Apparatus for measuring multipath propagation characteristics

• US 5,710,977 A
• Filed: 06/07/1995
• Issued: 01/20/1998
• Est. Priority Date: 08/31/1994
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Nakazawa, Isao
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): BANKS HAROLD, MARSHA DENISE
• Application Number:
  US08/472,397
• Time in Patent Office: 958 Days
• Field of Search: 455/52.1, 455/52.3, 455/65, 455/67.3, 455/54.1
• US Class Current: 455/65
• CPC Class Codes: H04B 1/1081 Reduction of multipath noise by equalising H04B7/005
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 17/391 Modelling the propagation channel
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04

Abstract

An apparatus for measuring multipath propagation characteristics receives a plurality of transmitted waves propagated over a plurality of different propagation paths and subjected to multipath fading over the propagation paths, and measures multipath propagation characteristics with respect to those propagation paths based on the received waves. The multipath propagation characteristics can be measured relative to a plurality of propagation path systems using the same frequency band. The apparatus for measuring multipath propagation characteristics comprises a plurality of transmitters located in different spatial positions, respectively, and a receiver for receiving a plurality of waves transmitted from the transmitters while the receiver is moving. The transmitters generate respective waves to be transmitted that each comprise a plurality of discrete spectral components which are arranged in the frequency domain such that they do not overlap each other in the same frequency band. The receiver simultaneously receives the waves which have been transmitted from the respective transmitters and each propagated over a plurality of different propagation routes or paths while being subjected to multipath fading, and measures multipath propagation characteristics relative to the propagation paths based on the received waves.

Claims

1. An apparatus for measuring multipath propagation characteristics based on a plurality of received transmitted waves that have been propagated over a plurality of different propagation paths while being subjected to multipath fading, comprising:

a plurality of transmitters located in different spatial positions, respectively, for generating respective waves to be transmitted that each comprise a plurality of discrete spectral components which are arranged in the frequency domain such that they do not overlap each other in the same frequency band; and

a movable receiver for simultaneously receiving the waves which have been transmitted from said respective transmitters and each propagated over a plurality of different propagation paths while being subjected to multipath fading, and measuring multipath propagation characteristics relative to the paths based on the received waves.

2. An apparatus according to claim 1, wherein each of said transmitters comprises:

dispersing signal generating means for generating dispersive signal;

modulating means for modulating carrier with the dispersive signal generated by said dispersing signal generating means; and

radiating means for radiating the carrier modulated by said modulating means into space.

3. An apparatus according to claim 1, wherein said movable receiver comprises:

receiving means for simultaneously receiving the waves transmitted from said transmitters, respectively;

converting means for converting the received waves into spectrums in the frequency domain; and

analyzing means for analyzing multipath propagation characteristics based on said spectrums.

4. An apparatus according to claim 1, wherein each of said transmitter comprises:

dispersive signal generating means for generating dispersive signal;

modulating means for modulating carrier having a frequency different from frequencies which carriers of the other modulating means have with the dispersive signal generated by said dispersing signal generating means; and

radiating means for radiating the carrier modulated by said modulating means into space.

5. An apparatus according to claim 1, wherein said transmitters comprise:

means for transmitting the waves such that all the spectral components thereof are discretely arranged in the frequency domain so as not to overlap each other.

6. An apparatus according to claim 1, wherein said movable receiver comprises:

receiving means for simultaneously receiving the waves transmitted from said transmitters, respectively;

converting means for converting the received waves into spectrums in the frequency domain;

removing means for removing from the spectrums those spectral components of the spectrums which are spaced at frequency intervals smaller than a predetermined frequency interval, and outputting an output signal indicative of the spectrums from which those spectral components have been removed; and

analyzing means for analyzing multipath;

. propagation characteristics based on said output signal from said removing means.

7. An apparatus according to claim 1, wherein each of said transmitters comprises:

dispersive signal generating means for generating dispersive signal, at the same time interval as the other dispersive signal generating means;

modulating means for modulating carrier having a frequency different from frequencies which carriers of the other modulating means have with the dispersive signal generated by said dispersing signal generating means; and

radiating means for radiating the carrier modulated by said modulating means into space.

8. An apparatus according to claim 1, wherein said movable receiver comprises:

direct receiving means for directly receiving the waves transmitted from said transmitters, respectively, not via the propagation paths;

first converting means for converting the directly received waves into spectrums in the frequency domain;

memory means for storing the spectrums produced by said first converting means;

receiving means for simultaneously receiving the waves transmitted from said transmitters, respectively, and propagated over the propagation paths;

second converting means for converting the waves received by said receiving means into a spectrum in the frequency domain; and

analyzing means for correcting the spectrums produced by said second converting means with the spectrums stored by said memory means, and analyzing multipath propagation characteristics based on the corrected spectrums.

9. An apparatus according to claim 1, wherein said movable receiver comprises:

selective control means for producing an output signal to control selection of one, at a time, of a plurality of reception bands;

receiving means for selecting one, at a time, of a plurality of reception bands thereof in response to the output signal from said selective control means, and simultaneously receiving the waves transmitted from said transmitters, respectively, in said selected one of the reception bands;

converting means for converting the received waves into spectrums in the frequency domain; and

analyzing means for analyzing multipath propagation characteristics based on said spectrums.

10. An apparatus according to claim 1, wherein said movable receiver comprises:

receiving means for simultaneously receiving the waves transmitted from said transmitters, respectively;

converting means for converting the received waves into spectrums in the frequency domain; and

analyzing means for calculating electric power values and phases of the respective spectral components based on said spectrums thereby to analyze multipath propagation characteristics.

11. An apparatus according to claim 1, wherein said movable receiver comprises:

receiving means for simultaneously receiving the waves transmitted from said transmitters, respectively;

converting means for converting the received waves into spectrums in the frequency domain;

vector synthesizing means for calculating electric power values and phases of the respective spectral components based on said spectrums, and synthesizing vectors of the respective received waves; and

analyzing means for determining carrier phase rotation characteristics of the received waves based on the vectors synthesized by said vector synthesizing means.

12. An apparatus according to claim 1, wherein said movable receiver comprises:

receiving means for simultaneously receiving the waves transmitted from said transmitters, respectively;

converting means for converting the received waves into spectrums in the frequency domain;

correcting means for correcting said spectrums for a processing time required by said converting means;

vector synthesizing means for calculating electric power values and phases of the respective spectral components based on said spectrums corrected by said correcting means thereby to synthesize vectors of the respective received waves; and

analyzing means for analyzing multipath propagation characteristics based on the vectors which are synthesized a plurality of times by said vector synthesizing means.

13. An apparatus according to claim 1, wherein said movable receiver comprises:

memory means for previously storing electric power values in the frequency domain and corrective values for phases of the waves transmitted from said transmitters;

receiving means for simultaneously receiving the waves transmitted from said transmitters, respectively, over the propagation paths;

converting means for converting the received waves into spectrums in the frequency domain; and

analyzing means for correcting said spectrums with the electric power values and corrective values for phases which are stored by said memory means, and analyzing multipath propagation characteristics based on the corrected spectrums.

14. An apparatus according to claim 1, wherein said movable receiver comprises:

receiving means for simultaneously receiving the waves transmitted from said transmitters, respectively;

converting means for converting the received waves into spectrums in the frequency domain; and

analyzing means for analyzing self frequency correlations of the received waves based on said spectrums.

15. An apparatus according to claim 1, wherein said movable receiver comprises:

receiving means for simultaneously receiving the waves transmitted from said transmitters, respectively;

converting means for converting the received waves into spectrums in the frequency domain; and

analyzing means for determining a desired-to-undesired power ratio, a carrier-to-noise power ratio, and a transfer function or an amplitude notch in a transmission hand, based on said spectrums, and estimating the transmitted quality of the received waves based on the desired-to-undesired power ratio, the carrier-to-noise power ratio, and the transfer function or the amplitude notch in the transmission band which have been determined.

16. An apparatus according to claim 1, wherein said movable receiver comprises:

a plurality of antennas having respective directivity patterns and three-dimensionally installed such that a directivity pattern composed of a combination of said directivity patterns has a wide angle;

a plurality of receiving means connected respectively to said antennas for simultaneously receiving the waves transmitted from said transmitters, respectively;

a plurality of frequency shifting means connected to said receiving means, respectively, for shifting frequencies of the received waves by respective different degrees;

combining means for combining the received waves whose frequencies have been shifted by said frequency shifting means;

converting means for converting an output signal from said combining means into a spectrum in the frequency domain; and

analyzing means analyzing multipath propagation characteristics based on said spectrum.

17. An apparatus according to claim 1, wherein said transmitters comprise:

respective dispersive signal generating means for generating dispersive signals, respectively;

respective modulating means for modulating respective carriers with the dispersive signals generated by said dispersing signal generating means, respectively;

respective radiating means for radiating the carriers modulated by said modulating means into space, respectively;

frame synchronizing means for synchronizing frames of the dispersive signals generated by said dispersing signal generating means; and

wherein said movable receiver comprises;

receiving means for receiving the waves transmitted from said transmitters, respectively;

frame timing detecting means for detecting the respective timing of frames of the received waves; and

analyzing means for analyzing absolute delay times from said transmitters and relative delay times between said transmitters based on the detected timing of the frames of the received waves.

18. An apparatus according to claim 17, wherein said frame synchronizing means comprises frame synchronizing signal delivering means for delivering a frame synchronizing signal to said transmitters, and said dispersive signal generating means comprise respective means for generating dispersive signals in synchronism with the frames based on said frame synchronizing signal.