Radio environment measuring system

• US 5,381,444 A
• Filed: 10/30/1992
• Issued: 01/10/1995
• Est. Priority Date: 10/31/1991
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Tajima, Masami
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US07/969,460
• Time in Patent Office: 802 Days
• Field of Search: 455/52.3, 455/54.1, 455/54.2, 455/56.1, 455/65, 455/67.1, 455/67.3, 455/67.4, 455/67.6, 455/33.1, 455/53.1, 375/1, 375/11-14, 380/38, 380/34, 342/118, 342/125, 379/58, 379/59
• US Class Current: 375/141
• CPC Class Codes: G01S 13/762 with special measures concerning the radiation pattern, e.g. S.L.S. aerials or aerial systems providing at least two radiation patterns, e.g. providing sum and difference patterns, H01Q25/00
• CPC Class Codes: G01S 13/78 discriminating between different kinds of targets, e.g. IFF-radar, i.e. identification of friend or foe G01S13/75, G01S13/79 take precedence
• CPC Class Codes: H04L 25/0202 Channel estimation

Abstract

A radio environment measuring system for measuring a propagation state of radio waves includes: a fixed radio apparatus provided in a base station; a mobile radio apparatus operatively connected to the fixed radio apparatus through the radio waves; the mobile radio apparatus having a repeater unit for receiving a transmission signal from the fixed radio apparatus and sending a returned signal to the fixed radio apparatus; and the fixed radio apparatus having a transmission/reception unit for sending the transmission signal to the mobile radio apparatus and receiving the returned signal from the mobile radio apparatus, and a measuring unit for measuring the propagation state of the radio waves, for example, a propagation distance, direction and reception intensity of the radio waves between the fixed radio apparatus and the mobile radio apparatus based on the transmission signal and the returned signal.

Claims

1. A radio wave environment measuring system for measuring propagation state of radio waves, comprising:

a fixed radio apparatus provided in a base station; and

a mobile radio apparatus in communication with the fixed radio apparatus through the radio waves,

the mobile radio apparatus having a transmission/reception means for receiving a transmission signal from the fixed radio apparatus and for sending a return signal to the fixed radio apparatus, and

the fixed radio apparatus having a transmission/reception means for sending the transmission signal to the mobile radio apparatus and for receiving the returned signal from the mobile radio apparatus, and a measuring means for determining the propagation state of radio wave, wherein the propagation state of the radio waves includes at least one of a propagation distance, direction and reception intensity of the radio waves between the fixed radio apparatus and the mobile radio apparatus based on the transmission signal and the returned signal.

2. A radio wave environment measuring system as claimed in claim 1, wherein the transmission/reception means of the fixed radio apparatus comprises a repeater means for receiving the returned signal and again sending the returned signal to the mobile radio apparatus, and the transmission/reception means of the mobile radio apparatus also comprises a repeater means for sending the returned signal to the fixed radio apparatus, and wherein one of the transmission and the reception of the transmission and returned signals are performed for predetermined times between the fixed radio apparatus and the mobile radio apparatus.

3. A radio wave environment measuring system as claimed in claim 2, wherein the measuring means determines the propagation state of the radio waves based on the first transmission signal and the returned signal after one of the transmission and the reception for predetermined times.

4. A radio wave environment measuring system as claimed in claim 1, wherein the fixed radio apparatus further comprises a non-directional antenna and a directional antenna.

5. A radio wave environment measuring system as claimed in claim 1, wherein the transmission/reception means of the fixed radio apparatus further comprises a side lobe compression means for deciding a reception signal based on a main lobe when the reception intensity of the directional antenna is larger than that of the non-directional antenna.

6. A radio wave environment measuring system as claimed in claim 1, wherein the transmission/reception means of the fixed radio apparatus further comprises a sweep means for switching the frequency of the transmission signal and sweeping the frequency, and wherein the measuring means measures the propagation state of the radio waves based on change of the phase difference between the transmission signal and the returned signal.

7. A radio wave environment measuring system as claimed in claim 1, wherein the transmission/reception means of the fixed radio apparatus further comprises a transmission means for sending a transmission signal modulated by codes having large autocorrelation, correlation, and wherein the measuring means measures the propagation state based on the auto-correlation for the demodulated codes which are obtained by the returned signal from the mobile radio apparatus.

8. A radio wave environment measuring system as claimed in claim 1, wherein the transmission/reception means of the mobile radio apparatus further comprises a delay circuit for delaying the returned signal based on an instruction from the fixed radio apparatus.

9. A radio wave environment measuring system as claimed in claim 1, wherein the measuring means of the fixed radio apparatus further comprises a square-composition means for obtaining the phase difference between the returned signal and a reference carrier having a 90 degree phase difference, and squaring the phase difference signal to obtain a composition signal.

10. A radio wave environment measuring system as claimed in claim 1, wherein the transmission/reception means of the fixed radio apparatus further comprises a dispersive delay line DDL and a pulse oscillator for generating linear frequency modulated pulses in the transmission means, and a limit amplifier LIM and a dispersive delay line for demodulating in the reception means, and wherein the mobile radio apparatus further comprises a frequency converter and a limit amplifier.

11. A radio wave environment measuring system as claimed in claim 10, wherein:

the fixed radio apparatus generates a transmission signal similar to a radar radio wave from the pulse oscillator, performs linear frequency modulation to obtain a spectrum-spread pulse for a time axis based on the dispersive delay line, and sends the spectrum-spread pulse to the mobile radio apparatus;

the mobile radio apparatus performs spectrum inversion based on the frequency-converted reception signal, and sends the returned signal to the fixed radio apparatus;

the fixed radio apparatus performs frequency conversion to obtain a linear-frequency modulated pulse having an opposite characteristic to the transmission signal, suppresses the modulated pulse based on the function of the pulse compression radar to concentrate the reflection energy spread for the time and frequency, and measures the propagation state of radio waves for every delay time from the start of the transmission of the radio waves by the fixed radio apparatus.

12. A radio wave environment measuring system as claimed in claim 10, wherein each of the limit amplifiers in the fixed and mobile radio apparatuses has the function for suppressing the amplitude of an interference wave, and the above amplitude-limited interference waves are spread by the pulse compression function for the time and frequency.