Wireless communication device, wireless communication system, and method for detecting receive timing of direct wave

• US 20100246637A1
• Filed: 03/31/2010
• Published: 09/30/2010
• Est. Priority Date: 03/31/2009
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Miyatani, Tetsuhiko
• Granted Patent: US 8,351,547 B2
• Time in Patent Office: Days
• US Class Current: 375/130
• CPC Class Codes: H04J 11/0063 of multipath interference, e.g. Rake receivers
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0216 with estimation of channel length
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 27/2636 with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• CPC Class Codes: H04L 27/26526 with inverse FFT [IFFT] or inverse DFT [IDFT] demodulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] receiver or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 27/2676 Blind, i.e. without using known symbols
• CPC Class Codes: H04L 5/0023 Time-frequency-space

Abstract

A wireless communication device and method are capable of detecting a receive timing of a direct wave at higher precision without increasing transmit power. A signal receiver receives a signal having a center frequency changed in a predetermined rule at predetermined time intervals. A time-frequency transformer transforms the received signal from a time domain to a frequency domain. A filter removes frequency-domain signal components unused during reception, based on the predetermined rule, from the frequency-domain signal. A reverse modulator performs a reverse modulation process on the remaining signal components. A signal adder generates an added signal by performing accumulative addition on the signal components that underwent the reverse modulation process in the reverse modulator for a predetermined period. A direct wave arrival time determiner determines an arrival time of a direct wave according to an impulse response obtainable from an output of the frequency-time transformer.

Claims

1. A wireless communication device comprising:

a signal receiver configured to receive a signal comprising a center frequency that is changed in a predetermined rule at intervals of a predetermined time;

a time-frequency transformer configured to transform an output of the signal receiver to a frequency-domain signal;

an unused-domain component removing filter configured to remove frequency-domain signal components unused during reception, based on the predetermined rule, from the frequency-domain signal;

a signal adder configured to generate an added signal by performing accumulative addition on the remaining signal components that have passed through the unused-domain component removing filter for a predetermined period;

a frequency-time transformer configured to transform the added signal from the frequency domain to the time domain; and

a direct wave arrival time determiner configured to determine an arrival time of a direct wave according to an impulse response based on an output signal from the frequency-time transformer.

2. The wireless communication device of claim 1, further comprising a Multi-Path Interference Canceller (MPIC) configured to cancel multipath interference components included in the impulse response.

3. The wireless communication device of claim 1, further comprising an in-phase addition-averaging unit configured to perform in-phasing on a pertinent impulse response based on a phase of a direct wave temporarily detected by removing multipath interference components from the impulse response, and average the impulse response for a predetermined time.

4. The wireless communication device of claim 3, further comprising a Multi-Path Interference Canceller (MPIC) configured to cancel multipath interference components included in the impulse response.

5. The wireless communication device of claim 1, further comprising a correlator configured to:

perform an autocorrelation operation to determine the impulse response; and

calculate a delay profile from the impulse response.

6. The wireless communication device of claim 1, further comprising:

a multiplier configured to multiply an added signal by one of a pilot signal and a multiplication coefficient based on a transmission data signal.

7. A wireless terminal comprising:

a frequency changer configured to change a center frequency of a transmission signal in a predetermined rule at intervals of a predetermined time; and

a signal transmitter configured to transmit a signal at the center frequency changed by the frequency changer, the signal transmitted to a wireless communication device configured to detect a receive timing of a direct wave.

8. The wireless terminal of claim 7, wherein the frequency changer is further configured to change a plurality of center frequencies distributed on a frequency axis at regular intervals, in the predetermined rule while maintaining the predetermined interval, and the signal transmitter is further configured to transmit the signal at the plurality of center frequencies changed in the frequency changer.

9. The wireless terminal of claim 7, further comprising a plurality of transmit antennas configured to transmit the signal, wherein the signal transmitter simultaneously transmits the signal via the plurality of transmit antennas.

10. The wireless terminal of claim 8, wherein the frequency changer is further configured to change a plurality of center frequencies distributed on a frequency axis at regular intervals, in the predetermined rule while maintaining the predetermined interval, and the signal transmitter is further configured to transmit the signal at the plurality of center frequencies changed in the frequency changer.

11. The wireless terminal of claim 7, further comprising:

an antenna switch configured to switch the transmit antennas that are used at the intervals of the predetermined time.

12. The wireless terminal of claim 11, wherein the signal transmitter simultaneously transmits the signal via the plurality of transmit antennas.

13. The wireless terminal of claim 12, wherein the frequency changer is further configured to change a plurality of center frequencies distributed on a frequency axis at regular intervals, in the predetermined rule while maintaining the predetermined interval, and the signal transmitter is further configured to transmit the signal at the plurality of center frequencies changed in the frequency changer.

14. A method for detecting a timing of a direct wave in a wireless communication device, comprising:

receiving a signal having a center frequency that is changed in a predetermined rule at intervals of a predetermined time;

transforming the received signal to a frequency-domain signal;

removing frequency-domain signal components unused during reception based on the predetermined rule from the frequency-domain signal;

performing a reverse modulation process on remaining signal components left after the unused-frequency-domain signal components are removed from the frequency domain signal;

generating an added signal by performing accumulative addition on the reverse-modulated signal components for a predetermined period;

transforming the added signal from the frequency domain to the time domain; and

determining an arrival time of the direct wave based on an impulse response obtainable from the added signal in the time domain.

15. The method of claim 14, further comprising:

performing an autocorrelation operation to determine the impulse response; and

calculating a delay profile from the impulse response.

16. The method of claim 14, further comprising canceling multipath interference components included in the impulse response.

17. The method of claim 14, further comprising:

performing in-phasing on a pertinent impulse response based on a phase of a direct wave temporarily detected by removing multipath interference components from the impulse response, and average the impulse response for the predetermined time; and

canceling multipath interference components included in the impulse response.

18. A method for detecting a timing of a direct wave in a wireless communication system, comprising:

changing a center frequency of a transmission signal in a predetermined rule at intervals of a predetermined time; and

transmitting a signal at the center frequency changed in the frequency change step, the signal transmitted to a wireless communication device configured to detect a receive timing of the direct wave.

19. The method of claim 18, further comprising:

changing a plurality of center frequencies distributed on a frequency axis at regular intervals, in the predetermined rule while maintaining the predetermined interval; and

transmitting the signal at the plurality of center frequencies.

20. The method of claim 19, further comprising:

transmitting the signal via a plurality of transmit antennas; and

switching the plurality of transmit antennas that are used at the intervals of the predetermined time.