JP3274781B2 - Time diversity receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is applied to a receiver. The present invention is suitable for use in a mobile communication system. In particular, it relates to a technique for improving received signal quality.

[0002]

2. Description of the Related Art A transmission signal of the same code repeatedly transmitted is repeatedly received and stored, and a reception signal which is estimated to be closest to the transmission signal is selected and output from among the transmission signals to improve reception signal quality. Time diversity receivers are widely known. This conventional example will be described with reference to FIG. FIG. 7 is a block diagram of a conventional time diversity receiver. The operation on the transmitting side is to transmit the same code a plurality of times. Here, a case where quaternary data is received will be described as an example.

[0003] A signal received by an antenna 1 is input to a reception / demodulator 2 and a reception level detector 3. Receive /
The sign of the detector output from the demodulator 2 is judged by the sign judging unit 4 as quaternary data (10, 11, 01, 00).

An example of the above-mentioned code determination will be described with reference to FIG. FIG. 8 is a diagram showing an example of a conventional code determination. There are four reference signal points S ₁ , S ₂ , S ₃ , S _{4 and} are arranged as shown in FIG. Also, the reference signal point S ₁ is made to correspond to the quaternary data “10”, the reference signal point S ₂ is made to correspond to “11”, the reference signal point S ₃ is made to correspond to “01”, and the reference signal point S ₄ is made to correspond to “01”. Corresponds to “01”. Next, in the sign determination, three threshold values (K ₁ > K ₂ > K ₃ ) are used, and FIG.
Determining a detection output by the code determination of the determination timing is predetermined as shown in (a time interval of the code judgment T), "1 When this determination value is K ₁ or more
"Determines that, when it is and K ₂ or more is less than K ₁ is" 0 "determines that, when it is and K ₃ or less than K ₂ is" 11 determines that 01 ", less than K ₃ Sometimes, "0
0 "determines that. Therefore, the detector output determination value at time t ₀ is because it is K _1" or more is determined to be 10 "
Thereafter, at time t ₀ + T, “11”, and at t ₀ + 2T, “1”.
1 ”and t ₀ + 3T are determined to be“ 00 ”.

Subsequently, after the sign determination, the determined quaternary data is input to the signal processing unit 6. The reception level output from the reception level detector 3 is input to the signal processing unit 6 after being determined by the A / D converter 5. The signal processing unit 6 compares the reception level judgment value received this time with the reception level judgment value of the signal received up to the previous time stored in the memory 7 for each same code, and responds to the larger one of the judgment values. A time diversity reception process for selecting quaternary data to be performed is performed. Further, after the time diversity receiving process is completed, the signal processing unit 6 causes the output terminal 8 to output quaternary data. By repeating this operation, high-quality signal transmission can be realized on a fading mobile communication transmission path. The determination value output to the output terminal 8 and the quaternary data corresponding to the determination value may be stored in the memory 7.

[0006]

However, in such a conventional time diversity receiving process, the reception level detector 3 is indispensable for realizing high quality signal transmission, so that the circuit configuration becomes complicated. At the same time, the power consumption of the receiver increases.

[0007] Therefore, it is not suitable for application to a mobile communication terminal in which simplification or downsizing of the circuit configuration and accompanying reduction in power consumption are required.

The present invention has been made in view of such a background, and it is an object of the present invention to provide a time diversity receiver capable of performing time diversity reception processing using a simple circuit configuration and reducing power consumption. Aim.

[0009]

According to the present invention, there is provided a receiving section for receiving a radio signal repeatedly transmitted according to a set time diversity rule, and an A / D for converting a demodulated output of the receiving section into a digital signal. A converter, a memory,
A signal for converting output data of the A / D converter into output data including a plurality of symbol codes and storing the converted data in the memory, and selecting one of the plurality of output data stored in the memory according to the repeated transmission. A time diversity receiver comprising a processing unit.

Here, it is a feature of the present invention that the signal processing section includes a reference signal having a minimum difference (ΔX) between the digital signal and an n-value reference signal point level set at a determination timing. Means for determining the point level as the symbol code thereof, and means for storing the difference (ΔX) together in the memory and selecting a symbol code having the minimum difference (ΔX) from a plurality of output data. It is in the prepared place.

It is desirable that the minimum difference (ΔX) is determined for each code.

[0012]

When receiving a repeatedly transmitted transmission signal of the same code and converting the received radio signal into a digital signal, the level of the signal point and the reference signal point level of the n-value serving as a predetermined criterion are set. Compare with The comparison is performed by taking the difference between the signal point level and the n-value reference signal point level. A symbol code corresponding to the reference signal point level at which the difference becomes minimum is set as digital output data of the received wireless signal. At this time, this difference information is also stored.

When the output data corresponding to the same position is selected from among the receptions performed a plurality of times, the data with the smallest difference is selected and output by referring to the above-mentioned difference information.

Thus, even if fading or other deterioration of the radio channel occurs, a signal which is estimated to be closest to the transmission signal is output. The procedure described above is preferably performed for each code.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.

According to the present invention, a receiving / demodulating device 2 as a receiving portion for receiving a radio signal repeatedly transmitted in accordance with a set time diversity rule, and converting a demodulated output of the receiving / demodulating device 2 into a digital signal. A / D converter 5, a memory 7, and a memory 7 which converts output data of the A / D converter 5 into output data comprising a plurality of symbol codes.
And a signal processing unit 9 for selecting one of the plurality of output data stored in the memory 7 according to the repeated transmission.

Here, a feature of the present invention is that the signal processing unit 9 determines whether the digital signal has a difference (ΔΔ) from an n-value reference signal point level set at the determination timing.
Means for determining the reference signal point level at which X) is the smallest as the symbol code thereof, and the difference (ΔX) is stored in the memory 7 together, and the difference (ΔX) is the smallest among a plurality of output data. Means for selecting a symbol code. That the difference (ΔX) is minimum is determined for each code. The determination result is output to the output terminal 8 as output data.

Next, the operation of the embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a diagram illustrating an example of determining binary data. FIG. 3 is a diagram for explaining the operation of the signal processing unit 9 for binary data. FIG. 4 is a diagram illustrating an example of determination of quaternary data. FIG. 5 is a diagram for explaining the operation of the signal processing unit 9 for quaternary data. FIG. 6 is a flowchart illustrating the operation of the signal processing unit 9. First, a case where binary data is received will be described.

The A / D converter 5 converts the demodulated output of the reception / demodulator 2 into a digital signal. More specifically,
The A / D converter 5 samples the demodulated output of the reception / demodulator 2 and outputs a signal point level q indicated by the demodulated output signal as a sampled value.

As shown in FIG. 2, the signal processing unit 9 determines the signal point level q of the signal received this time for each code and the signal point level between a predetermined reference signal point level (S ₁ , S ₂ ). Are calculated as | S ₁ −q |, | S ₂ −q | (1). Subsequently, the minimum difference ΔX that satisfies ΔX = min _{i = 1,2} (| S _i −q |) (2) is calculated, and the reference signal point level S _X (S ₁ , S ₂ of the reference signal point level) corresponding to the difference ΔX is calculated. One of them). That is, the reference signal point level S _X is the signal point level closest to the signal point level q. In FIG. 2, the signal point level q at time t _0, the difference between the respective reference signal points level S _1, S ₂ between _{the, | S 1 -q | <|} S 2 -q | become. Therefore, | S ₁ -q | is the minimum difference ΔX among these differences, and the reference signal point level S ₁ is selected as the signal point level S _X closest to the signal point level q. At this time, the symbol code corresponding to the reference signal point level S ₁ is “1”, and the signal processing unit 9 stores “1” in the memory 7 as digital output data received for the first time. At this time, information of the difference ΔX (= | S ₁ −q |) is also stored in the memory 7.

Here, assuming that the second reception is performed according to the same procedure, the signal processing unit 9 outputs the first received digital output data “1” stored in the memory 7 and the difference ΔX From the digital output data received for the second time, for example, “0” and the difference ΔY, a difference ΔZ satisfying ΔZ = min (ΔX, ΔY) (3) is calculated, and the corresponding binary data is selected. Perform time diversity reception processing. This binary data is output to the output terminal 8. In this case, if ΔZ = ΔX, the output data is “1”, and if ΔZ = ΔY, the output data is “0”.

Here, the operation in the case of binary data will be described more specifically with reference to FIG. FIG. 3A shows the waveform of the detector output from the receiver / demodulator 2 based on the first received signal. The A / D converter 5 determines the output waveform of the detector at predetermined determination timings (t ₀ , t ₀ + T). In FIG. 3A, the difference ΔX ₁ and the reference signal point level S ₁ at time t ₀ .
Becomes Therefore, the difference ΔX ₁ and the output data “1” are stored in the memory 7. Similarly, the time point t ₀ + T
Then, the difference ΔX ₂ and the reference signal point level S ₂ are obtained. Therefore, difference ΔX ₂ and output data “0” are stored in memory 7.

Subsequently, when the second reception is performed, FIG.
As shown in (b), the difference ΔY ₁ and the reference signal point level S ₁ are obtained at the time point t ₀ + α (α is a retransmission cycle of the same code signal). Therefore, difference ΔY ₁ and output data “1” are stored in memory 7. Similarly, at time t
_{At 0} + α + T, the difference ΔY ₂ and the reference signal point level S ₂
Becomes Therefore, the difference ΔY ₂ and the output data “0” are stored in the memory 7.

The signal processing section 9 compares the first and second reception results stored in the memory 7 to determine ΔX ₁ <
Since it is ΔY ₁ , the output data corresponding to the minimum difference ΔX ₁ after receiving the time diversity becomes “1”, and the binary data “1” is output to the output terminal 8. Also, ΔX ₂ > Δ
Y ₂ , the minimum difference Δ after receiving the time diversity
The output data corresponding to Y ₂ is “0”, and the output terminal 8
, Binary data “0” is output. By repeating this operation, high-quality signal transmission can be realized on a fading mobile communication transmission path.

Next, the case of quaternary data will be described. The A / D converter 5 converts the demodulated output of the reception / demodulator 2 into a digital signal. More specifically, the A / D converter 5 samples the demodulated output of the reception / demodulator 2 and outputs a signal point level q indicated by the demodulated output signal as a sampled value.

As shown in FIG. 4, the signal processing section 9 performs, for each code, a signal point level q of the signal received this time and predetermined reference signal point levels (S ₁ , S ₂ , S ₃ , S ₄ ).
Are calculated as | S ₁ −q |, | S ₂ −q |, | S ₃ −q |, | S ₄ −q | (1). Subsequently, the minimum difference ΔX that satisfies ΔX = min _{i = 1,2,3,4} (| S _i −q |) (2) is calculated, and the reference signal point level S _X (S ₁ , S ₂ , S ₃ , S ₄ ). That is, the reference signal point level S _X is the signal point level closest to the signal point level q. here,
In FIG. 4, the difference between the signal point level q at the time point t ₀ and each of the reference signal point levels S ₁ , S ₂ , S ₃ , and S ₄ is | S ₁ -q | <| S ₂ -q | <| S ₃ -q | <| S ₄ −
q |. Therefore, | S ₁ -q | becomes the minimum difference ΔX among these differences, and the reference signal point level S ₁ is selected as the reference signal point level S _X closest to the signal point level q. At this time, the symbol code corresponding to the reference signal point level S ₁ is “10”, and the signal processing unit 9 stores “10” as the first digital output data in the memory 7.
To be stored. At this time, the difference ΔX (= | S ₁ −q
The information of |) is also stored in the memory 7.

Here, assuming that the second reception is performed according to the same procedure, the signal processing unit 9 outputs the first received digital output data “10” stored in the memory 7 and the difference ΔX From the digital output data received for the second time, for example, “11” and the difference ΔY, a difference ΔZ that satisfies ΔZ = min (ΔX, ΔY) (3) is calculated, and the corresponding four-value data is selected. Perform time diversity reception processing. The quaternary data is output to the output terminal 8. In this case, if ΔZ = ΔX, the output data is “10”, and if ΔZ = ΔY, the output data is “11”.

The operation in the case of quaternary data will be described more specifically with reference to FIG. FIG. 5A shows the waveform of the detector output from the receiver / demodulator 2 based on the first received signal. The A / D converter 5 determines the detector output waveform at predetermined determination timings (t ₀ , t ₀ + T, t ₀ + 2T). FIG.
In (a), the difference ΔX ₁ and the reference signal point level S ₁ at time t ₀ . Therefore, the difference Δ
X ₁ and the output data "10" is stored. Similarly, the difference ΔX ₂ and the reference signal point level S ₂ are obtained at the time point t ₀ + T. Therefore, difference ΔX ₂ and output data “11” are stored in memory 7. At time t ₀ + 2T, the difference becomes ΔX ₃ and the reference signal point level S ₂ . Therefore, the difference ΔX ₃ and the output data “1” are stored in the memory 7.
1 "is stored.

Subsequently, when the second reception is performed, FIG.
As shown in (b), the difference ΔY ₁ and the reference signal point level S ₁ are obtained at the time point t ₀ + α (α is a retransmission cycle of the same code signal). Therefore, difference ΔY ₁ and output data “10” are stored in memory 7. Similarly, at time t ₀ + α + T, the difference ΔY ₂ and the reference signal point level S
It becomes ₃ . Therefore, the difference ΔY ₂ and the output data “01” are stored in the memory 7. At time t ₀ + α + 2T, the difference becomes ΔY ₃ and the reference signal point level S ₂ . Therefore, the difference ΔY ₃ and the output data “1” are stored in the memory 7.
1 "is stored.

The signal processing section 9 compares the first and second reception results stored in the memory 7 to determine ΔY ₁ <
Since it is ΔX ₁ , the output data corresponding to the minimum difference ΔY ₁ after receiving the time diversity is “10”, and the quaternary data “10” is output to the output terminal 8. Also, ΔY ₂
Since <ΔX ₂ , the data corresponding to the minimum difference ΔY ₂ after receiving the time diversity is “01”, and the quaternary data “01” is output to the output terminal 8. Furthermore, ΔX ₃
Since <ΔY ₃ , the data corresponding to the minimum difference ΔX ₃ after receiving the time diversity is “11”, and the quaternary data “11” is output to the output terminal 8. By repeating this operation, high-quality signal transmission can be realized on a fading mobile communication transmission path.

FIG. 6 is a flowchart showing the operation of the signal processing unit 9 described above. Here, description will be made assuming that two receptions are performed. The signal point level q, which is the demodulated output converted to a digital signal in the first reception, is A / D
Input from the converter 5 (S11). The output data and the difference ΔX are written into the memory 7 for each code (S1
2). A signal point level q, which is a demodulated output converted into a digital signal in the second reception, is input from the A / D converter 5 (S13). The output data and the difference ΔY are written into the memory 7 for each code (S14). The difference ΔX and the difference ΔY are compared for each code (S15). as a result,
If the difference ΔX is smaller, the first output data is selected (S16). If the difference ΔY is smaller, the second output data is selected (S17). By these operations, the final data is output from the output terminal 8 (S18).

In the embodiment of the present invention, two receptions have been described for the sake of simplicity. However, the same description can be applied to the case where n receptions are performed.

The data output from the output terminal 8 may be stored in the memory 7 together.

[0034]

As described above, according to the present invention,
Time diversity reception processing can be performed using a simple circuit configuration to reduce power consumption.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of determination of binary data.

FIG. 3 is a diagram for explaining the operation of a signal processing unit for binary data.

FIG. 4 is a diagram showing an example of determining four-value data.

FIG. 5 is a diagram for explaining the operation of a signal processing unit for quaternary data.

FIG. 6 is a flowchart showing the operation of the signal processing unit.

FIG. 7 is a block diagram of a conventional time diversity receiver.

FIG. 8 is a diagram illustrating an example of a conventional code determination.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 antenna 2 reception / demodulator 3 reception level detector 4 code decision unit 5 A / D converter 6, 9 signal processing unit 7 memory 8 output terminal S _{1 to} S ₄ reference signal point level q signal point level ΔX _{1 to} ΔX ₃ , ΔY _{1 to} ΔY ₃ , ΔZ difference

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 1/02-1/04 H04B ⁷ /02-7/12

Claims (2)

(57) [Claims] 1. A receiving section for receiving a radio signal repeatedly transmitted according to a set time diversity rule, an A / D converter for converting a demodulated output of the receiving section into a digital signal, a memory, Signal processing for converting output data of an A / D converter into output data composed of a plurality of symbol codes and storing the converted data in the memory, and selecting one of the plurality of output data stored in the memory according to the repeated transmission. A time diversity receiver comprising: a reference signal point level at which a difference (ΔX) between the digital signal and an n-value reference signal point level set at a determination timing is minimized. Means for determining the symbol code and the difference (ΔX) are stored together in the memory, and Time diversity receiver characterized in that the difference ([Delta] X) is provided with means for selecting a symbol code is minimal. 2. The time diversity receiver according to claim 1, wherein the minimum difference (ΔX) is determined for each code.