JPH0746284A - Fading compensation device - Google Patents

Abstract

PURPOSE:To attain estimate of fading at high accuracy by estimating fading fluctuation through the use of not only fading fluctuation in a pilot symbol but also fading fluctuation in an information symbol. CONSTITUTION:A pilot symbol detection part 6 detects a pilot symbol from a reception signal converted into a base band at an orthogonal demodulation part 3 and sampled by an A/D converter 4. A fading estimate part 7 estimates fading fluctuation in an information symbol based on a pilot symbol detected by the pilot symbol detection part 6 and a re-modulation result obtained from the discrimination result at a re-modulation part 10. The fading fluctuation in the information symbol is compensated by using an estimate value 24 of the fading fluctuation in the information symbol obtained by the estimate part 7 and multiplying its inverse characteristic with a reception signal to obtain a complex base band signal 25 in which the fading fluctuation is compensated. Then the complex base signal is regenerated from the signal discriminated by a discrimination part 9 in the rem-modulation part 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a fading fluctuation compensator for land mobile communications.

[0002]

2. Description of the Related Art In recent years, land mobile communication has made great progress with the diversification of social and economic activities, the widening of the area, and the increasing role of automobiles. Along with this development, digital modulation schemes are being introduced in land mobile communications. When digitizing this land mobile communication, a technology for overcoming fading fluctuations peculiar to land mobile communication is required.
As a fading countermeasure technology, there is a fading fluctuation compensator shown below. 5 and 6 show the configuration of a 16QAM modulator / demodulator having a fading fluctuation compensator using pilot symbols, which is shown in Communication Research Institute Quarterly Vol. 37, No. 1, February 1991. On the transmitter side in FIG. 6, 11 is a baseband signal generation unit, 12 is a pilot symbol insertion unit, 13 is a D / A conversion unit, 14 is a low-pass filter, and 15 is a quadrature modulation unit. Further, on the receiver side in FIG. 5, 1 is a band pass filter and 2 is an AG.
C, 3 are quadrature demodulation units, and 4 is an A / D conversion unit.
The received complex baseband signal 21 converted into a digital signal by the / D converter is input to the pilot symbol detector 6, the fading compensator 8, and the fading estimator 18. Further, the fading estimation unit 18 outputs an estimated value 22 of the fading in the pilot symbol, which is input to the fading compensation unit 8. The fading fluctuation compensated complex baseband signal 23, which is the output of the fading compensation unit 8, is input to the reception signal determination unit 9. Reference numeral 5 is a symbol clock reproducing unit.

Next, the operation will be described. In the transmitter, the baseband signal generator 11 generates a 16QAM-modulated complex baseband signal from a transmission information sequence (digital data). The pilot symbol insertion unit 12 inserts a pilot symbol having a known amplitude and phase for measuring one-symbol fading fluctuation for every N symbols of the complex baseband signal (information symbol) generated by the baseband signal generation unit 11. FIG. 7 shows an example of the insertion interval of pilot symbols at this time. Here, 20 is a pilot symbol and 19 is an information symbol. In FIG. 7, the frame length (the number of symbols from the pilot symbol to the next pilot symbol) N is 4. When the symbol timing period is T _S , the pilot symbol timing period T _p is given by the following equation. T _p = NT _S (1) From this, the timing t _{k, m} of the m th symbol in the k th frame is represented by t _{k, m} = {k + (m / N)} T _p (2) . However, k = 1, 2, ..., M = 1, 2,
... N. Here, if the first symbol of the kth frame is the timing of the pilot symbol,
This timing can be represented by t = t _{k, 1} . Hereinafter, for ease of explanation, the first symbol (m = 1) of each frame is assumed to be a pilot symbol. The complex baseband signal with the pilot symbol inserted is converted into an analog signal by the D / A conversion unit 13, band-limited by the low-pass filter 14, and then modulated by the quadrature modulation unit 15 and transmitted. In this conventional example, the modulation system is a modulation system in which the in-phase component and the quadrature component of the carrier wave carry information.
6QAM is used. The transmission signal x (t) at this time is described as follows. x (t) = {a _I (t) + ja _Q (t)} exp [jωt] (3) where j is an imaginary unit, a _I (t): in-phase component of the transmitted complex baseband signal a _Q (T): Quadrature component of transmitted complex baseband signal ω: Transmission angular frequency

At the receiving side, an envelope peculiar to land mobile communication and a signal that has undergone fading in which the phase changes abruptly are received. The received signal y (t) at this time has a form in which x (t) is multiplied by fading fluctuation as shown by the following equation. y (t) = x (t) r (t) exp [jθ (t)] where r (t): amplitude fluctuation due to fading θ (t): phase fluctuation due to fading. First, the bandpass filter 1 removes out-of-band noise of the received signal, and the AGC 2 secures the dynamic range in the A / D converter 4. The symbol clock regenerator 5 regenerates the symbol clock using this signal,
The signal is supplied to the fading estimation unit 18 and the fading compensation unit 8. Further, the quadrature demodulation unit 3 demodulates the received signal and converts it into a complex baseband signal. Further, the signal converted into the complex base band by the orthogonal demodulation unit 3 is converted into a digital signal by the A / D conversion unit 4. The received complex baseband signal 21 at this time is expressed by the following equation. Note that u _I (t), u
_Q (t) is the in-phase and quadrature components of the received complex baseband signal. u (t) = u _I (t) + ju _Q (t) = c (t) {a _I (t) + ja _Q (t)} (5) where c (t) = r (t) exp [jθ (T)] = c _I (t) + jc _Q (t) (6) is a complex envelope of fading fluctuation, and c _I (t),
c _Q (t) indicates the in-phase component and the quadrature component of the fading fluctuation, respectively.

The pilot symbol detector 6 detects from this complex baseband signal a pilot symbol having a known amplitude and phase which is periodically inserted by the pilot symbol inserter on the transmitting side. Since the detected pilot symbol u _P (t) has a pilot symbol timing t = t _{k, 1} , u _P (t _{k, 1} ) = r (t _{k, 1} ) exp [jθ (t _{k, 1} ). ] {A _PI (t _{k, 1} ) + ja _PQ (t _{k, 1} )} = c (t _{k, 1} ) {a _PI (t _{k, 1} ) + ja _PQ (t _{k, 1} )} (7) Shown. Note that a _PI (t _{k, 1} ) and a _PQ (t _{k, 1} ) represent the in-phase component and the quadrature component of the complex baseband signal of the pilot symbol, where the amplitude and phase values of the pilot symbol are known. , A _PI (t
_The fading fluctuation amount c (t _{k, 1} ) can be obtained by using the values of _{k, 1} ) and a _PQ (t _{k, 1} ).

The fading estimation unit 18 measures the amount of fading variation in each pilot symbol from the pilot symbols detected by the pilot symbol detection unit 6. The measurement result c _M (t) is c _M (t _{k, 1} ) = u _P (t _{k, 1} ) / {a _PI (t _{k, 1} ) + ja _PQ (t _{k, 1} )} = r _M ( t _{k, 1} ) exp [jθM (t _{k, 1} )] = c _MI (t _{k, 1} ) + jc _MQ (t _{k, 1} ) (8). When the influence of noise is ignored, the measured fading variation c _M (t _{k, 1} ) becomes equal to the actual fading variation c (t _{k, 1} ). Next, using this value, the estimated value 22 of the fading fluctuation in the information symbol is obtained.

Details of the fading estimation method in the fading estimation unit 18 will be described. Since the pilot symbol insertion interval is as shown in FIG. 7, the fading fluctuation measurement values c _MI (t _{k, 1} ) and c _MQ (t _{k, 1} )
Corresponds to sampling the fading fluctuation at the pilot symbol insertion interval T _P. However, k = 1
2, 3, ... Therefore, if the frequency component included in the fading fluctuation is ½ T _P or less, the sample values c _MI (t _{k, 1} ) and c _MQ (t _{k, 1} ) are converted to the ideal low-pass filter according to the sampling theorem. The fading fluctuation is reproduced by passing through, and it becomes possible to estimate the fading fluctuation in the information symbol. However, in this conventional example, in consideration of easiness of deviceization and processing delay, a low order (second order (in the conventional example this time) is used without using an ideal low-pass filter that has a large device scale and a large processing delay. (3 taps) FIR filter, and Gaussian interpolation formula () is used as a coefficient) to implement the apparatus. This is a measurement of fading variation in pilot symbols c _MI (t _{k, 1} ), c _MQ (t _{k, 1} ), and a measurement of fading variation in pilot symbols one frame before c _MI (t _k-1,1). ), C _MQ (t
_k−1,1 ) and the measured values of fading fluctuation in the pilot symbol after one frame c _MI (t _{k + 1,1} ), c _MQ (t
By using _{k + 1,1} ) and performing the filter operation shown in Equation 1, an estimated value r _E (t of the amplitude variation of fading in symbols (information symbols) other than pilot symbols is obtained.
_{k, x} ) and the estimated value θ _E (t _{k, x} ) of the phase fluctuation, or the in-phase component and the quadrature component c _EI (t) of the fading fluctuation.
_{k, x} ) and c _EQ (t _{k, x} ) are estimated. However, x = 2
3, ... N.

[0008]

[Equation 1]

However, Q _{a, b} are tap coefficients of the following fading fluctuation estimation filter.

[0010]

[Equation 2]

The fading compensation unit 8 estimates the fading variation 22 obtained by the fading estimation unit 18.
And the inverse characteristic thereof is multiplied by the complex baseband signal to compensate for fading of the complex baseband signal of the information symbol and obtain the complex baseband signal 23 in which fading fluctuation is compensated. Next, the fading fluctuation compensated signal is judged by the judging section 9 to reproduce digital data from the fading fluctuation compensated complex baseband signal.

[0012]

In the conventional example, in order to reduce the device scale and the processing delay, the order (the number of taps) is not used in the estimation of the fading fluctuation without using the ideal low pass filter.
It uses a low-pass filter with less noise. Considering an actual receiving system, the received signal (information symbol and pilot symbol) is received with Gaussian noise superimposed on fading fluctuation. Here, Gaussian noise is noise with an average of 0. When estimating fading fluctuations from pilot symbols that are subject to this fading fluctuation and have noise superimposed, if a sufficiently high-order filter (with many taps) such as an ideal low-pass filter is used, the effect of noise superimposed on the pilot symbols Are averaged and do not affect fading estimation (fading variation can be estimated with sufficient accuracy). However, when a filter with a low order (a small number of taps) is used as in the conventional example, the noise superimposed on the pilot symbols is not sufficiently averaged, so that there is a drawback that the estimation accuracy deteriorates. Also, in order to sufficiently average the effects of noise superimposed on the pilot symbols, it is necessary to average the noise for a long time by using a filter with a high order (a large number of taps), which results in a large processing delay. there were.

The present invention has been made to solve the above problems, and it is an object of the present invention to improve the estimation accuracy of fading estimation without increasing the device scale and the processing delay.

[0014]

In order to achieve the above object, in a fading compensation apparatus according to claim 1 of the present invention, a fading fluctuation compensating apparatus using pilot symbols is used, and fading in information symbols is performed using a determination result. A means for measuring the fluctuation is provided, and the fading fluctuation is estimated using the fading fluctuation in the pilot symbol and the fading fluctuation in the information symbol measured from the information symbol using the determination result. The fading compensation apparatus according to claim 2 of the present invention is the fading estimation apparatus according to claim 1, wherein an error correction coding section is provided on the transmitter side, and an error occurs between the decision section on the receiver side and the fading fluctuation estimation section. A correction unit is provided.

[0015]

In the fading fluctuation compensating apparatus according to claim 1 configured as described above, the fading fluctuation is estimated not only by the fading fluctuation in the pilot symbol but also by the fading fluctuation in the information symbol in the fading estimation unit. , The effects of noise superimposed on the received signal are sufficiently averaged, and as a result, fading estimation can be performed with high accuracy, and the accuracy of fading compensation can be improved. Claim 2 constructed as described above
In the fading fluctuation compensating apparatus according to the present invention, an error correction method is added to the invention according to claim 1,
Since the error correction is performed even when the determination error occurs in the invention according to the above aspect, the deterioration of the fading estimation accuracy does not occur, and thus the deterioration of the characteristics when the determination error occurs can be prevented.

[0016]

EXAMPLES Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a block diagram of a receiver using a fading compensation device showing a first embodiment of the present invention.
The transmitting apparatus of the present invention shown in FIG. 2 is the same as that of the conventional example shown in FIG. In the figure, 10 is a re-modulation unit, 7 is a pilot symbol detected by the pilot symbol detection unit, and a fading variation in the pilot symbol is measured,
Further, the re-modulated signal of the information symbol fed back from the re-modulation unit 10 and the received signal of the information symbol sampled by the A / D conversion unit 4 are compared, fading fluctuations in the information symbol are measured, and these pilot symbols and It is a fading fluctuation estimator that estimates the fading fluctuation in the information symbol from the measured value of the fading fluctuation in the information symbol. The output of the fading compensation unit 7 is the estimated value 24 of the fading fluctuation of the information symbol estimated from the measured value of the fading fluctuation in the pilot symbol and the information symbol. This estimated value 24 is input to the fading compensation unit 8. Further, the output 25 of the fading compensation unit 8 is a complex baseband signal in which the fading variation is compensated by using the fading variation estimated value 24 of the information symbol, and is input to the determination unit 9. Note that 1 to 6, 8, 9, and 21 are the same as in the conventional example.

The operation of the fading compensation device having the above configuration will be described. Note that the operations of 1 to 6, 8 and 9 on the transmitter side and the receiver side are the same as in the conventional example, and therefore description thereof is omitted. First, in the pilot symbol detection unit 6, the quadrature demodulation unit 3 converts to baseband A
A pilot symbol is detected from the received signal sampled by the / D converter 4. The fading estimation unit 7 estimates the fading fluctuation in the information symbol based on the pilot symbol detected by the pilot symbol detection unit 6 and the remodulation result obtained from the determination result by the remodulation unit 10 described later. The details of the operation of the fading estimation unit 7 will be described later. By using the estimated value 24 of the fading fluctuation in the information symbol obtained by the fading estimation unit 7 and multiplying the inverse characteristic by the received signal, the fading fluctuation in the information symbol is compensated and the fading fluctuation is compensated. Obtain the complex baseband signal 25. The determination unit 9 determines the signal in which the fading fluctuation is compensated by the fading compensation unit, and reproduces the transmission information sequence (digital data) from the received signal such as 16QAM.

The remodulation unit 10 regenerates a complex baseband signal from the transmission information sequence (digital data) reproduced by the determination unit 9. This operation is the same as that of the baseband signal generator 11 of FIG. Since this complex baseband signal is reproduced from the received data, if there is no determination error in the received data, a signal corresponding to the transmitted complex baseband signal that is not subject to fading fluctuation is reproduced. Therefore, when the fading estimation unit 7 compares the re-modulated complex baseband signal with the received complex baseband signal, the amount of fading fluctuation in the information symbol can be measured.

The fading estimation unit 7 uses the pilot symbols detected by the pilot symbol detection unit 6 as in the conventional fading estimation unit 18, and measures the amount of fading fluctuation in the pilot symbols. Further, the fading estimation unit 7 estimates the fading fluctuation in the information symbol from the remodulation result obtained by the remodulation unit 10 and the received signal as follows.

Complex baseband of the received information symbols
Signal is u (t_{k-1, x} ) And the remodulated complex baseband
Signal d_r (T_{k-1, x} ) Is u (t_{k-1, x} ) = C_i (T_{k-1, x} ) A_i (T_{k-1, x} ) + Jc_q (T_{k-1, x} ) A _q (T_{k-1, x} ) = R (t_{k-1, x} ) Exp [jθ (t_{k-1, x} )] {A_i (T_{k-1, x} ) + Ja_q (T_{k-1, x} )} (9) d_r (T_{k-1, x} ) = A_i (T_{k-1, x} ) + Ja_q (T_{k-1, x} ) (10) However, the first symbol in each frame is
Since it is an ilot symbol, x = 2, 3, 4, ...
Note that n is the frame length, and if there is no error in the determination result,
I assumed that For this reason, the information symbol
Aging fluctuation c_m (T_{k-1, x} ) Is calculated by the following formula. c_m (T_{k-1, x} ) = U (t_{k-1, x} ) / D_r (T_{k-1, x} ) = [R (t_{k-1, x} ) Exp [jθ (t_{k-1, x} )] {A_i (T_{k-1, x} ) + Ja _q (T_{k-1, x} )} / {A_i (T_{k-1, x} ) + Ja_q (T_{k-1, x} )} = R (t_{k-1, x} ) Exp [jθ (t_{k-1, x} )] = C_mi(T_{k-1, x} ) + Jc_mq (T_{k-1, x} ) (11) This measured value c_m (T_{k-1, x} ) And the pilot symbol
Measurement value c_m (T_k-1,1 ), C_m (T_{k, 1} ), C_m 
(T_{k + 1,1} ), The information symbol
Estimate aging fluctuations.

[0021]

[Equation 3]

However, Q _{a, b} are tap coefficients of the fading fluctuation estimation filter.

The fading compensation estimated value 24 is used, and the fading compensation unit 8 multiplies the inverse characteristic of the estimated value 24 to multiply the fading of the complex baseband signal, thereby fading variation compensated complex base. The band signal 25 is obtained.

Conventionally, a 3-tap FIR filter is constructed from measured values of fading fluctuation in pilot symbols at times t _k-1,1 , t _{k, 1} and t _{k + 1,1} at time t _k.
While fading fluctuations of _{k, x} , x = 2, 3, ..., N are estimated, the fading compensation device according to the present invention is configured as described above, so that the time t _{k- 1,1} ,
Not only the three pilot symbols t _{k, 1} and t _{k + 1,1} are used for estimation, but also time t _k-1,2 , t _k-1,3 , ...
Since a fading variation is estimated by constructing a 3+ (N-1) tap FIR filter using fading variation in information symbols of t _{k-1, n} , Gaussian noise superimposed on the received signal (information symbol and pilot symbol) is also used. The effects of are sufficiently averaged, and fading can be estimated with higher accuracy. As a result, it is possible to compensate for fading fluctuation with high accuracy.

Example 2. Embodiment 2 of the present invention will be described below with reference to the drawings. 3 and 4 are block diagrams of a transmitter / receiver using a fading compensator according to a second embodiment of the present invention. In the figure, 17 is an error correction coding unit, and 16 is an error correction unit. Since 1 to 15 are the same as the conventional example and the first embodiment, the description thereof will be omitted.

First, in the transmission apparatus of FIG. 4, the error correction coding unit 17 performs error correction coding on the transmission information sequence. 11 to 15 using this error correction coded data sequence
Then, a transmission signal is generated as in the conventional example and the first embodiment.

Next, in the receiving apparatus of FIG. 3, the error correcting section 16 performs error correction from the digital data obtained by the judging section 9 and reproduces the transmission information sequence. The error correction coding unit 17 again performs the same error correction coding as on the transmitting side using the transmission information sequence that has been error-corrected by the error correction unit 16, and inputs the result to the re-modulation unit 10.

Example 1. In the information symbol
When measuring the aging fluctuation, the
If there is a bit error in the digital data, Equation 11
As shown, there is an error in the measurement of fading variation.
Will end up. However, d (t_{k-1, x} ) Contains a judgment error
It is a remodulated signal. d (t_{k-1, x} ) = D_i (T_{k-1, x} ) + Jd_q (T_{k-1, x} ) (12) Note that d (t_{k-1, x} ) Includes a judgment error, d_i (T
_{k-1, x} ), D_q (T_{k-1, x} ) Is the transmitted complex baseband signal
Issue a_i (T_{k-1, x} ), A_q (T_{k-1, x} ) Different value
To have. c_m (T_{k-1, x} ) = D (t_{k-1, x} ) / D_r (T_{k-1, x} ) = [R (t_{k-1, x} ) Exp [jθ (t_{k-1, x} )] {D_i (T_{k-1, x} ) + Jd _q (T_{k-1, x} )}] / A_i (T_{k-1, x} ) + Ja_q (T_{k-1, x} )} (13) where {d_i (T_{k-1, x} ) + Jd_q (T_{k-1, x} )} / {A_i (T_{k-1, x} ) + Ja_q (T_{k-1, x} )} ≠ 1 (14) Therefore c_m (T_{k-1, x} ) ≠ r (t_{k-1, x} ) Exp [jθ (t_{k-1, x} )] = C_i (T_{k-1, x} ) + Jc_q (T_{k-1, x} ) (15) In this way, there is an error in the measurement result of fading fluctuation.
, The fading measurement value c_m (T_{k-1, x} )
Is different from the fading fluctuation,
The problem that estimation accuracy deteriorates and transmission characteristics deteriorate
There was a subject.

On the other hand, in the second embodiment of the present invention, since the error correction method is added, the probability of the bit error becomes smaller than that of the first conventional example, and the error due to the bit error occurs when measuring the fading fluctuation of the information symbol. The probability of inclusion is small. As a result, the deterioration of the estimation accuracy of the fading fluctuation can be suppressed to be smaller than that of the conventional example 1, so that the deterioration of the transmission characteristics can be prevented.

In the above embodiment, the modulation method is 16QA.
The case where M is used has been described, but as a modulation method,
Even when a modulation method other than 16QAM is used, the same effect as in the above embodiment can be obtained. Further, in the above-described embodiment, even when a signal point having a known arbitrary amplitude and phase is used as the pilot symbol, the same effect as that in the above-described embodiment is obtained. In the above embodiment, the second-order FIR filter is used for fading estimation, but the same effect can be obtained even when a filter having an order other than second-order is used for fading estimation. Further, the same effect can be obtained by using a coefficient other than that shown in this embodiment as the coefficient of this filter. Further, in this embodiment, the FI
Although the R filter is used, the same effect is obtained even when a filter of any other format is used. It is needless to say that the present invention has the same effect when the fading fluctuation of the information symbol is estimated / compensated by using the position or the pilot symbol insertion interval different from that of the above embodiment. Further, in the above embodiment, t _{k, 2} , t _{k, 3} , ...
Although the case where the fading fluctuation at t _{k, N} is compensated has been shown, it goes without saying that the same effect can be obtained in the case where the fading fluctuation at other times is compensated. Further, in the above embodiment, the case where the generation of the complex baseband signal and the like are performed by the digital signal processing on the transmitting side is described, but the same effect is obtained when the complex baseband signal is generated and the like in an analog manner. . Similarly, on the receiving side, analog signal processing is used to detect pilot symbols and estimate fading fluctuations.
The same effect is obtained even when compensation is performed. In addition,
When the signal processing is performed by analog, the A / D and D / A converters in the above embodiment are not used, but it goes without saying that the intended purpose can be achieved in that case as well. In the above embodiment, the band pass filter 1, AGC
It goes without saying that the intended purpose can be achieved even if the low-pass filter 14 is not used or the order thereof is different from that of the above embodiment.

[0031]

Since the invention according to claim 1 is configured as described above, it has the following effects.

Since the fading estimation unit estimates not only the fading variation in the pilot symbol but also the fading variation in the information symbol by using the remodulated signal of the information symbol obtained in the remodulation unit, the fading variation is estimated. Compared to the case of estimating fading fluctuation of information symbol using only fading fluctuation of pilot symbol as in the example, the effect of Gaussian noise superimposed on the received signal (information symbol and pilot symbol) is sufficiently averaged and higher Accurate estimation of fading is possible. As a result, it is possible to compensate for fading fluctuation with high accuracy. Highly accurate fading estimation is possible, and the accuracy of fading compensation can be improved.

Since the invention according to claim 2 is configured as described above, it has the following effects.

By adding the error correction method to the invention according to claim 1, it is possible to prevent the deterioration of the characteristics when the judgment error occurs in the invention according to claim 1.

[Brief description of drawings]

FIG. 1 is a block diagram of a receiver according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a transmission device according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a receiver according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a transmitter according to a second embodiment of the present invention.

FIG. 5 is a block diagram of a receiver of a conventional fading compensation device using pilot symbols.

FIG. 6 is a block diagram of a transmitter of a conventional fading compensation device using pilot symbols.

FIG. 7 is an example of a frame configuration for explaining an insertion interval of pilot symbols.

[Explanation of symbols]

1 band pass filter 2 AGC 3 quadrature demodulation unit 4 A / D conversion unit 5 symbol clock recovery unit 6 pilot symbol detection unit 7 fading estimation unit 8 fading compensation unit 9 determination unit 10 remodulation unit 11 baseband signal generation unit 12 pilot symbols Insertion unit 13 D / A conversion unit 14 Low-pass filter 15 Quadrature modulation unit 16 Error correction unit 17 Error correction coding unit 18 Conventional fading estimation unit 19 Information symbol 20 Pilot symbol 21 Received complex baseband signal 22 Fading in information symbol Estimated value of fluctuation 23 Complex baseband signal compensated for fading fluctuation 24 Estimated value of fading fluctuation of information symbol estimated from measured value of fading fluctuation in pilot symbol and information symbol 25 Fading change Motion-compensated complex baseband signal

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H04B 17/00 C 7406-5K

Claims (2)

[Claims] 1. A baseband signal generation unit for generating a complex baseband signal (hereinafter referred to as an information symbol) according to transmission data, and a pilot symbol having a predetermined amplitude and phase in the information symbol is periodically set. In a transmitter equipped with a pilot symbol inserting section for inserting the pilot symbol, a pilot symbol detecting section for detecting the pilot symbol periodically inserted in the transmitting apparatus from the received signal of the transmitting apparatus, and the pilot symbol detecting section. A fading estimation unit that measures the fluctuation amount of the detected pilot symbol and estimates the fluctuation amount of the information symbol,
In a fading compensation apparatus including a fading compensation unit that compensates for fading fluctuations of the information symbols using the fluctuation amount estimated by the fading estimation unit, fading fluctuations detected from the fading-compensated information symbols and fading fluctuations of the pilot symbols. A fading compensation apparatus having means for estimating and compensating for fading fluctuations of information symbols in accordance with the amount. 2. An error correction coding unit for error correction coding an information symbol on the transmission side, and an error correction decoding unit for error correcting the fading-compensated information symbol on the reception side using the error correction code. 2. The fading compensation device according to claim 1, wherein the error-corrected information symbol is used for fading detection of the information symbol.