Impulse-based communication system

• US 20060018369A1
• Filed: 05/17/2005
• Published: 01/26/2006
• Est. Priority Date: 07/23/2004
• Status: Active Grant

• Current Assignee: Semiconductor Technology Academic Research Center
• Original Assignee: Semiconductor Technology Academic Research Center
• Inventors: Furukawa, Jun, Sanada, Yukitoshi
• Granted Patent: US 7,590,198 B2
• Time in Patent Office: Days
• US Class Current: 375/149
• CPC Class Codes: H04B 1/7095 Sliding correlator type
• CPC Class Codes: H04B 1/7183 Synchronisation

Abstract

To provide a synchronization acquisition method, for impulse-based communication, that can easily accomplish synchronization acquisition even in a multipath environment, and that eliminates the need to repeat synchronization acquisition even when transmit information changes, the synchronization acquisition method being implemented using: a code synchronizing correlator (21) which synchronizes received information with a first pulse signal having the same period as the transmit information transmitted from the transmitting end; a memory (211) in which, when the value representing the correlation between the received information and an unmodulated second pulse signal having the same period as the first pulse signal exceeds a predetermined threshold, the correlation value is stored together with its reception time; and a timing detecting correlator (22) which sequentially updates the contents of the memory with a new correlation value and its generation time when the new correlation value exceeds the correlation value stored in the memory, wherein synchronization between the received signal and the first pulse signal is established by determining the generation timing of the first pulse signal in the code synchronizing correlator (22) by using the time stored in the memory.

Claims

1. A receiver circuit for performing impulse-based communication, comprising:

a code synchronizing correlator which synchronizes received information with a first pulse signal that has the same period as a pulse signal modulated by a spreading code, and sent from a transmitting end, and is modulated by the same spreading code as the spreading code used at the transmitting end; and

a timing detecting correlator which synchronizes the received information with an unmodulated second pulse signal that has the same period as the first pulse signal but is shifted in time with respect to the first pulse signal by an amount equal to a time difference between the spreading code modulated pulse signal sent from the transmitting end and a timing detecting signal sent from the transmitting end, wherein

the timing detecting correlator measures correlation between the received signal and the second pulse signal at predetermined intervals of time that is longer than pulse spacing in the second pulse signal, the timing detecting correlator having a memory for storing a better correlation value together with reception time thereof, and

generation timing of the first pulse signal is determined by using the time difference and the reception time, while generation timing of the second pulse signal is determined by using the generation time, thus operating the timing detecting correlator in parallel with demodulation being performed by the code synchronizing correlator.

2. A receiver circuit as claimed in claim 1, wherein

the code synchronizing correlator comprises:

a first pulse generator which generates the first pulse signal;

a first multiplier which multiplies the received signal by an output of the first pulse generator;

demodulating means for recovering demodulated data from an output of the first multiplier; and

a first control circuit which controls the generation timing of the first pulse signal based on an output of the demodulating means, the time difference, and the reception time, and

the timing detecting correlator comprises;

a second pulse generator which generates the second pulse signal;

a second multiplier which multiplies the received signal by an output of the second pulse generator; and

a second control circuit which performs control so that the generation timing of the pulse to be output from the first pulse generator is shifted by an amount equal to the generation time stored in the memory.

3. A receiver circuit as claimed in claim 1, wherein the impulse-based communication is impulse-based UWB.

4. A receiver circuit as claimed in claim 1, wherein the transmit information is generated by using an information transmitting spreading code.

5. A receiver circuit as claimed in claim 4, wherein the information transmitting spreading code is an information transmitting PN code.

6. A receiver circuit as claimed in claim 4, wherein the information transmitting spreading code is an information transmitting Baker code.

7. A transmitting/receiving system for performing impulse-based communication, comprising a transmitter circuit and a receiver circuit, wherein

the transmitter circuit comprises:

a first pulse generator which generates transmit information as a pulse signal having a prescribed period;

a second pulse generator which generates a pulse detecting signal with the prescribed period;

a control circuit which controls the first pulse generator and the second pulse generator so that a time difference between the pulses output from the first and second pulse generators becomes equal to a predetermined value; and

an adder which adds the output of the first pulse generator to the output of the second pulse generator and outputs the resulting sum, and

the receiver circuit comprises;

a code synchronizing correlator which synchronizes received information with a first pulse signal that has the same period as a pulse signal modulated by a spreading code and sent from a transmitting end and that is modulated by the same spreading code as the spreading code used at the transmitting end; and

a timing detecting correlator which synchronizes the received information with an unmodulated second pulse signal that has the same period as the first pulse signal but is shifted in time with respect to the first pulse signal by an amount equal to a time difference between the spreading code modulated pulse signal sent from the transmitting end and a timing detecting signal sent from the transmitting end, wherein

the timing detecting correlator measures correlation between the received signal and the second pulse signal at predetermined intervals of time that is longer than pulse spacing in the second pulse signal, the timing detecting correlator having a memory for storing a better correlation value together with reception time thereof, and

generation timing of the first pulse signal is determined by using the time difference and the generation time, while generation timing of the second pulse signal is determined by using the generation time, thus operating the timing detecting correlator in parallel with demodulation being performed by the code synchronizing correlator.

8. A transmitting/receiving system as claimed in claim 7, wherein the impulse-based communication is impulse-based UWB.

9. A transmitting/receiving system as claimed in claim 7, wherein the transmit information is generated by using an information transmitting spreading code.

10. A transmitting/receiving system as claimed in claim 9, wherein the information transmitting spreading code is an information transmitting PN code.

11. A transmitting/receiving system as claimed in claim 9, wherein the information transmitting spreading code is an information transmitting Baker code.

12. A synchronization acquisition method for performing impulse-based communication, comprising:

generating, at a receiving end as well as at a transmitting end, a pulse detecting signal shifted in time by a predetermined amount with respect to transmit information of a pulse signal having a prescribed period;

establishing synchronization at the receiving end by using synchronization between the received transmit information and the pulse detecting signal; and

establishing synchronization between the received signal and the transmit information by generating the transmit information at the receiving end in such a manner as to be shifted in time by the predetermined amount with respect to the synchronized pulse detecting signal, wherein

the received information is synchronized with a first pulse signal that has the same period as the pulse signal modulated by a spreading code and sent from the transmitting end and that is modulated by the same spreading code as the spreading code used at the transmitting end,

the received information is synchronized with an unmodulated second pulse signal that has the same period as the first pulse signal but is shifted in time with respect to the first pulse signal by an amount equal to a time difference between the spreading code modulated pulse signal sent from the transmitting end and a timing detecting signal sent from the transmitting end,

when synchronizing the received information with the unmodulated second pulse signal, correlation between the received signal and the second pulse signal is measured at predetermined intervals of time that is longer than pulse spacing in the second pulse signal, and a better correlation value and reception time thereof are paired together and stored in a memory, and

generation timing of the first pulse signal is determined by using the time difference and the reception time, while generation timing of the second pulse signal is determined by using the reception time, thus operating a timing detecting correlator in parallel with demodulation being performed by a code synchronizing correlator, and thereby establishing synchronization between the received signal and the first pulse signal.

13. A synchronization acquisition method as claimed in claim 12, wherein the impulse-based communication is impulse-based UWB.

14. A synchronization acquisition method as claimed in claim 12, wherein the transmit information is generated by using an information transmitting spreading code.

15. A synchronization acquisition method as claimed in claim 14, wherein the information transmitting spreading code is an information transmitting PN code.

16. A synchronization acquisition method as claimed in claim 14, wherein the information transmitting spreading code is an information transmitting Baker code.

17. A synchronization acquisition method as claimed in claim 12, wherein the transmit information is a DS-modulated code comprising a sequence of inverted and non-inverted pulses.

18. A synchronization acquisition method as claimed in claim 12, wherein the transmit information is a TH-modulated code in which each pulse phase is shifted or not shifted by a predetermined amount of time.