Correction method for a metric measurement of the quality of transmission in a communication system and device implementing the method
The invention proposes a study of how the inaccurate knowledge of the propagation conditions and interferences and noise, affecting the received signal of a radio transmission, affects the reception and a measurement model used to estimate the quality of the transmission, in a digital radio signal receiver. Actual means to correct the measurement model and improve the accuracy of the estimation of the error rate, or any other indicator of the quality of the transmission, are proposed along with a device comprising such means.
1. A method, implemented on a communication system including an emitter and a receiver, to evaluate an indicator of a quality of data transmission from the emitter to the receiver through a communication channel, from an estimation of an error rate, comprising:
estimating a set of values ({S n }) relative to propagation conditions and interference and noise affecting the communication channel during actual data transmission;
estimating an error rate (FER e ) affecting the data transmission from this set of values according to a given quality model;
correcting, in the quality model, errors made in the estimation of the set of values ({S n }) relative to the propagation conditions and the interference and noise affecting the communication channel by determining an adjustment parameter calculated from a simulation in which a difference between an estimated error rate and a true error rate are determined, and incorporating the adjustment parameter into the quality model for estimation of the error rate (FER e ).
2. The method according to claim 1 , wherein the correcting further includes applying to at least some of the values a correction function.
3. The method according to claim 2 where the correction function of a value, called X, giving the cumulative distribution function of said value based on an exact estimation of said set of values ({S n }) relative to the propagation conditions and the interference and noise affecting the communication channel, called F, giving the cumulative distribution function of said value based on an error prone estimation of said set of values relative to the propagation conditions and the interference and noise affecting the communication channel, called {circumflex over (F)}, consists of applying to the measured value X the correction function F −1 ({circumflex over (F)}(X)) to get a corrected value of X.
4. The method according to claim 3 where said correction function is applied to each of the values of said set of values ({S n }) relative to the propagation conditions and the interference and noise affecting the communication channel.
5. The method according to claim 3 where said correction function is applied to an effective measured value (S eff ) obtained by applying a compression function (f c ) to said set of values ({S n }) relative to the propagation conditions and the interference and noise affecting the communication channel.
6. The method according to claim 3 where said correction function is applied to the result of the estimated error rate (FER e ).
7. The method according to claim 3 where said correction function is applied to an indicator of the quality of the transmission computed from the estimated error rate.
8. A communication system comprising:
an emitter that transmits data through a communication channel to a receiver;
said receiver that receives the transmitted data;
an evaluation unit that evaluates an indicator of the quality of the transmission including:
a first estimation unit that estimates a set of values ({S n }) relative to propagation conditions and interference and noise affecting the communication channel during actual data transmission;
a second estimation unit that estimates an error rate (FER e ) affecting the data transmission from this set of values according to a given quality model; and
a correction unit that corrects errors made in the estimation of the set of values ({S n }) relative to the propagation conditions and the interference and noise affecting the communication channel by determining an adjustment parameter calculated from a simulation in which a difference between an estimated error rate and a true error rate are determined, and incorporating the adjustment parameter into the quality model for estimation of the error rate (FER e ).
9. A device in a communication system which includes an emitter and a receiver, the device comprising:
an evaluation unit that evaluates an indicator of a quality of a transmission from the emitter to the receiver, the evaluation unit including:
a first estimation unit that estimates a set of values ({S n }) relative to propagation conditions and interference and noise affecting the communication channel during actual data transmission;
a second estimation unit that estimates an error rate (FER e ) affecting the data transmission from this set of values according to a given quality model; and
a correction that corrects errors made in the estimation of the set of values ({S n }) relative to the propagation conditions and the interference and noise affecting the communication channel by determining an adjustment parameter calculated from a simulation in which a difference between an estimated error rate and a true error rate are determined, and incorporating the adjustment parameter into the quality model for estimation of the error rate (FER e ).