RECEIVER, RECEIVING METHOD, AND NON-TRANSITORY COMPUTER READABLE MEDIUM

• US 20170163457A1
• Filed: 02/24/2015
• Published: 06/08/2017
• Est. Priority Date: 06/30/2014
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: ISHII, Naoto, FUTATSUGI, Yasunori
• Granted Patent: US 9,906,389 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 1/16 Circuits
• CPC Class Codes: H04L 1/005 Iterative decoding, including iteration between signal detection and decoding operation
• CPC Class Codes: H04L 25/0307 using blind adaptation
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• CPC Class Codes: H04L 27/2665 Fine synchronisation, e.g. by positioning the FFT window
• CPC Class Codes: H04L 27/2666 Acquisition of further OFDM parameters, e.g. bandwidth, subcarrier spacing, or guard interval length
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT

Abstract

The object of the present invention is to reduce the number of complex multiplications in an ICI reduction processing and to reduce the influence of characteristic degradation due to a quantization bit limitation of a digital signal processing. A receiver includes an extended CP addition unit (102) that receives radio signals through a plurality of paths and compensates for a symbol lost within a Fourier transform window to received signals received through the plurality of paths; and FFTs (104-1 and 104-2) each of which performs, in a range of the Fourier transform window, Fourier transform on the received signal with a lost symbol added.

Claims

1. A receiver, comprising:

an adding unit configured to compensate for a symbol lost within a Fourier transform window to received signals received through a plurality of paths; and

a Fourier transform unit configured to perform, in a range of the Fourier transform window, Fourier transform on a received signal with a lost symbol added in the addition unit.

2. The receiver according to claim 1, further comprising

a CP interval-outside selection unit configured to select, from among channel estimation values of the received signals received through the plurality of paths, a channel estimation value with a timing delay equal to or large than a cyclic prefix length from a head timing of the Fourier transform window;

and

an extended CP replica generation unit configured to generate a replica from a symbol replica of the received signal and the channel estimation value selected by the CP interval-outside selection unit, and cyclic-shift the replica within the Fourier transform window,

wherein the addition unit adds the replica generated and cyclic-shifted in the CP replica generation unit to the received signal, and

the Fourier transform unit performs Fourier transform on a received signal with the replica added within a range of the Fourier transform window.

3. The receiver according to claim 2,

wherein the extended CP replica generation unit includes

an end elimination unit configured to eliminate a CP length portion from an end of the symbol replica.

a convolution multiplication unit configured to convolution-multiply the channel estimation value selected in the CP interval-outside selection unit and the symbol replica with its end eliminated together,

an extended CP replica selection unit configured to select a portion of an interval-outside signal of the Fourier transform window from among a signal obtained in the convolution multiplication unit, and

an extended CP replica shift unit configured to shift a signal of the portion selected in the extended CP replica selection unit to a head timing of the Fourier transform window,

wherein the addition unit adds a signal shifted in the extended CP replica shift unit to the received signal.

4. The receiver according to claim 3, further comprising

an equalization filtering unit configured to perform channel equalization on a received signal subjected to Fourier transform in the Fourier transform unit,

a demodulation unit configured to perform soft decision on a received signal subjected to the channel equalization for each bit and obtain soft decision information,

a decoding unit configured to perform error correction decoding on the soft decision information,

a symbol replica generation unit configured to generate a symbol replica from soft decision information after being decoded, and

an inverse Fourier transform unit configured to perform inverse Fourier transform on the symbol replica,

wherein the end elimination unit eliminates a CP length portion from an end of the symbol replica subjected to inverse Fourier transform.

5. The receiver according to claim 2, further comprising a window timing determination unit configured to determine a timing of the Fourier transform window to preform Fourier transform on the received signal,

wherein the extended CP replica generation unit includes

an end elimination unit configured to eliminate a CP length portion from an end of the symbol replica,

a multiplication unit configured to multiply a channel estimation value selected in the CP interval-outside selection unit and the symbol replica with its end eliminated together in channel path unit,

an extended CP replica selection unit configured to

compare a head timing of a path of a symbol of a received signal with a cyclic prefix eliminated and a timing of the Fourier transform window,

select a signal in the Fourier transform window from among a signal after multiplication output from the multiplication unit for a channel path in which a head timing of the path being positioned ahead of the timing of the Fourier transform window, and

select an interval-outside signal of the Fourier transform window from among a signal after multiplication output from the multiplication unit for a channel path in which a head timing of the path being positioned behind the timing of the Fourier transform window,

an extended CP replica shift unit configured to shift only a selected signal of a channel path in which a head timing of the path being positioned behind the timing of the Fourier transform window to a head timing within the Fourier transform window, for a signal selected for each channel path output from the extended CP replica selection unit,

a path addition unit configured to add a signal after extended CP replica shift for each channel path output from the extended CP replica shift unit in the channel path, an extended CP replica selection unit configured to select a portion of an interval-outside signal of the Fourier transform window from among a signal obtained in the multiplication unit;

an extended CP replica shift unit configured to shift a signal of the portion selected in the extended CP replica selection unit to a head timing of the Fourier transform window; and

a path addition unit configured to add a signal shifted in the extended CP replica shift unit in channel path unit,

wherein the addition unit adds a signal added in the path addition unit to the received signal, and

the Fourier transform unit performs Fourier transform on a received signal after the addition in a range of the Fourier transform window.

6. The receiver according to claim 5,

wherein the multiplication unit multiplies a channel estimation value of an interval-outside signal of the Fourier transform window and a part of one or more OFDM symbol replicas after end elimination in same interval or different intervals for each channel path, and

the extended CP replica shift unit shifts a signal obtained in the multiplication unit to a head position within the Fourier transform window in a channel path in which a head timing of the path is positioned behind a timing of the Fourier transform window.

7. The receiver according to claim 2, further comprising

an equalization filtering unit configured to perform channel equalization on a signal subjected to Fourier transform in the Fourier transform unit,

a residual multipath interference replica generation unit configured to generate a replica of a residual multipath interference component,

a residual multipath interference elimination unit configured to eliminate a residual multipath interference component from a signal subjected to the channel equalization using the replica of the residual multipath interference component,

an inverse Fourier transform unit configured to perform inverse Fourier transform on a signal equalized after the residual multipath interference elimination,

a demodulation unit configured to convert a signal after the inverse Fourier transform into soft decision information in bit unit,

a decoding unit configured to perform error correction decoding on the soft decision information,

a symbol replica generation unit configured to generate a symbol replica using soft decision information subjected to the error correction decoding, and

a second Fourier transform unit configured to perform Fourier transform on the symbol replica,

wherein the residual multipath interference replica generation unit generates a replica of the residual multipath interference component using a signal obtained by performing Fourier transform on a symbol replica.

8. A receiving method, comprising:

compensating for a symbol lost within a Fourier transform window to received signals received through a plurality of paths; and

performing, in a range of the Fourier transform window, Fourier transform on a received signal with a lost symbol added in the compensating for the symbol lost.

9. A non-transitory computer readable medium storing a receiving program, the receiving program comprising:

an adding step for compensating for a symbol lost within a Fourier transform window to received signals received through a plurality of paths; and

a Fourier transform step for performing, in a range of the Fourier transform window, Fourier transform on a received signal with a lost symbol added in the addition step, and outputting a signal after transform.