JP2002141888A - Asymmetrical radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relax the performance required in the power amplifier of a mobile station side terminal in asymmetrical radio communication. SOLUTION: At the side of a mobile station 10, the symbol speed of an upstream link signal is made slower than that of the downstream link one, direct spread is performed by a spread code from a code generating part 17, an occupancy frequency band being the same as that of the downstream link is secured and the upstream link signal is transmitted from a transmitting part 14. Since signal power required in the upstream link becomes one over a scattering rate, the performance required for the power amplifier at the side of a mobile station 10 is relaxed. At the side of a base station 1, received radio wave is guided to the side of a receiving part 3 by a duplexer 18 and inversely spread so as to demodulate a signal. An inverse spread is performed by multiplying a reception signal by a code from a code generating part 6 generated by synchronization with a synchronizing signal from a code synchronizing and tracking part 4 through the use of a multiplier 5. The inversely spread signal is demodulated by a data demodulating part 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an asymmetric wireless communication method in which the transmission speed of a downlink is higher than that of an uplink, and in particular, an asymmetric radio communication for performing high-speed wireless transmission using a frequency band such as a millimeter wave band. About the method.

[0002]

2. Description of the Related Art Conventionally, the following systems have been considered for asymmetric wireless communication. First, as shown in FIG. 21, the FD is assumed to have different frequency bands for uplink and downlink.
D (frequency domain facing) method, a method of widening the link with the higher transmission speed (downlink in FIG. 21), as shown in FIG. 22, the same frequency band is used for uplink and downlink. (Time domain opposition) system to increase the occupation time of the link with the higher transmission speed (downlink in FIG. 22), or to either FDD or TDD as shown in the phase space diagram of FIG. Also, there is known a method in which a modulation method of a link having a higher transmission speed (downlink in FIG. 23) is converted into a multi-valued signal than a modulation method of a link having a lower transmission speed, and the like.

Here, if the frequency characteristics of the radio wave propagation path are known in advance, pre-equalization is performed on the base station side in order to reduce the load on the terminal of the mobile station, and the deterioration due to a delay wave or the like is compensated. Other methods are also known. As a method for estimating the frequency characteristic of the radio wave propagation path, a TDD communication method using the same frequency band is advantageous. This is because the uplink and downlink signals have the same frequency band, so that it is possible to estimate the frequency characteristic of the radio wave propagation path from one of the link signals. However, when the mobile station is moving at a high speed, it is difficult to achieve perfect pre-equalization because the frequency characteristic of the propagation path changes every moment. Is being done.

[0004] Even when the above-mentioned pre-equalization is performed in asymmetric wireless communication, it is desirable that the uplink and the downlink have the same frequency band and the same frequency bandwidth. With this configuration, pre-equalization is performed on the downlink signal by estimating the frequency characteristic of the radio wave propagation path from the uplink signal and passing through a filter having the inverse characteristic of the estimated frequency characteristic. be able to. Therefore, the scheme shown in FIG. 22, that is, the duplex scheme may be a scheme in which the occupation time of the link with the higher transmission speed is extended as TDD.

[0005] Conventional techniques relating to these pre-equalization and propagation path estimation are disclosed in JP-A-09-112179, JP-A-10-126331, and JP-A-2000-138.
656 and the like.

[0006]

However, in these conventional methods, since the modulation schemes on the base station side and the mobile station side are the same, both the uplink and downlink have the same frequency spectrum, and the There is a technical problem that the performance required for the power amplifier and the like of the station side terminal is severe.

An object of the present invention is to solve the above problems and to alleviate the performance required for a power amplifier or the like of a mobile station side terminal.

[0008]

In order to solve this problem, the present invention sets the symbol rate of an uplink signal, which is a transmission rate lower than that of the downlink, to be lower than that of the downlink, and directly spreads the symbol rate by a spreading code. This secures an occupied frequency band equivalent to that of the downlink. In addition, the base station estimates the frequency characteristic of the radio wave propagation path from the spread uplink signal, and performs pre-equalization by transmitting the downlink signal through a filter having the inverse characteristic of the estimated frequency characteristic. And reduce the load on the mobile station side terminal. Here, since the signal power required for the uplink is only required to be 1 / spreading rate as compared with the case where the signal is not spread, it is possible to relax the performance required for the power amplifier on the terminal side, and to reduce the power required for the terminal side. Since it is not necessary to provide a propagation path compensation circuit such as a transformer, the size of the terminal can be reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of an asymmetric wireless communication apparatus according to a first embodiment of the present invention. In FIG. 1, in an asymmetric wireless communication apparatus according to the present invention, a base station 1 has an antenna 2, a receiving unit 3, a code synchronization
The mobile station 10 includes a tracking unit 4, a multiplication unit 5, a code generation unit 6, a data demodulation unit 7, a transmission unit 8, a modulation unit 9, and a base station duplexer 18.
1, a reception unit 12, a data demodulation unit 13, a transmission unit 14, a data modulation unit 15, a multiplication unit 16, a code generation unit 17, and a mobile station duplexer 19.

In the first embodiment, in order to directly spread an uplink signal from mobile station 10 to base station 1, mobile station 1
At 0, the input signal is modulated by the data modulator 15, then spread by the spreading code from the code generator 17 in the multiplier 16, up-converted to a radio frequency by the transmitter 14, and radiated into the air from the antenna 11. . Here, in the data modulating unit 15, linear modulation (BPSK, QPSK, QAM) or non-linear modulation (FSK, MSK) is performed similarly to general CDM. In addition, the transmission signal power in the transmission unit 14 is sufficient to be 1 / spreading factor as compared with the power required to transmit a wideband signal having the same bandwidth as the downlink. That is, the performance required for the power amplifier of the mobile station 10 can be eased as compared with the case where the uplink and downlink modulation schemes are the same as in the related art.

As shown in FIG. 1, the receiving section 12 in the mobile station 10 has the same configuration as that for demodulating a signal that is not directly spread. Here, the center frequency of the transmission signal and the center frequency of the reception signal do not necessarily have to match, but considering that pre-equalization is performed on the base station 1 side as described later, the center frequency of transmission / reception is one. It is better to do it. Therefore, transmission and reception are temporally switched by the mobile station duplexer 19 as shown in FIG.

When the base station 1 receives an uplink signal from the mobile station 10, the base station duplexer 18 guides the radio wave received by the antenna 2 to the receiving section 3 and despreads the signal to demodulate the signal. Despreading can be realized by the multiplier 5 multiplying the received signal by the code generator 6 generated in synchronization with the synchronization signal from the code synchronization / tracking unit 4. The despread signal is demodulated by the data demodulation unit 7 as usual, and the signal is output. On the other hand, the downlink signal is modulated by the data modulation unit 9, then up-converted to the radio frequency by the transmission unit 8, and the base station duplexer 18 is switched to the transmission side to transmit the downlink signal.
Radiated from the air.

When the duplex system is the TDD system, it is necessary to switch between a duplexer for a base station and a duplexer for a mobile station by a transmission / reception switching control unit (not shown) to switch between transmission and reception.

(Embodiment 2) FIG. 2 is a block diagram showing a configuration of an asymmetric wireless communication apparatus according to a second embodiment of the present invention. The asymmetric wireless communication apparatus of the present invention in FIG. 2 has a configuration in which a base station transmission / reception switching control section 20 and a mobile station transmission / reception switching control section 21 are added to the asymmetric wireless apparatus shown in FIG. .

In the second embodiment, since the duplex system is the TDD system, both the mobile station 10 and the base station 1 need to switch transmission and reception temporally. Here, the uplink and downlink signals have a signal format including timing control information.

The base station transmission / reception switching control unit 20 switches the base station duplexer 18 in accordance with a received uplink signal or a transmission time and a reception time determined by a signal from an upper network. On the other hand, the mobile station 10 switches the duplexer 19 for the mobile station according to the transmission time and the reception time defined by the control information included in the downlink signal from the base station.

Although not shown, the data modulation section 9 and the data demodulation section 7 of the base station 1 are also operated based on the control signal from the base station transmission / reception switching control section 20, and the data of the mobile station 10 It is preferable that the modulation unit 15 and the data demodulation unit 13 also operate based on the control signal from the mobile station transmission / reception switching control unit 21 because the transmission and reception timing can be easily adjusted.

(Embodiment 3) FIG. 3 is a block diagram showing a configuration of an asymmetric wireless communication apparatus according to a third embodiment of the present invention. 3, the asymmetric wireless communication device of the present invention includes a transmission / reception time determination unit 22 in the base station 1 in addition to the asymmetric wireless device shown in FIG. The upper network 2 not shown in the first and second embodiments.
3 is also shown.

In the third embodiment, the transmission / reception time determination unit 22 requests the upper network to make the downlink time longer than the uplink time. Here, assuming that the bandwidth of the uplink signal is the same as the bandwidth of the downlink signal, the occupation time per symbol is equal to the spreading factor times that of the downlink signal because the uplink signal is spread. It is getting longer.

Therefore, if the time occupied by the downlink is to be made longer than the time occupied by the uplink signal, the number of symbols in the downlink signal should be equal to or more than twice the spreading factor. Can be.

(Embodiment 4) FIG. 4 is a block diagram showing a configuration of an asymmetric wireless communication apparatus according to a fourth embodiment of the present invention. 4, the asymmetric wireless communication apparatus according to the present invention includes a downlink signal capacity investigation unit 24 in a base station in addition to the asymmetric wireless apparatus shown in FIG.

In the fourth embodiment, the downlink signal capacity checking unit 24 obtains downlink signal request information included in the uplink signal from the mobile station 10, and downloads the signal capacity corresponding to the request information from the upper network. It checks before transmitting the link signal and notifies the transmission / reception time determination unit 22, and determines the time required for the downlink according to the magnitude of the signal capacity and makes a request to the upper network. If there is no particular problem on the network side in response to the request, the higher-level network inputs a downlink signal having a capacity corresponding to the occupation time according to the request to the data modulator.

As described above, if the occupation time of the downlink can be secured in advance based on the downlink signal request information from the uplink, the time spent until the information reaches the mobile station terminal can be saved. Therefore, the load on the terminal and the person using the terminal is small, which is preferable.

(Embodiment 5) FIG. 5 is a block diagram showing a configuration of an asymmetric wireless communication apparatus according to a fifth embodiment of the present invention. In FIG. 5, an asymmetric wireless communication apparatus according to the present invention includes, in addition to the asymmetric wireless apparatus shown in FIG.
Each mobile station 10 is provided with an FFT (fast Fourier transform) circuit system for OFDM modulation and demodulation. FFT of base station 1
The circuit system includes a serial / parallel converter 25, an IFFT (inverse Fourier transform) circuit 26, and a guard adding unit 27. The FFT circuit system of the mobile station 10 includes a guard removing unit 28,
It comprises an FFT circuit 29 and a parallel / serial converter 30.

In the fifth embodiment, in order to transmit OFDM as a downlink signal from base station 1, a signal mapped by data modulation section 9 of base station 1 is converted by serial / parallel converter 25 into a serial / parallel converter. The signal is input to the IFFT circuit 26, and is converted from a signal on the frequency axis to a signal on the time axis. In order to increase the resistance to delayed waves and reduce the accuracy required for symbol timing synchronization, the guard adding unit 27 The signal of the latter half of the symbol is copied at the beginning. The OFDM signal to which the guard has been added is up-converted to a radio frequency by the transmission unit 8 and radiated from the antenna 2 to the air in the same manner as in normal single carrier modulation.

The mobile station 10 removes a guard from a signal down-converted by the receiving unit 12 in the guard removing unit 28 and demodulates the signal on the frequency axis by the FFT circuit 29 in order to demodulate a downlink signal which is OFDM. Then, demodulation is performed after the signal is converted into a serial signal by the parallel / serial conversion unit 30. The guard removing unit 28 includes a function of detecting a symbol timing, and is configured to remove a guard section at an appropriate timing. Here, transmission and reception of the uplink signal have the same configuration as in the first embodiment and the like.

(Embodiment 6) FIG. 6 is a block diagram showing a configuration of an asymmetric wireless communication apparatus according to a sixth embodiment of the present invention. 6, the asymmetric wireless communication apparatus of the present invention includes a propagation path estimating unit 31 and an inverse characteristic filter 32 in the base station 1 in addition to the asymmetric wireless apparatus shown in FIG.

In the sixth embodiment, the propagation path estimating unit 31 estimates the frequency characteristic of the propagation path from the uplink signal, and the base station 1 preliminarily calculates an inverse characteristic filter that has an inverse characteristic to the estimated propagation path characteristic. 32 to compensate for the deterioration of signal quality due to a delayed wave or the like. The mobile station 10 does not need to provide a filter for compensating signal quality degradation even when the influence of the delay wave or the like is large, and the load on the terminal may be small.

If the estimated frequency characteristic of the propagation path is different between the upstream and downstream, this compensation is incomplete and the signal quality is degraded. Therefore, a device for accurately estimating the frequency characteristic is required. For example, a known symbol for frequency characteristic estimation is transmitted as an uplink signal, a correlation between the received known symbol and a known symbol prepared in advance on the base station side is calculated, and the magnitude and delay time of the delay wave are calculated. Ask. In the present invention, the uplink signal is a signal that is directly spread, and may be despread with a known spreading code.

Here, since the received signal also includes thermal noise, when estimating the characteristics of the delayed wave, a known symbol is transmitted over a plurality of symbols, and a plurality of correlation results are averaged to influence the thermal noise. Is desirable. However, the number of symbols needs to be large enough to follow the frequency characteristic fluctuation of the propagation path caused by the movement of the mobile station 10. In the inverse characteristic filter 32, it is necessary to set a tap coefficient that cancels out the estimated delay wave, and to be able to adaptively change the tap coefficient according to the characteristic change.

Here, it is preferable to use the output signal of the receiving section before despreading for estimating the frequency characteristic of the propagation path, because it is possible to estimate the frequency characteristic over a wide band. Further, even if the signal after despreading is used, it is possible to highly accurately estimate a narrow-band channel frequency characteristic. It is also preferable to perform estimation with high accuracy and wide band using both of them.

When calculating a correlation with a known symbol, it is necessary to establish symbol synchronization and code synchronization. Therefore, it is also preferable to use a synchronization signal from a code synchronization / tracking unit. It is also preferable to calculate the correlation using the code from the code generator.

(Embodiment 7) FIG. 7 is a block diagram showing a configuration of an asymmetric wireless communication apparatus according to a seventh embodiment of the present invention. 7, the asymmetric wireless communication apparatus according to the present invention includes a propagation path estimating unit 33 and a weighting unit 34 in the base station 1 in addition to the asymmetric wireless apparatus shown in FIG.

In the seventh embodiment, similarly to the sixth embodiment, the base station 1 compensates in advance for signal quality deterioration due to a delayed wave or the like. However, unlike the sixth embodiment, the propagation path estimator The means for realizing the inverse characteristic of the frequency characteristic of the propagation path estimated in 33 is not a filter, but an OFDM.
This is realized by weighting by the weighting unit 34 at the input part to the IFFT circuit 26 used for the system.

More specifically, first, the magnitude of the delay wave obtained by the same method as in the sixth embodiment and the frequency characteristics of the impulse serving as the delay time are obtained. A weighting unit 3 is provided at the input stage to the IFFT circuit 26 so as to have an inverse characteristic of the frequency characteristic.
4 are provided and each subcarrier is weighted. Here, the weighting section 34 changes the magnitude and phase of the input complex signal. If the step size of the estimated frequency characteristic is different from the step size of the IFFT circuit 26, it is necessary to appropriately perform interpolation or extrapolation. The method of estimating the frequency characteristic is the same as that of the sixth embodiment.

(Eighth Embodiment) FIG. 8 is a block diagram showing a configuration of an asymmetric wireless communication apparatus according to an eighth embodiment of the present invention. FIG. 8 shows only base station 1 in the eighth embodiment. The mobile station 10 is the same as in FIG. FIG.
3 shows a configuration corresponding to a case where the number of mobile stations 10 is three.

In FIG. 8, base station 1 includes a channel characteristic estimating unit (for #a) 35, an inverse characteristic filter (for #a) 36, a data modulating unit 37, a channel characteristic estimating unit (for #b) 38, Characteristic filter (for #b) 39, data modulator 40, channel characteristic estimator (for #c) 41, inverse characteristic filter (for #c)
42, a data modulation section 43, a data demodulation section 44, a despreading section (for #a) 45, a data demodulation section 46, a despreading section (#b
47), data demodulation unit 48, despreading unit (for #c) 4
9, a switch 101, a receiving unit 3, a transmitting unit 8, a duplexer 18, and an antenna 2.

Embodiment 8 shows a case in which asymmetric communication is performed with respect to a plurality of mobile stations 10, and propagation path characteristic estimating units 35, 38, 41, inverse characteristic filters 36, 39, 4
2. Each of the data modulators 37, 40, and 43 is required for the corresponding mobile station. FIG. 8 shows a case where the number of mobile stations 10 is three (#a, #b, #c), and the configuration is such that channel characteristics can be separately estimated for each mobile station 10.

Each mobile station 10 is synchronized with the base station 1 and transmits at the timing shown in FIG. The base station 1 receives an uplink signal and estimates propagation path characteristics from each mobile station 10. More specifically, each mobile station is multiplied by a different spreading code to determine the respective channel impulse characteristics. The inverse characteristic filters 36, 39, 42 are provided with tap coefficients for eliminating the delayed wave portion from the obtained impulse characteristics, and the data modulating units 37, 40,
The signal modulated at 43 is passed through the inverse characteristic filter 36,
Input to 39 and 42. Since the downlink signal is transmitted by TDM (time division multiplexing), the switch 101 switches and transmits the downlink signal for each mobile station.

In the demodulation of the uplink signal, the despreading units 45, 47 and 49 and the data demodulating unit 4 for the number of mobile stations are used.
4, 46 and 48 are required, and despreading units 45, 47 and 4
In the ninth embodiment, as shown in FIG. 6 of the sixth embodiment, a code is generated by a code generation unit 6 in synchronization with a synchronization signal from a code synchronization / tracking unit 4 and multiplied by a multiplier 5. . Here, since the mobile stations 10 are synchronized with each other, the code synchronization / tracking unit 4 does not need to be configured for each mobile station, and can be shared by the despreading units 45, 47, and 49.

(Embodiment 9) FIG. 10 is a block diagram showing a configuration of an asymmetric wireless communication apparatus according to a ninth embodiment of the present invention. FIG. 10 shows only base station 1 in the ninth embodiment. The mobile station 10 is the same as in FIG.
FIG. 10 particularly shows a configuration corresponding to a case where the number of mobile stations 10 is three.

In FIG. 10, the base station 1 includes a propagation path characteristic estimating unit (for #a) 50, a data modulating unit 51, and a serial / parallel converting unit 52, in addition to the uplink signal demodulating unit having the same configuration as that of FIG. , Weighting section (for #a) 53, IFFT
Unit 54, guard adding unit 55, channel characteristic estimating unit (#a
56, a data modulation unit 57, a serial / parallel conversion unit 58, a weighting unit (for #a) 59, an IFFT unit 60,
A guard adding unit 61, a channel characteristic estimating unit (for #a) 62,
It comprises a data modulation section 63, a serial / parallel conversion section 64, a weighting section (for #a) 65, an IFFT section 66, and a guard addition section 67.

In the ninth embodiment, the inverse characteristic filter units 36, 39 and 42 in the base station 1 shown in FIG. 8 have the weighting unit 5 provided at the input stage of the IFFT units 54, 60 and 66.
3, 59 and 65 are supported. The weighting unit 5
The configuration of 3, 59, 65 is the same as that of mobile station 1 shown in Embodiment 7.
0 is the same as in the case of one, and these weighting units 5
3, 59 and 65 are provided for the number of mobile stations. The operation of each unit is the same as in the seventh and eighth embodiments.

(Embodiment 10) FIGS. 11 and 12 are block diagrams showing a configuration of an asymmetric wireless communication apparatus according to a tenth embodiment of the present invention. 11 and 12
Shows only the base station 1. The mobile station 10 is the same as in FIG. FIGS. 11 and 12 show a configuration corresponding to a case where the number of mobile stations 10 is three.

FIG. 11 shows Embodiment 8 of Embodiment 10 of the present invention.
FIG. 12 shows a case where the tenth embodiment is applied to the ninth embodiment. The base station 1 shown in FIG. 11 has a C / N estimating unit 68 for estimating the C / N of the uplink signal from each mobile station 10 in addition to the configuration of FIG. In addition, the base station 1 shown in FIG. 12 also has a C / N for estimating the C / N of the uplink signal from each mobile station in addition to the configuration of FIG.
/ N estimation unit 69.

11 and 12, the C / N estimation unit 6
Reference numerals 8 and 69 provide the switch with parameters for determining the order in which the downlink signals to each mobile station 10 are transmitted. The mobile station 10 having a higher estimated C / N can be regarded as having a shorter distance from the base station 1, and it is highly likely that the mobile station 10 is moving near the base station 1 at a high speed (at a high angular velocity). Therefore, it is considered that the fluctuation of the radio wave propagation path is also large. Therefore, as the time elapses, there is a high possibility that the error from the estimated radio wave propagation path becomes larger. Therefore, a downlink signal is transmitted before the mobile station 10 having a low C / N.

Note that the order of transmission to each mobile station 10 is such that if a control channel indicating the order is added to the beginning of the frame, each mobile station 10 need only demodulate the symbols in its own order. Low power consumption can be achieved. In addition, information indicating which mobile station 10 the signal is for is added to the downlink signal for each mobile station 10, and each mobile station 10 demodulates only this information and is a transmission signal for its own station. It is also preferable to adopt a configuration in which all downlink signals are demodulated only in the case.

(Embodiment 11) FIGS. 13 and 14 are block diagrams showing a configuration of an asymmetric wireless communication apparatus according to an eleventh embodiment of the present invention. 13 and 14
Shows only the base station 1. The mobile station 10 is the same as in FIG. FIG. 13 and FIG. 14 show configurations particularly corresponding to the case where the number of mobile stations 10 is three.

FIG. 13 shows Embodiment 8 of Embodiment 11 of the present invention.
FIG. 14 shows a case where the eleventh embodiment is applied to the ninth embodiment. The radio communication apparatus shown in FIG. 13 includes a C / N estimation unit 70 and a gain adjustment unit 71 for estimating the C / N of an uplink signal from each mobile station in addition to the configuration in FIG. Further, the wireless communication apparatus shown in FIG. 14 includes a C / N estimation unit 72 and a gain adjustment unit 73 for estimating the C / N of an uplink signal from each mobile station in addition to the configuration in FIG.

13 and 14, the C / N estimating section 7
0 and 72 determine the size of the downlink signal to be transmitted. Since the mobile station 10 having a higher estimated C / N can be regarded as having a shorter distance from the base station 1, the gain adjusters 71 and 73 are controlled so as to transmit with lower power. Conversely, C
Since the mobile station 10 with a lower / N can be considered to be farther from the base station 1, the gain adjusters 71 and 73 are controlled to transmit with higher power.

(Twelfth Embodiment) FIGS. 15 and 16 are block diagrams showing a configuration of an asymmetric wireless communication apparatus according to a twelfth embodiment of the present invention. FIG. 15 shows the base station 1 in the asymmetric wireless communication apparatus of the present invention, and FIG. 16 shows the mobile station 10.

FIG. 15 shows a case where the number of mobile stations is three as in FIG. 8, and includes a circuit for multicarrier CDMA in addition to the configuration of FIG. The circuit for multi-carrier CDMA includes a guard remover 74, an FFT circuit 75, a parallel / serial converter 76, a multiplier 77, a code generator (for #a) 78, and a propagation path estimator (for #a) 7.
9, a multiplier 80, a code generator (for #b) 81, a propagation path estimator (for #b) 82, a multiplier 83, a code generator (#c)
) 84 and a channel estimation unit (for #c) 85.

The mobile station shown in FIG. 16 includes a multicarrier CDMA receiving circuit in a receiving section in addition to the configuration of the mobile station shown in FIG. This multi-carrier CDMA
The receiving circuit includes a multiplication unit 86, a code generation unit 87, a serial / parallel conversion unit 88, an IFFT circuit 89, and a guard addition unit 90.

In the twelfth embodiment, uplink signals from a plurality of mobile stations 10 are multiplexed by multicarrier CDMA. The mobile stations 10 are synchronized with each other so that the transmission timing is the same. The signal modulated by the data modulator 15 is multiplied by the code from the code generator 87 in the multiplier 86, and the signal is parallelized by the serial / parallel converter 88. After being converted into a signal, the signal is converted into a signal on the time axis by an IFFT circuit 89, and then a guard is added by a guard adding unit 90, up-converted to a radio frequency by a transmitting unit, and then radiated into the air.

In the base station 1, each mobile station 10
The symbol removal is performed on the uplink signal transmitted at the same timing from the above, and the guard signal portion is removed by the guard removal section 74. Next, after being converted into a signal on the frequency axis by the FFT circuit 75, different spreading codes are output from the code generators 78, 81 and 84 by the respective mobile stations 10, and multiplied by the multipliers 77, 80 and 83. After that, the propagation path estimating units 79, 82, 85
, And at the same time, demodulation is performed by the data demodulation units 44, 46, and 48. Each mobile station 1
The downlink signals for 0
After passing through the inverse characteristic filters 36, 39, and 42, which have characteristics opposite to the characteristics estimated after the modulation at 43, the signals are compensated for the signal degradation factor in the propagation path, and then input to the switch 101.
A time-division multiplexed signal is transmitted to each mobile station 10.

Here, FIG. 15 does not show the case where the downlink signal is OFDM, but it is applicable to the case where the downlink signal is OFDM by using the same configuration as FIG.

(Embodiment 13) FIG. 17 shows a first embodiment of the present invention.
FIG. 14 is a block diagram illustrating a configuration of an asymmetric wireless communication device according to a third embodiment. In FIG. 17, the asymmetric wireless communication apparatus of the present invention is the same as the asymmetric wireless communication apparatus of FIG.
, A transmitting antenna 92 is provided separately from the receiving antenna 2, and the mobile station 10 is also provided with a transmitting antenna 94 separately from the receiving antenna 11 by using a subtractor 93 instead of the duplexer 19. I have.

In the present embodiment, the uplink and downlink use the same frequency channel, and the transmission of the uplink and downlink signals is allowed at the same time. And a receiving antenna are separately provided. Here, the receiving antenna 2 and the transmitting antenna 92 and the receiving antenna 11 and the transmitting antenna 93
Is near, the transmission signal is large compared to the size of the reception signal, and reception may be difficult.
At 1 and 93, the transmission signal is subtracted from the output of the receiving antenna and then input to the receiving units 3 and 12.
With such a configuration, a transmission signal component known in advance can be removed, and reception interference can be reduced.

Here, when the phases of the downlink signal from the antenna and the transmission signal prepared for canceling the signal are not aligned in the subtraction sections 91 and 93 in the output of the receiving antenna, the receiving section is warped. The interference can be large. Therefore, as shown in FIG.
Preferably, each of the mobile stations 10 obtains an error after subtraction from the signal output from the receiving unit, and controls the phase and gain of the transmission signal to be subtracted so as to minimize the error. That is, an error detection section 95 is provided on the base station 1 side to obtain an error after subtraction from the signal output from the reception section, and the gain adjustment section 96 and the phase adjustment section 97 subtract the transmission signal to be subtracted so as to minimize this error. Control phase and gain. Similarly, an error detection unit 98, a gain adjustment unit 99, and a phase adjustment unit 100 are provided on the mobile station 10 side to perform the same processing.

(Embodiment 14) FIG. 19 shows a first embodiment of the present invention.
FIG. 16 is a block diagram illustrating a configuration of an asymmetric wireless communication device according to a fourth embodiment. FIG. 19 shows only a mobile station, and includes a power detection section 102 and a gain adjustment section 103 in addition to the configuration of the mobile station in the asymmetric wireless communication apparatus of FIG. 1 shown in Embodiment 1.

In the fourteenth embodiment, the received power of the received downlink signal is detected by power detection section 102, and when the received power is small, gain adjustment section 103 controls so that the transmission power of the uplink signal is increased. I do. When a plurality of mobile stations 10 exist, the uplink signal is subjected to CDM (code division multiplexing), so that the transmission power control is important in order not to break the orthogonality between the mobile stations 10.

According to this embodiment, simple transmission power control can be performed, and the size of the apparatus can be reduced.

(Embodiment 15) FIG. 20 shows a first embodiment of the present invention.
FIG. 16 is a block diagram illustrating a configuration of an asymmetric wireless communication device according to a fifth embodiment. In FIG. 20, the asymmetric wireless communication apparatus of the present invention has, in addition to the configuration of the asymmetric wireless communication apparatus of FIG.
However, the mobile station 10 includes a spreading factor / symbol length determining unit 105 and a symbol length adjusting unit 106.

In the fifteenth embodiment, the environment of the radio wave propagation path, the load on the network, and the QoS (communication service quality)
For the purpose of adaptively controlling the uplink and downlink transmission rates and transmission quality that fluctuate according to requests and the like, the spreading factor and the symbol length when directly spreading the uplink signal from the mobile station 10 are changed. In the mobile station 10, the spreading factor / symbol length is determined by the spreading factor / symbol length determining unit 105 based on the control signal, and adjusted to the symbol length determined by the symbol length adjusting unit 106. In addition, the spreading factor is changed by changing the spreading code to be directly spread.

In the base station 1, the spreading factor of the uplink signal is determined by the spreading factor determining unit 104 based on the signal from the upper layer network that is issuing the control signal in the mobile station 10, and the determined spreading factor is determined. The code synchronization / tracking unit 4 establishes chip synchronization and symbol synchronization so that the corresponding spread codes can be used for despreading. After synchronization is established, despreading is performed.

With the above-described configuration, when the occupied bandwidth is constant and the primary modulation scheme remains constant, and the time occupied by the uplink is to be shortened, the spreading factor is reduced and the symbol length is reduced. Just shorten it. If it is desired to reduce the power consumption of the power amplifier in the mobile station terminal by increasing the occupation time, the symbol length can be increased by increasing the spreading factor. Since the occupied bandwidth is constant as described above, the radio wave propagation path characteristics can be estimated even when the occupied time of the uplink is changed, which is particularly suitable for performing pre-equalization.

[0068]

As described above, according to the present invention, the uplink signal from the mobile station to the base station is directly spread and transmitted, and the base station despreads with the same code as the code spread by the mobile station. By doing so, it is possible to reduce the transmission power of the uplink signal having a small transmission capacity, and it is possible to relax the performance required for the power amplifier or the like of the mobile station side terminal.

Also, since the occupied frequency bandwidth of the uplink and the downlink can be kept constant, the frequency characteristic of the radio wave propagation path is estimated from the uplink signal spread on the base station side, and the downlink signal is estimated. It is possible to perform pre-equalization by transmitting the signal after passing through a filter having the inverse characteristic of the frequency characteristic, and it is not necessary to provide a propagation path compensation circuit such as an equalizer on the terminal side. I can do it.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a configuration of an asymmetric wireless communication device according to a first embodiment of the present invention.

FIG. 2 is a block circuit diagram showing a configuration of an asymmetric wireless communication device according to a second embodiment of the present invention.

FIG. 3 is a block circuit diagram showing a configuration of a base station in an asymmetric wireless communication device according to a third embodiment of the present invention.

FIG. 4 is a block circuit diagram showing a configuration of a base station in an asymmetric wireless communication device according to a fourth embodiment of the present invention.

FIG. 5 is a block circuit diagram showing a configuration of an asymmetric wireless communication device according to a fifth embodiment of the present invention.

FIG. 6 is a block circuit diagram showing a configuration of an asymmetric wireless communication device according to a sixth embodiment of the present invention.

FIG. 7 is a block circuit diagram showing a configuration of an asymmetric wireless communication device according to a seventh embodiment of the present invention.

FIG. 8 is a block circuit diagram showing a configuration of a base station in an asymmetric wireless communication apparatus according to an eighth embodiment of the present invention.

FIG. 9 is a diagram showing a time relationship between an uplink and a downlink according to an eighth embodiment of the present invention.

FIG. 10 is a block circuit diagram showing a configuration of a base station in an asymmetric wireless communication apparatus according to a ninth embodiment of the present invention.

FIG. 11 is a block circuit diagram showing a configuration of a base station in an asymmetric wireless communication apparatus according to a tenth embodiment of the present invention.

FIG. 12 is a block circuit diagram showing another configuration of the base station in the asymmetric wireless communication apparatus according to the tenth embodiment of the present invention.

FIG. 13 is a block circuit diagram showing a configuration of a base station in an asymmetric wireless communication apparatus according to an eleventh embodiment of the present invention.

FIG. 14 is a block circuit diagram showing another configuration of the base station in the asymmetric wireless communication apparatus according to the eleventh embodiment of the present invention.

FIG. 15 is a block circuit diagram showing a configuration of a base station in an asymmetric wireless communication apparatus according to a twelfth embodiment of the present invention.

FIG. 16 is a block circuit diagram showing a configuration of a mobile station in an asymmetric wireless communication apparatus according to a twelfth embodiment of the present invention.

FIG. 17 is a block circuit diagram showing a configuration of an asymmetric wireless communication device according to a thirteenth embodiment of the present invention.

FIG. 18 is a block circuit diagram showing another configuration of the asymmetric wireless communication device according to the thirteenth embodiment of the present invention.

FIG. 19 is a block circuit diagram showing a configuration of a mobile station in an asymmetric wireless communication device according to a fourteenth embodiment of the present invention.

FIG. 20 is a block circuit diagram showing a configuration of an asymmetric wireless communication device according to a fifteenth embodiment of the present invention.

FIG. 21 illustrates an example of a conventional asymmetric wireless communication apparatus, F.
Characteristic diagram explaining DD system

FIG. 22 shows T, which is an example of a conventional asymmetric wireless communication device.
Characteristic diagram explaining DD system

FIG. 23 is a phase space diagram for explaining a method of changing a modulation method, which is one mode of a conventional asymmetric wireless communication device,

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 base station 2 base station antenna 3 receiver 4 code synchronization / tracking unit 5 multiplier 6 code generator 7 data demodulator 8 transmitter 9 data modulator 10 mobile station 11 mobile station antenna 12 receiver 13 data demodulator REFERENCE SIGNS LIST 14 transmission unit 15 data modulation unit 16 multiplication unit 17 code generation unit 18, 19 duplexer 20 base station transmission / reception switching control unit 21 mobile station transmission / reception switching control unit 22 transmission / reception time determination unit 23 upper network 24 downlink signal capacity checking unit 25 Serial / parallel converter 26 IFFT circuit 27 guard adder 28 guard remover 29 FFT circuit 30 parallel / serial converter 31 channel estimator 32 inverse characteristic filter 33 channel estimator 34 weighter 35, 38, 41 channel estimator Units 36, 39, 42 Inverse characteristic filters 37, 40 , 43, 51, 57, 63 Data modulation sections 45, 47, 49 Despreading sections 44, 46, 48 50, 56, 62 Propagation path estimation sections 52, 58, 64 Serial / parallel conversion sections 53, 59, 65 Weighting sections 54, 60, 66 IFFT circuits 55, 61, 67 Guard adding section 68, 69, 70, 72 C / N estimating section 71, 73 Gain adjusting section 74 Guard removing section 75 FFT circuit 76 Parallel / serial converting section 77, 80, 83, 86 Multiplication units 78, 81, 84, 87 Code generation units 79, 82, 85, Channel estimation units 88 Serial / parallel conversion units 89 IFFT circuits 90 Guard addition units 91 Subtraction units 92 Downlink transmission antennas 93 Uplink Transmission antenna 94 Subtraction unit 95, 98 Error detection unit 96, 100 Phase adjustment unit 97, 99, 103 Gain Integer unit 98 error detection unit 101 switch 102 power detection unit 104 spreading factor determination unit 105 spreading factor / symbol length determination unit 106 symbol length adjusting unit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kentoku Kunieda 3-1-1, Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa F-term in Matsushita Giken Co., Ltd. 5K022 AA04 AA30 DD01 DD42 EE01 EE11 EE25 EE36 5K067 AA42 AA43 CC04 CC10 EE04 EE10 EE34

Claims (15)

[Claims] In an asymmetric wireless communication method in which the transmission rate of a downlink is higher than that of an uplink, an uplink signal from a mobile station is directly spread by a spreading code and occupies the same frequency bandwidth as the downlink. And transmitting a downlink signal from a base station without spreading. 2. The asymmetric wireless communication method according to claim 1, wherein the uplink and the downlink use the same frequency channel, and the duplex system is a TDD (time domain facing) system. 3. The asymmetric wireless communication method according to claim 2, wherein the time occupied by the downlink is longer than the time occupied by the uplink. 4. The occupancy time of the uplink and the downlink is variably changed according to the capacity.
The asymmetric wireless communication method according to the above. 5. The asymmetric wireless communication method according to claim 1, wherein the downlink modulation method is OFDM (Orthogonal Frequency Division Multiplexing). 6. The frequency characteristic of a radio wave propagation path is estimated from an uplink signal, and a downlink signal is transmitted through a filter having characteristics opposite to the frequency characteristic. Asymmetric wireless communication method according to any of the preceding claims. 7. The modulation method of a downlink signal is OFDM.
(Orthogonal frequency division multiplexing), and an input signal to an IDFT (inverse discrete Fourier transform) unit used in the modulation unit of the modulation scheme has an inverse characteristic to a frequency characteristic of a radio wave propagation path estimated from an uplink signal. 6. The asymmetric wireless communication method according to claim 5, wherein said method has a characteristic. 8. A plurality of mobile stations synchronize and directly spread with different spreading codes for transmission, and a base station performs despreading with the plurality of spreading codes and frequency characteristics of radio wave propagation paths for the respective mobile stations. 7. The downlink signal is transmitted after passing through a filter having characteristics opposite to those of the obtained frequency characteristics, and a duplex system is a TDD (time domain facing) system. Asymmetric wireless communication method. 9. A plurality of mobile stations synchronize and directly spread with different spreading codes for transmission, and a base station despreads with the plurality of spreading codes and frequency characteristics of a radio wave propagation path for each mobile station. And the modulation scheme of the downlink signal is set to OFDM, and the input signal to the IDFT (inverse discrete Fourier transform) unit used in the modulation unit of the modulation scheme includes:
The mobile station transmits a downlink signal to each mobile station with characteristics that are inverse characteristics of the respective frequency characteristics, and a duplex system is a TDD (time domain facing) system. Item 7. An asymmetric wireless communication method according to Item 7. 10. The mobile station according to claim 8, wherein a C / N is estimated based on an uplink signal from each mobile station, and a downlink signal for a mobile station having a high estimated C / N is transmitted first.
Or the asymmetric wireless communication method according to claim 9. 11. A C / N is estimated based on an uplink signal from each mobile station, and a C / N is estimated according to the estimated C / N.
The asymmetric wireless communication apparatus according to claim 8 or 9, wherein a downlink signal is transmitted with a larger power as / N is smaller. 12. An uplink signal from a mobile station is MC-
12. The asymmetric wireless communication method according to claim 8, wherein a CDMA (multi-carrier code division multiple access) system is used. 13. The asymmetric wireless communication method according to claim 1, wherein the uplink and the downlink use the same frequency channel, and the uplink signal and the downlink signal are allowed to be transmitted simultaneously. . 14. Transmission power control is performed such that the transmission power of an uplink signal is increased according to the reception power of a received downlink signal when the reception power is low and is decreased when the reception power is high. 2. The method according to claim 1, wherein
The asymmetric wireless communication method according to the above. 15. The asymmetric wireless communication method according to claim 1, wherein a symbol length and a spreading factor of an uplink signal are adaptively changed.