JP5652609B2 - Wireless communication system and propagation path information acquisition method - Google Patents

Description

  The present invention relates to a radio communication system, and more particularly, to a radio communication system using a pilot signal.

  A wireless communication method using a pilot signal is described in Patent Document 1, for example. The wireless communication system described in Patent Document 1 notifies a pilot signal from a base station to a terminal located in a cell, and establishes communication and improves communication quality using the pilot signal. Yes. The base station of the radio communication system can transmit a plurality of patterns of pilot signals, and determines a pattern to be transmitted according to the cell environment.

  Further, for example, Patent Document 2 and Patent Document 3 describe wireless communication methods that improve communication quality by constructing a feedback loop between the transmission side and the reception side.

  In the wireless communication system described in Patent Document 2, the reception-side wireless communication device estimates information on a propagation path (channel) between wireless communication devices in response to a feedback request from the transmission-side wireless communication device. And a transmission method that is likely to be good for communication based on the estimated information is selected and notified to the wireless communication device on the transmission side. Thereafter, the transmission-side wireless communication device communicates with the reception-side wireless communication device according to the designated transmission method.

  In the wireless communication system described in Patent Literature 3, the user terminal on the reception side estimates the information on the channel (channel) between the access point and the user terminal in response to a feedback request from the access point on the transmission side. The estimated information is notified to the access point on the transmission side as feedback information (downlink propagation path information). Thereafter, the access point communicates with the user terminal on the reception side using a transmission method that would be good for performing communication determined from downlink propagation path information based on the notified feedback information.

  The downlink propagation path information is used in, for example, a base station that transmits by MIMO (Multi Input Multi Output) or beam forming (Beamforming). By using the propagation path information, the base station can transmit a signal with an optimum beam shape and transmission weight according to the state of the propagation path. In order to obtain downlink propagation path information, the downlink propagation path information obtained by the terminal is quantized and fed back to the base station using the uplink.

  A specific example of a pilot signal in the MIMO propagation path is described in Non-Patent Document 1, for example.

Table 2007-125889 JP 2010-081092 A Special table 2008-545293

IEEE std 802.16e-2005

  As described above, when the downlink channel information is fed back from the terminal to the base station, the downlink channel information estimated by the terminal is quantized.

  However, the quantization at the terminal may require several symbols for information feedback to the base station. The propagation path information of several symbols is an overhead required for feedback, which leads to a decrease in uplink transmission rate.

  In addition, it takes time to process the feedback information obtained by performing quantization in the terminal to the base station. For this reason, for example, when the base station obtains the feedback channel information and then calculates and determines the optimum weight and operates based on the weight to transmit the signal, the downlink The actual situation of the propagation path may have already changed, and there is a problem that it deviates from the optimum weight.

In view of the above-described problems, an object of the present invention is to provide a wireless communication system and a propagation path information acquisition method for feeding back propagation path information between a base station and a wireless terminal apparatus at high speed and reducing link overhead. And

The wireless communication system according to the present invention includes a means for transmitting a pilot signal used as a communication reference in the downlink, a first return pilot signal transmitted through the uplink in response to the pilot signal, and a second Means for estimating the propagation path information on the downlink propagation path followed by the pilot signal by comparison operation of the first return pilot signal and the second return pilot signal, and a control signal A method of estimating propagation path information using the first return pilot signal and the second return pilot signal based on the uplink quality acquired by using the radio terminal apparatus, and a base station comprising a method for feedback, and means for selectively adaptively Te, Dow from the base station Means for receiving a pilot signal affected by a propagation path of a link, adding a known value of the base station and transmitting the affected pilot signal as a first return pilot signal; And a radio terminal apparatus comprising: means for transmitting a signal having the same content as the pilot signal transmitted from the terminal as a second return pilot signal in the same frequency band as the first return pilot signal. .

ADVANTAGE OF THE INVENTION According to this invention, the acquisition method of the radio | wireless communications system and propagation path information which feed back the propagation path information between a base station and a radio | wireless terminal apparatus at high speed and less link overhead can be provided.

It is explanatory drawing which shows the structure of the radio | wireless communications system 1 concerning 1st Embodiment. It is explanatory drawing which shows the reference signal used by mobile WiMAX. It is explanatory drawing which shows the structure of the radio | wireless communications system 2 concerning 2nd Embodiment. It is explanatory drawing which shows the structure of the radio | wireless communications system 3 concerning 3rd Embodiment.

  A wireless communication system according to an embodiment of the present invention will be described with reference to FIG. In addition, description is abbreviate | omitted in order to simplify description about a structure with little relation with this invention, or a self-evident structure.

The wireless communication system 1 includes a base station 100 (BS) and a wireless terminal device 200 (MS). BS and MS are names defined for each communication standard, but other wireless stations having various names such as NodoB and UE may be operated similarly.

The base station 100 generates a pilot signal (reference signal) used as a communication reference and transmits the pilot signal, and the received first return pilot signal (first return reference signal) and the second A propagation path information estimation unit 120 that estimates downlink propagation path information from the return pilot signal (second return reference signal) is provided.
The pilot signal is one or a plurality of defined signals that notify a reference timing or signal to other stations defined by the communication standard. For example, a subcarrier arrangement method called DL PUSC (Downlink Partially Used SubChannelization) defined in Mobile WiMAX described in Non-Patent Document 1 is as shown in FIG. Of the 2 × 14 subcarriers, four subcarriers are pilot subcarriers (= reference signal).

  In the LTE communication standard, the reference signal is used as a reference signal.

  In any reference signal, a reference signal used as a pilot is arranged in a frame composed of frequency and time subcarriers, and each reference signal is a predetermined symbol (for example, a BPSK symbol of a random signal). ing. When there are a plurality of antennas, a signal arrangement pattern is prepared for each antenna. At the positions on the time axis and frequency axis of each signal, the standard signals are standardized so as not to interfere with each other by not transmitting subcarriers from other antennas.

  In pilot signal transmission section 110, base station 100 determines for each radio terminal apparatus using a plurality of prepared pilot signals. For example, when the base station 100 establishes a link with the wireless terminal device 200, the content of the determination is notified from the base station 100 to the wireless terminal device 200 as a control signal. For example, if a random sequence such as a PN sequence is prepared, a different pilot signal can be used for each wireless terminal device, and reception is performed even when a pilot signal transmitted from another base station interferes. A desired pilot signal can be detected by correlation on the side.

  Radio terminal apparatus 200 transmits a pilot signal received from base station 100 as a first return pilot signal without being quantized, and a pilot signal return unit 210 having the same contents as the pilot signal received from base station 100. And a pilot signal transmission unit 220 that transmits a signal as a second return pilot signal.

  The pilot signal returning unit 210 receives the pilot signal affected by the received propagation path, and amplifies the signal by adding a known value in an analog wave state without sending it to a digital processing circuit or the like. The first return pilot signal is generated and transmitted from the antenna. The known value may be one type or may be selected from a plurality of types. Alternatively, it may be selected dynamically.

  The pilot signal transmission unit 220 transmits a signal having the same content as the pilot signal transmitted from the base station 100 as the second return pilot signal. Note that the type of pilot signal is notified in advance using a control signal or the like as described above, or is identified from the received pilot signal.

Next, the overall operation of the wireless communication system 1 will be described. The description will be made with reference to symbols in FIG.
A pilot signal P is transmitted from the base station 100. The pilot signal P is a signal known also in the radio terminal device 200. The pilot signal P transmitted from the base station 100 is received by the wireless terminal device 200 in a state of being distorted by the downlink propagation path. At this time, if the distortion of the downlink propagation path is H, the signal received by the wireless terminal device 200 can be expressed as HP.

Next, the wireless terminal device 200 multiplies the received pilot signal HP subjected to distortion by a constant a and transmits it as a first return pilot signal. At this time, the pilot signal return unit 210 that generates the first return pilot signal immediately generates the first return pilot signal from the received pilot signal without performing processing such as quantization. The first return pilot signal to be transmitted may be transmitted by adaptively selecting a high-quality uplink channel, for example, a sub-channel having a good frequency axis quality in the uplink.

The constant a is a known value for adjusting the dynamic range when received by the base station 100, and is set as a coefficient for compensating the amplitude of the pilot signal attenuated in the propagation path. The constant a is used for estimating propagation path information in the base station 100 as described below.
Also, the value of a is known by the base station 100. For example, it is preferable to set so that a≈1 / | H |. At this time, the amplitude of the first return pilot is | aHP | ≈ | P |. Therefore, when this base station receives the first return pilot, a good S / N can be obtained.
Moreover, since the amplitude of H changes according to the situation, it is preferable that the value of a is also changed according to the change of H. For example, a plurality of values of a are prepared in both the base station 100 and each terminal device, and information on which value to use is determined by the base station or the terminal station and transmitted via the control channel. May be.
Note that the value of a is not limited to the above as long as the value can be a known value in the base station 100.

The first return pilot signal aHP transmitted from the wireless terminal device 200 is distorted by the uplink propagation path and received by the base station 100. At this time, assuming that the distortion of the uplink propagation path is H ′, the first return pilot signal S1 subjected to the distortion received by the base station 100 can be expressed as aH′HP.
Here, if the communication frequency and the time can be regarded as substantially the same, the uplink H ′ may be regarded as H and the base station without feeding back the downlink propagation path coefficient H. On the other hand, if the downlink channel coefficient H and the uplink coefficient H ′ are functions of frequency or time, H and H ′ often do not coincide with each other. In particular, in a wireless communication system configured to desire a frequency diversity effect, there is often no coincidence. The same applies to an FDD (Frequency Division Duplex) system and a wireless communication system using a communication system using a number of subcarriers.

A signal having the same content as the pilot signal P transmitted from the base station 100 is transmitted from the wireless terminal device 200 using another slot of the same frame (frequency) as that of the first return pilot signal to the second return pilot signal. Send as a signal. That is, the first return pilot signal and the second return pilot signal are transmitted almost simultaneously in the same frequency band.
At this time, the second return pilot signal is generated by the pilot signal transmission unit 220. The second return pilot signal (pilot signal P) transmitted from radio terminal apparatus 200 is received by base station 100 after receiving uplink propagation path distortion H ′. The second return pilot signal S2 subjected to the distortion received by the base station 100 can be expressed as H′P.

Next, in the base station 100, the propagation path information estimation unit 120 uses the first return pilot signal S1 that has received the distortion received from the radio terminal device 200 and the second return pilot signal S2 that has received the distortion. Estimate downlink propagation path information.
The propagation path information estimation section 120 estimates propagation path information by obtaining a propagation path distortion H by comparing the first return pilot signal S1 that has been distorted and the second return pilot signal S2 that has been distorted.
If the comparison operation is formulated into a mathematical expression, the following expression 1 is obtained. The said formula 1 is a formula which changed S1 and substituted S2. As can be seen from Equation 1, H can be easily calculated from S1 and S2 and a constant a which is a known real constant. The constant a can be dynamically changed by multiplying the second return pilot signal by the wireless terminal device 200. However, the transmission of the second return pilot signal is increased.

Further, the radio terminal apparatus 200 may transmit the first return pilot signal and the second return pilot signal with the respective amplitudes inverted with respect to the time axis. In this way, H can be easily calculated from the first return pilot signal S1 subjected to the respective distortions inverted by the base station 100 and the second return pilot signal S2 subjected to the distortion. The signal waveform is different from the signal, and problems such as interference are less likely to occur.

The propagation path information estimated by operating in this way is used by the base station 100 and the wireless terminal device 200 to improve communication quality. The estimation of the downlink propagation path information with the base station 100 and the wireless terminal device 200 can be fed back at a high speed with little uplink overhead.

In the above, for simplification of description, the method of feeding back downlink propagation path information to the base station side using one antenna at each of the base station 100 and the wireless terminal device 200 has been shown.

  Next, the wireless communication system 2 of the second embodiment will be described with reference to FIG.

In the first embodiment, the method of feeding back the propagation path information in the configuration of the antenna of one base station 100 and the antenna of one terminal apparatus 200 has been described.
However, in a wireless communication system that uses downlink propagation path information in a base station, there are cases where beam forming is performed on the transmission side and MIMO communication such as eigenmode transmission is performed. Beam forming is a necessary condition that a plurality of base station antennas are used. Also, MIMO is a necessary condition that both the base station and the terminal antennas are plural.
Therefore, in the second embodiment, a case where there are a plurality of antennas for the base station and a plurality of antennas for the terminal device is shown. In the following description, it is assumed that the base station has M antennas and the terminal apparatus has N antennas.

  The wireless communication system 2 includes a base station 300 (BS) and a wireless terminal device 400 (MS).

  Base station 300 generates a pilot signal transmitted from each antenna and generates a pilot signal transmitting section 310, and from each of the first return pilot signal and second return pilot signal received from each antenna, A propagation path information estimation unit 320 for estimating downlink propagation path information communicated via

  Radio terminal apparatus 400 transmits a pilot signal received from base station 300 via each antenna as a first return pilot signal without being quantized, and a pilot signal return unit 410 via each antenna. A pilot signal transmission unit 420 that transmits a signal having the same content as the pilot signal received from the base station 300 as a second return pilot signal is provided.

  When communication is performed using a plurality of antennas in the wireless communication system 2, a plurality of propagation paths are formed. When M antennas are used in the base station 300 and N antennas are used in the wireless terminal device 400, M × N propagation paths (MIMO transmission paths) can be defined. By acquiring the respective propagation path information for M × N propagation paths, the communication quality between the base station 300 and the terminal device 400 can be improved. When a plurality of antennas are used, pilot signals transmitted from the respective antennas are handled so as to be separable on the receiving side by being assigned in advance or notified.

  Next, the operation of the wireless communication system 2 will be described.

From the base station 300, the respective pilot signals P1 to _M are transmitted from the respective antennas. Pilot signals P 1 to _M are also known in radio terminal apparatus 400. Pilot signals P 1 to _M transmitted from base station 300 are distorted by the respective downlink propagation paths and received by radio terminal apparatus 200.

Next, the terminal device 400 adds a known value to each received pilot signal subjected to distortion, and transmits the result as a first return pilot signal, and the same contents as the received pilot signals P 1 to _M. Are transmitted from each antenna as a second return pilot signal.
At this time, the terminal device 400 may adaptively select a high-quality antenna and transmit the first and second return pilots.
As shown in the first embodiment, a change such as transmission may be made by adding the same known value as that of the first return pilot signal to the second return pilot signal.

Next, in the base station 300, the propagation path information estimation unit 320 transmits each first return pilot signal and second transmission signal transmitted from the terminal device 400 and received from a predetermined antenna for each MIMO propagation path to be used as appropriate. The downlink propagation path information traced by the pilot signals P 1 to _M is estimated from the returned pilot signal.

Here, when attention is paid to downlink coefficients and uplink coefficients h ₁₁ and h ′ ₁₁ in the propagation path between the antenna 1 of the base station 300 and the antenna 1 of the wireless terminal apparatus 400 in the MIMO propagation path, the coefficients h ₁₁ and h _'11, the coefficient H of the downlink of the first embodiment to h _11, the coefficient H of the propagation path of the uplink' can be regarded as a to h _'11.

That is, in the transmission method of the same pilot signal and the first embodiment, a propagation path distortion h ₁₁ can be fed back to the base station 300 can acquire the channel information about the propagation path distortion h ₁₁ (see FIG. 3) .

Similarly, for other h _nm , the channel distortion h _nm can be obtained by performing a comparison operation using the first return pilot signal S _{1 nm} and the second return pilot signal S _{2 nm} that has been distorted. Here, _n and _m indicate the m-th antenna of the base station 300 and the n-th antenna of the wireless terminal device 400, respectively.

  Equation 2 showing the distortion of each propagation path of the MIMO propagation path is shown in Equation 2 below.

In FIG. 3, the propagation path distortion h _NM corresponding to the last MIMO propagation path is shown in the same manner as the propagation path distortion h ₁₁ . The propagation path distortion h _NM is propagation path information of a MIMO propagation path that falls between the Mth antenna of the base station 300 and the Nth antenna of the wireless terminal device 400. Note that other propagation path distortions are omitted from the drawing.

  Each estimated MIMO propagation path information is used by the base station 300 and the terminal device 400 to improve communication quality.

  In the present embodiment, the base station and the terminal device have been described with respect to the one-to-one MIMO communication. However, the one-to-many MIMO communication (multi-user MIMO), the many-to-one communication, and the like are similarly performed for each propagation path. The channel information can be fed back by sending back the first return pilot signal and the second return pilot signal.

  That is, it is possible to acquire the propagation path information between the wireless device that transmits the reference signal and the wireless device that receives the reference signal at high speed and with less overhead required for feedback.

  Next, the wireless communication system 3 according to the third embodiment will be described with reference to FIG.

  The wireless communication system 3 includes a base station 500 (BS) and a wireless terminal device 600 (MS).

  The base station 500 includes a quality measurement unit 530 and a feedback method selection unit 540 in addition to the same configuration (pilot signal transmission unit 510, propagation path information estimation unit 520) as the base station 100 of the first embodiment.

  The quality measuring unit 530 operates as means for measuring uplink quality. For example, the S / N ratio is used as the quality.

  The feedback method selection unit 540 adaptively selects the feedback method in the wireless terminal device 600 according to the information indicating the quality from the quality measurement unit 530.

  In addition to the same configuration (pilot signal returning unit 610, pilot signal transmitting unit 620) as the wireless terminal device 200 of the first embodiment, the wireless terminal device 600 quantizes the downlink propagation path information and feeds back the method. It has a channel information quantization feedback unit 630 to perform, and selects a method for feeding back channel distortion according to the feedback method instruction from base station 500.

  Propagation path information quantization feedback section 630 includes an estimation section that estimates propagation path distortion based on a received signal, a section that feeds back an estimated value to base station 500, and the like.

Next, the overall operation of the wireless communication system 3 will be described.
Base station 500 acquires communication quality from radio terminal apparatus 600 using a control signal or the like. Based on the acquired communication quality, the base station 500 selects the feedback method described in the first embodiment when the uplink communication quality (S / N ratio or the like) is good. On the other hand, when the uplink quality is poor, a method of quantizing the downlink propagation path information and feeding back is selected. The base station 500 notifies the wireless terminal device 600 of the selected method.

  Thereafter, the wireless communication system 3 performs feedback on the distortion of the downlink propagation path based on the selected method.

  By operating in this way, certainty that the propagation path information can be acquired on the base station side is improved.

  Although the present embodiment has been described using the first embodiment, it can be similarly applied to the MIMO communication shown in the second embodiment, and can contribute to the improvement of communication quality. Also, the base station uses a downlink propagation path information estimated or acquired, and a beamforming determining unit that performs beamforming using a plurality of antennas and a transmission weight determining unit that determines a transmission weight of MIMO communication. You may make it operate.

  Next, the effect will be described.

1) Since downlink channel information can be fed back with one symbol without being quantized, overhead for feeding back channel information can be reduced. That is, there is an effect of improving communication throughput.

2) Since the received pilot signal is transmitted almost as it is in the wireless terminal device, the amount of calculation in the wireless terminal device can be reduced.

3) Furthermore, since there are few processes in the wireless terminal device, the feedback time can be shortened. That is, it is possible to reduce deterioration of communication quality due to a time change of the propagation path from when the base station transmits the pilot signal until transmission using the propagation path information. In other words, communication quality can be greatly improved in a propagation path with a large time change.
The present invention can be used in various wireless communication systems such as a mobile communication system and a fixed communication system. In particular, in a radio communication system that uses frequency division duplexing and similarly a plurality of frequency bands, a great effect is achieved when transmission beamforming and eigenmode transmission are performed.
Also, a great effect can be expected when the wireless terminal device is moving.

  Further, in the same signal processing method, the base station transmits the first return reference signal and the second return reference signal using the reference signal transmitted from the wireless terminal device, and the uplink propagation is performed on the wireless terminal device side. Road information can also be estimated.

  Also, one wireless station may have both means on the transmission side and reception side. This configuration is suitable for a radio station that can form a mesh type or tree type network. Further, propagation path information can be used for network construction.

  As described above, according to the present invention, according to the present invention, the radio communication system and the propagation that feed back the propagation path information between one radio station and another radio station at high speed and with low link overhead. A method for acquiring road information can be provided.

  In addition, what is necessary is just to implement | achieve each part of a radio | wireless communications system suitably using the combination of hardware and software. In a form in which hardware and software are combined, the hardware may be operated by software so that the base station or the wireless terminal device realizes the feedback method described above. For example, the feedback program is developed in the RAM, and the control unit (CPU) of each device is operated as various means based on the program.

  Moreover, the said embodiment can be combined suitably.

  In addition, the specific configuration of the present invention is not limited to the above-described embodiment, and changes within a range not departing from the gist of the present invention are included in the present invention.

In addition, a part or all of the above-described embodiments can be described as follows. Note that the following supplementary notes do not limit the present invention.
[Appendix 1]
A means for transmitting a reference signal used as a communication reference, and a propagation path related to the propagation path followed by the reference signal from the first return reference signal and the second return reference signal sent back in response to the reference signal A first wireless station comprising means for estimating information;
Means for receiving a reference signal affected by a propagation path from the first radio station, adding a known value and transmitting the affected reference signal as a first return reference signal; A second wireless station comprising means for transmitting a signal having the same content as the reference signal transmitted from the first wireless station as a second return reference signal;
A wireless communication system for estimating propagation path information.

[Appendix 2]
A base station comprising means for transmitting a pilot signal, and means for comparing and calculating a first return pilot signal and a second return pilot signal received via the uplink to estimate downlink propagation path information;
Means for transmitting a pilot signal received from the base station via the downlink as a first return pilot signal without quantization; and a signal having the same content as the pilot signal received from the base station A wireless terminal device comprising means for transmitting as a return pilot signal;
Composed by
In the base station, a pilot signal is transmitted,
In the wireless terminal device, the pilot signal influenced by the received downlink propagation path is transmitted as the first return pilot signal without being quantized, and the pilot signal transmitted from the base station and A similar signal is transmitted as the second return pilot signal,
The propagation according to the above supplementary note, wherein the base station estimates downlink propagation path information based on the first and second return pilot signals affected by the received uplink propagation path. A wireless communication system that feeds back route information.

[Appendix 3]
The wireless communication system according to the above supplementary note, wherein the base station includes a plurality of antennas and is capable of estimating propagation path information for each propagation path.

[Appendix 4]
The base station includes means for enabling beamforming to be determined using estimated channel information and / or means for determining a transmission weight used for MIMO communication. Wireless communication system.

[Appendix 5]
The base station and the wireless terminal device communicate with each other using an FDD (Frequency Division Duplex) method.

[Appendix 6]
The wireless communication system according to the above supplementary note, wherein the wireless terminal device includes a plurality of antennas and is capable of transmitting a first return pilot signal and a second return pilot signal for each propagation path.

[Appendix 7]
The wireless communication system according to the above supplementary note, wherein the wireless terminal device adaptively selects and transmits a high-quality antenna when transmitting the first and second return pilots.

[Appendix 8]
The base station estimates propagation path information using the first return pilot signal and the second return pilot signal based on the uplink quality acquired using the control signal, and the radio terminal apparatus The wireless communication system as described in the above supplementary note, comprising means for adaptively selecting a method for quantizing and feeding back information relating to a propagation path.

[Appendix 9]
The wireless communication system according to the above supplementary note, wherein the wireless terminal device adaptively selects a high-quality channel for transmission when transmitting the first and second return pilots.

[Appendix 10]
Transmitting a predetermined reference signal used as a communication reference from the first wireless station;
The second radio station on the receiving side receives the reference signal affected by the received propagation path, adds a known value, and transmits the affected reference signal as the first return reference signal. And transmitting a signal having the same content as the predetermined reference signal as a second return reference signal,
The first wireless station estimates and acquires propagation path information regarding the propagation path between the wireless stations followed by the reference signal from the first return reference signal and the second return reference signal sent back. A method for acquiring propagation path information.

[Appendix 11]
A pilot signal from the base station,
In the terminal, the pilot signal affected by the received downlink propagation path is transmitted as the first return pilot signal without being quantized, and the same content as the pilot signal transmitted from the base station. As a second return pilot signal,
The propagation according to the above supplementary note, wherein the base station estimates downlink propagation path information based on the first and second return pilot signals affected by the received uplink propagation path. How to get road information.

[Appendix 12]
The base station includes a plurality of antennas, and estimates propagation path information for each propagation path.

[Appendix 13]
The base station uses the estimated propagation path information to determine beamforming, and the propagation path information acquisition method according to the above supplementary note, characterized in that:

[Appendix 14]
The base station uses the estimated propagation path information to determine a transmission weight to be used for MIMO communication.

[Appendix 15]
The base station and the wireless terminal device communicate a pilot signal, a first return pilot signal, and a second return pilot signal using an FDD (Frequency Division Duplex) method. How to get road information.

[Appendix 16]
The wireless terminal apparatus includes a plurality of antennas, and transmits a first return pilot signal and a second return pilot signal for each propagation path.

[Appendix 17]
The wireless terminal apparatus adaptively selects and transmits a high-quality antenna when transmitting the first and second return pilots, and acquires the propagation path information according to the above supplementary note. .

[Appendix 18]
The base station estimates propagation path information using the first return pilot signal and the second return pilot signal based on the uplink quality acquired using the control signal, and the radio terminal apparatus The method of acquiring propagation path information as described in the above supplementary note, wherein a method of adaptively selecting a method for quantizing and feeding back information related to a propagation path is performed by the wireless terminal apparatus.

[Appendix 19]
The wireless terminal apparatus adaptively selects and transmits a channel of good quality when transmitting the first and second return pilots, and acquires the propagation path information according to the above supplementary note. .

[Appendix 20]
Means for transmitting a reference signal used as a communication reference;
A first return reference signal, which is transmitted from another wireless station that has received the reference signal, and which is obtained by adding a known value to the reference signal affected by the propagation path, and a signal having the same content as the reference signal A radio station for estimating propagation path information, comprising: means for estimating propagation path information related to a propagation path followed by the reference signal from a second return reference signal.

[Appendix 21]
A reference signal used as a communication reference is transmitted and a propagation path information is received from a radio station that receives a reference signal that is received under the influence of the propagation path. Means for transmitting a reference signal as a first return reference signal;
Means for receiving propagation of the reference signal, and means for transmitting a signal having the same content as the reference signal transmitted from the wireless station as a second return reference signal. Bureau.

[Appendix 22]
Means for transmitting a reference signal used as a communication reference;
Means for adding a known value to the reference signal affected by the received propagation path and transmitting it as a first return reference signal when receiving a reference signal from another wireless station;
Means for receiving the reference signal and transmitting a signal having the same content as the reference signal transmitted from the other radio station as a second return reference signal;
Means for estimating propagation path information related to the propagation path followed by the reference signal transmitted by itself from the first return reference signal and the second return reference signal transmitted according to the reference signal transmitted by itself. A radio station that estimates propagation path information.

1, 2, 3 Wireless communication system 100, 300, 500 Base station (first wireless station)
110, 310, 510 Pilot signal transmitter (reference signal transmitter)
120, 320, 520 Propagation path information estimation unit 200, 400, 600 Wireless terminal device (second wireless station)
210, 410, 610 Pilot signal return section (reference signal return section)
220, 420, 620 Pilot signal transmitter (reference signal transmitter)
530 Quality measurement unit 540 Feedback method selection unit 630 Channel information quantization feedback unit

Claims (1)

Means for transmitting a pilot signal used as a communication reference in the downlink, and receiving the first return pilot signal and the second return pilot signal sent back via the uplink in response to the pilot signal; Means for estimating propagation path information on the downlink propagation path followed by the pilot signal by comparison operation of the first return pilot signal and the second return pilot signal, and the uplink quality obtained using the control signal And a method for estimating propagation path information using the first return pilot signal and the second return pilot signal and a method for causing the wireless terminal apparatus to quantize and feed back the information on the propagation path. A base station comprising means for selecting ;
Means for receiving a pilot signal affected by a downlink propagation path from the base station, adding a known value of the base station and transmitting the affected pilot signal as a first return pilot signal; And a radio terminal apparatus comprising: means for transmitting a signal having the same content as the pilot signal transmitted from the base station as a second return pilot signal in the same frequency band as the first return pilot signal;
A wireless communication system for estimating propagation path information .

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