JP2001203656A - Base station device and propagation path estimate method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a propagation path estimate method that can effectively estimate an outgoing line in a wireless communication system where the frequency band for an incoming line and the frequency band for the outgoing line are asymmetrical. SOLUTION: A communication terminal transmits a pilot symbol to a base station by using a part of a frequency band (f2) for the outgoing line and the base station estimates a propagation path for the received pilot symbol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base station apparatus and a propagation path estimating method used in an asymmetric communication wireless communication system in which a downlink frequency band is wider than an uplink.

[0002]

2. Description of the Related Art In recent years, in a wireless communication system in which demand is rapidly increasing, an uplink for transmitting a signal from a base station to a communication terminal and a downlink for transmitting a signal from the communication terminal to the base station are divided. The propagation path is estimated, and transmission power and transmission speed are set based on the estimated propagation path to transmit data.

[0003] As a method of separating the uplink and the downlink of a wireless communication system, TDD (Time Division Duplex) is used.
System, FDD (Frequency Division Duplex) system, C
There are three types of DD (Code Division Duplex).

[0004] Among them, the FDD system is a system in which an uplink and a downlink are divided by frequency, and different frequencies are used for the uplink and the downlink.

Here, in the future, it is expected that data communication in which the amount of information on the downlink is much larger than that on the uplink will be the mainstream, and wireless communication of asymmetric communication in which the frequency band of the downlink is wider than that of the uplink. System development is underway.

A wireless communication system in which the frequency bandwidths of the uplink and downlink are asymmetric is disclosed in Japanese Patent Application Laid-Open No. 8-274701.
And Japanese Patent Application Laid-Open No. 9-51304.

[0007]

However, up to now, in a wireless communication system in which the frequency bandwidths of the uplink and downlink are asymmetric, a method for the base station apparatus to effectively estimate the propagation path of the downlink is described. Is not disclosed. This is because propagation path characteristics such as Rayleigh fading characteristics are different between the uplink and the downlink, and it is not possible to estimate the propagation path characteristics of the downlink from received signals of the uplink.

The present invention has been made in view of the above points, and in a wireless communication system in which the frequency bandwidths of the uplink and the downlink are asymmetric, the propagation path of the downlink can be effectively estimated. An object is to provide a base station apparatus and a propagation path estimation method.

[0009]

According to the present invention, there is provided a base station apparatus comprising:
A communication terminal apparatus and a base station apparatus for performing wireless communication with asymmetrical uplink and downlink frequency bandwidths, and estimates a propagation path based on pilot symbols transmitted in a part of a downlink frequency band. A configuration including a propagation path estimating means is adopted.

[0010] According to this configuration, when the frequency of the uplink and the frequency of the downlink are the same, it is possible to consider that the characteristics of the propagation paths near each other in time are almost equal. Based on this, the base station apparatus can perform propagation path estimation, and can effectively perform downlink propagation path estimation in a wireless communication system in which the uplink and downlink have asymmetric frequency bandwidths.

[0011] In the base station apparatus of the present invention, the frequency band in which pilot symbols are transmitted from the communication terminal apparatus is time-divided by the number of communication terminal apparatuses performing wireless communication or more, and is assigned to each communication terminal apparatus. Take the configuration.

In the base station apparatus of the present invention, a frequency band in which pilot symbols are transmitted from a communication terminal apparatus is code-divided by the number of communication terminal apparatuses performing wireless communication or more, and assigned to each communication terminal apparatus. Take the configuration.

The base station apparatus of the present invention employs a configuration in which a frequency band for transmitting a pilot symbol is individually allocated to each communication terminal apparatus.

[0014] With these configurations, each communication terminal can transmit a pilot symbol using the assigned radio channel, so that the base station can estimate a propagation path for each communication terminal.

The base station apparatus of the present invention employs a configuration in which a plurality of frequency bands in which pilot symbols are transmitted from a communication terminal apparatus are assigned to each communication terminal.

In the base station apparatus according to the present invention, the propagation path estimating means estimates the propagation path in the frequency band in which the pilot symbol is transmitted from the communication terminal apparatus, and interpolates the estimated propagation path to transmit the pilot symbol. A configuration for estimating the propagation path of the frequency band not performed is adopted.

With these configurations, it is possible to perform propagation path estimation by interpolating a band in which pilot symbols are not transmitted, so that the quality of propagation path estimation can be improved.

The base station apparatus of the present invention employs a configuration including a signal transmitting means for transmitting a downlink signal by providing a guard band between a frequency band for transmitting a pilot symbol and a frequency band for transmitting a downlink signal.

With this configuration, it is possible to prevent interference with a downstream signal.

The base station apparatus according to the present invention employs a configuration in which a pilot symbol is allocated to at least an end of a downlink frequency band as a frequency band to be transmitted.

According to this configuration, there is no need to provide a guard band outside the frequency band of the downlink, so that the frequency utilization efficiency can be improved.

The base station apparatus of the present invention employs a configuration in which a downlink frequency band provided with a guard band is divided using a SAW filter.

With this configuration, the guard band can be narrowed, so that the efficiency of use of the frequency band can be increased.

The base station apparatus according to the present invention employs a configuration including an inverse equalization processing means for multiplying the inverse characteristic of the propagation path estimated by the propagation path estimation means by a modulation signal of transmission data.

According to this configuration, in a wireless communication system in which the frequency bandwidths of the uplink and downlink are asymmetric, the inverse equalization processing can be performed, so that the communication terminal device can be downsized.

The base station apparatus of the present invention transmits and receives signals from a plurality of antenna elements constituting an array antenna, and transmits and receives signals from each of the antenna elements based on the propagation path estimated by the propagation path estimation means. And a weighting means for weighting the signal.

With this configuration, in a wireless communication system in which the frequency bandwidths of the uplink and downlink are asymmetric, transmission and reception can be performed using the array antenna, so that the channel capacity can be increased.

[0028] A communication terminal apparatus according to the present invention transmits a pilot symbol in a part of a downlink frequency band to any one of the base station apparatuses.

According to this configuration, since each communication terminal can transmit a pilot symbol using the assigned radio channel, the base station can estimate a propagation path for each communication terminal.

The communication terminal apparatus of the present invention employs a configuration in which a downlink frequency band provided with a guard band is divided using a SAW filter.

With this configuration, the guard band can be narrowed, so that the efficiency of use of the frequency band can be increased.

The propagation path estimating method of the present invention provides a method for performing wireless communication in which the frequency bandwidths of the uplink and downlink are asymmetric.
A method is employed in which a communication terminal apparatus transmits pilot symbols to a base station apparatus in a part of a downlink frequency band, and estimates a propagation path based on the pilot symbols received by the base station apparatus.

According to this method, when the frequency of the uplink and the frequency of the downlink are the same, it is possible to consider that the characteristics of the propagation paths near each other in time are almost equal, so that the pilot symbol transmitted from the communication terminal apparatus is Based on this, the base station apparatus can perform propagation path estimation, and can effectively perform downlink propagation path estimation in a wireless communication system in which the uplink and downlink have asymmetric frequency bandwidths.

According to the propagation path estimation method of the present invention, the base station apparatus time-divides the frequency band in which the pilot symbols are transmitted from the communication terminal apparatus by the number of communication terminal apparatuses performing wireless communication or more. A method of allocating to each communication terminal apparatus and transmitting a pilot symbol at the time allocated to each communication terminal apparatus is adopted.

According to the propagation path estimation method of the present invention, the base station apparatus code-divides the frequency at which the pilot symbol is transmitted from the communication terminal apparatus by the number of communication terminal apparatuses performing wireless communication or more. A method of allocating to a communication terminal device and multiplying a pilot symbol by the code assigned to each of the communication terminal devices and transmitting the symbol is adopted.

According to the propagation path estimation method of the present invention, the base station apparatus separately allocates a frequency band for transmitting a pilot symbol to each communication terminal apparatus, and sets a pilot symbol in the frequency band to which each communication terminal apparatus is allocated. Take the method of sending.

According to these methods, each communication terminal can transmit a pilot symbol using the assigned radio channel, so that the base station can estimate a propagation path for each communication terminal.

According to the propagation path estimation method of the present invention, a plurality of frequency bands for transmitting pilot symbols are assigned to each communication terminal.

According to the propagation path estimation method of the present invention, a base station apparatus estimates a propagation path in a frequency band in which a pilot symbol is transmitted from a communication terminal apparatus, and interpolates the estimated propagation path to transmit a pilot symbol. A method of estimating the propagation path of the frequency band not performed is adopted.

According to these methods, propagation path estimation can be performed by interpolating a band in which pilot symbols are not transmitted, so that the quality of propagation path estimation can be improved.

The propagation path estimation method of the present invention employs a method of providing a guard band between a frequency band for transmitting pilot symbols and a frequency for transmitting downlink signals.

With this method, it is possible to prevent interference with downstream signals.

The propagation path estimating method of the present invention employs a method of assigning at least the end of the downlink frequency band as a frequency band for transmitting pilot symbols.

According to this method, it is not necessary to provide a guard band outside the frequency band of the downlink, so that the frequency use efficiency can be improved.

The propagation path estimation method of the present invention employs a method in which at least one of the base station device and the communication terminal device divides the frequency band of the downlink using a SAW filter.

According to this method, the guard band can be narrowed, so that the use efficiency of the frequency band can be improved.

The inverse equalization processing method of the present invention employs a method in which the base station apparatus multiplies the inverse characteristic of the propagation path estimated by any one of the above-described propagation path estimation methods with a modulated signal of transmission data.

According to this method, it is possible to perform inverse equalization processing in a wireless communication system in which the frequency bandwidths of the uplink and downlink are asymmetric, so that the size of the communication terminal device can be reduced.

According to the weighting method of the present invention, the base station
A method is employed in which signals are transmitted and received from a plurality of antenna elements constituting an array antenna, and a transmission signal is weighted based on a propagation path estimated by any of the above-described propagation path estimation methods.

According to this method, transmission and reception can be performed using an array antenna in a wireless communication system in which the frequency bandwidths of the uplink and downlink are asymmetric, so that the channel capacity can be increased.

[0051]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The gist of the present invention is that a downlink frequency band is frequency-divided, and a communication terminal transmits a pilot symbol using a part of a downlink frequency band known between apparatuses. , The base station receives this pilot symbol and estimates the propagation path based on the received power.

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

FIG. 1 is a block diagram showing a configuration of a base station according to one embodiment of the present invention.

In the base station shown in FIG.
1 receives a signal transmitted from a communication terminal in a frequency band (f1) unique to the uplink. The reception RF unit 102
Amplification processing, frequency conversion processing, and the like are performed on the signal received by the antenna 101 to extract a baseband signal. Demodulation section 103 performs demodulation processing on the baseband signal output from reception RF section 102 to extract received data.

The antenna 151 receives a signal transmitted from the communication terminal at a frequency (fp1, fp2... Fpn) known between the apparatuses in the frequency band (f2) unique to the downlink. Also, the frequency band specific to the downlink (f2)
Among them, the transmission signal whose frequency has been converted to the frequency band (fd1, fd2... Fdn) is transmitted.

Duplexer 152 outputs the reception signal received by antenna 151 to reception RF section 153, and outputs the transmission signal output from transmission RF section 157 to antenna 151.

Reception RF section 153 performs amplification processing, frequency conversion processing, and the like on the signal received by antenna 151 to extract pilot symbols. Propagation path estimation unit 154
Performs an equalization process on pilot symbols output from the reception RF section 153 to estimate a propagation path.

Further, modulation section 155 performs modulation processing such as QPSK on transmission data. The precoder 156
A process (precoding) of multiplying the output signal of the modulation unit 155 by the inverse characteristic of the propagation path characteristic estimated by the propagation path estimation unit 154 is performed. The transmission RF unit 157 performs amplification processing, frequency conversion processing, and the like on the transmission signal output from the precoder 156, and transmits the transmission signal from the antenna 151.

FIG. 2 is a block diagram showing a configuration of the communication terminal according to the present embodiment.

In the communication terminal shown in FIG.
1 performs modulation processing such as QPSK on transmission data. The transmission RF section 202 performs amplification processing, frequency conversion processing, and the like on the output signal of the modulation section 201, and outputs a signal in the frequency band (f1). The antenna 203 has a transmission R
The output signal of F section 202 is transmitted to the base station in frequency band (f1).

The antenna 251 receives a signal transmitted from the base station device at a frequency (fd1, fd2... Fdn) known between the devices in the frequency band (f2) unique to the downlink. Also, the frequency band (fp1, fp2... Fpn)
Is transmitted.

[0062] Duplexer 252 outputs the reception signal received by antenna 251 to reception RF section 253, and outputs the transmission signal output from transmission RF section 256 to antenna 251.

The reception RF section 253 performs amplification processing, frequency conversion processing, and the like on the signal received by the antenna 251 to extract the received signal. The demodulation unit 254 includes the reception RF unit 2
A demodulation process is performed on the reception signal output from 53 to extract reception data.

Further, pilot symbol generating section 255
Generates pilot symbols used for estimating the propagation path at the base station. Transmission RF unit 256
Performs amplification processing, frequency conversion processing, and the like on pilot symbols output from pilot symbol generation section 255, and outputs a signal in the frequency band (f2). The antenna 256 transmits a signal whose frequency has been converted to the frequency band (f2).

Next, the flow of an uplink signal in the frequency band (f1) according to the present embodiment will be described.

Data transmitted from the communication terminal is modulated by modulation section 201 and amplified by transmission RF section 202.
The frequency is converted to the frequency band (f1), and the antenna 201
Is transmitted wirelessly to the base station.

Then, the signal in the frequency band (f 1) wirelessly transmitted from the communication terminal is received by the antenna 101 of the base station, amplified by the reception RF section 102, frequency-converted to baseband, and transmitted to the demodulation section 103. Demodulated to extract data.

Next, the flow of downlink signals in the frequency band (f2) according to the present embodiment will be described.

The data transmitted from the base station is transmitted to modulation section 1
55, pre-coded by a precoder 156, spread by a spreading unit 157, and transmitted by a transmission RF unit 158.
, And is frequency-converted to a part of the frequency band (f2) (fd1, fd2... Fdn), and is wirelessly transmitted from the antenna 151 to the communication terminal via the duplexer 152.

The signal in the frequency band (fd1, fd2... Fdn) wirelessly transmitted from the base station is received by the antenna 251 of the communication terminal, input to the reception RF section 253 via the duplexer 252, and received by the reception RF section. The signal is amplified at 253, frequency-converted to baseband, demodulated at demodulation section 254, and data is taken out.

Next, the flow of an uplink signal in the frequency band (f2) in the present embodiment will be described.

Pilot symbol generation section 25 of communication terminal
The pilot symbol generated in the transmission RF unit 25
The frequency band is amplified at 6, and the frequency is converted to a part of the frequency band (f2) (fp1, fp2... Fpn), and is transmitted by radio from the antenna 251 to the base station via the duplexer 252.

The signal in the frequency band (fp1, fp2... Fpn) wirelessly transmitted from the communication terminal is received by the antenna 151 of the base station, input to the reception RF section 153 via the duplexer 152, and received by the reception RF section. Amplified at 153, frequency-converted to baseband, and propagation path estimation unit 15
4 is input. The propagation path estimation unit 154 performs an equalization process using pilot symbols, and estimates a propagation path.

Next, the types of signals in each frequency band (f1, f2) will be described with reference to FIG.

In FIG. 3, frequency fd is a frequency for a downlink signal transmitted from the base station, and frequency fp is
This is a frequency for a signal obtained by modulating a pilot symbol transmitted from a communication terminal.

As shown in FIG. 3, in the frequency band (f1), uplink data is constantly transmitted from the communication terminal to the base station. On the other hand, in the frequency band (f2), the downlink data transmitted from the base station to the communication terminal includes the frequency bands (fd1, fd2,...).
fdn), and a pilot symbol transmitted from the communication terminal to the base station has a frequency band (f2)
Are transmitted in a part of the frequency band (fp1, fp2... Fpn).

As described above, when the frequency of the uplink and the frequency of the downlink are the same, it is possible to consider that the characteristics of the propagation paths in the vicinity in time are almost equal, and
By the FDD scheme of transmitting pilot symbols at a frequency known between apparatuses, the base station can estimate a propagation path based on the immediately preceding pilot symbol, and compensate for the influence of the propagation path of the transmission signal by precoding. Can be.

Here, the base station allocates radio channels to a plurality of communication terminals and performs radio communication simultaneously. This is the same for the pilot symbol in the present invention.

As a system for dividing a plurality of radio channels, a TDMA (Time Division Multiple Access) system, an FDMA (Frequency Division Multiple Access) system
And CDMA (Code Division Multiple Access).

Hereinafter, a case where a radio channel for transmitting pilot symbols is divided by the FDMA method among these methods will be described with reference to FIG.

In the case of the FDMA system, as shown in FIG. 4, a part of the frequency band (f21, f2) of the frequency band (f2) is used.
.. F2n) are assigned to the communication terminals (u1, u2... Un), and each communication terminal transmits a pilot symbol at the assigned frequency. Then, the base station receives the pilot symbols at the assigned frequencies and estimates the propagation path at each frequency. Thereby, the base station can estimate a propagation path for each communication terminal.

In addition, the radio channel can be divided by the TDMA system or the CDMA system. Also in these systems, each communication terminal transmits a pilot symbol using the allocated radio channel, thereby allowing the base station to transmit. Can estimate the propagation path for each communication terminal.

As shown in FIG. 5, by providing guard bands on both sides of a frequency band for transmitting pilot symbols, it is possible to prevent interference with a downlink signal. In this case, if a pilot symbol is transmitted at the end of the frequency band (f2), it is not necessary to provide a guard band outside the frequency band (f2), so that the frequency utilization efficiency can be improved.

In the base station and each communication terminal, S
If the AW filter is used to divide the downlink frequency band provided with the guard band, the guard band can be narrowed, and the frequency band utilization efficiency can be increased.

As shown in FIG. 6, in the FDMA system, pilot symbols of each communication terminal (u1, u2... Un) can be transmitted using two or more locations in the frequency band (f2). By this means, it is possible to perform propagation path estimation by interpolating a band in which pilot symbols are not transmitted, thereby improving the quality of propagation path estimation.

The present invention is also effective for a base station transmitting a signal using an array antenna, as shown in FIG.
The base station of FIG. 7 is different from the base station of FIG.
Reference numeral 51 denotes an array antenna including the antenna elements 151-1 to 151-n, which has a configuration in which weighting units 161-1 to 161-n and an adding unit 162 are added.

The weighting sections 161-1 to 161-n control each antenna element 151 based on the control of the propagation path estimation section 154.
Weighting is performed on signals transmitted and received from -1 to 151-n.

The adding section 162 includes the weighting sections 161-1 to 161-1.
The weighted received signals output from 161-n are added.

The reception RF section 153 amplifies the signals received by the antenna elements 151-1 to 151-n of the antenna 151 and the addition result of the addition section 162,
A pilot symbol is extracted by performing frequency conversion processing and the like.

Propagation path estimating section 154 receives RF section 153
And performs an equalization process based on the pilot symbols output from to estimate the propagation path. Further, the propagation path estimation unit 154
Are weighting units 161-1 to 161-1 based on the estimated propagation path.
61-n.

[0091]

As described above, according to the base station apparatus and the propagation path estimation method of the present invention, a communication terminal transmits a pilot symbol in a frequency band known between apparatuses,
Since the base station can estimate the propagation path based on the immediately preceding pilot symbol, it effectively estimates the propagation path of the downlink in a wireless communication system in which the frequency bandwidth between the uplink and the downlink is asymmetric. can do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a base station according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a communication terminal according to the embodiment.

FIG. 3 is a diagram illustrating a relationship between a type of a signal and time in each frequency band according to the embodiment.

FIG. 4 is a first diagram illustrating a case where a radio channel for transmitting pilot symbols according to the above embodiment is divided by an FDMA scheme.

FIG. 5 is a second diagram illustrating a case where the radio channel for transmitting pilot symbols is divided by the FDMA scheme according to the above embodiment.

FIG. 6 is a third diagram illustrating a case where the radio channel for transmitting pilot symbols is divided by the FDMA scheme according to the above embodiment.

FIG. 7 is a block diagram showing a configuration of a base station having an array antenna according to one embodiment of the present invention.

[Explanation of symbols]

 101, 151, 203, 251 Antenna 102, 153, 253 Receiving RF unit 103, 254 Demodulation unit 152, 252 Duplexer 154 Propagation path estimation unit 155, 201 Modulation unit 156 Precoder 157, 202, 256 Transmission RF unit 161 Weighting unit 162 Addition Unit 255 pilot symbol generation unit

Claims (24)

[Claims] 1. A communication terminal apparatus, comprising: a base station apparatus for performing wireless communication in which a frequency bandwidth of an uplink and a downlink is asymmetrical, based on a pilot symbol transmitted in a part of a frequency band for a downlink. A propagation path estimating means for estimating a propagation path by using a base station apparatus. 2. The communication terminal device according to claim 1, wherein a frequency band in which pilot symbols are transmitted from the communication terminal device is time-divided by the number of communication terminal devices performing wireless communication or more, and assigned to each communication terminal device. Item 2. The base station device according to item 1. 3. A frequency band in which a pilot symbol is transmitted from a communication terminal device is code-divided by the number of communication terminal devices performing wireless communication or more, and assigned to each communication terminal device. Item 2. The base station device according to item 1. 4. The base station apparatus according to claim 1, wherein a frequency band for transmitting a pilot symbol is separately allocated to each communication terminal apparatus. 5. The base station apparatus according to claim 1, wherein a plurality of frequency bands in which pilot symbols are transmitted from the communication terminal apparatus are assigned to each communication terminal. 6. A propagation path estimating means for estimating a propagation path of a frequency band in which pilot symbols are transmitted from a communication terminal apparatus, and interpolating the estimated propagation path to a frequency band in which pilot symbols are not transmitted. The base station apparatus according to claim 1, wherein a propagation path is estimated. 7. A signal transmission means for transmitting a downlink signal by providing a guard band between a frequency band for transmitting a pilot symbol and a frequency band for transmitting a downlink signal. Item 7. The base station device according to any one of Items 6. 8. The base station apparatus according to claim 7, wherein a pilot symbol transmission frequency band is assigned to at least an end of a downlink frequency band. 9. The base station apparatus according to claim 7, wherein a downlink frequency band provided with a guard band is divided using a SAW filter. 10. The apparatus according to claim 1, further comprising an inverse equalization processing means for multiplying the inverse characteristic of the propagation path estimated by the propagation path estimation means by a modulation signal of transmission data. 2. The base station device according to 1. 11. Transmitting / receiving means for transmitting / receiving signals from a plurality of antenna elements constituting an array antenna, and weighting signals transmitted / received from each antenna element based on a propagation path estimated by a propagation path estimating means. The base station apparatus according to any one of claims 1 to 10, further comprising a weighting unit for performing the operation. 12. A communication terminal apparatus for transmitting a pilot symbol to a part of a downlink frequency band to the base station apparatus according to any one of claims 1 to 11. 13. The communication terminal apparatus according to claim 12, wherein a downlink frequency band provided with a guard band is divided using a SAW filter. 14. When performing wireless communication in which the uplink and downlink frequency bandwidths are asymmetric, a communication terminal apparatus transmits a pilot symbol to a base station apparatus in a part of a downlink frequency band, and A propagation path estimation method, wherein a propagation path is estimated based on the pilot symbols received by a station device. 15. The base station apparatus divides a frequency band in which a pilot symbol is transmitted from a communication terminal apparatus into time divisions by the number of communication terminal apparatuses performing wireless communication or more, and allocates the frequency band to each communication terminal apparatus; 15. The propagation path estimation method according to claim 14, wherein each communication terminal device transmits a pilot symbol at an allocated time. 16. A base station apparatus, wherein a frequency at which a pilot symbol is transmitted from a communication terminal apparatus is code-divided by the number of communication terminal apparatuses performing wireless communication or more and assigned to each communication terminal apparatus, The propagation path estimation method according to claim 14, wherein each communication terminal device multiplies the assigned symbol by a pilot symbol and transmits the result. 17. The base station apparatus separately allocates a frequency band for transmitting a pilot symbol to each communication terminal apparatus, and each of the communication terminal apparatuses transmits a pilot symbol in the allocated frequency band. The propagation path estimation method according to claim 14, wherein 18. The propagation path estimation method according to claim 14, wherein a plurality of frequency bands for transmitting pilot symbols are assigned to each communication terminal. 19. A base station apparatus estimates a propagation path of a frequency band in which a pilot symbol is transmitted from a communication terminal apparatus, and interpolates the estimated propagation path to propagate a propagation path of a frequency band in which a pilot symbol is not transmitted. 19. The propagation path estimation method according to claim 18, wherein the path is estimated. 20. The propagation path estimation method according to claim 14, wherein a guard band is provided between a frequency band for transmitting a pilot symbol and a frequency for transmitting a downlink signal. 21. The propagation path estimation method according to claim 20, wherein a pilot symbol transmission frequency band is assigned at least to an end of a downlink frequency band. 22. The propagation path estimation method according to claim 21, wherein at least one of the base station apparatus and the communication terminal apparatus divides a downlink frequency band using a SAW filter. 23. A base station apparatus multiplies a modulated signal of transmission data by an inverse characteristic of a propagation path estimated by the propagation path estimation method according to any one of claims 14 to 22. Inverse processing method. 24. The base station apparatus transmits and receives signals from a plurality of antenna elements forming an array antenna.
A weighting method for weighting a transmission signal based on a propagation path estimated by the propagation path estimation method according to any one of Claims 4 to 22.