JPH08116313A - Radio transmission system - Google Patents

Abstract

PURPOSE: To improve data transmission quality while permitting the occurrence of a bit error in a radio transmission system. CONSTITUTION: This system is the radio transmission system equipped with a transmitter 11 which transmits single or plural frames and cells including transmission information by modulating a carrier wave signal by the logic value or combination of a bit stream constituted individually, and a receiver 13 which receives a reception wave arriving from the transmitter 11 by applying an antenna switching diversity system in unit of frame or cell and obtains the bit string by applying demodulation processing. The transmitter 11 includes an arrangement change means 15 which changes the arrangement of a bit for which priority for the evading request of the bit error is set higher or the partial bit stream in the bit stream to the leading position or in the neighborhood of the frame and the cell. The receiver 13 includes a processing means 17 which restores the arrangement changed by the arrangement change means 15 and applies information processing adaptive for the arrangement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless transmission system for serially transmitting transmission information via a wireless transmission line in which fading occurs.

[0002]

2. Description of the Related Art In a radio transmission path formed between a base station and a mobile station of a mobile communication system, a multipath propagation path is formed because reflection, analysis, scattering, etc. occur due to the topography and features around the mobile station. It is formed. Therefore, the received waves coming from the base station to such a mobile station are given as the vector sum of the received waves from various propagation paths, and the geographical distribution of the electric field strength has a random standing wave property. Will be things.

Further, in the mobile station, in order to suppress the bit error of the transmission information received from the base station during the period when the electric field strength of the received wave becomes small due to such fading, reception by a plurality of antennas is performed. A diversity reception method is applied in which waves are combined by an equal-gain combining method (equal-ratio combining method) or a maximum-ratio combining method, and among these received waves, the one having the highest envelope level is sequentially selected.

Further, with respect to mobile stations, cost reduction, downsizing, power consumption reduction, etc. are strongly demanded, and it is not allowed to mount a receiver for each branch. The antenna switching reception method, which connects to the input of the receiver, is applied. In particular, the antenna switching diversity method, in which the one with the highest electric field strength of the received wave is selected from the plurality of antennas and connected to the receiver, is often used because the device configuration is simple and the above requirements are met. It is used in mobile station equipment.

The received wave arriving at the mobile station is accompanied by fading in which the electric field strength (envelope component) and the phase randomly fluctuate as the mobile station moves. Such fading is generally described above. Since the topography and the state of the features are almost constant in a section of several tens of meters along the route of the movement, it can be regarded as a steady state in such a section.

[0006]

However, in a mobile station to which the above-mentioned antenna switching diversity system is applied,
When receiving the transmission information transmitted from the base station in the process of radio channel setting control performed opposite to the base station,
The reception electric field level of each antenna is measured at the time when the beginning of each frame including the transmission information is received, and the antenna having the maximum reception electric field level is fixed and selected during reception of the corresponding frame.

Therefore, of the bits included in such a frame, the lower the electric field level is, the lower the bit arranged in the latter half along the time axis, and the symbol including the bit (transmission adapted to the modulation method in this case). The unit is.)
It is easy for bit errors to occur.

The bit error rate in a frame increases sharply as the fading pitch increases, as shown in FIGS. It should be noted that the curves shown in the same figure show the bit error rates under the condition that the average value of the bit error rates in the frame having the frame length of 6.67 ms is "0.01" for the fading pitches of 80 Hz, 40 Hz, and 10 Hz, respectively. The distribution is shown.

An object of the present invention is to improve the data transmission quality while allowing the occurrence of bit errors.

[0010]

FIG. 1 is a block diagram showing the principle of the invention described in claim 1. In FIG. The invention according to claim 1 is a transmitter 11 which modulates and transmits a carrier signal by a logical value of a bit string or a combination of the logical values of bit strings individually forming a single frame or a plurality of frames or cells containing transmission information. , The received wave arriving from the transmitter 11 via the wireless transmission path is received in units of frames or cells by applying the antenna switching diversity method, and is subjected to demodulation processing adapted to the modulation method and included in the frame or cell. In a wireless transmission system including a receiver 13 for obtaining a bit string, the transmitter 11
The receiver 13 includes a layout changing means 15 for changing the layout of the bit or partial bit string for which a high bit error is required to be avoided to the head of the frame or cell or its vicinity.
Is characterized by including processing means 17 for restoring the arrangement changed by the arrangement changing means 15 for the bit string obtained by performing the demodulation processing, or for performing information processing adapted to the arrangement.

FIG. 2 is a block diagram showing the principle of the invention described in claim 2. According to a second aspect of the present invention, a frame or a cell is generated by individually performing error correction coding on a single or a plurality of pieces of transmission information and arranging them in series, and a logical value of a bit string constituting the frame or the cell or its A transmitter 21 that modulates and transmits a carrier signal by a combination of logical values, and a received wave that arrives from the transmitter 21 via a wireless transmission path are received by applying an antenna switching diversity method in frame or cell units and modulated. In the wireless transmission system including the receiver 23 that obtains single or plural transmission information by performing the demodulation process adapted to the system of 1) and the decoding process adapted to the system of error correction coding, As a method, the error correction in which the number of correctable bits is larger when the position where the codeword is to be arranged is farther from the beginning of the frame or cell Wherein the coding scheme is applied.

FIG. 3 is a block diagram showing the principle of the invention described in claim 3. According to a third aspect of the present invention, in the wireless transmission system according to the second aspect, the transmitter 21 is a receiver 2
Fading period detection means 31 for obtaining the average period of fading associated with the received wave by capturing the electric field strength of the received wave arriving from the wireless station where 3 is arranged via the wireless transmission path in time series order, and analyzing the frequency. The average period obtained by the fading period detecting means 31 is monitored, and the position where the bit error rate on the frame or cell can be regarded as a predetermined threshold value is obtained based on the average period and the fading amplitude distribution. Coding range changing means 33 for setting the boundary of the application range of each error correction coding method at that position, and the combination of the methods is variably set according to the boundary set by the coding range changing means 33, and the combination thereof is set. And a coding method changing means 35 for adding identification information indicating the Characterized by comprising a decoding method adapting means 37 for variably setting the combination of the error correction coding scheme to be applied to decoding processing based on the obtained identification information by the processing.

FIG. 4 is a block diagram of the principle of the invention as defined in claim 4. According to a fourth aspect of the present invention, a transmitter 41 that adds a training pattern to the beginning of a bit string indicating transmission information, modulates a carrier signal with a logical value of the training pattern and the bit string, or a combination of the logical values and transmits the modulated carrier signal. And a received wave arriving from the transmitter 41 via the wireless transmission path is received, demodulation processing adapted to the modulation method is performed, and the transmission characteristic of the wireless transmission path is determined based on the distortion of the pulse indicating the training pattern. In the wireless transmission system that includes a receiver 43 that obtains transmission information under the equalization, the transmitter 41 is arranged with a bit or a partial bit string that is highly required to avoid bit errors. To the head of the bit string or to the vicinity thereof, and the receiver 43
Is characterized by including a processing means 47 for restoring the arrangement changed by the arrangement changing means 45 for the bit string obtained by performing the demodulation processing, or for performing information processing adapted to the arrangement.

[0014]

In the radio transmission system according to the first aspect of the present invention, the receiver 13 receives the received wave accompanied by fading by applying the antenna switching diversity system for each frame or cell. Therefore, the electric field strength of the received wave is likely to decrease as the distance from the beginning of the corresponding frame or cell increases along the time axis. However, in the transmitter 11, the arrangement changing unit 15 arranges, of the bits or partial bit strings forming the frame or cell to be transmitted, those having high requirements to avoid the bit error caused by the fading described above. To the beginning of the frame or cell or its vicinity. Further, the transmitter 11 modulates a carrier signal with a logical value of a bit string constituting a frame or cell whose arrangement has been changed in this way or a combination of the logical values, and transmits the modulated carrier signal.

Further, the receiver 13 receives the frame or cell whose arrangement has been changed as described above as a received wave arriving via the wireless transmission path, performs demodulation processing, and processing means 17
Restores the arrangement changed by the arrangement changing means 15 for the bit string obtained by the demodulation processing,
Information processing suitable for the arrangement is performed.

That is, there is no redundancy, the amount of processing that should be activated in response to a bit error is large, or the bit or partial bit string that cannot be completely adapted to the bit error is the frame or cell. Since it is arranged at the head or in the vicinity thereof, the receiving process is stabilized while allowing a bit error due to fading.

In the radio transmission system according to the second aspect of the present invention, the receiver 23 receives the received wave accompanied by fading by applying the antenna switching diversity system for each frame or cell. Therefore, the electric field strength of the received wave is likely to decrease as the distance from the beginning of the corresponding frame or cell increases along the time axis. However, in the transmitter 11, as for the individual transmission information to be error-correction-coded and arranged in the frame or cell to be transmitted, the error that has a larger number of correctable bits as it is farther from the head of the frame or cell. A correction coding method is applied. Furthermore, the transmitter 11
Generates the above-mentioned frame or cell by error-correcting encoding individual transmission information based on such an error-correcting encoding method and arranging them serially, and logical values of bit strings constituting the frame or cell or The carrier signal is modulated by the combination of the logical values and transmitted.

Further, the receiver 23 receives the received wave coming from the transmitter 21 via the wireless transmission line by applying the antenna switching diversity method to each frame or cell, and performs the demodulation process and the error correction described above. Decoding processing adapted to the encoding method is performed to obtain individual transmission information.

That is, since error correction can be performed on a larger number of bits in a field of a frame or a cell in which bit errors are more likely to occur due to fading, data transmission quality can be obtained for transmission information having no redundancy. Therefore, it is possible to greatly reduce the possibility that a process with a large processing amount is activated in response to a bit error, or a process that cannot necessarily complete a countermeasure against a bit error is activated.

In the wireless transmission system according to the invention described in claim 3, in the wireless transmission system according to the invention described in claim 2, the fading cycle detection means 31 is arranged with the receiver 23 via a wireless transmission path. The average period of fading associated with the received wave is obtained by capturing the electric field strength of the received wave arriving from the wireless station in time series and analyzing the frequency. The coding range varying means 33 monitors the average period, and based on the average period and the fading amplitude distribution described above, it can be considered that the bit error rate becomes a predetermined threshold value on each frame or cell. The position is obtained, and the position is set as the boundary of the applicable range of each error correction coding method. Further, the encoding method changing means 3
Reference numeral 5 variably sets a combination of compression encoding methods to be applied to each field based on the boundary, and adds identification information indicating the combination to a frame or a cell.

Further, in the receiver 23, the coding system adaptation means 37 acquires the identification information obtained by demodulating the received wave arriving via the above-mentioned radio transmission path, and the identification information of the identification information is obtained. The combination of error correction coding methods to be applied to the decoding process is variably set based on the contents.

Therefore, the boundary points of the fields constituting the frame or cell and the compression coding method to be applied to the generation of each field are dynamically variably set in accordance with the fading average period, and the receiver 23 is It is possible to perform the reception process adapted to the contents of the setting.

In the wireless transmission system according to the invention described in claim 4, the transmitter 41 adds a training pattern to the beginning of a bit string indicating transmission information, and a predetermined carrier wave is obtained by these logical values or a combination of the logical values. Modulate the signal and transmit. The receiver 43 receives a received wave coming from such a transmitter 41 via a wireless transmission path, performs demodulation processing adapted to the above-described modulation method, and converts the pulse distortion indicating the training pattern described above. Based on this, the transmission characteristics of the wireless transmission path are equalized to obtain the transmission information. Therefore, among the bits included in the bit string indicating such transmission information, the bits arranged at positions separated on the time axis with respect to the training pattern described above are bit error due to fading of the wireless transmission path. Is likely to accompany. However, with the transmitter 41,
The arrangement changing means 45 changes the arrangement of the bit or partial bit string for which such a bit error should be avoided to the head of the bit string or in the vicinity thereof, and the receiver 43.
Then, the processing unit 47 restores the arrangement of the bit string obtained by performing the demodulation processing described above, or performs information processing suitable for the arrangement.

That is, there is no redundancy, the amount of processing that should be activated in response to a bit error is large, or the bit or partial bit string that cannot necessarily perform complete adaptive processing for that bit error is close to the training pattern. Since the data is arranged and transmitted at a position, the reception process is stabilized while allowing a bit error due to fading.

[0025]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 5 is a diagram showing an embodiment corresponding to the invention described in claim 1.

In the figure, an analog signal is given to the input of the A / D converter 51, and its output is connected to the transmitting antenna 53 via the transmitter 52. Reception antennas 54 ₁ and 54 ₂ forming a wireless transmission path with the transmission antenna 53
Are connected to the antenna terminals of the receiver 55, and their outputs are connected to the parallel inputs of the D / A converter 56. D /
An analog demodulated signal is obtained at the output of the A converter 56.

Regarding the correspondence relationship between this embodiment and the block diagram shown in FIG. 1, an A / D converter 51 and a transmitter 52 are shown.
And the antenna 53 corresponds to the transmitter 11 and the antenna 5
4 _1, 54 _2, the receiver 55 and D / A converter 56 corresponds to the receiver 13, the transmitter 52 corresponds to the arrangement change means 15, receiver 55 corresponds to the processing means 17.

FIG. 6 is a diagram for explaining the operation of this embodiment. The operation of this embodiment will be described below with reference to FIGS. The A / D converter 51 takes in an analog signal indicating a voice or an image and converts it into digital information having a word length of a plurality of bits (here, “4” for simplicity) at a predetermined cycle. The transmitter 52 generates a frame by taking in such digital information and arranging the bits of the higher order in advance in chronological order,
The carrier wave signal is modulated with the modulated wave signal indicating the frame and transmitted to the above-mentioned wireless transmission path via the antenna 53. It should be noted that the above-described higher-order bits are, for example, those obtained from an analog signal indicating a voice or an image, and the weight of the multivalued information indicating the amplitude value of the voice or the brightness of pixels forming the image is Indicates a large single or multiple bits.

On the other hand, in the receiver 55, the antennas 54 ₁ ,
The received wave is picked up via the one having a large received electric field level out of 54 ₂ and demodulation processing is performed to obtain the above-mentioned frame, and then the above-mentioned digital information is restored based on the configuration of the frame. The D / A converter 56 takes in the digital information restored in this way and obtains the demodulated signal described above.

By the way, since the electric field strength of the received wave taken in by the receiver 55 decreases as time elapses from the reception timing of the first bit of the frame, it is arranged in the latter half of the frame as shown in FIG. The bit (symbol) has a higher bit error rate.

However, the transmitter 52, as described above,
Of these bits, the higher order bits are placed in advance in the frame. Therefore, of the bits included in the digital information reconstructed by the receiver 55, the higher-order bits have a lower bit error rate as compared with the case of being arranged in the latter half of such a frame. Since the bits of the lower order are arranged in the latter half of the frame, the probability that a bit error will occur is higher for the lower bits.

Therefore, as shown in comparison with FIGS. 6 (a) and 6 (b), the disturbance of the waveform of the demodulated signal obtained at the output of the D / A converter 56 is reduced, and the bit generated in the radio transmission path is reduced. The amount of processing to be performed at the receiving end in response to the deterioration of data transmission quality caused by an error and the bit error is suppressed.

FIG. 7 is a diagram showing an embodiment corresponding to the invention described in claim 2. In FIG. In the figure, of the two fields that make up a frame, the information in the first field located at the beginning of the frame is connected to the first input of the transmitter 72 via the encoder 71 ₁ and is adjacent to that field. The information in the second field is connected to the second input of the transmitter 72 via the encoder 71 ₂ . The output of the transmitter 72 is connected to the antenna 53, and the receiving antennas 54 ₁ and 54 ₂ forming a wireless transmission path with the transmitting antenna are connected to the antenna terminal of the receiver 73. 2 of receiver 73
Of the two outputs, the first output is connected to the input of the decoder 74 ₁ and the second output is connected to the input of the demodulator 74 ₂ . At the outputs of the decoders 74 ₁ and 74 ₂ , the information corresponding to the above-mentioned first field and second field, respectively, is obtained.

The present embodiment and the block diagram shown in FIG.
The correspondence relationship between ₁, 71₂, Transmitter 7
2 and the antenna 53 correspond to the transmitter 21, and the antenna
54 ₁, 54₂, Receiver 73 and decoder 74₁, 74₂
Corresponds to the receiver 23.

The operation of this embodiment will be described below. The encoder 71 ₁ takes in the information of the first field arranged at the beginning of the frame, and has a code length of 31 bits and a sequence capable of error correction of a maximum of 1 bit for 26 information bits (hereinafter, for simplicity, " (31,26) Series ”.) B
CH (Hamming) encoding processing is performed. Also, the encoder 72
₂ is a sequence in which the information of the second field adjacent to the above-mentioned first field is fetched and error correction of up to 2 bits can be performed for 21 information bits with a code length of 31 bits. , 21) sequence ”).

The transmitter 72 takes in the error correction code generated by the encoders 71 ₁ and 71 ₂ by performing such BCH coding processing, and arranges it in the first field and the second field, respectively, to generate a frame. To do. Further, the transmitter 72 modulates the carrier wave signal with the modulated wave signal indicating the frame generated in this way, and the antenna 5
3 to the above-mentioned wireless transmission path.

On the other hand, in the receiver 73, the antennas 54 ₁ ,
Of the 54 ₂ , the received wave is taken in through the one having a large received electric field strength, and demodulation processing is performed to reproduce the above-mentioned frame, and based on the structure of the frame, the first field and the second field described above are added. The arranged error correction code is restored. The decoder 74 ₁ takes in the error correction code thus restored, which corresponds to the first field, and performs a decoding process adapted to the (31,26) sequence. Further, the decoder 74 ₂ takes in the error correction code thus restored, which corresponds to the second field, and performs a decoding process adapted to the (31,21) series.

By the way, the electric field strength of the received wave taken in by the receiver 73 generally decreases as time elapses from the reception timing of the first bit of the frame, as shown in FIG.
As shown in, the field arranged in the latter half of the frame has a higher bit error rate.

However, the encoder 71 ₁ encodes the information of the first field to be placed at the beginning of the frame by a sequence capable of error-correcting up to 1 bit out of 31 bits, and succeeding to the first field. The information in the second field is encoded by a sequence that can error-correct up to 2 bits out of 31 bits.

That is, even if the second field is received with a lower electric field strength than the first field and a bit error occurs, the second field can correct more error bits than the first field. Since it is transmitted by applying the coding method, the bit error is corrected with higher accuracy as compared with the conventional example in which the coding method having the error correction capability adapted to the arrangement of such fields is not applied. To be done.

Therefore, according to this embodiment, the deterioration of the data transmission quality due to the bit error and the processing amount to be performed at the receiving end in response to the bit error are significantly suppressed.

FIG. 8 corresponds to the invention described in claim 3.
It is a figure which shows an Example. In the figure, configure the frame
Placed at the beginning of the frame of the two fields
The information of the first field stored is the encoder 81.₁Input and
Encoder 81₂These encoders are fed to one input of
Output of the transmitter 82 is respectively a first input and a second input of the transmitter 82.
Connected to modulation input. In addition, the first frame on the frame
The information of the second field adjacent to the field is the encoder 81.
₂The other input and encoder 81 ₃Given to the input of
Encoder 81₃The output of is connected to the third modulation input of transmitter 82.
Continued. The control input of the transmitter 82 includes a receiver (not shown).
The receiver gives an RSSI signal indicating the received electric field strength.
You. The output of the transmitter 82 is connected to the antenna 53,
A receiving antenna that forms a wireless transmission path with the transmitting antenna
Na 54₁, 54₂Is the first antenna terminal of the receiver 83
And a second antenna terminal. Receiver 83-3
The first of the two outputs is the decoder 84₁Connected to the input of
And the second output is the decoder 84₂And transmission mode detector
85 inputs. The third output of the receiver 83 is
Decoder 84₃Connected to the input of Decoder 84₁Output
And decoder 84₂The first output of selector 86₁Pair of
Corresponding input to the decoder 84₂The second output of
And decoder 84₃Output of selector 86₂Corresponding input of
Connected to. The output of the transmission mode detector 85 is a selector
86₁, 86₂Connected to the select inputs of these select
The output of the
The restored information is obtained corresponding to the two fields.

The present embodiment and the block diagram shown in FIG.
The correspondence relationship between ₁, 81₂, 81₃,
The transmitter 82 and the antenna 53 correspond to the transmitter 21,
Antenna 54₁, 54₂, Receiver 83 and decoder 84
₁, 84₂, 84₃Corresponds to the receiver 23, fading
Cycle detecting means 31, coding range changing means 33 and code
The conversion method changing means 35 corresponds to the transmitter 21, and the transmission mode
Detector 85 and selector 86₁, 86₂Is the receiver 23
Corresponding to.

The operation of this embodiment will be described below. The encoder 81 ₁ takes in the information of the above-mentioned first field,
BCH of (31,26) series with 31 bit code length and maximum 1 bit error correction for 26 information bits
Encoding processing is performed. Further, the encoder 82 ₂ takes in the information of the above-mentioned first field and second field,
(31,21) -series BCH with a code length of 31 bits and error correction of up to 2 bits for 21 information bits
Encoding processing is performed. Further, the encoder 81 ₃ takes in the information of the second field described above, and can perform error correction of up to 3 bits for 16 information bits with a code length of 31 bits, and a BCH encoding process of (31,16) series. Give.

The transmitter 82 detects the fading pitch associated with the received wave by taking in the RSSI signal supplied from a receiver (not shown) and performing a predetermined calculation on the amplitude of the signal. As for the procedure of such calculation, for example, "Takenaka, Nakatsu: Moving speed estimation method by detecting difference in reception level, 1993 Autumn Meeting of the Institute of Electronics, Information and Communication Engineers" and "Takenaka: Moving speed estimation using receiving diversity" , 1993 Spring Meeting of the Institute of Electronics, Information and Communication Engineers ”can be applied.

Further, the transmitter 82 judges the magnitude relationship between the fading pitch thus detected and 20 Hz, and if the former is less than the latter, the encoder 81 ₂ performs the above-mentioned encoding processing. The error correction code generated by the above is taken in, arranged in the first field and the second field based on the frame structure shown in FIG. 9, and the bit M indicating the transmission mode arranged prior to these fields in the frame. A frame is generated by setting the logical value to "0". On the contrary, when the former exceeds the latter, the BCH code generated by the encoding process performed by the encoder 81 ₁ is arranged in the first field, and the BCH code generated by the encoder 81 ₃ is generated. A frame is generated by placing the error correction code in the second field and setting the logical value of the bit M described above to "1".

Further, the transmitter 82 modulates a carrier wave signal with a modulated wave signal indicating a frame generated based on any one of the above-mentioned two procedures, and transmits the modulated carrier wave signal to the above-mentioned radio transmission path via the antenna 53. To do.

On the other hand, in the receiver 83, the antennas 54 ₁ ,
The received wave is taken in through 54 ₂ having a high received electric field strength, and demodulation processing is performed to reproduce the above-mentioned frame. Further, the receiver 83 gives the frame thus reproduced to the decoder 84 ₂ and the transmission mode detection unit 85, and based on the structure of the frame, the bit string arranged in the first field and the second field described above. Are separated and supplied to decoders 84 ₁ and 84 ₃ , respectively.
Decoders 84 ₁ and 84 ₃ are encoders 81 ₁ and 81 ₃ , respectively.
The transmission information corresponding to the first field and the second field is restored by performing the decoding process that is adapted to the encoding process performed by. In addition, the decoder 84 ₂ is the encoder 81
_By performing a decoding process adapted to the encoding process performed by 2, the transmission information of the first field and the second field is collectively restored. Furthermore, the transmission mode detection unit 85
Takes in the frame reproduced by the receiver, extracts the bit M based on the frame structure shown in FIG. 9, and supplies it to the selectors 86 ₁ and 86 ₂ .

When the logical value of the bit M extracted in this way is "0", the selector 86 ₁ outputs the decoder 8
The transmission information of the first field restored by 4 ₂ is selected. On the contrary, when it is “1”, the transmission information restored by the decoder 84 ₁ is selected. Also, the selector 8
6 ₂ selects the transmission information of the second field restored by the decoder 84 ₂ when the logical value of the bit M similarly extracted is “0”, and conversely is “1” , The transmission information restored by the decoder 84 ₃ is selected.

By the way, the received electric field strength of the received wave taken in by the receiver 83 generally decreases as the time elapses from the start timing of the frame described above, and the bit error rate becomes as shown in FIG. The higher the value is in the field located in the latter half of the.

However, when the fading pitch is large enough that the second field is received with a lower electric field strength than the first field, the transmission information of the first field is error-corrected up to 1 bit at the transmitting end. Is performed, the transmission information of the second field is subjected to a sequence encoding process capable of error correction up to 3 bits, and such field-by-field encoding is performed. A transmission frame is configured by adding a bit M (= 0) indicating a combination of processing. On the contrary, when the fading pitch is so small that the first field and the second field are received without a large electric field strength difference, the transmission information of the first field and the second field is 2 at the transmitting end. A transmission frame is configured by performing a coding process of a series capable of error correction up to bits and adding a bit M (= 0) indicating a combination of such coding processes. Further, at the receiving end, a receiving process adapted to such a structure of the transmission frame is switched and applied based on the logical value of the bit M.

As described above, according to this embodiment, the distribution of the bit error rate in the frame is accurately predicted based on the fading pitch, and it is determined that the bit error rate is likely to fall below a predetermined threshold value. In this case, encoding methods having different error correction capabilities are applied to the first half and the second half of the frame in combination, and on the contrary, when it is determined that such a possibility is low, the desired correction capability is obtained. The coding method is applied to the entire frame, and information indicating the mode of application of such a coding method is added to the frame and transmitted.

That is, even if a bit error occurs due to fading, the second field is transmitted by applying an encoding method capable of correcting more error bits than the first field. The bit error is corrected with higher accuracy as compared with the conventional example in which the coding method having the error correction capability adapted to such field arrangement is not applied.

Therefore, according to the present embodiment, the deterioration of the data transmission quality caused by the bit error occurring in the wireless transmission path and the amount of processing to be performed at the receiving end in response to the bit error are significantly suppressed. .

Although the BCH coding method is applied in the embodiments corresponding to claims 2 and 3 described above, the present invention is not limited to such a coding method and the transmission information is constant. If there is no restriction on the code length such as a block code that is encoded into a sequence of length, or there is no restriction on the compatibility with the length of transmission information, for example, a convolutional code or the like can be applied. .

As an example of applying such a convolutional code, for example, as shown in FIG. 10, information to be transmitted by a unit frame (here, it is assumed that it is given as a 96-bit bit string for simplicity). Tail bit (here, it is assumed to be given as a 4-bit bit string for simplicity), and a desired constraint length (for example, “4”) and a coding rate (for example, “1 /”).
3 ”), the convolutional coding process is performed, and the convolutional code generated by such a coding process is interleaved to disperse the bit error generated in the wireless transmission path and perform the punctured coding process. There is a configuration for increasing the coding rate to generate a frame. With such a configuration, when the fading pitch detected based on the RSSI signal is large, the distribution of bits and symbols to be thinned out in the process of the punctured encoding process described above is biased toward the second half of the frame, and conversely the fading is performed. When the pitch is small, a similar effect can be obtained by making such a distribution uniform over the entire frame.

In the embodiments corresponding to the inventions described in claims 1 to 3, the receivers 55, 73 and 83 are provided with
Although the antenna switching diversity method is applied to the _two antennas 54 ₁ and 54 ₂ , the invention is not limited to such a configuration, and the antennas are switched similarly by comparing the received electric field strengths of three or more antennas. A diversity method can also be applied.

In the embodiments corresponding to the inventions described in claims 2 and 3, the transmission information is divided into frames and wirelessly transmitted, but the present invention is not limited to such frames. For example, it is also applicable to wireless transmission by a cell relay system.

Further, in the embodiments corresponding to the inventions described in claims 2 and 3, the single information composed of a plurality of bit strings having different weights is arranged in any field included in each frame. However, the present invention is not limited to a field having such a configuration, and is similarly applicable to a case where a plurality of pieces of information having bit strings having different weights and different word lengths are arranged in the field. Is.

Further, in the embodiments corresponding to the inventions described in claims 2 and 3, each frame is composed of a maximum of two fields, and an individual error correction coding system is applied to these fields. However, the present invention is not limited to such a configuration, and a frame is composed of three or more fields, and it is also possible to individually apply an arbitrary error correction coding method to these fields.

Further, in the above-mentioned embodiment, the combination of the decoding outputs adapted to the transmission mode M is selected via the transmission mode detecting section 85 and the selectors 86 ₁ and 86 ₂ , but the present invention is not limited to this. When the reception process adapted to M is directly performed, such a selection process may not be performed.

FIG. 11 is a diagram showing an embodiment corresponding to the invention described in claim 4. In FIG. In the figure, parts having the same functions and configurations as those shown in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted here.

The difference between the present embodiment and the embodiment shown in FIG. 5 is that a transmitter 91 is provided instead of the transmitter 52, an antenna 54 ₂ is not provided, and a receiver 55 is provided instead of the receiver 55. 92 is provided.

Regarding the correspondence between this embodiment and the block diagram shown in FIG. 4, an A / D converter 51 and a transmitter 91 are shown.
And the antenna 53 corresponds to the transmitter 41, and the antenna 5
4 _1, 54 _2, the receiver 55 and D / A converter 56 corresponds to the receiver 43, the transmitter 91 corresponds to the arrangement change means 45, receiver 92 corresponds to the processing means 47.

The operation of this embodiment will be described below. A / D
The converter 51 takes in an analog signal indicating a voice or an image and converts it into digital information having a word length of a plurality of bits (here, “4” for simplicity) at a predetermined cycle. The transmitter 91 takes in such digital information, first modulates the carrier signal with the training signal, and transmits the carrier signal to the wireless transmission path via the antenna 53. Further, when the transmitter 91 completes the transmission of the training signal, the transmitter 91 generates a serial bit string by precedingly extracting the higher-order bits of the bit string forming the digital information described above, and the bit string. The carrier wave signal is modulated by the modulated wave signal indicating the above and transmitted in the same manner. It should be noted that the above-described higher-order bits are, for example, those obtained from an analog signal indicating a voice or an image, and the weight of the multivalued information indicating the amplitude value of the voice or the brightness of pixels forming the image is Large single or multiple bits.

On the other hand, the receiver 92 demodulates when the received wave is taken in via the antenna 54 ₁ , first extracts the training signal described above, and then performs a predetermined process on the training signal, thereby transmitting from the transmitter 91. Antenna 5
The transmission characteristics of the wireless transmission path reaching the receiver 92 via ₃ , 54 ₁ and 54 ₂ are equalized. Furthermore, the receiver 11
Continues a similar demodulation process under such equalization to extract a subsequent bit string from the training signal described above.

The D / A converter 56 takes in the bit string thus extracted and obtains the above-mentioned demodulated signal.
For such a bit string, the bit received with a delay from the time point when the transmission characteristics are equalized by the training signal, the transmission characteristics may change due to fading, so the bit error rate is Get higher

However, the transmitter 91, as described above,
Of these bits, the higher order bits are transmitted first. Therefore, of the bits constituting the bit string reconstructed by the receiver 92, the higher-order bits have a lower probability of causing a bit error than the subsequent lower bits.

Therefore, the disturbance of the waveform of the demodulated signal obtained at the output of the D / A converter 56 is reduced, and the processing to be performed at the receiving end in response to the deterioration of the data transmission quality caused by the bit error and the bit error. Processing amount is suppressed.

In each of the above-mentioned embodiments, the modulation method applied to the transmitter is not shown, but if the desired transmission quality and transmission rate are realized while adapting to the characteristics of the wireless transmission path. For example, the carrier signal may be amplitude-modulated, frequency-modulated, or phase-modulated in bit units.
Amplitude / phase modulation based on a desired signal space diagram may be performed for each symbol unit including a plurality of bits.

In the embodiments corresponding to the inventions described in claims 1 and 4, the analog signal indicating the transmission information is digitally converted through the A / D converter. The present invention is not limited to such analog signals, but can be applied to the case where the transmission information is directly given as digital information.

Further, in the embodiments corresponding to the inventions described in claims 1 and 4, the importance of the transmission information (the degree of the request to avoid the bit error) is set in two stages. The invention is not limited to such a configuration, and may be set in three or more stages, for example.

Further, in such a case, with respect to the relative arrangement of the bits and the partial bit strings with respect to the head of the frame and the end of the training pattern, the bit error rate is equal to or higher than a desired lower limit value according to the importance. If it is secured in the order, the order of importance does not have to be followed.

[0074]

As described above, according to the first aspect of the present invention, among the bits and bit strings forming a frame or cell, there is a high demand for avoiding the occurrence of a bit error caused by fading. Wireless transmission is performed by arranging the frame or the cell at the head or in the vicinity thereof.

That is, there is no redundancy, the amount of processing to be activated in response to a bit error is large, and the bit or partial bit string that cannot be completely adapted to the bit error is used as a frame or cell bit. It can be placed at or near the beginning.

According to the second aspect of the invention, as an error correction coding method for individual transmission information to be error-correction-coded and arranged in a frame or cell to be transmitted, the frame or cell is separated from the head of the frame or cell. The error correction coding method in which the number of correctable bits is larger is applied to perform wireless transmission.

That is, since it is possible to perform error correction on a larger number of bits in a field in which bit errors are more likely to occur due to fading, transmission information having no redundancy can be transmitted with high accuracy.

In the invention described in claim 3, in the invention described in claim 2, the bit error rate is predetermined on each frame or cell based on the average period of fading and the amplitude distribution of the fading. A position that can be regarded as a threshold is set as a boundary of the application range of each error correction coding method, and identification information indicating a combination of error correction coding methods adapted to the boundary is added to the transmission information.

That is, since a combination of error correction coding methods that are dynamically applied according to the state of the wireless transmission path is set and the combination is transmitted to the receiver, transmission information having no redundancy is transmitted. It is transmitted with higher accuracy.

In the invention described in claim 4, the training pattern is added to the head of the bit string indicating the transmission information and wirelessly transmitted. However, bit errors should be avoided among the bits and partial bit strings forming the bit string. The one with the highest demand is placed at or near the beginning of the bit string.

That is, for such a bit or partial bit string, the probability that a bit error will occur due to a change in the transmission characteristic of the wireless transmission path can be suppressed to a small value.
Transmission information without redundancy is transmitted with high accuracy.

Therefore, in the radio transmission system to which these inventions are applied, the data transmission quality is improved while allowing the bit error caused by fading, and the reception process is stabilized. In addition, the possibility that a large amount of processing will be activated in response to a bit error, or a processing that cannot necessarily be perfect countermeasures will be significantly suppressed, and efficiency and reliability related to maintenance and operation will be reduced. And is enhanced.

[Brief description of drawings]

FIG. 1 is a principle block diagram of the invention according to claim 1.

FIG. 2 is a principle block diagram of the invention described in claim 2.

FIG. 3 is a principle block diagram of the invention according to claim 3;

FIG. 4 is a principle block diagram of the invention according to claim 4;

5 is a diagram showing an embodiment corresponding to the invention described in claim 1. FIG.

FIG. 6 is a diagram for explaining the operation of this embodiment.

FIG. 7 is a diagram showing an embodiment corresponding to the invention described in claim 2.

FIG. 8 is a diagram showing an embodiment corresponding to the invention described in claim 3;

FIG. 9 is a diagram showing a configuration of a frame applied to this embodiment.

FIG. 10 is a diagram illustrating an operation when a convolutional coding method is applied to the present embodiment.

FIG. 11 is a diagram showing an embodiment corresponding to the invention described in claim 4;

FIG. 12 is a diagram showing a distribution of bit error rates according to fading pitches.

[Explanation of Codes] 11, 21, 41, 52, 72, 82, 91 Transmitter 13, 23, 43, 55, 73, 83, 92 Receiver 15, 45 Arrangement changing means 17, 47 Information processing means 31 Fading cycle Detecting means 33 Coding range changing means 35 Coding method changing means 37 Coding method adapting means 51 A / D converter 53, 54 Antenna 56 D / A converter 71, 81 Encoder 74, 84 Decoder 85 Transmission mode Detector 86 Selector

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H04L 1/06

Claims (4)

[Claims] 1. A transmitter that modulates and transmits a carrier signal by a logical value of a bit string or a combination of the logical values of bit strings individually configuring a single frame or a plurality of frames or cells containing transmission information, and a transmitter from the transmitter. Received waves arriving via a wireless transmission path are received by applying an antenna switching diversity method to each frame or cell, and demodulation processing adapted to the modulation method is applied to obtain a bit string included in the frame or cell. In a wireless transmission system including a receiver, in the transmitter, the arrangement of bits or partial bit strings for which a bit error is required to be avoided in the bit string is changed to the head of the frame or the cell or the vicinity thereof. And an arrangement changing unit, wherein the receiver includes a bit string obtained by performing the demodulation process. Te, restore the arrangement that has been changed by the arrangement change means, or wireless transmission system, characterized in that it comprises a processing means for performing processing adapted to the arrangement. 2. A frame or cell is generated by individually performing error correction coding on single or a plurality of pieces of transmission information and serially arranging the information, and a logical value of a bit string constituting the frame or cell or a combination of the logical values thereof. A transmitter that modulates and transmits a carrier signal by means of, and receives a received wave that arrives from the transmitter via a wireless transmission path by applying the antenna switching diversity method to the frame or cell unit, and to the modulation method. In a wireless transmission system including a receiver that performs the demodulation process adapted and the decoding process adapted to the error correction encoding system to obtain the single or a plurality of transmission information, the transmitter includes: As a method, the number of correctable bits is larger when the position where the codeword is to be arranged is farther from the beginning of the frame or the cell. A wireless transmission method characterized in that a threshold error correction coding method is applied. 3. The wireless transmission system according to claim 2, wherein the transmitter sets the electric field strength levels of the received waves arriving from the wireless station in which the receiver is arranged via a wireless transmission path in chronological order. Taking in frequency analysis, fading period detection means for obtaining the average period of fading associated with the received wave, and monitoring the average period obtained by the fading period detection means, to the average period and the amplitude distribution of the fading A coding range variable means for determining a position at which the bit error rate on the frame or cell can be regarded as a predetermined threshold value, and setting the boundary of the applicable range of each error correction coding method at the position; The combination of the methods is variably set according to the boundary set by the encoding range changing means, and the identification information indicating the combination is set. And a coding system variable means to be added to the cell, and the receiver is provided with a combination of error correction coding systems to be applied to the decoding process based on the identification information obtained by the demodulation process. A wireless transmission system comprising a decoding system adaptation means for variably setting. 4. A transmitter that adds a training pattern to the beginning of a bit string indicating transmission information, modulates a carrier signal by a logical value of the training pattern and the bit string, or a combination of the logical values, and transmits the modulated carrier signal. From a received wave arriving via a wireless transmission path from the received signal, performs demodulation processing adapted to the modulation method, and equalizes the transmission characteristics of the wireless transmission path based on the distortion of the pulse indicating the training pattern. In the wireless transmission system including a receiver that obtains the transmission quotient under the equalization thereof, the transmitter has a bit string or a partial bit string that has a high demand for avoiding a bit error in the bit string. The receiver includes a placement changing unit that changes the bit sequence to the beginning or in the vicinity thereof. For preparative column, it restores the arrangement that has been changed by the arrangement change means, or wireless transmission system, characterized in that it comprises a processing means for performing processing adapted to the arrangement.