JP4531614B2 - Transmitting apparatus and receiving apparatus - Google Patents

Description

  The present invention relates to the technical field of wireless communication, and more particularly, to a transmission device and a reception device that enable coexistence of single-carrier and multi-carrier systems.

  In a third generation communication system represented by IMT-2000 (International Mobile Telecommunications-2000), an information transmission rate of 2 Mbps is realized using a 5 MHz frequency band in the downlink. In IMT-2000, a single-carrier wideband code division multiple access (W-CDMA) system is employed. In addition, a method called high speed downlink packet access (HSDPA) is also adopted. HSDPA employs an adaptive modulation and channel coding (AMC) method, an automatic packet repeat request (ARQ) method in the MAC layer, and the like, thereby increasing the transmission rate and increasing the transmission rate. We are trying to improve quality.

  On the other hand, research on a multi-carrier system using a plurality of subcarriers is currently being conducted. In particular, the Orthogonal Frequency Code Division Multiplexing (OFCDM) scheme is promising for future communication systems. In the OFCDM system, data is transmitted in parallel on a large number of low-speed subcarriers, and two-dimensional spreading in the frequency and time domains is performed to further increase the speed and quality.

A publicly known example of a communication system in which single carrier terminals and multicarrier terminals can be mixed is described in Patent Document 1, for example.
No. 2004-72455

  Accordingly, it is conceivable to provide a service of an OFCDM system (referred to as a new system for convenience) instead of or in addition to a W-CDMA system (referred to as an old system for convenience). In this case, it is expected that an area where a plurality of old and new systems coexist will appear. Even if the new system is changed to the old system, there will be periods of coexistence of both systems, at least during the transition period. One method for coexisting the old and new systems is to assign different frequency bands to the old system and the new system, respectively, as shown in FIG. In FIG. 1A, four 5 MHz bands are prepared, two being assigned to the operator (carrier) of the old system, and the other two being assigned to the operator of the new system. Such a method is advantageous if a band that can be newly allocated remains in the frequency band. The above-mentioned patent document is premised on the existence of such a convenient band.

  However, depending on the region, time, or country, such frequency bands may not be allocated separately. For example, as shown in FIG. 1B, the frequency band is entirely used in the old system. FIG. 1B shows that two 5 MHz bands are prepared and both of them are already assigned to the operator of the old system. In the situation as shown in FIG. 1B, it is technically possible to open one of the two bands and assign it to a new system operator. However, this is not always possible. For example, when a resource having only a 5 MHz band is already used by one operator, such frequency band allocation is difficult.

  The present invention has been made in view of the above-mentioned problems, and the problem is that the first communication system of the single carrier system and the second communication system of the multicarrier system share at least a part of the frequency band. However, it is an object of the present invention to provide a transmission device and a reception device that can coexist.

  In the present invention, a transmission device that can be used in the first communication system of the single carrier scheme and the second communication system of the multicarrier scheme is used. The apparatus transmits a single carrier packet on a downlink channel, and after the first retransmission waiting period has elapsed, transmits a single carrier packet on a downlink channel and a first retransmission unit that retransmits the single carrier packet on demand. And second retransmission means for retransmitting the multi-carrier packet in response to a request after the second retransmission waiting period has elapsed. The second retransmission means transmits one or more multicarrier packets during the first retransmission waiting period.

  ADVANTAGE OF THE INVENTION According to this invention, the 1st communication system of a single carrier system and the 2nd communication system of a multicarrier system can share at least one frequency band in the same area.

  According to one aspect of the present invention, a single carrier packet is retransmitted in response to a request after the first retransmission waiting period has elapsed. Multi-carrier packets are also retransmitted in response to a request after the second retransmission waiting period has elapsed. One or more multi-carrier packets are transmitted during the first retransmission waiting period. Since the single carrier packet and the multicarrier packet are transmitted in different time slots in time, both signals are transmitted without interfering with each other. Coexistence of both systems can be realized by transmitting not only packets of the same system but also packets of other systems within the first retransmission waiting period. Therefore, for example, even if there is no unallocated band as shown in FIG. 1B, an OFCDM system can coexist in the same region using the existing W-CDMA band. . Further, since the packet is not retransmitted later than the first retransmission waiting period with respect to the first communication system, even if the new second communication system coexists, the old first communication system Can be operated as before.

  According to one aspect of the present invention, the transmission time interval of a single carrier packet is equal to the transmission time intervals of a plurality of multicarrier packets. Further, one single carrier packet and a plurality of multicarrier packets are transmitted alternately.

  According to one aspect of the present invention, the control channel of the first communication system is shared by the first and second communication systems. The control channel is transmitted continuously in time. Thereby, resources can be saved.

  According to one aspect of the present invention, the first control channel for the first communication system and the second control channel for the second communication system are transmitted separately. In addition, the first control channel is transmitted together with the single carrier packet, and the second control channel is transmitted together with the multicarrier packet. Thereby, inter-system interference can be greatly reduced.

  According to one aspect of the present invention, means for Fourier transforming a signal representing a single carrier packet, filter means for band-limiting the signal after Fourier transform, a signal after band limitation, and a signal representing a multicarrier packet And a means for performing inverse Fourier transform on the time-multiplexed signal are further provided in the transmission device. Thereby, the elements related to transmission of the first and second communication systems can be shared. Further, by performing bandwidth limitation on a single carrier packet in the frequency domain, it is possible to reduce the calculation burden required for bandwidth limitation processing.

  According to an aspect of the present invention, the transmission apparatus further includes encoding means for selecting and encoding one of signals representing single carrier or multicarrier packets. Thereby, the encoding means can be shared by both systems.

  According to one aspect of the present invention, a transmission apparatus that can be used in a first communication system using a single carrier scheme and a second communication system using a multicarrier scheme performs a Fourier transform on a signal representing a single carrier packet, and performs band limitation. Then, when time-multiplexing with a signal representing a multicarrier packet and transmitting the multiplexed signal after inverse Fourier transform, a receiving device that receives the transmitted signal performs Fourier transform on the received signal, A signal representing a single carrier packet and a signal representing a multicarrier packet are temporally separated, and a signal representing a single carrier packet is subjected to inverse Fourier transform.

  FIG. 2 shows a general view of a transmitter according to an embodiment of the present invention. The transmitter is typically provided in a base station and transmits a downlink channel, but may be provided in a mobile station. In this embodiment, the transmitter transmits a W-CDMA packet and an OFCDM packet, but more generally, as a transmitter that transmits a single carrier packet and a multicarrier packet. It is extensible.

  The transmitter includes a first baseband processing unit 201, a second baseband processing unit 202, a multiplexing unit 204, and an RF transmission unit 206. The RF transmitter 206 includes a digital-analog converter 210, a quadrature modulator 212, a local oscillator 214, a bandpass filter 216, a mixer 218, a local oscillator 220, a bandpass filter 222, and a power amplifier 224. Have.

  As will be described later, the first baseband processing unit 201 is a baseband signal processing unit related to the W-CDMA system, and performs signal processing related to the HSDPA system. For example, parameters necessary for AMC and ARQ are determined. Further, mapping in the Internet protocol (IP) and signal processing related to the MAC layer and the physical layer are also performed.

  The second baseband processing unit 202 is a baseband signal processing unit related to the OFCDM system, as will be described later. In this signal processing unit, for example, determination of parameters necessary for AMC and ARQ, mapping in the Internet protocol, signal processing related to the MAC layer and the physical layer, and the like are performed.

  The multiplexing unit 204 selects and outputs one of the signals output from the first and second baseband processing units 201 and 202, thereby time-multiplexing those signals.

  The RF transmission unit 206 performs processing for transmitting a transmission target baseband signal as a radio signal. The digital / analog converter (D / A) converts a digital signal into an analog signal. The quadrature modulator 210 generates an in-phase component (I) and a quadrature component (Q) of an intermediate frequency from the signal input thereto. The band pass filter 212 removes excess frequency components for the intermediate frequency band. The mixer 218 uses the local oscillator 220 to convert (up-convert) an intermediate wave number signal into a high frequency signal. The band pass filter 222 removes excess frequency components. The power amplifier 224 amplifies signal power in order to perform wireless transmission from the antenna 226.

  FIG. 3 shows details of the first and second baseband processing units 201 and 202 according to an embodiment of the present invention. In this example, a control channel for a W-CDMA system (referred to as a first communication system) is also shared by an OFCDM system. The first baseband processing unit 201 includes a convolutional encoder 302, a data modulation unit 304, spreading units 306 and 308, a multiplexing unit 310, and a band limiting filter 312. In addition, the first baseband processing unit 201 includes a turbo encoder 322, a data modulator 324, a spreading unit 326, a multiplexing unit 330, a band limiting filter 332, and a transmission TTI control unit 334. The second baseband processing unit 202 includes a turbo encoder 342, a data modulator 344, an interleaver 345, a serial-parallel conversion unit 347, a spreading unit 349, a fast inverse Fourier transform unit 350, and guard interval insertion. Unit 352 and transmission TTI control unit 354.

  The convolutional encoder 302 performs encoding to increase error resistance of data transmitted through the control channel. The data modulator 304 modulates the control channel using, for example, a QPSK modulation method. Any suitable modulation method may be adopted, but since the amount of information of the control channel is relatively small, the QPSK modulation method with a small number of modulation multi-values is adopted in this embodiment. The spreading unit 306 performs code spreading by multiplying the control channel by a predetermined spreading code. Similarly, spreading section 308 performs code spreading by multiplying a pilot channel by a predetermined spreading code. The multiplexing unit 310 multiplexes the spread control channel and the spread pilot channel. Multiplexing may be performed using one or more of time multiplexing, frequency multiplexing, and code multiplexing. The band limiting filter 312 is composed of, for example, a root Nyquist filter and performs band limiting.

  The turbo encoder 322 of the first baseband processing unit 201 performs encoding for improving error tolerance of data transmitted through the data channel. The data modulator 324 modulates transmission data with an appropriate modulation scheme. The modulation scheme may be any suitable modulation scheme such as QPSK, 16QAM, 64QAM, or the like. The spreading unit 326 code spreads the data channel. Multiplexer 330 multiplexes the code-spread pilot channel and data channel as necessary. For example, when the transmission beams of the control channel and the data channel are different and the propagation paths of the two are significantly different, the pilot channel for the data channel may be transmitted in addition to the pilot channel for the control channel. The band limiting filter 332 is composed of a root Nyquist filter, for example, and performs band limiting. The transmission TTI control unit 334 gives a data channel to the multiplexing unit 204 on the basis of a transmission time interval (TTI) in the first W-CDMA system. TTI defines the duration of one packet (typically one TTI = the duration of one packet). The TTI of the first communication system may be 2 ms, for example. Details of the operation of the transmission TTI control unit will be described later.

  Similarly, the turbo encoder 342 of the second baseband processing unit performs encoding to improve error tolerance of data transmitted on the data channel of the OFCDM system (referred to as the second communication system). I do. The data modulator 344 modulates transmission data with an appropriate modulation scheme. The modulation scheme may be any suitable modulation scheme such as QPSK, 16QAM, 64QAM, or the like. Interleaver 345 changes the order in which signals representing the data channels to be transmitted are arranged. The serial / parallel converter (S / P) 347 converts a serial signal sequence (stream) into a plurality of parallel signal sequences. The spreading unit 349 code spreads the data channel. The fast inverse Fourier transform unit 350 performs fast inverse Fourier transform on the input signal to perform OFDM modulation. The guard interval insertion unit 352 creates a symbol in the OFDM scheme by adding a guard interval to a signal to be transmitted. As is well known, the guard interval is obtained by duplicating the beginning or end of the symbol to be transmitted. The transmission TTI control unit 354 provides the data channel to the multiplexing unit 204 based on the transmission time interval (TTI) in the second communication system. As with the first communication system, the TTI defines the duration of one packet (typically one TTI = the duration of one packet). The TTI of the second communication system may be 0.25 ms, for example. Details of the operation of the transmission TTI control unit will also be described later.

  The control channel input to the first baseband processing unit 201 is convolutionally encoded, QPSK modulated, code spread, and multiplexed by the multiplexing unit 310 together with the spread pilot channel. The multiplexed signal is band-limited and provided to the multiplexing unit 204.

  The data channel input to the first baseband processing unit 201 is encoded by the turbo encoder 322, modulated, spread, band-limited, and input to the transmission TTI control unit 334. The transmission TTI control unit 334 provides a data channel from various users to the multiplexing unit 204 for each packet, or provides a retransmission target packet to the multiplexing unit 204 in order to retransmit a transmitted packet in response to a request.

  The data channel input to the second baseband processing unit 202 is encoded by the turbo encoder 342, modulated, rearranged by the interleaver 345, parallelized by the serial-parallel conversion unit 347, and sub-carrier components are separated. Diffused. The spread data channel is modulated by the fast inverse Fourier transform unit 350 using the OFDM method, and a guard interval is added to the modulated signal, which is input to the transmission TTI control unit 354. The transmission TTI control unit 354 provides a data channel from various users to the multiplexing unit 204 for each packet, or provides a retransmission target packet to the multiplexing unit 204 in order to retransmit a transmitted packet in response to a request.

  In this way, baseband processing is performed, multiplexed by the multiplexing unit 204, and wirelessly transmitted from the antenna 226 via the RF transmission unit 206 of FIG.

  The data channel transmitted from the first communication system is a single carrier packet. The data channel transmitted from the second communication system is a multicarrier packet. Therefore, the frequency spectrum waveforms of the input signal of the transmission TTI control unit 334 and the input signal of the transmission TTI control unit 354 are significantly different (FIG. 4). Therefore, if these signals are transmitted in the same frequency band at the same time, it is expected that interference between systems will become very large.

  By the way, in a W-CDMA 3G communication system (first communication system) such as IMT2000, an automatic repeat request (ARQ: Automatic Repeat Request) control method is adopted, and after a packet is transmitted, as necessary. The same packet is retransmitted after a predetermined period. The predetermined period or the time waiting for retransmission (retransmission waiting period) is defined by the standard to be a period of 5 TTIs (5 packets) (in other words, the DSCH round trip time (RTT) is 6 TTIs). It needs to be.) Within this retransmission waiting period, another packet related to the same or different user is transmitted. The inventors of the present invention pay attention to this point, and have found that the coexistence of both systems can be realized by transmitting not only packets of the same system but also packets of other systems within the retransmission waiting period.

FIG. 5 shows a conceptual diagram of a packet transmitted by the transmitter of FIGS. FIG. 5 shows a packet related to the control channel and a data channel packet used in the first and second communication systems. In the figure, the horizontal direction (left-right direction) represents the time direction. As described above, the control channel is shared by both the first and second communication systems and is transmitted continuously in time. Packets related to the data channel are time-multiplexed and transmitted between the first and second communication systems. In the illustrated example, a state in which a packet (single carrier packet) of the first communication system and a packet (multicarrier packet) of the second communication system are alternately transmitted is shown. In the figure, A1, A2,. . . A single carrier packet is transmitted in the time slot indicated by B1, B2,. . . Multi-carrier packets are transmitted in the time slot indicated by. In this embodiment, the TTI of the single carrier packet is 2 ms, and the TTI of the multicarrier packet is 0.25 ms. As shown in the enlarged view, each of the time slots B _i (i = 1, 2,...) For the multicarrier packet has eight time slots B _i1 , B _i2,. . . , B _i8 are included. Therefore, after transmitting one single carrier packet, eight multicarrier packets are transmitted, then the single carrier packet is transmitted again, and the transmission TTI controllers 334 and 336 Multiplexer 204 operates. In addition, the specific numerical value of the transmission time interval TTI regarding each communication system is only an example, and various other values may be adopted.

  When such signal transmission is performed, the first communication system can satisfactorily receive the control channel and the data channel. However, due to this control channel, the data channel of the second communication system is subject to some intersystem interference. However, since the amount of information in the control channel is small, such interference will be negligible in many cases.

Regarding the retransmission of the packet, as shown in the figure, the single carrier packet is retransmitted the same single carrier packet after the elapse of 5 TTIs after the transmission. For example, a single carrier packet transmitted in time slot A1 is retransmitted in time slot A4. Therefore, the existing specification regarding the first communication system may not be changed. The multicarrier packet is also retransmitted after 5 TTIs (after TTIs in the second communication system). In this case, as shown in the enlarged view of FIG. 5, the packet transmitted by the B ₂₁ in the time slot A2 immediately after the time slot B2, is retransmitted in the time slot B _27. Similarly, a packet transmitted in time slot B ₂₂ is retransmitted in time slot B ₂₈ . However, packets transmitted in the time slot _{B 23} is retransmitted _{B 31} in time slot B3 immediately after the time slot A3. Similarly, packets transmitted in time slots B ₂₄ , B ₂₅ , B ₂₆ , B ₂₇ , B ₂₈ are also retransmitted in time slots B ₃₂ , B ₃₃ , B ₃₄ , B ₃₅ , B ₃₆ after time slot A 3. Is done. Therefore, the packets transmitted in the time slots B ₂₁ and B ₂₂ are retransmitted without delay, but the retransmission of the packets transmitted in the time slots B _{23 to} B ₂₈ is delayed by about 2 ms (8 packets). . However, note that this delay is much shorter than the retransmission bandwidth period of the first communication system (5 TTI = 10 ms), and by allowing this delay, system overlay can be realized. Cost.

  In FIG. 5, the packets of the first and second communication systems are alternately transmitted every 2 ms, but the present invention is not limited to such an aspect. FIG. 6 is a diagram illustrating another aspect of the transmission method. In FIG. 6, the packets of the first and second communication systems are alternately transmitted every 6 ms. That is, after three single carrier packets are transmitted over time slots A1, A2 and A3, 8 × 3 = 24 multicarrier packets are transmitted over time slots B1, B2 and B3, and so on. In addition to the illustration, any suitable transmission method may be used. More generally, one or more single carrier packets and one or more multicarrier packets may be transmitted during the retransmission waiting period for single carrier packets.

  FIG. 7 shows first and second baseband processing units 201 and 202 according to an embodiment of the present invention. Elements that have already been described with reference to FIG. 3 are given similar reference numerals and redundant description is omitted. In the present embodiment, a control channel is separately prepared for each of the first and second communication systems, and they are transmitted while being time-multiplexed with the data channel. Note that the multiplexing units 310 and 330 in FIG. 3 are integrally illustrated as the multiplexing unit 310 in FIG. Therefore, in FIG. 7, the convolutional encoder 362, the data modulator 364, the interleaver 365, the serial / parallel converter 367, the spreading unit 369, and the multiplexing unit 348 are provided for the second control channel. It is drawn. Since these elements are the same as those already described, redundant description is omitted.

  FIG. 8 is a conceptual diagram of a packet transmitted from the transmitter according to the present embodiment. As shown, the data channel is transmitted alternately between the first and second communication systems, as in FIG. In this embodiment, the control channel is also transmitted alternately in accordance with the switching. That is, the single carrier packet and the control channel are multiplexed by the multiplexing unit 310, and transmission is started simultaneously and transmission is stopped simultaneously. Similarly, the multicarrier packet and the control channel are multiplexed by the multiplexing unit 348, transmission starts simultaneously, and transmission stops simultaneously. By adopting such a transmission method, it is possible to suppress inter-system interference caused by the control channel.

  FIG. 9 shows details of a baseband processing unit according to an embodiment of the present invention. Elements that have already been described with reference to FIG. 3 are given similar reference numerals and redundant description is omitted. It should be noted that in FIG. 9, elements relating to the control channel are not drawn for simplicity. In FIG. 9, an interleaver 902, a fast Fourier transform unit 904, and a band limiting filter 906 are depicted on the first baseband processing unit 201 side.

  Interleaver 902 changes the arrangement of data channel signals according to a predetermined pattern.

  The fast Fourier transform unit 904 performs fast Fourier transform on the data channel after spreading. As a result, the time domain input signal is converted into a frequency domain signal and output.

  The band limiting filter 906 performs band limiting in the same manner as the band limiting filters 312 and 332 in FIGS. 3 and 7, but the band limiting filter 906 performs band limiting in the frequency domain, and performs this in the time domain. This is different from the band limiting filter 312 or the like.

  In the present embodiment, processing relating to the multiplexing unit 204, the fast inverse Fourier transform unit 350, and the guard interval insertion unit 352 is performed in common by the first and second baseband processing units 201 and 202. Therefore, it should be noted that the transmission TTI control units 334 and 354 are drawn on the input side. In this embodiment, the processing after the multiplexing unit 204 is performed in common for the first and second baseband processing units 201 and 202, and a fast Fourier transform unit 904 is provided between the spreading unit 326 and the band limiting filter 906. It has been. In the present embodiment, the multi-carrier packet is the same as that already described, and therefore redundant description is omitted. The single carrier packet is processed by the fast Fourier transform unit 904 and the fast inverse Fourier transform unit 350, and thus is not modulated by the OFDM method. In this way, part of signal processing is shared, and the band limiting process of the single carrier packet is performed in the frequency domain by the band limiting filter 906. It should be particularly noted that the calculation load of the band limiting filter 906 is much lighter than the calculation load of the band limiting filter 312 in FIG. In the bandwidth limitation process in the time domain, in order to obtain a value after bandwidth limitation at each time point, it is necessary to weight-add a plurality of samples before and after that time point. On the other hand, in the band limiting process in the frequency domain, the band-limited value at each frequency can be immediately obtained by multiplying one frequency sample to be processed by one weighting factor.

  FIG. 10 shows a transmitter in which elements are further shared as compared with the baseband processing unit shown in FIG. Duplicate explanations for already described elements are omitted. In FIG. 10, a buffer 1002 and a separation unit 1004 are newly drawn.

  The buffer 1002 receives and temporarily stores data channels related to single carrier packets and multicarrier packets. These are selectively input to the turbo encoder in accordance with each transmission time interval TTI.

  Separating section 1004 time-divides the data channel related to the single carrier packet and the data channel related to the multicarrier packet in accordance with each time.

  The large sharing of the processing elements as shown in the figure is mainly based on the time multiplexing of the output signals from the first and second baseband processing units 201 and 202. That is, there are many processing elements that do not require simultaneous processing.

  FIG. 11 shows an overall view of a receiver according to an embodiment of the present invention. Such a receiver is typically provided in a mobile station, but may be provided in a base station. The receiver according to the present embodiment receives signals transmitted from the transmitters of FIGS. In this embodiment, this receiver is provided in a mobile station, and antenna diversity using two antennas is performed in order to improve signal quality. Since signals received for each antenna are similarly processed by similar processing elements, the signal processing elements and functions for one antenna are described as a representative. The mobile station includes an RF reception unit 1102 connected to one of the antennas, a first baseband processing unit 1111, and a second baseband processing unit 1112. The RF receiving unit 1102 includes a low noise amplifier (LNA) 1103, a mixer 1104, a local oscillator 1105, a band pass filter 1106, an automatic gain control unit 1107, a quadrature detector 1108, a local oscillator 1109, analog digital A conversion unit 1110.

  The RF receiver 1002 performs processing such as power amplification, frequency conversion, and band limitation on the high-frequency signal received by the antenna. The low noise amplifier 1103 appropriately amplifies the signal received by the antenna. The amplified signal is converted to an intermediate frequency by the mixer 1104 and the local oscillator 1105 (down-conversion). The band pass filter 1106 removes unnecessary frequency components. The automatic gain control unit (AGC) 1107 controls the gain of the amplifier so that the signal level is properly maintained. The quadrature detector 1108 uses the local oscillator 1109 to perform quadrature demodulation based on the in-phase component (I) and quadrature component (Q) of the received signal. An analog / digital converter (A / D) 1110 converts an analog signal into a digital signal.

  The first baseband processing unit 1111 performs baseband processing of signals related to a single carrier communication system (for example, a W-CDMA system) that is the first communication system. In addition, protocol processing related to IP connection and the MAC layer and physical layer is also performed. Baseband processing includes, for example, determining parameters necessary for AMC and ARQ.

  The second baseband processing unit 1112 performs baseband processing of signals related to a multicarrier communication system (for example, an OFCDM system) that is the second communication system. In addition, protocol processing related to IP connection and the MAC layer and physical layer is also performed. Baseband processing includes, for example, determining parameters necessary for AMC and ARQ.

  The mobile station may be a terminal dedicated to the first or second communication system, or may be a terminal that can be shared by both systems. The dedicated terminal includes only one of the first and second baseband processing units. The shareable terminal includes both the first and second baseband processing units.

  FIG. 12 shows details of the first baseband processing unit 1111 shown in FIG. FIG. 12 shows a band limiting filter 1202, a path searcher 1204, a despreading unit 1206, a channel estimation unit 1208, a rake combining unit 1210, a combining unit 1212, and a turbo decoder 1214.

  The band limiting filter 1202 is constituted by a root Nyquist filter, for example, and performs band limiting. The path searcher 1204 searches for a path in the multipath propagation path. The path search is performed, for example, by examining a delay profile. The despreading unit 1206 despreads the signal in accordance with the path timing. The channel estimation unit 1208 performs channel estimation using the path timing. Channel estimation section 1208 outputs a control signal for adjusting the amplitude and phase so that fading generated in the propagation path is compensated according to the estimation result. The rake combiner 1210 combines and outputs the despread signals while compensating for each path.

  The combining unit 1212 combines received signals obtained for each antenna. Any suitable synthesis method may be employed. The synthesis method may include, for example, a selection method, an equal gain synthesis method, a maximum ratio synthesis method, and the like.

  The turbo decoder 1214 decodes the received signal and demodulates the data.

  The signal received by each antenna is processed for each antenna as described above. The received signal is converted into a digital signal by processing such as amplification, frequency conversion and band limitation in the RF receiver. The digital signal is band-limited for each subcarrier, despread, and rake-combined for each path. A signal for each subcarrier after rake combining is obtained for each antenna, they are combined and decoded by the combining unit 1212, and the transmitted signal is restored.

  FIG. 13 shows details of the second baseband processing unit 1112 of FIG. In FIG. 13, a symbol timing detection unit 1302, a guard interval removal unit 1304, a fast Fourier transform unit 1306, a demultiplexer or separation unit 1308, a channel estimation unit 1310, a despreading unit 1312, and a parallel / serial conversion unit A (P / S) 1314, a despreading unit 1316, combining units 1318 and 1319, a deinterleaver 1320, a turbo encoder 1322, and a Viterbi decoder 1324 are depicted.

  The symbol timing detection unit 1302 detects the timing of the symbol (symbol boundary) based on the digital signal.

  The guard interval removing unit 1304 removes a portion corresponding to the guard interval from the received signal.

  The fast Fourier transform unit 1306 performs fast Fourier transform on the input signal and performs demodulation of the OFDM method. As a result, the received signal is converted into a signal in the frequency domain.

  The demultiplexer 1308 separates the pilot channel, control channel, and data channel that are multiplexed in the received signal. This separation method is performed in correspondence with multiplexing on the transmission side (processing contents in the multiplexing unit 310 and the like in FIG. 3).

  Channel estimation section 1310 estimates the state of the propagation path using the pilot channel, and outputs a control signal for adjusting the amplitude and phase so as to compensate for channel fluctuation. This control signal is output for each subcarrier.

The despreading unit 1312 despreads the data channel after channel compensation for each subcarrier. The code multiplexing number is assumed to be C _mux .

  The parallel / serial converter (P / S) 1314 converts a parallel signal sequence into a serial signal sequence.

  The despreading unit 1316 despreads the channel compensated control channel for each subcarrier.

  The combining units 1318 and 1319 combine the signals processed for each antenna by an appropriate combining method such as a selection method, an equal gain combining method, a maximum ratio combining method, or the like.

  The deinterleaver 1320 changes the order in which signals are arranged according to a predetermined pattern. The predetermined pattern corresponds to a reverse pattern of rearrangement performed by an interleaver (eg, 345 in FIG. 3) on the transmission side.

  The turbo encoder 1322 and the Viterbi decoder 1324 decode the traffic information data and the control information data, respectively.

  The signal received by the antenna is converted into a digital signal through processing such as amplification, frequency conversion, band limitation, and orthogonal demodulation in the RF receiver. The signal from which the guard interval is removed is demodulated by the OFDM method by the fast Fourier transform unit 1306. The demodulated signal is separated into a pilot channel, a control channel, and a data channel by a separation unit 1308. The pilot channel is input to the channel estimator, and a control signal that compensates for fluctuations in the propagation path is output for each subcarrier therefrom. The data channel is compensated using a control signal, despread for each subcarrier, and converted to a serial signal. The converted signal is rearranged by the deinterleaver 1320 in the reverse pattern to the rearrangement performed by the interleaver, and decoded by the turbo decoder 1322. Similarly, in the control channel, channel fluctuation is compensated by the control signal, despread, and decoded by the Viterbi decoder 1324. Thereafter, signal processing using the restored data and the control channel is performed.

  FIG. 14 illustrates a baseband processing unit of a receiver according to an embodiment of the present invention. Elements already described in FIGS. 12 and 13 are given the same reference numerals, and redundant descriptions thereof are omitted. The receiver according to the present embodiment receives signals from the transmitter shown in FIGS. Therefore, the signal transmitted from the transmitter and received by the receiver is a signal obtained by time-multiplexing a single carrier packet and a multicarrier packet and then inverse Fourier transforming. In FIG. 14, a demultiplexer 1402, a band limiting filter 1403, a fast inverse Fourier transform unit 1404, and a deinterleaver 1406 are newly drawn. Elements related to the control channel are not drawn for simplicity of illustration.

  Similar to the demultiplexer 1308 described with reference to FIG. 13, the demultiplexer 1402 separates the pilot channel, the control channel, and the data channel multiplexed in the received signal. Furthermore, the demultiplexer 1402 also temporally separates and outputs the single carrier packet that has been time multiplexed.

  The band limiting filter 1403 performs band limiting processing on the signal (time-separated signal) input thereto in the frequency domain. Similar to the band limiting filter 906 in FIG. 9, the band limiting process performed here can be performed very easily.

  The fast inverse Fourier transform unit 1404 performs fast Fourier inverse transform on the signal related to the single carrier packet after band limitation. Thereby, the signal regarding a single carrier packet is converted into the signal of a time domain.

  The deinterleaver 1406 changes the order in which signals are arranged according to a predetermined pattern. The predetermined pattern corresponds to a reverse pattern of rearrangement performed by a transmission-side interleaver (such as 902 in FIG. 9).

  The signal received by the antenna is converted into a digital signal through processing such as amplification, frequency conversion, band limitation, and orthogonal demodulation in the RF receiver. The fast Fourier transform unit 1306 converts the signal from which the guard interval is removed into a frequency domain signal. As for the multicarrier packet, demodulation of the OFDM method is performed. The signal converted into the frequency domain signal is temporally separated into a multicarrier packet (including a pilot channel, a control channel, and a data channel) and a single carrier packet by a separation unit 1308. Since the same processing as that described in FIG. 13 is performed for the multicarrier packet, redundant description is saved.

  The separated single carrier packet is band-limited in the frequency domain by the band-limiting filter 1202 and then subjected to inverse Fourier transform. By this conversion, the single carrier packet is converted into a time domain signal. The converted signal is despread, channel compensated, deinterleaved and then decoded.

  In the first to fifth embodiments, a plurality of systems coexist typically in the downlink. In the sixth embodiment described below, a plurality of systems typically coexist in the uplink. In the uplink, apart from high-speed and high-quality channel, there is a strong demand for lower power consumption of mobile stations. In this embodiment, a variable spreading factor chip repetition factor CDMA (VSCRF-CDMA: Variable Spreading Factors-CDMA) system that can realize orthogonalization in the frequency domain by a single carrier system is adopted for uplink. The configuration and operation of the transmitter and receiver used for this uplink are almost the same as those of a direct sequence CDMA (DS-CDMA) system transmitter and receiver, but it is related to spreading and despreading. Processing contents are very different.

  FIG. 15 is a block diagram of a spreading unit used in a VSCRF-CDMA transmitter. Accordingly, the operation of the spreading unit described below is typically performed at the mobile station. The spreading unit includes a code multiplying unit 1602, an iterative combining unit 1604, and a phase shifting unit 1606.

  The code multiplier 1602 multiplies the transmission signal by a spreading code. In FIG. 15, the multiplier 1612 multiplies the transmission signal by a channelization code determined under a given code spreading factor SF. Furthermore, the multiplier 1614 multiplies the transmission signal by the scramble code. The code spreading factor SF in the present embodiment is appropriately set according to the communication environment. More specifically, the code spreading factor SF may be set based on one or more of a propagation path state, a cell configuration, a traffic amount, and a radio parameter. The code spreading factor SF may be set by the base station or the mobile station. However, when information managed on the base station side such as traffic volume is used, it is preferable to determine the code spreading factor at the base station.

  The iterative combining section 1604 compresses the spread transmission signal in terms of time and repeats it a predetermined number of times (CRF times). The configuration and operation when the number of repetitions CRF is equal to 1 are equal to those in the normal DS-CDMA system (however, when CRF = 1, no phase shift is required in the phase shift unit).

  The phase shifter 1606 shifts (shifts) the phase of the transmission signal by a predetermined frequency. The phase amount to be shifted is set uniquely for each mobile station.

  FIG. 16 is a block diagram of a despreading unit used in a VSCRC-CDMA receiver. This despreading unit typically operates in a base station. The despreading unit includes a phase shift unit 1702, an iterative combining unit 1704, and a code despreading unit 1706.

  Phase shift section 1702 multiplies the received signal by the phase amount set for each mobile station, and separates the received signal into a signal for each mobile station.

  The iterative combining unit 1704 expands the repeated data in time (uncompresses) and restores the uncompressed data.

  The code despreading section 1706 performs despreading by multiplying the received signal by the spreading code for each mobile station.

FIG. 17 is a diagram for explaining main operations in the VSCRF-CDMA system. For convenience of explanation, one data group having a signal sequence after code spreading is represented by d ₁ , d ₂ ,. . . , D _Q and the period of each data d _i (i = 1,..., Q) is T _S. One piece of data d _i may correspond to one symbol, or any other appropriate information unit. This group of signal sequences has a period corresponding to T _S × Q as a whole. This signal series 1802 corresponds to an input signal to the iterative combining unit 1604. This signal sequence is temporally compressed to 1 / CRF and converted so that the compressed signal is repeated over a period of T _S × Q. The converted signal sequence is represented by 1804 in FIG. FIG. 17 also shows the period of the guard interval. Temporal compression can be performed using, for example, a frequency that is CRF times higher than the clock frequency used for the input signal. Thereby, the period of the individual data d _i is compressed to T _S / CRF (however, it is repeated CRF times). The compressed and repeated signal sequence 1804 is output from the iterative combining unit 1604, input to the phase shifting unit 1606, shifted by a predetermined phase amount, and output. The phase amount is set for each mobile station, and is set so that uplink signals for each mobile station are orthogonal to each other on the frequency axis. As a result, the frequency spectrum in the received signal of the uplink or base station is generally as shown by 1806 in FIG. In the figure, the band shown as the spread bandwidth indicates a band that will be occupied if the spread signal sequence 1802 is transmitted as it is. The spectrum at the stage of time compression and repetition (the spectrum of the output signal of the repetition combining unit 1604) occupies a narrow band, but the band is common to all mobile stations. By shifting the narrow-band spectrum by the phase amount specific to the mobile station, the bands can be prevented from overlapping each other. That is, by performing time compression, repetition, and phase shift, the frequency band related to each mobile station can be narrowed, and the frequency spectrum related to each mobile station can be arranged in a comb shape, and orthogonalization on the frequency axis Can be realized.

  The operation on the receiving side is the reverse of that on the transmitting side. That is, in accordance with the phase amount for each mobile station, the phase is added to the received signal by the phase shifter 1702 in FIG. The input signal is uncompressed in time, converted into a spread signal sequence, and output from the iterative combining unit 1704. Despreading is performed by multiplying this signal by a predetermined spreading code in the despreading section 1706. Thereafter, further processing is performed by the elements already described.

  The radio frequency waveform and chip rate of the signal transmitted by the VSCRF-CDMA system employed in the uplink are the same as those of the W-CDMA system. This is because the repetitive processing performed in the VSCRF-CDMA method rearranges the data order but does not change the chip rate. Therefore, for the uplink, the first and second communication systems can be easily coexisted by adopting the VSCRF-CDMA system in the second communication system.

It is a figure which shows a frequency band. 1 shows an overall view of a transmitter according to an embodiment of the present invention. It is a figure which shows the detail of the 1st and 2nd baseband process part by one Example of this invention. It is a figure which shows the frequency spectrum of the signal used with the 1st, 2nd communication system. Fig. 4 shows a conceptual diagram of a packet transmitted by the transmitter of Figs. It is a figure which shows another aspect which transmits a packet. It is a figure which shows the detail of the 1st and 2nd baseband process part by one Example of this invention. The conceptual diagram of the packet transmitted from the transmitter by a present Example is shown. It is a figure which shows the detail of the baseband process part by one Example of this invention. 10 shows a transmitter in which the processing elements are made more common than the baseband processing unit shown in FIG. 1 shows an overall view of a receiver according to an embodiment of the present invention. The detail of the 1st baseband process part of FIG. 11 is shown. The detail of the 2nd baseband process part of FIG. 11 is shown. 2 shows a baseband processing unit of a receiver according to an embodiment of the present invention. The block diagram of the spreading | diffusion part used for the transmitter of a VSCRF-CDMA system is shown. The block diagram of the de-spreading part used for the receiver of a VSCRC-CDMA system is shown. It is explanatory drawing regarding main operation | movement with a VSCRF-CDMA system.

Explanation of symbols

201, 202 First and second baseband processing units; 204 multiplexing unit; 206 RF transmission unit; 210 digital-analog conversion unit; 212 quadrature modulator; 214 local oscillator; 216 band-pass filter; 218 mixer; Bandpass filter; 224 power amplifier;
302 convolutional encoder; 304 data modulation unit; 306, 308 spreading unit; 310 multiplexing unit; 312 band limiting filter; 322 turbo encoder; 324 data modulator; 326 spreading unit; 330 multiplexing unit; 334 transmission TTI control unit; 342 turbo encoder; 344 data modulator; 345 interleaver; 347 serial parallel conversion unit; 349 spreading unit; 350 high-speed inverse Fourier transform unit; 352 guard interval insertion unit; 354 transmission TTI control unit;
362 convolutional encoder 364 data modulator 365 interleaver 365; 367 serial-parallel conversion unit; 369 spreading unit multiplexing unit 348;
902 interleaver; 904 fast Fourier transform unit; 906 band limiting filter;
1102 RF receiving unit; 1111, 1112 first and second baseband processing units; 1103 low noise amplifier; 1104 mixer; 1105 local oscillator; 1106 bandpass filter; 1107 automatic gain control unit; 1108 quadrature detector; 1109 local oscillator 1110 analog-digital converter;
1202 Band limiting filter; 1204 path searcher; 1206 despreading unit; 1208 channel estimation unit; 1210 rake combining unit 1210; 1212 combining unit; 1214 turbo decoder;
1302 Symbol timing detection unit; 1304 Guard interval removal unit; 1306 Fast Fourier transform unit; 1308 Demultiplexer; 1310 Channel estimation unit; 1312 Despreading unit; 1314 Parallel-serial conversion unit; 1316 Despreading unit; Deinterleaver; 1322 turbo encoder; 1324 Viterbi decoder;
1402 Demultiplexer; 1403 Band limiting filter; 1404 Fast inverse Fourier transform unit; 1406 Deinterleaver;
1602 Spreading unit; 1612, 1614 Multiplying unit; 1604 Repetitive combining unit; 1606 Phase shift unit;
1702 Phase shift part; 1704 Iterative synthesis part; 1706 Despreading part;
1802 Data sequence before compression; 1804 Compressed and repeated data sequence; 1806 Uplink frequency spectrum for all mobile stations

Claims (10)

A transmission apparatus that can be used in a first communication system of a single carrier scheme and a second communication system of a multicarrier scheme,
First retransmission means for transmitting a single carrier packet on a downlink channel, and retransmitting the single carrier packet in response to a request after the first retransmission standby period has elapsed;
Second retransmission means for transmitting a multicarrier packet on a downlink channel and retransmitting the multicarrier packet in response to a request after the second retransmission waiting period has elapsed;
And the second retransmission means transmits one or more multi-carrier packets during the first retransmission waiting period. The transmission apparatus according to claim 1, wherein a transmission time interval of one single carrier packet is equal to a transmission time interval of a plurality of multicarrier packets. The transmission device according to claim 2, wherein one single carrier packet and a plurality of multicarrier packets are alternately transmitted. The transmission apparatus according to claim 1, wherein the control channel of the first communication system is shared by the first and second communication systems. The transmission apparatus according to claim 4, wherein the control channel is transmitted continuously in time. The transmission apparatus according to claim 1, wherein the first control channel for the first communication system and the second control channel for the second communication system are transmitted separately. The transmission apparatus according to claim 6, wherein the first control channel is transmitted together with a single carrier packet, and the second control channel is transmitted together with a multicarrier packet. Means for Fourier transforming a signal representing a single carrier packet;
Filter means for band limiting the signal after Fourier transform;
Means for time-multiplexing the band-limited signal and the signal representing the multi-carrier packet;
Means for inverse Fourier transforming the time multiplexed signal;
The transmission apparatus according to claim 1, further comprising: The transmission apparatus according to claim 8, further comprising an encoding unit that selects and encodes one of signals representing a single carrier or multicarrier packet. A transmission apparatus that can be used in the first communication system of the single carrier system and the second communication system of the multi carrier system,
A single carrier packet is transmitted, and after the first retransmission waiting period has elapsed, the single carrier packet is retransmitted upon request,
A multi-carrier packet is transmitted, and after the second retransmission waiting period has elapsed, the multi-carrier packet is retransmitted upon request, and one or more multi-carrier packets are transmitted during the first retransmission waiting period. In case,
A receiving device for receiving the transmitted signal,
Means for Fourier transforming the received signal;
Means for temporally separating the signal after Fourier transform into a signal representing a single carrier packet and a signal representing a multicarrier packet;
Means for inverse Fourier transforming a signal representing a single carrier packet;
A receiving apparatus comprising:

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