JP2010239272A - Ofdm transmitting apparatus, ofdm receiving apparatus, ofdm transmission system, and ofdm communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a transmission rate even if a propagation environment cannot be significantly improved to change a modulation method. <P>SOLUTION: An encoder 101 encodes input data, outputs some of encoded data to an S/P unit 102 and outputs the other encoded data to a phase modulator 104. The S/P unit 102 performs serial/parallel conversion on a data stream output from the encoder 101. Each of primary modulators 103-1 to 103-n modulates the data stream output from the S/P unit 102 to produce a symbol. The phase modulator 104 rotates the phase of symbols output from the primary modulators 103-1 to 103-n from the phase of a preceding symbol just by a shift amount based on the encoded data output from the encoder 101. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an OFDM transmitter, an OFDM receiver, an OFDM transmission system, and an OFDM communication method that perform OFDM (Orthogonal Frequency Division Multiplexing) communication using a multicarrier modulation signal.

  In recent years, in wireless communication, particularly mobile communication, various information such as images and data other than voice has been the object of transmission. In the future, the need for higher-speed transmission is expected to increase further, and in order to perform high-speed transmission, wireless transmission technology that achieves high transmission efficiency by using limited frequency resources more efficiently is required. It has been.

  One such wireless transmission technique is the OFDM (Orthogonal Frequency Division Multiplexing) transmission system. The OFDM transmission system has features such as high frequency utilization efficiency and reduction of inter-symbol interference in a multipath environment, and is known to be effective in improving transmission efficiency (Patent Document 1).

  A transmitter used in an OFDM transmission system (hereinafter referred to as an “OFDM transmitter”) modulates data using a modulation method such as QPSK (Quadrature Phase Shift Keying) or QAM (Quadrature Amplitude Modulation). Then, a symbol is generated, and the symbol is superimposed on a plurality of orthogonal subcarriers (subcarriers) to generate an OFDM symbol.

  Further, the OFDM transmitter adds a guard interval obtained by circulating a part of the effective symbol waveform to the OFDM symbol, converts the OFDM symbol to a radio frequency, and transmits the radio signal from the antenna. By adding a guard interval, it is possible to reduce degradation of reception quality due to multipath.

  In the field of wireless communication, it is desired to further improve the transmission rate while maintaining a predetermined reception quality (error rate). In the conventional OFDM transmission system, when the propagation environment (line quality) is good, the transmission rate is improved by increasing the number of modulation levels per symbol.

FIG. 10 is a diagram illustrating a relationship between an SNR (Signal to Noise Ratio) (horizontal axis) that is an index representing a propagation environment and a BER (Bit Error Rate) (vertical axis) that is an index representing reception quality. As shown in FIG. 10, there is a correlation between SNR and BER. In addition, a target SNR for obtaining a predetermined reception quality T _BER is determined for each modulation scheme, and the modulation scheme having a larger modulation multi-level number has a higher target SNR. For example, in FIG. 10, the target SNR if the modulation scheme is a QPSK (modulation order m = 2) is _{A 1,} the modulation scheme is the target SNR = _{A 2} as long as 16QAM (m = 4).

In a conventional OFDM transmission system, a SNR is periodically measured at a receiving apparatus (hereinafter referred to as “OFDM receiving apparatus”), and a measurement result is notified to the OFDM transmitting apparatus. The OFDM transmitting apparatus has a SNR exceeding A ₂ In addition, the modulation scheme is changed from QPSK to 16QAM, and OFDM symbols are transmitted to improve the transmission rate.
JP 2001-77789 A

  However, in the conventional method, since the interval of the target SNR of each modulation method is large, the propagation environment must be significantly improved until a predetermined reception quality can be obtained in a modulation method having a larger modulation multi-level number than the present method. The modulation method cannot be changed.

For example, in FIG. 10, when the SNR is A ₃ between A ₁ and A ₂ , the modulation scheme is changed from QPSK to 16 QAM even though the propagation environment is better than when the SNR is A _1. If it is changed, the predetermined reception quality T _BER cannot be obtained, so that the modulation method cannot be changed and the transmission rate cannot be improved.

  The present invention has been made in view of the above points, and an OFDM transmission apparatus and OFDM capable of improving the transmission rate even when the degree of improvement of the propagation environment is small enough not to change the modulation method. It is an object to provide a receiving apparatus, an OFDM transmission system, and an OFDM communication method.

  An OFDM transmission apparatus according to the present invention is an OFDM transmission apparatus that processes data by an OFDM transmission method and wirelessly transmits the obtained signal, and an encoding means for encoding input data; First encoded data that is a part of the encoded data is modulated for each subcarrier to generate a symbol, and second encoded data that is the remaining data encoded by the encoding means It adopts a configuration comprising phase modulation means for rotating the phase of the symbol generated by the primary modulation means from the immediately preceding symbol by the shift amount.

  An OFDM receiving apparatus of the present invention is an OFDM receiving apparatus that processes a radio signal transmitted from the OFDM transmitting apparatus and extracts data, and a phase difference between a symbol obtained from the received signal and a symbol immediately preceding it. And a phase correction that reversely rotates the phase of the symbol obtained from the received signal by a shift amount represented by the second encoded data extracted by the delay detection unit. Means, primary demodulation means for demodulating the symbol whose phase is reversed by the phase correction means to extract the first encoded data, and the first encoded data and the delay detection means extracted by the primary demodulation means And a decoding means for decoding the second encoded data taken out.

  An OFDM transmission system according to the present invention is an OFDM transmission apparatus that processes data by an OFDM transmission method and wirelessly transmits the obtained signal, and an OFDM reception apparatus that processes a wireless signal transmitted from the OFDM transmission apparatus and extracts data The OFDM transmitter includes: an encoding unit that encodes input data; and a first encoded data that is a part of the data encoded by the encoding unit. The phase of the symbol generated by the primary modulation means is equal to the amount of shift indicated by the primary modulation means for modulating each carrier to generate a symbol and the second encoded data that is the remaining data encoded by the encoding means. And a phase modulation means for rotating from the immediately preceding symbol, wherein the OFDM receiving apparatus includes a symbol obtained from the received signal, and the immediately preceding symbol. The phase of the symbol obtained from the received signal by the amount of shift represented by the second encoded data extracted by the delay detection means and the delay detection means for extracting the second encoded data from the phase difference from the symbol. Phase correcting means for reversely rotating, primary demodulating means for demodulating a symbol whose phase has been reversely rotated by the phase correcting means to extract the first encoded data, and the first encoded data extracted by the primary demodulating means And a decoding means for decoding the second encoded data taken out by the delay detection means.

  The OFDM communication method of the present invention processes data in an OFDM transmission device, wirelessly transmits the obtained signal, and processes the wireless signal transmitted from the OFDM transmission device in an OFDM reception device, and extracts data. In the OFDM communication method, an encoding process for encoding input data and first encoded data, which is a part of data encoded in the encoding process, is modulated for each subcarrier in the OFDM transmitter. Then, the phase of the symbol generated in the primary modulation step by the amount of shift represented by the second encoded data that is the remaining data encoded in the encoding step and the primary modulation step for generating the symbol is changed to the immediately preceding symbol. And a phase modulation step of rotating from the symbol received from the received signal in the OFDM receiver, and the symbol immediately before The phase of the symbol obtained from the received signal is reversely rotated by a delay detection step for extracting the second encoded data from the phase difference, and a shift amount represented by the second encoded data extracted in the delay detection step. A phase correction step, a primary demodulation step of demodulating a symbol whose phase has been reversely rotated in the phase correction step and extracting the first encoded data, and the first encoded data and the delay extracted in the primary demodulation step A decoding step of decoding the second encoded data taken out in the detection step.

  According to the present invention, a part of the encoded data is allocated for phase modulation, and the degree of improvement of the propagation environment is modulated by phase modulating the primary modulated data based on the allocated data. The transmission rate can be improved even if the system is not narrow enough to change the system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
1.1 Configuration of OFDM Transmitting Device FIG. 1 is a block diagram showing a configuration of an OFDM transmitting device according to Embodiment 1 of the present invention. 1 includes an encoding unit 101, an S / P (serial / parallel conversion) unit 102, primary modulation units 103-1 to 103-n, a phase modulation unit 104, and an IFFT unit 105. And a P / S (parallel / serial conversion) unit 106, a GI (guard interval) adding unit 107, a transmission RF unit 108, and a transmission antenna 109.

  Encoding section 101 adds an error detection code to the input data, performs error correction encoding processing, and outputs the encoded data to S / P section 102 or phase modulation section 104. The encoding unit 101 repeats outputting k-bit data to the phase modulation unit 104 after outputting m × n-bit data to the S / P unit 102. Here, m is the modulation multi-level number, n is the number of subcarriers, and k is the number of bits of data representing the phase difference between two consecutive symbols.

  The S / P unit 102 converts the data sequence output in series from the encoding unit 101 into n parallel data sequences (serial / parallel processing), and converts the data sequences to primary modulation units 103-1 to 103, respectively. Output to -n.

  Each primary modulation section 103-1 to 103-n modulates QPSK (m = 2), 16QAM (m = 4) or the like in units of m bits with respect to the data string output from the S / P section 102. A symbol is generated by performing modulation processing according to the method, and is output to the phase modulation unit 104.

  The phase modulation unit 104 inserts a symbol (for example, a pilot symbol) that is known by the OFDM receiver to the symbols output from the primary modulation units 103-1 to 103-n. Then, the phase modulation unit 104 rotates the phase of the symbol into which the known symbol is inserted from the phase of the previous symbol by the shift amount based on the k-bit data output from the encoding unit 101 (phase modulation processing). And output to the IFFT unit 105. By performing the phase modulation process, information can be put on the phase difference from the immediately preceding symbol.

  The IFFT unit 105 performs an inverse Fourier transform (IFFT) process on the symbol output from the phase modulation unit 104 to generate an OFDM symbol superimposed on n subcarriers having different frequencies, and this OFDM symbol The symbol is output to the P / S unit 106.

  P / S section 106 multiplexes n OFDM symbols output from IFFT section 105 (parallel / serial conversion processing), and outputs the result to GI adding section 107.

  GI adding section 107 adds a guard interval obtained by circulating a part of the effective symbol waveform to the OFDM symbol output from P / S section 106 (GI adding process), and outputs the result to transmission RF section 108.

  The transmission RF unit 108 performs predetermined radio processing such as amplifier conversion on the OFDM symbol that is a baseband signal output from the GI addition unit 107, and transmits a radio frequency signal from the transmission antenna 109 to the OFDM receiver. Wirelessly transmit.

  Next, an OFDM receiver that receives an OFDM symbol wirelessly transmitted from the OFDM transmitter shown in FIG. 1 will be described with reference to FIG.

1.2 Configuration of OFDM Receiver FIG. 2 is a block diagram showing a configuration of the OFDM receiver according to the present embodiment. 2 includes a reception antenna 201, a reception RF unit 202, a synchronous detection unit 203, a GI (guard interval) removal unit 204, an S / P (serial / parallel conversion) unit 205, FFT unit 206, delay detection unit 207, buffer 208, phase correction unit 209, primary demodulation units 210-1 to 210-n, P / S (parallel / serial conversion) unit 211, decoding unit 212, , Mainly composed of.

  The reception RF unit 202 performs predetermined radio processing such as down-conversion on the radio frequency signal received by the reception antenna 201, and outputs an OFDM symbol, which is a baseband signal, to the synchronous detection unit 203.

  The synchronous detection unit 203 detects a leading portion of the OFDM symbol output from the reception RF unit 202 using a known symbol (synchronous detection processing), and outputs the OFDM symbol to the GI removal unit 204 at a predetermined timing.

  GI removal section 204 removes the guard interval from the OFDM symbol output from synchronous detection section 203 (GI removal processing), and outputs the result to S / P section 205.

  S / P section 205 separates the OFDM symbol output from GI removal section 204 into n OFDM symbols having different frequencies (serial / parallel conversion processing), and outputs the result to FFT section 206.

  The FFT unit 206 performs an FFT (Fourier transform) process on the OFDM symbol output from the S / P unit 205 to extract symbols superimposed on each subcarrier, and the symbol sequence is sent to the delay detection unit 207. Output.

  The delay detection unit 207 detects a phase difference between the known symbol part of the symbol output from the FFT unit 206 and the known symbol part of the immediately preceding symbol stored in the buffer 208 (delay detection process), and represents the phase difference. The k-bit data is output to the phase correction unit 209 and the decoding unit 212. Further, the delay detection unit 207 performs the delay detection process, and then outputs the symbols output from the FFT unit 206 to the buffer 208 and the phase correction unit 209 as they are.

  The buffer 208 temporarily stores the symbol output from the delay detection unit 207. Note that the buffer 208 erases the already stored symbols when a new symbol is input. Further, the buffer 208 outputs the stored symbol to the delay detection unit 207 at the timing when the delay detection unit 207 starts the delay detection process.

  The phase correction unit 209 performs a process (phase correction process) for reversely rotating the phase of the symbol output from the delay detection unit 207 by the shift amount based on the data indicating the phase difference output from the delay detection unit 207. The symbols from which the symbol portions have been removed are output to primary demodulation sections 210-1 to 210-n.

  The primary demodulation units 210-1 to 210-n perform demodulation processing on the symbols output from the phase correction unit 209, extract data, and output the data to the P / S unit 211.

  The P / S unit 211 converts n pieces of data output from the primary demodulation units 210-1 to 210-n in series (parallel / serial conversion processing), and outputs the data to the decoding unit 212.

  The decoding unit 212 performs error correction decoding processing and error detection processing on the data output from the P / S unit 211, and time-multiplexes the data output from the delay detection unit 207 to output final data. .

1.3 Specific Explanation of Phase Modulation Processing and Delay Detection Processing Next, the phase modulation processing in the phase modulation unit 104 shown in FIG. 1 and the delay detection processing in the delay detection unit 207 shown in FIG. And it demonstrates concretely using FIG. FIG. 3 is a diagram showing a constellation of symbols subjected to phase modulation processing, and FIG. 4 is a diagram showing a constellation of symbols subjected to delay detection processing. 3 and 4 show symbol constellations from time t1 to time t4.

  3 and 4 show the case where QPSK is used as the primary modulation method and DQPSK (Differential Quadrature Phase Shift Keying) is used as the phase modulation method. DQPSK is one of digital signal modulation methods, and is a method of assigning 2-bit data to each of the four modulated phases and giving information using the phase difference from the immediately preceding data.

1.3.1 Processing for First Symbol (Time t1) The first symbol at time t1 obtained by modulating data in each primary modulation section 103-1 to 103-n is a symbol position 311 on the constellation. To 314. For example, a symbol obtained by modulating (0, 0) data is arranged at the symbol position 311. Phase modulation section 104 sets the phase of the pilot symbol inserted into the first symbol to 0 ° (symbol position 310 in FIG. 3).

  Since the phase (0 °) of the pilot symbol included in the first symbol is known, the delay detection unit 207 can calculate the amount by which the phase of the first symbol is rotated in the radio section. In the example of FIG. 3, since the phase of the pilot symbol position 410 included in the received first symbol is 270 °, the first symbol (any one of the symbol positions 411 to 414 in FIG. 4) is 270 in the radio section. You can see that it rotates. By returning the rotation in this radio section to the original state in the phase correction unit 209, the primary demodulation unit 210 can correctly demodulate data from the first symbol.

1.3.2 Processing for Second Symbol (Time t2) Next, the phase modulation unit 104 sets the phase of the second symbol at the time t2 to the first by the shift amount based on the data output from the encoding unit 101. Rotate with respect to the symbol (any of symbol positions 321 to 324 in FIG. 3). Similarly, phase modulation section 104 rotates the phase of the pilot symbol inserted into the second symbol by the amount of shift based on the data output from encoding section 101 with respect to the pilot symbol inserted into the first symbol ( Symbol position 320 in FIG. In the example of FIG. 3, the data output from the encoding unit 101 is (0, 0). In this case, the phase modulation unit 104 rotates the second symbol including the pilot symbol by 45 °.

  The delay detection unit 207 detects the phase difference between the received second symbol and the pilot symbol included in the first symbol, thereby estimating the shift amount by which the phase modulation unit 104 has rotated the phase of the second symbol. In the example of FIG. 3, since the phase of the pilot symbol position 420 included in the received second symbol is 315 °, the delay detector 207 has a phase difference of 45 ° between the second symbol and the first symbol. Thus, it can be estimated that the data output from the encoding unit 101 is (0, 0). Since the phase of pilot symbol position 420 included in the received second symbol is 315 °, second symbol (any of symbol positions 421 to 424 in FIG. 4) is rotated by 45 ° in phase modulation section 104. Furthermore, it can be seen that the wireless section rotates 270 °. In the phase correction unit 209, the rotation by the phase modulation unit 104 and the rotation in the wireless section are restored to the original, so that the primary demodulation unit 210 can correctly demodulate data from the second symbol.

1.3.3 Processing for Third Symbol (Time t3) Next, the phase modulation section 104 changes the phase of the third symbol at the time t3 to the second amount by the shift amount based on the data output from the encoding section 101. Rotate with respect to the symbol (any of symbol positions 331 to 334 in FIG. 3). Similarly, phase modulation section 104 rotates the phase of the pilot symbol inserted into the third symbol by the amount of shift based on the data output from encoding section 101 with respect to the pilot symbol inserted into the second symbol ( Symbol position 330 in FIG. In the example of FIG. 3, the data output from the encoding unit 101 is (0, 1). In this case, the phase modulation unit 104 changes the third symbol including the pilot symbol to 135 ° from the second symbol. Rotate.

  The delay detection unit 207 detects the phase difference between the received third symbol and the pilot symbol included in the second symbol, thereby estimating the shift amount by which the phase modulation unit 104 has rotated the phase of the third symbol. In the example of FIG. 3, since the phase of the pilot symbol position 430 included in the received third symbol is 90 °, the delay detection unit 207 has a phase difference of 135 ° between the third symbol and the second symbol. It can be estimated that the data output from the encoding unit 101 is (0, 1). Since the phase of the pilot symbol position 430 included in the received third symbol is 90 °, the third symbol (any one of the symbol positions 431 to 434 in FIG. 4) is 180 ° ( 45.degree. + 135.degree.) And further 270.degree. In the wireless section. In the phase correction unit 209, the rotation by the phase modulation unit 104 and the rotation in the wireless section are restored to the original, so that the primary demodulation unit 210 can correctly demodulate data from the third symbol.

1.3.4 Processing for Fourth Symbol (Time t4) Next, the phase modulation unit 104 changes the phase of the fourth symbol at the time t4 by the amount of shift based on the data output from the encoding unit 101, to the third symbol. Rotate with respect to the symbol (any of symbol positions 341 to 344 in FIG. 3). Similarly, phase modulation section 104 rotates the phase of the pilot symbol inserted into the fourth symbol by the amount of shift based on the data output from encoding section 101 with respect to the pilot symbol inserted into the third symbol ( Symbol position 340 in FIG. In the example of FIG. 3, the data output from the encoding unit 101 is (0, 0). In this case, the phase modulation unit 104 changes the fourth symbol including the pilot symbol to 45 ° from the third symbol. Rotate.

  The delay detection unit 207 detects the phase difference between the received fourth symbol and the pilot symbol included in the third symbol, thereby estimating the shift amount by which the phase modulation unit 104 has rotated the phase of the fourth symbol. In the example of FIG. 3, since the phase of the pilot symbol position 440 included in the received fourth symbol is 135 °, the delay detection unit 207 has a phase difference of 45 ° between the fourth symbol and the third symbol. Thus, it can be estimated that the data output from the encoding unit 101 is (0, 0). Since the phase of the pilot symbol position 440 included in the received fourth symbol is 135 °, the fourth symbol (any one of the symbol positions 441 to 444 in FIG. 4) is 225 ° ( 45 ° + 135 ° + 45 °), and further 270 ° in the wireless section. In the phase correction unit 209, the rotation by the phase modulation unit 104 and the rotation in the wireless section are restored to the original, so that the primary demodulation unit 210 can correctly demodulate data from the fourth symbol.

1.4 Specific Description of Transmission Rate Improvement Effect According to this Embodiment Next, the transmission rate improvement effect according to this embodiment will be specifically described. As an example, when the primary modulation scheme is QPSK (modulation multilevel number m = 2), the subcarrier number n is 48, and the phase modulation scheme is DQPSK (k = 2), each subcarrier has s = 100 symbols. The prior art and this embodiment are compared with respect to the number of bits of data that can be transmitted at the time of transmission.

  In the above case, the number of bits of data that can be transmitted by the conventional technique is n × m × s = 48 × 2 × 100 = 9600 bits.

  On the other hand, in the above case, the number of bits of data that can be transmitted in the present embodiment is n × m × s + k × (s−1) = 48 × 2 × 100 + 2 × (100−1) = 9798 bits, According to the present embodiment, it is possible to increase the number of bits of data that can be transmitted per unit time (increase the transmission rate) compared to the prior art.

1.5 Effects of the Embodiment As described above, according to the present embodiment, a part of the encoded data is allocated for phase modulation, and the primary modulated data is based on the allocated data. By performing phase modulation, the transmission rate can be improved even if the degree of improvement in the propagation environment is small enough not to change the modulation method.

  Further, in the present embodiment, by assigning redundant bits such as turbo code parity bits as phase modulation data, the number of bits of data that can be transmitted with respect to the prior art is increased, Since more redundant bits can be transmitted than in the prior art, it is possible to improve the error correction capability.

  Although FIG. 1 shows the case where the phase modulation process is performed after the primary modulation process, in this embodiment, the phase modulation process is performed after the GI addition process as shown in FIG. However, the same effect can be obtained.

  In this embodiment, as shown in FIGS. 6 and 7, two encoding units 101-1 and 101-2 and two decoding units 212-1 and 212-2 are prepared, and two types of channels are prepared. May be individually encoded and decoded, allocating data for one channel A for primary modulation and allocating data for the other channel B for phase modulation. A channel allocated for phase modulation includes SACCH (low-speed associated channel).

(Embodiment 2)
In addition to the transmission rate improvement effect described in the first embodiment, the present invention has a specific effect that a part of data can be extracted in the delay detection process before the primary demodulation process in the OFDM receiver. In the second embodiment, a case where this unique effect is applied to the relay station apparatus will be described.

2.1 System Configuration FIG. 8 is a diagram showing a configuration of a wireless system according to the present embodiment. In FIG. 8, this system includes a base station device 801, a relay station device 802, and a plurality of terminal devices 803-1 and 803-2.

  The terminal device 803-1 transmits a signal 811 to the base station device 801 via the relay station device 802. The terminal device 803-1 can also transmit the signal 812 directly to the terminal device 803-2.

  When the relay station apparatus 802 receives the signal transmitted from the terminal apparatus 803-1, whether the received signal is directed to the base station apparatus 801 (811) or the terminal apparatus 803-2 ( 812) must be determined. If the received signal is directed to the base station apparatus 801 (811), the relay station apparatus 802 must amplify the signal and transmit the amplified signal to the base station apparatus 801. On the other hand, if the received signal is directed to the terminal device 803-2 (812), the relay station device 802 must stop transmitting it to the base station device 801.

  Here, when both the frequency of the signal 811 for the base station device 801 and the signal 812 for the terminal device 803-2 transmitted from the terminal device 803-1 are the same, the conventional relay station device is: If the received signal is once demodulated and decoded and the contents of the data are not confirmed, the received signal is directed to the base station device 801 (811) or directed to the terminal device 803-2 (812). I couldn't determine if there was.

  On the other hand, according to the present embodiment, due to the above-described effect, relay station apparatus 802 is one in which the received signal is directed to base station apparatus 801 without demodulating and decoding the received signal (811). Or the terminal device 803-2 (812).

2.2 Configuration of Relay Station Device FIG. 9 is a block diagram showing a configuration of relay station device 802 according to the present embodiment. In FIG. 9, the same components as those in FIG. 7 are denoted by the same reference numerals as those in FIG. 7, and detailed description thereof is omitted. Further, the terminal device 803-1 includes the OFDM transmission device illustrated in FIG. 6, and is phase-modulated by a signal 811 transmitted to the base station device 801 and a signal 812 transmitted to the terminal device 803-2. It is assumed that the shift amount in is different. This shift amount is assumed to be known in relay station apparatus 802.

  Relay station apparatus 802 shown in FIG. 9 includes reception antenna 201, reception RF section 202, synchronous detection section 203, GI removal section 204, S / P section 205, FFT section 206, delay detection section 207, The buffer 208, the determination unit 901, the amplification unit 902, and the transmission antenna 903 are mainly configured.

  The delay detection unit 207 detects a phase difference between the known symbol part of the symbol output from the FFT unit 206 and the known symbol part of the immediately preceding symbol stored in the buffer 208 (delay detection process), and represents the phase difference. k-bit data is output to the determination unit 901.

  The determination unit 901 determines whether the radio frequency signal received by the reception antenna 201 is directed to the base station apparatus 801 (811) based on the shift amount corresponding to the data output from the delay detection unit 207. Then, it is determined whether the terminal device 803-2 is directed (812).

  Then, determination section 901 outputs signal 811 directed to base station apparatus 801 to amplification section 902, and discards signal 812 directed to terminal apparatus 803-2.

  The amplification unit 902 amplifies the signal 811 output from the determination unit 901 and transmits the signal 811 from the transmission antenna 903 toward the base station apparatus 801.

2.3 Effects of the Embodiment As described above, according to the present embodiment, by using data that can be extracted in the delay detection processing, signal transmission can be performed without demodulating and decoding the received signal. The destination can be judged.

  The present invention is suitable for use in a base station device, a terminal device, and a relay station device used for mobile communication of the OFDM transmission scheme.

FIG. 1 is a block diagram showing a configuration of an OFDM transmission apparatus according to Embodiment 1 of the present invention. FIG. 1 is a block diagram showing a configuration of an OFDM receiving apparatus according to Embodiment 1 of the present invention. The figure which shows the constellation of the symbol by which the phase modulation process was carried out by the OFDM transmitter which concerns on Embodiment 1 of this invention. The figure which shows the constellation of the symbol by which the delay detection process was carried out by the OFDM receiver which concerns on Embodiment 1 of this invention. Block diagram showing another configuration of the OFDM transmitter according to Embodiment 1 of the present invention Block diagram showing another configuration of the OFDM transmitter according to Embodiment 1 of the present invention FIG. 3 is a block diagram showing another configuration of the OFDM receiving apparatus according to Embodiment 1 of the present invention. The figure which shows the structure of the system containing the relay station apparatus which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of the relay station apparatus which concerns on Embodiment 2 of this invention. The figure which shows the relationship between SNR and BER

DESCRIPTION OF SYMBOLS 100 OFDM transmitter 101 Encoding part 102 S / P (serial / parallel conversion) part 103 Primary modulation part 104 Phase modulation part 105 IFFT part 106 P / S (parallel / serial conversion) part 107 GI (guard interval) addition part 108 Transmission RF section 109 Transmission antenna 200 OFDM receiver 201 Reception antenna 202 Reception RF section 203 Synchronous detection section 204 GI (guard interval) removal section 205 S / P (serial / parallel conversion) section 206 FFT section 207 Delay detection section 208 Buffer 209 Phase correction unit 210 Primary demodulation unit 211 P / S (parallel / serial conversion) unit 212 Decoding unit 801 Base station apparatus 802 Relay station apparatus 803 Terminal apparatus

Claims (8)

An OFDM transmission apparatus that processes data in an OFDM (Orthogonal Frequency Division Multiplexing) transmission system and wirelessly transmits the obtained signal,
Encoding means for encoding the input data;
Primary modulation means for generating symbols by modulating the first encoded data, which is part of the data encoded by the encoding means, for each subcarrier;
Phase modulation means for rotating the phase of the symbol generated by the primary modulation means from the immediately preceding symbol by the shift amount represented by the second encoded data which is the remaining data encoded by the encoding means;
An OFDM transmitter comprising:   The OFDM transmission apparatus according to claim 1, wherein the second encoded data is a redundant bit obtained by an error correction encoding process.   The encoding means generates first encoded data by encoding first channel data, and generates second encoded data by encoding second channel data, which is a channel different from the first channel. The OFDM transmitter according to claim 1.   The OFDM transmission apparatus according to any one of claims 1 to 3, wherein the phase modulation means performs a phase rotation process on an OFDM symbol to which a guard interval is added. An OFDM receiver that processes a radio signal transmitted from the OFDM transmitter according to any one of claims 1 to 4 and extracts data,
Delay detection means for extracting the second encoded data from the phase difference between the symbol obtained from the received signal and the symbol immediately preceding it;
Phase correction means for reversely rotating the phase of the symbol obtained from the received signal by the shift amount represented by the second encoded data extracted by the delay detection means;
Primary demodulation means for demodulating a symbol whose phase has been reversely rotated by the phase correction means to extract the first encoded data;
Decoding means for decoding the first encoded data extracted by the primary demodulation means and the second encoded data extracted by the delay detection means;
An OFDM receiver comprising: An OFDM transmitter that processes data in an OFDM (Orthogonal Frequency Division Multiplexing) transmission method and wirelessly transmits the obtained signal; an OFDM receiver that processes a wireless signal transmitted from the OFDM transmitter and extracts data; An OFDM transmission system comprising:
The OFDM transmitter
Encoding means for encoding the input data;
Primary modulation means for generating symbols by modulating the first encoded data, which is part of the data encoded by the encoding means, for each subcarrier;
Phase modulation means for rotating the phase of the symbol generated by the primary modulation means from the immediately preceding symbol by the shift amount represented by the second encoded data which is the remaining data encoded by the encoding means. ,
The OFDM receiver
Delay detection means for extracting the second encoded data from the phase difference between the symbol obtained from the received signal and the symbol immediately preceding it;
Phase correction means for reversely rotating the phase of the symbol obtained from the received signal by the shift amount represented by the second encoded data extracted by the delay detection means;
Primary demodulation means for demodulating a symbol whose phase has been reversely rotated by the phase correction means to extract the first encoded data;
Decoding means for decoding the first encoded data extracted by the primary demodulation means and the second encoded data extracted by the delay detection means,
OFDM transmission system. A base station device, a terminal device, and a relay station device that receives a signal wirelessly transmitted from the terminal device, amplifies and wirelessly transmits the signal to the base station device, and the terminal device is another terminal. A communication system for wirelessly transmitting a signal to a device,
The terminal apparatus includes the OFDM transmission apparatus according to any one of claims 1 to 4,
The relay station device
Delay detection means for extracting the second encoded data from the phase difference between the symbol obtained from the received signal and the symbol immediately preceding it;
Whether the received signal is directed to the base station apparatus or the other terminal apparatus based on the shift amount represented by the second encoded data taken out by the delay detection means Determining means for determining
Amplifying means for amplifying a signal determined to be directed to the base station apparatus and transmitting the signal from a transmission antenna toward the base station apparatus;
Communications system. OFDM communication in which data is processed in an OFDM (orthogonal frequency division multiplexing) transmission apparatus, and the obtained signal is transmitted wirelessly, and in the OFDM reception apparatus, a wireless signal transmitted from the OFDM transmission apparatus is processed and data is extracted. A method,
In the OFDM transmitter,
An encoding process for encoding the input data;
A primary modulation step of generating symbols by modulating the first encoded data, which is a part of the data encoded in the encoding step, for each subcarrier;
A phase modulation step of rotating the phase of the symbol generated in the primary modulation step from the immediately preceding symbol by the shift amount represented by the second encoded data that is the remaining data encoded in the encoding step,
In the OFDM receiver,
A delay detection step of extracting the second encoded data from the phase difference between the symbol obtained from the received signal and the symbol immediately preceding it;
A phase correction step of reversely rotating the phase of the symbol obtained from the received signal by the shift amount represented by the second encoded data extracted in the delay detection step;
A primary demodulation step of demodulating a symbol whose phase has been reversely rotated in the phase correction step to extract the first encoded data;
A decoding step of decoding the first encoded data extracted in the primary demodulation step and the second encoded data extracted in the delay detection step;
OFDM communication method.

Images