CN106411457B - Channel state information acquisition method, feedback method, base station and terminal - Google Patents
Channel state information acquisition method, feedback method, base station and terminal Download PDFInfo
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Abstract
The application provides a channel state information acquisition method, which comprises the following steps: a transmitting terminal transmits a first detection signal and a second detection signal in at least one detection interval; receiving channel state information obtained based on the measurement of the first and second sounding signals from a receiving end; wherein the channel state information comprises one or more of the following information: beam width information, adaptively quantized channel direction information, predicted channel quality information. The application also provides a channel state information feedback method, a base station and a terminal. By applying the method and the device, signaling overhead for channel state information feedback between the base station and the terminal can be reduced, and the base station is prevented from acquiring invalid channel state information.
Description
Technical Field
The present application relates to the field of wireless communication technologies, and in particular, to a channel state information acquisition method, a feedback method, a base station, and a terminal.
Background
A Multiple-Input Multiple-Output (MIMO) technology is one of important technologies for cellular communication, because it can improve the spectral efficiency of a wireless communication system by a Multiple by using spatial resources. However, in order to obtain the corresponding spectral gain, the transmitter must know Channel Direction Information (CDI) in order to calculate precoding and perform other MIMO signal processing. The CDI and the Channel Quality Information (CQI) form complete Channel State Information (CSI). For MIMO systems, accurate CDI acquisition by the transmitter is a prerequisite for closed-loop MIMO transmission and is also critical to system performance.
A Long Term Evolution (LTE) system corresponding to an Evolved Universal Radio Access (E-UTRA) protocol established by a third Generation Partnership Project (3rd Generation Partnership Project, 3GPP) has different CDI acquisition modes according to different duplex modes. Duplex modes of LTE include: time Division Duplexing (TDD) and Frequency Division Duplexing (FDD).
In the TDD system, the uplink channel and the downlink channel have symmetric characteristics. Therefore, the TDD base station performs channel estimation on the uplink channel to obtain the equivalent CDI of the required downlink channel. To assist in channel estimation, a terminal transmits an omnidirectional Sounding Reference Signal (SRS), which is generated using a specific pseudo-random sequence, such as a Zadoff-chu (zc) sequence, known to both the terminal and the base station. The biggest disadvantage of the TDD system in acquiring CDI based on SRS transmission and channel estimation is the pilot pollution (pilot contamination) problem. In an LTE system, SRSs allocated to different terminals in the same cell are orthogonal, so that a base station can perform interference-free channel estimation according to SRS sequences of different terminals to obtain CDI of an uplink channel. However, in the LTE system, SRS sequences allocated to terminals of different cells are non-orthogonal, and even a case where a plurality of terminals use the same SRS sequence, so-called SRS collision problem, may occur. When the SRS conflicts, the base station estimates the uplink channel CDI of the terminal of the cell and receives uplink SRS signals of other cell terminals, therefore, the channel CDI of the cell estimated by the base station also aliasing the channel CDI from other cell terminals to the base station. This phenomenon is known as the pilot pollution problem. The pilot pollution has serious consequences on the uplink and downlink data transmission of the system: 1) when a base station transmits data to a desired terminal by using directional precoding in a downlink channel, the directional data is transmitted to a terminal in an adjacent cell located on an alias channel and becomes serious inter-cell interference; 2) when the base station receives data by post-processing with directivity on an uplink channel for a desired terminal, data of a terminal of an adjacent cell located on an alias channel is also subjected to enhancement processing, thereby amplifying interference of the alias channel. For the above reasons, the pilot pollution problem severely limits the system capacity. Especially when the number of antennas increases, the performance of the system is easy to be improved.
Large-scale antenna array systems (Large-scale MIMO, or Massive MIMO) are fifth generation (5)thGeneration, 5G for short) is the leading candidate for cellular communication standards. The large-scale antenna enables the system to greatly reduce the interference between terminals and the interference between cells by utilizing abundant signal processing freedom degrees, has low calculation complexity and can effectively improve the quality of a communication link. In addition, the large-scale antenna can effectively reduce the power consumption of a single antenna unit and improve the energy efficiency of the whole system. Existing experiments have fully demonstrated the feasibility of configuring tens or even hundreds of antennas for a base station. A specific implementation manner in the millimeter wave band is as follows: the base station forms extremely narrow transmitting wave beams to serve a plurality of terminals by configuring a large-scale antenna array and utilizing phase differences among antennas when the distance between the antennas is small; meanwhile, the terminal can also be configured with a plurality of antennas, different gains are formed for different incoming wave directions, and a receiving beam with larger gain is selected for data receiving. If each transmission beam of the base station serves one terminal, the interference between the terminals is greatly reduced; if the neighboring base stations serve the respective terminals with transmission beams in different directions, the inter-cell interference is greatly reduced. Theoretical analysis results show that, in a large-scale antenna system, if a transmitter knows an accurate terminal channel CDI, signal-to-noise ratio (SNR) of an uplink channel and a downlink channel is increased along with the increase of the number of antennas; the system capacity can be correspondingly and remarkably improved for dozens or even hundreds of transmitting antennas. However, when the pilot pollution problem occurs, the actual capacity of the large-scale antenna system is severely reduced, and even if the base station transmission power is low, the entire system operates in an interference limited state. Problem of pilot pollutionThe impact on a large-scale antenna system is fatal. Therefore, designing a new CDI acquisition mode to overcome the problem of pilot pollution in large-scale antenna systems is of great significance to improve system capacity.
In the FDD system, the uplink and downlink channels are in different frequency bands and have no symmetry, so the base station cannot obtain the downlink channel CDI by estimating the uplink channel. In this case, the terminal must occupy a part of the uplink channel resources to feed back the downlink channel CDI and CQI to the base station. One method is to display feedback, the terminal quantizes the downlink channel CDI by using a fixed codebook and performs multi-level quantization on CQI, and reports the quantization result to the base station through an uplink channel; the other method is hidden feedback, the terminal selects a desired precoding from a plurality of fixed precodes according to the CDI of the downlink channel, and reports the selection result and the CQI under the selected CDI to the base station through the uplink channel. In order to implement the above method, the base station needs to precode the reference signals through different CDIs, and the terminal measures the different reference signals to obtain the signal strength under the corresponding CDIs and determine the CQI. Whichever method is used, in order for a base station to acquire sufficiently accurate downlink channel CSI in an FDD system, the system must incur two necessary overheads: reference signal overhead and feedback overhead. At the same time, both overheads must increase as the number of base station antennas increases. And higher feedback quantization accuracy also means higher overhead. This conclusion means that the way that the FDD system acquires CDI based on feedback faces the challenge of how to efficiently reduce overhead in a large-scale antenna system.
Another important issue is how to precode the downlink data channel based on the CDI due to the CDI measurement error and the feedback delay. If the CDI feedback accuracy is poor and the terminal is in a high-speed moving situation, the downlink data of the base station may deviate from the optimal channel direction, thereby causing the system performance to be degraded.
In summary, in the design of the 5G communication system, the CDI acquisition problem of the large-scale antenna array system is more urgent. A quick and effective CDI acquisition method is designed, so that the reference signal and signaling overhead of the system can be effectively reduced, the probability of using wrong CDI by a base station is avoided, the spectrum gain brought by a large-scale antenna is ensured, and the system capacity of a cell is improved.
Disclosure of Invention
Therefore, the application provides an acquisition method, a feedback method, a base station and a terminal of channel state information, so as to reduce signaling overhead and avoid the base station acquiring invalid channel state information.
The channel state information acquisition method provided by the application comprises the following steps:
a transmitting terminal transmits a first detection signal and a second detection signal in at least one detection interval;
receiving channel state information obtained based on the measurement of the first and second sounding signals from a receiving end; wherein the channel state information comprises one or more of the following information: beam width information, adaptively quantized channel direction information, predicted channel quality information.
Preferably, there is a difference relationship between the beamforming coefficient of the first detection signal and the beamforming coefficient of the second detection signal, a first half of the beamforming coefficient of the second detection signal is the same as a first half of the beamforming coefficient of the first detection signal, and a second half of the beamforming coefficient of the second detection signal is an inverse number of the second half of the beamforming coefficient of the first detection signal.
Preferably, the beamforming coefficients of the first sounding reference signal are:
the beamforming coefficients of the second detection signal are:
wherein, thetaprobSending center angles of a first detection signal and a second detection signal, N is the number of antennas of a sending end, d is the distance between the antennas, and lambda is the wavelength;
the beamforming coefficient w1 of the first probe signal is an N-dimensional vector, the nth element of which is
Wherein N is more than or equal to 1 and less than or equal to N;
the beamforming coefficient w2 of the second sounding signal is an N-dimensional vector, the first N/2 elements of the N-dimensional vector are the same as the first N/2 elements of the beamforming coefficient of the first sounding signal, and the last N/2 elements are the inverses of the last N/2 elements of the beamforming coefficient of the first sounding signal (negating the signs of the corresponding elements).
Preferably, the beamwidth information is one or more beamform width combinations that can be obtained by the transmitting end by using different antenna weights.
Preferably, the method further comprises: the transmitting end adjusts the antenna weight so that the width of the transmission beam is equal to the beam width indicated by the beam width information.
Preferably, the adaptively quantized channel direction information includes quantization precision and channel direction information based on the quantization precision.
Preferably, the method further comprises: and the transmitting terminal extracts the channel direction information according to the quantization precision in the self-adaptive quantized channel direction information and aligns the beamforming center direction to the extracted channel direction.
Preferably, the predicted channel quality information is a modulation and coding scheme that the transmitting end should use after adjusting the beamforming scheme.
Preferably, the method further comprises: and the transmitting terminal transmits data according to the modulation coding mode.
The present application further provides a base station, including: signal transmission module and feedback receiving module, wherein:
a signal sending module, configured to send a first probe signal and a second probe signal in at least one probe interval;
a feedback receiving module, configured to receive, from a receiving end, channel state information obtained based on measurements on the first sounding signal and the second sounding signal; wherein the channel state information comprises one or more of the following information: beam width information, adaptively quantized channel direction information, predicted channel quality information.
The application also provides a channel state information feedback method, which comprises the following steps:
a receiving end receives a first detection signal and a second detection signal in at least one detection interval;
obtaining channel state information based on the first detection signal and the second detection signal, and feeding back the channel state information to a transmitting terminal; wherein the channel state information comprises one or more of the following information: beam width information, adaptively quantized channel direction information, predicted channel quality information.
Preferably, there is a difference relationship between the beamforming coefficient of the first detection signal and the beamforming coefficient of the second detection signal, the first half of the beamforming coefficient of the second detection signal is the same as the first half of the beamforming coefficient of the first detection signal, and the second half of the beamforming coefficient of the second detection signal has a sign that is the opposite of the second half of the beamforming coefficient of the first detection signal.
Preferably, the method further comprises: and the receiving terminal obtains the moving angular velocity of the receiving terminal by measuring the first detection signal and the second detection signal, and calculates the beam width information according to the channel quality and the moving angular velocity.
Preferably, the method further comprises: and the receiving end selects different quantization precisions according to the SNR and the moving angular velocity of the reference signal, and quantizes according to the selected quantization precision to obtain the channel direction information.
Preferably, the method further comprises: and after the transmitting end predicts the adjustment of the beamforming coefficient by the channel direction information and/or the beam width information fed back by the receiving end, the modulation and coding mode which should be used by the transmitting end is used as the predicted channel quality information.
Preferably, the prediction is derived by measuring the first detection signal and the second detection signal.
The present application further provides a terminal, including: signal reception module and feedback module, wherein:
the signal receiving module is used for receiving a first detection signal and a second detection signal in at least one detection interval;
the feedback module is used for obtaining channel state information based on the first detection signal and the second detection signal and feeding back the channel state information to a transmitting end; wherein the channel state information comprises one or more of the following information: beam width information, adaptively quantized channel direction information, predicted channel quality information.
According to the technical scheme, the transmitting end sends the first detection signal and the second detection signal in at least one detection interval, so that the receiving end can obtain channel state information such as beam width information, self-adaptive quantized channel direction information, predicted channel quality information and the like through detection of the first detection signal and the second detection signal, and after the channel state information is fed back to the transmitting end, the transmitting end can adjust the sending direction of beam forming, the beam width of beam forming and a modulation coding mode according to the channel state information, signaling overhead for feedback is reduced, and the base station is prevented from obtaining invalid channel state information.
Drawings
Fig. 1 is a schematic flowchart of a preferred acquisition method of channel state information based on a sounding reference signal at a transmitting end according to the present application;
fig. 2 is a schematic flow chart of a preferred feedback method for channel state information based on sounding reference signals at a receiving end according to the present application;
FIG. 3 is a schematic diagram illustrating the response of the first and second detection signals in different directions according to an embodiment of the present application;
FIG. 4 is a schematic diagram illustrating detection of channel direction errors based on a differential method according to an embodiment of the present application;
FIG. 5 is a schematic diagram of beam width indication feedback and beam adjustment according to an embodiment of the present invention;
fig. 6 is a schematic flow chart of terminal CQI prediction in the embodiment of the present application;
fig. 7 is a schematic diagram illustrating a method for calculating a predicted CQI of a terminal in an embodiment of the present application;
fig. 8 is a schematic diagram of a preferred base station of the present application;
fig. 9 is a schematic diagram of a preferred terminal structure according to the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below by referring to the accompanying drawings and examples.
The invention provides a method for acquiring channel state information, which can improve the feedback efficiency of the channel state information, reduce the feedback overhead and improve the efficiency of beam forming transmission based on feedback. The invention can be applied to a large-scale array antenna system under the traditional frequency band and can also be applied to a large-scale array antenna system based on millimeter waves.
Fig. 1 is a flowchart of a preferred acquisition method of channel state information based on sounding reference signal at a transmitting end, which illustrates main operations at a base station side, and includes:
step 1: the transmitting end transmits a first detection signal and a second detection signal in at least one detection interval.
Step 2: the transmitting end receives channel state information fed back by the terminal, wherein the channel state information is obtained based on the measurement of the first detection signal and the second detection signal, and the channel state information comprises one or more of the following information: channel direction information, adaptively quantized beamwidth information, and predicted channel quality information.
And step 3: and the transmitting end transmits data by using corresponding beam forming and modulation coding modes based on the channel state information. Specifically, the method comprises the following steps:
the beam width information is one or more of beam forming width combinations which can be obtained by the transmitting end by using different antenna weights, and the transmitting end adjusts the antenna weights so that the width of a transmitting beam is equal to the beam width indicated by the beam width information;
the self-adaptive quantized channel direction information comprises quantization precision and channel direction information based on the quantization precision, and the transmitting terminal extracts the channel direction information according to the quantization precision in the self-adaptive quantized channel direction information and aligns the beamforming center direction to the extracted channel direction;
the predicted channel quality information is a modulation coding mode which should be used after the transmitting end adjusts the beam forming mode, and the transmitting end transmits data according to the modulation coding mode.
After adjustment, the transmitting end transmits data by using the corresponding beam width, the beam forming center direction and the indicated modulation coding mode.
Fig. 2 is a flowchart of a preferred acquisition method of sounding-signal-based channel state information at a receiving end according to the present application, where the flowchart illustrates main operations at a terminal side, and includes:
step 1: the receiving end receives the first detection signal and the second detection signal in at least one detection interval.
Step 2: and estimating channel direction information according to the first detection signal and the second detection signal, and continuously monitoring the channel direction information to estimate the terminal moving angular velocity.
And step 3: and selecting the optimal beam width, the quantization precision of the channel direction information and the optimal modulation and coding mode.
And 4, step 4: feeding back channel state information to a transmitting end, wherein the channel state information comprises one or more of the following information: beam width information, adaptively quantized channel direction information, predicted channel quality information.
Detailed description of the preferred embodiment
The method for transmitting beam forming of the CDI sounding signal is explained in detail below with reference to fig. 3 and 4.
The beam forming method used by the base station for sending the first detection signal and the second detection signal is as follows: different precoding methods are used on different antennas, so that a difference relationship exists between the beamforming coefficient of the first detection signal and the beamforming coefficient of the second detection signal, the first half of the beamforming coefficient of the second detection signal is the same as the first half of the beamforming coefficient of the first detection signal, and the second half of the beamforming coefficient of the second detection signal is the opposite of the second half of the beamforming coefficient of the first detection signal. It should be noted that: the first and second sounding signals may themselves be the same signal on different time-frequency resources, differing by the beamforming coefficients. Specifically, the method comprises the following steps:
the beamforming coefficients (also referred to as beamforming weight coefficients) used for the first sounding signal are:
the beamforming coefficients used by the second sounding reference signal (the first sounding reference signal may also be referred to as a sounding reference signal, and correspondingly, the second sounding reference signal is referred to as an auxiliary sounding reference signal) are:
wherein, thetaprobThe transmission center angle of the first detection signal and the second detection signal is called a detection angle, N is the number of antennas at the transmitting end, d is the distance between the antennas, and λ is the wavelength. Namely: the beamforming coefficient w1 of the first probe signal is an N-dimensional vector whose nth element is expressed as
Wherein N is more than or equal to 1 and less than or equal to N; the beamforming coefficient w2 of the second sounding signal is an N-dimensional vector, the first N/2 elements of which are the same as the first N/2 elements of the beamforming coefficient of the first sounding signal, and the last N/2 elements of which are the inverses of the last N/2 elements of the beamforming coefficient of the first sounding signal (negating the signs of the corresponding elements).
Suppose the true channel direction of the terminal is θtrueThen the detection angle is deviated from the true channel direction of the terminal by Φ. As shown in fig. 3, the two probing signals will obtain different received signal gains at different offset values Φ. Thus, two groups of detection signals form one groupThe differential channel direction response enables the receiving end to perform differential calculation by using the differential information to obtain specific channel direction information thetatrue。
The receiving end carries out differential detection by calculating the gain ratio of the two groups of detection signals. As shown in fig. 4, when the deviation between the actual direction of the channel and the angle of the detection center is less than 0.2, there is a one-to-one correspondence relationship between the ratio of the two and the actual deviation: when the deviation is positive, the ratio of the auxiliary detection signal to the reception gain of the detection signal is real; when the deviation is negative, the ratio of the auxiliary detection signal to the receiving gain of the detection signal is an imaginary number; and as the absolute value of the deviation increases, the ratio of the reception gain also monotonically increases. Therefore, for different terminals located within (-0.2,0.2) angle relative to the probe center, the terminal can always estimate the deviation from the probe center angle by measuring the gain ratio of the two sets of probe signals.
In contrast, the conventional method can only compare the receiving gains of the terminal in multiple beam directions, and then select the beam direction with the highest gain. That is, the conventional method cannot obtain a resolution exceeding the beam width of the probe signal. The above-mentioned differential-based method can always obtain accurate channel direction information within the detection interval. This means that the differential method can achieve a measurement accuracy much higher than the conventional method.
Since the differential method can provide high-precision channel direction information measurement in the detection area, a new possibility is obtained for the receiving end: the angular velocity of the terminal is estimated by continuously measuring the channel direction information. Just as the terminal can estimate the velocity in the vertical direction with respect to the base station through the doppler shift, the terminal can obtain the angular velocity with respect to the base station by measuring the rate of change of the channel direction angle. One of the simplest methods is to measure the amount of change in the channel direction angle per unit time. For example, the terminal obtains the channel direction information according to two detection signals
And
calculating the terminal angular velocity:
since the angular velocity of the terminal determines the sensitivity of the terminal to the accuracy of the directional information: the higher the angular velocity, the higher the probability that the terminal is off the center of the beamforming direction. It is also known that the wider the beamforming, the less the variation in received power caused by the terminal being off-center from the beamforming. Therefore, the present application introduces a new channel state information indicator: a Beam Width Indication (BWI) is used to indicate Beam width information. The method comprises the following specific processes: a plurality of beam widths are predefined in the system, and the receiving end selects the optimal beam width by estimating the angular speed of the receiving end. The selection criteria for the beamwidth are: the terminal with the larger angular speed selects a wider wave beam to ensure the reliability of the link; the lower the angular velocity, the narrower the beam selected by the terminal to increase the received signal power. Fig. 5 is a schematic diagram of the beam width feedback and beam width adjustment. Meanwhile, the accuracy of the channel direction measurement can also be used as a reference criterion, and when a large error exists in the channel direction estimation, a wider beam is selected to ensure the reliability of the link.
Detailed description of the invention
Based on the method, the receiving end can measure accurate channel direction information. However, feeding back the quantized channel direction information to the base station must involve some overhead. Therefore, the quantization of the channel direction information needs to consider the balance between overhead and efficiency: higher quantization accuracy means that the base station can use more accurate beamforming, but must occupy higher uplink control signaling; conversely, a low quantization accuracy may effectively reduce the feedback overhead, but may reduce the beamforming efficiency of the base station. Therefore, an adaptive quantization accuracy selection can balance the relationship between the two, so that the overall performance of the system is improved. The system predefines a series of quantization precisions, from coarse to fine. The receiving end selects the optimal quantization precision according to the measured channel state. For example, if the SNR of the terminal is low or the moving speed of the terminal is high, the quantization accuracy is not high enough to effectively improve the beamforming efficiency. This is because the low SNR itself degrades the estimation of the channel direction information, and the high moving speed aggravates the timeliness of the channel information, and even if the fed back channel direction information is very accurate, the beamforming of the base station will deviate from the optimal direction. Therefore, the terminal can select the optimal quantization accuracy according to the measured SNR and the moving speed. One possible approach is to have quantization errors smaller than the errors introduced by the estimation error and the feedback delay. Meanwhile, the terminal should indicate the selected quantization precision in the feedback information. Since the angle of the detection space is fixed, the adaptive quantization accuracy selection can also effectively reduce unnecessary feedback overhead. Table 1 shows the multi-level quantization accuracy for a detection space of 0.4 pi.
TABLE 1
| Quantization levels | a | b | c |
| Number of |
2 | 3 | 4 |
| Quantization error | 0.1π | 0.05π | 0.025π |
| Matching SNR | 5dB | 10dB | 20dB |
Detailed description of the preferred embodiment
Channel Quality Information (CQI) is also an important indicator in the Channel state information, and the CQI indicates an optimal modulation and coding scheme that can be used by the base station. In the large-scale antenna system, the beam forming technology can effectively improve the SNR of the received signal. The base station may perform beamforming adjustment according to the fed back channel state information: including adjustment of direction and adjustment of beam width. These adjustments will affect the CQI measurements for the terminal. For example, when the beamforming can be more accurately aligned to the terminal, the terminal may use a higher order modulation scheme or a higher code rate coding due to a higher SNR. Due to the adoption of the high-precision channel direction information acquisition method, the terminal can accurately know the deviation between the channel direction and the current beam forming center angle. This provides a new possibility: the terminal can predict the SNR value obtained after the beam adjustment, that is, the optimal modulation and coding scheme after the beam adjustment, according to the deviation. The terminal can feed this predicted CQI back to the base station by feedback without measuring the CQI again after beam adjustment. Note that such a predicted beam-adjusted CQI is only possible if the high-precision channel direction information is known. Therefore, the conventional channel direction information acquisition method cannot support the novel feedback mode.
Fig. 6 is a flowchart of a method for feeding back a predicted CQI in an embodiment of the present application. First, the terminal receives the first sounding signal and the second sounding signal, and then estimates channel direction information and a received signal SNR. Then, the terminal calculates the change in the received signal power after the beamforming adjustment by the beamforming method on the base station side. Based on the calculation result, the terminal can predict the SNR value after beam adjustment, thereby obtaining the optimal CQI parameter. And finally, the terminal feeds back the predicted CQI parameters to the base station.
Fig. 7 is a specific example of a terminal predicting CQI in the embodiment of the present application. The terminal detects that the difference between the channel direction and the current beam forming center angle is 0.4 pi through the detection signal, and the current channel gain is 5. Based on the deviation, the terminal can obtain that the channel gain after the beamforming angle adjustment should be 10. Therefore, the SNR gain after beam adjustment is 2 times. And the terminal calculates the optimal CQI and feeds back the optimal CQI according to the information in sequence.
Corresponding to the above method, the present application further provides a base station, whose constituent structure is shown in fig. 8, and the base station includes: signal transmission module and feedback receiving module, wherein:
a signal sending module, configured to send a first probe signal and a second probe signal in at least one probe interval;
a feedback receiving module, configured to receive, from a receiving end, channel state information obtained based on measurements on the first sounding signal and the second sounding signal; wherein the channel state information comprises one or more of the following information: channel width information, adaptively quantized channel direction information, predicted channel quality information.
Preferably, the beamforming coefficient of the first sounding signal and the beamforming coefficient of the second sounding signal sent by the signal sending module have a differential relationship, a first half of the beamforming coefficient of the second sounding signal is the same as a first half of the beamforming coefficient of the first sounding signal, and a second half of the beamforming coefficient of the second sounding signal is an inverse number of the second half of the beamforming coefficient of the first sounding signal.
Preferably, the beamforming coefficients of the first sounding reference signal are:
the beamforming coefficients of the second detection signal are:
wherein, thetaprobThe sending center angle of the first detection signal and the second detection signal is shown, N is the number of antennas at the sending end, d is the distance between the antennas, and lambda is the wavelength. That is, the beamforming coefficient of the first detection signal is an N-dimensional vector, and the nth element is expressed as
Wherein N is more than or equal to 1 and less than or equal to N; the beamforming coefficient of the second detection signal is an N-dimensional vector, the first N/2 elements of the N-dimensional vector are the same as the first N/2 elements of the beamforming coefficient of the first detection signal, and the last N/2 elements of the N-dimensional vector are the opposite numbers of the last N/2 elements of the beamforming coefficient of the first detection signal (the signs of the corresponding elements are inverted).
Preferably, the beam width information received by the feedback receiving module is one or more of beam forming width combinations that can be obtained by using different antenna weights at a transmitting end;
the signal sending module is further configured to adjust the antenna weights so that the width of the sending beam is equal to the beam width indicated by the beam width information.
Preferably, the adaptively quantized channel direction information received by the feedback receiving module includes quantization precision and channel direction information based on the quantization precision;
preferably, the predicted channel quality information received by the feedback receiving module is a modulation and coding scheme that should be used after the transmitting end adjusts the beamforming scheme;
the signal sending module is further configured to send data according to the modulation and coding scheme.
Corresponding to the above method, the present application further provides a terminal, a composition structure of which is shown in fig. 9, including: signal reception module and feedback module, wherein:
the signal receiving module is used for receiving a first detection signal and a second detection signal in at least one detection interval;
the feedback module is used for obtaining channel state information based on the first detection signal and the second detection signal and feeding back the channel state information to a transmitting end; wherein the channel state information comprises one or more of the following information: channel width information, adaptively quantized channel direction information, predicted channel quality information.
Preferably, there is a difference relationship between the beamforming coefficient of the first detection signal and the beamforming coefficient of the second detection signal, a first half of the beamforming coefficient of the second detection signal is the same as a first half of the beamforming coefficient of the first detection signal, and a second half of the beamforming coefficient of the second detection signal is an inverse number of the second half of the beamforming coefficient of the first detection signal.
Preferably, the feedback module is configured to obtain a moving angular velocity of the receiving end by measuring the first probe signal and the second probe signal, and calculate the beam width information according to the channel quality and the moving angular velocity.
Preferably, the feedback module is configured to select different quantization accuracies according to the SNR of the reference signal and the moving angular velocity, and quantize according to the selected quantization accuracy to obtain the channel direction information.
Preferably, the feedback module is configured to predict a modulation and coding scheme that the transmitting end should use after adjusting the beamforming coefficient according to the channel direction information and/or the beam width information fed back by the transmitting end based on the receiving end, and use the modulation and coding scheme as the predicted channel quality information.
Preferably, the feedback module performs the prediction by measuring the first detection signal and the second detection signal.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the scope of protection of the present application.
Claims (26)
1. A method for acquiring channel state information is characterized by comprising the following steps:
a transmitting terminal transmits a first detection signal and a second detection signal in at least one detection interval; a difference relationship exists between the beamforming coefficient of the first detection signal and the beamforming coefficient of the second detection signal, wherein the first half of the beamforming coefficient of the second detection signal is the same as the first half of the beamforming coefficient of the first detection signal, and the second half of the beamforming coefficient of the second detection signal is the opposite number of the second half of the beamforming coefficient of the first detection signal;
receiving channel state information obtained based on the measurement of the first and second sounding signals from a receiving end; wherein the channel state information comprises one or more of the following information: beam width information, adaptively quantized channel direction information, predicted channel quality information.
2. The method of claim 1, wherein: the beamforming coefficient of the first detection signal is:
the beamforming coefficients of the second detection signal are:
wherein, thetaprobSending center angles of a first detection signal and a second detection signal, N is the number of antennas of a sending end, d is the distance between the antennas, and lambda is the wavelength;
the beamforming coefficient w1 of the first probe signal is an N-dimensional vector, the nth element of which is
Wherein N is more than or equal to 1 and less than or equal to N;
the beamforming coefficient w2 of the second sounding signal is an N-dimensional vector, the first N/2 elements of the N-dimensional vector are the same as the first N/2 elements of the beamforming coefficient of the first sounding signal, and the last N/2 elements are the opposite numbers of the symbols of the last N/2 elements of the beamforming coefficient of the first sounding signal.
3. The method according to any one of claims 1 to 2, characterized in that:
the beam width information is one or more of beam forming width combinations which can be obtained by the transmitting end by using different antenna weights.
4. The method of claim 3, wherein:
the method further comprises the following steps: the transmitting end adjusts the antenna weight so that the width of the transmission beam is equal to the beam width indicated by the beam width information.
5. The method according to any one of claims 1 to 2, characterized in that:
the adaptively quantized channel direction information includes a quantization precision and channel direction information based on the quantization precision.
6. The method of claim 5, wherein:
the method further comprises the following steps: and the transmitting terminal extracts the channel direction information according to the quantization precision in the self-adaptive quantized channel direction information and aligns the beamforming center direction to the extracted channel direction.
7. The method according to any one of claims 1 to 2, characterized in that:
the predicted channel quality information is a modulation coding mode which should be used after the transmitting end adjusts the beam forming mode.
8. The method of claim 7, wherein:
the method further comprises the following steps: and the transmitting terminal transmits data according to the modulation coding mode.
9. A base station, comprising: signal transmission module and feedback receiving module, wherein:
a signal sending module, configured to send a first probe signal and a second probe signal in at least one probe interval; a difference relationship exists between the beamforming coefficient of the first detection signal and the beamforming coefficient of the second detection signal, wherein the first half of the beamforming coefficient of the second detection signal is the same as the first half of the beamforming coefficient of the first detection signal, and the second half of the beamforming coefficient of the second detection signal is the opposite number of the second half of the beamforming coefficient of the first detection signal
A feedback receiving module, configured to receive, from a receiving end, channel state information obtained based on measurements on the first sounding signal and the second sounding signal; wherein the channel state information comprises one or more of the following information: beam width information, adaptively quantized channel direction information, predicted channel quality information.
10. The base station of claim 9, wherein:
the beamforming coefficient of the first detection signal is:
the beamforming coefficients of the second detection signal are:
wherein, thetaprobSending center angles of a first detection signal and a second detection signal, N is the number of antennas of a sending end, d is the distance between the antennas, and lambda is the wavelength;
the beamforming coefficient w1 of the first probe signal is an N-dimensional vector, the nth element of which is
Wherein N is more than or equal to 1 and less than or equal to N;
the beamforming coefficient w2 of the second sounding signal is an N-dimensional vector, the first N/2 elements of the N-dimensional vector are the same as the first N/2 elements of the beamforming coefficient of the first sounding signal, and the last N/2 elements are the opposite numbers of the symbols of the last N/2 elements of the beamforming coefficient of the first sounding signal.
11. The base station according to any of claims 9 to 10, characterized by:
the beam width information is one or more of beam forming width combinations which can be obtained by the transmitting end by using different antenna weights.
12. The base station of claim 11, wherein:
the signal transmission module further includes: the transmitting end adjusts the antenna weight so that the width of the transmission beam is equal to the beam width indicated by the beam width information.
13. The base station according to any of claims 9 to 10, characterized by:
the adaptively quantized channel direction information includes a quantization precision and channel direction information based on the quantization precision.
14. The base station of claim 13, wherein:
the signal transmission module further includes: and the transmitting terminal extracts the channel direction information according to the quantization precision in the self-adaptive quantized channel direction information and aligns the beamforming center direction to the extracted channel direction.
15. The base station according to any of claims 9 to 10, characterized by:
the predicted channel quality information is a modulation coding mode which should be used after the transmitting end adjusts the beam forming mode.
16. The base station of claim 15, wherein:
the signal transmission module further includes: and the transmitting terminal transmits data according to the modulation coding mode.
17. A method for feeding back channel state information, comprising:
a receiving end receives a first detection signal and a second detection signal in at least one detection interval; a difference relationship exists between the beamforming coefficient of the first detection signal and the beamforming coefficient of the second detection signal, wherein the difference relationship exists between the beamforming coefficient of the first detection signal and the beamforming coefficient of the second detection signal, the first half of the beamforming coefficient of the second detection signal is the same as the first half of the beamforming coefficient of the first detection signal, and the second half of the beamforming coefficient of the second detection signal is the opposite of the second half of the beamforming coefficient of the first detection signal;
detecting based on the first detection signal and the second detection signal to obtain channel state information, and feeding back the channel state information to a transmitting terminal; wherein the channel state information comprises one or more of the following information: beam width information, adaptively quantized channel direction information, predicted channel quality information.
18. The method of claim 17, wherein:
the method further comprises the following steps: and the receiving terminal obtains the moving angular velocity of the receiving terminal by measuring the first detection signal and the second detection signal, and calculates the beam width information according to the channel quality and the moving angular velocity.
19. The method according to claim 17 or 18, characterized in that:
the method further comprises the following steps: and the receiving end selects different quantization precisions according to the SNR and the moving angular velocity of the reference signal, and quantizes according to the selected quantization precision to obtain the channel direction information.
20. The method according to claim 17 or 18, characterized in that:
the method further comprises the following steps: and after the transmitting end predicts the adjustment of the beamforming coefficient by the channel direction information and/or the beam width information fed back by the receiving end, the modulation and coding mode which should be used by the transmitting end is used as the predicted channel quality information.
21. The method of claim 20, wherein:
the prediction is derived by measuring the first detection signal and the second detection signal.
22. A terminal, comprising: signal reception module and feedback module, wherein:
the signal receiving module is used for receiving a first detection signal and a second detection signal in at least one detection interval; a difference relationship exists between the beamforming coefficient of the first detection signal and the beamforming coefficient of the second detection signal, wherein the difference relationship exists between the beamforming coefficient of the first detection signal and the beamforming coefficient of the second detection signal, the first half of the beamforming coefficient of the second detection signal is the same as the first half of the beamforming coefficient of the first detection signal, and the second half of the beamforming coefficient of the second detection signal is the opposite of the second half of the beamforming coefficient of the first detection signal;
the feedback module is used for obtaining channel state information based on the first detection signal and the second detection signal and feeding back the channel state information to a transmitting end; wherein the channel state information comprises one or more of the following information: beam width information, adaptively quantized channel direction information, predicted channel quality information.
23. The terminal of claim 22, wherein:
the feedback module further comprises: and the receiving terminal obtains the moving angular velocity of the receiving terminal by measuring the first detection signal and the second detection signal, and calculates the beam width information according to the channel quality and the moving angular velocity.
24. A terminal according to claim 22 or 23, characterized in that:
the feedback module further comprises: and the receiving end selects different quantization precisions according to the SNR and the moving angular velocity of the reference signal, and quantizes according to the selected quantization precision to obtain the channel direction information.
25. A terminal according to claim 22 or 23, characterized in that:
the feedback module further comprises: and after the transmitting end predicts the adjustment of the beamforming coefficient by the channel direction information and/or the beam width information fed back by the receiving end, the modulation and coding mode which should be used by the transmitting end is used as the predicted channel quality information.
26. The terminal of claim 25, wherein:
the prediction is derived by measuring the first detection signal and the second detection signal.
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| PCT/KR2016/008414 WO2017023054A1 (en) | 2015-07-31 | 2016-07-29 | Methods for acquiring and feeding back channel state information, base station and terminal |
| US15/224,610 US10425855B2 (en) | 2015-07-31 | 2016-07-31 | Methods for acquiring and feeding back channel state information, base station and terminal |
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| CN112368968B (en) * | 2018-07-10 | 2022-04-29 | 华为技术有限公司 | Method and device for reporting channel state information |
| US10979122B2 (en) * | 2019-03-21 | 2021-04-13 | Samsung Electronics Co., Ltd. | Wireless communication apparatus for adaptive beamforming and method of operation thereof |
| CN111106861B (en) * | 2019-12-06 | 2021-07-23 | 南方科技大学 | Method for beamforming by angular velocity prediction of mmWave channel distribution |
| CN115053498B (en) * | 2020-02-21 | 2024-05-14 | 华为技术有限公司 | Method and device for predicting channel state information |
| CN111786706B (en) * | 2020-07-02 | 2022-03-08 | 电子科技大学 | Joint channel information acquisition and beam forming method |
| CN114520713B (en) * | 2020-11-20 | 2024-03-01 | 上海华为技术有限公司 | Channel detection period configuration method, base station, equipment and medium |
| CN115278718A (en) * | 2021-04-30 | 2022-11-01 | 华为技术有限公司 | Method and device for obtaining channel information |
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| US9178583B2 (en) * | 2013-01-08 | 2015-11-03 | Samsung Electronics Co., Ltd. | Channel state information feedback design in advanced wireless communication systems |
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