JP2001203611A - 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: Each communication terminal multiplies a spread code that is known among terminals and different from outgoing data with a pilot symbol with an outgoing line use frequency band (f2) and transmits the resulting symbol to a base station.

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, the transmission power and the transmission speed are set based on the estimation result, and the data is transmitted.

[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 uplink and downlink frequency bands are asymmetric has already been disclosed in Japanese Patent Application Laid-Open Nos. 8-274701 and 9-51304.

[0007]

However, up to now, in a wireless communication system in which the frequency bands of the uplink and the downlink are asymmetric, there is no method for the base station apparatus to effectively estimate the propagation path of the downlink. Not disclosed. This is because the propagation path characteristics such as Rayleigh fading characteristics are different between the uplink and the downlink, and it is difficult to estimate the propagation path of the downlink from the received signal of the uplink.

[0008] The present invention has been made in view of the above point, and in a radio communication system in which the frequency band between the uplink and the downlink is asymmetric, a base station capable of effectively estimating the propagation path of the downlink. It is an object to provide a station device and a propagation path estimation method.

[0009]

According to the present invention, there is provided a base station apparatus comprising:
A communication terminal device, a base station device performing wireless communication with asymmetrical uplink and downlink frequency bandwidths, wherein the base station device is multiplied by a spreading code from the communication terminal device in the same frequency band as the downlink and transmitted. And a propagation path estimating means for estimating a propagation path based on pilot symbols output from the despreading means.

[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 frequency band between the uplink and the downlink is asymmetric.

[0011] The base station apparatus of the present invention employs a configuration in which the frequency band of the downlink is time-divided by the number of communication terminal apparatuses performing wireless communication or more, and is assigned to each communication terminal apparatus.

The base station apparatus of the present invention employs a configuration in which the frequency band of the downlink is code-divided by the number of communication terminal apparatuses performing wireless communication or more, and assigned to each communication terminal apparatus.

[0013] The base station apparatus of the present invention employs a configuration in which a part of the downlink frequency band is assigned to each communication terminal apparatus that performs wireless communication.

The base station apparatus according to the present invention employs a configuration in which the frequency band of the downlink is frequency-divided by the number of communication terminal apparatuses performing wireless communication or more, and is assigned to each communication terminal apparatus.

[0015] 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 for transmitting pilot symbols 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 of 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, thereby improving the quality of propagation path estimation.

[0019] The base station apparatus of the present invention includes interference canceling means for canceling interference due to a signal other than a desired pilot symbol from a received signal, and propagation path estimating means for estimating a propagation path from the interference-eliminated signal. Take the configuration.

With this configuration, it is possible to eliminate interference caused by a signal transmitted by the base station itself and interference caused by a transmission signal other than that of the target communication terminal.

[0021] The base station apparatus of 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 estimating 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 size of the communication terminal device can be reduced.

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.

According to 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.

The communication terminal apparatus of the present invention employs a configuration in which a pilot symbol is multiplied by a spreading code in the same frequency band as the downlink and transmitted to any of the base station apparatuses.

With this configuration, 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.

[0027] The communication terminal apparatus of the present invention employs a configuration including an interference canceling unit for canceling interference due to a signal other than a desired signal from a received signal.

With this configuration, it is possible to eliminate interference caused by a signal transmitted by the communication terminal itself and interference caused by a transmission signal other than that of a target base station.

According to the propagation path estimation method of the present invention, when performing wireless communication in which the frequency bandwidth of the uplink and the downlink is asymmetric, the communication terminal apparatus transmits the base station apparatus to the same frequency band as the downlink. The base station apparatus despreads the received pilot symbols and estimates a propagation path based on the despread pilot symbols.

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 substantially 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 frequency band between the uplink and the downlink is asymmetric.

According to the propagation path estimating method of the present invention, the base station apparatus allocates time to the number of communication terminal apparatuses for wireless communication or more and allocates them to each communication terminal apparatus. A method is employed in which a pilot symbol is multiplied by a spreading code at a given time and transmitted.

According to the propagation path estimation method of the present invention, the base station apparatus code-divides by the number of communication terminal apparatuses performing wireless communication or more and allocates the divided code to each communication terminal apparatus. A method is adopted in which the obtained code is multiplied by a pilot symbol and transmitted.

According to the propagation path estimation method of the present invention, the base station device allocates a part of the downlink frequency band to each communication terminal device that performs radio communication, and A method of transmitting a signal in which a pilot symbol is multiplied by a spreading code using a part thereof is adopted.

According to the propagation path estimation method of the present invention, the base station apparatus divides the frequency by the number of communication terminal apparatuses performing wireless communication or more and allocates the frequency division to each communication terminal apparatus. A method is adopted in which a pilot symbol is multiplied by a spreading code in the allocated frequency band and transmitted.

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.

The propagation path estimation method of the present invention employs a method of allocating a plurality of frequency bands for transmitting pilot symbols to each communication terminal.

According to the propagation path estimation method of the present invention, a base station apparatus estimates propagation paths of a plurality of frequency bands in which pilot symbols are transmitted from a communication terminal apparatus, and interpolates the estimation results to generate pilot symbols. A method of estimating the propagation path of the frequency band not transmitted 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 in which the base station apparatus removes interference due to signals other than the desired pilot symbols from the received signal and estimates the propagation path from the interference-removed signal.

According to this method, it is possible to remove interference caused by a signal transmitted from the base station itself and interference from a mobile terminal other than the target mobile terminal.

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

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 apparatus
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 the propagation path estimated by any one of the propagation path estimation methods described above.

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.

[0045]

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

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 a communication terminal in a frequency band (f2) unique to the downlink. Further, the signal converted to the frequency band (f2) is transmitted to the communication terminal.

Duplexer 152 outputs a reception signal received by antenna 151 to reception RF section 153, and outputs a transmission signal output from transmission RF section 160 to antenna 151.

The reception RF section 153 performs amplification processing, frequency conversion processing, and the like on the signal received by the antenna 151 to extract a baseband signal. Interference canceller 154
Removes interference due to signals other than the desired pilot symbols from the output signal of the reception RF section 153.

The despreading unit 155 includes an interference canceller 154
Performs a despreading process of multiplying the baseband signal output from the baseband signal by a spreading code to extract a pilot symbol. Propagation path estimating section 156 performs equalization processing on pilot symbols output from despreading section 155 to estimate a propagation path.

Modulation section 157 applies QP to transmission data.
A modulation process such as SK is performed. The precoder 158 converts the inverse characteristic of the propagation path estimated by the propagation path estimation section 156 into the modulation section 1
A process (precoding) of multiplying by the output signal of 57 is performed. Spreading section 159 performs spreading processing for multiplying the transmission signal output from precoder 158 by a spreading code, and outputs a baseband signal. Transmission RF section 160
Performs amplification processing, frequency conversion processing, and the like on the output signal of the spreading section 159, and outputs a signal in the frequency band (f2).

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 in the frequency band (f2) unique to the downlink. The base station also transmits the signal whose frequency has been converted to the frequency band (f2) to the base station.

Duplexer 252 outputs a reception signal received by antenna 251 to reception RF section 253, and transmits a transmission signal output from transmission RF section 259 to antenna 251.
Output to

The reception RF section 253 performs amplification processing, frequency conversion processing, and the like on the signal received by the antenna 251 and outputs a baseband signal. Interference canceller 254
Removes interference due to signals other than the desired signal from the output signal of the reception RF unit 253.

The despreading unit 255 includes an interference canceller 254
Performs a despreading process of multiplying the baseband signal output from the baseband signal by a spreading code to extract a received signal. Demodulation unit 2
56 performs demodulation processing on the received signal output from the despreading unit 255 to extract received data.

Further, pilot symbol generating section 257
Generates pilot symbols used for estimating the propagation path at the base station. Spreading section 258 performs spreading processing for multiplying the pilot symbol output from pilot symbol generating section 257 by a spreading code, and outputs a baseband signal. RF transmitting section 259 performs amplification processing, frequency conversion processing, and the like on the baseband signal output from spreading section 258, and outputs a signal in 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 203
Is transmitted wirelessly to the base station.

The signal in the frequency band (f 1) wirelessly transmitted from the communication terminal is received by antenna 101 of the base station, amplified by reception RF section 102, frequency-converted to baseband, and demodulated by 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 the modulator 1
57, pre-coded by precoder 158, spread by spreading section 159, and transmitted RF section 160
And is frequency-converted to the frequency band (f2),
The signal is wirelessly transmitted from the antenna 151 to the communication terminal via the duplexer 152.

The signal in the frequency band (f 2) wirelessly transmitted from the base station is received by the antenna 251 of the communication terminal, and received by the reception RF section 253 via the duplexer 252.
, Is amplified by the reception RF section 253, frequency-converted to baseband, and interference by signals other than the desired signal is removed by the interference canceller 254. The despreading section 255
, And demodulated by the demodulation unit 256 to extract data.

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

[0068] Pilot symbol generation section 25 of communication terminal
7 is spread by the spreading section 258, amplified by the transmission RF section 259, frequency-converted to a frequency band (f2), and transmitted wirelessly from the antenna 251 to the base station via the duplexer 252. Is done.

The signal in the frequency band (f 2) wirelessly transmitted from the communication terminal is received by the antenna 151 of the base station, and is received via the duplexer 152 by the reception RF section 153.
, Is amplified by the reception RF section 153, frequency-converted to baseband, interference by signals other than desired pilot symbols is removed by the interference canceller 154, despread by the despreading section 155, and propagation path estimation is performed. Part 156
Is input to The propagation path estimation unit 156 performs an equalization process using pilot symbols, and estimates a propagation path.

Next, the relationship between signal types and codes in each frequency band (f1, f2) will be described with reference to FIG.

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), downlink data transmitted from the base station to the communication terminal and pilot symbols transmitted from the communication terminal to the base station are transmitted.

In FIG. 3, the signal power Pd is the power of the downlink signal transmitted from the base station, and the signal power Pp is
This is the power of a signal obtained by modulating a pilot symbol transmitted from a communication terminal.

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
According to the CDD scheme in which pilot symbols are spread and transmitted using codes known between apparatuses, the base station can estimate a propagation path based on the immediately preceding pilot symbols obtained by despreading, and transmit signals by precoding. Can be compensated for.

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, the case where the radio channel for transmitting the pilot symbol is divided by each system will be described.
This will be described with reference to FIG.

FIG. 4A shows a case where a radio channel is divided by the TDMA method, and FIG.
FIG. 4 shows a case where a wireless channel is divided according to a method.
(C) shows a case where a wireless channel is divided by the CDMA method.

In the case of the TDMA system, as shown in FIG. 4A, a slot for permitting transmission of a pilot symbol is assigned to each communication terminal, and each communication terminal (u1, u2... U)
n) transmit pilot symbols in the assigned time slots.

In the case of the FDMA system, FIG.
As shown in (b), the frequency band (f2) is divided by the number of communication terminals, and each communication terminal (u1, u2... Un) transmits a pilot symbol in each of the divided bands.

In the case of the CDMA system, FIG.
As shown in (c), each communication terminal (u1, u2... Un) transmits a pilot symbol multiplied by a unique spreading code.

As described above, the radio channel is divided by any of the above-mentioned methods, and each communication terminal transmits a pilot symbol using the allocated radio channel, so that the base station transmits a propagation path for each communication terminal. Can be estimated.

A radio channel for transmitting pilot symbols can be divided by mixing two or more of the above methods. FIG. 5 shows a case where the FDMA system and the CDMA system are mixed.

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 156.
Weighting is performed on signals transmitted and received from -1 to 151-n.

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

The receiving 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 adding section 162,
A pilot symbol is extracted by performing frequency conversion processing and the like. Interference canceller 154 removes interference due to signals other than desired pilot symbols from the output signal of reception RF section 153.

The despreading unit 155 includes an interference canceller 154
Performs a despreading process of multiplying the baseband signal output from the baseband signal by a spreading code to extract a pilot symbol. Propagation path estimation section 156 performs equalization processing based on pilot symbols output from despreading section 155 to estimate a propagation path. The propagation path estimation unit 156 controls the weighting units 161-1 to 161-n based on the estimated propagation path.

[0089]

As described above, according to the base station apparatus and the propagation path estimating method of the present invention, the communication terminal spreads pilot symbols with a code known between the apparatuses and transmits the pilot symbols. , Despreads the previous pilot symbol,
Since the propagation path can be estimated based on this, in a wireless communication system in which the frequency bands of the uplink and the downlink are asymmetric, the propagation path of the downlink can be estimated effectively.

[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 diagram illustrating a division scheme of a radio channel for transmitting pilot symbols according to the above embodiment.

FIG. 5 is a diagram illustrating a method of dividing a radio channel for transmitting pilot symbols according to the above embodiment.

FIG. 6 is a diagram illustrating a division scheme of a radio channel for transmitting pilot symbols according to the embodiment.

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

[Explanation of symbols]

 101, 151, 203, 251 Antenna 102, 153, 253 Receiving RF unit 103, 256 Demodulation unit 155, 255 Despreading unit 156 Propagation path estimation unit 157, 201 Modulation unit 158 Precoder 159, 258 Spreading unit 160, 202, 259 Transmission RF unit 161 Weighting unit 162 Addition unit 257 Pilot symbol generation unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K022 EE01 EE35 5K046 EE06 EE47 EF05 EF15 5K067 CC10 DD01 DD25 EE02 EE10 EE22 GG01 GG11 KK03

Claims (22)

[Claims] 1. A communication terminal apparatus, and a base station apparatus for performing wireless communication with asymmetrical uplink and downlink frequency bandwidths, wherein a spreading code is transmitted from the communication terminal apparatus in the same frequency band as the downlink. Despreading means for performing despreading processing on pilot symbols transmitted by multiplication, and propagation path estimating means for estimating a propagation path based on pilot symbols output from the despreading means. Base station device. 2. The communication apparatus according to claim 1, wherein the frequency band of the downlink is time-divided by the number of communication terminal apparatuses for wireless communication or more than that and assigned to each communication terminal apparatus.
The base station device as described in the above. 3. The downlink frequency band is code-divided by the number of communication terminal devices performing wireless communication or more and assigned to each communication terminal device.
The base station device as described in the above. 4. The base station apparatus according to claim 2, wherein a part of a downlink frequency band is assigned to each communication terminal apparatus performing wireless communication. 5. The base station apparatus according to claim 1, wherein the frequency band of the downlink is frequency-divided by the number of communication terminal apparatuses performing wireless communication or more than that and assigned to each communication terminal apparatus. . 6. The base station apparatus according to claim 4, wherein a plurality of frequency bands for transmitting pilot symbols are assigned to each communication terminal. 7. A propagation path estimating unit 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 a frequency band in which a pilot symbol is not transmitted. The base station apparatus according to any one of claims 4 to 6, wherein a propagation path is estimated. 8. The apparatus according to claim 1, further comprising: interference canceling means for removing interference caused by signals other than the desired pilot symbols from the received signal; and propagation path estimating means for estimating a propagation path from the interference-eliminated signal. The base station device according to any one of claims 1 to 7. 9. 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 the transmission data. 2. The base station device according to 1. 10. 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 9, further comprising a weighting means for performing the operation. 11. A communication, characterized in that a pilot symbol is multiplied by a spreading code in the same frequency band as a downlink and transmitted to the base station apparatus according to any one of claims 1 to 10. Terminal device. 12. The communication terminal device according to claim 11, further comprising interference canceling means for removing interference caused by a signal other than a desired signal from the received signal. 13. When performing wireless communication in which the uplink and downlink frequency bandwidths are asymmetric, a spreading code is applied to a pilot symbol from a communication terminal apparatus to a base station apparatus in the same frequency band as the downlink. A multipath transmission method, wherein the base station apparatus despreads the received pilot symbols and estimates a propagation path based on the despread pilot symbols. 14. A base station apparatus according to claim 1, wherein the base station apparatus divides the time by the number of communication terminal apparatuses performing wireless communication or more and allocates each of the communication terminal apparatuses to a pilot symbol at a time when the communication terminal apparatus is allocated. 14. The propagation path estimation method according to claim 13, wherein the transmission is performed by multiplying by a spreading code. 15. A base station apparatus divides a code by the number of communication terminal apparatuses performing wireless communication or more and allocates the divided code to each communication terminal apparatus, and assigns the code assigned to each communication terminal apparatus to a pilot symbol. 14. The propagation path estimation method according to claim 13, wherein the transmission is performed by multiplying. 16. A base station apparatus allocates a part of a downlink frequency band to each communication terminal apparatus performing wireless communication, and uses each of the communication terminal apparatuses to allocate a pilot symbol using a part of the allocated downlink frequency band. 16. The propagation path estimating method according to claim 14, wherein a signal obtained by multiplying the signal by a spreading code is transmitted. 17. The base station apparatus divides a frequency by the number of communication terminal apparatuses performing wireless communication or more and allocates the frequency division to each communication terminal apparatus, and a pilot symbol in a frequency band to which the communication terminal apparatus is allocated. 17. The propagation path estimating method according to claim 16, wherein the signal is multiplied by a spreading code and transmitted. 18. The propagation path estimation method according to claim 16, wherein a plurality of frequency bands for transmitting pilot symbols are assigned to each communication terminal. 19. A base station apparatus estimates propagation paths of a plurality of frequency bands in which pilot symbols are transmitted from a communication terminal apparatus, and interpolates the estimation results to estimate a propagation path of a frequency band in which no pilot symbols are transmitted. 19. The propagation path estimation method according to claim 16, wherein the propagation path is estimated. 20. The base station apparatus according to claim 13, wherein the base station apparatus removes interference due to a signal other than a desired pilot symbol from the received signal, and estimates a propagation path from the interference-removed signal. The propagation path estimation method according to any one of the above. 21. 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 13 to 20. Inverse processing method. 22. The base station apparatus transmits and receives signals from a plurality of antenna elements forming an array antenna.
21. 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 3 to 20.