CN102013952A - Method for acquiring channel state information, base station and user equipment - Google Patents

Abstract

The invention discloses a method for acquiring channel state information, a base station and user equipment. In the invention, CoMP (Coordinated Multi-Point) user equipment can adopt an SRS (Sounding Reference Signal) mode based on a service cell or an SRS mode based on CoMP. The base station detects uplink SRS transmitted by the user equipment and acquires the channel state information according to the detected SRS. Then, the base station performs resource scheduling together with other base stations on the basis of the channel state information required by the resource allocation, exchanges scheduling information and/or data required to be transmitted cooperatively after joint resource scheduling with other base stations and carries out the transmitting mode selection, power allocation and transmitter optimization together with the other base stations. Finally, the base station transmits data and/or signaling to the user equipment. The invention has the characteristics of simple structure, completion and high efficiency and is easy for realization.

Description

Channel state information acquisition method, base station and user equipment

Technical Field

The present invention relates to the field of wireless technology transmission, and in particular, to a method, a base station, and a user equipment for acquiring channel state information based on a Sounding Reference Signal (SRS).

Background

As personal or mobile communication devices have demanded the capability of broadband services such as multimedia services, online gaming, video on demand, and mobile television, wider system frequency bands, higher peak rates, and better edge quality of service have become an important requirement for future personal or mobile communication systems. The 3GPP (third generation partnership project) organization is the very international organization that is dedicated to the standardization work of personal or mobile communications. The 3GPP organization has designed EUTRA (evolved universal mobile telecommunications system and terrestrial radio access) and EUTRAN (evolved universal mobile telecommunications system network and terrestrial radio access network) from the second half of 2004, which is also referred to as the LTE (long term evolution) project. In the 4 th month of 2008, the 3GPP organization began to discuss standardization work of the fourth generation (4G) cellular communication system in the Shenzhen conference in china, and for this purpose, the 3GPP organization defined LTE-Advanced (LTE-a) as a version evolving from the current 3GPP LTE8.0 version to the future 4G version.

A system based on LTE-Advanced (LTE-a) version is required to have not only the capability of backward compatibility with a system based on LTE8.0 (LTE) version, but also higher downlink data rate at the cell center and downlink data rate at the cell edge, and thus a technical concept called "Coordinated Multi-point Transmission/Reception (CoMP)" is widely focused and supported. Coordinated multipoint (CoMP) transmission/reception is considered in LTE-a systems as a tool to provide high data rates, improve cell-edge throughput, and/or system throughput. The core idea of CoMP transmission/reception is that through cooperation between multiple Base Stations (BS) and multiple User Equipments (UE), not only the data rate of the cell center and the data rate of the cell edge are simultaneously increased, but also the co-channel interference widely existing among wireless cells is greatly suppressed. In addition, Multiple Input Multiple Output (MIMO) technology, which is the most important means for increasing the transmission rate of a system, can increase the capacity and the spectrum utilization rate of a communication system by a Multiple without increasing the system bandwidth, and therefore, the MIMO technology is a key technology that must be adopted in a new generation of mobile communication system, and this point has become common knowledge and receives a lot of attention. Furthermore, Orthogonal Frequency Division Multiplexing (OFDM) technology has strong anti-fading capability and high frequency utilization rate, and is suitable for high-speed data transmission in multipath environment and fading environment, so MIMO-OFDM technology, which combines MIMO technology and OFDM technology, has become the core technology of new-generation mobile communication. In addition, since the Single Carrier (SC) transmission technique has a characteristic of low PAPR/CM (peak-to-average ratio/cubic metric), various communication companies have gradually agreed with an uplink multiple access technique of frequency domain SC-FDMA (single carrier-frequency division multiple access) in which the DFT-S-OFDM (discrete fourier transform spread orthogonal frequency division multiplexing) is adopted as a core for the uplink of LTE or LTE-a. Finally, in order to further improve the performance of the LTE-a system greatly, the 3GPP has determined that the downlink bandwidth of the LTE-a system will adopt a spectrum Aggregation (Carrier Aggregation) technique as early as in the RAN1#53bis conference, and combine a plurality of continuous or discontinuous 20MHz frequency bands into a system bandwidth of downlink 100MHz or a system bandwidth of uplink greater than 20MHz, which also affects the CoMP scheme.

The present invention finds, through investigation and analysis of the prior art documents, a method for acquiring Channel State Information (CSI) and a method for designing Uplink Sounding Reference Signal (UL SRS) for a cellular system, as follows:

(1) feedback mechanism for CoMP systems

The feedback mechanism of the CoMP system is divided into three ways: 1) explicit CSI feedback, i.e., the receiver can observe the channel without any transmit or receive processing; 2) ambiguous CSI feedback, i.e. a receiver can observe a Channel subjected to transmission processing or reception processing, such as Channel Quality Indicator (CQI), Precoding Matrix Indicator (PMI), and Rank Indicator (RI); 3) the UE transmits the SRS, that is, the BS estimates downlink channel state information (DLCSI) by using the SRS and utilizing reciprocity of uplink and downlink channels. See literature: 3GPP LTE technical report TR 36.814V.1.2.1, 3GPP TSG-RAN WG1#57bis, Los Angeles, CA USA, June 29-July 3, 2009. However, this document does not give a specific mechanism how the BS estimates the DL CSI through SRS and by exploiting reciprocity of uplink and downlink channels.

(2) SRS scheme for CoMP systems

Some companies propose to use SRS of LTE8.0 version in CoMP systems and to improve SRS performance with inter-cell cooperation. See literature: 3GPP LTE proposal R1-092776, CATT, Potevio, "Analysis of SRS scheme for CoMP", 3GPP TSG RAN WG1meeting #57bis, Los Angeles, USA, 29June-3July, 2009. However, the SRS proposed by the scheme is based on the SRS of different cells, and the SRS of different cells are not designed jointly, so that the mutual cooperation of the SRS among the cells of the CoMP system is not optimal.

(3) CSI statistical information based on channel reciprocity

Some proposals propose to estimate CSI statistics information of the downlink, such as a spatial channel covariance matrix, by using beam angle of arrival (DOA) information of the uplink. See literature: 3GPP LTE proposal R1-092737, Ericsson, ST-Ericsson, "On CSIfeedback for IMT-Advanced full filing CoMP schemes", 3GPP TSG RANWG 1meeting #57bis, Los Angeles, USA, 29June-3July, 2009. However, this method uses SRS of the same version as LTE8.0, and a special SRS method is not adopted for the CoMP system, and therefore, the SRS method cannot better embody the advantages of the CoMP system.

(4) Feedback capacity analysis based on different feedback methods

Some proposals consider that the feedback mechanism of LTE release 8.0 cannot support the higher feedback capacity required by LTE-a, and therefore, the following proposals propose a PUCCH (physical uplink control channel) -based feedback method, a PUSCH (physical uplink shared channel) -based feedback method, an SRS-based feedback method, and analyze the respective feedback capacities, and consider that a plurality of SC-FDMA symbols can be employed for transmission of an uplink SRS with respect to the SRS-based feedback method. See literature: 3GPP LTE proposal R1-092366, Huawei, "Feedback capacity analysis for differential Feedback mechanisms", 3GPP TSG RAN WG1 recording #57bis, Los Angeles, USA, 29June-3July, 2009. However, this proposal does not further give how to solve the SRS compatibility problem of LTE8.0 system and LTE-a system with multiple SC-FDMA symbols.

(5) Antenna verification for TDD CoMP system

The method estimates accurate CSI of a downlink by measuring SRS of the uplink and performing antenna verification on a TDD (time division multiplexing) CoMP system according to the measurement result. See literature: 3GPP LTE proposal R1-092659, Samsung, "Antenna california TDD CoMP", 3GPP TSG RAN WG1meeting #57bis, Los Angeles, USA, 29June-3July, 2009. However, the document does not provide a scheme for performing antenna calibration and estimating accurate CSI for an FDD (frequency division multiplexing) CoMP system by using SRS.

In view of the fact that the existing CSI acquisition methods based on SRS for LTE-a systems in the world are not comprehensive or specific, there is a need to find a comprehensive, efficient, simple and practical CSI acquisition method based on SRS, a base station and a user equipment, so as to be used in LTE-a systems and future fourth generation cellular mobile communication systems or other communication systems.

Disclosure of Invention

As described above, the 3GPP LTE-a has determined to support the CoMP technology and attempted to introduce the technology for acquiring CSI based on SRS and channel reciprocity, and the present invention aims to provide a CSI acquisition method based on SRS, a base station and a user equipment, in consideration of the deficiencies of the CSI feedback/acquisition technology and SRS design and detection method proposed by the prior art (for example, the proposals referred to in the above background section). Compared with the traditional method, the method and the system provided by the invention have the characteristics of comprehensiveness, high efficiency, simplicity and easiness in implementation.

According to a first aspect of the present invention, a method for acquiring channel state information is provided, which includes the following steps: detecting a Sounding Reference Signal (SRS) sent by user equipment; acquiring channel state information according to the detected SRS; performing joint resource scheduling with other base stations based on channel state information required by resource allocation; exchanging scheduling information after joint resource scheduling and/or data needing cooperative transmission with other base stations; performing transmission mode selection, power allocation and transmitter optimization with other base stations; and sending data and/or signaling to the user equipment.

Preferably, when the ue is a coordinated multi-point transmission/reception CoMP ue, the CoMP ue employs and transmits a CoMP-based SRS.

Preferably, the SRS detectable only by the LTE-a user equipment is placed in a subframe of the uplink of the CoMP user equipment using one or more symbols placed at the 7 th symbol and/or at the 13 th symbol of the subframe.

Preferably, the CoMP user equipment and the LTE-a non-CoMP user equipment multiplex the SRS in a code division multiplexing, CDM, manner.

Preferably, the SRS that the LTE-a user equipment can detect is used for all CoMP user equipments.

Preferably, the SRS transmitted by the user equipment is placed in a CoMP frequency band of an uplink of the serving base station and/or the cooperating base station.

Preferably, there is a one-to-one mapping relationship between the CoMP frequency bands of the uplink and the carrier frequency bands of the downlink of the serving base station and/or the cooperative base station.

Preferably, when the ue is a coordinated multi-point transmission/reception CoMP ue, both the serving base station and the coordinated base station detect an SRS sent by the CoMP ue.

Preferably, when the ue is a coordinated multi-point transmission/reception CoMP ue, both the serving base station and the coordinated base station acquire the channel state information according to the detected SRS sent by the CoMP ue.

Preferably, when a CoMP transmission mode is adopted, the serving base station and the cooperative base station exchange background information, where the background information includes at least one of the following information: the method comprises the steps of obtaining channel state information, dynamic configuration or semi-static configuration of the SRS, bandwidth of the SRS, sending period, sending duration, repetition times, sending power, located subframe, spectrum comb, cyclic shift of the sequence and sequence numbering.

Preferably, the channel state information required for resource allocation includes at least one of the following information:

-channel state characteristic information of downlink and/or uplink of user equipment of a serving base station and a serving cell,

-channel state characteristic information of the downlink and/or uplink of user equipments of the serving base station and the non-serving cell,

-channel state characteristic information of downlink and/or uplink of user equipment of a cooperating base station and serving cell, and

-channel state characteristic information of downlink and/or uplink of user equipments of cooperating base stations and non-serving cells.

According to a second aspect of the present invention, there is provided a base station, comprising: a transceiving unit for receiving data and/or signaling from a user equipment or a neighboring base station and transmitting the data and/or signaling to the user equipment; a Sounding Reference Signal (SRS) measuring unit for detecting an SRS signal sent by the user equipment from the transceiving unit; a channel state information acquisition unit which estimates or calculates channel state characteristic information based on the SRS signal from the SRS measurement unit; the cooperative mode judging unit is used for judging whether the user equipment enters a cooperative mode or not according to the acquired channel state characteristic information; the resource scheduling unit performs joint resource scheduling together with other base stations according to the channel state characteristic information exchanged with other base stations, and determines a data transmission mode and/or data needing cooperative transmission together with other base stations; and the power distribution and optimization unit is used for carrying out power distribution on the data needing cooperative transmission and carrying out transmitter optimization processing.

Preferably, the transceiver unit detects an SRS transmitted by the coordinated multipoint transmission/reception CoMP user equipment.

Preferably, the CoMP user equipment is CoMP user equipment located in a serving cell of the base station, or is CoMP user equipment located in a serving cell of a cooperative base station of the base station.

Preferably, the channel state characteristic information estimated or calculated by the channel state information processing unit includes at least one of the following information:

-channel state characteristic information of downlink and/or uplink of user equipment of a serving base station and a serving cell,

-channel state characteristic information of the downlink and/or uplink of user equipments of the serving base station and the non-serving cell,

-channel state characteristic information of downlink and/or uplink of user equipment of a cooperating base station and serving cell, and

-channel state characteristic information of downlink and/or uplink of user equipments of cooperating base stations and non-serving cells.

Preferably, the cooperation mode determination unit further determines whether the user equipment enters the cooperation mode according to the measured channel state information of the serving cell.

Preferably, the resource scheduling unit performs joint resource scheduling on the downlink resources.

Preferably, the resource scheduling unit performs joint resource scheduling on uplink resources, the transceiver unit sends the scheduling information to the user equipment, and the base station and the other base stations exchange the received data sent by the user equipment after the user equipment sends data to the base station and the other base stations respectively according to the scheduling information.

Preferably, the base station further includes: and the data processing unit is used for carrying out merging processing on the data which is received and exchanged and is sent by the user equipment.

According to a third aspect of the present invention, there is provided a user equipment, comprising: the receiving and transmitting unit receives data and/or signaling from the base station and transmits the data and/or signaling to the base station; a scheduling information obtaining unit that obtains cooperation information from the received data, the cooperation information including at least one of: the method comprises the steps that a service base station indicates information that user equipment enters a cooperation mode and scheduling information after joint resource scheduling of the service base station and a cooperation base station; the transmitter optimization unit is used for optimizing the transmitter of the uplink according to the cooperation information and respectively sending the optimized data to be sent to the serving base station and the cooperation base station through the transceiving unit; and a Sounding Reference Signal (SRS) transmitting unit for transmitting the SRS to the serving base station and the cooperative base station.

Preferably, when the user equipment is in a coordinated multi-point transmission/reception CoMP mode, the SRS transmission unit transmits the CoMP-based SRS to the serving base station and the coordinated base station.

Preferably, the user equipment further comprises: the data processing unit is used for merging the data from the service base station and/or the cooperative base station according to the scheduling information when the scheduling information acquisition unit acquires the information indicating that the user equipment enters the downlink cooperative mode from the service base station; and instructing a transmitter optimization unit to execute corresponding transmitter optimization processing when the scheduling information acquisition unit acquires the information that the serving base station instructs the user equipment to enter the uplink cooperation mode.

Preferably, the data processing unit is further configured to obtain communication environment information and feed back the communication environment information to the base station via the transceiver unit, where the communication environment information includes at least one of the following information: channel state characteristic information reflecting the channel state characteristics, and adjacent cell interference information.

According to a fourth aspect of the present invention, a method for acquiring channel state information is provided, which includes the following steps: detecting Sounding Reference Signals (SRS) sent by user equipment by a serving base station and a cooperative base station; the serving base station and the cooperative base station acquire channel state information according to the detected SRS; the service base station and the cooperative base station cooperatively perform joint resource scheduling based on channel state information required by resource allocation; the service base station and the cooperative base station exchange scheduling information after joint resource scheduling; the user equipment optimizes the transmitter according to the scheduling information after the joint resource scheduling sent by the service base station; and the user equipment sends data and/or signaling to the serving base station and/or the cooperative base station.

According to a specific embodiment of the present invention, a CSI acquisition method based on SRS is provided, which includes the following steps: for user equipment entering a CoMP mode in a serving cell, respectively detecting SRS information by a serving base station and a cooperative base station, wherein the SRS information at least comprises an SRS reflecting that the user equipment sends to the serving base station and an SRS sending to the cooperative base station by the user equipment, respectively estimating corresponding Channel State Information (CSI) by the serving base station and the cooperative base station according to the detected SRS information, exchanging the CSI by the serving base station and the cooperative base station, and then carrying out joint resource scheduling according to the exchanged CSI; and the service base station and the cooperative base station exchange scheduling information after joint resource scheduling, and perform cooperative data transmission according to the scheduling information.

According to another embodiment of the present invention, a base station for implementing the CSI acquisition method based on SRS includes a transceiver unit, an SRS measurement unit, a CSI acquisition unit, a data processing unit, a cooperation mode determination unit, a switch unit, a resource scheduling unit, and a power allocation and optimization unit. The transceiving unit receives and transmits data and signaling. The SRS measurement unit detects the SRS sent by the transceiver unit. And the CSI acquisition unit acquires the channel state information of the downlink channel and/or the uplink channel according to the SRS detected by the SRS measurement unit. The data processing unit processes the received data. The cooperation mode judging unit judges whether the user equipment enters a CoMP mode according to the channel state information sent by the CSI acquisition unit. The exchange unit is used for the multiple base stations to exchange background information with each other, and the exchange unit can use an X2 interface to exchange scheduling information after joint resource scheduling, CSI information acquired by different base stations, a cooperation mode of the multiple base stations, and the like. The resource scheduling unit is used for the base station to perform resource scheduling of the service area or joint resource scheduling among a plurality of base stations. The power distribution and optimization unit distributes power to the data to be transmitted and performs optimization processing on the transmitter (including adjusting the antenna angle, the number of antennas, the transmission power and the like of the transmitter).

According to still another embodiment of the present invention, a user equipment for implementing the CSI acquisition method based on SRS includes a transceiver unit, a data processing unit, a scheduling information acquisition unit, a transmitter optimization unit, and an SRS transmission unit. The transceiving unit receives and transmits data and signaling. The data processing unit processes the received data. The scheduling information acquisition unit acquires resource allocation information and cooperation information from the processed data. The transmitter optimization unit optimizes the uplink transmitter, including uplink transmission mode selection, power allocation, bit allocation, feedback mode selection, etc. The SRS sending unit sends an uplink SRS signal to the serving base station and the cooperative base station.

Therefore, the CSI acquisition method based on the SRS, the base station and the user equipment provided by the invention comprise the steps that the user equipment configures the SRS, sends the SRS, detects the SRS by the base station, acquires the CSI, schedules resources and the like, and have the advantages of high efficiency, wide application range, easiness in implementation and the like.

Drawings

The above features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a multi-base station cooperative network in accordance with the present invention;

fig. 2 shows a schematic diagram of SRS locations for LTE release 8.0 user equipment;

figure 3 shows a schematic diagram of the LTE-a downlink CoMP system feedback mechanism;

fig. 4 shows a schematic diagram of CSI acquisition based on SRS;

FIG. 5 shows a schematic of DOA measurement;

FIG. 6 shows a diagram of SRS sequences producing cross-correlation interference;

FIG. 7 shows a schematic diagram of a primary application scenario of the present invention;

fig. 8 is a schematic diagram illustrating a CSI acquisition method based on a cell SRS in a downlink CoMP-CB system according to a first embodiment of the present invention;

fig. 9 shows a flowchart of a CSI acquisition method based on a cell SRS in a downlink CoMP-CB system according to a first embodiment of the present invention;

fig. 10 is a diagram illustrating a CSI acquisition method for CoMP-based SRS in downlink CoMP-MU-MIMO according to a second embodiment of the present invention;

fig. 11 shows a flowchart of a CSI acquisition method for CoMP-based SRS in downlink CoMP-MU-MIMO according to a second embodiment of the present invention;

figure 12 shows a schematic diagram of a CoMP-based SRS design;

figure 13 shows a schematic diagram of a variant design of CoMP-based SRS;

figure 14 shows a schematic diagram of yet another variant design of CoMP-based SRS;

figure 15 shows a schematic diagram of division of CoMP frequency bands;

fig. 16 is a diagram illustrating an uplink and downlink symmetric band based on CoMP;

fig. 17 is a schematic diagram illustrating a CSI acquisition method for a CoMP Set-based SRS in uplink CoMP-MU-MIMO according to a third embodiment of the present invention;

fig. 18 is a flowchart illustrating a CSI acquisition method for a CoMP Set-based SRS in uplink CoMP-MU-MIMO according to a third embodiment of the present invention;

figure 19 shows a schematic diagram of yet another variant design of CoMP-based SRS;

fig. 20 is a diagram illustrating a CSI acquisition method for CoMP Set-based SRS in downlink CoMP-SU-MIMO according to a fourth embodiment of the present invention;

fig. 21 is a flowchart illustrating a CSI acquisition method for CoMP Set-based SRS in downlink CoMP-SU-MIMO according to a fourth embodiment of the present invention;

FIG. 22 shows a schematic diagram of a base station according to the present invention; and

fig. 23 shows a schematic diagram of a user equipment according to the present invention.

Detailed Description

In the following detailed description of the preferred embodiments of the present invention, reference is made to the accompanying drawings, in which details and functions that are not necessary for the invention are omitted so as not to obscure the understanding of the present invention. In order to clearly and specifically illustrate the implementation steps of the present invention, some specific embodiments of the present invention are given below, which are applicable to LTE cellular communication systems. It should be noted that the present invention is not limited to the application described in the embodiments, but is applicable to other wireless communication systems.

Fig. 1 shows a schematic diagram of a multi-base station cooperative network according to the present invention. Cellular systems divide a service coverage area into a plurality of contiguous radio coverage areas, i.e., cells. In fig. 1, the cells are schematically depicted as regular hexagons, and the entire service area is formed by the service cells of the base stations BS100 to BS103 being spliced. In the LTE system, a three-layer node network structure of a base station, a radio network control unit, and a core network is simplified into a two-layer node structure. Wherein the function of the radio network control unit is divided into base stations, the base stations coordinate and communicate with each other through a wired interface named "X2", as shown in fig. 1, the base stations BS100 to BS103 are connected to each other through an X2 interface, and background information is exchanged between the X2 interfaces through a central controller C-100, which is well known in the art. In fig. 1, the base stations BS100 to BS103 are schematically depicted as being located in a certain area of a cell and being equipped with omni-directional antennas. However, in the cell layout of a cellular communication system, the base stations BS100 to BS103 may be equipped with directional antennas, directionally covering a sub-area of the cell, which is usually called a sector. Thus, the representation of the multi-cell cellular communication system shown in fig. 1 is for illustrative purposes only and does not imply that the invention requires the specific conditions of the above limitations in the implementation of a cellular system. In fig. 1, a plurality of user equipments UE100 to UE108 are distributed in a cell in which BS100 to BS103 are located. Each of the user equipments UE100 to UE108 comprises a transmitter, a receiver, and a mobile terminal control unit, as is well known in the art. For any one user equipment, base stations are classified into two types, namely, serving base stations and non-serving base stations: a base station directly providing a communication service to a user equipment is referred to as a serving base station of the user equipment, and serving base stations such as UE100 and UE101 are BS 100; the other base stations are called non-serving base stations of the UE, and the non-serving base stations can be used as cooperative base stations of the serving base station to provide communication services for the user together, for example, the non-serving base stations of the UE100 and the UE101 are BS 101-BS 103. Since the LTE-a system decides to adopt the CoMP transmission scheme (see 3GPP standardized technical report 3GPP TR 36.814), two sets of CoMP transmission modes are represented in fig. 1: first, in the joint transmission mode, as shown in fig. 1, a BS100, a BS101, and a BS103 simultaneously transmit downlink data to a UE100, thereby improving the reception quality of a received signal at the UE100 end or the downlink data throughput; in the cooperative scheduling mode, the BS101, the BS102, and the BS103 perform resource scheduling in a coordinated manner, and then transmit downlink data to the UE104, the UE105, and the UE107 in their respective service areas, respectively, so as to achieve the purpose of Inter-Cell interference Cancellation/Coordination (ICIC). Therefore, in the LTE-a system, user equipments can be classified into two types, i.e., CoMP user equipments (CoMP UEs) and Non-CoMP user equipments (Non-CoMP UEs), according to whether to participate in CoMP transmission. In fig. 1, UEs 100, 104, 105, and 107 are CoMP UEs, and UEs 101, 102, 103, 106, and 108 are Non-CoMP UEs. Each CoMP UE has a serving base station and a cooperative base station, for example, the serving base station of UE100 is BS100, the cooperative base stations of UE100 are BS101 and BS103, the serving base station of UE104 is BS101, and the cooperative base stations of UE104 are BS102 and BS 103.

Fig. 2 shows a schematic diagram of SRS locations for LTE release 8.0 user equipment. In the LTE8.0 version, after long-term discussion of companies participating in standardization organization, it is determined that an SRS is placed in the last symbol of a subframe, the frequency domain interval of the SRS is two equivalent subcarriers, and the time-frequency structure of the SRS is shown in fig. 2.

Fig. 3 shows a schematic diagram of a feedback mechanism of an LTE-a downlink CoMP system. For the UE200, fig. 3 adopts a downlink CoMP transmission scheme based on single user MIMO (SU-MIMO), and the UE200 adopts an ambiguous CSI feedback mechanism, that is, the UE200 feeds back information such as CQI, PMI, RI processed by a receiver to the serving BS200 via an uplink in the serving cell, including CQI, PMI, RI of downlink from the serving BS200 to the UE200, CQI, PMI, RI of downlink from the cooperative base station BS201 to the UE200, and CQI, PMI, RI of downlink from the cooperative base station BS202 to the UE 200; for the user equipments UE201, U202, and UE203, fig. 3 adopts a downlink CoMP transmission scheme based on multi-user MIMO (MU-MIMO), and the UE202 adopts an explicit CSI feedback mechanism, that is, the UE202 feeds back CSI information to the serving base station BS201 through an uplink in the serving cell, such as downlink CSI from the serving base station BS201 to the UE202, CSI from the cooperative base station BS200 to the UE202 through a link, and CSI from the cooperative base station BS202 to the UE202 through a link, that is, H (BS201, BS200, BS 202). In addition, since the UE201, the UE202, and the UE203 are in the CoMP-MU-MIMO mode, the UE201, the UE202, and the UE203 need to know downlink CSI information of respective serving cells and CSI information of links through which respective neighboring cells interfere, so as to support switching between different CoMP modes or switching between CoMP and non-CoMP modes, thereby ensuring performance of the CoMP-MU-MIMO system, as described in reference R1-09xxxx (Qualcomm Europe, "CoMP email summary," 3GPP TSGRAN WG1meeting #57bis, Los Angeles, USA, 29June-3July, 2009): the CoMP transmission mode or the non-CoMP transmission mode is "transparent" for the user equipment, i.e. the user equipment does not need to know whether the user equipment is in the CoMP or non-CoMP mode; LTE-a should support handover between different CoMP modes or handover between CoMP and non-CoMP modes.

Fig. 4 shows a schematic diagram of CSI acquisition based on SRS. LTE-a supports the mechanism for UE to send SRS in TR 36.814v.1.2.1 technical report, i.e. BS estimates downlink channel state information (DL CSI) by detecting SRS and utilizing reciprocity of uplink and downlink channels. Especially in TDD systems, there is a significant reciprocity between the uplink and downlink channels, i.e. the uplink and downlink channel state information can be considered identical or similar and can be substituted for each other. Therefore, in a transmission mode based On CoMP-coded Beam-forming (CoMP-CB), a mechanism of UE sending SRS can be fully adopted, and the BS estimates or calculates downlink CSI according to the detected SRS, so as to greatly reduce or even cancel feedback overhead of uplink CSI, as in reference R1-092737(Ericsson, ST-Ericsson, "On CSI feedback for imt-Advanced full filtering CoMP schemes", 3GPP TSG RAN WG1 recording #57bis, Los Angeles, USA, 29 joint-3 j ary, 2009), which proposes to estimate CSI statistical information of downlink, such as a spatial channel covariance matrix, by using Beam angle of Arrival (DOA) information of uplink. Although the CSI acquisition method of reference R1-092737 can be theoretically and engineering implemented, it must be seen that the mechanism for acquiring CSI based on UE sending SRS has some obvious disadvantages: the transmitting antenna is preferably a Uniform Linear Array (ULA), so that the measured DOA is accurate; the measured CSI (e.g., the covariance of the channel) based on the DOA changes too slowly to instantaneously reflect the change of the channel, and thus, the CSI reflected by the CSI is a long-term statistically significant CSI; in the FDD system, the estimation error of the channel statistics of the uplink and downlink must be controlled within a certain range, so that the estimated CSI of statistical significance is accurate, and thus, the difficulty in implementing channel statistics estimation in the FDD system will increase.

Fig. 5 shows a schematic diagram of DOA measurement. The UE end 4 transmitting antennas and the BS end 8 receiving antennas all form a Uniform Linear Array (ULA) placement mode uniformly, the distance between the antennas is less than or equal to half of the carrier wavelength, the BS end can accurately measure DOA information of the SRS sent by the UE end, and the BS end can accurately estimate covariance information of spatial channels of a downlink according to DOA information of an uplink, which can be referred to reference R1-092737. The covariance matrix of the downlink channel at the BS end can be expressed as formula (1),

<math><mrow><mi>R</mi><mo>=</mo><munder><mo>&Integral;</mo><mi>&theta;</mi></munder><mi>p</mi><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow><mi>a</mi><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow><msup><mi>a</mi><mi>H</mi></msup><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow><mi>d&theta;</mi><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow></mrow></math>

where p (θ) is the ray power spectral density in the DOA direction θ and a (θ) is the antenna array response. For a ULA antenna array, since the antenna is isotropic, the antenna array response in the direction θ can be expressed as equation (2),

<math><mrow><mi>a</mi><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow><mo>=</mo><mfenced open='[' close=']'><mtable><mtr><mtd><mn>1</mn></mtd></mtr><mtr><mtd><msup><mi>e</mi><mrow><mo>-</mo><mi>j</mi><mn>2</mn><mi>&pi;</mi><mfrac><mi>d</mi><mi>&lambda;</mi></mfrac><mi>sin</mi><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow></mrow></msup></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><msup><mi>e</mi><mrow><mo>-</mo><mi>j</mi><mn>2</mn><mi>&pi;</mi><mfrac><mi>d</mi><mi>&lambda;</mi></mfrac><mrow><mo>(</mo><mi>N</mi><mo>-</mo><mn>1</mn><mo>)</mo></mrow><mi>sin</mi><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow></mrow></msup></mtd></mtr></mtable></mfenced><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></math>

where d ═ Δ X is the spacing between antennas, λ is the carrier wavelength, and N is the number of antennas. According to equation (2), then, the downlink and uplink antenna array responses can be expressed as equations (3) and (4), respectively,

<math><mrow><msub><mi>a</mi><mi>DL</mi></msub><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow><mo>=</mo><mfenced open='[' close=']'><mtable><mtr><mtd><mn>1</mn></mtd></mtr><mtr><mtd><msup><mi>e</mi><mrow><mo>-</mo><mi>j</mi><mn>2</mn><mi>&pi;&gamma;</mi><mfrac><msub><mi>f</mi><mi>DL</mi></msub><mrow><msub><mi>f</mi><mn>0</mn></msub><mi></mi></mrow></mfrac><mi>sin</mi><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow></mrow></msup></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><msup><mi>e</mi><mrow><mo>-</mo><mi>j</mi><mn>2</mn><mi>&pi;&gamma;</mi><mfrac><msub><mi>f</mi><mi>DL</mi></msub><mrow><msub><mi>f</mi><mn>0</mn></msub><mi></mi></mrow></mfrac><mrow><mo>(</mo><mi>N</mi><mo>-</mo><mn>1</mn><mo>)</mo></mrow><mi>sin</mi><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow></mrow></msup></mtd></mtr></mtable></mfenced><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></mrow></math>

<math><mrow><msub><mi>a</mi><mi>UL</mi></msub><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow><mo>=</mo><mfenced open='[' close=']'><mtable><mtr><mtd><mn>1</mn></mtd></mtr><mtr><mtd><msup><mi>e</mi><mrow><mo>-</mo><mi>j</mi><mn>2</mn><mi>&pi;&gamma;</mi><mfrac><msub><mi>f</mi><mi>UL</mi></msub><mrow><msub><mi>f</mi><mn>0</mn></msub><mi></mi></mrow></mfrac><mi>sin</mi><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow></mrow></msup></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><msup><mi>e</mi><mrow><mo>-</mo><mi>j</mi><mn>2</mn><mi>&pi;&gamma;</mi><mfrac><msub><mi>f</mi><mi>UL</mi></msub><mrow><msub><mi>f</mi><mn>0</mn></msub><mi></mi></mrow></mfrac><mrow><mo>(</mo><mi>N</mi><mo>-</mo><mn>1</mn><mo>)</mo></mrow><mi>sin</mi><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow></mrow></msup></mtd></mtr></mtable></mfenced><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>4</mn><mo>)</mo></mrow></mrow></math>

wherein f is_DLAnd f_ULRespectively upstream carrier frequency and downstream carrier frequency, f₀Is the center frequency, and γ in equations (3) and (4) is the downlink frequency f_DLAnd an uplink frequency f_ULThe corresponding wavelength. If the multiplexing distance is small, | f_DL-f_ULIf the value of | is small, then equation (5) and equation (6) can be obtained,

p_DL(θ)≈p_UL(θ)≈p(θ) (5)

R_DL≈R_UL (6)

if the multiplexing distance is large, | f_DL-f_ULIf | is large, then equations (7), (8), (9) can be obtained,

a_DL(θ)＝T(θ)a_UL(θ) (7)

<math><mrow><msub><mover><mi>R</mi><mo>^</mo></mover><mi>DL</mi></msub><mrow><mo>(</mo><mi>&theta;</mi><mo>)</mo></mrow><mo>=</mo><mi>T</mi><mrow><mo>(</mo><msub><mi>&theta;</mi><mi>Max</mi></msub><mo>)</mo></mrow><msub><mi>R</mi><mi>UL</mi></msub><msup><mi>T</mi><mi>H</mi></msup><mrow><mo>(</mo><msub><mi>&theta;</mi><mi>Max</mi></msub><mo>)</mo></mrow><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>9</mn><mo>)</mo></mrow></mrow></math>

here, the relationship between the downlink channel and the uplink channel can be obtained by the diagonal transmission matrix T (θ) as shown in equation (8). Therefore, as shown in equation (9), the covariance matrix of the uplink channel can be obtained, and the covariance matrix of the downlink channel can be obtained. Therefore, in consideration of the characteristics of the TDD system and the FDD system, equation (8) is more suitable for the TDD system, and equation (9) is more suitable for the FDD system.

Fig. 6 shows a schematic diagram of SRS sequence generation cross-correlation interference. In the downlink CoMP system, if the existing uplink SRS of LTE8.0 version is used, as shown in fig. 6, the UE400 sends the SRS based on the serving cell to the serving base station BS400, and the UE401, the UE402, and the UE403 send the SRS based on the serving cell to the serving base station BS401, then, because the sequence groups of different serving cells are different, the SRS sequences in the same sequence group have different lengths and different sequences in different sequence groups overlap, and cross-correlation interference is generated in the uplink SRS, as shown in formula (10).

<math><mrow><msub><mi>R</mi><mi>cross</mi></msub><mo>=</mo><mo>|</mo><mfrac><mn>1</mn><mi>N</mi></mfrac><munderover><mi>&Sigma;</mi><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><mi>N</mi></munderover><msub><mi>a</mi><mi>i</mi></msub><mo>&CenterDot;</mo><msub><mi>b</mi><mi>i</mi></msub><mo>|</mo><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>10</mn><mo>)</mo></mrow></mrow></math>

Wherein, { a₁，a₂，...，a_NAnd { b }and₁，b₂，...，b_NThe SRS sequences with the same length in fig. 6 but generating mutual interference. The cross-correlation interference may cause a decrease in the detection accuracy of the uplink SRS, and the decrease in the detection accuracy of the SRS may directly cause a decrease in the estimation accuracy of the downlink CSI, thereby indirectly causing a decrease in the performance of the scheduling algorithm and a decrease in the performance of CoMP. In the uplink CoMP system, since CSI of an uplink channel is directly obtained by detecting the uplink SRS1, there is also a problem that similar uplink SRS sequences may generate cross-correlation Interference, see reference R1-092367(Huawei, "Interference analysis on SRS for CoMP", 3GPP TSG RAN WG1 recording #57bis, Los Angeles, USA, 29June-3July, 2009).

Fig. 7 shows a schematic diagram of a main application scenario of the present invention. Considering that the SRS of LTE8.0 version is designed for a cell, that is, the base station of the cell does not need to detect the SRS sent by the user equipment of other cells, but the base station of multiple cells and the user equipment need to cooperate with each other due to the introduction of CoMP technology in the LTE-a system, the present invention tries to introduce the idea that multiple base stations and multiple user equipments cooperate with each other in the links of SRS design, detection, CSI estimation, etc. of the LTE-a system, and includes the following aspects:

firstly, a base station is defined to have the capability of detecting uplink SRS sent by CoMP UE of other cells, and the base station can estimate CSI from the base station to the CoMP UE by using the SRS;

secondly, independently and independently designing an uplink SRS based on a CoMP Set (CoMP Set) for the CoMP UE;

thirdly, it is proposed to differentiate CoMP-based SRS with LTE-a based SRS;

fourthly, specific symbols are proposed for designing the SRS based on the CoMP;

fifthly, it is proposed that the acquisition of CSI based on the SRS should be limited in a CoMP frequency band, and a fixed mapping relation should be adopted between a downlink CoMP frequency band and an uplink SRS frequency band so as to reduce the complexity of SRS detection.

[ first embodiment ] A method for manufacturing a semiconductor device

Fig. 8 is a diagram illustrating a CSI acquisition method based on a cell SRS in a downlink CoMP coordinated beamforming (CoMP-CB) transmission system according to a first embodiment of the present invention. As shown in fig. 8, base stations BS600, BS601, and BS602 are serving base stations of user equipment UE600, UE601, and UE602, respectively, base stations BS601 and BS602 are cooperative base stations of user equipment UE600, base stations BS600 and BS602 are cooperative base stations of user equipment UE601, base stations BS600 and BS601 are cooperative base stations of user equipment UE602, and three base stations BS600, BS601, and BS602 transmit data to three user equipment UE600, UE601, and UE602 through cooperation among beams, respectively, thereby forming a transmission scheme of downlink CoMP cooperative Beam-forming (CB) to achieve the purpose of improving data throughput at the edge of a radio Cell or suppressing co-channel Interference (ICI). As shown in fig. 8, in this embodiment, SRS information sent by three user equipments UE600, UE601, and UE602 can be detected not only by their respective serving base stations BS600, BS601, and BS602, but also by their respective cooperative base stations, and the serving base stations and the cooperative base stations estimate downlink CSI according to the detected SRS. Fig. 9 shows a flowchart of a CSI acquisition method based on a cell SRS in a downlink CoMP-CB system according to a first embodiment of the present invention, which describes implementation steps of the first embodiment in detail.

In step S100, the user equipment transmits an SRS to the serving base station;

the UE600, the UE601, and the UE602 respectively transmit uplink SRS to their respective serving base stations BS600, BS601, and BS602, and the uplink SRS transmitted by the UE600, the UE601, and the UE602 are independently designed for their respective serving cells, that is, the SRS of the UE600 is based on the cell where the BS600 is located, the SRS of the UE601 is based on the cell where the BS601 is located, and the SRS of the UE602 is based on the cell where the BS602 is located, as shown in formula (11),

<math><mrow><msubsup><mi>r</mi><mrow><mi>u</mi><mo>,</mo><mi>v</mi></mrow><mrow><mo>(</mo><mi>&alpha;</mi><mo>)</mo></mrow></msubsup><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>=</mo><msup><mi>e</mi><mi>j&alpha;n</mi></msup><msub><mover><mi>r</mi><mo>&OverBar;</mo></mover><mrow><mi>u</mi><mo>,</mo><mi>v</mi></mrow></msub><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>,</mo></mrow></math> <math><mrow><mn>0</mn><mo>&le;</mo><mi>n</mi><mo>&lt;</mo><msubsup><mi>M</mi><mi>sc</mi><mi>RS</mi></msubsup><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>11</mn><mo>)</mo></mrow></mrow></math>

wherein,

is the length of the reference signal sequence andsee 3GPP standardization report 3GPP TS 36.211. Multiple reference signal sequences are defined to be taken from a single base sequence, the multiple reference signal sequences being distinguished by different alpha's. The base sequences are divided into different groups, u ∈ {0, 1.., 29} is the group number, v is the number of base sequences in a group, see 3GPP standardization report 3GPP TS 36.211, inEach time slot n_sThe group number u may represent a group hopping pattern f_gh(n_s) And sequence shift pattern f_ss(n_s) As in equation (12),

u＝(f_gh(n_s)+f_ss(n_s))mod30 (12)

here, the group hopping pattern f_gh(n_s) And sequence shift pattern f_ss(n_s) Satisfying the formulas (13) and (14) respectively,

$f_{\mathrm{ss}}^{\mathrm{PUCCH}}=N_{\mathrm{ID}}^{\mathrm{cell}}\mathrm{mod}30---\left(14\right)$

in equation (13), the pseudo-random sequence c (i) may be initialized as in equation (15) in each radio frame,

$c_{\mathrm{init}}=f\left(N_{\mathrm{ID}}^{\mathrm{cell}}\right)---\left(15\right)$

in LTE release 8.0, the demodulation reference Signal (DM RS) and SRS for the uplink use the same set of base sequences, as shown in equation (16).

<math><mrow><msup><mi>r</mi><mi>SRS</mi></msup><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>=</mo><msubsup><mi>r</mi><mrow><mi>u</mi><mo>,</mo><mi>v</mi></mrow><mrow><mo>(</mo><mi>&alpha;</mi><mo>)</mo></mrow></msubsup><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>16</mn><mo>)</mo></mrow></mrow></math>

In step S101, a plurality of serving base stations each detect CSI of each cell;

the serving base station BS600 estimates CSI of downlink from the BS600 to the UE600 according to the SRS transmitted by the UE600, the serving base station BS601 estimates CSI of downlink from the BS601 to the UE601 according to the SRS transmitted by the UE601, and the serving base station BS602 estimates CSI of downlink from the BS602 to the UE602 according to the SRS transmitted by the UE 602.

In step S102, the serving base station determines whether the user equipment enters a CoMP mode;

the serving base station BS600 determines whether the UE600 enters the CoMP mode according to the estimated CSI of the downlink from the BS600 to the UE600, the serving base station BS601 determines whether the UE601 enters the CoMP mode according to the estimated CSI of the downlink from the BS601 to the UE601, and the serving base station BS602 determines whether the UE602 enters the CoMP mode according to the estimated CSI of the downlink from the BS602 to the UE 602. Whether the user equipment enters the cooperative mode and how to switch between the cooperative mode and the non-cooperative mode are quite complicated problems, and the embodiment only gives the judgment basis between the cooperative mode and the non-cooperative mode and an example of a switching method between the two modes. Assuming that the serving base station BS600, the cooperative base stations BS601, BS602 are in the same type of radio cell, the decision that the user equipment UE600 enters the cooperative mode is shown in equation (17),

CoMP_Mode＝f(α，β，γ，...) (17)

the decision formula for the user equipment to enter the cooperative mode is a function of a plurality of independent variables, wherein the threshold value of CQI is alpha, the threshold value of the interference of the adjacent cell is beta, and the long-term statistic SINR is gamma. The event triggering the user equipment to enter the cooperative mode from the non-cooperative mode comprises the following events: the combination of one or more events that the CQI value of the user equipment is less than alpha, the threshold value of the interference of the adjacent cell is more than beta, the long-term statistic SINR value gamma is less than the set threshold value, etc. The event triggering the user equipment to enter the non-cooperative mode from the cooperative mode comprises the following events: the combination of one or more events that the CQI value of the user equipment is larger than alpha, the threshold value of the interference of the adjacent cell is smaller than beta, the long-term statistic SINR value gamma is larger than the set threshold value, etc. And the service base station judges whether the user equipment enters the cooperative mode or not according to the measurement information, if the user equipment enters the cooperative mode, the service base station prepares to perform the operation of the next step in the cooperative mode, and if the user equipment does not enter the cooperative mode, the service base station still performs the operation of the non-cooperative mode.

In step S103, both the serving base station and the cooperative base station detect an SRS of the CoMP user equipment;

as mentioned above, an important innovation of the present invention is: it is defined that a base station has the capability of detecting uplink SRS transmitted by CoMP UE of other cells, and the base station can estimate CSI from the base station to the CoMP UE by using the SRS. For example, the UE600 enters the CoMP mode and the UE600 transmits the SRS to the serving base station BS600, but since the SRS is transmitted omnidirectionally, the cooperating base stations BS601 and BS602 may actually detect the SRS transmitted by the UE 600. However, considering that SRS is designed based on a serving cell in LTE8.0 release, and although the cooperative base stations BS601 and BS602 can detect SRS transmitted by the serving cell UE, neither the cooperative base stations BS601 and BS602 can detect the SRS, CSI from the cooperative base stations BS601 and BS602 to the UE600 cannot be estimated according to the SRS. In the embodiment of the present invention, the cooperative base stations BS601 and BS602 have the capability of detecting the SRS transmitted by the UE600, that is, the serving base station BS600 and the cooperative base stations BS601 and BS602 of the UE600, the serving base station BS601 and the cooperative base stations BS600 and BS602 of the UE601, and the serving base station BS602 and the cooperative base stations BS600 and BS601 of the UE602 communicate with each other in the background through the X2 interface. The background information includes: dynamic configuration or semi-static configuration of the SRS, bandwidth of the SRS, transmission period of the SRS, transmission duration, Repetition frequency (RPF), transmission power (for example, ratio of transmission power of the SRS and DM RS), located subframe, spectrum Comb (Comb), cyclic shift of a sequence, sequence number, and the like.

In step S104, the serving base station and the cooperative base station estimate CSI;

as shown in fig. 8, the serving base station BS600 and the cooperative base stations BS601, BS602 of the user equipment UE600 estimate CSI including CSI of downlink from the BS600 to the UE600, CSI of downlink from the BS601 to the UE600, and CSI of downlink from the BS602 to the UE600, from the respectively detected SRS. Similarly, the serving BS601 and the cooperative base stations BS600 and BS602 of the user equipment UE601 estimate CSI from the respectively detected SRS, where CSI includes CSI of downlink from the BS601 to the UE601, CSI of downlink from the BS600 to the UE601, and CSI of downlink from the BS602 to the UE 601. The serving base station BS602 and the cooperative base stations BS600, BS601 of the user equipment UE602 estimate CSI from the respectively detected SRS, the CSI including CSI of downlink from the BS602 to the UE602, CSI of downlink from the BS600 to the UE602, and CSI of downlink from the BS601 to the UE 602.

In step S105, background information is exchanged between the serving base station and the cooperative base station;

BS600, BS601, BS602 exchange background information. The background information includes CSI information estimated by each of the BS600, the BS601, and the BS 602.

In step S106, the serving base station and the cooperative base station perform joint resource scheduling;

the serving base station BS600 of the user equipment UE600, the serving base station BS601 of the UE601, and the serving base station BS602 of the UE602 perform joint resource scheduling according to the exchanged background information including the CSI information estimated by the BS600, the BS601, and the BS 602.

In step S107, the serving base station and the cooperative base station exchange scheduling information after joint resource scheduling;

in this embodiment, considering that the CoMP mode is a downlink CoMP-CB transmission mode, for three user equipments UE600, UE601, and UE602, three mutually cooperating serving base stations/cooperating base stations BS600, BS601, and BS602 exchange scheduling information after joint resource scheduling, where the CoMP-CB transmission mode does not require inter-base station exchange of data that needs to be cooperatively transmitted. The scheduling information after the joint scheduling includes identification numbers (IDs) of three serving/cooperative base stations BS600, BS601, and BS602 that cooperate with each other, data transmission modes of the BS600, BS601, and BS602, Resource Blocks (RBs) used by the BS600, BS601, and BS602, and the like.

In step S108, the serving base station and the cooperative base station perform transmission mode selection, power allocation, and transmitter optimization, respectively;

for the UE600, on one hand, the serving BS600 performs transmission mode selection, power allocation, and transmitter optimization according to the result of the joint resource scheduling; on the other hand, the cooperative base stations BS601 and BS602 perform transmission mode selection, power allocation and transmitter optimization according to the result after the joint resource scheduling. At this time, considering that the main purpose of the communication between the cooperative base stations BS601 and BS602 is to improve the data throughput and reduce ICI at the cell edge, the transmission mode of the serving base station BS600 and the transmission modes of the cooperative base stations BS601 and BS602 should have a certain relationship, which may generally have a multiplexing relationship, a diversity relationship, a multiplexing and diversity combining relationship, a joint coding relationship, and other combining relationships of data, the present embodiment is considered to adopt a cooperative beamforming (CoMP-CB) manner, that is, a cooperative beamforming mechanism is used to realize that three base stations BS600, BS601 and BS602 respectively transmit data to the user equipments UE601, UE602 and UE603 of their respective cells by using the Physical Downlink Shared Channel (PDSCH) in their respective cells, so as to achieve the purpose of improving the signal reception quality at the radio cell edge or improving the data throughput or suppressing ICI, therefore, the data transmitted in the present embodiment are not shared with each other.

In step S109, the serving base station and the cooperative base station send data and/or signaling to the user equipment;

in this example, due to the CoMP-CB transmission mode, for the UE600, the serving BS600 sends signaling and/or data to the UE600, and the cooperative BSs 601 and 602 only send signaling and/or data to the UE601 and the UE602, respectively; similarly, for the UE601, the serving BS601 sends signaling and/or data to the UE601, and the cooperative base stations BS600 and BS602 only send signaling and/or data to the UE600 and UE602, respectively; for the user equipment UE602, the serving base station BS602 sends signaling and/or data to the user equipment UE602, while the cooperative base stations BS600, BS601 only send signaling and/or data to the user equipment UE600 and UE601, respectively.

In step S110, the user equipment receives data and/or signaling transmitted by the serving base station.

In this example, due to the CoMP-CB transmission mode, the UE600 receives signaling and/or data sent by the serving BS600, the UE601 receives signaling and/or data sent by the serving BS601, and the UE602 receives signaling and/or data sent by the serving BS 602.

[ second embodiment ]

Fig. 10 shows a schematic diagram illustrating a CSI acquisition method for CoMP-based SRS in downlink CoMP-MU-MIMO according to a second embodiment of the present invention. As shown in fig. 10, base stations BS700, BS701, and BS702 are serving base stations of user equipment UE700, UE701, and UE702, respectively, base stations BS701 and BS702 are cooperative base stations of user equipment UE700, base stations BS700 and BS702 are cooperative base stations of user equipment UE701, base stations BS700 and BS701 are cooperative base stations of user equipment UE702, base stations BS700, BS701, and BS702 respectively employ 2, 1, and 1 transmit antennas, user equipment UE700, UE701, and UE702 respectively employ 2, 1, and 1 receive antennas, together forming a downlink 4 × 4 multi-user MIMO (MU-MIMO), and cooperatively transmit downlink data to three user equipment UE700, UE701, and UE702, thereby forming a transmission mode of downlink multi-user MIMO (CoMP-MU-MIMO), so as to achieve the purpose of improving data throughput at a wireless cell edge or suppressing ICI. In this embodiment, SRS information sent by three user equipments UE700, UE701, and UE702 can be detected not only by the respective serving base stations BS700, BS701, and BS702, but also by the respective cooperative base stations, and the serving base station and the cooperative base stations estimate downlink CSI according to the detected SRS. The SRS transmitted by the three user equipments UE700, UE701, and UE702 are designed based on the CoMP Set (CoMP Set), which is different from the SRS designed based on the serving cell in the first embodiment. Fig. 11 is a flowchart illustrating a CSI acquisition method for CoMP-based SRS in a downlink CoMP-MU-MIMO system according to a second embodiment of the present invention, which describes implementation steps of the second embodiment in detail.

In step S200, the user equipment transmits an SRS to the serving base station;

the user equipment UE700, UE701, and UE702 respectively transmit uplink SRS to their respective serving base stations BS700, BS701, and BS702, and the uplink SRS transmitted by the user equipment UE700, UE701, and UE702 are designed independently of each other, that is, the SRS of the UE700 is based on the cell where the BS700 is located, the SRS of the UE701 is based on the cell where the BS701 is located, and the SRS of the UE702 is based on the cell where the BS702 is located.

In step S201, a plurality of serving base stations each detect CSI of a respective serving cell;

the serving base station BS700 estimates CSI of downlink from the BS700 to the UE700 according to the SRS transmitted by the UE700, the serving base station BS701 estimates CSI of downlink from the BS701 to the UE701 according to the SRS transmitted by the UE701, and the serving base station BS702 estimates CSI of downlink from the BS702 to the UE702 according to the SRS transmitted by the UE 702.

In step S202, the serving base station determines whether the user equipment enters a CoMP mode;

the serving base station BS700 determines whether the UE700 enters the CoMP mode according to the estimated CSI of the downlink from the BS700 to the UE700, the serving base station BS701 determines whether the UE701 enters the CoMP mode according to the estimated CSI of the downlink from the BS701 to the UE701, and the serving base station BS702 determines whether the UE702 enters the CoMP mode according to the estimated CSI of the downlink from the BS702 to the UE 702. Similarly, the determination and switching method recited in the first embodiment of the present invention can be applied.

In step S203, both the serving base station and the cooperative base station detect an SRS of the CoMP user equipment;

as mentioned above, another important innovative point of the present invention is: for the CoMP UE, the uplink SRS based on the CoMP is independently and separately designed. For example, as shown in fig. 10, since the CoMP-MU-MIMO system includes three user equipments, namely UE700, UE701 and UE702, the three user equipments employing CoMP can employ a unified SRS design, that is, an SRS design based on a CoMP set. The LTE-A system divides all user equipment in a multi-base station service coverage area of the cellular system into CoMP user equipment (CoMP UE) and Non-CoMP user equipment (Non-CoMP UE) according to whether a CoMP transmission mode is adopted, the CoMP UE belongs to the LTE-A user equipment, and the Non-CoMP UE comprises LTE-A user equipment (LTE-A UE) and LTE8.0 version user equipment (LTE UE). As mentioned above, another important innovation of the present invention is: it is proposed to utilize LTE-a based SRS to distinguish CoMP based SRS. The present embodiment proposes: first, the SRS of LTE8.0 version is reserved, as in the 14 th symbol of the subframe structure in fig. 12; secondly, for an LTE-a system, which may adopt an uplink MIMO transmission manner to result in a rapid increase in the uplink SRS demand, the 14 th symbol in the LTE8.0 release may not meet the capacity demand of the LTE-a SRS, and therefore, the SRS of the LTE-a system must add a new symbol for placing the uplink SRS, as shown in fig. 12, the SRS of the LTE-a system is placed at the 7 th symbol and/or the 13 th symbol of the subframe structure (it should be noted that the 7 th symbol position and/or the 13 th symbol position are only used for exemplary purposes, and may also be placed at another one or more suitable symbol positions as needed); finally, the SRS of the CoMP UE is also in the newly added symbol, and the CoMP UE and the LTE-a non-CoMP UE are multiplexed by Code Division Multiplexing (CDM). In addition, the SRS based on CoMP may also adopt a modified design shown in fig. 13 or a modified design shown in fig. 14, and similarly, the SRS of the LTE-a system is placed at the 7 th symbol (fig. 14) or the 13 th symbol (fig. 13) of the subframe structure (it should be noted that the 7 th symbol position or the 13 th symbol position is only used for the purpose of example, and may also be placed at another suitable symbol position as required). As shown in fig. 10, the user equipment UE700 enters the CoMP mode and the UE700 transmits the SRS based on CoMP to the serving base station BS700, but since the SRS is transmitted in all directions, the cooperative base stations BS701 and BS702 may actually detect the SRS transmitted by the UE 700. In this embodiment, the present invention proposes that the cooperative base stations BS701 and BS702 have the capability of detecting the CoMP-based SRS transmitted by the UE700, that is, the serving base station BS700 and the cooperative base stations BS701 and BS702 of the UE700, the serving base station BS701 and the cooperative base stations BS700 and BS702 of the UE701, and the serving base station BS702 and the cooperative base stations BS700 and BS701 of the UE702 communicate with each other in the background through the X2 interface, so as to detect the CoMP-based uplink SRS. The SRS information in the background information comprises: dynamic configuration or semi-static configuration of the SRS, bandwidth of the SRS, transmission period of the SRS, transmission duration, Repetition frequency (RPF), transmission power (for example, ratio of transmission power of the SRS and DM RS), located subframe, spectrum Comb (Comb), cyclic shift of a sequence, sequence number, and the like. Wherein, if the SRS based on CoMP adopts dynamic configuration, it needs to be indicated by pdcch (physical downlink control channel), which has the characteristic of good real-time performance, but will increase the overhead of downlink signaling; if the SRS based on CoMP adopts semi-static configuration, it needs to be indicated by a higher layer signaling (e.g., RRC, Radio resource control), which has the characteristics of reliability and good scalability, and does not increase the signaling overhead of PDCCH, but the real-time performance is not very good. Considering that a future LTE-a system must have the capability of being backward compatible with an LTE8.0 (LTE) system, but the CoMP-based SRS proposed in this embodiment can only be sent by a CoMP UE, and a non-CoMP UE does not have the capability of sending the CoMP-based SRS, in the LTE-a system, a problem of how the non-CoMP UE handles the CoMP-based SRS must be considered, that is, a symbol resource occupied by the CoMP UE for sending the SRS is scheduled by a scheduler of a base station for the LTE8.0UE to send uplink data, so that the uplink SRS channel estimation performance of the CoMP UE is affected. For this problem, a simplest solution is that the LTE-a system divides CoMP UE and LTE8.0UE into different frequency bands, as shown in fig. 15, the CoMP UE only works in the CoMP frequency band, and the LTE8.0UE only works in the non-CoMP frequency band, i.e., Frequency Division Multiplexing (FDM), so that the base station does not receive SRS symbols sent by the CoMP UE and data symbols sent by LTE8.0UE at the same time in the same frequency band, and therefore, similar problems do not exist. In addition, in order to further reduce the implementation complexity of the CoMP transmission scheme and the complexity of design and detection of the CoMP-based SRS, and improve the accuracy of SRS detection, a method of fixed mapping between downlink carrier bands and uplink carrier bands may be adopted by using the characteristics of Multiple downlink carrier bands (Multiple DL carriers) and Multiple uplink carrier bands (Multiple UL carriers) of the LTE-a system, as shown in fig. 16.

In step S204, the serving base station and the cooperative base station estimate CSI;

as shown in fig. 10, the serving base station BS700 and the cooperative base stations BS701, BS702 of the user equipment UE700 estimate CSI including CSI of a downlink from the BS700 to the UE700, CSI of a downlink from the BS701 to the UE700, and CSI of a downlink from the BS702 to the UE700 from the separately detected SRS. Similarly, the serving BS701 and the cooperative base stations BS700 and BS702 of the user equipment UE701 estimate CSI according to the respectively detected SRS, where CSI includes CSI of downlink from the BS701 to the UE701, CSI of downlink from the BS700 to the UE701, and CSI of downlink from the BS702 to the UE 701. The serving base station BS702 and the cooperative base stations BS700, BS701 of the user equipment UE702 estimate CSI from the respectively detected SRS, the CSI including CSI of a downlink from the BS702 to the UE702, CSI of a downlink from the BS700 to the UE702, and CSI of a downlink from the BS701 to the UE 702.

In step S205, background information is exchanged between the serving base station and the cooperative base station;

BS700, BS701, BS702 exchange background information. The background information includes CSI information estimated by each of the BS700, the BS701, and the BS 702.

In step S206, the serving base station and the cooperative base station perform joint resource scheduling;

the serving base station BS700 of the UE700, the serving base station BS701 of the UE701, and the serving base station BS702 of the UE702 perform joint resource scheduling according to the exchanged background information including the CSI information estimated by the BS700, the BS701, and the BS 702.

In step S207, the serving base station and the cooperative base station exchange scheduling information after joint resource scheduling and/or data that needs cooperative transmission;

for the UE700, the serving BS700 and the cooperative base stations BS701 and BS702 exchange scheduling information after joint resource scheduling and/or data requiring cooperative transmission, where the scheduling information after joint scheduling includes identification numbers (IDs) of the serving BS700 and the cooperative base stations BS701 and BS702, a transmission mode of the data of the serving BS700 and the cooperative base stations BS701 and BS702, and a usage frequency band of the serving BS700 and the cooperative base stations BS701 and BS702, and the data requiring cooperative transmission refers to data requiring cooperative transmission, which is sent by the serving BS700 to the cooperative base stations BS701 and BS702 through background communication, and the data requiring cooperative transmission may adopt a multiplexing mode, a diversity mode, a joint coding mode, and other combination modes.

In step S208, the serving base station and the cooperative base station perform transmission mode selection, power allocation, and transmitter optimization, respectively;

the base stations BS700, BS701, and BS702 perform transmission mode selection, power allocation, and transmitter optimization according to the result after the joint resource scheduling. At this time, for the serving base station BS700, considering that the main purpose of the communication of the cooperative base stations BS701 and BS702 is to improve the data throughput at the cell edge and reduce the ICI, the transmission mode of the serving base station BS700 and the transmission modes of the cooperative base stations BS701 and BS702 should have a certain relationship, and may generally have a data multiplexing relationship, a diversity relationship, a multiplexing and diversity combining relationship, a joint coding relationship, and other combining relationships. Similarly, the transmission modes of the serving BS701 and the serving BS702 have similar association relationship. In consideration of the fact that the present embodiment adopts a CoMP-MU-MIMO mode, that is, three base stations, namely BS700, BS701 and BS702, respectively transmit data to the UE701, UE702 and UE703 by using a Physical Downlink Shared Channel (PDSCH) in each cell through a cooperative multi-user MIMO mechanism, so as to achieve the purpose of improving the signal reception quality at the edge of a wireless cell, or improving the data throughput, or suppressing ICI.

In step S209, the serving base station and the cooperative base station transmit data and/or signaling to the user equipment;

in this example, due to the CoMP-MU-MIMO transmission mode, for the UE700, not only the serving BS700 sends signaling and/or data to the UE700, but also the cooperative BSs 701 and 702 send signaling and/or data to the UE700 at the same time; similarly, for the UE701, not only the serving BS701 sends signaling and/or data to the UE701, but also the cooperative BS700 and BS702 simultaneously send signaling and/or data to the UE 701; for the user equipment UE702, not only the serving base station BS702 sends signaling and/or data to the user equipment UE702, but also the cooperative base stations BS700, BS701 simultaneously send signaling and/or data to the user equipment UE 702.

In step S210, the ue receives data and/or signaling transmitted by the serving base station and the cooperative base station.

The user equipment UE700 receives signaling and/or data sent by the serving base station BS700, the cooperative base stations BS701 and BS702, the user equipment UE701 receives signaling and/or data sent by the serving base station BS701, the cooperative base stations BS700 and BS702, and the user equipment UE702 receives signaling and/or data sent by the serving base station BS702, the cooperative base stations BS700 and BS 701.

[ third embodiment ]

Fig. 17 is a schematic diagram illustrating a CSI acquisition method for a CoMP Set-based SRS in uplink CoMP-MU-MIMO according to a third embodiment of the present invention. As shown in fig. 17, base stations BS800, BS801, and BS802 are serving base stations of user equipment UE800, UE801, and UE802, respectively, base stations BS801 and BS802 are cooperative base stations of user equipment UE800, base stations BS800 and BS802 are cooperative base stations of user equipment UE801, base stations BS800 and BS801 are cooperative base stations of user equipment UE802, user equipment UE800, UE801, and UE802 respectively employ 1, and 1 transmit antenna, base stations BS800, BS801, and BS802 respectively employ 1, and 1 receive antenna, together forming an uplink 3 × 3 multi-user MIMO (MU-MIMO), and cooperatively transmit uplink data to three base stations BS800, BS801, and BS802, thereby forming a transmission scheme of uplink multi-user MIMO (CoMP-MU-MIMO), so as to achieve the purpose of improving uplink data throughput at a wireless cell edge or suppressing uplink ICI. As shown in fig. 17, in this embodiment, SRS information transmitted by three user equipments UE800, UE801, and UE802 can be detected not only by their respective serving base stations BS800, BS801, and BS802, but also by their respective cooperative base stations, and the serving base stations and the cooperative base stations calculate uplink CSI according to the detected SRS. The SRS transmitted by the three user equipments UE800, UE801, and UE802 is designed based on a CoMP Set (CoMP Set). Fig. 18 is a flowchart illustrating a CSI acquisition method for SRS based on CoMP Set in an uplink CoMP-MU-MIMO system according to a third embodiment of the present invention, and details implementation steps of the third embodiment are described.

In step S300, the user equipment transmits an SRS to the serving base station;

the user equipment UE800, UE801, and UE802 respectively transmit uplink SRS to their respective serving base stations BS800, BS801, and BS802, and the uplink SRS transmitted by the user equipment UE800, UE801, and UE802 are independently designed, that is, the three uplink SRS of the user equipment UE800, UE801, and UE802 are designed based on the cell where the BS800, BS801, and BS802 are located.

In step S301, a plurality of serving base stations detect CSI of respective cells;

the serving base station BS800 estimates CSI of uplink from the UE800 to the BS800 according to the SRS transmitted by the UE800, the serving base station BS801 estimates CSI of uplink from the UE801 to the BS801 according to the SRS transmitted by the UE801, and the serving base station BS802 estimates CSI of uplink from the UE802 to the BS802 according to the SRS transmitted by the UE 802.

In step S302, the serving base station determines whether the user equipment enters a CoMP mode;

the serving base station BS800 determines whether the UE800 enters the uplink CoMP mode according to the estimated uplink CSI from the UE800 to the BS800, the serving base station BS801 determines whether the UE801 enters the uplink CoMP mode according to the estimated uplink CSI from the UE801 to the BS801, and the serving base station BS802 determines whether the UE802 enters the uplink CoMP mode according to the estimated uplink CSI from the UE802 to the BS 802.

In step S303, both the serving base station and the cooperative base station detect an SRS of the CoMP user equipment;

as shown in fig. 17, since the uplink CoMP-MU-MIMO system includes three user equipments, namely UE800, UE801 and UE802, the three user equipments using uplink CoMP may use a unified SRS design scheme, that is, an SRS design scheme based on an uplink CoMP set. As described above, the LTE-a system divides all the UEs in a coverage area of multiple base stations of the cellular system into CoMP UE (CoMP UE) and Non-CoMP UE (Non-CoMP UE) according to whether a CoMP transmission mode is adopted, where the CoMP UEs all belong to the LTE-a UE, and the Non-CoMP UE includes both LTE-a UE (LTE-a UE) and LTE8.0 version UE (LTE UE), and this division is also applicable to the uplink CoMP system. As mentioned above, another important innovative point of the present invention is: specific symbols are proposed for designing CoMP-based SRS. Therefore, the SRS of the LTE-a system must add a new symbol for placing the uplink SRS, as shown in fig. 19, this embodiment proposes: first, the SRS of LTE8.0 version is reserved, as in the 14 th symbol of the uplink subframe structure in fig. 2; secondly, for the problem that the LTE-a system may adopt an uplink MIMO transmission mode to result in a rapid increase of the uplink SRS demand, the 7 th symbol of the uplink subframe structure may be used to place the CoMP-based SRS, as shown in fig. 19 (it should be noted here that the 7 th symbol position is only used for the purpose of example, and may also be placed at another appropriate symbol position as needed); the SRS for the LTE-a non-CoMP UE may be placed in the 14 th symbol. As shown in fig. 17, the user equipment UE800 enters the CoMP mode, and the UE800 transmits the SRS based on CoMP to the serving base station BS800, but since the SRS is transmitted in all directions, the cooperative base stations BS801 and BS802 may actually detect the SRS transmitted by the UE 800. In the present embodiment, the present invention proposes that the cooperative base stations BS801 and BS802 have the capability of detecting CoMP-based SRS transmitted by the UE800, that is, the serving base station BS800 and the cooperative base stations BS801 and BS802 of the UE800, the serving base station BS801 and the cooperative base stations BS800 and BS802 of the UE801, and the serving base station BS802 and the cooperative base stations BS800 and BS801 of the UE802, and these three base stations (both serving base stations and cooperative base stations) perform background communication with each other through an X2 interface to detect CoMP-based uplink SRS.

In step S304, the serving base station and the cooperative base station estimate CSI;

as shown in fig. 17, the serving base station BS800 and the cooperative base stations BS801, BS802 of the user equipment UE800 estimate CSI including CSI of uplink of the UE800 to the BS800, CSI of uplink of the UE800 to the BS801, and CSI of uplink of the UE800 to the BS802 from the separately detected SRS. Similarly, the serving base station BS801 and the cooperative base stations BS800 and BS802 of the user equipment UE801 estimate CSI including uplink CSI of the UE801 to the BS801, downlink CSI of the UE801 to the BS800, and uplink CSI of the UE801 to the BS802 from the respectively detected SRS. The serving base station BS802 and the cooperative base stations BS800, BS801 of the user equipment UE802 estimate CSI including CSI of uplink from the UE802 to the BS802, CSI of uplink from the UE802 to the BS800, and CSI of uplink from the UE802 to the BS800, from the SRS detected respectively.

In step S305, the serving base station and the cooperative base station exchange background information;

the BS800, BS801, BS802 exchange background information. The background information includes CSI information estimated by each of the BS800, the BS801, and the BS 802. The SRS information in the background information comprises: dynamic configuration or semi-static configuration of the SRS, bandwidth of the SRS, transmission period of the SRS, transmission duration, Repetition frequency (RPF), transmission power (for example, ratio of transmission power of the SRS and DM RS), located subframe, spectrum Comb (Comb), cyclic shift of a sequence, sequence number, and the like.

In step S306, the serving base station and the cooperative base station perform joint resource scheduling;

the serving base station BS800 of the user equipment UE800, the serving base station BS801 of the UE801, and the serving base station BS802 of the UE802 perform joint resource scheduling according to background information obtained by exchange and including uplink CSI information estimated by the BS800, the BS801, and the BS802, respectively.

In step S307, the serving base station and the cooperative base station exchange scheduling information after joint resource scheduling;

for the user equipment UE800, the serving base station BS800 and the cooperative base stations BS801 and BS802 exchange scheduling information after joint resource scheduling, where the scheduling information after joint scheduling includes identification numbers (IDs) of the serving base station BS800 and the cooperative base stations BS801 and BS802, transmission modes of data of the serving base station BS800 and the cooperative base stations BS801 and BS802, uplink use frequency bands of the serving base station BS800 and the cooperative base stations BS801 and BS802, and the like.

In step S308, the user equipment performs transmitter optimization;

the user equipment UE800, UE801, and UE802 perform transmitter optimization according to scheduling information sent by the serving base stations BS800, BS801, and BS802, respectively, where the transmitter optimization includes uplink power allocation, uplink power control, and the like, thereby achieving the purpose of improving data throughput of the uplink in the wireless cell or suppressing ICI. In consideration of the fact that the present embodiment adopts a coordinated multi-user MIMO (CoMP-MU-MIMO) scheme, data transmission in the present embodiment is not shared with each other.

In step S309, the ue sends data and/or signaling to the serving base station and/or the cooperative base station;

in this example, since the uplink CoMP-MU-MIMO transmission mode is adopted, for the UE800, the UE800 sends signaling and/or data to the serving BS800 and/or the cooperative base stations BS801 and BS802, for example, both the BS801 and the BS802 may detect the CoMP-based SRS sent by the UE 800; similarly, for the UE801, the UE801 sends signaling and/or data to the serving BS801 and/or the cooperative base stations BS800 and BS802, for example, both the BS800 and BS802 may detect the CoMP-based SRS sent by the UE 801; for the user equipment UE802, the user equipment UE802 sends signaling and/or data to the serving base station BS802 and/or the cooperative base stations BS800, BS801, e.g., both BS800 and BS801 may detect the CoMP-based SRS sent by the UE 802.

In step S310, the base station receives data and/or signaling sent by the user equipment.

Since the embodiment adopts the uplink CoMP-MU-MIMO transmission mode, the base station BS800 receives data and/or signaling sent by the user equipment UE800, UE801, and UE802, the base station BS801 receives data and/or signaling sent by the user equipment UE800, UE801, and UE802, and the base station BS802 receives data and/or signaling sent by the user equipment UE800, UE801, and UE 802.

[ fourth example ] A

Fig. 20 is a diagram illustrating a CSI acquisition method for CoMP Set-based SRS in downlink CoMP-SU-MIMO according to a fourth embodiment of the present invention. As shown in fig. 20, the base station BS900 is a serving base station of the user equipment UE900, the base stations BS901 and BS902 are cooperative base stations of the user equipment UE900, the base stations BS900, BS901 and BS902 respectively employ 2, 1 and 1 transmit antennas, the user equipment UE900 employs 4 receive antennas, and together form a downlink 4 × 4 single-user MIMO (SU-MIMO) system, and the serving base station BS900, the cooperative base stations BS901 and BS902 cooperate to transmit downlink data to the user equipment UE900, thereby forming a downlink CoMP single-user 0 (MIM-SU-MIMO) transmission scheme, so as to achieve the purpose of improving data throughput at the edge of a wireless cell or suppressing ICI. As shown in fig. 20, in this embodiment, the SRS information sent by the user equipment UE900 can be detected not only by the serving base station BS900 but also by the respective cooperative base stations BS901 and BS902, and the serving base station BS900 and the cooperative base stations BS901 and BS902 estimate the downlink CSI according to the detected SRS. Further, the SRS transmitted by the user equipment UE900 is designed based on the CoMP Set (CoMP Set), which is different from the SRS designed based on the serving cell in the first embodiment. Fig. 21 is a flowchart illustrating a CSI acquisition method for SRS based on CoMP Set in a downlink CoMP-SU-MIMO system according to a fourth embodiment of the present invention, which describes implementation steps of the fourth embodiment in detail.

In step S400, the user equipment transmits an SRS to the serving base station;

the UE900 sends an uplink SRS to the serving BS900, where the SRS of the UE900 is based on a cell where the BS900 is located.

In step S401, the serving base station detects CSI of the serving cell;

the serving base station BS900 estimates the CSI of the downlink from the BS900 to the UE900 from the SRS transmitted by the UE 900.

In step S402, the serving base station determines whether the user equipment enters a CoMP mode;

the serving base station BS900 determines whether the UE900 enters the CoMP mode according to the estimated CSI of the downlink from the BS900 to the UE 900.

In step S403, both the serving base station and the cooperative base station detect an SRS of the CoMP user equipment;

as mentioned above, another important innovative point of the present invention is: for the CoMP UE, an uplink SRS based on the CoMP Set is independently and separately designed. For example, as shown in fig. 20, since the CoMP-SU-MIMO system includes three base stations, that is, BS900, BS901 and BS902, the three base stations using CoMP can adopt a unified SRS design scheme, that is, an SRS design scheme based on a CoMP set. As shown in fig. 20, the user equipment UE900 enters the CoMP mode, and the UE900 transmits the SRS based on the CoMP Set to the serving base station BS900, but since the SRS is transmitted in all directions, the cooperative base stations BS901 and BS902 can actually detect the SRS transmitted by the UE 900. In this embodiment, the cooperative base stations BS901 and BS902 have the capability of detecting the SRS based on the CoMP Set transmitted by the UE900, that is, the serving base station BS900 of the UE900 and the cooperative base stations BS901 and BS902 can respectively detect the uplink SRS based on the CoMP Set.

In step S404, the serving base station and the cooperative base station estimate CSI;

as shown in fig. 20, the serving base station BS900 and the cooperative base stations BS901 and BS902 of the user equipment UE900 estimate CSI including CSI of downlink from the BS900 to the UE900, CSI of downlink from the BS901 to the UE900, and CSI of downlink from the BS902 to the UE900, from the separately detected SRS.

In step S405, background information is exchanged between the serving base station and the cooperative base station;

the BS900, BS901, BS902 exchange background information. The background information includes CSI information estimated by each of the BS900, BS901, and BS902, and these background information are exchanged through the X2 interface. The SRS information in the background information comprises: dynamic configuration or semi-static configuration of the SRS, bandwidth of the SRS, transmission period of the SRS, transmission duration, Repetition frequency (RPF), transmission power (for example, ratio of transmission power of the SRS and DM RS), located subframe, spectrum Comb (Comb), cyclic shift of a sequence, sequence number, and the like.

In step S406, the serving base station and the cooperative base station perform joint resource scheduling;

the serving BS900 of the UE900 and the cooperative base stations BS901 and BS902 of the UE900 perform joint resource scheduling according to the exchanged background information including the CSI information estimated by the BS900, BS901 and BS 902.

In step S407, the serving base station and the cooperative base station exchange scheduling information after joint resource scheduling and/or data that needs cooperative transmission;

the serving base station BS900 and the cooperative base stations BS901 and BS902 exchange scheduling information after joint resource scheduling and/or data needing cooperative transmission, where the scheduling information after joint scheduling includes identification numbers (IDs) of the serving base station BS900 and the cooperative base stations BS901 and BS902, a transmission mode of the data of the serving base station BS900 and the cooperative base stations BS901 and BS902, and a use frequency band of the serving base station BS900 and the cooperative base stations BS901 and BS902, and the data needing cooperative transmission refers to data needing cooperative transmission sent by the serving base station BS900 to the cooperative base stations BS901 and BS902 through background communication, and the data needing cooperative transmission may adopt a multiplexing mode, a diversity mode, a joint coding mode and other combination modes.

In step S408, the serving base station and the cooperative base station perform transmission mode selection, power allocation, and transmitter optimization, respectively;

on one hand, the serving BS900 performs transmission mode selection, power allocation, and transmitter optimization according to the result after the joint resource scheduling; on the other hand, the cooperative base stations BS901 and BS902 perform transmission mode selection, power allocation and transmitter optimization according to the result after the joint resource scheduling. At this time, considering that the main purpose of the cooperative base stations BS901, BS902 communication is to improve the data throughput at the cell edge and reduce ICI, therefore, the transmission mode of the serving BS900 and the transmission modes of the cooperative base stations BS901 and BS902 should have a certain relationship, and may generally have a multiplexing relationship of data, a diversity relationship, a multiplexing and diversity combining relationship, a joint coding relationship and other combining relationships, considering that the present embodiment adopts a cooperative single-user MIMO (CoMP-SU-MIMO) manner, that is, the three base stations BS900, BS901 and BS902 are implemented by a single-user MIMO mechanism to respectively transmit data to the UE900 by using a Physical Downlink Shared Channel (PDSCH) in each cell, therefore, the purpose of improving the signal receiving quality of the wireless cell edge or improving the data throughput or suppressing ICI is achieved, and therefore, the data transmitted in the embodiment are not shared with each other.

In step S409, the serving base station and the cooperative base station send data and/or signaling to the user equipment;

in this example, due to the CoMP-SU-MIMO transmission mode, the serving BS900, the cooperating base stations BS901, BS902 all send signaling and/or data to the user equipment UE 900.

In step S410, the user equipment receives data and/or signaling transmitted by the serving base station and the cooperative base station.

The user equipment UE900 receives data and/or signaling sent by the serving base station BS900 and the cooperating base stations BS901, BS 902.

[ hardware implementation ]

Fig. 22 shows a schematic diagram of a base station for acquiring CSI based on SRS according to the present invention.

As shown in fig. 22, the base station of the present invention includes a transceiver unit 21, an SRS measurement unit 22, a CSI acquisition unit 23, a data processing unit 24, a cooperation mode determination unit 25, a switch unit 26, a resource scheduling unit 27, and a power allocation and optimization unit 28.

The base station according to this embodiment can implement the functions of the serving base station and the cooperative base station of the present invention, and for avoiding redundancy, only the example is described here, and specific operation flows can refer to the above embodiments. Alternatively, the above-described unit structures may be combined to form a single or other unit structure.

The transceiving unit 21 receives data and/or signaling from the user equipment or the neighboring base station and transmits the data and/or signaling to the user equipment.

The SRS measurement section 22 detects the SRS signal from the transmission/reception section 21;

CSI acquisition section 23 estimates or calculates channel state characteristic information (e.g., CQI, CSI, etc.) from the SRS signal from SRS measurement section 22.

The data processing unit 24 performs down-conversion, sampling, channel estimation, data detection, data demodulation, data combination, and the like on the received data.

The cooperation mode judgment unit 25 judges whether the user equipment enters the cooperation mode according to the obtained channel state characteristic information. Here, it should be noted that there are various ways to determine whether to enter the cooperative mode as described in the previous embodiments, and the determination may not be made based on the channel state characteristic information. In addition, the cooperation mode determination unit 25 may be omitted by entering the cooperation mode directly in response to a request from the user equipment.

The exchanging unit 26 further exchanges scheduling information after resource scheduling with the cooperative cell. In the downlink cooperative communication, the switching unit 26 will also switch data that needs to be cooperatively transmitted to the user equipment.

The resource scheduling unit 27 performs unified joint resource scheduling (including uplink and/or downlink resource allocation) together with the cooperative base station according to the exchanged channel state characteristic information. In the downlink cooperative communication, the data transmission mode of each base station and/or the data needing cooperative transmission are further determined.

The power allocation and optimization unit 28 performs power allocation on data to be transmitted cooperatively, and after performing transmitter optimization (including adjustment on the antenna angle, the number of antennas, the transmission power, and the like of the transmitter), the data is transmitted to the user equipment by the transceiver unit 21.

It should be noted that, in the uplink cooperative communication, after the transceiver unit 21 transmits the scheduling information to the user equipment, the user equipment transmits data to the serving base station and the cooperative base station according to the uplink resource information after scheduling. After that, the switching unit 26 exchanges the uplink data transmitted by the user equipment with the cooperative base station, and the data processing unit 24 performs combining processing, thereby implementing uplink data cooperative communication.

Fig. 23 shows a schematic diagram of a user equipment according to the present invention.

For avoiding redundancy, only the structure of the ue is illustrated here, and the specific operation flow may refer to the above embodiments.

As shown in fig. 23, the user equipment according to the present invention includes a transceiving unit 31, a data processing unit 32, a scheduling information acquiring unit 33, a transmitter optimizing unit 34, and an SRS transmitting unit 35.

The transceiver unit 31 receives data signaling from the base station and transmits data and/or signaling to the base station.

The data processing unit 32 processes the received data, and the processing includes down conversion, sampling, channel estimation, data detection, data combination, and the like. Here, the data processing unit 32 may have a communication environment information acquisition function, may further acquire and feed back communication environment information to the base station via the transceiver unit 31, the communication environment information including at least one of the following information: channel state characteristic information reflecting the channel state characteristics, and adjacent cell interference information.

The scheduling information obtaining unit 33 obtains the cooperation information from the processed data, including the information that the serving base station instructs the ue to enter the cooperation mode, and the scheduling information after the serving base station and the cooperative base station perform joint resource scheduling. Under the condition that the scheduling information includes an instruction for the user equipment to enter a downlink cooperation mode, after the serving base station and the cooperative base station cooperate to perform downlink data transmission, the data processing unit 32 performs merging processing on data from the serving base station and the cooperative base station according to the scheduling information from the serving base station; in case the cooperation information includes an indication to the user equipment to enter the uplink cooperation mode, the corresponding processing is performed by the transmitter optimization unit 34.

The transmitter optimization unit 34 optimizes the uplink transmitter according to the cooperation information, including uplink transmission mode selection, power allocation, bit allocation, feedback mode selection, and the like, and transmits the optimized data to be transmitted to the serving base station and the cooperative base station via the transceiver unit 31, respectively.

The SRS transmission unit 35 transmits an uplink SRS signal to the serving base station and the cooperative base station.

As described above, the embodiment of the present invention provides a method, a base station, and a user equipment for acquiring SRS-based channel state information, and has the characteristics of simple design, comprehensiveness, high efficiency, and flexibility. Therefore, the method, the base station and the user equipment for acquiring the channel state information based on the SRS in the technical field of wireless transmission according to the present invention can provide an important theoretical basis and a specific implementation method for Network cooperation problems of various wireless or mobile networks including a third generation cellular mobile Network (3G), an ultra-third generation cellular mobile Network (S3G, B3G), a fourth generation cellular mobile Network (4G), a single frequency broadcast Network (SFN), a Wireless Local Area Network (WLAN), a Wireless Wide Area Network (WWAN), a multimedia broadcast multicast service Network (MBMS), an Ad Hoc Network (Mesh, Ad Hoc, cellular Network), and a digital Home Network (e-Home).

In the above description, a plurality of examples are listed for each step, and although the inventors mark examples associated with each other as much as possible, this does not mean that these examples necessarily have correspondence relationships according to the corresponding reference numerals. As long as there is no contradiction between the conditions given by the selected examples, examples having reference numbers that do not correspond to each other may be selected in different steps to constitute corresponding technical solutions, and such technical solutions should also be considered to be included in the scope of the present invention.

It should be noted that in the above description, the technical solutions of the present invention are shown by way of example only, and the present invention is not meant to be limited to the above steps and unit structures. Steps and cell structures may be adjusted and chosen as desired, where possible. Accordingly, certain steps and elements are not essential elements for implementing the general inventive concept of the present invention. Therefore, the technical features necessary for the present invention are only limited by the minimum requirements capable of implementing the general inventive concept of the present invention, and are not limited by the above specific examples.

The invention has thus been described with reference to the preferred embodiments. It should be understood by those skilled in the art that various other changes, substitutions, and additions may be made without departing from the spirit and scope of the invention. The scope of the invention is therefore not limited to the particular embodiments described above, but rather should be determined by the claims that follow.

Claims (24)

1. A channel state information acquisition method comprises the following steps:

detecting a Sounding Reference Signal (SRS) sent by user equipment;

acquiring channel state information according to the detected SRS;

performing joint resource scheduling with other base stations based on channel state information required by resource allocation;

exchanging scheduling information after joint resource scheduling and/or data needing cooperative transmission with other base stations;

performing transmission mode selection, power allocation and transmitter optimization with other base stations; and

and sending data and/or signaling to the user equipment.

2. The channel state information acquisition method of claim 1, wherein

When the user equipment is coordinated multi-point transmission/reception CoMP user equipment, the CoMP user equipment adopts and sends the SRS based on CoMP.

3. The channel state information acquisition method according to claim 2, wherein

Placing the SRS detectable only by the LTE-A user equipment in a subframe of an uplink of the CoMP user equipment with one or more symbols placed at the 7 th symbol and/or the 13 th symbol of the subframe.

4. The channel state information acquisition method according to claim 3, wherein

The CoMP user equipment and the LTE-a non-CoMP user equipment multiplex the SRS in a code division multiplexing, CDM, manner.

5. The channel state information acquisition method according to claim 3, wherein

The SRS that the LTE-a user equipment can detect is used for all CoMP user equipments.

6. The channel state information acquisition method of claim 1, wherein

The SRS transmitted by the user equipment is placed in a CoMP frequency band of an uplink of a serving base station and/or a cooperating base station.

7. The channel state information acquisition method according to claim 6, wherein

The CoMP frequency bands of the uplink and the carrier frequency bands of the downlink of the serving base station and/or the cooperative base station have a one-to-one mapping relationship.

8. The channel state information acquisition method of claim 1, wherein

When the user equipment is coordinated multi-point transmission/reception CoMP user equipment, the serving base station and the coordinated base station detect SRS sent by the CoMP user equipment.

9. The channel state information acquisition method of claim 1, wherein

When the user equipment is coordinated multi-point transmission/reception CoMP user equipment, the serving base station and the coordinated base station acquire channel state information according to the detected SRS sent by the CoMP user equipment.

10. The channel state information acquisition method of claim 1, wherein

When a CoMP transmission mode is adopted, the serving base station and the cooperative base station exchange background information, wherein the background information includes at least one of the following information: the method comprises the steps of obtaining channel state information, dynamic configuration or semi-static configuration of the SRS, bandwidth of the SRS, sending period, sending duration, repetition times, sending power, located subframe, spectrum comb, cyclic shift of the sequence and sequence numbering.

11. The channel state information acquisition method of claim 10, wherein the channel state information acquisition method is characterized in that

The channel state information required for resource allocation includes at least one of the following information:

-channel state characteristic information of downlink and/or uplink of user equipment of a serving base station and a serving cell,

-channel state characteristic information of the downlink and/or uplink of user equipments of the serving base station and the non-serving cell,

-channel state characteristic information of downlink and/or uplink of user equipment of a cooperating base station and serving cell, and

-channel state characteristic information of downlink and/or uplink of user equipments of cooperating base stations and non-serving cells.

12. A base station, comprising:

a transceiving unit for receiving data and/or signaling from a user equipment or a neighboring base station and transmitting the data and/or signaling to the user equipment;

a Sounding Reference Signal (SRS) measuring unit for detecting an SRS signal sent by the user equipment from the transceiving unit;

a channel state information acquisition unit which estimates or calculates channel state characteristic information based on the SRS signal from the SRS measurement unit;

the cooperative mode judging unit is used for judging whether the user equipment enters a cooperative mode or not according to the acquired channel state characteristic information;

the resource scheduling unit performs joint resource scheduling together with other base stations according to the channel state characteristic information exchanged with other base stations, and determines a data transmission mode and/or data needing cooperative transmission together with other base stations; and

and the power distribution and optimization unit is used for carrying out power distribution on the data needing cooperative transmission and carrying out transmitter optimization processing.

13. Base station according to claim 12, characterized in that

The receiving and transmitting unit detects an SRS sent by the coordinated multi-point transmission/reception CoMP user equipment.

14. Base station according to claim 13, characterized in that

The CoMP user equipment is CoMP user equipment located in a serving cell of the base station, or is CoMP user equipment located in a serving cell of a cooperative base station of the base station.

15. Base station according to claim 12, characterized in that

The channel state characteristic information estimated or calculated by the channel state information processing unit includes at least one of the following information:

-channel state characteristic information of downlink and/or uplink of user equipment of a serving base station and a serving cell,

-channel state characteristic information of the downlink and/or uplink of user equipments of the serving base station and the non-serving cell,

-channel state characteristic information of downlink and/or uplink of user equipment of a cooperating base station and serving cell, and

-channel state characteristic information of downlink and/or uplink of user equipments of cooperating base stations and non-serving cells.

16. Base station according to claim 12, characterized in that

The cooperation mode judging unit also judges whether the user equipment enters the cooperation mode according to the measured channel state information of the service cell.

17. Base station according to claim 12, characterized in that

And the resource scheduling unit performs joint resource scheduling on the downlink resources.

18. Base station according to claim 12, characterized in that

The resource scheduling unit performs joint resource scheduling on uplink resources, an

The transceiving unit transmits the scheduling information to the user equipment,

and after the user equipment respectively sends data to the base station and the other base stations according to the scheduling information, the base station and the other base stations exchange the received data sent by the user equipment.

19. The base station of claim 18, further comprising:

and the data processing unit is used for carrying out merging processing on the data which is received and exchanged and is sent by the user equipment.

20. A user equipment, comprising:

the receiving and transmitting unit receives data and/or signaling from the base station and transmits the data and/or signaling to the base station;

a scheduling information obtaining unit that obtains cooperation information from the received data, the cooperation information including at least one of: the method comprises the steps that a service base station indicates information that user equipment enters a cooperation mode and scheduling information after joint resource scheduling of the service base station and a cooperation base station;

the transmitter optimization unit is used for optimizing the transmitter of the uplink according to the cooperation information and respectively sending the optimized data to be sent to the serving base station and the cooperation base station through the transceiving unit; and

and a Sounding Reference Signal (SRS) transmitting unit for transmitting the SRS to the serving base station and the cooperative base station.

21. The UE of claim 20, wherein the UE is configured to perform the following steps

When the user equipment is in a coordinated multi-point transmission/reception (CoMP) mode, the SRS sending unit sends the SRS based on CoMP to the serving base station and the coordinated base station.

22. The user equipment of claim 20, further comprising:

the data processing unit is used for merging the data from the service base station and/or the cooperative base station according to the scheduling information when the scheduling information acquisition unit acquires the information indicating that the user equipment enters the downlink cooperative mode from the service base station; and instructing a transmitter optimization unit to execute corresponding transmitter optimization processing when the scheduling information acquisition unit acquires the information that the serving base station instructs the user equipment to enter the uplink cooperation mode.

23. The UE of claim 22, wherein the UE is configured to perform the following steps

The data processing unit is further configured to obtain communication environment information, and feed back the communication environment information to the base station via the transceiver unit, where the communication environment information includes at least one of the following information: channel state characteristic information reflecting the channel state characteristics, and adjacent cell interference information.

24. A channel state information acquisition method comprises the following steps:

detecting Sounding Reference Signals (SRS) sent by user equipment by a serving base station and a cooperative base station;

the serving base station and the cooperative base station acquire channel state information according to the detected SRS;

the service base station and the cooperative base station cooperatively perform joint resource scheduling based on channel state information required by resource allocation;

the service base station and the cooperative base station exchange scheduling information after joint resource scheduling;

the user equipment optimizes the transmitter according to the scheduling information after the joint resource scheduling sent by the service base station; and

the user equipment sends data and/or signaling to the serving base station and/or the cooperating base station.

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