085 Arrangements for reducing interference in line transmission systems, e.g. by differential transmission
• CPC Class Codes: H04L 27/26 Systems using multi-frequency codes H04L27/32 takes precedence
• CPC Class Codes: H04L 27/2663 Coarse synchronisation, e.g. by correlation
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

A method for detecting a random access signal includes: determining a temporary peak detection sequence according to a received time domain random access signal; determining an interference cancellation weight for a frequency domain cyclic shift sequence corresponding to a search window in the temporary peak detection sequence, and performing interference cancellation on the temporary peak detection sequence according to the interference cancellation weight, obtaining a final peak detection sequence; and performing peak detection on the final peak detection sequence. An apparatus and system for detecting a random access signal are also described.

Claims

1. A method for detecting a random access signal, comprising:

determining a temporary peak detection sequence according to a received time domain random access signal;

determining an interference cancellation weight for a frequency domain cyclic shift sequence corresponding to a search window in the temporary peak detection sequence, and performing interference cancellation on the temporary peak detection sequence according to the interference cancellation weight, obtaining a final peak detection sequence; and

performing peak detection on the final peak detection sequence.

2. The method according to claim 1, wherein, said determining a temporary peak detection sequence according to a received time domain random access signal comprises:

transforming the received time domain random access signal from time domain to frequency domain through fast fourier transform FFT, obtaining a frequency domain random access signal;

performing a conjugate dot product on the frequency domain random access signal and a frequency domain value of a local root sequence or a cyclic shift sequence; and

then, transforming the frequency domain random access signal from the frequency domain to the time domain through inverse fast fourier transform IFFT, obtaining a temporary peak detection sequence.

3. The method according to claim 2, wherein, the temporary peak detection sequence is a temporary peak detection sequence of the local root sequence or a temporary peak detection sequence of the cyclic shift sequence.

4. The method according to claim 1, wherein, said determining interference cancellation weights for a frequency domain cyclic shift sequence corresponding to a search window in the temporary peak detection sequence and performing interference cancellation on the temporary peak detection sequence according to the interference cancellation weight, obtaining a final peak detection sequence specifically comprises:

determining the interference cancellation weight corresponding to the frequency domain cyclic shift sequence in turn for the frequency domain cyclic shift sequence corresponding to the search window in the temporary peak detection sequence, and then performing weighted combination and then computing modular square on the temporary peak detection sequence according to the interference cancellation weight, obtaining the final peak detection sequence.

5. The method according to claim 1, wherein, said performing the peak detection on the final peak detection sequence specifically comprises:

performing a noise mean estimation on the final peak detection sequence, and determining a signal detection threshold according to an obtained estimation value, then detecting a signal in the search window corresponding to a current frequency domain cyclic shift sequence, and filtering a signal exceeding the signal detection threshold.

6. The method according to claim 1, wherein, said determining the interference cancellation weight is specifically obtained according to formula W=R_SYR_YY⁻

1, wherein, W is the interference cancellation weight, R_SY=E{SY^H}, R_YY=E{YY^H}, S is a local frequency domain cyclic shift sequence, Y is a frequency domain random access signal before the interference cancellation, a dimension of S is 1×

N, a dimension of Y is M×

N, M is a number of receiving antennas, and N is a number of subcarriers.

7. The method according to claim 1, wherein, the interference cancellation is specifically obtained according to Ŷ

=WY, wherein, W is the interference cancellation weight, Ŷ

is a frequency domain random access signal after the interference cancellation, and a dimension of Ŷ

is 1×

N.

8. The method according to claim 1, wherein, said performing the peak detection on the final peak detection sequence comprises:

performing power combination first on a final peak detection sequence of which a random access signal is in a repeat format, then performing a noise mean estimation on a combined final peak detection sequence, and determining a signal detection threshold according to an obtained estimation value, then detecting a signal in the search window corresponding to a current frequency domain cyclic shift sequence, and filtering a signal exceeding the signal detection threshold.

9. The method according to claim 8, wherein, the power combination is an equal gain combination or a maximum ratio combination.

10. The method according to claim 1, wherein, said determining an interference cancellation weight for a frequency domain cyclic shift sequence corresponding to a search window in the temporary peak detection sequence and performing interference cancellation on the temporary peak detection sequence according to the interference cancellation weight, obtaining a final peak detection sequence specifically comprises:

determining all interference cancellation weights corresponding to the frequency domain cyclic shift sequence according to the frequency domain cyclic shift sequence corresponding to all search windows in the temporary peak detection sequence, performing weighted combination and then computing modular square on signals in all search windows in the temporary peak detection sequence respectively according to the interference cancellation weight, obtaining the final peak detection sequence.

11. An apparatus for detecting a random access signal, comprising following modules:

an obtaining module, arranged to;

determine a temporary peak detection sequence according to a received time domain random access signal;

an interference cancellation module, arranged to;

determine an interference cancellation weight for a frequency domain cyclic shift sequence corresponding to a search window in the temporary peak detection sequence, and perform interference cancellation on the temporary peak detection sequence according to the interference cancellation weight, obtain a final peak detection sequence; and

a detection module, arranged to;

perform peak detection on the final peak detection sequence.

12. The detection apparatus according to claim 11, wherein, the obtaining module comprises:

a time-frequency conversion submodule, arranged to;

perform fast fourier transform FFT on a received time domain random access signal, and obtain a frequency domain random access signal;

a cross correlation submodule, arranged to;

perform a conjugate dot product on the frequency domain random access signal with a frequency domain value of a local root sequence or a cyclic shift sequence; and

a frequency-time conversion submodule, arranged to;

perform inverse fast fourier transform IFFT on an output result of the cross correction submodule, and obtain a temporary peak detection sequence.

13. The detection apparatus according to claim 11, wherein, the interference cancellation module comprises:

a weight obtaining submodule, arranged to;

determine an interference cancellation weight for a frequency domain cyclic shift sequence corresponding to a search window in the temporary peak detection sequence; and

an operation submodule, arranged to;

perform weighted combination and then compute modular square on the temporary peak detection sequence according to an output result of the weight obtaining submodule, and obtain the final peak detection sequence.

14. The detection apparatus according to claim 11, wherein, the detection module further comprises:

a combination submodule, arranged to;

when the random access signal is a random access signal in a repeat format, perform power combination on the final peak detection sequence corresponding to two repeated parts.

15. A system for detecting a random access signal, comprising a terminal and a base station, wherein, the base station comprises an apparatus for detecting a random access signal of claim 11.

16. A system for detecting a random access signal, comprising a terminal and a base station, wherein, the base station comprises an apparatus for detecting a random access signal of claim 12.

17. A system for detecting a random access signal, comprising a terminal and a base station, wherein, the base station comprises an apparatus for detecting a random access signal of claim 13.

18. A system for detecting a random access signal, comprising a terminal and a base station, wherein, the base station comprises an apparatus for detecting a random access signal of claim 14.