JP4490999B2 - Wireless transmission apparatus and wireless transmission method - Google Patents

Description

  The present invention relates to a wireless transmission device and a wireless transmission method used in a digital wireless communication system.

  Conventionally, in a digital wireless communication system adopting a multicarrier communication system, communication is performed using a data channel for transmitting voice data and / or image data, and a control channel for controlling a partner communication station or a communication state. When performing, for the purpose of suppressing the power consumption of the mobile station, a method of allocating a minority subcarrier to the control channel and allocating a majority subcarrier to the data channel has been considered (for example, see Patent Documents 1 and 2).

In this method, the receiving apparatus performs A / D conversion on the control channel at a relatively low sampling rate for the purpose of receiving a narrow-band control channel composed of a small number of subcarriers, and responds to reception of the control channel. Thus, the sampling rate of the A / D conversion for the received signal is set high so that the wideband data channel composed of a large number of subcarriers can be received.
JP 2001-274767 A JP 2001-285927 A

  However, in such a conventional receiving apparatus, as shown in FIG. 12, the center frequency of the data channel composed of a plurality of subcarriers 2 and the center frequency of the control channel 6 are different. Thus, in order to switch reception from the control channel 6 to the data channel 4, it is necessary to change the frequency of the local signal for down-converting the subcarrier of the control channel 6.

  Incidentally, the local signal is for setting the center frequency of the transmission frequency band on the transmission side, multiplying the transmission signal after D / A conversion, and up-converting the transmission signal. On the receiving side, the received signal is down-converted by multiplying the signal received via the antenna by the local signal.

  Therefore, if the center frequency of the control channel 6 and the center frequency of the subcarrier group of the data channel 4 are different, the frequency of the local signal is changed to the center frequency of the data channel 4 after receiving the control channel 6. Then, the data channel 4 needs to be received, and until the PLL (Phase Locked Loop) circuit that generates the local signal is stabilized, the data channel is changed from the control channel 6 to the data channel. It is difficult to switch the reception to 4, which hinders the speeding up of switching between the control channel 6 and the data channel 4.

The radio transmitting apparatus according to the first aspect of the present invention arranges a control channel on a first plurality of subcarriers, and arranges a data channel on a frequency axis by a second plurality of both sides of the first plurality of subcarriers. Arrangement means for arranging the subcarriers, multiplication means for multiplying a multicarrier signal composed of the first plurality of subcarriers and the second plurality of subcarriers by a carrier signal, and the multicarrier after the carrier signal multiplication And a transmission means for transmitting a signal.

The radio transmitting apparatus according to the second aspect of the present invention arranges a data channel on a first plurality of subcarriers, and sets a control channel on the frequency axis more than the first plurality of subcarriers. a placement means for placing said second plurality of sub-carriers near the center frequency of one of the plurality of sub-carrier multi-carrier signal comprising a second plurality of subcarriers, a career signal to said multicarrier signal Multiplying means for multiplying and transmitting means for transmitting the multicarrier signal multiplied by the carrier signal, wherein the first plurality of subcarriers are symmetrical on the frequency axis around the center frequency of the multicarrier signal. And the second plurality of subcarriers are arranged symmetrically on the frequency axis around the center frequency of the multicarrier signal.

  According to the present invention, in a multi-cell environment, in a state where a plurality of base stations are simultaneously transmitting a control channel and a data channel, it is possible to operate while shifting the center frequency of the transmission frequency band of each mobile station for each cell. . This makes it possible to use the same frequency as the local signal multiplied to the control channel and the data channel while using the control channel at a different frequency between cells, and to switch the reception between the control channel and the data channel at high speed. It can be performed.

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

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of radio transmitting apparatus 10 according to Embodiment 1 of the present invention.

  In FIG. 1, a wireless transmission device 10 is provided in a base station device or a mobile station device and multiplexes and transmits a control channel signal and a data channel signal. In this embodiment, 5 [GHz] is transmitted. A case where a signal is transmitted using a bandwidth of 100 [MHz] in the frequency band as the center frequency will be described.

  In the wireless transmission device 10, a bandwidth of 1 [MHz] is used as a control channel, and a bandwidth of 99 [MHz] that is not used as a control channel out of a bandwidth of 100 [MHz] as a data channel Use width.

  The control channel signal is spread by the spreader 11, subjected to modulation processing by a predetermined modulation method in the modulator 12, and then supplied to the multiplexer 14. At the same time, the data channel signal is subjected to modulation processing in the modulation unit 13 and then supplied to the multiplexing unit 14.

  The multiplexing unit 14 multiplexes the control channel signal and the data channel signal so that the control channel signal is mapped to the center frequency of the transmission band with respect to the modulated control channel signal and the data channel signal.

  The output of the multiplexing unit 14 is supplied to a serial / parallel conversion unit (S / P) 15 and subjected to serial / parallel conversion, and then subjected to inverse fast Fourier transform processing in an IFFT (Inverse Fast Fourier Transform) unit 16. The result of the inverse fast Fourier transform processing is a bandwidth of 100 [MHz].

  The output of the IFFT unit 16 is converted into an analog signal by the digital analog (D / A) conversion unit 17 and then multiplied by a local signal (carrier signal) in the multiplication unit 18. Since the local signal is set to the center frequency (5 [GHz]) of the band used for transmission, the signal resulting from the multiplication of the local signal in the multiplier 18 is the transmission band (5 [GHz] ± 50). [MHz]) is up-converted and amplified by the amplification unit (AMP) 19 and then transmitted via the antenna 21.

  Thus, the multicarrier signal generated in the wireless transmission device 10 is configured such that the number of subcarriers 32 constituting the control channel 34 is smaller than the number of subcarriers 31 constituting the data channel 33 as shown in FIG. In addition, the control channel 34 is arranged at the center frequency fc of the transmission band (FFT range) of the data channel 33.

  In this way, by arranging the control channel 34 at the center frequency fc of the data channel 33, it becomes possible to use a common local frequency at the time of down-conversion on the receiving apparatus side described later.

  FIG. 3 is a block diagram illustrating a configuration of a wireless reception device 40 provided in the mobile station device or the base station device. In FIG. 3, the transmission signal from the wireless transmission device 10 received via the antenna 41 is amplified by the amplification unit 42 and then supplied to the multiplication unit 43. The multiplication unit 43 performs mixing processing by multiplying the signal supplied from the amplification unit 42 by a local signal set to 5 [GHz] which is the center frequency. As a result, the signal input to the multiplier 43 is down-converted.

  The channel selection unit 46 controls the band pass filter 44 so as to pass the 1 [MHz] band in accordance with the control channel 34 of the received signal, thereby passing only the control channel 34 of the received signal. In this case, the channel selection unit 46 controls the analog / digital (A / D) conversion unit 45 to sample the control channel 34 at a sampling rate of 1 [Msps] that matches the bandwidth of the control channel 34. To do.

  Further, the channel selection unit 46 controls the band pass filter 44 to pass the 100 [MHz] band according to the data channel 33 of the received signal, thereby passing the data channel 33 included in the received signal. . In this case, the channel selection unit 46 controls the analog digital (A / D) conversion unit 45 to perform sampling of the data channel 33 at a sampling rate of 100 [Msps] according to the bandwidth of the data channel 33. To do.

  When selecting the data channel 33, the switch unit 47 supplies the signal of the data channel 33 to an FFT (Fast Fourier Transform) unit 48 by switching to the first switching output end side. The signal of the data channel 33 supplied to the FFT unit 48 is subjected to fast Fourier transform processing, then supplied to the parallel serial (P / S) unit 49, converted into a serial signal, and then demodulated in the demodulation unit 51. Is done.

  On the other hand, when selecting the control channel 34, the switch unit 47 supplies the signal of the control channel 34 to the demodulation unit 50 by switching to the second switching output end side. The signal of the control channel 34 demodulated by the demodulator 50 is despread by the despreader 52.

  Thus, the multicarrier signal transmitted from the wireless transmission device 10 (FIG. 1) is received by the wireless reception device 40 (FIG. 3), and the control channel 34 arranged at the center frequency fc of the transmission band (data channel 33). And the data channel 33 are down-converted by a common local frequency.

  In this way, by down-converting the control channel 34 and the data channel 33 at a common local frequency, as shown in FIG. 4, at the time of switching between reception of the control channel 34 and reception of the data channel 33, There is no need to change the local frequency. In this way, it is possible to increase the speed of the switching operation of reception from the control channel 34 to the data channel 33 because it is no longer necessary to change the local signal frequency. In addition, by changing the sampling rate of one analog-to-digital conversion unit 45 to correspond to the control channel 34 and the data channel 33, compared to the case where an analog-to-digital conversion unit corresponding to each of the control channel 34 and the data channel 33 is provided. The circuit configuration can be further reduced.

  Also, by spreading and transmitting the signal of the control channel 34 in the wireless transmission device 10, it is possible to extract a signal addressed to the own station even if the same frequency as that of a nearby wireless transmission device is used.

  The center frequency of the transmission band is affected by a DC (Direct Current) offset. In this embodiment, the influence of the DC offset is achieved by spreading the control channel 34 arranged at the center frequency. Therefore, the radio receiver 40 can receive the data of the control channel 34 with high quality.

  In addition, by using only one subcarrier 32 as the control channel 34 in the wireless transmission device 10 and the wireless reception device 40, the wireless reception device 40 performs filter design without considering intersubcarrier interference. Therefore, the circuit configuration of the filter can be simplified.

(Embodiment 2)
FIG. 5 is a block diagram showing a configuration of radio transmitting apparatus 60 according to Embodiment 2 of the present invention.

  In FIG. 5, a wireless transmission device 60 is provided in a base station device or a mobile station device, and represents information indicating a modulation scheme and a coding scheme in packet transmission (hereinafter referred to as MCS (Modulation and Coding Schemes information)). A signal to be notified (MCS signal) is multiplexed with packet data and transmitted as a control channel. In this embodiment, a bandwidth of 100 [MHz] in a frequency band having a center frequency of 5 [GHz] A case where a signal is transmitted by using will be described.

  In the wireless transmission device 60, a bandwidth of 1 [MHz] is used as the MCS signal, and 99 [MHz] which is not used for transmission of the MCS signal out of the bandwidth of 100 [MHz] as the packet data. ] Bandwidth.

  The MCS signal is spread by the spreading unit 61, modulated by a modulation unit 63 using a predetermined modulation method, and then supplied to the multiplexing unit 65. At the same time, the data channel signal is encoded by the encoding unit 62 and supplied to the modulation unit 64 as packet data. The packet data is subjected to modulation processing by the modulation unit 64 and then supplied to the multiplexing unit 65.

  The multiplexing unit 65 multiplexes the MCS signal and the packet data with respect to the modulated MCS signal and the packet data so that the MCS signal is mapped to the center frequency of the transmission band.

  The output of the multiplexing unit 65 is supplied to a serial / parallel conversion unit (S / P) 66 and subjected to serial / parallel conversion, and then subjected to inverse fast Fourier transform processing in an IFFT (Inverse Fast Fourier Transform) unit 67. The result of the inverse fast Fourier transform processing is a bandwidth of 100 [MHz].

  The output of the IFFT unit 67 is converted into an analog signal by a digital / analog (D / A) conversion unit 68 and then multiplied by a local signal (carrier signal) in a multiplication unit 69. Since the local signal is set to the center frequency (5 [GHz]) of the band used for transmission, the signal resulting from the multiplication of the local signal in the multiplier 69 is the transmission band (5 [GHz] ± 50). [MHz]) is up-converted, amplified by an amplification unit (AMP) 70, and then transmitted via an antenna 71.

  Thus, as shown in FIG. 6 (A), the multicarrier signal generated in the wireless transmission device 60 is the packet data 95 in which the MCS signal 96, which is a control channel signal, is arranged at the center frequency, followed by the MCS signal 96. Will be sent.

  As described above, by arranging the MCS signal 96 at the center frequency of the packet data 95, it is possible to use a common local frequency at the time of down-conversion on the receiving apparatus side described later.

  FIG. 7 is a block diagram illustrating a configuration of a wireless reception device 80 provided in the mobile station device or the base station device. In FIG. 7, the transmission signal from the wireless transmission device 60 received via the antenna 81 is amplified by the amplification unit 82 and then supplied to the multiplication unit 94. The multiplication unit 94 performs mixing processing by multiplying the signal supplied from the amplification unit 82 by a local signal set to 5 [GHz] which is the center frequency. As a result, the signal input to the multiplier 94 is down-converted.

  The channel selection unit 85 receives only the MCS signal of the reception signal by controlling the band pass filter 83 so as to pass the band of 1 [MHz] in accordance with the MCS signal 96 of the reception signal in the normal time. The MCS signal is monitored as possible. In this case, the channel selection unit 85 controls the analog / digital (A / D) conversion unit 84 to sample the MCS signal 96 at a sampling rate of 1 [Msps] according to the bandwidth of the MCS signal 96. To do.

  When the MCS signal 96 is received, the MCS signal 96 is supplied to the demodulating unit 88 via the switch unit 86, and after being demodulated here, the despreading unit 90 performs the despreading process, This is supplied to the MCS decoding unit 93. The MCS signal 96 includes information on whether or not the packet data addressed to the wireless reception device 80 is transmitted in the next slot, and information on the modulation scheme and coding rate. By decoding these pieces of information included in the signal 96, the channel selection unit 85 selects information for controlling the bandwidth of the bandpass filter 83 and the sampling rate of the analog / digital conversion unit 84 for selecting packet data. Is supplied to the demodulator 91 for demodulating the packet data, and information indicating the demodulation method read from the MCS signal 96 is read from the MCS signal 96. Information representing the coding rate is supplied. As a result, the band pass filter 83 and the analog / digital conversion unit 84 perform band pass and digital conversion processing according to the incoming packet data, and further demodulates the data by a method determined by the demodulation unit 91, and the error correction unit 92 performs MCS. Error correction processing can be performed while controlling the coding rate determined by the information.

  For example, when it is predicted that packet data will be received in the next slot by decoding the MCS signal 96, the bandpass filter 83 passes the band of 100 [MHz] in accordance with the packet data 95. The packet data 95 included in the received signal is allowed to pass through. In this case, the channel selection unit 85 controls the analog / digital (A / D) conversion unit 84 to sample the packet data 95 at a sampling rate of 100 [Msps] according to the bandwidth of the packet data 95. To do.

  When the received signal is the packet data 95 by switching the switching output end according to the reception schedule of the packet data 95 decoded by the MCS decoding unit 93, the switch unit 86 sends the received data to the FFT (Fast Fourier Transform) unit 87. Supply. The packet data 95 supplied to the FFT unit 87 is subjected to a fast Fourier transform process, then supplied to a parallel serial (P / S) unit 89, converted into a serial signal, and demodulated by the demodulation unit 91. In this demodulation processing, the demodulation method is determined based on the information decoded from the MCS signal 96 by the MCS decoding unit 93.

  The packet data 95 demodulated by the demodulation unit 91 is subjected to error correction processing by the error correction unit 92. In this error correction process, the coding rate is controlled based on the information decoded from the MCS signal 96 by the MCS decoding unit 93, and finally the packet data is extracted.

  In this way, the MCS decoding unit 93 decodes the MCS information included in the MCS signal 96, so that adaptive reception according to the reception schedule, modulation method, and the like of the packet data 95 received after the MCS signal 96 is performed. Processing can be performed.

  Therefore, in the normal state, the radio reception device 80 only needs to monitor whether the MCS signal 96 is received in a state where only the MCS signal 96 having a narrow bandwidth can be received. The sampling rate of 84 can be lowered, and the power consumption can be reduced. Incidentally, FIG. 6B shows a case where the bandwidth of the MCS signal 102 transmitted before the packet data 101 is equivalent to that of the packet data 101. As can be seen from FIG. 6B. Since the bandwidth of the MCS signal 102 is wide, the sampling rate of the analog-digital conversion unit of the wireless reception device can be lowered.

  Further, by transmitting the MCS signal 96 including the modulation method and encoding method of the packet data 95, it is possible to notify the wireless reception device 80 of such information only immediately before the packet data 96 is transmitted. Therefore, the power consumption of the wireless receiving device 80 can be reduced.

(Other embodiments)
In the above embodiment, the case where the data channel 33 and the control channel 34 are arranged close to each other as shown in FIG. 2 has been described. However, the present invention is not limited to this, and as shown in FIG. For example, the guard frequency bands 111 and 112 may be provided between the control channel 34 and the data channel 33 by controlling the IFFT unit 16 (FIG. 1). In this way, the pass band width of the bandpass filter 44 (FIG. 3) can be widened, and the circuit scale of the filter configuration can be reduced accordingly.

  In the above-described embodiment, as shown in FIG. 8, the case where the guard frequency bands 111 and 112 between the control channel 34 and the data channel 33 are set to the same width has been described. Not limited to this, as shown in FIGS. 9A and 9B, the guard frequency bands 121 (131) and 122 (132) may have different widths. In this way, in a multi-cell environment, when a plurality of base stations as radio transmission apparatuses are simultaneously transmitting the control channel 34 and the data channel 33, the transmission frequencies of the plurality of mobile stations that are radio reception apparatuses. The center frequency fc of the band is shifted and operated for each cell like the center frequencies fc1 and fc2, so that the control channel 34 is used at a different frequency between the cells (the control channel 34 is FDMA (Frequency Division Multiple Access). As a configuration, the local signals of the control channel 34 and the data channel 33 can use the same frequency.

  Then, by changing the size (width) of the guard frequency by controlling, for example, the IFFT unit 16, the arrangement of the control channels 34 can be adaptively changed according to the situation of neighboring cells in a multi-cell environment. As a result, the interference of the control channel 34 can be reduced. In this case, in the case where the wireless transmission device 10 is a mobile station, the wireless transmission device 10 actually measures information related to neighboring cells from the received signal, and uses the measurement result to change the guard frequency width. The guard frequency can be controlled based on the information measured in (1).

  In the above-described embodiment, the case where only one subcarrier 32 is used as the control channel 34 has been described. However, the present invention is not limited to this. For example, as shown in FIG. You may make it use. In this way, each mobile station, which is a radio reception apparatus, can extract and receive only the necessary control channel.

  Further, as shown in FIG. 11, by performing the Nyquist filter processing by the Nyquist filter 141 on the control channel 34 and transmitting it, interference with other subcarriers (data channel subcarriers 31) can be suppressed, In addition, also on the wireless receiving device side, by using the Nyquist filter, it is possible to receive while suppressing intersymbol interference, and it is possible to improve reception performance.

  In addition, by applying a paging channel indicating that there is an incoming call as the control channel 34, the sampling rate of the analog-to-digital conversion unit on the wireless receiver side can be lowered when a call is not being made. Therefore, the power consumption of the wireless receiver can be reduced.

1 is a block diagram showing a configuration of a wireless transmission device according to Embodiment 1 of the present invention. Signal waveform diagram showing a transmission signal according to the first embodiment FIG. 2 is a block diagram showing a configuration of a radio reception apparatus according to Embodiment 1 of the present invention. Schematic diagram for explaining the operation of the first embodiment of the present invention The block diagram which shows the structure of the radio | wireless transmitter which concerns on Embodiment 2 of this invention. Schematic diagram for explaining the operation of the second embodiment of the present invention The block diagram which shows the structure of the radio | wireless receiver which concerns on Embodiment 2 of this invention. Signal waveform diagram for explanation of another embodiment Signal waveform diagram for explanation of another embodiment Signal waveform diagram for explanation of another embodiment Signal waveform diagram for explanation of another embodiment Signal waveform diagram for explanation of conventional operation Outline diagram for explanation of conventional operation

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,60 Wireless transmitter 11 Spreading unit 14,65 Multiplexing unit 16,67 IFFT unit 18,43,69,94 Multiplying unit 44,83 Band pass filter 45,84 Analog / digital conversion unit 48,87 FFT unit 52,90 Despreading unit 93 MCS decoding unit

Claims (6)

Placing data channels on the first plurality of subcarriers;
The control channel is located closer to the center frequency of the multicarrier signal composed of the first plurality of subcarriers and the second plurality of subcarriers on the frequency axis than the first plurality of subcarriers. Disposing means for disposing on two subcarriers;
And multiplying means for multiplying a career signal to said multicarrier signal,
Transmitting means for transmitting the multicarrier signal after the carrier signal multiplication,
The first plurality of subcarriers are arranged symmetrically on a frequency axis with a center frequency of the multicarrier signal as a center, and the second plurality of subcarriers has a frequency with a center frequency of the multicarrier signal as a center. Arranged symmetrically on the axis,
Wireless transmission device. A guard frequency band is provided between the first plurality of subcarriers and the second plurality of subcarriers;
The wireless transmission device according to claim 1 . Claim 1 or the base station apparatus comprising the radio transmitting apparatus according to claim 2, wherein. Claim 1 or the mobile station apparatus comprising the radio transmitting apparatus according to claim 2, wherein. Placing data channels on the first plurality of subcarriers;
The control channel is located closer to the center frequency of the multicarrier signal composed of the first plurality of subcarriers and the second plurality of subcarriers on the frequency axis than the first plurality of subcarriers. An arrangement step of arranging on two subcarriers;
A multiplication step of multiplying a career signal to said multicarrier signal,
A transmission step of transmitting a multicarrier signal after multiplication of the carrier signal, wherein the first plurality of subcarriers are symmetrically arranged on a frequency axis around a center frequency of the multicarrier signal, and The second subcarriers are arranged symmetrically on the frequency axis around the center frequency of the multicarrier signal.
Wireless transmission method. A guard frequency band is provided between the first plurality of subcarriers and the second plurality of subcarriers;
The wireless transmission method according to claim 5 .

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