Radio apparatus carrying out automatic gain control and gain control method

Abstract

A fading rate of a mobile terminal unit is estimated by a fading rate estimation unit and an optimum step constant is decided by a step constant determiner depending on the estimated fading rate. This step constant is fed back to a feedback data calculator, so that a reception level can be converged to an ideal level even under a fading environment and the like.

1. A radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising:
 a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal;  
 a fading rate estimation unit estimating a fading rate of the mobile terminal unit; and  
 a step constant determiner determining an optimum step constant which decides a gain of said gain control feedback circuit depending on the fading rate estimated by said fading rate estimation unit, wherein 
 said gain control feedback circuit includes a feedback data calculator calculating feedback data which defines a gain of said gain control feedback circuit based on said signal level and the optimum step constant as determined by said step constant determiner.  
 
 
     
     
       2. The radio apparatus according to  claim 1 , wherein
 said fading rate estimation unit calculates a reception response vector of the signal from the mobile terminal unit and estimates a fading rate from a correlation value of said reception response vectors between frames.  
 
     
     
       3. The radio apparatus according to  claim 1 , wherein
 said step constant determiner decides an optimum step constant at the fading rate estimated by said fading rate estimation unit based on an association table of preliminarily obtained fading rates and step constants.  
 
     
     
       4. The radio apparatus according to  claim 1 , wherein
 said feedback data calculator calculates feedback data in a next frame by obtaining a value of difference between a value of said signal level and an ideal value, dividing the value of difference by a prescribed constant a number of times corresponding to said step constant, followed by multiplication by a prescribed coefficient, thereby calculating an amount of change in feedback data, and adding the amount of change to feedback data at the time of receiving a previous frame.  
 
     
     
       5. A radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising:
 a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal;  
 a received signal strength detection unit detecting a received signal strength of the signal from the mobile terminal unit, at an antenna end of said radio apparatus;  
 a feedback data conversion unit carrying out conversion from the received signal strength detected by said received signal strength detection unit to optimum feedback data which decides a gain of said gain control feedback circuit based on an association table of preliminary obtained received signal strength and feedback data; and  
 a feedback data switch unit selecting the optimum feedback data converted by said feedback data conversion unit as an initial value of feedback data of said gain control feedback circuit.  
 
     
     
       6. A radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising:
 a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal,  
 said gain control feedback circuit including 
 a first gain control circuit supplying first feedback data allowing the level of said signal to converge to an ideal value slowly, and  
 a second gain control circuit supplying second feedback data allowing the level of said signal to converge to an ideal value fast;  
 
 a received signal strength detection unit detecting a received signal strength of the signal from the mobile terminal unit at an antenna end of said radio apparatus; and  
 a feedback data switch unit selecting said first feedback data or said second feedback data depending on a detection result from said received signal strength detection unit.  
 
     
     
       7. The radio apparatus according to  claim 6 , wherein
 said feedback data switch unit makes a switch from said first feedback data to said second feedback data when fluctuation of the received signal strength detected by said received signal strength detection unit decreases to a prescribed threshold or below or increases to a prescribed threshold or above.  
 
     
     
       8. A radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising:
 a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal,  
 said gain control feedback circuit including 
 a first gain control circuit supplying first feedback data allowing the level of said signal to converge to an ideal value slowly, and  
 a second gain control circuit supplying second feedback data allowing the level of said signal to converge to an ideal value fast;  
 
 a new terminal detector detecting whether a signal is received from a new mobile terminal unit; and  
 a feedback data switch unit selecting said first feedback data or said second feedback data depending on a detection result from said new terminal detector.  
 
     
     
       9. The radio apparatus according to  claim 8 , wherein
 said new terminal detector includes 
 a demodulation circuit demodulating a specific signal from a new mobile terminal unit, and  
 an error determiner determining whether an error exists in the signal demodulated by said demodulation circuit and if no error exists, determining that a signal is received from a new mobile terminal unit.  
 
 
     
     
       10. The radio apparatus according to  claim 9 , wherein
 said error determiner determines that a signal is received from a new mobile terminal unit if a unique word error does not exist in the signal demodulated in said demodulation circuit.  
 
     
     
       11. The radio apparatus according to  claim 9 , wherein
 said error determiner determines that a signal is received from a new mobile terminal unit if the number of bit errors in a preamble portion is equal to or smaller than a prescribed threshold in the signal demodulated in said demodulation circuit.  
 
     
     
       12. The radio apparatus according to any of claims  1 ,  5 ,  6 , or  8 , wherein
 said gain control feedback circuit includes a reception level detection unit detecting the level of said signal, and  
 said reception level detection unit calculates an amplitude value for each IQ signal during a prescribed period of a received signal and regards a maximum amplitude value among said amplitude values as a reception level of said received signal.  
 
     
     
       13. The radio apparatus according to any of claims  1 ,  5 ,  6 , or  8 , wherein
 said gain control feedback circuit includes a reception level detection unit detecting the level of said signal, and  
 said reception level detection unit calculates an amplitude value for each IF signal during a prescribed period of a received signal and regards a maximum amplitude value among said amplitude values as a reception level of said received signal.  
 
     
     
       14. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising the steps of:
 performing automatic gain control on said signal depending on a level of said signal;  
 estimating a fading rate of the mobile terminal unit; and  
 determining an optimum step constant which decides a gain of said automatic gain control, depending on said estimated fading rate, wherein 
 said step of carrying out automatic gain control includes the step of calculating feedback data which defines a gain of said automatic gain control, depending on said signal level and said optimum step constant as determined.  
 
 
     
     
       15. The gain control method according to  claim 14 , wherein
 said step of estimating a fading rate includes the step of calculating a reception response vector of the signal from the mobile terminal unit and estimating a fading rate from a correlation value of said reception response vectors between frames.  
 
     
     
       16. The gain control method according to  claim 14 , wherein
 said step of determining an optimum step constant includes the step of deciding an optimum step constant at said estimated fading rate based on an association table of preliminary obtained fading rates and step constants.  
 
     
     
       17. The gain control method according to  claim 14 , wherein
 said step of calculating feedback data includes the step of calculating feedback data in a next frame by obtaining a value of difference between a value of said signal level and an ideal value, dividing the value of difference by a prescribed constant a number of times corresponding to said step constant, followed by multiplication by a prescribed coefficient, thereby calculating an amount of change in feedback data, and adding the amount of change to feedback data at the time of receiving a previous frame.  
 
     
     
       18. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising the steps of:
 performing automatic gain control on said signal depending on a level of said signal;  
 detecting a received signal strength of the signal from the mobile terminal unit at an antenna end of said radio apparatus;  
 carrying out conversion from said detected, received signal strength to optimum feedback data which decides a gain of said automatic gain control based on an association table of preliminarily obtained received signal strengths and feedback data; and  
 selecting said converted optimum feedback data as an initial value of feedback data.  
 
     
     
       19. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising the steps of:
 performing automatic gain control on said signal depending on a level of said signal,  
 said step of performing automatic gain control including 
 a first step of supplying first feedback data allowing the level of said signal to converge to an ideal value slowly, and  
 a second step of supplying second feedback data allowing the level of said signal to converge to an ideal value fast;  
 
 detecting a received signal strength of the signal from the mobile terminal unit, at an antenna end of said radio apparatus; and  
 selecting said first feedback data or said second feedback data depending on a result of said detection.  
 
     
     
       20. The gain control method according to  claim 19 , wherein
 said step of selecting feedback data includes the step of making a switch from said first feedback data to said second feedback data when fluctuation of said detected, received signal strength decreases to a prescribed threshold or below or increases to a prescribed threshold or above.  
 
     
     
       21. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising the steps of:
 performing automatic gain control on said signal depending on a level of said signal,  
 said step of performing automatic gain control including 
 a first step of supplying first feedback data allowing the level of said signal to converge to an ideal value slowly, and  
 a second step of supplying second feedback data allowing the level of said signal to converge to an ideal value fast;  
 
 detecting whether a signal is received from a new mobile terminal unit; and  
 selecting said first feedback data or said second feedback data depending on a result of said detection.  
 
     
     
       22. The gain control method according to  claim 21 , wherein
 said step of detecting a new mobile terminal unit includes the steps of  
 demodulating a specific signal from a new mobile terminal unit, and  
 determining whether an error exists in the demodulated signal and if no error exists, determining that a signal is received from a new mobile terminal unit.  
 
     
     
       23. The gain control method according to  claim 22 , wherein
 said step of determining whether an error exists includes the step of determining that a signal has been received from a new mobile terminal unit when a unique word error does not exists in said demodulated signal.  
 
     
     
       24. The gain control method according to  claim 22 , wherein
 said step of determining whether an error exists includes the step of determining that a signal has been received from a new mobile terminal unit if the number of bit errors in a preamble portion is equal to or smaller than a prescribed threshold in said demodulated signal.  
 
     
     
       25. The gain control method according to any of claims  14 ,  18 ,  19 , or  21 , wherein
 said step of performing automatic gain control includes the step of detecting the level of said signal, and  
 said step of detecting the level of said signal has the step of calculating an amplitude value for each IQ signal during a prescribed period of a received signal and regarding a maximum amplitude value among said amplitude values as a reception level of said received signal.  
 
     
     
       26. The gain control method according to any of claims  14 ,  18 ,  19 , or  21 , wherein
 said step of performing automatic gain control includes the step of detecting the level of said signal, and  
 said step of detecting the level of said signal has the step of calculating an amplitude value for each IF signal during a prescribed period of a received signal and regarding a maximum amplitude value among said amplitude values as a reception level of said received signal.  
 
     
     
       27. A radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising:
   a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal;        a received signal strength detection unit detecting a received signal strength of the signal from the mobile terminal unit, at an antenna end of said radio apparatus;        a feedback data conversion unit carrying out conversion from the received signal strength detected by said received signal strength detection unit to optimum feedback data which decides a gain of said gain control feedback circuit based on preliminary obtained received signal strength and feedback data; and        a feedback data switch unit selecting the optimum feedback data converted by said feedback data conversion unit as an initial value of feedback data of said gain control feedback circuit.     
     
     
       28. A radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising:
   a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal;        a received signal strength detection unit detecting a received signal strength of the signal from the terminal unit, at an antenna end of said radio apparatus;        a feedback data conversion unit carrying out conversion from the received signal strength detected by said received signal strength detection unit to optimum feedback data which decides a gain of said gain control feedback circuit based on an association table of preliminary obtained received signal strength and feedback data; and        a feedback data switch unit selecting the optimum feedback data converted by said feedback data conversion unit as an initial value of feedback data of said gain control feedback circuit.     
     
     
       29. A radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising:
   a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal;        a received signal strength detection unit detecting a received signal strength of the signal from the mobile terminal unit, at said radio apparatus;        a feedback data conversion unit carrying out conversion from the received signal strength detected by said received signal strength detection unit to optimum feedback data which decides a gain of said gain control feedback circuit based on an association table of preliminary obtained received signal strength and feedback data; and        a feedback data switch unit selecting the optimum feedback data converted by said feedback data conversion unit as an initial value of feedback data of said gain control feedback circuit.     
     
     
       30. A radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising:
   a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal;        a received signal strength detection unit detecting a received signal strength of the signal from the terminal unit, at an antenna end of said radio apparatus;        a feedback data conversion unit carrying out conversion from the received signal strength detected by said received signal strength detection unit to optimum feedback data which decides a gain of said gain control feedback circuit based on preliminary obtained received signal strength and feedback data; and        a feedback data switch unit selecting the optimum feedback data converted by said feedback data conversion unit as an initial value of feedback data of said gain control feedback circuit.     
     
     
       31. A radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising:
   a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal;        a received signal strength detection unit detecting a received signal strength of the signal from the mobile terminal unit, at said radio apparatus;        a feedback data conversion unit carrying out conversion from the received signal strength detected by said received signal strength detection unit to optimum feedback data which decides a gain of said gain control feedback circuit based on preliminary obtained received signal strength and feedback data; and        a feedback data switch unit selecting the optimum feedback data converted by said feedback data conversion unit as an initial value of feedback data of said gain control feedback circuit.     
     
     
       32. A radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising:
   a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal;        a received signal strength detection unit detecting a received signal strength of the signal from the terminal unit, at said radio apparatus;        a feedback data conversion unit carrying out conversion from the received signal strength detected by said received signal strength detection unit to optimum feedback data which decides a gain of said gain control feedback circuit based on an association table of preliminary obtained received signal strength and feedback data; and        a feedback data switch unit selecting the optimum feedback data converted by said feedback data conversion unit as an initial value of feedback data of said gain control feedback circuit.     
     
     
       33. A radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising:
   a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal;        a received signal strength detection unit detecting a received signal strength of the signal from the terminal unit, at said radio apparatus;        a feedback data conversion unit carrying out conversion from the received signal strength detected by said received signal strength detection unit to optimum feedback data which decides a gain of said gain control feedback circuit based on preliminary obtained received signal strength and feedback data; and        a feedback data switch unit selecting the optimum feedback data converted by said feedback data conversion unit as an initial value of feedback data of said gain control feedback circuit.     
     
     
       34. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising the steps of:
   performing automatic gain control on said signal depending on a level of said signal;        detecting a received signal strength of the signal from the mobile terminal unit at an antenna end of said radio apparatus;        carrying out conversion from said detected, received signal strength to optimum feedback data which decides a gain of said automatic gain control based on preliminarily obtained received signal strengths and feedback data; and        selecting said converted optimum feedback data as an initial value of feedback data.     
     
     
       35. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising the steps of:
   performing automatic gain control on said signal depending on a level of said signal;        detecting a received signal strength of the signal from the terminal unit at an antenna end of said radio apparatus;        carrying out conversion from said detected, received signal strength to optimum feedback data which decides a gain of said automatic gain control based on an association table of preliminarily obtained received signal strengths and feedback data; and        selecting said converted optimum feedback data as an initial value of feedback data.     
     
     
       36. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising the steps of:
   performing automatic gain control on said signal depending on a level of said signal;        detecting a received signal strength of the signal from the mobile terminal unit at said radio apparatus;        carrying out conversion from said detected, received signal strength to optimum feedback data which decides a gain of said automatic gain control based on an association table of preliminarily obtained received signal strengths and feedback data; and        selecting said converted optimum feedback data as an initial value of feedback data.     
     
     
       37. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising the steps of:
   performing automatic gain control on said signal depending on a level of said signal;        detecting a received signal strength of the signal from the terminal unit at an antenna end of said radio apparatus;        carrying out conversion from said detected, received signal strength to optimum feedback data which decides a gain of said automatic gain control based on preliminarily obtained received signal strengths and feedback data; and        selecting said converted optimum feedback data as an initial value of feedback data.     
     
     
       38. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a mobile terminal unit, comprising the steps of:
   performing automatic gain control on said signal depending on a level of said signal;        detecting a received signal strength of the signal from the mobile terminal unit at said radio apparatus;        carrying out conversion from said detected, received signal strength to optimum feedback data which decides a gain of said automatic gain control based on preliminarily obtained received signal strengths and feedback data; and        selecting said converted optimum feedback data as an initial value of feedback data.     
     
     
       39. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising the steps of:
   performing automatic gain control on said signal depending on a level of said signal;        detecting a received signal strength of the signal from the terminal unit at said radio apparatus;        carrying out conversion from said detected, received signal strength to optimum feedback data which decides a gain of said automatic gain control based on an association table of preliminarily obtained received signal strengths and feedback data; and        selecting said converted optimum feedback data as an initial value of feedback data.     
     
     
       40. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising the steps of:
   performing automatic gain control on said signal depending on a level of said signal;        detecting a received signal strength of the signal from the terminal unit at said radio apparatus;        carrying out conversion from said detected, received signal strength to optimum feedback data which decides a gain of said automatic gain control based on preliminarily obtained received signal strengths and feedback data; and        selecting said converted optimum feedback data as an initial value of feedback data.     
     
     
       41. A radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising:
   a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal;        a fading rate estimation unit estimating a fading rate of the terminal unit; and        a step constant determiner determining an optimum step constant which decides a gain of said gain control feedback circuit depending on the fading rate estimated by said fading rate estimation unit, wherein        said gain control feedback circuit includes a feedback data calculator calculating feedback data which defines a gain of said gain control feedback circuit based on said signal level and the optimum step constant as determined by said step constant determiner.     
     
     
       42. The radio apparatus according to  claim 41 , wherein
   said fading rate estimation unit calculates a reception response vector of the signal from the terminal unit and estimates a fading rate from a correlation value of said reception response vectors between frames.     
     
     
       43. A radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising:
   a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal,        said gain control feedback including      a first gain control circuit supplying first feedback data allowing the level of said signal to converge to an ideal value slowly, and        a second gain control circuit supplying second feedback data allowing the level of said signal to converge to an ideal value fast;          a received signal strength detection unit detecting a received signal strength of the signal from the terminal unit at an antenna end of said radio apparatus; and        a feedback data switch unit selecting said first feedback data or said second feedback data depending on a detection result from said received signal strength detection unit.     
     
     
       44. A radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising:
   a gain control feedback circuit performing automatic gain control on said signal depending on a level of said signal,        said gain control feedback circuit including      a first gain control circuit supplying first feedback data allowing the level of said signal to converge to an ideal value slowly, and        a second gain control circuit supplying second feedback data allowing the level of said signal to converge to an ideal value fast;          a new terminal detector detecting whether a signal is received from a new terminal unit; and        a feedback data switch unit selecting said first feedback data or said second feedback data depending on a detection result from said new terminal detector.     
     
     
       45. The radio apparatus according to  claim 44 , wherein
   said new terminal detector includes        a demodulation circuit demodulating a specific signal from a new terminal unit, and        an error determiner determining whether an error exists in the signal demodulated by said demodulation circuit and if no error exists, determining that a signal is received from a new terminal unit.     
     
     
       46. The radio apparatus according to  claim 45 , wherein
   said error determiner determines that a signal is received from a new terminal unit if a unique word error does not exist in the signal demodulated in said demodulation circuit.     
     
     
       47. The radio apparatus according to  claim 45  wherein
   said error determiner determines that a signal is received from a new terminal unit if the number of bit errors in a preamble portion is equal to or smaller than a prescribed threshold in the signal demodulated in said demodulation circuit.     
     
     
       48. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising the steps of:
   performing automatic gain control on said signal depending on a level of said signal;        estimating a fading rate of the terminal unit; and        determining an optimum step constant which decides a gain of said automatic gain control, depending on said estimated fading rate, wherein        said step of carrying out automatic gain control includes the step of calculating feedback data which defines a gain of said automatic gain control, depending on said signal level and said optimum step constant as determined.     
     
     
       49. The gain control method according to  claim 48  wherein
   said step of estimating a fading rate includes the step of calculating a reception response vector of the signal from the terminal unit and estimating a fading rate from a correlation value of said reception response vectors between frames.     
     
     
       50. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising the steps of:
   performing automatic gain control on said signal depending on a level of said signal,        said step of performing automatic gain control including      a first step of supplying first feedback data allowing the level of said signal to converge to an ideal value slowly, and        a second step of supplying second feedback data allowing the level of said signal to converge to an ideal value fast;          detecting a received signal strength of the signal from the terminal unit, at an antenna end of said radio apparatus; and        selecting said first feedback data or said second feedback data depending on a result of said detection.     
     
     
       51. A gain control method in a radio apparatus carrying out automatic gain control for a signal from a terminal unit, comprising the steps of:
   performing automatic gain control on said signal depending on a level of said signal,        said step of performing automatic gain control including      a first step of supplying first feedback data allowing the level of said signal to converge to an ideal value slowly, and        a second step of supplying second feedback data allowing the level of said signal to converge to an ideal value fast;          detecting whether a signal is received from a new terminal unit; and        selecting said first feedback data or said second feedback data depending on a result of said detection.     
     
     
       52. The gain control method according to  claim 51  wherein
   said step of detecting a new terminal unit includes the steps of        demodulating a specific signal from a new terminal unit, and        determining whether an error exists in the demodulated signal and if no error exists, determining that a signal is received from a new terminal unit.     
     
     
       53. The gain control method according to  claim 51 , wherein
   said step of determining whether an error exists includes the step of determining that a signal has been received from a new terminal unit when a unique word error does not exist in said demodulated signal.     
     
     
       54. The gain control method according to  claim 51 , wherein
   said step of determining whether an error exists includes the step of determining that a signal has been received from a new terminal unit if the number of bit errors in a preamble portion is equal to or smaller than a prescribed threshold in said demodulated signal.