JP3243776B2 - Frequency hopping transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed frequency hopping transmission method for performing multiple access by dividing an information signal into small units in a mobile communication and frequency hopping over a wide band. In addition, the present invention particularly relates to demodulation of a receiving unit in a high-speed frequency hopping transmission method.

[0002]

2. Description of the Related Art CDMA transmission can be classified into a direct spreading (DS) system and a frequency hopping (FH) system in which a conventional modulated signal is spread by a high-rate spreading code. In the FH system, it is necessary to divide one symbol into units called chips and switch to a signal having a different center frequency for each chip at a high speed, and it is difficult to realize a device. Used. In the direct spreading method, each user performs communication in the same frequency band using different spreading codes, and each user is separated by detecting correlation of the spreading codes. In this case, the spreading code used for code division is not a perfect orthogonal code sequence but has a correlation between the sequences, causing interference between other stations performing simultaneous communication, and deteriorating communication quality.

[0003] On the other hand, in frequency hopping, data of each user is divided into chips corresponding to a spreading factor, and each chip is transmitted at a different carrier frequency. Therefore, in the downlink channel in the same cell, the signal of each user is completely separated on the frequency axis, and the orthogonality between channels is completely realized. FIG. 7 shows an operation principle in the case where high-speed frequency hopping is performed at a hopping frequency four times the information transmission rate. In this example, one information symbol is divided into four units called chips, and wirelessly propagates at different carrier frequencies f1 to f4. In this figure, the transmission pattern for one user is shown. However, since one user occupies one frequency at any one time in the three carrier frequency bands, four users can be shifted by time-shifting the transmission pattern. Communication can be performed without overlapping spectra on the frequency axis. One more information symbol is PG
When frequency hopping is performed by dividing into chips, PG users can communicate independently orthogonally to each other. In the uplink channel, when the propagation delay is considered, the synchronization at the chip level of each channel is not maintained, and the orthogonality of the channels becomes incomplete.

[0004] In frequency hopping, a frequency synthesizer capable of high-speed frequency switching is required as described above, and it is difficult to realize this. However, recently, DDS (Direct Digital
Synthesizer (LSI) LSIs have been manufactured, and switching at a much higher speed has become possible as compared with a conventional VCO (Voltage Control Oscilator) type frequency synthesizer. The Institute of Electronics, Information and Communication Engineers B-ll Vol.J77
B-ll No.5 pp.233-239 May 1993 "Configuration and Characteristics of High-Speed Frequency Hopping Transceiver Using Digital Signal Processing" enables high-speed frequency switching using ROM (Read Only Memory). A frequency hopping receiver capable of high-speed frequency switching using a frequency hopping modulator and a loopback signal by digital sampling has been proposed. In any case, the frequency hopping CDMA access system has been made possible by using the above-described frequency switching technology based on digital processing.

FIG. 6 shows a block diagram of a conventional receiver for performing high-speed frequency hopping. In FIG. 6, the frequency-hopped received signal is transmitted to a band-pass filter 60.
1 using the hopping frequency generated by the frequency hopping synthesizer 602.
To convert the signal back to a normal signal. This frequency hopping synthesizer 602 is the frequency synthesizer described above. Thereafter, the received signal subjected to the quadrature detection by the quadrature detection circuit 606 is converted into a digital signal by the A / D converter 607, and the delay detection circuit 608 and the identification / determination unit 60
9 is an information data output signal.

When the frequency hopping signal passes through the mobile communication channel, the received signal level and the received phase fluctuate due to Rayleigh fading. Therefore, in the conventional frequency hopping method, amplitude fluctuation and phase fluctuation caused by fading differ according to each carrier frequency. For this reason, in the phase modulation method in which information is propagated at the carrier wave phase, the information is identified by differentially encoding and placing the information on the relative phase of the preceding and succeeding symbols and performing delay detection on the receiving side as described above. Is generally determined. However, in this conventional receiving method using differential detection, since transmission data is differentially encoded as described above, a 1-bit error in a wireless section becomes a 2-bit error in information data. Therefore, as compared with the synchronous detection, for example, in the two-phase modulation scheme (BPSK modulation), the reception error rate deteriorates by about 3 dB for the same signal power to noise power ratio (SNR).

[0007]

SUMMARY OF THE INVENTION According to the present invention, in a high-speed frequency hopping transmission method for switching a carrier frequency over a wide band of information, a pilot symbol having a known transmission pattern is inserted into an information symbol section at a fixed period, and each carrier frequency is transmitted. The present invention provides a demodulation capable of performing absolute synchronous detection by estimating and compensating for a phase variation of a transmission line every time.

[0008]

According to the first aspect of the present invention,
In a frequency hopping transmission method in which information data is divided into N and each of the N divided data (chips) is transmitted at a different carrier frequency to perform multiple access transmission, a transmitting side transmits a pilot signal having a known pattern between information data signals. Pilot symbol periodically inserted every few symbols
Generate and transmit a frame configuration having a vol section , the receiving side frequency-converts the input signal into a signal having a center frequency of zero according to the hopping pattern, and in the pilot symbol section, obtains the phase of each chip, the calculated error by averaging with pyro <br/> Tsu preparative symbol interval, in the information symbol section, in accordance with the information symbol section position the amplitude and phase of the chip at the same carrier frequency in each symbol, obtained error And compensating by interpolating, and synthesizing the signals of the chips in one symbol that have been phase-compensated in phase, and identifying and determining the synthesized signal.

According to a second aspect of the present invention, in a frequency hopping transmission system for performing multiple access transmission by dividing information data into N and transmitting the N-divided data (chips) at different carrier frequencies, the transmitting side includes: It has a pilot symbol section in which a pilot signal with a known pattern is periodically inserted every few symbols between information data signals.
Generate and transmit a frame configuration that the reception side, a frequency conversion section for frequency-converting the center frequency of zero signal input signal in accordance with the hopping pattern, in the pilot symbol interval, the phase of each chip determined, a pilot symbol phase error extracting unit for obtaining an error by averaging in the Pas <br/> pilots symbols interval, the information symbol period, amplitude and phase information symbols in the chip at the same carrier frequency in each symbol A data / symbol phase compensator for interpolating and compensating for the obtained error according to the section position, a chip in-phase synthesizer for synthesizing in-phase the signals of the respective chips in one symbol whose phase is compensated, A frequency hopping transmission system including an identification / determination unit that identifies and determines a synthesized signal.

According to a third aspect of the present invention, there is provided a receiving apparatus in a frequency hopping transmission system for performing multiple access transmission by dividing information data into N and transmitting the N-divided data (chips) at different carrier frequencies. A frequency conversion unit for converting the frequency of an input signal into a signal having a center frequency of zero according to a pattern;
The pilot signal is cycled every few symbols between information data signals.
In the pilot symbol section inserted periodically ,
Obtains a phase of each chip, a pilot symbol phase error extracting unit for obtaining an error by averaging in the pilot symbol interval, in the information symbol section, the amplitude and phase of the information symbol in the chip at the same carrier frequency in each symbol A data / symbol phase compensator for interpolating and compensating for the obtained error according to the section position, a chip in-phase synthesizer for synthesizing in-phase the signals of the respective chips in one symbol whose phase has been compensated, A receiving apparatus in a frequency hopping transmission system, comprising: an identification / determination unit that identifies and determines a synthesized signal.

According to a fourth aspect of the present invention, the frequency conversion section performs frequency conversion on an analog reception signal, and then converts the signal into a digital signal by an A / D conversion section. 3. A receiving device in the frequency hopping transmission system according to 3.

According to a fifth aspect of the present invention, the frequency conversion section performs frequency conversion on a digital reception signal converted into a digital signal by an A / D conversion section. It is a receiving device in a frequency hopping transmission system.

[0013]

According to the present invention, in a high-speed frequency hopping transmission method for switching a carrier frequency over a wide band of information, a pilot symbol having a known transmission pattern is inserted into an information symbol section at a constant period. Absolute synchronous detection can be realized by estimating and compensating for phase fluctuations of the transmission line for each carrier frequency using the pilot symbols. Compared to the conventional method using differential detection,
The received signal power for obtaining the same reception error rate characteristic is almost 3
It can be reduced by about dB. This means that the transmission power can be reduced by about 3 dB.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of a basic configuration of a high-speed frequency hopping signal receiving apparatus according to the present invention. For each chip signal in one received information symbol, a local frequency of a carrier frequency (or an offset frequency) corresponding to each carrier frequency generated by the hopping pattern generator 105 is digitally output by the local frequency generator 104. Generate as a signal. This frequency and a received digital signal obtained by A / D conversion of the received signal are subjected to complex multiplication by the frequency converter 103 to generate a baseband signal having a center frequency of zero. At this point, the received complex baseband signal undergoes phase rotation because it undergoes independent transmission path fluctuations at each carrier frequency. In order to perform absolute synchronous detection on the phase modulation signal, it is necessary to determine the absolute phase of the reception phase. In the frequency hopping transmission method according to the present invention, a method of periodically inserting a pilot signal having a known transmission pattern of several symbols into an information signal is used.

FIG. 2 shows a frame configuration according to the present invention. FIG. 2 shows a pilot symbol and a data symbol.
And each symbol is represented by 4 blocks.
An example in the case of dividing into one chip and performing fast frequency hopping will be described. Using the known pilot symbols included in the frame, the absolute phase at the receiving side in the same transmission path can be obtained from the received phase. In a mobile communication environment, it is necessary to insert pilot symbols at intervals where transmission path fluctuations due to Rayleigh fluctuations can be ignored. A description will be given below assuming that a transmission signal including such a pilot symbol is received.

In FIG. 1, pilot symbol phase error detecting section 108 obtains the absolute phase on the receiving side at each carrier frequency using the pilot symbols. This processing is equivalent to obtaining a phase error with respect to the transmission phase. Pilot symbols contiguous several symbols in one block (hereinafter, the pilot symbol section
) To eliminate the effect of thermal noise. Estimation of the received phase of the information data, those
Obtained by interpolating the received phase errors of the pilot symbol interval and the next block <br/> pilot symbol section of the block, and a reception phase error at each of the information symbol positions, the data symbol phase compensator 106 By correcting this phase error, the absolute reception phase of each information data is obtained.

FIG. 5 shows a data symbol phase compensator 10.
6 shows the principle of a method for obtaining the reception phase of each information symbol in each chip using pilot symbols. FIG. 5 shows a case where straight line correction is performed. Within one block using the received known pilot symbols
The phase error is corrected by linearly interpolating the pilot symbol section of

In FIG. 1, since the information data is the same in each chip within one symbol, the chip in-phase synthesizing circuit 109 in-phase synthesizes the signals of the respective chips on the complex plane. A signal obtained by combining the signals of all chips in one symbol is identified / determined by the identification / determination circuit 110 into data of 1 or 0.

[0020] In this configuration, the pilot symbol interval, obtains the phase of each chip, the pilot Shi
The error is obtained by averaging over the symbol interval. Using this error, in the information symbol section, the amplitude and phase of the chip at the same carrier frequency in each symbol are compensated by interpolation according to the information symbol section position. Since the fading distortion is compensated in this way, absolute synchronous detection can be performed.

FIG. 3 is a block diagram showing a detailed embodiment of the high-speed frequency hopping apparatus according to the present invention. Receiver input R
After the band-pass filter (BPF) 303, the F frequency is mixed with a signal from the local oscillator 305 by the frequency conversion unit 304, and frequency-converted to IF (intermediate frequency). At this point, the AGC is performed while the center frequency of each chip is different.
The signal is amplified by the amplifier 307 to a required signal level. Thereafter, the quadrature detection circuit 308 outputs the baseband in-phase component and the quadrature component, and the A / D converter 309 converts the components into digital signals. The digital signal is
The digital processing frequency conversion unit 310 uses the frequency generated by the local frequency generation unit 311 in accordance with the hopping pattern from the hopping pattern unit 312,
The frequency is converted to a signal having a center frequency of zero. This is a signal that has not been subjected to normal frequency hopping. The frequency-converted chips are subjected to transmission path estimation using a pilot symbol for each chip in a pilot symbol phase error extracting section 313 and a phase error averaging / estimating section 314, and are phase compensated. In particular,
Pilot symbol phase error extracting unit 313, the phase error averaging-estimator 314, a pilot symbol interval, obtains the phase of each chip, the pilot Singh
The phase error is obtained by averaging in the vol interval. And
Using the obtained phase error, for the delayed information symbol, the amplitude and phase of the chip at the same carrier frequency in each symbol are obtained by interpolation according to the information symbol position, and the data symbol phase compensation is performed. In the section 316, the phase is corrected. The compensated signal is output to the chip in-phase synthesis circuit 320.
, The chip data in one symbol are combined in phase. Thereafter, the combined data symbol is returned to information data by the identification / determination circuit 321 and output.

The frequency conversion unit 310, the local frequency generation unit 311, and the frequency conversion unit configured to perform the frequency conversion in the baseband.
Specific examples of the hopping pattern generator include: (1) ROM, DDS (Direct Digital Synthesizer)
A method of performing complex multiplication processing or equivalent processing on the digital frequency waveform generated by the above method.

(2) A method of performing frequency-time conversion using fast Fourier transform (FFT).

(3) There is a method using a frequency conversion filter using a loopback signal by sampling, which is described in the literature of the related art.

FIG. 4 shows an embodiment of a high-speed frequency hopping signal receiving apparatus for performing high-speed frequency conversion in an analog manner in the RF band or the IF band. In this case, a frequency synthesizer 405 capable of high-speed frequency switching is required. The processing after the A / D converter 410 is the same as in the embodiment of FIG. Therefore, the description is omitted.

Further, by using a pilot symbol signal in a frame used in the present invention to detect a frequency hopping pattern in one symbol in a plurality of pilot symbol sections, to perform initial synchronization and tracking. Can also.

[0027]

As described above, according to the present invention, in a high-speed frequency hopping transmission method for switching information over a wide frequency band, a pilot symbol having a known transmission pattern is inserted into an information symbol section at a constant period. Absolute synchronous detection can be realized by estimating and compensating for phase fluctuations of the transmission line for each carrier frequency using the pilot symbols. Compared with the conventional method using differential detection, the received signal power for obtaining the same reception error rate characteristic can be reduced by about 3 dB. this is,
In other words, it means that the transmission power can be reduced by about 3 dB.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a basic configuration of a receiving device of a high-speed frequency hopping transmission system according to the present invention.

FIG. 2 is a block diagram illustrating a frame configuration of a high-speed frequency hopping signal according to the present invention.

FIG. 3 is a block diagram illustrating a detailed configuration of a receiving apparatus of the high-speed frequency hopping transmission system according to the present invention.

FIG. 4 is a block diagram showing the configuration of another embodiment of the high-speed frequency hopping transmission system of the present invention.

FIG. 5 is a diagram illustrating a principle of obtaining a reception phase of each chip in the high-speed frequency hopping transmission system of the present invention.

FIG. 6 is a diagram illustrating a block configuration of a receiver of a conventional frequency hopping transmission system.

FIG. 7 is a diagram illustrating the principle of fast frequency hopping.

[Explanation of symbols]

 Reference Signs List 101 Spread signal input terminal 102 Identification judgment data output terminal 103 Frequency conversion unit 103 Local frequency generation unit 105 Hopping pattern generator 106 Pilot symbol phase error extraction and averaging unit 107 Data symbol delay unit 108 Data symbol phase compensation unit 109 Chip in-phase synthesis circuit 110 Identification / judgment unit 301 RF modulation signal input terminal 302 Identification judgment data output terminal 303 BPF (bandpass filter) 303 Mixer 305 Oscillator 306 BPF (Bandpass filter) 307 AGC amplifier 308 Quadrature detector 309 A / D converter 310 Frequency conversion unit 311 Local frequency generation unit 312 Hopping pattern generation unit 313 Pilot symbol phase error extraction unit 314 Pilot symbol phase error averaging unit 315 Data / symbol delay section 316 Data / symbol phase compensating section 317 Symbol / timing extracting section 318 Frame / timing extracting section 319 Memory circuit 320 Chip in-phase combining circuit 321 Identification / determination section 401 RF modulation signal input terminal 402 Identification determination data output terminal 403 BPF (Band Pass Filter) 403 Mixer 405 Hopping Synthesizer 406 Hopping Pattern Generator 407 BPF (Band Pass Filter) 408 AGC Amplifier 409 Quadrature Detector 410 A / D Converter 410 Frequency Converter 411 Pilot Symbol Phase Error Extraction unit 412 Pilot symbol phase error averaging unit 413 Data symbol delay unit 414 Data symbol phase compensation unit 415 Symbol timing extraction unit 416 Frame Timing extraction unit 417 Memory circuit 418 Chip in-phase synthesis circuit 419 Identification / judgment unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H04B 1/69-1/713 H04J 13/00-13/06

Claims (5)

(57) [Claims] 1. A frequency hopping transmission method in which information data is divided into N, and each of the N divided data (chips) is transmitted at a different carrier frequency to perform multiple access transmission. Pilot periodically inserted every few symbols between information data signals
Generating and transmitting a frame configuration having a symbol section , the receiving side converts the frequency of the input signal into a signal having a center frequency of zero according to the hopping pattern, and obtains the phase of each chip in the pilot symbol section. obtains an error by averaging in the pilot symbol interval, in the information symbol section, the amplitude and phase of the chip at the same carrier frequency in each symbol in accordance with the information symbol interval position, said interpolation by error obtained A frequency hopping transmission method comprising: synthesizing the signals of each chip in one symbol, the phases of which are compensated in phase, and identifying and determining the synthesized signals. 2. In a frequency hopping transmission system in which information data is divided into N and each of the N divided data (chips) is transmitted at a different carrier frequency to perform multiple access transmission, a transmitting side transmits a pilot signal having a known pattern. Pilot periodically inserted every few symbols between information data signals
- generate and transmit a frame structure having a symbol interval, the receiver, a frequency converter for frequency-converting the center frequency of zero signal input signal in accordance with the hopping pattern, in the pilot symbol interval, each chip seeking phase, the pilot symbol phase error extracting unit for obtaining an error by averaging in the pilot symbol interval, the information symbol period, the information symbol section position the amplitude and phase of the chip at the same carrier frequency in each symbol A data / symbol phase compensator for interpolating and compensating for the obtained error, a chip in-phase synthesizer for synthesizing the phase-compensated signal of each chip in one symbol in phase, A frequency hopping transmission system comprising an identification / determination unit for identifying and determining a signal. 3. A receiving apparatus in a frequency hopping transmission system for dividing information data into N and transmitting each of the N-divided data (chips) at a different carrier frequency to perform multiple access transmission. And a frequency conversion unit that converts the frequency to a signal with a center frequency of zero, and a pilot signal with a known pattern between the information data signal.
In periodically inserted pilot symbol interval is every few symbols, and each chip obtains a phase of the pilot <br/> averages with preparative symbol period pilot symbol phase error extracting unit for obtaining the error information In the symbol section, a data / symbol phase compensator for interpolating and compensating for the amplitude and phase of the chip at the same carrier frequency in each symbol according to the information symbol section position according to the position of the information symbol section. A receiving apparatus in a frequency hopping transmission system, comprising: a chip in-phase combining unit that combines signals of respective chips in one symbol in phase with each other; and an identification / determination unit that identifies and determines the combined signal. 4. The frequency hopping transmission according to claim 3, wherein the frequency conversion unit performs frequency conversion on an analog reception signal, and thereafter converts the received signal into a digital signal by an A / D conversion unit. Receiving device in the system. 5. The reception in the frequency hopping transmission system according to claim 3, wherein the frequency conversion section performs frequency conversion on a digital reception signal converted into a digital signal by an A / D conversion section. apparatus.