JPH08125584A - Digital radio wave communication equipment - Google Patents

Abstract

PURPOSE: To shorten the processing time of interlieving and to prevent error diffusion by repeatedly transmitting a same frame with plural segments where an error detecting code is added two times by means of different frequencies at a transmission side. CONSTITUTION: In a transmitting device, input data is delimited into the segments consisting of prescribed number of symbols and segmented and the error detecting code is added to the individual segments. A frame generating circuit 4 generates one frame from the prescribed number of segments with the error detecting code and a frame repeating two-transmission circuit 5 synchronizes with a hopping timing so as to transmit after two-time repetition. Then, the respective framed are digitally modulated in order by a digital modulating circuit 6 and transmitted from an antenna with a radio wave transmitting circuit 7. In this case, the radio wave transmitting circuit 7 is controlled so as to permit the center frequency of transmission carrier wave to be hopped in terms of the pseudo random number in a hopping control circuit 9. In result, the interlieving processing time of data is shortened while dealing a burst error caused by interference and the transmission error is extremely reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency hopping digital radio communication device.

[0002]

2. Description of the Related Art In the field of mobile communication, how to effectively use finite frequency resources has become an important technical issue. Therefore, GMSK (Gaussian Min)
It is an abbreviation for "imm Shift Keying", and after the input signal is band-limited by a Gaussian filter, M
SK modulation) or π / 4 shift QPSK (Q
uadrature Phase Shift Key
ing, which is an abbreviation for ing and is a modulation method in which four orthogonal phases are used to carry information) has been established.

On the other hand, conversely, the occupied bandwidth of the transmission signal is set to ASK (Amplitude Shift Keyi).
ng) and PSK (Phase Shift Keyin)
g) Broadening compared to (eg, transmitting a band signal of several Hz such as voice in a band of about 10 MHz) to spread the spectrum with a communication system with excellent noise resistance and interference resistance. Communication method (abbreviated as SS method)
There is a communication method called. This communication system has the same S / N ratio when the occupied bandwidth of a signal is narrowed by using multilevel modulation.
This is a technology that was conceived to solve the drawbacks such as poor transmission error rate under specific conditions and weakness against co-channel interference from other communication systems that use the same radio frequency. Also, it is used in the field of wireless communication using a transmission path with bad conditions such as a wireless LAN used in a place where there is a lot of noise interference. In addition,
As a frequency bandwidth to be used, a diffusion bandwidth of several hundred kHz to several hundred MHz is generally used.

In the spread spectrum communication system, the information energy of the signal on the transmitting side is dispersed and transmitted in a wide band,
At the receiving side, this is reassembled into the original narrow band to improve the anti-jamming property, the multi-wave interference property, and the confidentiality. This is because the spectrum density of the signal becomes extremely low, so it becomes impossible for the ordinary receiver to distinguish the signal,
Furthermore, even if there is an interfering interference wave in the transmission band of the signal, it is extremely unlikely to be affected.

In addition to the spread spectrum method, code division multiple access (CDMA) is also available.
iple Access) is available. CDM
A is FDMA (Frequency Division Multiple Acces
s) and TDMA (Time Division Multiple Access), it is one of the multiple access methods, but it uses both frequency and time, and the channel is identified by a unique code sent over the signal. Has become. For this,
It becomes possible for multiple users to use the same frequency band at the same time, but as a result, by superimposing the code on the transmission signal, the frequency component of the signal spreads over the entire band.

[0006] By the way, a typical method of spread spectrum communication is direct spread (DS) in which a normal digitally modulated signal is spread over a wide band with a high-speed (for example, several Mbps) pseudo noise signal (also called spread code). ; Direct Seque
frequency hopping (FH; Frequency Hopping) in which a carrier frequency is switched at high speed by pseudo-random number modulation using a frequency synthesizer and modulated to spread the signal by hopping (leaping) the frequency in a wide band.
There is a method.

Of these, particularly in the FH system, there is a near-far problem without performing special transmission power control (that is, when a communication partner is located far away, another communication station located nearby issues the problem. It has characteristics suitable for mobile communication, such as that it is unlikely that communication in progress will be difficult due to the influence of radio waves. Then, the order of frequency hopping in this FH method is set to be random,
The receiving side performs frequency conversion by oscillating in the same order as the hopping order on the transmitting side, performs BP (band pass) processing, and then detects and demodulates the signal.

Further, in the FH system, a fast frequency hopping (FFH; Fast Frequency Hopp) in which a switching speed of a carrier frequency is faster than or equal to a transmission code speed.
ing) system and a slow hopping (SFH) system in which a plurality of codes are transmitted in one frequency slot, which is slower than the transmission code rate. Of these, the SFH method, in particular, can be said to be relatively easy to realize in terms of a circuit, because the switching speed of the carrier frequency is slower than the FFH method. In addition, since multiple bits are grouped and transmitted in one time slot, the conventional TD
It has good compatibility with the MA (Time Division Multiple Access) method and is currently used in GSM (Global System for Mobile C).
Ommunication, or Pan-European mobile communication system), has also been incorporated into cellular telephone standards.

[0009]

However, the above SFH
In the system, when a certain frequency slot is disturbed by an interference wave, a burst error occurs in the transmission data in the hopping period using the frequency slot. Further, even when there is another similar SFH communication device, a burst error occurs during a period in which the communication device and the used frequency hit (a state where signals compete with each other at a certain frequency).

Therefore, in the SFH method, in order to relieve the data error due to such co-channel interference,
Generally, error correction means are introduced. In this case, since data errors tend to occur in bursts,
In order to effectively operate such an error correction means, it is a method of interleaving data (that is, rearranging transmission data and transmitting them with time separation so as to disperse errors that occur collectively. ) Is done.

However, such data interleaving causes a delay in data processing, and particularly in the case of a cordless telephone that communicates voice signals bidirectionally, it appears as a delayed side tone (echo). Therefore, it is inevitable that the caller feels unnatural. For example, in GSM described above, a convolutional code is adopted as an error correction code and data interleaving is performed, but the delay time due to interleaving in this case is 37 msec. For this reason, in order to deal with the generation of delayed sidetone, an echo canceller (a device that cancels the generated echo by artificially adding a signal that is the exact opposite of the returned echo, It is designed to be inserted between the parts).

Further, in order to reduce the delay due to such interleaving, it is sufficient to shorten the frame length (that is, the time length of the frequency slot), but in such a case, the frequency hopping speed increases. ,
Increasing the cost and increasing the size of the frequency synthesizer cannot be avoided. Furthermore, when an error exceeding the error correction capability occurs, such interleaving may rather spread the error over a wide range.

The present invention has been made in view of the above circumstances, and while coping with a burst error caused by interference, prevents an increase in processing delay time due to data interleaving and spread of an error to ensure stable communication. It is an object of the present invention to provide a digital radio communication device of a frequency hopping system that enables the above.

[0014]

In order to achieve the above object, the invention according to claim 1 is a frequency hopping system for transmitting a digital signal by pseudo-randomly switching a transmission frequency between a transmitting device and a receiving device. In the digital wireless communication device of the method, the transmitting device divides the input data into segments consisting of a predetermined number of symbols and cuts out the segments, and an error detection code is added to each of the segmented segments. Error detection code adding means, frame generation means for generating one frame with a predetermined number of segments to which the error detection code is added, and a predetermined number of frames are repeatedly transmitted twice in synchronization with hopping timing. Frame repeated transmission means and digital modulation for sequentially digitally modulating each frame to be transmitted A step, a wireless transmission means for wirelessly transmitting each of the digitally modulated frames in order, a transmission side hopping control means for controlling the wireless transmission means so that the center frequency of a transmission carrier wave is hopped in a pseudo-random number, Timing pulse supply for giving a timing pulse to each of the segment cutting means, the error detection code adding means, the frame generating means, the frame repeating transmitting means, and the transmitting side hopping control means so that they operate in synchronization with the hopping timing. Means for receiving the radio signal from the communication partner, the radio receiving means, and the radio receiving means, in synchronization with the transmission-side hopping timing, the center frequency of each reception carrier, in order. The receiving side hopping control means for controlling to return to the reference frequency, and the wireless receiving means. Digital demodulation means for converting the received signal into digital data, frame extraction means for extracting a predetermined number of frames from the demodulated data, and determination as to whether or not the extracted predetermined number of frames are repeated twice Frame determination means for
From each of the predetermined number of repeated frames, segment extraction means for extracting a segment to which an error detection code is added, segment determination means for determining whether the extracted segment is valid, or demodulated The frame extraction means, the frame determination means, the segment extraction means, the segment determination means, and the receiving-side hopping control means operate so as to operate in synchronization with the transmitting-side hopping timing. And a timing pulse supplying means for applying a timing pulse to the means.

Further, the invention according to claim 2 is the digital radio communication apparatus according to claim 1, wherein the frame repeating transmitting operation by the frame repeating transmitting means in the transmitting device and the frame by the frame extracting means in the receiving device. The extraction operation is interlocked with the generation of the hopping frequency sequence by the transmission-side hopping control means in the transmission device.

The invention according to claim 3 is the digital wireless communication apparatus according to claim 1 or 2,
It is characterized in that the frame extracting means determines a division of received data consisting of a predetermined number of frames based on the synchronization information from the timing pulse providing means.
Further, in the invention described in claim 4, in the digital wireless communication apparatus according to claim 1 or 3, the frame determination means is repeated twice based on the synchronization information from the timing pulse providing means. It is characterized by determining a predetermined number of frames.

The invention according to claim 5 is the digital radio communication apparatus according to claim 1 or 4, wherein:
The segment determining means performs error detection on the m-th segment in the n-th frame of each of the predetermined number of frames repeated twice, and determines the validity of the segment by performing error detection using the added error detection code. It is characterized by doing.

Further, in the invention described in claim 6, in the digital radio communication apparatus according to claim 5, the segment determination means has an error in both the m-th segment in the corresponding n-th frame. When not detected,
The data of the segment shall be output as valid,
When an error is detected in both segments, the data in the segment is invalidated and an invalid flag is output.

[0019]

According to the configuration of the invention according to claim 1, in the digital wireless communication apparatus of the present invention, the frequency of the hopping method is such that the transmission frequency is switched between the transmitting and receiving apparatuses in a pseudo-random number manner to transmit the digital signal. Communication takes place. In this case, in the transmitting device, first, the segment cutout unit divides the input data into segments each including a predetermined number of symbols and cuts out the segments. Further, the error detection code adding means adds an error detection code to each of the cut out segments.

Next, the frame generation means generates one frame with a predetermined number of segments to which the error detection code is added. Then, a predetermined number of frames are repeatedly transmitted twice in synchronization with the hopping timing by the frame repeating transmission means. Then, each frame to be transmitted is digitally modulated in order by the digital modulation means. Further, the wirelessly transmitting means sequentially wirelessly transmits the digitally modulated frames through the transmitting antenna. In this case, the transmission-side hopping control means controls the wireless transmission means so that the center frequency of the transmission carrier wave is hopped in a pseudo-random number.

Further, each of the segment cutting means, the error detection code adding means, the frame generating means, the frame repetitive transmitting means, and the transmitting side hopping control means is operated by the timing pulse providing means so as to operate in synchronization with the hopping timing. Timing pulses are provided to the means. On the other hand, in the receiving device, the wireless receiving means receives the wireless signal from the communication opposite device.
In this case, the receiving side hopping control means controls the radio receiving means so that the center frequency of each reception carrier wave returns to the reference frequency in order in synchronization with the transmitting side hopping timing. Then, the digital demodulation means converts the signal received by the wireless reception means into digital data. Further, the frame extracting means extracts a predetermined number of frames from the demodulated data.

Next, the frame determination means determines whether or not the extracted predetermined number of frames are repeated twice. Then, the segment extraction means extracts the segment to which the error detection code is added from each of the predetermined number of frames repeated twice. Further, the segment determination means determines whether or not the extracted segment is valid.

Further, symbol synchronization and frame synchronization are established from the demodulated data by the timing pulse providing means, and the frame extracting means, frame determining means, segment extracting means, segment determining means,
Then, a timing pulse is given to each unit of the receiving-side hopping control unit so that each unit operates in synchronization with the transmitting-side hopping timing.

Further, according to the configuration of the invention according to claim 2 above, in the digital wireless communication device according to claim 1,
The frame repeating transmission operation by the frame repeating transmitting means in the transmitting device and the frame extracting operation by the frame extracting means in the receiving device are linked with the generation of the hopping frequency sequence by the transmitting side hopping control means in the transmitting device. ing.

According to the third aspect of the present invention, in the digital wireless communication device according to the first or second aspect, the frame extracting means uses the synchronization information from the timing pulse providing means based on the synchronization information. , The delimiter of the received data composed of a predetermined number of frames is determined. Further, according to the configuration of the invention according to claim 4, in the digital wireless communication device according to claim 1 or 3, the frame determination means repeats twice based on the synchronization information from the timing pulse providing means. The determined number of frames that have been selected are determined.

According to the configuration of the invention according to claim 5, in the digital wireless communication device according to claim 1 or 4, the segment determining means makes it possible to detect each of a predetermined number of frames repeated twice. The m-th segment in the n-th frame is subjected to error detection by the added error detection code, and the validity of the segment is determined.

According to the structure of the invention according to claim 6, the digital radio communication device according to claim 5 is:
When an error is not detected in both the m-th segment in the corresponding n-th frame by the segment determination means, it is assumed that the data of the segment is output as valid, and an error is detected in both segments. If so, the invalid flag is output as the data of the segment is invalid.

As a result, the frame repeatedly transmitted from the transmitting device is received by the receiving device and the error of the corresponding segment is judged to determine the valid frame and output the data. Is possible.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing a circuit configuration on the transmission side of a digital wireless communication apparatus according to the present invention, which is basically a frequency hopping digital wireless transmission apparatus. On the transmission side, input data (transmission data) is converted into a symbol series by the data input circuit 1. The symbol sequence here means, in the case of binary transmission,
It is a bit string of "1, 0", and in the case of multi-value transmission, it is a code string composed of the multi-valued types of symbols. Subsequently, this symbol sequence is divided by the segment cutout circuit 2 into segments divided into a predetermined number of symbols, and an error detection code addition circuit 3 adds an error detection code (for example, CRC) to each segment. .

Next, the frame generation circuit 4 collects m (m ≧ 1) segments to which the error detection code is added to generate one frame. Further, the frame repeating circuit 5 collects n (n ≧ 1) frames and repeats the transmission twice. Subsequently, the transmitted frames are sequentially converted into a signal on a carrier wave by the digital modulation circuit 6 (usually FSK, PSK, etc. are adopted),
The data is transmitted to the communication opposite device through the wireless transmission circuit 7 and the transmission antenna 8 and is transmitted to the air. At this time, under the control of the hopping control circuit 9, the wireless transmission circuit 7 randomly hops the center frequency of the transmission carrier at every predetermined time (hopping cycle).

Further, the timing of segment segmentation,
Regarding the timing of adding the error detection code to the cut out segment, the timing of frame generation, the transmission timing of n frames, and the timing of frequency hopping, one hop is made every n frames according to the timing pulse supplied from the timing circuit 10. It is supposed to be synchronized. Then, the start of the two repeating frames by the frame repeating circuit 5 is controlled so as to be synchronized with a predetermined time slot in the hopping sequence (hopping pattern) generated by the hopping control circuit 9.

FIG. 2 is a block diagram showing the circuit configuration of the receiving side of the digital radio communication apparatus according to the present invention, which is basically a frequency hopping type digital radio receiving apparatus, and is shown in FIG. It is designed to be used in combination with a wireless transmission device. On the receiving side, the receiving antenna 100 → wireless receiving circuit 101 → digital demodulation circuit 10
The synchronizing circuit 109 establishes symbol synchronization and frame synchronization for the digital data demodulated through 2. Further, based on this synchronization information (timing information), the hopping control circuit 108 performs frequency control in synchronization with the transmission side, and the frame extraction circuit 103 outputs n symbol sequences output from the digital demodulation circuit 102. It is cut out in frame units.

Further, the synchronization circuit 109 detects a predetermined time slot in the demodulated hopping sequence, and based on this information, the frame determination circuit 104 delimits n frames which are repeatedly transmitted. decide. Further, the segment extraction circuit detects the error detection detection code added to each segment on the transmission side and extracts m segments.

Therefore, the valid segment determination circuit 106 performs error detection on the corresponding m segments in each of the n repeated frames using the error detection code, and validates the segment in which no error is detected. Then, the data is output from the data output circuit 107 of the next stage. When an error is detected in both, the data output circuit 107 outputs an invalid flag as an invalid segment. The data output circuit 107 is adapted to convert the data from the valid segment determination circuit 106 into a predetermined format and timing and output it.

FIG. 3 is a schematic diagram showing each data structure handled by the main circuit blocks of the digital wireless communication device shown in FIGS. 1 and 2, which is based on the frequency hopping method of the digital wireless communication device according to the present invention. It describes the wireless communication method. (A) shows the state of the input data converted into the symbol series by the data input circuit 1 on the transmission side. (B) shows a segment string cut out by the segment cutout circuit 2. (C) shows a segment string formed by adding the error detection code to each segment by the error detection code addition circuit 3. (D) is
A state in which one frame is formed by m (here, three) segments, and n (here, 20) frames are grouped together and repeatedly transmitted by the frame repeating circuit 5 twice. Indicates. And (e)
Shows a state in which the n frames are repeatedly transmitted on the wireless transmission path by the wireless transmission circuit 7 at different frequencies.

On the other hand, on the receiving side, the receiving antenna 100 →
Through the digital demodulation circuit 102 and the frame extraction circuit 103, n pieces of frame data that are repeated twice are taken out as shown in (f). Subsequently, the segment extraction circuit 105 extracts m pieces of segment data from each of the n pieces of frame data, and the effective segment determination circuit 1
The validity of the corresponding segment is determined at 06, and determination data is obtained as shown in (g). Then, as shown in (h), the data of the valid segment is output from the data output circuit 107.

FIG. 4 is a flow chart showing an example of the determination operation performed by the effective segment determination circuit 106 shown in FIG. The error of the received data of the segment extracted by the segment extraction circuit 105 is detected as follows. First, a parameter n indicating the number of frames to be transmitted as a group is initialized (n = 0) (S1). Then, the parameter m indicating the number of segments forming one frame is initialized (S2).

Next, error detection is performed for the m-th segment of the n-th frame f1n in the first frequency slot of repetition (S3).
If it is correct, the m-th segment information of the f1n frame is stored in the data buffer (S4),
Then, the process proceeds to step S8. If an error is detected in the error detection of step S3, the error detection is performed on the m-th segment of the n-th frame f2n in the second frequency slot of repetition (S5). ). If it is correct, f2n
The m-th segment information of the frame is stored in the data buffer (S6), and the process proceeds to step S8.

Furthermore, in step S5K, if an error is detected in the error detection, the nth frame f1n,
It is determined that the information of each m-th segment of f2n corresponding to this is incorrect (S7). While the parameter m is incremented (S8), error detection is continued for each segment until the number of segments reaches M (S9). The parameter n is also incremented (S10), and error detection is continued for each frame until the number of frames reaches N (S11).

In the above embodiment, on the receiving side,
In order to separate (extract) the frames that will be a group,
Although it was done by using the frequency hopping synchronization information, there are other methods such as checking the correlation of the data between the frames and embedding the identification information in the transmission frame on the transmitting side and then receiving it on the receiving side. It is also possible to adopt a method of referencing.

Specifically, in the case of the former method,
The correlation value between each reception frame and the reception frame preceding it is detected, and the result obtained by averaging the correlation value for each remainder divided by the number of repetitions of the frame number is smaller than a predetermined threshold value. Use as a delimiter for repeating frames. In the latter method, the transmitting side inserts the frame identification information into a predetermined position in the transmitting frame in advance, and the receiving side detects the frame identifying information to determine the delimiter of the repeated frame.

[0042]

As described above, according to the present invention, in transmitting a digital signal, when the transmission frequency is switched in a pseudo-random number, the burst error caused by the interference is dealt with and the data is interleaved. It is possible to realize a digital wireless communication device with extremely few transmission errors without increasing the delay time.

Therefore, when such a device is applied to a cordless telephone, generation of sidetone due to delay is avoided,
It is possible to secure good call quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a transmitting side of a digital wireless communication device according to the present invention.

FIG. 2 is a block diagram of a circuit configuration on the receiving side of the digital wireless device according to the present invention.

FIG. 3 is a schematic diagram showing each data configuration handled in a main circuit block of the digital wireless communication device shown in FIGS. 1 and 2.

FIG. 4 is a flowchart showing an example of a determination operation performed by an effective segment determination circuit 106 shown in FIG.

[Explanation of symbols]

 1 Data Input Circuit 2 Segment Extraction Circuit 3 Error Detection Code Addition Circuit 4 Frame Generation Circuit 5 Frame Repeating Circuit 6 Digital Modulation Circuit 7 Radio Transmission Circuit 8 Transmission Antenna 9 Transmission Side Hopping Control Circuit 10 Timing Circuit 100 Reception Antenna 101 Radio Reception Circuit 102 Digital demodulation circuit 103 Frame extraction circuit 104 Frame determination circuit 105 Segment extraction circuit 106 Effective segment determination circuit 107 Data output circuit 108 Reception side hopping control circuit 109 Synchronous circuit

Claims (6)

[Claims] 1. A frequency-hopping digital wireless communication device for transmitting a digital signal by switching a transmission frequency between a transmitting device and a receiving device in a pseudo-random number, wherein the transmitting device transmits a predetermined number of input data. Segment segmentation means for segmenting and segmenting into segments composed of symbols, error detection code addition means for adding an error detection code to each segment thus segmented, and a predetermined number of segments to which the error detection code is added. Frame generating means for generating one frame, frame repeating transmitting means for repeatedly transmitting a predetermined number of frames twice in synchronization with hopping timing, and digital modulating means for sequentially digitally modulating each transmitted frame , And wirelessly transmit each digitally modulated frame in order. A signal means, to said wireless transmission means, the center frequency of the transmitted carrier,
Transmission-side hopping control means for controlling to hop in a pseudo-random number, the segment cutout means, error detection code addition means,
The frame generation means, the frame repetitive transmission means, and the transmission-side hopping control means are provided with timing pulse providing means for applying timing pulses to each means so that they operate in synchronization with the hopping timing, and the receiving device communicates. Radio receiving means for receiving a radio signal from the opposite device, and reception side hopping control for controlling the radio receiving means so that the center frequency of each reception carrier wave is sequentially returned to the reference frequency in synchronization with the transmission side hopping timing. Means, digital demodulation means for converting the signal received by the wireless reception means into digital data, frame extraction means for extracting a predetermined number of frames from the demodulated data, and the extracted predetermined number of frames are repeated twice. Frame determination means for determining whether or not it is one, and each place repeated twice Segment extraction means for extracting a segment to which an error detection code is added from each of a fixed number of frames, segment determination means for determining whether or not the extracted segment is valid, and symbol synchronization from demodulated data. And frame synchronization, and the frame extraction means, the frame determination means, the segment extraction means, the segment determination means, and the reception side hopping control means operate timing in synchronization with each transmission side hopping timing. A digital wireless communication device comprising: a timing pulse providing means for applying a pulse. 2. The repeated frame sending operation by the repeated frame sending means in the transmitting device and the frame extracting operation by the frame extracting means in the receiving device cause generation of a hopping frequency sequence by the sending side hopping control means in the sending device. The digital wireless communication device according to claim 1, wherein the digital wireless communication device is interlocked. 3. The frame extracting means according to claim 1, wherein the frame extracting means determines a division of received data consisting of a predetermined number of frames based on the synchronization information from the timing pulse providing means. Digital wireless communication device. 4. The frame determining means according to claim 1, wherein the frame determining means determines a predetermined number of frames repeated twice based on the synchronization information from the timing pulse supplying means. Digital wireless communication device. 5. The segment determination means performs error detection using an added error detection code for the m-th segment in the n-th frame of each of a predetermined number of frames repeated twice, 5. The digital wireless communication device according to claim 1, wherein the validity of is determined. 6. The segment determining means, when no error is detected in both of the m-th segment in the corresponding n-th frame, outputs the data of the segment as valid, and the error is detected in both segments. 6. The digital wireless communication device according to claim 5, wherein, when is detected, the data of the segment is invalidated and an invalidation flag is output.