CN116488742A - Channel correction method based on terminal assistance - Google Patents

Channel correction method based on terminal assistance Download PDF

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Publication number
CN116488742A
CN116488742A CN202210956772.7A CN202210956772A CN116488742A CN 116488742 A CN116488742 A CN 116488742A CN 202210956772 A CN202210956772 A CN 202210956772A CN 116488742 A CN116488742 A CN 116488742A
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China
Prior art keywords
channel
feedback
correction
correction method
information
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CN202210956772.7A
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Inventor
李彪
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Shenzhen Itest Technology Co ltd
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Shenzhen Itest Technology Co ltd
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Priority to CN202210956772.7A priority Critical patent/CN116488742A/en
Publication of CN116488742A publication Critical patent/CN116488742A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/10—Monitoring; Testing of transmitters
    • H04B17/11—Monitoring; Testing of transmitters for calibration
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Power Engineering (AREA)
  • Radio Transmission System (AREA)

Abstract

The invention provides a channel correction method based on terminal assistance, which comprises the following steps: step1: the transmitting end selects required equipment from N receiving end equipment as a correction auxiliary target terminal based on channel information fed back by the receiving end; step2: the sender informs the target terminal of periodically feeding back the channel information of the appointed port based on the control word MAC CE. Step3, the terminal carries out channel estimation on the appointed port based on the received control word MAC CE and feeds back the relevant channel information to the transmitting end; step4, the transmitting end calculates a correction coefficient by fitting based on the uplink channel information on the received uplink signal and the downlink channel information contained in the feedback information of the receiving end. The beneficial effects of the invention are as follows: the channel correction method of the invention gives up the traditional high-cost scheme based on the auxiliary hardware channel, and can realize low-cost high-reliability reciprocity correction based on the antenna selection and the channel feedback of the receiving terminal.

Description

Channel correction method based on terminal assistance
Technical Field
The invention relates to the technical field of TDD wireless communication MIMO, in particular to a channel correction method based on terminal assistance.
Background
In order to reduce the feedback cost of channel information in TDD communication, the method uses uplink channel information to reversely push the related information of a downlink channel based on the reciprocity characteristic of an air interface channel so as to obtain a MIMO precoding matrix; and the channel reciprocity comprises the reciprocity of the air interface and the reciprocity of the signal transmission characteristics of the radio frequency device, and the channel correction technology is used for guaranteeing the reciprocity of the radio frequency receiving and transmitting channel at the transmitting side.
In a TDD system, if the time interval between uplink and downlink transmissions is smaller than the coherence time, the signal experiences the same fading in uplink transmission and downlink transmission according to the transmission characteristics of electromagnetic waves, so that the base station can obtain uplink channel state information as a reference for downlink channel precoding according to channel estimation. However, in practice, the wireless channel includes an air interface channel and a radio frequency channel, the time-frequency channel of TDD uses the same hardware link, and the transceiving state of the channel is controlled by selectively switching, as shown in fig. 1, the receiving channel characteristic and the transmitting channel characteristic of the link are different in gain and time delay, and the channel reciprocity is no longer established due to the mismatch of the radio frequency receiving and transmitting channels.
At this time, in order to perform downlink precoding using uplink channel state information, it is necessary to correct the inconsistency of the transceiving radio frequency channels to be consistent, i.e., to correct reciprocity. As shown in fig. 2: a communication link typically includes two parts, a baseband and a medium radio frequency, where the baseband processes the signal based on digital signal, and the different channels have no significant differential effect on the amplitude and phase of the modulated signal transmitted over the air. And the signal which is transmitted by the modulated signal comprises a transmitting side radio frequency channel, an air interface transmission channel and a receiving side radio frequency channel. The TDD air interface channel is based on the principle that the electromagnetic wave transmission path is reversible, because TDD uses the same frequency point, and the transceiving time interval is very short, so that reciprocity on the air interface is naturally established in the coherent time range, the reciprocity on the receiving side has little influence on the communication performance of the system, and the consistency correction is not needed in general, so that the channel correction is called as transceiving reciprocity correction of the transmitting side radio frequency channel.
The transmit link may be expressed as:
the receive link may be expressed as:
the goal of channel reciprocity correction is to hold the following relationship: the ratio of the transmitting channel to the receiving channel at the transmitting side is constant:
in an N-channel MIMO system, in order to obtain stable beamforming gain, all channel transmit/receive ratio values are required to be the same constant.
The current channel correction stage is implemented in two ways, one is display correction represented by 3GPP and the other is implicit correction represented by WLAN, and reference can be made to the following documents:
CN 201210578470-channel correction device, method and system
CN 201210543992-channel correction method, device and wireless access system
Method for correcting channel between CN201310733735 and base station
CN 201480077354-channel correction device and method
CN 201810242062-radio frequency channel correction method and device
3GPP correction scheme
Most manufacturers currently use an Argos correction scheme, that is, based on the added auxiliary correction rf channel and coupler, a signal loop is generated between different channels, so as to obtain the relationship between the characteristics of the communication transceiver channel, as shown in fig. 3.
Wherein, the channel A and the channel B are signal channels needed by normal communication, and the channel C is an auxiliary correction channel additionally added for completing the receiving and transmitting reciprocity of the channel A and the channel B. The channel correction process is completed in the following steps:
step1: channel C sends signals, and at the antenna exit, the signals are coupled back to channel a and channel B via a coupler, where channels a, B are in a signal receiving state, and a channel state can be obtained:
H CA ＝H TXC *H RXA
H CB ＝H TXC *H RXB
step2, the channel A sends a signal, and enters a receiving channel of the channel C through a coupler to obtain a channel state:
H AC ＝H TXA *H RXC
step3, the channel B sends a signal, and enters a receiving channel of the channel C through a coupler to obtain a channel state:
H BC ＝H TXB *H RXC
step4, the baseband acquires all the channel information to obtain the receiving and transmitting correction coefficients of the channel A and the channel B:
wherein, the liquid crystal display device comprises a liquid crystal display device,is of the same amount, so that only the +.>And->As a result, the two are equal to each other, thereby achieving the purpose of correction; and these are all known quantities obtained from channel estimation.
Wherein A is an amplitude correction factor,is phase ofCorrection factors.
802.11 correction scheme
When the 802.11 standard is implemented, a calibration idea based on channel feedback information is proposed, as shown in fig. 4. The MIMO system with M antennas at the transmitting side and N antennas at the receiving side is characterized in that the receiving side measures and obtains a channel matrix with M-N dimensions, and feeds back the complete channel matrix to the transmitting side for channel reciprocity correction at the transmitting side, but the final system is not applied because of overlarge feedback overhead of an H matrix.
Disadvantages of the prior art:
the biggest shortcoming of the Argos technology is that an auxiliary radio frequency link and a large number of couplers are needed, the correction needs complex timing relation processing, the correction needs extra time-frequency resource expenditure, and the implementation cost is very high. The technical scheme of 802.11 causes great channel capacity overhead due to huge feedback data volume of the MIMO channel; when the data volume is large due to the contention-based access mode of the 802.11 system, the channel feedback delay is large, and the correction effect is poor; in addition, many MIMO products adopt an asymmetric radio frequency transceiving technology, and the number of receiving channels is often greater than the number of transmitting channels, so that in the channel matrix with m×n dimensions, ambiguity exists in the matching of the uplink channel port and the downlink channel port, which leads to correction failure, and finally, the scheme is not practically applied.
Disclosure of Invention
The invention provides a channel correction method based on terminal assistance, which comprises the following steps:
step1: the transmitting end selects a required device from N receiving end devices as a correction auxiliary target terminal based on the channel information fed back by the receiving end.
Step2: the sender informs the target terminal of periodically feeding back the channel information of the appointed port based on the control word MAC CE.
Step3, the terminal carries out channel estimation on the appointed port based on the received control word MAC CE and feeds back the relevant channel information to the transmitting end.
Step4, the transmitting end calculates a correction coefficient by fitting based on the uplink channel information on the received uplink signal and the downlink channel information contained in the feedback information of the receiving end.
As a further improvement of the present invention, in Step2, the control word MAC CE indicates the fed back UE, the feedback period, and the feedback port information.
As a further improvement of the present invention, in Step2, a bidirectional MAC CE control word is set, and the forward control word instructs the receiving end to perform channel feedback, where the port of the feedback channel, the frequency domain granularity and the time domain period, and the reverse control word feeds back specific channel data.
As a further improvement of the present invention, in Step2, based on the number of transmission ports and transmission capability of the feedback-side device, data of one port or data of a plurality of ports is selected to be fed back.
As a further improvement of the present invention, in Step2, the channel ports and the ports of the feedback side are in one-to-one correspondence when the transmitting side acquires the uplink channel.
As a further improvement of the invention, in Step2, the channel can be fed back together by a plurality of feedback devices.
As a further improvement of the present invention, in Step4, the following formula is also included:
H UL ＝H TXUE0 *H air *H RXeNB 。
as a further improvement of the present invention, in Step4, for each channel of the originating endBased on the corresponding uplink and downlink channels->The relation between the receiving and transmitting can be obtained, and for a wide system, the amplitude and phase correction factors of the channel can be fitted based on subcarrier information.
The beneficial effects of the invention are as follows: the channel correction method of the invention gives up the traditional high-cost scheme based on the auxiliary hardware channel, and can realize low-cost high-reliability reciprocity correction based on the antenna selection and the channel feedback of the receiving terminal.
Drawings
FIG. 1 is a background diagram of the invention;
FIG. 2 is a diagram of the uplink and downlink channel composition according to the background of the invention;
FIG. 3 is a diagram of the background of the invention-a calibration schematic based on auxiliary RF channels;
fig. 4 is a schematic diagram of feedback channel information for a receiving node according to the background of the invention;
FIG. 5 is a schematic diagram of a correction UE selection in accordance with the present invention;
fig. 6 is a schematic diagram of feedback of downlink channel information from the UE side back to the base station according to the present invention;
FIG. 7 is a schematic diagram of a base station estimating uplink channel information according to the present invention;
fig. 8 is a schematic diagram of signal transmission on the transmitting side and the receiving side of the present invention;
fig. 9 is a schematic diagram of an ENB controlling feedback channel information of a plurality of terminals through a MAC CE according to the present invention.
Detailed Description
As embodiment 1 of the present invention, the channel correction method based on terminal assistance disclosed in the present invention selects a quasi-stationary terminal as a channel information feedback terminal based on Doppler (Doppler frequency offset) frequency offset information of a terminal channel. The selected terminal selectively feeds back the receiving channel information corresponding to the own transmitting antenna to the transmitting side, and the transmitting side determines the correction coefficient based on a fitting algorithm. The channel correction method of the invention comprises the following implementation steps:
step1: the transmitting end (e.g., base station side) selects a device with better channel quality and lower Doppler frequency from the N receiving end devices as a correction auxiliary target terminal based on the channel information fed back by the receiving end (e.g., UE side), as shown in fig. 5.
Step2, the sender (e.g. base station side) informs the target terminal to periodically feed back the channel information of the designated port based on a control word MAC CE (Medium Access Control Control Element media access control layer control word), wherein the control word MAC CE indicates fed back UE, a feedback period and feedback port information.
Step3, the terminal carries out channel estimation on the appointed port based on the received control word MAC CE and feeds back the relevant channel information to the base station. As shown in fig. 6, the UE side has multiple receiving ports, and based on the channel information of Port0 indicated by the base station, the UE (User Equipment) performs channel estimation based on the received signal of Port0, and feeds back the channel information to the base station, where the channel information is fed back to the transmitting antenna Port of the UE in Port 0.
The formula is as follows:
wherein H is DL Representing downlink channel information; h UL Representing uplink channel information; h air Representing air interface channel information; h TxeNB Representing the equivalent channel information of the radio frequency link transmitted by the eNB node; h RXUE0 Equivalent channel information indicating UE reception channel 0; h TXUE0 Equivalent channel information indicating UE transmit lane 0; h RXeNB Indicating that the eNB node receives radio frequency link equivalent channel information.
Step4, the base station calculates the correction coefficient by fitting based on the uplink channel information on the received uplink signal, as shown in fig. 7, and the downlink channel information included in the UE feedback information.
The formula is as follows:
H UL ＝HT XUE0 *H air *H RXeNB
because the air interface link is theoretically reciprocal, the UE uses the same port for receiving and transmitting, so the proportion of the receiving and transmitting characteristics of the UE is constantThe following relationship holds:
the ratio of the receiving and transmitting channel characteristics of the transmitting side radio frequency channel is the ratio of the channel characteristics of the uplink and downlink systems. For each channel of the originating terminalBased on the corresponding uplink and downlink channels->The relation between the receiving and transmitting can be obtained, and for a wide system, a plurality of subcarrier information is available, and the amplitude and phase correction factors of the channel can be fitted based on the information, so that the estimation accuracy is improved.
Currently, most modern communication systems such as LTE base stations, 5G base stations, WLAN products, phased array radars and the like all adopt beamforming technology to improve the transmission capability of the system. Along with the development of radio frequency technology, more and more terminal products also start to use a Beamforming stage, the number of various communication devices is very large, and if each product is reduced by one auxiliary correction radio frequency channel and a plurality of couplers, considerable social resources can be saved.
Based on the terminal-assisted correction scheme, the same correction effect of the Argos correction scheme can be obtained, but the Argos correction system is realized by adding an additional radio frequency channel and a coupler in the system, and the terminal-assisted correction scheme is used for skillfully realizing signal loop-back by using terminal feedback, and the function of responding to hardware in the Argos scheme can be replaced by software information feedback by means of the existing signal interaction flow of the communication system. The invention is completely established in theory, is easy to realize in engineering and has extremely high market value.
The Argos correction scheme relies on the reliability of the correction rf channel, and if the channel fails, the entire correction system will fail; the channel correction method disclosed by the invention can use any terminal in the network for assisting channel correction, and has very high system robustness.
As embodiment 2 of the present invention, embodiment 2 is a further improvement over embodiment 1:
most MIMO communication terminal apparatuses in the current market have a larger number of reception channels than transmission channels, as shown in fig. 8. In the antenna ports of the terminal, part of the ports are unidirectional receiving signals, part of the ports are shared by transmitting and receiving, and only part or all of the transmitting ports can be used when the terminal transmits data. The bidirectional MAC CE control word is set for the system, the forward control word commands the receiving end to execute channel feedback, the port of the feedback channel, the frequency domain granularity and the time domain period are fed back, and the reverse control word feeds back specific channel data. Based on the number of transmitting ports and transmitting capability of the feedback side device, data of one port or data of a plurality of ports can be selected to be fed back.
Assuming that k ports among the N receiving ports of the feedback side have transmission capability, the transmitting side (ENB) may control the feedback side (UE) to feed back channel information of one, several or all of the k ports as shown in the following formula.
It can be seen that only part of the information in the whole channel information matrix needs to be selected, so that the complexity of the system can be reduced.
Since the data for radio frequency channel correction is known to the transmitting side from that device, and those ports of the device, the channel data of any of the k ports is valid, and the only constraint is that the transmitting side, when acquiring the uplink channel, has to be in one-to-one correspondence with the ports of the feedback side, i.e. the feedback side feeds back the channel of Port0, the data used by the base station for uplink channel estimation must be the pilot data for channel estimation sent on the transmitting side Port 0.
As embodiment 3 of the present invention, embodiment 3 is a further improvement over embodiment 1:
to reduce the communication burden of a single channel feedback device, correction may be achieved by way of multi-device feedback. Because the information fed back by the feedback equipment is transparent to the radio frequency channel correction of the transmitting side equipment, namely the radio frequency channel characteristics of the feedback equipment do not influence the result of the channel correction of the transmitting side, the single feedback equipment feeds back the time-frequency low-density channel information, and the plurality of feedback equipment feed back the channels together, the transmitting side can be ensured to obtain enough data for correction, and the correction precision is ensured.
As shown in fig. 9, the ENB controls a plurality of terminals to feed back channel information through a control word MAC CE, but each terminal feeds back only the sampled channel vector data h 0k Standing at the terminalFrom the perspective of the end side, the correction requirement of the transmitting side can be met only by transmitting a small amount of data information, and no obvious feedback resource consumption is caused to the feedback side; from the perspective of the base station side, data can be obtained from a plurality of terminals in the network for channel correction, and the reliability and the robustness of correction can be ensured. In the Argos system, if the correction channel fails, the whole correction system cannot work normally.
The invention has the beneficial effects that: the channel correction method of the invention gives up the traditional high-cost scheme based on the auxiliary hardware channel, and can realize low-cost high-reliability reciprocity correction based on the antenna selection and the channel feedback of the receiving terminal.
The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.

Claims (8)

1. A terminal-assisted channel correction method, comprising the steps of: step1: the transmitting end selects required equipment from N receiving end equipment as a correction auxiliary target terminal based on channel information fed back by the receiving end;
step2: the transmitting end informs the target terminal of periodically feeding back the channel information of the appointed port based on the control word MAC CE;
step3: the terminal carries out channel estimation on the appointed port based on the received control word MAC CE, and feeds back relevant channel information to the transmitting end;
step4: the transmitting end fits and calculates a correction coefficient based on the uplink channel information on the received uplink signal and the downlink channel information contained in the feedback information of the receiving end.
2. The channel correction method according to claim 1, characterized in that in Step2, a control word MAC CE indicates fed back UE, a feedback period, feedback port information.
3. The channel correction method according to claim 2, wherein in Step2, a bidirectional MAC CE control word is set, and the forward control word instructs the receiving end to perform channel feedback, and the port of the feedback channel, the frequency domain granularity and the time domain period, and the reverse control word feeds back specific channel data.
4. The channel correction method according to claim 3, wherein in Step2, based on the number of transmission ports and transmission capability of the feedback-side device, data of one port or data of a plurality of ports is selected to be fed back.
5. The channel correction method according to claim 3, wherein in Step2, the channel ports and the ports of the feedback side are in one-to-one correspondence when the transmission side acquires the uplink channel.
6. A channel correction method according to claim 3, characterized in that in Step2, channels can be fed back together by a plurality of feedback devices.
7. The channel correction method according to claim 1, characterized in that in Step4, further comprising the following formula:
H UL ＝H TXUE0 *H air *H RXeNB 。
8. the lane correction method according to claim 7, wherein in Step4, for each lane of the originating terminalBased on the corresponding uplink and downlink channels->The relation between the receiving and transmitting can be obtained, and for a wide system, the fitting can be based on subcarrier informationAnd outputting amplitude and phase correction factors of the channels.
CN202210956772.7A 2022-08-10 2022-08-10 Channel correction method based on terminal assistance Pending CN116488742A (en)

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Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210956772.7A CN116488742A (en) 2022-08-10 2022-08-10 Channel correction method based on terminal assistance

Publications (1)

Publication Number Publication Date
CN116488742A true CN116488742A (en) 2023-07-25

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