CN110011706B - Method and device for optimizing cooperative transmission - Google Patents

Method and device for optimizing cooperative transmission Download PDF

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CN110011706B
CN110011706B CN201810012078.3A CN201810012078A CN110011706B CN 110011706 B CN110011706 B CN 110011706B CN 201810012078 A CN201810012078 A CN 201810012078A CN 110011706 B CN110011706 B CN 110011706B
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transmission
csi
channel
information
scheme
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CN110011706A (en
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佘锋
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Sanechips Technology Co Ltd
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Sanechips Technology Co Ltd
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    • 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
    • H04B7/022—Site diversity; Macro-diversity
    • H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
    • 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
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/0626—Channel coefficients, e.g. channel state information [CSI]
    • 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
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/063—Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
    • 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
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/0632—Channel quality parameters, e.g. channel quality indicator [CQI]
    • 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
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0636—Feedback format
    • H04B7/0639—Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
    • H04W72/542—Allocation or scheduling criteria for wireless resources based on quality criteria using measured or perceived quality
    • 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)
  • Mathematical Physics (AREA)
  • Quality & Reliability (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

A method and apparatus for optimizing cooperative transmission is disclosed. The method for optimizing cooperative transmission applied to the user equipment comprises the following steps: receiving measurement configuration information of a plurality of Channel State Information (CSI) processes sent by a service transmission node of a virtual cell, and performing channel estimation and measurement on a channel indicated by each CSI process; determining an optimal channel resource allocation scheme and a corresponding transmission scheme when two transmission nodes perform joint transmission according to the results of channel estimation and measurement; and generating CSI feedback information according to the optimal channel resource allocation scheme and the corresponding transmission scheme and sending the CSI feedback information to the service transmission node. The performance of coordinated multipoint transmission of a virtual cell centered on user equipment can be optimized.

Description

Method and device for optimizing cooperative transmission
Technical Field
The present invention relates to the field of wireless communications technologies, and in particular, to a method and an apparatus for optimizing cooperative transmission.
Background
In the design and deployment of an LTE (Long Term Evolution-Advanced) system and a 5G (Fifth Generation wireless communication system), multi-cell joint transmission has become an important transmission scheme in order to improve system capacity and coverage and effectively suppress interference. In transmission mode 10(TM10) of 3GPP (3rd Generation Partnership Project), release 10(rel.10), CoMP (Coordinated Multiple Point) has been supported.
As shown in fig. 1, one transmission scheme for CoMP is CSCB (Coordinated Scheduling/Beamforming, joint Scheduling/Beamforming). There are multiple TPs (Transmission points) in a cell, a serving node of the UE1 is TP1 (Transmission node 1), a serving node of the UE2 is TP2 (Transmission node 2), and communication between TP2 and the UE2 causes interference to communication between TP1 and UE 1. The UE1(User Equipment) measures Channel Information of TP1 and TP2 based on configuration Information of a serving TP1, and the serving TP1 cooperates based on CSI (Channel State Information) fed back by the UE1, for example, TP1 adjusts a beamforming vector of the UE1, and TP1 instructs TP2 to adjust the beamforming vector of the UE2, so as to achieve optimized transmission. As shown in fig. 1, the CSCB is characterized in that two transmission nodes (TP1 and TP2) respectively select optimal beamforming vectors for different UEs through coordination to reduce interference. Another transmission method of CoMP, namely, joint transmission, is also a research focus of LTE-a and 5G.
As shown in fig. 2, in the joint transmission, the UE1 measures channel information of the TP1 (transmission node 1) and the TP2 (transmission node 2) based on configuration information of the serving TP (transmission node 1), and feeds back CSI (channel state information) to the serving TP 1. The TP1 and TP2 jointly transmit data to the UE1 based on the fed back CSI information. Although the current protocol does not support joint transmission, joint transmission will be studied more deeply in future LTE-a successors and 5G ultra-dense deployments, and further, joint transmission is likely to be introduced into future communication protocols.
The current CoMP scheme mainly aims to solve the interference cancellation and coverage problem of the cell edge UE. However, in future 5G ultra-dense networking deployments, virtual cells will be formed with the UE as the center, as shown in fig. 3, and under the ultra-dense network deployments, the virtual cells are dynamically formed with the UE as the center. Thus, the UE will be in the center of the virtual cell rather than the cell edge. After forming the virtual cell, a plurality of TPs in the virtual cell constitute a cooperation set, where one TP is a serving TP and the remaining TPs are cooperation TPs. The serving TP is primarily responsible for controlling the transmission of channels, receiving CSI feedback, scheduling other cooperating TPs. Based on this situation, it would appear more necessary to implement a joint transmission scheme of multiple transmission nodes (TPs) in a virtual cell. And the virtual cell is dynamically formed based on CSI measurement and reporting of the UE. The UE receives cell search signals of a plurality of TPs, and based on the search signals, the UE selects a TP with the strongest signal as a serving TP. The serving TP acquires signal strength and forms a virtual cell. The service TP and other cooperating TPs complete the establishment of the cooperation set through the X2 interface, followed by the transport phase. In joint transmission of multiple TPs, multiple TPs may implement transmission based on different resource allocation schemes.
In the related CoMP transmission scheme, the determination from the formation of the cooperative cell to the cooperative transmission scheme is centered on the base station, and in the conventional CoMP scheme, the base station needs to form the transmission scheme and resource allocation based on the global channel information. In practical systems, this requires a large feedback overhead, which is not practical in LTE and 5G systems. Also, since the quantized channel information is not accurate, it may also have an impact on performance. Therefore, the base station-centric strategy does not effectively support coordinated multi-point transmission of UE-centric virtual cells.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a method and an apparatus for optimizing cooperative transmission, which can optimize the performance of coordinated multi-point transmission of a virtual cell with user equipment as the center.
The embodiment of the invention provides a method for optimizing cooperative transmission, which is applied to user equipment and comprises the following steps:
receiving measurement configuration information of a plurality of Channel State Information (CSI) processes sent by a service transmission node of a virtual cell, and performing channel estimation and measurement on a channel indicated by each CSI process;
determining an optimal channel resource allocation scheme and a corresponding transmission scheme when two transmission nodes perform joint transmission according to the results of channel estimation and measurement;
and generating CSI feedback information according to the optimal channel resource allocation scheme and the corresponding transmission scheme and sending the CSI feedback information to the service transmission node.
The embodiment of the invention provides a method for optimizing cooperative transmission, which is applied to a service transmission node and comprises the following steps:
sending measurement configuration information of a plurality of CSI processes to user equipment in a virtual cell;
after receiving Channel State Information (CSI) fed back by the user equipment, determining an optimal transmission scheme when a service transmission node and a cooperative transmission node perform joint transmission, and informing the cooperative transmission node and the user equipment; the CSI fed back by the user equipment comprises information of an optimal resource allocation scheme and a transmission scheme when the two transmission nodes determined by the user equipment are jointly transmitted.
The embodiment of the invention provides a device for optimizing cooperative transmission, which is applied to user equipment and comprises the following components:
the measurement and estimation module is used for receiving measurement configuration information of a plurality of Channel State Information (CSI) processes sent by a service transmission node of a virtual cell and carrying out channel estimation and measurement on a channel indicated by each CSI process;
the optimization module is used for determining an optimal channel resource allocation scheme and a corresponding transmission scheme when the two transmission nodes perform combined transmission according to the results of channel estimation and measurement;
and the feedback module is used for generating CSI feedback information according to the optimal channel resource allocation scheme and the corresponding transmission scheme and sending the CSI feedback information to the service transmission node.
The embodiment of the invention provides a device for optimizing cooperative transmission, which is applied to a service transmission node and comprises the following components:
a configuration module, configured to send measurement configuration information of a plurality of CSI processes to a ue in a virtual cell;
the feedback information receiving and processing module is used for determining an optimal transmitting scheme when the service transmission node and the cooperative transmission node perform joint transmission after receiving the Channel State Information (CSI) fed back by the user equipment, and informing the cooperative transmission node and the user equipment; the CSI fed back by the user equipment comprises information of an optimal resource allocation scheme and a transmission scheme when the two transmission nodes determined by the user equipment are jointly transmitted.
Compared with the related art, according to the method and the device for optimizing cooperative transmission provided by the embodiment of the invention, the user equipment performs channel estimation and measurement on the channel indicated by each CSI process according to the CSI process measurement configuration information configured by the service transmission node of the virtual cell, determines the optimal channel resource allocation scheme and the corresponding transmission scheme when the two transmission nodes perform joint transmission according to the result of the channel estimation and measurement, generates CSI feedback information according to the optimal channel resource allocation scheme and the corresponding transmission scheme, and sends the CSI feedback information to the service transmission node. The embodiment of the invention can optimize the performance of the multipoint cooperative transmission of the virtual cell taking the user equipment as the center.
Drawings
Fig. 1 is a schematic diagram of a coordinated multi-point transmission scheme for joint scheduling/beamforming in the related art;
fig. 2 is a diagram illustrating a coordinated multi-point transmission scheme of joint transmission in the related art;
fig. 3 is a diagram illustrating a virtual cell in the related art;
fig. 4 is a flowchart of a method for optimizing cooperative transmission (ue) in embodiment 1 of the present invention;
fig. 5 is a flowchart of a method for optimizing cooperative transmission (serving transport node) in embodiment 2 of the present invention;
fig. 6 is a schematic diagram of an apparatus (user equipment) for optimizing cooperative transmission according to embodiment 3 of the present invention;
fig. 7 is a schematic diagram of an apparatus for optimizing cooperative transmission (service transmission node) according to embodiment 4 of the present invention;
fig. 8 is a schematic diagram of information interaction of a method for optimizing cooperative transmission according to example 1 of the present invention;
fig. 9 is a flow chart of a method of optimizing cooperative transmission of example 2 of the present invention;
fig. 10 is a diagram of a resource allocation indication bitmap in example 2 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.
Example 1
As shown in fig. 4, an embodiment of the present invention provides a method for optimizing cooperative transmission, which is applied to a user equipment, and includes:
step S410, receiving measurement configuration information of a plurality of CSI processes sent by a service transmission node of a virtual cell, and performing channel estimation and measurement on a channel indicated by each CSI process;
step S420, determining an optimal channel resource allocation scheme and a corresponding transmission scheme when the two transmission nodes perform joint transmission according to the results of channel estimation and measurement;
step S430, generating CSI feedback information according to the optimal channel resource allocation scheme and the corresponding transmission scheme and sending the CSI feedback information to the service transmission node;
in this embodiment, the measurement configuration information of each CSI process includes at least one of the following information: the method comprises the steps that identification of a transmission node corresponding to a channel for channel estimation and measurement is carried out, the number of ports of a channel state information reference signal (CSI-RS), the period of the CSI-RS, time domain indication information of the CSI-RS and subframe set indication information for measuring and estimating the channel by user equipment are carried out; wherein the CSI-RS comprises a non-zero power CSI-RS and a zero power CSI-RS;
the time domain indication information of the CSI-RS can indicate the frame position where the CSI-RS is located;
in this embodiment, the measurement configuration information of the CSI process may be transmitted through an RRC (Radio Resource Control) signaling;
in this embodiment, the channel estimation and measurement on the channel indicated by each CSI process may be performed by using algorithms such as LS (Least Square), MMSE (minimum Mean Square Error, based on minimum Mean Square Error) in the prior art.
In this embodiment, the determining an optimal channel resource allocation scheme and a corresponding transmission scheme when two transmission nodes perform joint transmission according to the results of channel estimation and measurement includes:
selecting a candidate channel resource group with the channel quality meeting the requirement according to the results of channel estimation and measurement;
determining SINRs (Signal to Interference plus Noise Ratio) under different transmission schemes when two transmission nodes jointly transmit according to the candidate channel resource group, and determining system capacity according to the SINRs;
selecting a resource combination and a transmission scheme when two transmission nodes with the maximum system capacity are jointly transmitted as an optimal channel resource allocation scheme and a corresponding transmission scheme;
wherein the transmission scheme comprises: diversity transmission or multiplexing transmission.
In this embodiment, selecting a candidate channel resource group whose channel quality meets the requirement according to the channel estimation and measurement results includes: selecting a channel with SINR (Signal to Interference plus Noise Ratio) exceeding a threshold as a candidate channel resource; the SINR of the channel may be calculated by a method in the prior art.
In this embodiment, the CSI feedback information includes: a resource allocation Indication and a transmission scheme Indication of two transmission nodes performing joint transmission, a PMI (Precoding matrix Indicator), an RI (Rank Indicator), and a CQI (Channel Quality Indicator) of each transmission node;
the resource allocation indication indicates information of a sub-band recommended to be transmitted by each transmission node in a bitmap mode; the widths of sub-bands of bitmaps corresponding to different transmission nodes are the same or different;
in an embodiment, after generating CSI feedback information according to the optimal channel resource allocation scheme and the corresponding transmission scheme and sending the CSI feedback information to the serving transmission node, the method further includes:
receiving signaling information of the service node, wherein the signaling information indicates the information of an optimal transmission scheme determined by the service node according to CSI fed back by user equipment; wherein, since one virtual cell may serve multiple cells, the virtual cell determines the final transmission scheme and signals an indication to the UE to implement the optimization of the transmission scheme.
Wherein the signaling comprises: DCI (Downlink Control Information) signaling or higher layer signaling.
Example 2
As shown in fig. 5, an embodiment of the present invention provides a method for optimizing cooperative transmission, which is applied to a service transmission node, and includes:
step S510, sending measurement configuration information of a plurality of CSI processes to user equipment in a virtual cell;
step S520, after receiving the channel state information CSI fed back by the user equipment, determining an optimal transmission scheme when a service transmission node and a cooperative transmission node perform joint transmission, and notifying the cooperative transmission node and the user equipment; the CSI fed back by the user equipment comprises information of an optimal resource allocation scheme and a transmission scheme when the two transmission nodes determined by the user equipment are in joint transmission;
in this embodiment, the measurement configuration information of each CSI process includes at least one of the following information: the method comprises the steps that identification of a transmission node corresponding to a channel for channel estimation and measurement is carried out, the number of ports of a channel state information reference signal (CSI-RS), the period of the CSI-RS, time domain indication information of the CSI-RS and subframe set indication information for measuring and estimating the channel by user equipment are obtained; wherein the CSI-RS comprises a non-zero power CSI-RS and a zero power CSI-RS;
in this embodiment, the measurement configuration information of the CSI process may be transmitted through an RRC (Radio Resource Control) signaling;
in this embodiment, the notifying cooperative transmission node includes: sending a message to a cooperative transmission node through an X2 interface to indicate the information of the optimal transmission scheme when two transmission nodes jointly transmit;
in this embodiment, the notifying the user equipment includes: informing the user equipment of the Information of the optimal transmission scheme during the joint transmission of the two transmission nodes through DCI (Downlink Control Information) signaling or high-level signaling;
wherein, the information of the optimal transmission scheme when the two transmission nodes jointly transmit comprises: a resource allocation indication and a transmission mode indication of the optimal transmission scheme;
after receiving the CSI fed back by the ue, determining an optimal transmission scheme for joint transmission by two transmission nodes, including: and determining an optimal transmission scheme for joint transmission of two transmission nodes serving the user equipment according to a scheduling algorithm based on the channel information and the resource conditions of the plurality of user equipment.
Example 3
As shown in fig. 6, an apparatus for optimizing cooperative transmission according to an embodiment of the present invention is applied to a user equipment, and includes:
a measurement and estimation module 601, configured to receive measurement configuration information of multiple CSI processes sent by a serving transmission node of a virtual cell, and perform channel estimation and measurement on a channel indicated by each CSI process;
an optimizing module 602, configured to determine, according to results of channel estimation and measurement, an optimal channel resource allocation scheme and a corresponding transmission scheme for joint transmission of two transmission nodes;
a feedback module 603, configured to generate CSI feedback information according to the optimal channel resource allocation scheme and the corresponding transmission scheme, and send the CSI feedback information to the serving transmission node.
In one embodiment, the measurement configuration information of each CSI process includes at least one of the following information: the method comprises the steps that identification of a transmission node corresponding to a channel for channel estimation and measurement is carried out, the number of ports of a channel state information reference signal (CSI-RS), the period of the CSI-RS, time domain indication information of the CSI-RS and subframe set indication information for measuring and estimating the channel by user equipment are obtained; wherein the CSI-RS comprises a non-zero power CSI-RS and a zero power CSI-RS.
In one embodiment, the optimization module is configured to determine an optimal channel resource allocation scheme and a corresponding transmission scheme for joint transmission by two transmission nodes according to the results of channel estimation and measurement in the following manner:
selecting a candidate channel resource group with the channel quality meeting the requirement according to the results of channel estimation and measurement;
determining a signal to interference plus noise ratio (SINR) under different transmission schemes when two transmission nodes jointly transmit according to the candidate channel resource group, and determining system capacity according to the SINR;
selecting a resource combination and a transmission scheme when two transmission nodes with the maximum system capacity are jointly transmitted as an optimal channel resource allocation scheme and a corresponding transmission scheme;
wherein the transmission scheme comprises: diversity transmission or multiplexing transmission.
In one embodiment, the CSI feedback information includes: resource allocation indication and transmission scheme indication of two transmission nodes performing joint transmission, wherein a Precoding Matrix Indication (PMI), a Rank Indication (RI) and a Channel Quality Indication (CQI) of each transmission node are obtained;
the resource allocation indication indicates information of a sub-band recommended to be transmitted by each transmission node in a bitmap mode; the widths of the sub-bands of the bitmaps corresponding to different transmission nodes are the same or different.
In one embodiment, the apparatus further comprises:
and the receiving module is used for generating CSI feedback information according to the optimal channel resource allocation scheme and the corresponding transmission scheme, sending the CSI feedback information to the service transmission node, and then receiving the signaling information of the service node, wherein the signaling information indicates the information of the optimal transmission scheme determined by the service node according to the CSI fed back by the user equipment.
Example 4
As shown in fig. 7, an apparatus for optimizing cooperative transmission according to an embodiment of the present invention includes:
a configuration module 701, configured to send measurement configuration information of multiple CSI processes to a ue in a virtual cell;
a feedback information receiving and processing module 702, configured to determine an optimal transmission scheme for joint transmission between a serving transmission node and a cooperative transmission node after receiving channel state information CSI fed back by the user equipment, and notify the cooperative transmission node and the user equipment; the CSI fed back by the user equipment comprises information of an optimal resource allocation scheme and a transmission scheme when the two transmission nodes determined by the user equipment are jointly transmitted.
In this embodiment, the measurement configuration information of each CSI process includes at least one of the following information: the method comprises the steps that identification of a transmission node corresponding to a channel for channel estimation and measurement is carried out, the number of ports of a channel state information reference signal (CSI-RS), the period of the CSI-RS, time domain indication information of the CSI-RS and subframe set indication information for measuring and estimating the channel by user equipment are carried out; wherein the CSI-RS comprises a non-zero power CSI-RS and a zero power CSI-RS;
in this embodiment, the measurement configuration information of the CSI process may be transmitted through an RRC (Radio Resource Control) signaling;
in this embodiment, the feedback information receiving and processing module is configured to notify the cooperative transmission node in the following manner: sending a message to a cooperative transmission node through an X2 interface to indicate information of an optimal transmission scheme when two transmission nodes perform joint transmission;
in this embodiment, the feedback information receiving and processing module is configured to notify the user equipment in the following manner: informing the user equipment of the Information of the optimal transmission scheme during the joint transmission of the two transmission nodes through DCI (Downlink Control Information) signaling or high-level signaling;
wherein, the information of the optimal transmission scheme when the two transmission nodes jointly transmit comprises: a resource allocation indication and a transmission mode indication of the optimal transmission scheme;
the feedback information receiving and processing module is configured to determine, after receiving the CSI fed back by the user equipment, an optimal transmission scheme for joint transmission between two transmission nodes in the following manner: and determining an optimal transmission scheme for joint transmission of two transmission nodes serving the user equipment according to a scheduling algorithm based on the channel information and the resource condition of the plurality of user equipment.
The following further illustrates an optimization method of the coordinated transmission scheme of the UE-centric virtual cell by way of example.
Example 1
After a virtual cell (cooperative cell) has been formed, in order to optimize a transmission scheme of the virtual cell with the UE as a center, a conventional base station and the UE are functionally enhanced. Specifically, the enhancement of the base station mainly comprises that related signaling which is centered on the UE can be received, processed and configured; the enhancement of the UE mainly comprises transmission mode optimization calculation, resource allocation and feedback information.
As shown in fig. 6, the procedure for optimizing cooperative transmission proposed by this example may include the following steps:
s101, a service TP sends channel measurement configuration information to UE to indicate the UE to carry out channel measurement and estimation;
s102, the UE carries out channel estimation and measurement according to the received channel measurement configuration information;
s103, the UE performs optimization calculation based on a specific criterion according to the results of channel estimation and measurement to form an optimized transmission scheme and a resource allocation scheme;
and S104, the UE forms the enhanced CSI according to the formed optimized transmission scheme and the resource allocation scheme. Wherein the enhanced CSI comprises a resource indication and a transmission scheme indication.
S105, the service TP optimizes the transmission mode according to the enhanced CSI and sends the related signaling of the transmission mode optimization to the UE.
Example 2
In this example, after a virtual cell (cooperative cell) has been formed, resource allocation and optimization of a cooperative transmission scheme are formed by enhancing calculation and feedback on the UE side.
As shown in fig. 10, the processing flow of the present example includes the following steps:
s101, the serving TP sends channel measurement configuration information to the UE.
The Channel measurement configuration Information may include a plurality of CSI process configurations, and each CSI process configuration includes a CSI-RS (Channel State Information-Reference Signal) for measuring non-zero power of a Signal and a CSI-RS for measuring zero power of interference.
The configuration of each CSI may also include one subframe set. Since one serving TP may serve multiple UEs, different UEs perform measurement and estimation of interference and channel in different subframe sets, any UE needs to perform measurement and estimation of interference and channel in the subframe set corresponding to the UE.
And S102, the UE carries out channel estimation and measurement aiming at each CSI process.
According to the channel measurement configuration information sent by the service TP, the UE performs channel estimation and measurement on the TP indicated in the channel measurement configuration information according to the existing algorithms such as LS (Least Square), MMSE (minimum Mean Square Error) and the like. Since channel estimation algorithms such as LS, MMSE, etc. belong to the prior art, this step will not be described in detail.
S103, the UE performs transmission scheme optimization calculation and enhanced CSI calculation.
The UE may perform the transmission scheme optimization calculation and the enhanced CSI calculation according to the following steps:
step 1: after the UE completes channel estimation and interference measurement of all CSI processes, a plurality of candidate channel resource sets are determined, and the selected basis may be channel quality.
Step 2: aiming at each candidate channel resource group, calculating the system capacity of the candidate channel resource group under different transmission schemes; wherein the transmission scheme comprises: diversity transmission or multiplex transmission; the diversity transmission is to transmit the same data on a plurality of independent paths, and a receiving end resists channel fading through a diversity combining technology, thereby improving the transmission reliability and reducing the error rate. Multiplexing transmission is to transmit different data on multiple independent paths, fully utilize system resources, and improve system capacity.
The method for calculating the system capacity of one candidate channel resource group in a diversity or multiplexing transmission mode comprises the following steps: sending the received signals of the service TP and the cooperative TP in the candidate channel resource group received by the UE into a MIMO (Multiple-Input Multiple-Output) receiver, obtaining the SINR (Signal to Interference plus Noise Ratio) of the Signal of each layer of the MIMO receiver, and calculating the system capacity according to the SINR of each layer of the Signal of the spatial demodulator; in general, diversity transmission and multiplexing transmission may employ different MIMO receivers; diversity transmission may employ a maximum ratio combining receiver, while multiplexed transmission may employ an MMSE receiver or a sphere decoding receiver.
In a multi-TP system, for a transmission mode that a transmitting end adopts multiplexing, H is assumed 0 And H 1 Channel estimation for a serving TP and a cooperative TP in the candidate channel resource group respectively, based on the estimated H of the UE 0 And H 1 The reception model of the UE is shown in the following formula (1-1);
Y＝H 0 x 0 +H 1 x 1 +n (1-1)
wherein x is 0 And x 1 Respectively, a transmitting signal, n is a noise signal, and Y is a receiving signal of the UE;
in the multiplexing transmission mode, taking the most basic MMSE receiving algorithm as an example, the signal passing through the i-th layer of the MMSE spatial demodulator is shown in the following formula (1-2):
wherein,
Figure BDA0001540659860000121
wherein x is i Is the signal of the i-th layer passing through the MMSE spatial demodulator, y is the received signal of the UE, vector v H Indicating MMSE linear processing corresponding to the ith layer. h is i Is the ith column of H matrix, which is the channel matrix estimated by UE, N is the number of layers of spatial demodulator, K i Which represents the receiving operator, the operator is,
Figure BDA0001540659860000122
representing the noise power, I M Unit matrix, P, representing MxM t Represents the transmission power of each antenna, (. cndot.) H Is a conjugate operation, wherein (·)' is the transposition of a matrix, (·) -1 Is the inverse of the matrix.
The SINR of the i-th layer of the spatial demodulator is shown in the following formulas (1-3);
Figure BDA0001540659860000123
in the multiplexing transmission scheme, the system capacity is calculated according to the SINR of each layer signal of the MMSE receiver, and may be calculated by using the following formulas (1-4):
Figure BDA0001540659860000124
wherein, C MMSE Is the system capacity, E (-) is the mathematical expectation operation, lb (-) is the base 2 logarithm operation;
in the multi-TP system, for the transmission mode adopting diversity at the transmitting end, the MIMO receiver adopted by the receiving end is assumed to be the maximum ratio combining receiver, and H is assumed 0 And H 1 Channel estimation for a serving TP and a cooperative TP in the candidate channel resource group respectively, based on H estimated by UE 0 And H 1 The reception model of the UE is shown in the following formula (2-1);
Y＝H 0 x+H 1 x+n 0 ＝(H 0 +H 1 )x+n 0 ＝H'x+n 0 (2-1)
where x is the transmitted signal and n 0 Is a noise signal, Y is a received signal, H' is a combined equivalent channel estimate;
in the diversity transmission mode, the SINR obtained by using the maximum ratio combining algorithm is shown in the following formula (2-2):
SINR＝(H' H H'x)/N 0 (2-2)
wherein N is 0 Is the noise power, (.) H Taking conjugate operation;
based on the shannon formula, the channel capacity for obtaining diversity transmission is shown in the following formula (2-3):
C＝lb(1+SINR)＝lb(1+(H' H H'x)/N 0 ) (2-3)
where C is the system capacity and lb (-) is a base 2 logarithm operation.
And step 3: and determining the channel resource group with the maximum system capacity and the transmission scheme as the optimal channel resource group and the optimal transmission scheme by comparing the system capacities of the plurality of candidate channel resource groups under different transmission schemes.
Wherein, the resources of the two TPs may completely overlap, or partially overlap, or be independent of each other in the frequency domain. When the resources of the two TPs are completely or partially overlapped in the frequency domain, a MIMO receiver model is used to calculate the system capacity. When the resources of two TPs are independent from each other in the frequency domain, only the channel capacities of the individual TPs need to be calculated separately and then summed.
S104: the UE performs enhanced CSI feedback;
wherein the enhanced CSI feedback is formed to indicate resource allocation based on the optimal resources.
The resource allocation indication may be implemented based on a plurality of bitmaps. The UE may form a bitmap for each TP. The principle of the bitmap is shown in fig. 10. For a serving TP (e.g., TP0) and a cooperating TP (e.g., TP1), a bitmap may be considered, respectively. The entire bandwidth of TP0 and TP1 may be divided into multiple sub-bands, with the shaded portions being the sub-bands with better channel conditions. As shown in fig. 10(a), the subband widths of two TPs are the same, and for TP0, the recommended subband resource may be indicated with 8 bits: 11010000, wherein a "1" indicates that the sub-band is recommended and a "0" indicates that the sub-band is not recommended; likewise, the recommended subband resources for TP1 may be indicated with bit 01011000. As shown in fig. 10(b), the subband widths of two TPs are not the same, and the recommended subband resource of TP0 may be indicated by 8 bits "11010000", and the recommended subband resource of TP1 may be indicated by 8 bits "01010000".
The enhanced feedback further comprises: a plurality of PMIs (Precoding Matrix indicators) for supporting Precoding indication of a plurality of TPs in an optimized transmission mode; an enhanced RI (Rank Indication) including RIs of a plurality of TPs to indicate different numbers of layers; the enhanced multiple CQI (Channel Quality Indicator) is a quantization result based on the SINR calculated in the previous step, and is used to instruct the base station to select an appropriate modulation scheme.
Step S105: the serving TP determines the optimal transmission scheme and informs the cooperating TPs and UEs.
Since one virtual cell may serve multiple cells, the final transmission scheme is determined by the virtual cell and signaled to the cooperating TPs and UEs to implement the optimization of the transmission scheme. This step includes two parts:
and (3) multi-TP cooperation: the method comprises the steps that a service TP optimizes a transmission mode based on feedback CSI, and comprises the steps of selecting a proper resource allocation mode and RI indication; the service TP indicates the transport mode to the cooperating TP via an X2 interface.
And signaling indication: indicating the resource allocation modes of the two TPs to the UE through DCI or high-level signaling; transmission mode, precoding information, RI information.
It is to be noted that the present invention may be embodied in other specific forms, and that various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (10)

1. A method for optimizing cooperative transmission is applied to user equipment and comprises the following steps:
receiving measurement configuration information of a plurality of CSI processes sent by a service transmission node of a virtual cell, and performing channel estimation and measurement on a channel indicated by each CSI process;
determining an optimal channel resource allocation scheme and a corresponding transmission scheme when two transmission nodes perform joint transmission according to the results of channel estimation and measurement;
and generating CSI feedback information according to the optimal channel resource allocation scheme and the corresponding transmission scheme and sending the CSI feedback information to the service transmission node.
2. The method of claim 1, wherein:
the measurement configuration information of each CSI process includes at least one of the following information: the method comprises the steps that identification of a transmission node corresponding to a channel for channel estimation and measurement is carried out, the number of ports of a channel state information reference signal (CSI-RS), the period of the CSI-RS, time domain indication information of the CSI-RS and subframe set indication information for measuring and estimating the channel by user equipment are carried out; wherein the CSI-RS comprises a non-zero power CSI-RS and a zero power CSI-RS.
3. The method of claim 1, wherein:
the determining an optimal channel resource allocation scheme and a corresponding transmission scheme when two transmission nodes perform joint transmission according to the results of channel estimation and measurement includes:
selecting a candidate channel resource group with the channel quality meeting the requirement according to the results of channel estimation and measurement;
determining a signal to interference plus noise ratio (SINR) under different transmission schemes when two transmission nodes jointly transmit according to the candidate channel resource group, and determining system capacity according to the SINR;
selecting a resource combination and a transmission scheme when two transmission nodes with the maximum system capacity are jointly transmitted as an optimal channel resource allocation scheme and a corresponding transmission scheme;
wherein the transmission scheme comprises: diversity transmission or multiplexing transmission.
4. The method of claim 1, wherein:
the CSI feedback information includes: resource allocation indication and transmission scheme indication of two transmission nodes performing joint transmission, wherein a Precoding Matrix Indication (PMI), a Rank Indication (RI) and a Channel Quality Indication (CQI) of each transmission node are obtained;
the resource allocation indication indicates information of a sub-band recommended to be transmitted by each transmission node in a bitmap mode; the widths of the sub-bands of the bitmaps corresponding to different transmission nodes are the same or different.
5. The method of claim 1, wherein after generating CSI feedback information according to the optimal channel resource allocation scheme and the corresponding transmission scheme and transmitting the CSI feedback information to the serving transmission node, the method further comprises:
and receiving signaling information of the service transmission node, wherein the signaling information indicates the information of the optimal transmission scheme determined by the service transmission node according to the CSI fed back by the user equipment.
6. A method for optimizing cooperative transmission is applied to a service transmission node and comprises the following steps:
sending measurement configuration information of a plurality of CSI processes to user equipment in a virtual cell;
after receiving the channel state information CSI fed back by the user equipment, determining an optimal transmission scheme when a service transmission node and a cooperative transmission node perform joint transmission, and informing the cooperative transmission node and the user equipment; the CSI fed back by the user equipment comprises information of an optimal resource allocation scheme and a transmission scheme when the two transmission nodes determined by the user equipment are in joint transmission.
7. The method of claim 6, wherein:
the measurement configuration information of each CSI process includes at least one of the following information: the method comprises the steps that identification of a transmission node corresponding to a channel for channel estimation and measurement is carried out, the number of ports of a channel state information reference signal (CSI-RS), the period of the CSI-RS, time domain indication information of the CSI-RS and subframe set indication information for measuring and estimating the channel by user equipment are obtained; wherein the CSI-RS comprises a non-zero power CSI-RS and a zero power CSI-RS.
8. The method of claim 6, wherein:
the information of the optimal transmission scheme when the two transmission nodes jointly transmit comprises: a resource allocation indication and a transmission mode indication of the optimal transmission scheme.
9. An apparatus for optimizing cooperative transmission, applied to a user equipment, comprising:
the measurement and estimation module is used for receiving measurement configuration information of a plurality of Channel State Information (CSI) processes sent by a service transmission node of a virtual cell and carrying out channel estimation and measurement on a channel indicated by each CSI process;
the optimization module is used for determining an optimal channel resource allocation scheme and a corresponding transmission scheme when the two transmission nodes perform combined transmission according to the results of channel estimation and measurement;
and the feedback module is used for generating CSI feedback information according to the optimal channel resource allocation scheme and the corresponding transmission scheme and sending the CSI feedback information to the service transmission node.
10. An apparatus for optimizing cooperative transmission, applied to a service transmission node, includes:
a configuration module, configured to send measurement configuration information of a plurality of CSI processes to a ue in a virtual cell;
the feedback information receiving and processing module is used for determining an optimal transmitting scheme when a service transmission node and a cooperative transmission node perform joint transmission after receiving Channel State Information (CSI) fed back by the user equipment, and informing the cooperative transmission node and the user equipment; the CSI fed back by the user equipment comprises information of an optimal resource allocation scheme and a transmission scheme when the two transmission nodes determined by the user equipment are jointly transmitted.
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