JP2000092009A - Communication method, transmitter and receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow each receiver or the like to apply communication processing to information with a required minimum processing quantity of itself in the case of multiplexing channels for communication through various transmission routes by each by adopting special arrangement for transmission symbols for each channel on a frequency axis. SOLUTION: Subcarriers are allocated on a frequency axis for each channel as shown in the following: the subcarriers for a channel 1 are allocated with spacing of 16 kHz from a reference frequency fc (shown in Fig. A), the subcarriers for a channel 2 are allocated with spacing of 16 kHz from a frequency shifted by 4 kHz from the reference frequency fc (shown in Fig. B), the subcarriers for a channel 3 are allocated with spacing of 16 kHz from a frequency shifted by 8 kHz from the reference frequency fc (shown in Fig. C), and the subcarriers for a channel 4 are allocated with spacing of 16 kHz from a frequency shifted by 12 kHz from the reference frequency fc (shown in Fig. D). Signals of each channel are transmitted as a radio wave to cause the subcarriers to be allocated on a radio transmission channel with spacing of 4 kHz (shown in Fig. E) resulting that signals of the 4 channels are multiplexed and transmitted in one transmission band.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication method in digital wireless communication suitable for application to a wireless communication system such as a cellular wireless telephone system, and a transmitter and a receiver to which the communication method is applied.

[0002]

2. Description of the Related Art Conventionally, like a wireless telephone system,
As a communication method for efficiently communicating by sharing a wide frequency band among a plurality of users, for example, DS-CDMA (Di-
rect Sequence-Code Division Multiple Access). In the DS-CDMA system, a transmission signal sequence is spread (multiplied) by a code to generate a broadband signal and transmit it. On the receiving side, an effect called despreading is obtained by multiplying the received signal by the same spreading code as that on the transmitting side, and only a desired signal component is extracted from the received signal.

FIG. 27 shows a transmission configuration in a conventional cellular radio communication system to which the DS-CDMA system is applied. The information bit stream obtained at the input terminal 1 is subjected to processing such as encoding and interleaving at the coding unit 2 and then supplied to the multiplier 3 where the information bit stream is multiplied by the channel allocation target code obtained at the terminal 3. Spread. The spread bit stream is randomized by a long code obtained at a terminal 4 a in a multiplier 4 in the next stage, and then mapped to a transmission symbol in a symbol mapping unit 5. There are various mapping methods depending on the communication method.

The transmission signal mapped by the symbol mapping section 5 is multiplexed with another system transmission signal by an adder 6 if necessary, supplied to a transmission processing section 7, and subjected to high-frequency processing such as modulation. After that, the frequency is converted to a frequency band in which wireless transmission is performed, and wirelessly transmitted from the antenna 8.

[0005] Assuming that the information bit stream obtained at the input terminal 1 is, for example, 8 kbps, the coding unit 2 encodes the information bit stream at a coding rate of 1/2, and the bit rate of the coded bits becomes 16 kbps. 64 diffusion rate in vessel 3
1024kcps (cps is Chip Per Second)
) Bit stream. When the bit rate of the information bit stream is different, the bit rate of the transmission signal can be made constant by changing the spreading factor in the multiplier 3.

[0006] For other transmission systems to be added by the adder 6, if the bit stream of the transmission signal supplied to the adder 6 is constant, the information bit stream supplied to the coding unit 2 of each transmission system is provided. Various types can be mixed.

Next, a configuration for receiving a signal subjected to transmission processing in the conventional DS-CDMA system will be described with reference to FIG. A signal in a predetermined frequency band received by the antenna 11 is frequency-converted into an intermediate frequency signal or the like by the reception processing unit 12, and the frequency-converted received signal is demodulated to obtain a baseband symbol sequence. From this symbol sequence, a bit extraction unit 13 extracts a received bit stream. The extracted received bit stream is supplied to a multiplier 14, where it is multiplied by a long code obtained at a terminal 14a and descrambled, and the multiplied output of the multiplier 14 is supplied to a multiplier 15 to be supplied to a terminal 15a. Is multiplied by the obtained despreading code to perform despreading processing to obtain an encoded bit stream. Then, the encoded bit stream is decoded by the decoding unit 16 and an information bit stream is obtained at a terminal 17.

[0008] When the above-mentioned signal of 8 kbps information bit stream is transmitted as a 1024 kcps bit stream, and the signal of FIG.
The information is despread by the multiplier 15 at the despreading factor 64 to obtain an information bit stream of 8 kbps. Further, by changing the despreading rate of the despreading code obtained at the terminal 15a, it is possible to cope with information bit streams of other bit rates.

In the above description, a case has been described where information bit streams of a plurality of bit rates are mixed and transmitted wirelessly in the DS-CDMA system.
In the case of wireless transmission by the (Time Division Multiple Access) method, it is possible to mix information bit streams of a plurality of bit rates. FIG. 29 is a diagram showing one frame structure in the case of an 8TDMA structure in which one frame is composed of eight time slots from slot 1 to slot 8.

[0010] Here, assuming slot allocation in the case where the transmission rate per slot is 8 kbps, for example, slots 1 and 2 are allocated to users A and B having a transmission rate of 8 kbps, respectively. Communication is performed at a transmission rate of 8 kbps. Further, the user C having a transmission rate of 16 kbps is allocated two slots of slot 3 and slot 4, and performs communication at 16 kbps. If the transmission rate is 3
To the user D of 2 kbps, four slots from slot 5 to slot 8 are allocated, and communication at 32 kbps is performed. In this way, the base station or the like variably sets the number of slots to be assigned to each user in one frame according to the transmission rate at the time of transmission request from each user. It is possible to cope with wireless transmission by mixing bit streams.

An OFDM (Orthogonal Frequency D)
When wireless transmission is performed by a multicarrier method called an ivision Multiplex (orthogonal frequency division multiplexing) method, a transmission configuration, for example, has conventionally been performed with a configuration shown in FIG. This configuration is based on DAB (Digital Audio Broadcasti
ng), which is applied to digital audio broadcasting, an information bit stream obtained at a terminal 21 is subjected to a process such as encoding by a coding unit 2 and then converted to a transmission symbol by a symbol mapping unit 23. Is mapped. Then, the transmission symbols are supplied to the mixing circuit 24 and multiplexed with other transmission data. The multiplexing here generates a multiplexed symbol stream by simply connecting them in series. For example, 6 per channel
When 4 ksps symbols are multiplexed for 18 channels,
The transmission rate of the multiplexed symbol stream is 64ks
ps × 18 = 1152 ksps.

[0012] The multiplexed symbol stream is:
The symbols are rearranged by the frequency interleaving in the frequency conversion unit 25, and the symbols of the respective channels are arranged separately. This rearranged symbol stream is supplied to an inverse Fourier transform circuit (IFFT circuit) 2
In step 6, a multicarrier signal arranged on the frequency axis is obtained by the inverse Fourier transform process. The output of the IFFT circuit 26 is subjected to wireless transmission processing in the transmission processing unit 27, and is wirelessly transmitted in a predetermined frequency band.

As a configuration for receiving the multicarrier signal, as shown in FIG. 31, a signal in a desired frequency band received by an antenna 31 is used as a baseband signal by a reception processing unit 32. Here, since the baseband signal component of the multicarrier signal is a signal in which information is arranged on the frequency axis, a fast Fourier transform circuit (FFT circuit) 32
To extract the subcarriers arranged on the frequency axis. At this time, the symbols output by the Fourier transform process form a subcarrier group of the entire received signal band.

The converted signal of the subcarrier group is supplied to a symbol selecting section 34, and a symbol is extracted from a position of a symbol of a desired channel arranged by frequency interleaving performed on the transmitting side. Further, the extracted symbol stream is supplied to a bit extracting unit 35 to extract an encoded bit stream, and the encoded bit stream is supplied to a decoding unit 36 to obtain an information bit stream at an output terminal 37. .

In the conventional OFDM system, multiplexing is performed by allocating symbols of different channels to subcarriers. Therefore, the Fourier transform circuit (FFT circuit) included in the receiver transforms symbols for all channels multiplexed and transmitted, and selects a channel after the transform.

[0016]

SUMMARY OF THE INVENTION The above-mentioned DS-CDM
In a cellular communication system to which the A method is applied, by fixing a used frequency band and changing a spreading factor,
Variable rate data transmission is possible. By fixing the used frequency band, it is possible to configure a terminal device that provides a variable bit rate service with only a single high-frequency circuit.

However, the DS-CDMA system has a very complicated communication control system. For example, when applied to the cellular system, the DS-CDMA system prevents handoff processing for switching base stations and interference with other communication in the system. Power control and the like must be performed with high accuracy. In addition, in the DS-CDMA system, since all channels basically share the same frequency band and there is no orthogonality of each channel, even one terminal device in which transmission power control is not performed correctly exists. When
There is a risk that the whole system will not function, and it cannot be said that the system is suitable for performing complicated processing such as variable transmission rate.

Further, when the transmission rate variable processing is applied in the DS-CDMA system, the demodulation part is several kb.
Even a terminal device that communicates at a low transmission rate of about ps requires the same arithmetic processing as a terminal device that communicates at the highest transmission rate that can be transmitted by the system. It will increase significantly.

On the other hand, when a variable transmission rate is realized in a communication system to which the above-described TDMA system is applied, the maximum transmission rate per channel is basically [bit rate at the time of allocating one slot] × [TDMA Number], and the upper and lower limits of the transmission rate are determined by the number of TDMAs. Therefore, if the range in which the transmission rate changes is very large, for example, from about several kbps to about 100 kbps, it is practically impossible to correspond to the transmission rate desired by the user only by slot allocation. is there. It is not impossible if the number of time slots in one frame is extremely large, but it is not realistic from the viewpoint of communication control and the like.

When multiplexing at a variable transmission rate is realized in a communication system to which the conventional OFDM system described above is applied, multiplexing is performed by allocating symbols of different channels to subcarriers. However, the Fourier transform circuit included in the receiver needs to convert symbols for all channels to be multiplexed and transmitted, and has a problem that a very large number of conversion processes are required.

[0021] An object of the present invention is to provide an information communication processing system in which each receiver or the like has a minimum processing amount required by itself when multiplexing channels for performing communication at various transmission rates. Is made possible.

[0022]

According to a first aspect of the present invention, there is provided a communication method in which a plurality of channels are set in a predetermined band, and transmission symbols in each set channel are distributed to a plurality of subcarriers. A multi-carrier signal is used, and the transmission symbols on each channel are arranged on the frequency axis at every Nth power of 2 (N is any positive number) with respect to a reference frequency interval. .

According to this communication method, a transmission signal in which each channel is multiplexed into a multicarrier signal includes:
Transmission symbols of each channel are arranged at predetermined frequency intervals.

In a communication method according to a second aspect of the present invention, a plurality of channels are set in a predetermined band, and radio communication in each of the set channels is performed by using a multicarrier signal in which transmission symbols are dispersed among a plurality of subcarriers. Along with, as a subcarrier assigned to each channel, a predetermined number of subcarriers are used, and after performing differential modulation between adjacent ones of the subcarriers assigned to each channel and transmitting, on the receiving side, Differential demodulation is performed between adjacent ones.

According to this communication method, the channel arrangement is such that a multicarrier signal using subcarriers of a predetermined number is used, and differential modulation is performed between adjacent subcarriers of each channel. In addition, transmission processing and reception processing can be performed using only signals of each channel.

Further, the transmitter of the present invention generates a multicarrier signal in which transmission symbols are dispersed on a plurality of subcarriers, and arranges transmission symbols in one channel of the multicarrier signal on the frequency axis. Every Nth power of 2 with respect to the reference frequency interval (N is any positive number)
Then, the generated multicarrier signal is transmitted as a predetermined channel among a plurality of channels set within a predetermined band.

According to this transmitter, transmission symbols of each channel are arranged at predetermined frequency intervals, and a multicarrier signal in which each channel is multiplexed is transmitted.

Further, the receiver of the present invention receives a multicarrier signal in which transmission symbols are dispersed in a plurality of subcarriers, and converts transmission symbols received in one channel into N by 2 with respect to a reference frequency interval. The reception processing is performed at frequency intervals of every power (N is an arbitrary positive number).

According to this receiver, the transmission symbols of each channel are arranged at predetermined frequency intervals, and a multicarrier signal in which each channel is multiplexed can be received.

[0030]

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

The present embodiment is an example applied to a cellular radio telephone system. FIG. 1 shows a transmission configuration on the base station side or the terminal device side in the system of this example. Here, the transmission rate is 32 kb
The configuration is such that data of four rates of ps, 64 kbps, 96 kbps, and 128 kbps can be transmitted.

The information bit stream obtained at the terminal 101 at any one of the above transmission rates is subjected to coding processing such as coding and interleaving at the coding section 102, and is performed at a predetermined coding rate such as a coding rate of 1/2. Encode. Each bit coded by the coding unit 102 is supplied to a symbol mapping unit 103 and mapped to a transmission symbol. Processing such as QPSK processing, 8PSK processing, and 16QAM processing can be applied to the transmission symbol mapping processing here. Alternatively, differential modulation may be performed on the frequency axis or the time axis.

The transmission symbols generated by symbol mapping section 103 are supplied to null symbol insertion section 104. Null symbol insertion section 104 regularly inserts a symbol whose amplitude (energy) is 0 according to the transmission rate at that time, and changes the symbol rate to the maximum transmission rate (regardless of the transmission rate of the original information bit stream). Here, a process for keeping the rate constant at 128 kbps) is performed.

FIG. 2 shows an example of the insertion state of the null symbol. The symbol position indicated by a circle is the symbol position of the original transmission data, and the symbol position indicated by a cross is:
This is the position of the 0 symbol inserted by the null symbol insertion unit 104. For example, when the transmission rate of the information bit stream is 32 kbps, as shown in FIG.
It is converted into transmission data of the number of symbols corresponding to ps (that is, four times). Also, the transmission rate of the information bit stream is 6
In the case of 4 kbps, one null symbol is inserted between the original symbols as shown in FIG.
Is converted into transmission data of the number of symbols corresponding to (i.e., twice). Also, the transmission rate of the information bit stream is 96
In the case of kbps, as shown in FIG. 2C, one null symbol is inserted for each of the original three symbols, and converted into transmission data of the number of symbols corresponding to 128 kbps (that is, 4/3 times). . Also, the transmission rate of the information bit stream is 1
In the case of 28 kbps, as shown in FIG. 2D, transmission data of the same number of symbols is used without inserting a null symbol.

Here, the insertion rate R of null symbols in null symbol insertion section 104 is defined by the following equation.

[0036]

## EQU1 ## where M is the maximum transmission rate in the transmission band here (128 kbps), and D is the transmission rate in the corresponding channel.

The processing in the null symbol insertion section 104 is processing for controlling the symbol rate to be 2 ^N times (N is any positive number) by inserting null symbols. However, in the process shown in FIG. 2C, that is, when transmitting at a rate of 96 kbps, the value of N is not an integer, but the null symbol insertion rate R = 1/1 based on the above equation (1). This is a process using the rule of No. 4.

The transmission symbol into which the null symbol is inserted by null symbol insertion section 104 is transmitted to random phase shift section 1
At 05, a scrambling process (or another scrambling process) by a random phase shift is performed, and the scrambled transmission symbol is subjected to an inverse Fourier transform (IFFT).
The signal stream is supplied to the processing unit 106, and the symbol stream arranged on the time axis is converted into a multi-carrier signal in which subcarriers are arranged on the frequency axis by an inverse fast Fourier transform operation. The signal converted by the inverse Fourier transform processing unit 106 is supplied to a guard time adding unit 107 to add a guard time, and the windowing processing unit 108 multiplies the signal of each predetermined unit by windowing data for transmission. . The transmission signal multiplied by the windowing data is supplied to a transmission processing unit 109, which convolves the high-frequency signal into a predetermined transmission frequency band and converts the frequency-converted transmission signal to the antenna 1
10. Wireless transmission is performed from 10.

FIG. 3 shows a configuration in which a terminal device or a base station receives a signal wirelessly transmitted in such a configuration. The reception processing unit 112 to which the antenna 111 is connected receives a signal in a predetermined transmission frequency band and converts the signal into a baseband signal. The converted baseband signal is supplied to a windowing processing unit 113, and after multiplying the signal for each predetermined unit by windowing data for reception, the signal is supplied to a Fourier transform (FFT) processing unit 114, and the converted signal is output on a frequency axis. Is converted into a symbol stream arranged on the time axis.

The converted symbol stream is subjected to a descrambling process opposite to the scrambling process at the time of transmission by the descrambling unit 115. The descrambled symbol stream is supplied to the symbol selection unit 116. The symbol selection unit 116 performs a process of selecting a symbol other than the null symbol inserted by the null symbol insertion unit 104 (see FIG. 1) at the time of transmission (that is, removing the null symbol). The symbol stream from which the null symbols have been removed is supplied to a bit extraction unit 117, where coded bits are extracted, and the extracted bit data is decoded.
8 for decoding, and a decoded information bit stream is obtained at a terminal 119.

The symbols extracted by the symbol selection unit 116 differ depending on the transmission rate of the information bit stream to be transmitted. That is, as shown in FIG. 2, the position of a null symbol having an amplitude of 0 inserted at the time of transmission varies depending on the transmission rate, and for each transmission rate, a process of extracting only the symbol indicated by a circle is performed. . By performing this processing, transmission at a transmission rate of 32 kbps to 128 kbps can be performed using the same communication bandwidth.

Here, a case where transmission is performed at a variable transmission rate from 32 kbps to 128 kbps has been described. By the same processing, communication at M / 2 ^N kbps can be performed in a band in which communication with a maximum bit number of Mkbps can be performed. It is possible. In this case, on the transmitting side, the generated symbols and null symbols are inserted in the patterns shown in Table 1 below. In Table 1, symbols indicated by white circles are symbols generated by information bits, and symbols indicated by black circles are null symbols.

[0043]

[Table 1]

By performing the communication as described above, it is possible to perform from low-speed transmission to high-speed transmission using the same communication bandwidth. For example, only a single high-frequency circuit (transmission processing circuit or reception processing circuit) is used. Communication at a variable transmission rate is possible even in a terminal device that is not provided.

The difference between the minimum transmission rate and the maximum transmission rate can be further increased by performing the transmission processing described in the first embodiment using a TDMA structure. FIG. 4 is a diagram showing an example of a frame structure in this case. For example, in the case of 8TDMA in which one frame is composed of 8 time slots from slot 1 to slot 8, 32 kbps (null symbol Assuming that a band capable of transmitting a multi-carrier signal at a rate from the insertion rate R = 3/4) to 128 kbps (null symbol insertion rate R = 0/4) is set, only one slot is used in one frame. In this communication, transmission is performed at a rate of 32 kbps to 128 kbps, and two frames of one frame are transmitted.
In communication using slots, transmission is performed up to a rate of 256 kbps. By increasing the number of slots to be used in the following, a maximum of 8 slots are used, and when a null symbol insertion rate R = 0/4, 128 kbps × Communication at a transmission rate of 8 = 1024 kbps becomes possible.

The portion where the null symbol is inserted in the transmission processing described in the first embodiment (subcarrier using the null symbol) can be used for communication in another system. As described above, by using the subcarrier at the insertion position of the null symbol for another communication, multiplex communication can be performed efficiently. For example, in the transmission process shown in FIG.
When transmitting an information bit stream at a rate of 64 kbps, transmission of an information bit stream at a rate of 2 kbps in one of two systems is performed by performing communication of another system at a null symbol insertion position. Is possible. Similarly, in the case of a rate of 32 kbps, 32 kbps of four systems
Is possible in one transmission band. Further, transmission at a rate of 96 kbps and transmission at a rate of 32 kbps can be performed in one transmission band.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. Also in the present embodiment,
This is an example in which the present invention is applied to a cellular radio telephone system. In this example, multiplex transmission is performed from one transmitter. This multiplex transmission can be applied, for example, when transmitting a plurality of transmission signals from a base station at the same time.
In this embodiment, except for the configuration for performing multiplex communication,
The processing is basically the same as the processing described in the first embodiment, and the configuration of the receiving system is omitted.

FIG. 5 is a diagram showing a transmission configuration according to the present embodiment. Here, channel 1, channel 2, ...
An information bit stream of the number N of channels N (N is an arbitrary integer) is transmitted to terminals 121a, 121b,.
1n. Each terminal 121a to 121n
Are obtained here as bit streams having the same transmission rate.
Each of the coding units 122a, 122b... 12
2n to individually perform coding processing such as encoding and interleaving. Coding unit 122
The bit stream of each channel coded by a to 122n is separated by a different symbol mapping unit 123
a, 123b... 123n, and individually maps to transmission symbols for each channel. Here, the mapping process to the transmission symbol includes QPSK process, 8
Processing such as PSK processing and 16QAM processing can be applied.
Alternatively, differential modulation may be performed on the frequency axis or the time axis.

Symbol mapping unit 1 for each channel
The transmission symbols generated by 23a to 123n are supplied to a mixing circuit (multiplexer) 124 and mixed into one symbol stream. FIG. 6 is a diagram simply showing the concept of the processing in the mixing circuit 124. Here, for example, a symbol stream having four channels from channel 1 to channel 4 is converted into a symbol stream of one system. The symbol stream of channel 1 is obtained at terminal 124a of mixing circuit 124, the symbol stream of channel 2 is obtained at terminal 124b of mixing circuit 124, and the symbol stream of channel 3 is
4 and the symbol stream of channel 4 is obtained at terminal 124d of mixing circuit 124.
At this time, the contact 1 of the switch constituting the mixing circuit 124
24m performs a process of periodically selecting each of the terminals 124a to 124d and outputs the result.

FIG. 7 is a diagram showing an example of this mixed state.
For example, in the state shown in FIGS. 7A, 7B, 7C, and 7D, when symbol streams of different channels 1, 2, 3, and 4 are obtained, the symbols of each channel are sequentially selected.
One mixed stream shown in FIG. 7E is obtained. For example, when the stream of each channel is a symbol of an information bit stream at a rate of 32 kbps,
A symbol stream corresponding to an information bit stream having a rate of ps is obtained. If the transmission timing of the symbols of each channel is not synchronized, a synchronization process using a buffer memory or the like is required.

Returning to the description of FIG. 5, the transmission symbols mixed by the mixing circuit 124 are
Performs scramble processing (or other scramble processing) by random phase shift, supplies the scrambled transmission symbol to an inverse Fourier transform (IFFT) processing unit 126, and performs inverse fast Fourier transform arithmetic processing.
The symbol stream arranged on the time axis is converted into a multicarrier signal in which subcarriers are arranged on the frequency axis. The signal converted by the inverse Fourier transform processing unit 126 is supplied to a guard time adding unit 127 to add a guard time, and the windowing processing unit 128 multiplies the signal of each predetermined unit by windowing data for transmission. . The transmission signal multiplied by the windowing data is supplied to a transmission processing unit 129, where the high-frequency signal is convolved and frequency-converted into a predetermined transmission frequency band.
0 is transmitted by radio.

On the side that receives the signal transmitted by radio in this way (for example, a terminal device that receives a signal from a base station), the reception processing is performed by the configuration of FIG. 3 described in the first embodiment, for example. By doing so, a signal of an arbitrary channel can be extracted and processed.

Since the case where multiplexing of four channels is performed has been described as an example, the appearance period of the symbol of each channel in the multiplexed symbol stream (E in FIG. 7) is 4, The maximum number of multiplexed channels is not limited to this. The maximum number of multiplexed channels is 2 ⁿ (where n is a positive integer: n = 1,
2, 3, 4}). In this case, the symbol appearance cycle of each channel is 2 ⁿ , which is the same as the maximum multiplex number. The number of channels used in actual communication
When the number is smaller than the maximum multiplexing number, a null symbol (a symbol having an amplitude of 0) described in the first embodiment may be inserted as an unused channel symbol.

Next, a third embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. This embodiment is also an example in which the present invention is applied to a cellular wireless telephone system. In this example, as in the second embodiment, multiplex transmission is performed from one transmitter. The same reference numerals are given to the portions corresponding to the second embodiment, and the detailed description is omitted.

Here, the case of the present embodiment is an example in which the transmission rate of each channel is different, and FIG. 8 is a diagram showing a transmission configuration in the present embodiment. Here, an information bit stream of channel number 3 of channel 1, channel 2 and channel 3 is supplied to terminals 131a,
It is assumed that these are obtained at 131b and 131c. The transmission rate of each channel is, for example, 32 kbps for channel 1 and channel 2, and 64 kbps for channel 3.
kbps. The information bit stream of each channel obtained at each of the terminals 131a to 131c is supplied to another coding unit 132a, 132b, 132c, and individually performs coding processing such as encoding and interleaving. Coding units 132a, 132
The bit streams of channel 1 and channel 2 encoded by b are supplied to the symbol mapping units 133a and 133b for the respective channels, and are individually mapped to transmission symbols for each channel. Further, the bit stream of channel 3 is divided into two bit streams, and one bit stream is supplied to the symbol mapping unit 133c, and the other bit stream is supplied to the symbol mapping unit 13c.
3d and separately mapped to transmission symbols.

Each of the symbol mapping units 133a to 133
The transmission symbol mapped by d
And multiplex them into one system. FIG. 9 shows an example of a multiplexed state in which the symbol streams of channel 3 divided into two systems are periodically arranged at the same interval, and the symbol stream of channel 1 and the channel stream are interposed therebetween. 2 symbol streams are arranged periodically. That is, for example, the arrangement of channel 1, channel 3, channel 2, channel 3 # is repeatedly set.

This multiplexed symbol stream is
The random phase shift section 125 performs scrambling processing (or other scrambling processing) by random phase shift, supplies the scrambled transmission symbol to an inverse Fourier transform (IFFT) processing section 126, and performs an inverse fast Fourier transform operation Then, the symbol stream arranged on the time axis is converted into a multicarrier signal in which subcarriers are arranged on the frequency axis. The signal converted by the inverse Fourier transform processing unit 126 is output to the guard time adding unit 1
27, a guard time is added, and a windowing processing unit 128 multiplies the signal of each predetermined unit by windowing data for transmission. The transmission signal multiplied by the windowing data is
The transmission signal is supplied to the transmission processing unit 129, and the high-frequency signal is convolved and frequency-converted into a predetermined transmission frequency band.

On the side that receives the signal transmitted by radio in this way (for example, a terminal device that receives a signal from a base station), the reception processing is performed by, for example, the configuration of FIG. 3 described in the first embodiment. By doing so, a signal of an arbitrary channel can be extracted and processed. That is, when extracting the signal of channel 1 or channel 2 from the multiplexed transmission signal in the state shown in FIG. 9, by extracting the symbol every four periods, the signal of that channel can be received. In the case of extracting the signal of No. 3, the signal of that channel can be received by extracting the symbol every two periods.

Here, although an example has been described in which communication is performed with a transmission rate of 32 kbps and a transmission rate of 64 kbps mixed in a band capable of transmitting up to 128 kbps, the present invention is not limited to this. That is, the transmission rate of each channel D [kbp
s] can be basically set as follows.

[0060]

## EQU2 ## Transmission rate D = M / 2 ^N [kbps] Here, N = 1, 2, 3 ＝ is a positive integer and M is the maximum transmission rate in the corresponding band.

Further, 96 kb described in the first embodiment is used.
Like ps, a rate having a value between the rates set by Expression 2 may be set.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. This embodiment is also an example in which the present invention is applied to a cellular wireless telephone system, and in this example, multiplex transmission is performed from a plurality of transmitters. For example, this corresponds to a case where multiple transmissions are simultaneously performed from a plurality of terminal apparatuses and collectively received at a base station.

FIG. 10 is a diagram showing a transmission configuration according to the present embodiment. Here, channel 1 to channel N
(N is any integer) information bit streams are individually obtained at terminals 141a to 141n of different transmitters. The transmitters basically have a common configuration. The configuration of a transmitter that processes a signal of channel 1 will be described. An information bit stream obtained at a terminal 141a is encoded by a coding unit 142a and encoded by interleaving. Perform processing. Each bit coded by the coding unit 142a is supplied to a symbol mapping unit 143a and mapped to a transmission symbol.

The transmission symbol generated by symbol mapping section 143a is transmitted to random phase shift section 144a.
Performs scramble processing by random phase shift (or other scramble processing), supplies the scrambled transmission symbols to an inverse Fourier transform (IFFT) processing unit 145a, and performs inverse fast Fourier transform arithmetic processing on the time axis. Is converted to a multicarrier signal in which subcarriers are arranged on the frequency axis. The signal converted by the inverse Fourier transform processing unit 145a is subjected to internal channel selection processing by an internal channel selection unit 146a, and the multicarrier signal subjected to the internal channel selection processing is supplied to a transmission processing unit 147a. The high-frequency signal is convolved and frequency-converted into a predetermined transmission frequency band, and the frequency-converted transmission signal is wirelessly transmitted from the antenna 148a.

FIG. 11 shows the configuration of the internal channel selection section 146a. A signal obtained at the terminal 151 from the preceding circuit is supplied to the symbol repetition unit 152, and a number of symbol repetition processes are performed according to the transmission rate at that time. For example, the maximum transmission rate in one transmission band here is 128 kb
In ps, it is assumed that the subcarrier interval on the transmission path of the multicarrier signal transmitted wirelessly is 4 kHz, and the transmission rate on one channel is 32 kbps. At this time, the preceding inverse Fourier transform processing unit 145a performs a process of converting the signal into a multicarrier signal having a subcarrier interval of 16 kHz.

The symbol repetition section 152 repeats the symbol component of this signal four times, and
Convert to interval signal. For example, as shown in FIG. 11, the waveform shown at the input of symbol repetition section 152 is converted to a waveform repeated four times by symbol repetition section 152. By repeating the inverse Fourier-transformed symbol stream by multiplex, an effect equivalent to inserting a null symbol into a subcarrier not used by the corresponding channel can be obtained.

The signal repeated in symbol repetition section 152 is multiplied in multiplier 153 by the offset frequency output from offset frequency generator 154. This multiplication causes a phase rotation in each symbol by the frequency offset of the corresponding channel. If the frequency offset of the corresponding channel is 0 Hz, multiplication by a constant is performed. That is, the channel to be used and the subcarrier assigned to it are determined based on the symbol sequence multiplied by the multiplier 153. The signal multiplied by the offset frequency is supplied to the windowing processing section 155, multiplied by transmission windowing data for each predetermined unit, and supplied from the terminal 156 to the transmission processing section 147a.

FIG. 12 shows an example of the state of a signal to be transmitted in each channel. Here, in the case where the maximum transmission rate in one transmission band is 128 kbps, and the data of this 128 kbps transmission rate is configured to be transmitted by a multicarrier signal with subcarriers at 4 kHz intervals,
Using one transmission band from four transmitters, data of a transmission rate of 32 kbps is transmitted from each transmitter to this one transmission band.
This shows a case where multiplex transmission is performed in a transmission band.

A, B, C, and D in FIG. 12 show transmission signals of channel 1, channel 2, channel 3, and channel 4 transmitted from each transmitter, respectively. The carrier is a multi-carrier signal at 16 kHz intervals. Here, the frequency position where the subcarrier exists in each channel is the channel 1
As shown in FIG. 12A, there is an interval of 16 kHz from the reference frequency fc.
As shown in FIG. 12C, there is an interval of 16 kHz from the frequency position shifted by 4 kHz from the frequency fc. As shown in FIG. 12C, channel 3 is at an interval of 16 kHz from the frequency position shifted by 8 kHz from the frequency fc. As shown in D of FIG.
The interval is 16 kHz from the frequency position shifted by 2 kHz.

By transmitting the signals of these channels by radio, subcarriers are arranged at intervals of 4 kHz on the radio transmission path as shown in FIG. 12E, and four channels are allocated to one transmission band. Will be multiplex-transmitted. In this case, as the fast inverse Fourier transform processing in the inverse Fourier transform processing unit provided in each transmitter, it is only necessary to convert a signal of a transmission rate of 32 kbps handled by the channel into a subcarrier group of 16 kHz width. The processing amount in the conversion processing unit can be made significantly smaller than the processing amount required at the subcarrier interval in the system.

Here, an example in which a signal having a transmission rate of 32 kbps is communicated has been described. For example, when a signal having a transmission rate of 64 kbps is communicated in the same transmission band,
The operation is performed by the inverse Fourier transform processing unit having a scale suitable for the communication at that rate (ie, twice the number of samples is output as in the case of communication at 32 kbps), and the symbol is repeated twice in the internal channel selection unit. A transmission signal can be generated by the same processing at any transmission rate. In this case, the processing circuit provided in each transmitter (terminal device) only needs to include an inverse Fourier transform processing circuit having a capacity corresponding to the transmission rate at which the transmission is performed by the device. There is no need to have the ability to generate multicarrier signals at subcarrier intervals specified by the band, and the configuration of the terminal device can be simplified.

Further, for example, by simultaneously performing the null symbol insertion processing as described in the above-described first embodiment and performing the processing corresponding to the change in the transmission rate,
It is possible to cope with a case where the transmission rate is lower.

Next, the signal thus multiplexed and transmitted is
For example, FIG. 13 shows an example of a configuration in which a base station collectively receives data. The reception processing unit 162 to which the antenna 161 is connected receives a signal in a predetermined transmission frequency band and converts the signal into a baseband signal. The converted baseband signal is
After being supplied to the windowing processing unit 163 and multiplying the signal of each predetermined unit by the windowing data for reception, the Fourier transform (FF)
T) The signal is supplied to the processing unit 164, and the subcarriers arranged on the frequency axis are converted into symbol streams arranged on the time axis. Here, the conversion process is a process of converting all the subcarriers arranged in the received transmission band.

The converted symbol stream is subjected to a descrambling process which is the reverse of the scrambling process at the time of transmission by the random phase shift unit 165. The descrambled symbol stream is subjected to a process of separating the symbols multiplexed in one transmission band for each channel by a separation circuit (demultiplexer) 166. The symbol streams separated for each channel are supplied to bit extraction units 167a, 167b ‥‥ 167n for each channel,
A bit extraction process is individually performed for each channel to obtain a reception bit stream, and the reception bit stream is decoded by the decoding units 168a, 168b ‥‥ 168 for each channel.
n, and individually decodes for each channel to obtain an information bit stream for each channel at terminals 169a, 169b９169n for each channel.

FIG. 14 is a diagram simply showing the concept of the processing in the separation circuit 166. In this case, for example, four channels of channel 1 to channel 4 multiplexed in one system symbol stream.
It separates the symbol stream of the channel. Switch contact 166m constituting separation circuit 166
Are periodically switched to sequentially supply the multiplexed symbol streams obtained as described above to the four terminals 166a to 166d for each symbol. By performing such switching, the symbol stream of channel 1 is obtained at terminal 166a, the symbol stream of channel 2 is obtained at terminal 166b, the symbol stream of channel 3 is obtained at terminal 166c, and the
Are obtained at a terminal 166d.

FIG. 15 is a diagram showing an example of this separation state. For example, a signal shown in FIG. 15A is a symbol stream obtained by receiving a signal of one transmission band in which four-channel signals are multiplexed. In the symbols arranged at regular time intervals, symbols of four channels are mixed. Here, by switching the contact 166m of the switch constituting the separation circuit 166 in order for each symbol, B, FIG.
As shown in C, D, and E, the symbols of each channel are separated and output.

By configuring the receiver in this manner, signals of a plurality of channels multiplexed in one transmission band can be received at a time.

Next, a fifth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. This embodiment is also an example in which the present invention is applied to a cellular wireless telephone system, and in this example, an arbitrary channel in a signal multiplexed and transmitted in one transmission band in the processing in the above-described embodiment. Is received. For example, this corresponds to a case where an arbitrary channel is received by a terminal device from signals multiplexed and transmitted from a base station at the same time.

First, the signal received in this example will be described. Here, it is assumed that four channels of a rate of 32 kbps are multiplexed in a bandwidth capable of transmitting a rate of a maximum of 128 kbps in one transmission band. The subcarrier interval on the transmission line is 4 kHz (that is, the modulation time of one symbol is 250 μsec = 1/4 kHz).

FIG. 16 is a diagram showing a receiving configuration according to the present embodiment. Here, the reception processing unit 172 to which the antenna 171 is connected receives a signal in a predetermined transmission frequency band and converts it into a baseband signal. After the desired channel is selected by the channel selection unit 173, the converted baseband signal is supplied to the multicarrier processing unit 174 with the reception signal of the selected channel, and is arranged on the frequency axis by Fourier transform processing or the like. Converted subcarriers into symbol streams arranged on the time axis.
It should be noted that other processes required for multicarrier processing such as windowing processing and random phase shift are also executed by the multicarrier processing unit 174.

The converted symbol stream is supplied to a bit extracting section 175 to extract coded bits, and the extracted bit data is supplied to a decoding section 176 for decoding.
Get to 77.

FIG. 17 is a diagram showing a configuration example of the channel selection unit 173. Here, as the baseband signal supplied to the terminal 181 from the preceding reception processing unit, a signal in which subcarriers are arranged at intervals of 4 kHz on the frequency axis is input for 250 μsec. The signal obtained at the terminal 181 is supplied directly to the selector 181a, and is also delayed and supplied to the selector 181a via the delay circuit 181b, and the symbol of the signal is repeatedly processed by the selection by the selector 181a.

The output of this selector 181a is
82, and the delay circuit 183 sets the time of 1/2 ¹ of the modulation time of one symbol (that is, 125 times in this case).
The signal delayed by (.mu.sec) is supplied to the subtractor 182, and the difference between the two signals is extracted. The difference signal is further supplied directly to the subtractor 184, and is delayed by a delay circuit 185 for a period of 1/4 (= 1/2 ² ) of the modulation time of one symbol (that is, 62.5 μsec in this case). The subtracted signal is supplied to a subtractor 184, the difference between the two signals is extracted, and the difference signal is obtained at a terminal 191 via a multiplier 195.
Further, the output signal of the subtractor 182 is directly supplied to the adder 186, the signal delayed by the delay circuit 185 is supplied to the adder 186, and the added signal of both signals is supplied to the terminal 192 via the multiplier 196. Is obtained.

The signal obtained by subjecting the signal obtained at terminal 181 to symbol repetition processing by selector 181a and delay circuit 181b is supplied to adder 187,
The signal delayed by the delay circuit 183 is supplied to the adder 187, and an addition signal of both signals is obtained. This addition signal is further directly supplied to a subtracter 188 and is further delayed by a delay circuit 189 to １ ／ (= 1) of the modulation time of one symbol.
/ 2 ² ) is supplied to the subtractor 188, the difference between the two signals is extracted, and the difference signal is passed through the multiplier 197 to the terminal 19.
3 is obtained. The output signal of the adder 187 is directly supplied to the adder 190, the signal delayed by the delay circuit 189 is supplied to the adder 190, and the added signal of both signals is supplied to the terminal 194 via the multiplier 198. Is obtained. In each of the multipliers 195, 196, 197, and 198, offset frequency correction signal generators 195a, 196a,
The correction signals from 197a and 198a are multiplied. This offset frequency correction processing will be described later.

The channel selector 17 configured as described above
The processing state in 3 will be described with reference to FIG. First,
As shown in FIG. 18A, a signal obtained by sequentially arranging subcarriers of channels 1 to 4 at intervals of 4 kHz as a signal obtained at terminal 181 is input for 250 μsec. Here, the first 125 μs and the second 125 μs of this signal
For each second, the result of subtraction by the subtractor 182 and the result of addition by the adder 187 are generated. As the output of the adder 187, the number of subcarriers becomes 1/2 ¹ from the original signal, and as shown in FIG.
Only the odd-numbered subcarriers of channel 1 and channel 3 are included. The output of the adder 187 is further subtracted by the subtractor 188 from the delayed signal,
And the sum of the delay signal and the sum is generated. Adder 19
The signal added with 0 is only the subcarrier of the channel 1 signal as shown in FIG. 18C. The signal subtracted by the subtractor 188 is only the subcarrier of the channel 3 signal as shown in FIG.

The output of the subtracter 182 has the number of subcarriers halved from the original signal, and includes only the even-numbered subcarriers of channel 2 and channel 4, as shown in FIG. From the output of the subtracter 182, the one added to the delay signal by the adder 186,
A subtracted signal is generated by the subtractor 184. The signal added by the adder 186 is only the subcarrier of the channel 2 signal as shown in FIG. The signal subtracted by the subtracter 184 is only the subcarrier of the channel 4 signal as shown in FIG.

In this way, the terminals 191, 192, 19
3, 194, the signal obtained by FFT
Processing (fast Fourier transform processing) is performed to extract subcarriers. As shown in D, F, and G in FIG. 18, offset frequencies are convolved in signals of channels 2 to 4. It is in a state. Specifically, assuming that the subcarrier interval of the multiplexed signal is fs [Hz], channel 2 has fs [Hz] and channel 3 has 2 fs [H
z], channel 4 has an offset frequency of 3 fs [Hz]. So, to remove these offsets,
Multipliers 195, 196, 197, and 198 multiply by a sine wave having a negative offset frequency.
1, 192, 193, and 194. Specifically, the output is obtained by multiplying the signal of −fs [Hz] for channel 2, the signal of −2 fs [Hz] for channel 3, and the signal of −3 fs [Hz] for channel 4.

This processing is performed by generating a signal of exp (−j2π (i / M × 1)) in the correction signal generator 196 a in the channel 2 and multiplying the signal by the multiplier 196. . In the channel 3, the correction signal generator 19
At 7a, a signal of exp (-j2π (i / M × 2)) is generated,
This is performed by multiplying the signal by a multiplier 197. Also, in channel 4, ex.
This is performed by generating a signal of p (−j2π (i / M × 3)) and multiplying the signal by the multiplier 195. Here, M shown as the correction signal is the number of symbols input to the channel selection means 173 within 250 μsec, and i is a suffix indicating the number of the input symbol. The signals obtained at the terminals 191, 192, 193, and 194 from which the offset frequency has been removed in this manner are observed and observed on the frequency axis.
As shown on the right side of D, F, and G, the offset frequency is wiped off, and the sub-carrier of any channel can be extracted by the same FFT circuit.

Thus, the channel selection section 173
Then, the subcarriers for each channel are separated, and the circuits after the channel selection unit 173 process only the subcarriers of the channels that need to be received, so that an information bit stream of the corresponding channel can be obtained.

By the way, the channel selector shown in FIG. 17 is configured to separate the signals of all four channels multiplexed and transmitted. However, when only one channel signal is required, For example, the channel selection unit 173 'shown in FIG. That is, the terminal 20
1 is subjected to symbol repetition processing using a selector 201a and a delay circuit 201b, and then supplied to an arithmetic unit 202. ^The signal delayed by ^one time is supplied to the arithmetic unit 202. Arithmetic unit 20
Reference numeral 2 denotes a circuit for performing one of the addition processing and the subtraction processing under the control of the control unit 207. The output of the arithmetic unit 202 is directly supplied to the arithmetic unit 204, and is output by the delay circuit 205 to １ ／ (= 1/1) of one modulation time.
The signal delayed by 2 ² ) is supplied to the arithmetic unit 204. The calculation unit 204 is a circuit that performs one of the addition process and the subtraction process under the control of the control unit 207. The arithmetic output of the arithmetic unit 204 is supplied to a terminal 206 after removing an offset frequency by multiplication with a sine wave by a multiplier 208, and is supplied to a subsequent circuit from the terminal 206. The offset frequency to be corrected by the multiplier 208 is determined by the control of the control unit 207. With this configuration, the addition processing or the subtraction processing in the calculation unit 202 and the calculation unit 204 is controlled by the control unit 207, and the selection processing state for each channel in the channel selection unit 173 illustrated in FIG. In this state, only the subcarriers of the desired channel can be extracted from the multiplexed four-channel signals.

For example, when signals of two channels are multiplexed in one transmission band (for example, signals of a transmission rate of 64 kbps are multiplexed in two channels),
A channel selector for extracting a signal of each channel can be constituted by, for example, a channel selector 173 ″ shown in Fig. 20. That is, a received signal (baseband signal) obtained at a terminal 211 is converted into a selector 211a and a delay circuit 211.
After the symbol repetition process is performed using b, the signal is supplied to the arithmetic unit 212, and the signal delayed by 1/2 ¹ of one modulation time by the delay circuit 213 is calculated by the arithmetic unit 212.
To supply. The operation unit 212 is a circuit that performs one of an addition process and a subtraction process under the control of the control unit 215. The arithmetic output of the arithmetic unit 212 is supplied to a terminal 214 after the offset frequency is removed by a multiplier 216 by multiplication with a sine wave, and then supplied to a subsequent circuit from the terminal 214. The offset frequency to be corrected by the multiplier 216 is determined by the control of the control unit 215.
With this configuration, it is possible to extract only the subcarrier of one of the multiplexed two-channel signals from the multiplexed two-channel signal under the control of the addition unit or the subtraction unit 215 in the arithmetic unit 212. Can be.

For example, when the maximum transmission rate in one transmission band is 128 kbps, the maximum transmission rate is 64 kbps.
When a terminal device that wants to support up to ps performs reception at a low rate such as 8 kbps, a channel selection unit corresponding to the maximum transmission rate (64 kbps) at the terminal device is provided, and a multicarrier signal of 64 kbps is provided. After converting the processed subcarriers on the frequency axis into a symbol stream on the time axis, a process of selecting a desired channel from the symbol stream may be performed.

On the other hand, a low-rate-only receiver that only supports 8 kbps, for example, has an operation unit 2 shown in FIG.
04 and the processing means corresponding to the delay circuit 205 are serially connected and the same processing is performed, so that the number of output symbols of the channel selection means 173 is reduced to ^{N N} (N (The number of stages of the processing means). The number of stages inside the channel selection means can be selected arbitrarily, and this value is determined by the maximum transmission rate supported by the receiver. Note that the delay amount at each stage is 1/2 ^j (j indicates the number of stages).

In this embodiment, an example of a cellular radio telephone system has been described. However, a receiver for selecting and receiving a desired channel from signals multiplexed and transmitted in this manner is a multicarrier signal. Therefore, the present invention can be applied to receivers for other systems such as DAB (Digital Audio Broadcasting) in which broadcast signals of a plurality of channels are multiplexed and transmitted. By applying the present invention to the receiver, it is only necessary to provide, as the Fourier transform means provided in the receiver, one capable of performing conversion processing of only one channel of subcarriers. The configuration of the receiver can be simplified as compared with the case where the processing capability is provided.

Next, a sixth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. The present embodiment is an example in which the present invention is applied to a cellular radio telephone system. When a plurality of channels are multiplexed and transmitted in one transmission band, any one of the multiplexed channels is used as a pilot channel. is there.

FIG. 21 is a diagram showing a transmission configuration according to the present embodiment. Here, channel 1 to channel N
(N is any integer) information bit streams of the number N of channels are obtained at the terminals 221a to 221n,
It is assumed that a bit stream of a pilot channel is obtained at a terminal 221p. Here, a predetermined known signal is supplied to the terminal 221p as pilot channel data. In addition to this known signal, some control data (for example, an ID for recognizing a base station)
Etc.) may be transmitted. Here, channels other than the pilot channel (channels 1 to 5)
Channel N) is called a traffic channel.

The information bit streams of the respective traffic channels obtained at the terminals 221a to 221n are bit streams of the same transmission rate here, and are supplied to different coding sections 222a to 222n to perform coding such as coding and interleaving. Perform the processing individually. Coding units 222a to 222n
Are supplied to different symbol mapping units 223a to 223n, respectively, and individually mapped to transmission symbols for each channel. In addition, the bit stream of the pilot channel obtained at the terminal 221p is directly supplied to the symbol mapping unit 223p and mapped to a transmission symbol.

Symbol mapping unit 2 for each channel
The transmission symbols generated at 23a to 223n and 223p are supplied to a mixing circuit (multiplexer) 224,
Mixed into the symbol stream of the system. This mixing circuit 2
The configuration of the mixing process at 24 may be the same as the configuration of the mixing circuit 124 described with reference to FIG. 6 in the second embodiment, for example. The transmission symbols mixed by the mixing circuit 224 are subjected to processing such as scrambling processing, inverse Fourier transform processing, and windowing processing by a multicarrier processing unit 225 to form a multicarrier signal composed of subcarriers arranged on the frequency axis. Then, the generated multicarrier signal is supplied to the transmission processing unit 226, the high-frequency signal is convolved and frequency-converted into a predetermined transmission frequency band, and the frequency-converted transmission signal is wirelessly transmitted from the antenna 227.

FIG. 23 shows an example of a multiplexed state in one transmission band in the case of a channel configuration including a pilot channel as described above. Here, three traffic channels of channels 1 to 3 and
This is an example in which one pilot channel is multiplexed, and subcarriers of each channel are arranged in order.

Next, a configuration for receiving a signal transmitted in this manner is shown in FIG. The reception processing unit 232 to which the antenna 231 is connected receives a signal in a predetermined transmission frequency band and converts the signal into a baseband signal. The converted baseband signal is supplied to the first and second channel selection units 2
33a and 233b. The first channel selection unit 233a performs a process of selecting a subcarrier of a traffic channel to be received. The second channel selection unit 233b performs a process of selecting a subcarrier of a pilot channel. Each channel selection unit 233
a and 233b are separately supplied to the multicarrier processing units 234a and 234b, respectively.
A process of converting a subcarrier on the frequency axis into a symbol stream on the time axis by Fourier transform processing or the like is performed. The symbol stream of a predetermined traffic channel obtained by the multi-carrier processing unit 234a is supplied to a channel equalizer 235.

The equalizer 235 estimates the state of the transmission path based on the state of the known signal received on the pilot channel, and based on the estimated state of the transmission path, performs equalization processing on the transmission path of the symbol received on the traffic channel. And performs synchronous detection of the equalized symbol. The detected symbol is supplied to a bit extraction unit 236 to extract coded bits, and the extracted bit data is supplied to a decoding unit 237 to be decoded, and a decoded information bit stream is obtained at a terminal 238. The data received on the pilot channel is supplied to a control unit of a terminal device (not shown), and a control process is performed based on the data.

First and second channel selector 233a
And 233b are configured, for example, as shown in FIG.
That is, in the first channel selection unit 233a, the signal obtained at the terminal 241 from the circuit at the previous stage is added to the selector 241a.
After performing symbol repetition processing using the delay circuit 241b and the delay circuit 241b, the signal is supplied to the calculation unit 242, and a signal delayed by 1/2 ¹ of the modulation time by the delay circuit 243 is supplied to the calculation unit 242. The calculation unit 242 is a circuit that performs one of the addition process and the subtraction process under the control of the control unit 247. The output of the operation unit 242 is directly supplied to the operation unit 244 and the delay circuit 2
A signal which is delayed by 演算 (= １ ／ ² ) of one modulation time by 45 is supplied to the arithmetic unit 244. Arithmetic unit 244
Is a circuit for performing one of the addition processing and the subtraction processing under the control of the control unit 247. The arithmetic output of the arithmetic unit 244 is supplied to a subsequent circuit from a terminal 246 after a multiplier 248 multiplies the sine wave specified by the control unit 247 to remove the offset frequency.

The second channel selection unit 233b performs symbol repetition processing using the selector 251a and the delay circuit 251b on the signal obtained from the circuit at the preceding stage to the terminal 251 and then supplies the signal to the calculation unit 252. The signal delayed by 1/2 ¹ of one modulation time by the delay circuit 253 is supplied to the arithmetic unit 252. Arithmetic unit 25
Reference numeral 2 denotes a circuit that performs one of an addition process and a subtraction process under the control of the control unit 247. The output of the arithmetic unit 252 is directly supplied to the arithmetic unit 254, and the output of the delay circuit 255 is １ ／ (= 1/1) of one modulation time.
The signal delayed by 2 ² ) is supplied to the arithmetic unit 254. The calculation unit 254 is a circuit that performs one of the addition process and the subtraction process under the control of the control unit 247. The calculation output of the calculation unit 254 is supplied to a subsequent circuit from a terminal 256 after the offset frequency is removed by multiplying the sine wave specified by the control unit 247 by the multiplier 257. With this configuration, based on the control of the control unit 247, the first channel selection unit 2
In 33a, a subcarrier of a desired traffic channel can be extracted, and in another channel selector 233b, a subcarrier of a pilot channel can be extracted.

With this configuration, it is possible to perform transmission path estimation based on a known signal (pilot signal) transmitted on a pilot channel, and to perform transmission and reception by synchronous detection. As a result, better transmission characteristics can be obtained than when differential modulation is performed. In addition, for channels transmitted from the same base station, since they are basically orthogonal to each other, they are not interference sources, and only signals transmitted from other base stations are considered as interference. Affect. In such a case, since a pilot signal is transmitted from each base station, it is also possible to cancel interference by using the signal and applying an adaptive array antenna or the like. In this embodiment, an example in which four channels are multiplexed has been described. However, similar to the examples described in the other embodiments, the basic multiplexing number is set to 2 ^N and various multiplex communications are performed. The configuration can be performed.

In each of the embodiments described so far, the processing within one modulation unit has been described. However, in practice, this processing is repeatedly executed on the time axis. Therefore, by changing the correspondence between the logical channel and the physical channel in units of one modulation time, it is possible to perform communication using all the frequencies of the system band even in the channel of the low transmission rate. FIG. 25 shows an example of this case. The time slots TS1, TS2, T
S3} and logical channel CH for each time slot
The arrangement of the subcarriers 1 to CH4 is changed. Here, it is a periodic change with four time slots as one cycle. The correspondence between the logical channel and the physical channel may be obtained by using a hopping pattern in an existing frequency hopping system.

In each of the above-described embodiments, only processing within one transmission band has been described. However, when a plurality of transmission bands are prepared, it is called frequency hopping for exchanging frequency bands. Processing may be performed. FIG. 26 shows an example of this case. Here, when six transmission bands F1 to F6 (one transmission band corresponds to one transmission band in each embodiment) are prepared.
For example, in the communication time Ta, the bands F1,
The array of F2, F3, F4, F5, and F6 is used, and the array of bands is changed for each of the communication times Tb, Tc, and Td and a predetermined time unit. Also in this case, it is changed periodically. By performing frequency hopping in this way, a greater frequency diversity effect can be obtained. Further, a process of changing the arrangement of subcarriers in each band shown in FIG.
The frequency hopping process for each band shown in FIG. 26 may be used together.

Further, in each of the above-described embodiments, details of the modulation / demodulation processing when transmission is performed by using a multicarrier signal are not described. However, as described in each of the embodiments, the subcarriers on the frequency axis are used. Is assigned to one channel for each of a plurality of channels, differential modulation (phase modulation or amplitude modulation) is performed between adjacent ones of subcarriers assigned to the channel, and then transmitted. A demodulation process (ie, a differential demodulation process between adjacent subcarriers assigned to the channel) may be performed. This process can be applied to uplink communication from a terminal device to a base station in, for example, a wireless telephone system such as a cellular system. Also, the present invention can be applied to downlink communication from a base station to a terminal device.

By performing such processing, for example, when the terminal apparatus is moving at a high speed, and when this processing is not performed, the fading correlation between symbols becomes low, and the characteristics may be degraded. , By performing the processing of this example,
The correlation between symbols increases, and differential demodulation that can be performed with simpler processing than synchronous detection enables good reception and good transmission independent of the moving speed of the terminal device.

Further, when subcarriers on the frequency axis are assigned to one channel for each of a plurality of channels, regardless of whether each subcarrier is assigned to the same channel, Transmission may be performed after performing differential modulation (phase modulation or amplitude modulation), and the receiving side may perform reverse demodulation processing (that is, differential demodulation processing between adjacent subcarriers). For this process,
For example, in a wireless telephone system such as a cellular system,
The present invention can be applied to uplink communication from a terminal device to a base station.
Also, the present invention can be applied to downlink communication from a base station to a terminal device.

Note that each of the differential modulation processing and the differential demodulation processing described here can be applied even when the number of subcarriers is not 2 to the Nth power described in each embodiment.

In each of the above-described embodiments, an example in which the present invention is applied mainly to a radio telephone system or DAB (digital audio broadcasting) has been described. However, other various transmission systems multiplex-transmitted by the same multicarrier signal are also applicable. Of course, it can be applied. The values such as the transmission rate, frequency interval, and multiplex number shown in each embodiment are
This is shown as an example, and it goes without saying that other values can be applied.

[0112]

According to the communication method described in claim 1,
In the transmission signal in which each channel is multiplexed into a multi-carrier signal, transmission symbols of each channel are arranged at predetermined frequency intervals, so that it is easy to form a multiplexed transmission signal on the transmission side. In addition, it is possible to easily perform the receiving process by extracting only the signal of each channel, and to simplify the configuration of the receiving side. Further, when applied to wireless communication, broadband communication is performed at wide subcarrier intervals, so that it is possible to obtain a frequency diversity effect.

According to the communication method described in claim 2, in the invention described in claim 1, the value of N is variably set according to the bit rate of data to be transmitted, so that data having different bit rates are mixed. It can be easily transmitted.

According to the communication method described in claim 3, in the invention described in claim 1, one of the downlink channels transmitted from the base station is reserved as a pilot channel, the remaining channels are used as traffic channels, and The station transmits a known signal on a pilot channel, and the terminal device performs an equalization process on a transmission path of a symbol received on a traffic channel using a symbol received on the pilot channel, and performs the equalization process. By performing the synchronous detection of the symbol, the equalization processing of the transmission signal can be easily and satisfactorily performed.

According to the communication method described in claim 4, in the invention described in claim 1, the multiplexed signal is efficiently spread by frequency-hopping the transmitted signal in channel units or frequency units. , And a good transmission state can be secured.

According to the communication method of the present invention, the channel arrangement is a multicarrier signal using a predetermined number of subcarriers and differential modulation between adjacent subcarriers of each channel. Is performed, transmission processing and reception processing can be performed using only signals of each channel.

According to the communication method described in claim 6, in the invention described in claim 5, instead of performing differential modulation between adjacent subcarriers assigned to each channel on the transmission side, Instead of performing differential modulation between adjacent subcarriers on the frequency axis and performing differential demodulation between adjacent ones of the subcarriers allocated to each channel on the receiving side, adjacent subcarriers on the frequency axis are used. By performing differential demodulation between carriers, transmission processing can be performed by processing based on the arrangement of subcarriers on the frequency axis.

According to the transmitter of the present invention, the transmission symbols of each channel are arranged at predetermined frequency intervals, a multicarrier signal in which each channel is multiplexed is transmitted, and the transmission symbols of each channel are fixed. And a transmission signal that can be easily multiplexed by simple processing can be formed.

According to the transmitter of the eighth aspect, in the invention of the seventh aspect, data of different bit rates are mixed by setting the value of N variably according to the bit rate of the data to be transmitted. It can be easily transmitted.

According to the transmitter of the ninth aspect, in the invention of the seventh aspect, after individually generating transmission symbols of a plurality of channels, the symbols of each channel are arranged for each symbol and a multiplexed symbol sequence is generated. Is generated, multi-carrier signal generation processing is performed collectively on the generated multiplex symbol sequence, and transmission processing is performed collectively on a plurality of channels. I can do it.

According to the transmitter set forth in claim 10, in the invention set forth in claim 7, a transmission symbol is generated, and the generated transmission symbol is extracted as a signal on the time axis, and then is allocated to the own station. By performing the process of convolving the frequency offset corresponding to the changed channel, the process of transmitting at the target frequency can be favorably performed with a simple configuration.

According to the transmitter described in claim 11, in the invention described in claim 7, a known signal is transmitted using one of a plurality of transmitted channels as a pilot channel, and the remaining channels are transmitted. By performing transmission processing as a traffic channel, transmission control can be favorably performed based on a known signal transmitted on a pilot channel.

According to the transmitter of the twelfth aspect, in the invention of the seventh aspect, there is provided a frequency hopping means for frequency hopping the generated multicarrier signal in channel units or in predetermined frequency band units. , A frequency / interference diversity effect is obtained, and transmission is improved.

According to the receiver of the present invention, the transmission symbols of each channel are arranged at a predetermined frequency interval, and a multicarrier signal in which each channel is multiplexed can be received. , A signal of a desired reception channel can be obtained, and a signal of a desired channel can be easily obtained from a multiplexed and transmitted signal.

According to the receiver of the fourteenth aspect, in the invention of the thirteenth aspect, out of all the symbol groups transmitted in the bandwidth used for communication from the received signal, the transmitting side transmits the symbol. By extracting only the symbols of the communication channel that is present and supplying the extracted symbols to the channel decoder for decoding, reception processing of only the required symbols can be efficiently performed.

According to the receiver set forth in claim 15, in the invention set forth in claim 13, the received signal is sampled at a sample rate determined by the bandwidth of the received signal, and the sampled symbols are added to each other or added. By subtracting, a desired reception channel is selected, and the number of symbols output to the subsequent stage is reduced,
The required minimum sample rate determined by the maximum bit rate at the time of reception is set, and the received data of the required number of symbols at the required minimum sample rate is received. Can get better.

According to the receiver set forth in claim 16, in the invention set forth in claim 15, the reception processing means for receiving and processing the received data has a processing capability determined by the maximum bit rate, By extracting only desired bits when performing communication at a low bit rate, the amount of data processing during communication at a low bit rate can be reduced.

According to a seventeenth aspect of the present invention, in the thirteenth aspect of the present invention, the receiver according to the thirteenth aspect further comprises a pilot channel reception processing means and a traffic channel reception processing means. The traffic channel reception symbol transmission path is equalized by the traffic channel reception symbol processing means using the known signal symbols obtained by the traffic channel reception symbol transmission path. , And good reception processing can be performed.

According to the eighteenth aspect of the present invention, the frequency hopping means according to the thirteenth aspect of the present invention includes the frequency hopping means for frequency hopping the received signal in channel units or predetermined frequency band units. The received transmission signal can be properly received.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a transmission configuration example according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a null symbol insertion and extraction state according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a receiving configuration example according to the first embodiment of the present invention.

FIG. 4 shows a process according to the first embodiment of the present invention performed by TDM.
It is explanatory drawing which shows the example applied to the A system.

FIG. 5 is a block diagram illustrating a transmission configuration example according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram illustrating an example of a mixing circuit according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram illustrating an example of a mixed state according to the second embodiment of the present invention.

FIG. 8 is a block diagram illustrating a transmission configuration example according to a third embodiment of the present invention.

FIG. 9 is an explanatory diagram illustrating an example of a mixed state according to the third embodiment of the present invention.

FIG. 10 is a block diagram illustrating a transmission configuration example according to a fourth embodiment of the present invention.

FIG. 11 is a block diagram illustrating a configuration example of an internal channel selection unit according to a fourth embodiment of the present invention.

FIG. 12 is an explanatory diagram showing a subcarrier arrangement example according to a fourth embodiment of the present invention.

FIG. 13 is a block diagram illustrating a receiving configuration example according to a fourth embodiment of the present invention.

FIG. 14 is a configuration diagram illustrating an example of a separation circuit according to a fourth embodiment of the present invention.

FIG. 15 is an explanatory diagram illustrating an example of a separated state according to the fourth embodiment of the present invention.

FIG. 16 is a block diagram showing a receiving configuration example according to a fifth embodiment of the present invention.

FIG. 17 is a configuration diagram illustrating an example of a channel selection unit according to a fifth embodiment of the present invention.

FIG. 18 is an explanatory diagram showing a processing example in a channel selection unit according to a fifth embodiment of the present invention.

FIG. 19 is a configuration diagram illustrating another example of the channel selection unit.

FIG. 20 is a configuration diagram showing still another example of the channel selection unit.

FIG. 21 is a block diagram illustrating a transmission configuration example according to a sixth embodiment of the present invention.

FIG. 22 is a block diagram illustrating a receiving configuration example according to a sixth embodiment of the present invention.

FIG. 23 is an explanatory diagram showing an example of arrangement of transmission symbols according to the sixth embodiment of the present invention.

FIG. 24 is a configuration diagram illustrating an example of a channel selection unit according to a sixth embodiment of the present invention.

FIG. 25 is an explanatory diagram showing an example of subcarrier arrangement by other processing in each embodiment of the present invention.

FIG. 26 is an explanatory diagram showing a frequency hopping process applied to each embodiment of the present invention.

FIG. 27 is a block diagram illustrating an example of a conventional DS-CDMA transmission process.

FIG. 28 is a block diagram illustrating an example of a conventional DC-CDMA reception process.

FIG. 29 is an explanatory diagram showing a multiplexing example in a conventional TDMA system.

FIG. 30 is a block diagram illustrating an example of a conventional OFDM transmission process.

FIG. 31 is a block diagram illustrating a reception process example of the conventional OFDM system.

[Explanation of symbols]

103, 123a to 123n, 133a to 133d, 1
43a to 143n, 223a to 223n, 223p: Symbol mapping processing unit, 104: Null symbol insertion unit, 105, 125, 144a to 144n: Random phase shift unit, 106, 126, 145a to 145n: Inverse Fourier transform processing unit (IFFT) Processing unit), 107, 12
7: guard time addition unit, 108, 128: windowing processing unit, 109, 129, 147a to 147n, 226: transmission processing unit, 112, 162, 172, 232: reception processing unit, 113, 163: windowing processing unit , 114,164 ...
Fourier transform processing unit (FFT processing unit), 115: descrambling unit, 116: symbol selecting unit, 117, 167
a to 167n, 175, 236... bit extraction unit, 12
4, 134, 224 ... mixing circuit, 146a to 146n,
173, 173 ', 173 ", 223a, 223b: channel selector, 165: random phase shifter, 16
6. Separation circuit, 174, 225, 234a, 234b
Multi-carrier processing unit, 235 ... Channel equalizer

Claims (19)

[Claims] 1. A method for setting a plurality of channels in a predetermined band, performing communication on each of the set channels by using a multicarrier signal in which transmission symbols are dispersed among a plurality of subcarriers, and transmitting symbols on each channel. A communication method in which the arrangement on the frequency axis is arranged at every Nth power of 2 (N is a positive arbitrary number) with respect to a reference frequency interval. 2. The communication method according to claim 1, wherein the communication is a wireless communication. 3. The communication method according to claim 1, wherein the value of N is variably set according to a bit rate of data to be transmitted. 4. The communication method according to claim 1, wherein the method is applied to communication between a base station and a terminal device, wherein one downlink channel transmitted from the base station is reserved as a pilot channel, and the remaining channels are reserved. The base station transmits a known signal on the pilot channel, and the terminal device performs, using the symbols received on the pilot channel, an equalization process of the transmission path of the symbols received on the traffic channel. Communication method for performing synchronous detection of the symbol subjected to the equalization processing. 5. The communication method according to claim 1, wherein the transmitted signal is frequency-hopped in channel units or frequency units. 6. A plurality of channels are set in a predetermined band, communication on each set channel is performed by a multi-carrier signal in which transmission symbols are distributed to a plurality of sub-carriers, and sub-channels allocated to each channel are set. Using a predetermined number of subcarriers as carriers, perform differential modulation between adjacent subcarriers assigned to each channel, and then transmit.Receiver performs differential demodulation between adjacent ones. Communication method to do. 7. The communication method according to claim 6, wherein, on the transmitting side, instead of performing differential modulation between adjacent subcarriers assigned to each channel, the subcarriers between adjacent subcarriers on the frequency axis are transmitted. Communication that performs differential modulation on the receiving side and performs differential demodulation between adjacent subcarriers on the frequency axis instead of performing differential demodulation on adjacent subcarriers assigned to each channel on the receiving side. Method. 8. A multi-carrier signal in which transmission symbols are dispersed in a plurality of subcarriers is generated, and the arrangement of transmission symbols in one channel of the multi-carrier signal on a frequency axis is determined by a reference frequency interval. A transmitter that transmits the generated multicarrier signal as a predetermined channel among a plurality of channels set in a predetermined band, every 2 N (where N is a positive arbitrary number). 9. The transmitter according to claim 8, wherein the value of N is variably set according to a bit rate of data to be transmitted. 10. The transmitter according to claim 8, wherein after individually generating transmission symbols of a plurality of channels, a symbol sequence of each channel is arranged for each symbol to generate a multiplexed symbol sequence. A transmitter that performs multi-carrier signal generation processing collectively in rows and performs transmission processing collectively on multiple channels. 11. The transmitter according to claim 8, wherein a transmission symbol is generated, and the generated transmission symbol is extracted as a signal on a time axis, and then a frequency offset corresponding to a channel allocated to the own station is calculated. A transmitter that performs convolution processing. 12. The transmitter according to claim 8, wherein one of the plurality of channels to be transmitted is used as a pilot channel to transmit a known signal, and the remaining channels are transmitted as traffic channels. 13. The transmitter according to claim 8, further comprising frequency hopping means for frequency hopping the generated multicarrier signal in channel units or in predetermined frequency band units. 14. A multi-carrier signal in which transmission symbols are dispersed among a plurality of subcarriers is received, and transmission symbols received in one channel are placed at every Nth power of a reference frequency interval (N is a positive number). Any number of
Receiver that performs reception processing at frequency intervals of. 15. The receiver according to claim 14, wherein only symbols of a communication channel transmitted by the transmitting side are extracted from a group of symbols transmitted in a bandwidth used for communication from a received signal. A receiver that supplies the extracted symbols to a channel decoder and decodes them. 16. The desired reception channel according to claim 14, wherein the reception signal is sampled at a sample rate determined by a bandwidth of the reception signal, and the sampled symbols are added or subtracted from each other. To reduce the number of symbols to be output in the subsequent stage to the required minimum sample rate determined by the maximum bit rate at the time of reception.Receive data with the required number of symbols at the required minimum sample rate. Receiver. 17. The receiver according to claim 16, wherein the reception processing means for receiving and processing the received data has a processing capability determined by a maximum bit rate, and performs communication at a bit rate lower than the maximum bit rate. A receiver that extracts only the desired bits when performing 18. The receiver according to claim 14, further comprising: a pilot channel reception processing unit; and a traffic channel reception processing unit, wherein a known signal symbol received by the pilot channel reception processing unit is used. A receiver for performing, on the traffic channel reception processing means, an equalization process of a transmission path of a reception symbol of the traffic channel. 19. The receiver according to claim 14, further comprising frequency hopping means for frequency hopping the received signal on a channel basis or on a predetermined frequency band basis.