CN101674655A - Method and system for acquiring information of uplink channel and downlink channel - Google Patents

Abstract

The present invention provides a downlink channel information acquisition method. The terminal sends the detection pilot and downlink interference information to the base station; the base station obtains the uplink channel state information according to the detection pilot, and then obtains the equivalent downlink channel state information; according to the equivalent downlink Channel state information and downlink interference information acquire downlink channel related information. Also provided is a downlink channel information acquisition system. A method for obtaining uplink channel information is also provided, including: the base station sends uplink interference information and downlink pilots to the terminal; the terminal acquires downlink channel state information according to the downlink pilots, and then obtains equivalent uplink channel state information; according to the equivalent uplink The channel state information and the uplink interference information obtain uplink channel related information, and send the obtained uplink channel quality information to the base station. The invention also provides an uplink channel information acquisition system. The present invention utilizes channel reciprocity to obtain channel information, reducing uplink overhead.

Description

A method and system for acquiring uplink and downlink channel information

technical field

The present invention relates to the field of digital communication, in particular to long-term evolution/advanced long-term evolution (Long Term Evolution/Long Term Evolution-Advanced, referred to as LTE/LTE-A) system in time division duplex (Time Division Duplex, referred to as TDD) mode uplink And a downlink channel information acquisition method and system.

Background technique

In the LTE/LTE_A system, in order to perform downlink scheduling and resource allocation, the base station needs to obtain relevant information about the downlink channel, which includes Pre-coded Matrix Indication (PMI for short), Channel Quality Information (Channel Quality Information for short) CQI) and rank indication information (Rank Indication, RI for short), etc. To this end, the base station sends a common reference symbol (Common Reference Symbol, CRS for short)/channel state information pilot signal (Channel State Information Reference Symbol, CSI-RS for short) to the terminal (User Equipment, referred to as UE) in the downlink, and the UE according to these The pilot measures the relevant information of the downlink channel, such as the above-mentioned PMI, CQI and RI, etc., and then feeds back the above information to the base station through the uplink control channel (Physical Uplink ControlChannel, referred to as PUCCH) or uplink shared channel (Physical Uplink Shared Channel, referred to as PUSCH) ,As shown in Figure 1.

Correspondingly, in order to perform uplink scheduling and resource allocation, the base station needs to obtain uplink channel related information, which includes Pre-coded Matrix Indication (PMI for short), Channel Quality Information (CQI for short) and rank Indication information (RankIndication, RI for short) and the like. To this end, a commonly used method is that the UE sends a Sounding Reference Symbol (SRS for short) to the base station, and the base station performs uplink channel measurement according to the SRS, obtains uplink channel related information, and sends uplink authorization information to the UE accordingly. The UE sends uplink service data according to the uplink authorization information, as shown in FIG. 2 .

One of the main problems of the acquisition method of downlink channel related information is that the uplink feedback overhead is relatively large, especially in LTE-A, for Co-ordinated Multi-Points (CoMP for short) transmission, in order to achieve optimal CoMP For operations such as preprocessing and selection of cooperative cells, the UE needs to feed back a large amount of channel-related information to the base station; in addition, because PMI, CQI and other information compress the downlink channel information to a certain extent, they cannot completely and accurately reflect the downlink channel information. In this way, operations such as downlink resource scheduling, precoding, and coordinated cell selection are affected to a certain extent, resulting in downlink transmission quality degradation.

For the acquisition method of uplink channel related information, since SRS usually occupies the last symbol of each subframe, the overhead is relatively large, and even if only one user among all users sends SRS, the last symbol in the subframe needs to be vacated. This will also cause a lot of waste of resources.

Contents of the invention

The technical problem to be solved by the present invention is to provide a downlink channel information acquisition method and system to reduce uplink feedback overhead.

In order to solve the above problems, the present invention provides a method for acquiring downlink channel information, including:

The terminal acquires downlink interference information, and sends the sounding pilot and the downlink interference information to the base station;

The base station obtains uplink channel state information according to the probing pilot, and obtains equivalent downlink channel state information according to the uplink channel state information;

The base station acquires downlink channel related information according to the equivalent downlink channel state information and the downlink interference information.

Further, the above method may also have the following feature, the downlink channel related information is precoding indication information and/or channel quality information and/or rank indication information.

Further, the above method may also have the following feature, the terminal acquires the downlink interference information according to the common pilot or the channel state information pilot sent by the base station.

Further, the above method may also have the following feature, the terminal alternately uses different antennas to send the probing pilot to the base station.

The present invention also provides a downlink channel information acquisition system, including a base station and a terminal, wherein:

The terminal is configured to obtain downlink interference information, and send sounding pilots and the downlink interference information to a base station;

The base station is configured to obtain uplink channel state information according to the sounding pilot, and obtain equivalent downlink channel state information according to the uplink channel state information; and obtain according to the equivalent downlink channel state information and the downlink interference information Downlink channel related information.

Further, the above-mentioned system may also have the following feature, the downlink channel-related information obtained by the base station is precoding indication information and/or channel quality information and/or rank indication information.

Further, the above system may also have the following features, the base station is also configured to send a common pilot or a channel state information pilot to the terminal;

The terminal is configured to acquire the downlink interference information according to the common pilot or the channel state information pilot sent by the base station.

Further, the above system may also have the following feature, the terminal is configured to alternately use different antennas to send the probing pilot to the base station.

Another technical problem to be solved by the present invention is to provide a method and system for acquiring uplink channel information, so as to reduce waste of resources.

In order to solve the above problems, the present invention provides a method for acquiring uplink channel information, including:

The base station acquires uplink interference information, and sends the uplink interference information and downlink pilot to the terminal;

The terminal obtains downlink channel state information according to the downlink pilot, and obtains equivalent uplink channel state information according to the downlink channel state information;

The terminal obtains uplink channel related information according to the equivalent uplink channel state information and the uplink interference information, and the uplink channel related information includes uplink channel quality information;

The terminal sends the uplink channel quality information to the base station.

Further, the above method may also have the following feature, the base station acquires the uplink interference information based on uplink service data or a virtual carrier.

Further, the above method may also have the following feature, the downlink pilot is a common pilot or a channel state information pilot.

The present invention also provides an uplink channel information acquisition system, including a base station and a terminal, wherein:

The base station is configured to acquire uplink interference information, and send the uplink interference information and downlink pilot to the terminal;

The terminal is configured to obtain downlink channel state information according to the downlink pilot, obtain equivalent uplink channel state information according to the downlink channel state information, and obtain equivalent uplink channel state information according to the equivalent uplink channel state information and the uplink interference information Acquire uplink channel related information, where the uplink channel related information includes uplink channel quality information, and send the uplink channel quality information to the base station.

Further, the above system may also have the following feature, the base station is configured to acquire the uplink interference information based on uplink service data or a virtual carrier.

Further, the above-mentioned system may also have the following feature, the downlink pilot sent by the base station is a common pilot or a channel state information pilot.

With the method and system of the present invention, since the acquisition of downlink channel related information does not need to feed back information such as PMI and CQI of the downlink channel, the amount of uplink feedback is greatly reduced, and at the same time, according to the reciprocity of the uplink and downlink channels Uplink channel information can obtain accurate downlink channel information. Compared with compressed PMI and CQI information, the base station can perform better resource scheduling and precoding and other related processing, thereby improving downlink transmission quality. For the acquisition of uplink channel related information, the present invention does not need to frequently send SRS for uplink channel measurement, so the uplink overhead brought by SRS can be greatly reduced.

Description of drawings

Fig. 1 is the flow chart of the downlink channel information acquisition method in the current LTE;

Fig. 2 is the flow chart of the method for acquiring uplink channel information in the current LTE;

Fig. 3 is a flowchart of a method for obtaining downlink channel information in the present invention;

Fig. 4 is a flowchart of a method for acquiring uplink channel information in the present invention.

Detailed ways

For the LTE/LTE-A-TDD system, since the uplink and downlink transmissions are located in the same frequency band, the uplink and downlink channels have reciprocity, that is, the uplink channel can be used to replace the downlink channel equivalently, or the downlink channel can be used to equivalently replace the downlink channel. Alternative uplink channel.

The present invention provides a method for obtaining downlink channel information by using channel reciprocity in TDD. The core idea is to feed back downlink interference information to the base station through the terminal, and the base station measures the uplink channel state information from the uplink detection pilot. The reciprocity of the channel and the downlink interference information fed back by the terminal obtain relevant information about the downlink channel, as shown in Figure 3. The method specifically includes the following steps:

Step 301, the base station sends the common pilot or the channel state information pilot to the terminal in the downlink;

Step 302, the terminal performs downlink interference estimation according to the common pilot or channel state information pilot sent by the base station, so as to obtain downlink interference information;

Step 303, the terminal sends a sounding pilot (SRS) to the base station on the uplink, and feeds back the measured downlink interference information to the base station;

Step 304, the base station measures the uplink channel according to the probing pilot sent by the terminal, so as to obtain uplink channel state information;

Step 305, according to channel reciprocity, the base station can obtain equivalent downlink channel state information according to the measured uplink channel state information;

Step 306: Based on the equivalent downlink channel state information and combined with the downlink interference information fed back by the terminal, the base station can obtain downlink channel related information, such as downlink channel quality information, precoding indication information, rank indication information, and the like.

Furthermore, in the LTE/LTE-A system, since the UE has fewer transmit antennas than its receive antennas, the uplink channel cannot include all downlink channels, that is to say, some downlink channels cannot be measured through the uplink channel. For this, in the present invention, the UE alternately uses different antennas to send probing pilots to the base station, and the base station can use channel reciprocity to obtain state information of all downlink channels.

Through the above method, the base station can accurately obtain relevant information of the downlink channel, and perform operations such as downlink resource scheduling, modulation and coding mode selection, and precoding.

The present invention also provides a method for obtaining uplink channel information by using channel reciprocity in TDD. The core idea is to send uplink interference information to the terminal through the base station, and the terminal transmits the downlink pilot (common pilot or channel state information) according to the downlink pilot sent by the base station. pilot frequency) to measure downlink channel status information, obtain uplink channel related information according to channel reciprocity and uplink interference information, and feed back uplink channel related information to the base station for uplink scheduling. Here, uplink channel related information refers to uplink channel quality Information, as shown in Figure 4, the method specifically includes the following steps:

Step 401, the base station performs uplink interference estimation and acquires uplink interference information;

Wherein, the base station may perform uplink interference estimation based on uplink service data, or based on virtual carrier and other methods.

For the method based on uplink business data, since the base station knows the modulation and coding mode of the uplink business data and other information, the base station can accurately calculate the useful signal power, and the base station can subtract the useful signal power from the total power of the measured uplink business data. Obtain the interference signal power to obtain uplink interference information;

For the method based on the virtual carrier, the signal power measured by the base station on the virtual carrier is the interference signal power, so as to obtain the uplink interference information.

Step 402, the base station sends downlink pilots to the terminal, and at the same time sends uplink interference information to the terminal;

The downlink pilot is a common pilot or a channel state information pilot;

Step 403, the terminal acquires downlink channel state information according to the downlink pilot sent by the base station;

Step 404, according to the reciprocity of the channel, the terminal acquires equivalent uplink channel state information according to the downlink channel state information;

Step 405, the terminal obtains uplink channel related information, such as uplink precoding information and channel quality information, according to the equivalent uplink channel state information and the uplink interference information sent by the base station;

Step 406, the terminal feeds back the uplink channel quality information to the base station.

Through the above method, the base station can obtain relevant information of the uplink channel, perform corresponding resource configuration and scheduling, and send uplink authorization information to the UE on the downlink, and the UE sends uplink service data according to the uplink authorization information.

In order to facilitate understanding of the present invention, the present invention will be further elaborated below in conjunction with specific examples.

Embodiment 1: method for acquiring downlink channel information

In this embodiment, the TDD system of LTE-A is taken as an example. Its downlink behavior is a multi-antenna scenario of 4 transmissions and 4 receptions, that is, four antennas at the base station side of the transmitting end transmit, and four antennas at the receiving end UE also receive reception. The channel is 4*4 matrix; while the above behavior is a multi-antenna scenario of 2 transmissions and 4 receptions, that is, the transmitting UE uses two antennas to transmit each time, and the receiving base station has 4 antennas to receive, and its channel is a 2*4 matrix.

In order to measure the downlink interference information, the base station sends CRS or CSI-RS to the UE in the downlink, and the UE measures the downlink interference information based on this, and feeds it back to the base station. Since only the downlink interference information needs to be fed back, compared with the prior art, the feedback is required Information such as PMI, CQI, and RI greatly reduces the uplink feedback overhead.

According to the present invention, the downlink channel state information is obtained from the uplink channel state information according to the reciprocity of TDD uplink and downlink channels. In order to obtain uplink channel state information, the UE sends SRS to the base station in the uplink, and the base station can obtain the uplink channel state information according to the SRS, and obtain the downlink channel state information equivalently according to the reciprocity of the uplink and downlink channels.

In this embodiment, since the downlink is a 4*4 channel and the uplink is a 2*4 channel, there is a problem that the uplink channel cannot include a complete downlink channel. According to the present invention, the UE can transmit the SRS in a manner of alternately using different antennas for transmission. Here, it is assumed that the four antennas at the UE are antenna 1, 2, 3, and 4, where antenna 1 and antenna 2 form a group, and antenna 3 and antenna 4 form a group. In this way, antenna 1 and antenna 2 can be selected in odd subframes. The SRS is sent, and the antenna 3 and the antenna 4 are selected to send the SRS in even subframes, so that the two measured uplink channels are combined to obtain an equivalent downlink channel.

After obtaining the state information of the downlink channel, and according to the downlink interference information fed back by the UE, accurate downlink channel precoding and channel quality related information can be obtained, and based on this, the base station configures downlink resources.

Embodiment 2: method for acquiring uplink channel information

This embodiment takes the LTE-TDD system as an example.

First, the base station performs uplink interference estimation and obtains uplink interference information;

Then, the base station sends the CRS and uplink interference information to the UE in the downlink, and the UE can measure the state information of the downlink channel according to the CRS, and obtain the equivalent state information of the uplink channel according to the reciprocity of the channel in TDD mode.

It should be noted that the number of downlink transmit antennas is usually more than the number of uplink antennas. For example, the downlink channel is a 4*4 matrix, while the uplink channel is a 1*4 matrix. The channel state information corresponding to the uplink is selected.

Secondly, after obtaining the state information of the uplink channel, and at the same time according to the uplink interference information sent by the base station, the UE can determine the quality information of the uplink channel and feed it back to the base station.

What needs to be explained here is that for the LTE-A system, when multi-antenna transmission is used in the uplink, the UE also needs to determine the precoding indication information, but does not need to feed it back to the base station, because the base station does not need the precoding indication information for uplink scheduling.

After obtaining the uplink channel quality information, the base station sends uplink authorization information to the UE, and the UE sends uplink service data according to the uplink authorization information.

Specific embodiments have been given above for the method for obtaining downlink channel information and the method for obtaining uplink channel information provided by the present invention. Based on the channel reciprocity characteristics of the TDD system, for the acquisition of downlink channel information, only the UE needs to feed back downlink interference information, and does not need to feed back a large amount of CQI/PMI and other information; for the acquisition of uplink channel information, there is no need to send SRS, only The base station needs to send the uplink interference information to the terminal, which saves uplink overhead.

It should be noted that any part of the present invention, combined with existing uplink/downlink channel information acquisition methods, can form a complete set of uplink and downlink channel acquisition methods, enabling the base station to perform accurate uplink and downlink resource scheduling and configuration. If the downlink channel information acquisition part of the present invention is combined with the existing LTE uplink channel acquisition method, a complete uplink and downlink channel acquisition method can be formed, so that the base station can perform correct uplink and downlink resource scheduling and configuration.

The present invention also provides a downlink channel information acquisition system, including a base station and a terminal, wherein:

The terminal is configured to obtain downlink interference information, and send sounding pilots and the downlink interference information to a base station;

The base station is configured to obtain uplink channel state information according to the sounding pilot, and obtain equivalent downlink channel state information according to the uplink channel state information; and obtain according to the equivalent downlink channel state information and the downlink interference information Downlink channel related information.

Wherein, the downlink channel-related information acquired by the base station is precoding indication information and/or channel quality information and/or rank indication information.

Wherein, the base station is further configured to send a common pilot or a channel state information pilot to the terminal;

The terminal is configured to acquire the downlink interference information according to the common pilot or the channel state information pilot sent by the base station.

Wherein, the terminal is configured to alternately use different antennas to send the probing pilot to the base station.

The present invention also provides an uplink channel information acquisition system, including a base station and a terminal, wherein:

The base station is configured to acquire uplink interference information, and send the uplink interference information and downlink pilot to the terminal;

The terminal is configured to obtain downlink channel state information according to the downlink pilot, obtain equivalent uplink channel state information according to the downlink channel state information, and obtain equivalent uplink channel state information according to the equivalent uplink channel state information and the uplink interference information Acquire uplink channel related information, where the uplink channel related information includes uplink channel quality information, and send the uplink channel quality information to the base station.

Wherein, the base station is configured to acquire the uplink interference information based on uplink service data or a virtual carrier.

Wherein, the downlink pilot sent by the base station is a common pilot or a channel state information pilot.

The present invention is not limited to the LTE/LTE-A TDD system, and other systems that satisfy the reciprocity of uplink and downlink channels are also suitable.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (14)

1. A method for acquiring downlink channel information, comprising: The terminal acquires downlink interference information, and sends the sounding pilot and the downlink interference information to the base station; The base station obtains uplink channel state information according to the probing pilot, and obtains equivalent downlink channel state information according to the uplink channel state information; the base station obtains downlink channel related information according to the equivalent downlink channel state information and the downlink interference information. 2. The method according to claim 1, wherein the downlink channel related information is precoding indication information and/or channel quality information and/or rank indication information. 3. The method according to claim 1, wherein the terminal acquires the downlink interference information according to a common pilot or channel state information pilot sent by the base station. 4. The method according to claim 1, 2 or 3, wherein the terminal alternately uses different antennas to send sounding pilots to the base station. 5. A downlink channel information acquisition system, characterized in that it includes a base station and a terminal, wherein: The terminal is configured to obtain downlink interference information, and send sounding pilots and the downlink interference information to a base station; The base station is configured to obtain uplink channel state information according to the sounding pilot, and obtain equivalent downlink channel state information according to the uplink channel state information; and obtain according to the equivalent downlink channel state information and the downlink interference information Downlink channel related information. 6. The system according to claim 5, wherein the downlink channel related information acquired by the base station is precoding indication information and/or channel quality information and/or rank indication information. 7. The system of claim 5, wherein: The base station is further configured to send a common pilot or a channel state information pilot to the terminal; The terminal is configured to acquire the downlink interference information according to the common pilot or the channel state information pilot sent by the base station. 8. The system according to claim 5, 6 or 7, wherein the terminal is configured to alternately use different antennas to send the sounding pilot to the base station. 9. A method for acquiring uplink channel information, comprising: The base station acquires uplink interference information, and sends the uplink interference information and downlink pilot to the terminal; The terminal obtains downlink channel state information according to the downlink pilot, and obtains equivalent uplink channel state information according to the downlink channel state information; The terminal obtains uplink channel related information according to the equivalent uplink channel state information and the uplink interference information, and the uplink channel related information includes uplink channel quality information; The terminal sends the uplink channel quality information to the base station. 10. The method according to claim 9, wherein the base station acquires the uplink interference information based on uplink service data or a virtual carrier. 11. The method according to claim 9 or 10, wherein the downlink pilot is a common pilot or a channel state information pilot. 12. A system for acquiring uplink channel information, comprising a base station and a terminal, wherein: The base station is configured to acquire uplink interference information, and send the uplink interference information and downlink pilot to the terminal; The terminal is configured to obtain downlink channel state information according to the downlink pilot, obtain equivalent uplink channel state information according to the downlink channel state information, and obtain equivalent uplink channel state information according to the equivalent uplink channel state information and the uplink interference information Acquire uplink channel related information, where the uplink channel related information includes uplink channel quality information, and send the uplink channel quality information to the base station. 13. The system according to claim 12, wherein the base station is configured to acquire the uplink interference information based on uplink service data or a virtual carrier. 14. The system according to claim 12 or 13, wherein the downlink pilot sent by the base station is a common pilot or a channel state information pilot.

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