JP2000115834A - Communication method, base station device and communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct transmission processing with high efficiency by utilizing a reserved frequency band efficiently when adopting a transmission system where a multi-carrier signal is transmitted in two-ways. SOLUTION: Broadband channels CH1-CH4, through which multi-carrier signals distributing data to m-sets (m is an integer of 2 or over) of subcarriers are transmitted in a reserved transmission band, and narrow band channels CH5, CH6 through which multi-carrier signals or single carrier signals using j-sets (j is an integer smaller than m) of subcarriers only are transmitted are used for a communication method. Then the communication of an outgoing channel from the base station to the communication terminal is conducted by using the broadband channel, and communication of an incoming channel is conducted by using the narrowband channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication method suitable for, for example, data communication in a mobile body, and a base station apparatus and a communication terminal apparatus to which the communication method is applied, and more particularly, to wireless transmission of a multicarrier signal. Related to technology.

[0002]

2. Description of the Related Art Conventionally, a multimedia mobile access system (MMAC: Multimedia Mobile) has been known.
A data communication system for mobile communication called Access System has been proposed. This access system is a high-speed wireless access system that can be seamlessly connected to an optical fiber network (BISDN). A relatively high frequency band such as 5 GHz is used as a frequency band, a transmission rate is about 30 Mbps, and an access method is used. Uses the TDMA / TDD method (time division multiple access method). FIG. 13 is a diagram showing an example of the overall configuration of the multimedia mobile access system. In this example, an IP (Internet) connected to the Internet is used.
This is a configuration for performing a service called "t Protocol" connection, and communication is performed with various content servers 11 connected to the Internet network 12 via the ISDN (or general telephone line) 13 or the optical fiber network 14. An MMAC base station 15 is provided. This base station 15
Predefined user network interface (UNI)
Is connected to the ISDN 13 or the optical fiber network 14.

[0003] The MMAC base station 15 performs wireless communication with the portable information terminal 16 by the above-described transmission method, and the base station 1
The base station 15 relays the communication between the terminals 16 and the lines 13 and 14 connected to the terminal 5.

FIG. 14 is a diagram showing a configuration of a conventionally proposed MMAC base station. In this case, an asynchronous transfer mode (A
syncronus Transfer Mode:
An optical fiber network 1 in which communication is performed by an ATM
4 is connected as an example, and the base station 1
Reference numeral 5 denotes an interface unit 15a for performing user network interface (UNI) with data (ATM cells) transmitted by ATM, which is connected to the optical fiber network 14, and multiplexes ATM cells. The ATM network line control unit 15b connected to the interface unit 15a performs line control such as call connection with the network. ATM cell disassembly / assembly unit 15 connected to ATM network control unit 15b
In c, the ATM cells are disassembled from the network side and the ATM cells to be transmitted to the network side are assembled.

[0005] The received data from the network decomposed by the ATM cell decomposing / assembling unit 15c is sent to the MMAC channel coding / decoding unit 15d, where it is converted into an MMAC radio transmission format, and the converted data is modulated. After being subjected to modulation processing by QPSK modulation or the like by the unit 15g, transmission processing such as frequency conversion or amplification is performed by the transmission unit 15h, and wireless transmission is performed from the antenna 15i to the terminal.

A signal transmitted from the terminal side is subjected to reception processing such as frequency conversion in a reception unit 15j connected to an antenna 15i, and then demodulated in a demodulation unit 15k to demodulate received data. The received data is supplied to the MMAC channel coding / decoding unit 15d to perform a decoding process. Then, it is assembled as an ATM cell by the ATM cell disassembly / assembly unit 15c,
Optical fiber network 1 connected under the control of network line controller 15b
4 from the interface unit 15a.

[0007] These processes in the MMAC base station 15 are performed by the central control unit (CPU) 15e from the bus line 1.
This is executed under the control via 5f.

[0008] As shown in Fig. 15, a portable information terminal 16 which is an MMAC terminal has a receiving section 16b connected to an antenna 16a and performs a receiving process such as frequency conversion and then a demodulating section 16c. Data demodulation is performed,
The demodulated received data is supplied to the MMAC channel coding / decoding unit 16d to perform a conversion process from the MMAC wireless transmission format. The converted data is stored in the central control unit (CPU) of the terminal 16.
The video signal is supplied to a digital signal processing unit (DSP) 16k, where the video data and the audio data are separated and subjected to a decoding process based on the MPEG-2 system. Is supplied to the liquid crystal driver 16i, and an image is displayed on the liquid crystal display 16j under the control of the central controller 16g. The audio data included in the received data is converted into an analog audio signal by the digital signal processing unit 16k and output from the speaker 16m.

The transmission data generated based on the operation of the operation unit 16h connected to the central control unit 16g is supplied to the MMAC channel coding / decoding unit 16d, and is converted into the MMAC wireless transmission format. After the converted data is modulated by the modulator 16e by QPSK modulation or the like, the transmitter 16
Transmission processing such as frequency conversion and amplification is performed at f, and the signal is wirelessly transmitted from the antenna 16a to the base station.

By preparing a base station and a terminal device as such an MMAC system and connecting them to the Internet or the like, the terminal device 16 can receive Internet broadcasts from various content servers. In this case, in the case of the MMAC system, high-speed wireless access is possible, so that the terminal device can also receive and display moving image data and the like.

Here, a signal transmitted by radio between the conventional MMAC base station 15 and the portable information terminal 16 will be described. In this system, an OFDM (Orthogonal Frequency) is used.
A multicarrier signal transmission method called an encyDivision Multiplex (orthogonal frequency division multiplex) method is applied to wireless transmission. That is, as a wireless transmission signal, a plurality of subcarriers (here, m subcarriers: m is a plurality, for example, 32
(A relatively large value such as, for example) are arranged, and the transmission data is dispersed and modulated on each subcarrier and transmitted.

A configuration for performing transmission processing and reception processing according to the OFDM method will be described below. FIG. 16 is a diagram showing the configuration of the portable information terminal 16. An antenna 101 for both transmission and reception is connected to a low-noise amplifier 103 via an antenna switch 102, and a received signal amplified by the low-noise amplifier 103 is transmitted. To the reception mixer 104, mixes the oscillation output fl1 of the first local oscillator 105 with the reception signal, and converts the reception signal in a predetermined frequency band into an intermediate frequency signal.

The intermediate frequency signal output from the receiving mixer 104 is supplied to a quadrature detector 106, and the second local oscillator 10
7 is mixed and subjected to quadrature detection, separated into an I component and a Q component, and the detected I component and Q component are supplied to an analog / digital converter 108, and the digital value of each component is supplied. Obtain data ID and QD. The data ID and QD are converted to a fast Fourier transform circuit (FFT).
Circuit) 109 to perform a discrete Fourier transform process at m points equal to the number of subcarriers to obtain parallel data of m symbols.

M output from the fast Fourier transform circuit 109
The parallel data of the symbol is supplied to a parallel-serial conversion circuit 11.
0 and supplied as one series of serial data, and the converted serial data is used as received data.

As a configuration of the transmission system, transmission data (serial data) is supplied to a serial-parallel conversion circuit 111,
The transmission data is converted into m parallel data. This m
The parallel data of the book is converted into an inverse Fourier transform circuit (IFFT).
Circuit) 112 to perform an inverse discrete Fourier transform of m points and obtain digital baseband data I on the orthogonal time axis.
-D and QD are obtained. This baseband data ID
And QD are supplied to the digital / analog converter 113 to obtain analog signals of the I component and the Q component.

The obtained I component and Q component signals are supplied to a quadrature modulator 114 and quadrature modulated based on the oscillation output fl2 of the second local oscillator 107. The signal orthogonally modulated by the quadrature modulator 114 is supplied to a transmission mixer 115,
The oscillation output fl1 of the first local oscillator 105 is mixed, frequency-converted into a signal in the transmission frequency band, the frequency-converted signal is amplified by the power amplifier 116, and then supplied to the antenna 101 via the antenna switch 102. , Wireless transmission.

The structure of a transmission signal processed in such a transmission system and a reception system will be described. In an MMAC system, transmission of data having a frame configuration as shown in FIG. 17 has been proposed. In one frame, a plurality of time slots are formed, and each of the one unit slot includes a header part, an information part, a CRC (error detection code).
Section and an FEC (error correction code) section are sequentially arranged. 1
A predetermined number of slots T1, T2,.
Tn (n is an arbitrary integer) is a slot of an uplink period and is a slot used for transmission from a terminal device to a base station. A predetermined number of slots R1, R2,... Rn (n is an arbitrary integer) in the latter half of one frame are slots for the downlink period and are slots used for transmission from the base station to the terminal device.

In each of the slots in the uplink period and the slots in the downlink period, transmission processing of a multicarrier signal having the same configuration with m carriers is performed.

[0019]

When the OFDM system is used for wireless transmission of a multicarrier signal as in the above-described MMAC system, the peak power ratio of the transmission power to the average power is considered. There was a problem that became large. For example, if the number of subcarriers is 32, a ratio of 10 log32 = 15 dB is simply obtained. Therefore, it is necessary to use a power amplifier having a wide linearity as a power amplifier in a transmission unit of a transmission device, and it is a small terminal device that requires low power consumption due to low power efficiency due to poor power efficiency. Transmitting the signal has a problem that the load is very large.

In addition, when wireless transmission of a multicarrier signal is performed by applying the OFDM method, a wide transmission bandwidth of one channel is required, and when a transmission system is constructed by allocating channels within the prepared transmission band. There was a problem that the consistency of the data was not good. For example, in the above-described MMAC system, the transmission bandwidth of one channel is 20 MHz.
It is assumed that if the prepared transmission bandwidth is a bandwidth of an integral multiple of 20 MHz, the channel arrangement can be performed without any problem. There are many cases where unused bands exist.

[0021] In view of the above, the present invention is designed to perform efficient transmission processing by using a prepared frequency band efficiently when a transmission system in which multicarrier signals are transmitted bidirectionally is applied. The purpose is to do.

[0022]

According to the communication method of the present invention, data can be transmitted as a multicarrier signal in which data is dispersed in m (m is an integer of 2 or more) subcarriers within a prepared transmission band. A wideband channel and a narrowband channel for transmitting as a multicarrier signal or a single carrier signal using only j (j is an integer smaller than m) subcarriers are set, and downlink communication from the base station to the communication terminal is performed. Is performed using a wideband channel, and uplink communication from the communication terminal to the base station is performed using a narrowband channel.

According to the present invention, the downlink from the base station to the communication terminal is transmitted as a multicarrier signal having a large number of subcarriers using a wideband channel, and the uplink from the communication terminal to the base station is transmitted in a narrow band. It is transmitted as a multicarrier signal with a small number of subcarriers (or a single carrier signal using one carrier) using a channel.

The base station apparatus according to the present invention further comprises a modulating means for modulating data to be transmitted to the communication terminal into a multicarrier signal in which data is dispersed on m (m is an integer of 2 or more) subcarriers. Transmitting means for transmitting a multicarrier signal modulated by the modulation means in a frequency band prepared as a wideband channel; receiving means for receiving a signal transmitted in a narrowband channel having a narrower bandwidth than the wideband channel; From the reception output of the receiving means, j (j is m
Demodulation means for demodulating data modulated on subcarriers of smaller integers).

According to the present invention, the signal to be transmitted to the communication terminal by the base station device is a multicarrier signal with a large number of subcarriers using a wideband channel, and the signal received by the base station device is narrow. It is processed as a multicarrier signal with a small number of subcarriers using a band channel (or a single carrier signal using one carrier).

Further, the communication terminal device of the present invention comprises a receiving means for receiving a signal transmitted in a frequency band prepared as a wideband channel, and m (m is an integer of 2 or more) m receiving outputs from the receiving means. Demodulation means for demodulating data dispersed and modulated on subcarriers; modulation means for converting data to be transmitted to the base station into data modulated on j (j is an integer smaller than m) subcarriers; Transmitting means for transmitting the output modulated by the means in a frequency band prepared as a narrow band channel.

According to the present invention, a signal received by the communication terminal device is processed as a multicarrier signal having a large number of subcarriers transmitted on a wideband channel, and a signal transmitted from the communication terminal device is processed by the number of subcarriers. A small number of multicarrier signals (or a single carrier signal by one carrier) are transmitted on a narrow band channel.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

In this embodiment, the present invention is applied to a system for performing wireless communication between a base station and a terminal device, for example, a multimedia mobile access system (hereinafter referred to as MMAC). This is an example in which communication is performed between the server and the server. The basic system configuration of the MMAC is the same as that of the MMAC described in the conventional example. As described with reference to FIG. 13, various data such as the Internet can be transferred to a portable information terminal via a base station. It is also possible to transmit data from a portable information terminal by receiving the data by a communication terminal device such as the above.

Here, the signal wirelessly transmitted between the MMAC base station of this example and the communication terminal device is basically OFD
It is a multicarrier signal called an M (Orthogonal Frequency Division Multiplex) system, and a signal transmitted from the base station to the communication terminal device on the downlink and from the communication terminal device to the base station on the uplink. In the transmitted signal, the state of the signal is changed. The details of the transmission signal will be described later.

First, processing in the communication terminal device of the present embodiment will be described. The overall configuration of the communication terminal device is the same as that of a conventional communication terminal device (for example, the MMAC terminal 16 shown in FIG. 15 in the conventional example), and the configuration for transmission processing in this example is different from the conventional one. FIG. 1 is a diagram showing a configuration of a receiving unit and a transmitting unit of a communication terminal device according to the present embodiment. An antenna 101 for both transmission and reception is connected to a low noise amplifier 103 via an antenna switch 102. the received signal amplified by the 103, and supplied to the reception mixer 104, and converts the mixed oscillation output fl1 of the first local oscillator 105 to the received signal, the reception signal in a predetermined frequency band f ₀ into an intermediate frequency signal .

The intermediate frequency signal output from the reception mixer 104 is supplied to the quadrature detector 106, and the second local oscillator 10
7 is mixed and subjected to quadrature detection, separated into an I component and a Q component, and the detected I component and Q component are supplied to an analog / digital converter 108, and the digital value of each component is supplied. Obtain data ID and QD. The data ID and QD are converted to a fast Fourier transform circuit (FFT).
Circuit) 109 to perform a discrete Fourier transform process at m points equal to the number of subcarriers to obtain parallel data of m symbols. Note that the number m of subcarriers is an integer value of 2 or more, and m is generally a relatively large value such as 32, for example.

M output from the fast Fourier transform circuit 109
The parallel data of the symbol is supplied to a parallel-serial conversion circuit 11.
0 to form a series of serial data, the converted serial data is used as reception data, and the obtained reception data is supplied to a data processing unit (not shown), and various data such as video display and audio reproduction are provided. Processing is performed. The configuration of the receiving system up to this point is the same as the configuration described with reference to FIG. 16 in the conventional example.

As a configuration of the transmission system, transmission data (serial data) is supplied to a serial-parallel conversion circuit 111,
The transmission data is converted into parallel data of two systems. These two sets of parallel data are transmitted to a baseband filter 12.
2 to remove unnecessary components to obtain orthogonal digital baseband data ID and QD on the time axis.
The baseband data ID and QD are supplied to the digital / analog converter 113 to obtain analog signals of the I component and the Q component.

The obtained I-component and Q-component signals are supplied to a quadrature modulator 114 and quadrature-modulated based on the oscillation output fl2 of the second local oscillator 107. The signal orthogonally modulated by the quadrature modulator 114 is supplied to a transmission mixer 115,
By mixing an oscillation output fl1 of the first local oscillator 105, and frequency converted into a signal of a transmission frequency band f _0, the frequency-converted signal was amplified by the power amplifier 116, to the antenna 101 through the antenna switch 102 Supply,
Radio transmission.

Next, a communication terminal device having the configuration shown in FIG.
The configuration of a transmission signal wirelessly transmitted to and from a base station will be described. FIG. 2 is a diagram showing an example of a transmission signal configuration according to the present embodiment, and here is configured to transmit data having a frame configuration. That is, one frame is defined every predetermined time, and a plurality of time slots are formed in one frame. The frame period is defined by, for example, a synchronization signal transmitted from the base station. In each one unit slot, a header part Ts ₁ , an information part Ts ₂ , and a CR
C (error detection code) part Ts ₃ , FEC (error correction code)
Signal section Ts ₄ are arranged in this order is transmitted. Maximum effective symbol number that can be transmitted in one slot of the information part Ts ₂ is here a k.

Here, the access method is TDMA /
When the same frequency (channel) is used for the uplink from the communication terminal device to the base station and for the downlink from the base station to the communication terminal device when the TDD scheme is applied and when a different frequency is used. In each case, different time slots in one frame are used in a time division manner in the uplink and the downlink. When different frequencies (channels) are used for the uplink and the downlink, channel switching is performed between an uplink time slot and a downlink time slot.

A predetermined number of slots T in the first half of one frame
1, T2, ΔTn (n is an arbitrary integer) is a slot of the uplink period Tu, and is a slot used for uplink transmission from the terminal device to the base station. A predetermined number of slots R1, R2,... R in the latter half of one frame
n (n is an arbitrary integer) is a slot of the downlink period Td and is a slot used for downlink transmission from the base station to the terminal device.

In any one of the slots T1 to Tn prepared in the uplink period Tu, a signal wirelessly transmitted from the communication terminal apparatus to the base station is transmitted by any one of the subcarriers (here, the endmost carrier). Only the subcarrier fm allocated to the section is transmitted, and uplink data is transmitted as a single carrier signal using only this subcarrier fm. In this case, the number of effective symbols transmitted in one slot is k / m. However, in the case of a communication terminal device having a configuration different from the configuration shown in FIG. 1 (for example, a communication terminal device having a configuration shown in FIG. 15 as a conventional example), a multicarrier signal composed of m subcarrier signals is transmitted in the uplink. May also be transmitted.

Slots R1 to R in downlink period Td
In n, a downlink signal wirelessly transmitted from the base station to the communication terminal device is a multicarrier signal having m carriers in any slot, and data having an effective symbol number k is transmitted.

FIG. 3 shows an example of a channel configuration in which the data having the frame configuration is wirelessly transmitted. Here, as a frequency band B ₀ usable in the system of this example, for example, 5G
It is assumed that a bandwidth of 100 MHz in the Hz band is prepared. In this frequency band B _0, 1 channel is about 20MH
four channels CH1, CH2, CH with a bandwidth of z
3, CH4 is arranged. These four channels CH1
CH4 is a high-speed accessible wideband channel provided with a band in which a multicarrier signal having m subcarriers can be transmitted. In addition, each channel CH1 to C
Although H4 bandwidth is about 20 MHz, in consideration of the interference to adjacent bands, where the frequency band B ₀ bandwidth 100MHz, the four wideband channels CH1~
The limitation is to arrange CH4. In this example, five wideband channels cannot be arranged.

Therefore, in this example, as shown in FIG. 3, guard band portions B ₁ and B ₂ narrower than the bandwidths of the wideband channels CH 1 to CH 4 are provided below and above the usable frequency band B _0. Exists. Here, in the present example, the wide band channel CH is added to both guard band portions B ₁ and B _2.
Narrowband channel CH having a narrower bandwidth than 1 to CH4
5, CH6 is arranged. This narrow band channel CH5
In CH6, the number of carriers of a signal to be transmitted is limited to j (j <m) due to the bandwidth, and the channel is a channel that can be accessed at a low speed limited to j carriers. Here, j is a signal of 1 (that is, a single carrier signal).

The narrow band channels CH5 and CH6 arranged in the guard band section are used for the uplink (uplink).
Use as a communication channel dedicated to low-speed access in
Therefore, in these narrow band channels CH5 and CH6,
Uplink period Tu in the first half of the frame configuration shown in FIG.
Only used for wireless transmission.

In the case of this embodiment, any one of the channels is used as a control channel for transmitting control information from the base station. Here, one of the wideband channels CH1 to CH4 is controlled. It is configured to be used as a channel. The channel CH1 used as the control channel is a broadband channel. When performing uplink communication on the channel CH1, a narrowband signal (low-speed access signal) having j carriers is transmitted. Sometimes it is done. When transmitting the uplink low-speed access signal on the channel CH1, for example, as shown in FIG. 3, only a part of the band CH1a in the band of the channel CH1 is used.

FIG. 4 is a diagram showing an example of the configuration of a base station that performs wireless communication with a communication terminal device in such a channel arrangement. The configuration will be described below. The transmitting / receiving antenna 201 is connected to a low-noise amplifier 203 via an antenna switch 202, and the received signal amplified by the low-noise amplifier 203 is received by the receiving mixer 20.
4 is supplied to and mixed with the oscillation output fl1 of the first local oscillator 205 to the received signal, converts the received signal in a predetermined frequency band f ₀ into an intermediate frequency signal.

The intermediate frequency signal output from the reception mixer 204 is supplied to the quadrature detector 206, and the second local oscillator 20
7 is mixed and subjected to quadrature detection to separate it into an I component and a Q component. The detected I component and Q component are supplied to an analog / digital converter 208, and the digital of each component is supplied. Obtain data ID and QD. The data ID and QD are converted to a fast Fourier transform circuit (FFT).
Circuit) 209 to perform discrete Fourier transform processing at m points equal to the maximum number of subcarriers, thereby obtaining parallel data of m symbols.

M output from the fast Fourier transform circuit 209
The parallel data of the symbol is converted to a parallel-serial conversion circuit 21.
, And supplies the converted serial data to the determination / selection circuit 211. Further, the digital data ID and QD output from the analog / digital converter 208 are directly supplied to another parallel-serial conversion circuit 212 to be converted into one series of serial data. It is supplied to the determination / selection circuit 211. The determination / selection circuit 211 performs a determination process on the data supplied from one of the conversion circuits 210 and the data supplied from the other conversion circuit 212, and determines which data is considered to be correct received data. It is determined whether there is any data, and the determined data is selected, output as reception data, and supplied to a reception data processing system (not shown) at a subsequent stage. The determination process in the determination / selection circuit 211 is performed using, for example, an error detection code added to each slot.

As a configuration of a transmission system in the base station, transmission data (serial data) is supplied to a serial-parallel conversion circuit 211, and the transmission data is converted into m parallel data. The m pieces of parallel data are supplied to an inverse Fourier transform circuit (IFFT circuit) 222 to perform m-point inverse discrete Fourier transform to obtain orthogonal digital baseband data ID and QD on the time axis. . The baseband data ID and QD are converted into a digital / analog converter 2
23 to obtain I and Q component analog signals.

The obtained signals of the I component and the Q component are supplied to a quadrature modulator 224, and are quadrature modulated based on the oscillation output fl2 of the second local oscillator 207. The signal orthogonally modulated by the orthogonal modulator 224 is supplied to a transmission mixer 225,
By mixing an oscillation output fl1 of the first local oscillator 205, and frequency converted into a signal of a transmission frequency band f _0, the frequency-converted signal was amplified by the power amplifier 226, to the antenna 201 via the antenna switch 202 Supply,
Wireless communication is performed to each communication terminal device.

An example of a control sequence for performing communication between the base station and the communication terminal device configured as described above will be described with reference to FIG. In FIG. 5, the left side is the communication terminal apparatus side, and the right side is the base station side, which can access a control channel (here, a predetermined slot in CH1) and a communication channel, respectively. In FIG.
Transmission of a signal indicated by a thick arrow is transmission using a high-speed access line using the number of carriers m, and transmission of a signal indicated by a thin arrow is transmission using a low-speed access line using a single carrier.

The base station intermittently broadcasts a control signal S1 for a perch in a standby state of each terminal device in a slot for a downlink control channel. The communication terminal receives the control signal S1 intermittently. By performing such intermittent reception during standby, for example, when the communication terminal device is a device driven by a built-in battery, the duration of the battery can be lengthened.

When there is a transmission request on the communication terminal side, a link channel establishment request signal S2 is transmitted in a slot for an uplink control channel. Here, when the terminal device requesting the transmission is a terminal device transmitting the uplink as a single carrier signal as shown in FIG. 1, the link channel establishment request signal S2 is a single carrier low-speed access line. (Slot) transmission. When the base station receives the link channel establishment request signal S2, whether the signal is a low-speed access (ie, transmission of a single carrier signal) or a high-speed access (ie, transmission of m multi-carrier signals) judge. As the determination process at this time, for example, the determination is performed based on a result of performing a demodulation process suitable for each system. Alternatively, if high-speed access and low-speed access are separated at the slot position,
Judge from the slot position. The details of the process of separating low-speed access and high-speed access at this slot position will be described later.

After this access determination, a vacant communication channel is notified by transmitting a link channel assignment signal S3. Here, it is determined that the uplink from the terminal device is for low-speed access, and therefore, a channel dedicated to low-speed access (channel C
An empty slot of H5 or CH6 (here, CH5) is designated, and as a downlink channel, an empty slot of a channel for high-speed access (any of channels CH1 to CH4: CH2 here) is designated.

In response to the notification of the communication channel, the communication terminal apparatus shifts to communication on the specified communication channel (slot), and performs single carrier communication on the corresponding slot of the specified uplink communication channel (CH5). The signal synchronization signal S4 is transmitted. At this time, since the base station knows whether the signal from the communication terminal is low-speed access or high-speed access (here, low-speed access), the signal can be demodulated, and the base station side also designates a downlink channel (CH2). The synchronization signal S5 of the multi-carrier signal is transmitted in the slot corresponding to, and the synchronization between them is established.

Thereafter, exchange of a call control signal S6 such as setting and acceptance of a connection destination is performed by both parties using the set communication channel, and the state shifts to a communication state for transmitting necessary data S7. Even in this communication state, the uplink is for low-speed access, and only the downlink is for high-speed access.
The example of FIG. 5 is an example in which the uplink from the communication terminal device is a low-speed access. However, when the uplink from the communication terminal device is a high-speed access, the control sequence is as follows. It merely changes to a high-speed access signal using an access channel.

In the channel CH1 used as a control channel, high-speed access and low-speed access are mixed in uplink communication. In such a case, for example, the uplink period Tu within one frame is used. the slot, as shown in FIG. 6 can be addressed by dividing the slot T _L of slots T _H and a low-speed access for high-speed access.

That is, as shown in FIG. 6, a predetermined number of slots (a slot T1 every three slots in this case) among a plurality of slots T1, T2,. , the T4 ‥‥) slow dedicated slot T _L, the remaining slots and high-speed dedicated slot T _H. Then, when a communication terminal apparatus configured to transmit a single carrier signal using only one subcarrier as an uplink, as in the configuration shown in FIG. 1, for example, transmits an uplink signal to a base station. Uses the low-speed dedicated slot _TL . Then, in the case of a communication terminal device having a configuration similar to the conventional one that transmits a multicarrier signal having m carriers as an uplink signal, the high-speed dedicated slot _TH is used.

On the base station side, when receiving an uplink signal, at the slot position set as the high-speed dedicated slot T _H , the m-point discrete Fourier transform circuit provided in the demodulation unit of the receiving system is used. A conversion process is performed to perform a demodulation process on a multicarrier signal having m carriers. Then, at the slot position set as the low-speed dedicated slot _TL , the high-speed Fourier transform circuit does not perform the discrete Fourier transform process, but demodulates only the received signal of one carrier.

As another configuration in which low-speed access and high-speed access are mixed in the uplink period Tu, for example, as shown in FIG. 7, a plurality of slots T1, T2,. In any slot,
Transmission of a single carrier signal from the communication terminal device of the present example and transmission of a multicarrier signal from a conventional communication terminal device may be made possible.

As shown in FIG. 7, when the system is configured such that each slot can transmit either a single carrier signal or a multi-carrier signal, the state of the signal received by the base station is determined. Configuration.

By performing communication in the above-described configuration, when the communication terminal device is configured to perform low-speed access on the uplink, the load on the transmission processing system hardware provided in the communication terminal device is reduced. And efficient transmission. In other words, when performing transmission processing of a multi-carrier signal, it is necessary to use a power amplifier having a wide linearity for the power amplifier of the transmission unit.
As the power amplifier 116 of the transmission unit of the communication terminal device shown in (1), it is only necessary to amplify a single carrier signal, an amplifier with high power efficiency that does not require wide linearity can be used, and the configuration of the communication terminal device is simplified. Can be Therefore, for example, when the communication terminal device is driven by a battery, the power required for the transmission process can be reduced, and the power consumption can be reduced (that is, the duration of the battery can be prolonged).

In this case, since the signal at the time of low-speed access on the uplink is a signal in a form in which a plurality of subcarriers constituting a multicarrier signal are thinned out, the base station side transmits the transmission signal at the time of high-speed access. The processing is not so much different from that at the time of reception (the degree to which fast Fourier transform etc. changes), the amount of information in the uplink is small, and the asymmetric wireless data communication system in which the downlink is fast without damaging the application , Can be realized efficiently.

When low-speed access is performed on the uplink as in this example, the amount of data that can be transmitted from the communication terminal apparatus to the base station decreases accordingly. However, in the case of a communication system such as MMAC to which this example is applied. In such a case, downlink transmission is data transmission such as Internet access, video server access, video-on-demand, and Internet broadcasting, which requires a large transmission capacity. These are data having a relatively small capacity such as data instructing execution of these accesses and e-mail data, and there is no inconvenience due to low-speed access to the uplink.

In this example, when low-speed access is performed on the uplink, data transmission is performed using the channels CH5 and CH6 prepared as narrow-band channels. Can be used well. That is, as shown in FIG. 3, the wideband channel in the available frequency band B ₀ CH1 to CH4
The use narrowband channel CH5, CH6 set the guard band portion which occurs when placed, is performed slower access in the uplink, data transmission with effective use of available frequency bands B ₀ is performed . Except for CH1 used as a control channel, low-speed access data transmission is not performed on a wideband channel, and data transmission that effectively utilizes a prepared band is also performed on a wideband channel.

[0065] In the embodiment described above, was placed in the guard band portion of the available frequency bands B ₀ narrowband channels, it is arranged narrowband channels to other frequency positions within the available frequency band good. Further, only one narrowband channel may be arranged.

Further, the prepared narrow band channel CH
The use of the downlink period in CH5 and CH6 is not described in the above embodiment, but may be used for any data transmission from the base station.

For example, one of the narrow band channels CH
5, CH6 may be prepared as a control channel for low-speed access, and a control channel different from the control channel for high-speed access may be set. Figure 8 is a diagram showing an example of a channel setting state in this case, wideband channels 4 channels in the available frequency band B ₀ CH1
~ CH4 and guard band sections B ₁ , B ₂
Narrowband channels CH5 and CH6 are allocated to the terminal device to which the uplink is accessed at a high speed, and control data is broadcast using the channel CH1 as a control channel, and the terminal device to which the uplink is accessed at a low speed. On the other hand, control data is broadcast using channel CH5 as a control channel.

An example of a control sequence for performing communication between the base station and the communication terminal when such a channel is set will be described with reference to FIG. In this example,
The communication terminal device is not only for the transmission system but also for the reception system.
A configuration that can perform processing (reception processing) of a low-speed access signal such as a single carrier signal is used.
In FIG. 9, the communication terminal device side is on the left side and the base station side is on the right side, so that a control channel (here, a predetermined slot in CH5) and a communication channel can be accessed. In FIG. 9, transmission of a signal indicated by a thick arrow is transmission using a high-speed access line using the number of carriers m, and transmission of a signal indicated by a thin arrow is transmission using a low-speed access line using a single carrier.

The base station intermittently broadcasts a control signal S11 for a perch at the time of standby of each terminal device in a slot for a downlink control channel. Here, the control signal S11 is a single carrier signal. The communication terminal receives the control signal S11 intermittently. In addition, a control channel for high-speed access (not shown)
At the same time, the control signal is intermittently notified by the multicarrier signal.

Then, when there is a transmission request on the communication terminal side, a link channel establishment request signal S12 is transmitted in the slot for the uplink control channel. here,
The link channel establishment request signal S12 is a low-speed access transmission using a single carrier. On the base station side,
When the link channel establishment request signal S12 is received, it is determined whether the signal is a low-speed access (ie, transmission of a single carrier signal) or a high-speed access (ie, transmission of m multi-carrier signals). In the determination processing at this time, since the requested channel is the channel CH5 for low-speed access, it is determined that the request at this time is low-speed access.

After this access determination, a vacant communication channel is notified by transmitting a link channel assignment signal S13. Here, since it is determined that the uplink from the terminal device is low-speed access, an empty slot of a channel dedicated to low-speed access (one of channels CH5 and CH6: CH5 here) is designated as the channel for the uplink. As the downlink channel, an empty slot of a channel for high-speed access (any of channels CH1 to CH4: CH2 in this case) is specified.

In response to the notification of the communication channel, the communication terminal apparatus shifts to communication on the specified communication channel (slot), and the base station transmits the communication on the corresponding slot of the corresponding downlink communication channel (CH2). A synchronization signal S14 of a single carrier signal is transmitted to establish synchronization between the base station and the communication terminal device. For the uplink,
Here, since there is no channel shift, there is no transmission of the synchronization signal. However, when the channel changes, it is necessary to similarly transmit the synchronization signal to establish synchronization.

Thereafter, exchange of the call control signal S15 such as setting and acceptance of a connection destination is performed by both parties using the set communication channel, and the state shifts to a communication state for transmitting necessary data S16. Even in this communication state, the uplink is for low-speed access, and only the downlink is for high-speed access.

By performing communication in this manner, access using a narrow band channel as a control channel becomes possible.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS.

In this example, as in the case of the first embodiment, the present invention is applied to a system for performing wireless communication between a base station and a terminal device, for example, MMAC.
This is an example in which communication is performed between a MAC base station and a terminal device. Here, the basic system configuration of the applied MMAC is the same system as the MMAC described in the conventional example, and as described with reference to FIG.
Various data from the Internet and the like are received by a communication terminal device such as a portable information terminal via a base station, and data can be transmitted from the portable information terminal.

The signals wirelessly transmitted between the MMAC base station of this example and the communication terminal apparatus are basically basically OFDM (Orthogonal Frequencies) as in the first embodiment.
Although it is a multicarrier signal called a quency division multiplex (orthogonal frequency division multiplex) system, it is transmitted from the base station to the communication terminal device on the downlink and transmitted from the communication terminal device to the base station on the uplink. At the traffic light,
The state of the signal has changed. The details of the transmission signal will be described later.

First, the configuration of the communication terminal of this embodiment will be described. The overall configuration of the communication terminal of this embodiment is the same as that of the conventional communication terminal (for example, the MMAC terminal 16 shown in FIG. 15 in the conventional example). In this example, the configuration for transmission processing is different from that in the related art. FIG. 10 is a diagram illustrating a configuration of a receiving unit and a transmitting unit of the communication terminal device according to the present embodiment.
02 to the low noise amplifier 103 via
The received signal amplified by the low noise amplifier 103 is
The signal is supplied to the reception mixer 104, and the oscillation output fl1 of the first local oscillator 105 is mixed with the reception signal to obtain a predetermined frequency band f
The received signal of ₀ is converted to an intermediate frequency signal.

The intermediate frequency signal output from the reception mixer 104 is supplied to the quadrature detector 106, and the second local oscillator 10
7 is mixed and subjected to quadrature detection, separated into an I component and a Q component, and the detected I component and Q component are supplied to an analog / digital converter 108, and the digital value of each component is supplied. Obtain data ID and QD. The data ID and QD are converted to a fast Fourier transform circuit (FFT).
Circuit) 109 to perform a discrete Fourier transform process at m points equal to the number of subcarriers to obtain parallel data of m symbols. Note that the number m of subcarriers is an integer value of 2 or more, and m is generally a relatively large value such as 32, for example.

M output from the fast Fourier transform circuit 109
The parallel data of the symbol is supplied to a parallel-serial conversion circuit 11.
0 to form a series of serial data, the converted serial data is used as reception data, and the obtained reception data is supplied to a data processing unit (not shown), and various data such as video display and audio reproduction are provided. Processing is performed. The configuration of the receiving system up to this point is described in the first embodiment with reference to FIG.
And the configuration described in FIG. 16 in the conventional example.

As a configuration of the transmission system, transmission data (serial data) is supplied to a serial-parallel conversion circuit 131,
The transmission data is converted into j parallel data (the value of j is a value corresponding to the number of carriers j of the multicarrier signal to be transmitted and is an integer smaller than the number of carriers m of the downlink multicarrier signal). . The j parallel data is converted into an inverse Fourier transform circuit (IFFT circuit) 1
32, and performs an inverse discrete Fourier transform at j points to obtain orthogonal digital baseband data ID and QD on the time axis. The baseband data ID and Q-
D is supplied to the digital / analog converter 113, and I
The analog signal of the component and the Q component is obtained.

The obtained I component and Q component signals are supplied to a quadrature modulator 114 and quadrature modulated based on the oscillation output fl2 of the second local oscillator 107. The signal orthogonally modulated by the quadrature modulator 114 is supplied to a transmission mixer 115,
By mixing an oscillation output fl1 of the first local oscillator 105, and frequency converted into a signal of a transmission frequency band f _0, the frequency-converted signal was amplified by the power amplifier 116, to the antenna 101 through the antenna switch 102 Supply,
Radio transmission.

By performing transmission processing in this manner, an uplink signal transmitted from the communication terminal apparatus to the base station becomes a multicarrier signal having j subcarriers. As described above, the value of j is smaller than the number m of subcarriers in the downlink. Here, when m = 32, j = 8.

Next, an example of the configuration of the base station according to the present embodiment will be described with reference to FIG. The transmitting / receiving antenna 201 is connected to a low-noise amplifier 203 via an antenna switch 202, and the received signal amplified by the low-noise amplifier 203 is received by the receiving mixer 20.
4 is supplied to and mixed with the oscillation output fl1 of the first local oscillator 205 to the received signal, converts the received signal in a predetermined frequency band f ₀ into an intermediate frequency signal.

The intermediate frequency signal output from the reception mixer 204 is supplied to the quadrature detector 206, where the second local oscillator 20
The oscillation output fl2 of No. 7 is mixed and subjected to quadrature detection to separate it into an I component and a Q component. Then, after the detected I component and Q component are passed through a first low-pass filter 215, they are supplied to a first analog / digital converter 216,
Digital data ID and QD of each component are obtained. The first low-pass filter 215 is a filter having a pass bandwidth suitable for passing a multicarrier signal of m subcarriers. Then, the converted data ID and QD are supplied to a first fast Fourier transform circuit (FFT circuit) 209. In the first fast Fourier transform circuit 209, m is equal to the maximum number of subcarriers.
Perform discrete Fourier transform processing of points (here, 32 points),
The data is supplied to the parallel-serial conversion circuit 210 as m-symbol parallel data, and is provided as one-series serial data. The converted serial data is supplied to the determination / selection circuit 211.

The I and Q components detected by the quadrature detector 206 are passed through a second low-pass filter 217, and then supplied to a second analog / digital converter 218, where each component is Digital data ID and Q-
Get D. The second low-pass filter 217 is a filter having a pass bandwidth suitable for passing a multicarrier signal of j subcarriers. Then, the converted data ID and QD are supplied to a second fast Fourier transform circuit (FFT circuit) 213. The second fast Fourier transform circuit 213 performs a discrete Fourier transform process at j points (here, 8 points) to provide j symbols (8 symbols) of parallel data, supplies the parallel data to the parallel-serial conversion circuit 214, and outputs one series. And supplies the converted serial data to the determination / selection circuit 211.

In the determination / selection circuit 211, the data supplied from one conversion circuit 210 and the data supplied from the other
4 to determine which data is considered to be correct received data, select the determined data, and output it as received data. It is supplied to a data processing system (not shown). The determination process in the determination / selection circuit 211 is performed using, for example, an error detection code added to each slot.

Here, the signal processed by the system from the first low-pass filter 215 to the parallel-serial conversion circuit 210 and the signal processed by the system from the second low-pass filter 217 to the parallel-serial conversion circuit 214 For example, as shown in FIG. 12A, the number of signals passing through the first low-pass filter 215 is m (here, 32
A multicarrier signal according to subcarrier sc1~sc32 of pieces), the bandwidth fw ₁ of the received signal, 32 a bandwidth of subcarriers, the first low-pass filter 215
Is a filter that passes signals in this band, and a band twice as large as the pass band of the first low-pass filter 215 is the bandwidth fw ₁ of the received signal.

The signal passing through the second low-pass filter 217 is a multicarrier signal composed of j (here, eight) subcarriers sc1 'to sc8', as shown in FIG. The signal bandwidth fw ₂ is a bandwidth corresponding to eight subcarriers, and the second low-pass filter 217 is a filter for passing a signal in this band, and has a band twice as large as the pass band of the second low-pass filter 217. Becomes the bandwidth fw ₂ of the received signal.

The configuration of the transmission system in the base station is the same as the configuration shown in FIG. 4 in the first embodiment.
That is, the transmission data (serial data) is supplied to the serial-parallel conversion circuit 211 to convert the transmission data into m parallel data. The m pieces of parallel data are supplied to an inverse Fourier transform circuit (IFFT circuit) 222 to perform an inverse discrete Fourier transform at m points to obtain orthogonal digital baseband data ID and QD on the time axis. . The baseband data ID and QD are supplied to the digital / analog converter 223 to obtain analog signals of the I component and the Q component.

The obtained signals of the I component and the Q component are supplied to a quadrature modulator 224, and are quadrature-modulated based on the oscillation output fl2 of the second local oscillator 207. The signal orthogonally modulated by the orthogonal modulator 224 is supplied to a transmission mixer 225,
By mixing an oscillation output fl1 of the first local oscillator 205, and frequency converted into a signal of a transmission frequency band f _0, the frequency-converted signal was amplified by the power amplifier 226, to the antenna 201 via the antenna switch 202 Supply,
Wireless communication is performed to each communication terminal device.

The wireless transmission processing between the communication terminal apparatus and the base station thus configured is performed in the same manner as in the first embodiment. Points That is, the channel setting, as shown in FIG. 3 or FIG. 8, not with arranging a plurality of wideband channels CH1~CH4 the available frequency band B within _0, can broadband channels arranged such that the guard band portion And narrowband channels CH5 and C
H6 is arranged, and at the time of communication between the terminal device and the base station in which the uplink shown in FIG. 10 is executed by low-speed access, the narrow-band channel in the uplink period is transmitted by the control sequence shown in FIG. 5 or FIG. The used communication and the communication using the wideband channel in the downlink period are performed.
The signal transmitted at the time of low-speed access according to the first embodiment is a single carrier signal, but the second embodiment is different from the first embodiment in that the signal is a multicarrier signal with a limited number of carriers. It is.

By performing low-speed access using a signal having a limited number of carriers as described above, the maximum number of carriers that can be transmitted on the prepared narrow-band channel is set, thereby improving the use efficiency of the narrow-band channel. Thus, the prepared usable frequency band can be more effectively utilized.

[0094] By adopting the configuration of the base station shown in the second embodiment, both the reception processing of the uplink low-speed access and the reception processing of the high-speed access from the communication terminal apparatus are performed. Is processed by passing through low-pass filters 215 and 217 suitable for the respective transmission bandwidths, so that demodulation processing can be performed from the reception signal limited to the pass bandwidth suitable for the respective number of subcarriers. Demodulation processing of the data of the number of carriers can be performed with good sensitivity. In particular, since the processing is performed by narrowing the pass band of the received signal at the time of low-speed access, useless noise power and interference waves can be removed, and the receiving sensitivity can be increased. As described above, since the reception processing on the base station side can be performed with high sensitivity, the load on the power amplifier on the terminal device side can be reduced, and the power required for transmission on the terminal device can be reduced. . In addition, the out-of-band interference wave can be efficiently removed, and from this point, the receiving sensitivity can be improved.

Here, the effect of improving the receiving sensitivity according to this embodiment will be described. The receiving sensitivity Ps (for example, when the bit error rate is 1%) can be expressed by the following equation.

[0096]

## EQU1 ## Ps = C / N [dB] + kTBF [dB]

Here, C / N is a ratio of carrier to noise when a 1% error occurs, and is a value determined by the modulation method of each subcarrier, and does not basically depend on the number of subcarriers. k is Boltzmann's constant, T is absolute temperature and kT = 174 at room temperature.
It becomes dBm / Hz. F is the noise figure (NF) of the receiver. B is the noise bandwidth of the receiver, and when the band is limited at the baseband, the passband of the low-pass filter is 2
The value is doubled. Here, as shown in FIG. 12, when the value of B can be reduced to 1/4 by reducing the number of subcarriers,
Since other parameters are the same, Ps is also 1/4, that is, 6
It can be set lower by dB. This gives a sensitivity of 6 dB
It will be better. To be able to improve the sensitivity by 6 dB corresponds to the fact that the transmission power on the terminal device side may be reduced by 6 dB.

Although the number of m subcarriers is set to 32 and the number of j subcarriers is set to 8, here,
The number of subcarriers that satisfies the relationship of m> j is not limited to this. For example, as shown in the first embodiment, the base station having the configuration shown in the second embodiment is applied to a case where the number of j subcarriers is one and a so-called single carrier signal is used. You may.

Also, in this example, 2 of each bandwidth is used.
In this configuration, one low-pass filter capable of variably setting the bandwidth is provided, and the output of the one low-pass filter can be variably processed according to the number of subcarriers of the received data. Alternatively, the pass band width of the low-pass filter may be changed according to the number of subcarriers of the received data. In particular, when it is known in advance whether the access is a low-speed access or a high-speed access, a low-pass filter or an analog /
Only one system of the digital converter, the fast Fourier transform circuit, and the parallel-serial converter circuit may be provided, and the processing in each circuit may be changed according to the number of subcarriers received at that time. .

In each of the above embodiments, the MMA
Although the example is applied to the wireless transmission system C, the processing of the present invention can of course be applied to other various data transmission systems.

[0101]

According to the communication method described in claim 1,
The downlink from the base station to the communication terminal is transmitted as a multicarrier signal having a large number of subcarriers using a wideband channel, and the uplink from the communication terminal to the base station is transmitted using a narrowband channel. Is transmitted as a multi-carrier signal (or a single carrier signal with one carrier) having a small bandwidth, and the communication terminal side does not need to perform multi-carrier signal transmission processing with a wide band.
As a result, the transmission processing can be efficiently performed with a simple configuration, the load on the hardware of the communication terminal can be reduced, and the prepared frequency band can be used efficiently by setting the wideband channel and the narrowband channel.

According to the communication method described in claim 2, in the invention described in claim 1, the narrow-band channel is
By arranging in the guard band portion of the transmission band, efficient data transmission can be performed by effectively utilizing the guard band portion of the usable frequency band.

According to the communication method described in claim 3, in the invention described in claim 1, one of the wideband channels
One channel is set as a control channel, and after access using this control channel, uplink communication is performed using a narrow band channel, so that access when a narrow channel and a wide band channel are mixed is arranged. Performs well with simple control.

According to the communication method described in claim 4, in the invention described in claim 3, the control channel set by the wideband channel is a multi-carrier signal or a single-carrier signal using only less than m sub-carriers. By transmitting the carrier signal, the same transmission processing system as that used in the communication channel transmission processing can be used on the terminal device side even in the transmission processing on the control channel, and the burden on the terminal device side can be reduced.

According to the base station apparatus described in claim 5,
The signal is processed as a multicarrier signal with a large number of subcarriers transmitted on a wideband channel, and a signal transmitted from the communication terminal device is a multicarrier signal with a small number of subcarriers (or a single carrier signal using one carrier). It is possible to obtain a base station device that can efficiently perform transmission processing in a case where transmission is performed using a narrowband channel and a wideband channel and a narrowband channel are mixedly arranged.

According to the base station apparatus described in claim 6,
In the invention as set forth in claim 5, as the receiving means, a wideband channel is also received in addition to the narrowband channel.
As demodulation means, in addition to demodulation of data modulated on j subcarriers, demodulation of data modulated on m subcarriers also enables access using only a wideband channel. Can access the terminal device.

According to the base station apparatus described in claim 7,
In the invention described in claim 5, the frequency of the narrow band channel received by the receiving means is a frequency corresponding to the guard band part of the frequency band of the wide band channel transmitted by the transmitting means. Thus, it is possible to efficiently perform uplink reception.

According to the base station apparatus described in claim 8,
In the invention set forth in claim 5, by setting one of the wideband channels transmitted by the transmission means as a control channel, control information from the base station apparatus can be broadcasted using only one wideband channel. well,
Control processing in the base station device is simplified.

According to the ninth aspect of the present invention, a signal received by the communication terminal is processed as a multicarrier signal having a large number of subcarriers transmitted on a wideband channel and transmitted from the communication terminal. The signal is transmitted as a multi-carrier signal with a small number of subcarriers (or a single carrier signal by one carrier) on a narrow band channel, and transmission processing when a wide band channel and a narrow band channel are arranged in a mixed manner. Can be performed efficiently.

According to a tenth aspect of the present invention, in the invention of the ninth aspect, the frequency of the narrow band channel transmitted by the transmitting means is the guard band portion of the frequency band of the wide band channel received by the receiving means. , The transmission of the uplink can be performed efficiently using the guard band unit.

According to an eleventh aspect of the present invention, in the invention of the ninth aspect, the receiving means also performs the reception of the control channel prepared for the wideband channel, so that the base station can transmit the wideband channel. And access to the base station apparatus can be performed satisfactorily by receiving control information transmitted using

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of wireless processing of a terminal device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an example of a frame configuration according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an example of a channel setting state according to the first embodiment of the present invention.

FIG. 4 is a block diagram illustrating an example of wireless processing of a base station according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an example of a control sequence according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a frame configuration of an access example (an example in which a low-speed dedicated slot is prepared) on a control channel according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram of a frame configuration of an access example (an example in which low-speed and high-speed slots are prepared) on a control channel according to the first embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an example of another channel setting state (an example in which a control channel is set to a narrow band channel) according to the first embodiment of the present invention.

FIG. 9 is an explanatory diagram showing an example of another control sequence (an example in which a control channel is set to a narrow band channel) according to the first embodiment of the present invention.

FIG. 10 is a block diagram illustrating an example of wireless processing of a terminal device according to a second embodiment of the present invention.

FIG. 11 is a block diagram illustrating an example of wireless processing of a base station according to the second embodiment of the present invention.

FIG. 12 is an explanatory diagram illustrating an example of a reception band at a base station according to the second embodiment of the present invention.

FIG. 13 is a configuration diagram showing a conventional multimedia mobile access system.

FIG. 14 is a block diagram showing a configuration of a conventional MMAC base station.

FIG. 15 is a block diagram illustrating a configuration of a conventional MMAC terminal device.

FIG. 16 is a block diagram illustrating an example of wireless processing by conventional OFDM.

FIG. 17 is an explanatory diagram showing an example of a conventional MMAC frame configuration.

[Explanation of symbols]

121, 131: serial-parallel conversion circuit, 122: baseband filter, 132: inverse fast Fourier transform circuit (I
FFT circuits), 209, 213 fast Fourier transform circuits (FFT circuits), 210, 212, 214 parallel-serial converter circuits, 211 decision / selection circuits, 215, 217 ...
Low-pass filter

Claims (11)

[Claims] 1. A communication method for performing data communication between a base station and a predetermined communication terminal, comprising: distributing data to m (m is an integer of 2 or more) subcarriers within a prepared transmission band; Setting a wideband channel that can be transmitted as a multicarrier signal and a narrowband channel that transmits as a multicarrier signal or a single carrier signal using only j (j is an integer smaller than m) subcarriers; A communication method for performing downlink communication from a station to the communication terminal using the broadband channel, and performing uplink communication from the communication terminal to the base station using the narrowband channel. 2. The communication method according to claim 1, wherein the narrow band channel is arranged in a guard band part of the transmission band. 3. The communication method according to claim 1, wherein one of the wideband channels is set as a control channel, and after the access using the control channel, the uplink communication is performed on a narrowband channel. Method. 4. The communication method according to claim 3, wherein the control channel set in the wideband channel is:
A communication method for transmitting a multi-carrier signal or a single-carrier signal using only less than m sub-carriers. 5. A base station apparatus for performing bidirectional communication with a predetermined communication terminal, wherein data to be transmitted to the communication terminal is distributed to m (m is an integer of 2 or more) subcarriers. Modulating means for modulating the modulated multi-carrier signal; transmitting means for transmitting the multi-carrier signal modulated by the modulating means in a frequency band prepared as a wide-band channel; A base station comprising: receiving means for receiving a signal transmitted on a channel; and demodulating means for demodulating data (j is an integer smaller than m) subcarriers modulated from a reception output of the receiving means. apparatus. 6. The base station apparatus according to claim 5, wherein the receiving means also receives a wideband channel in addition to the narrowband channel, and the demodulation means demodulates data modulated to j subcarriers. In addition, a base station apparatus that demodulates data modulated on m subcarriers. 7. The base station apparatus according to claim 5, wherein the frequency of the narrowband channel received by the receiving means is:
A base station apparatus having a frequency corresponding to a guard band part of a frequency band of a wideband channel transmitted by the transmitting means. 8. The base station apparatus according to claim 5, wherein one of the wideband channels transmitted by said transmitting means is set as a control channel. 9. A communication terminal device for performing bidirectional communication with a predetermined base station, comprising: receiving means for receiving a signal transmitted in a frequency band prepared as a wideband channel; and receiving output of the receiving means. From m (m is an integer of 2 or more)
Demodulation means for demodulating data dispersed and modulated on subcarriers, and modulation means for converting data to be transmitted to the base station into data modulated on j (j is an integer smaller than m) subcarriers. A communication terminal device comprising: a transmission unit that transmits an output modulated by the modulation unit in a frequency band prepared as a narrowband channel. 10. The communication terminal device according to claim 9, wherein the frequency of the narrowband channel transmitted by the transmitting means is:
A communication terminal device having a frequency corresponding to a guard band portion of a frequency band of a wideband channel received by the receiving means. 11. The communication terminal device according to claim 9, wherein said receiving means also performs reception of a control channel prepared for a wideband channel.