CN111224763A

CN111224763A - Downlink transmission method and user terminal equipment

Info

Publication number: CN111224763A
Application number: CN201910492392.0A
Authority: CN
Inventors: 李迎阳; 孙程君
Original assignee: Beijing Samsung Telecommunications Technology Research Co Ltd; Samsung Electronics Co Ltd
Current assignee: Beijing Samsung Telecommunications Technology Research Co Ltd; Samsung Electronics Co Ltd
Priority date: 2013-03-11
Filing date: 2013-10-28
Publication date: 2020-06-02
Anticipated expiration: 2033-10-28
Also published as: CN104052572B; CN104052572A; HK1202195A1; CN111224763B

Abstract

The application discloses a downlink transmission method and user terminal equipment, comprising the following steps: the UE receives the configuration information sent by the base station and correspondingly adjusts the CQI table and the MCS table; the UE measures and reports downlink channel quality information to the base station, wherein the UE can report CQI information according to a backward compatible CQI table or a CQI table supporting 256QAM modulation; the UE receives downlink scheduling information transmitted by the base station and correspondingly receives downlink data transmitted by the base station, and the UE may process MCS information in the DCI information according to a backward compatible MCS table or an MCS table supporting 256QAM modulation. The method and the device can generate a CQI table and an MCS table supporting 256QAM transmission, and support the selection of the CQI/MCS table using the existing LTE standard or the selection of the CQI/MCS table using 256QAM according to the link state of the UE.

Description

Downlink transmission method and user terminal equipment

Technical Field

The present invention relates to a wireless communication system, and more particularly, to a downlink transmission method and a user equipment.

Background

In the 3GPP LTE system, each radio frame is 10ms in length, equally divided into 10 subframes. A downlink Transmission Time Interval (TTI) is defined in a subframe. As shown in fig. 1, each downlink subframe includes two slots, and each slot includes 7 OFDM symbols for a general Cyclic Prefix (CP) length; for extended CP length, each slot contains 6 OFDM symbols. In each subframe, the first n OFDM symbols, n being equal to 1, 2 or 3, are used to transmit downlink control information, including a Physical Downlink Control Channel (PDCCH) and other control information; the remaining OFDM symbols are used to transmit PDSCH or Enhanced PDCCH (EPDCCH). The granularity of resource allocation is physical resource blocks PRB, and one PRB includes 12 consecutive subcarriers in frequency, and corresponds to one slot in time. Two PRBs in two slots on the same subcarrier within one subframe are referred to as one PRB pair. Within each PRB pair, each Resource Element (RE) is the smallest unit of time-frequency resources, i.e., one subcarrier in frequency and one OFDM symbol in time. The REs may be respectively used for different functions, e.g., a portion of the REs may be respectively used for transmitting a cell-specific reference signal (CRS), a user-specific demodulation reference signal (DMRS), a channel quality indication reference signal (CSI-RS), and the like.

In the LTE system, a plurality of transmission modes for transmitting data are defined, for example, for the downlink direction, a closed loop Multiple Input Multiple Output (MIMO) transmission mode, an open loop MIMO mode, a transmit diversity transmission mode, and the like are included. For a transmission mode, the system configures a normal Downlink Control Information (DCI) format for completing normal data transmission of the transmission mode; meanwhile, the base station also configures the UE to detect a regression DCI format, the regression DCI format generally has less bit number, and data is scheduled by adopting a more conservative mode, such as transmitting diversity or single antenna transmitting data, so that the reliability is higher.

In the LTE system, DCI transmitted to different UEs or DCI with different functions are independently encoded and transmitted. When physical resource mapping is performed on the PDCCH, the PDCCH is taken as a unit of a Control Channel Element (CCE); when physical resource mapping is performed on the EPDCCH, the physical resource mapping is in units of enhanced CCEs (ECCEs). In the following description, when it is not necessary to particularly distinguish between PDCCH and EPDCCH, they are collectively referred to as (E) PDCCH; accordingly, CCEs and ECCEs are collectively referred to as (E) CCEs. Specifically, i.e., the modulation symbols of one (E) PDCCH may be mapped onto L (E) CCEs, L may be equal to 1, 2, 4, 16, or 32, also referred to as the aggregation level of the (E) PDCCH. (E) The PDCCH is fixed using a QPSK modulation method, and the base station may select an (E) CCE aggregation level for transmitting the (E) PDCCH according to the number of bits of control information and a link condition of the UE.

In the existing LTE release, QPSK, 16QAM, and 64QAM based downlink data transmission is supported. As shown in table 1, the index of the coding modulation scheme (MCS) and Transport Block Size (TBS) used for downlink transmission is shown. Specifically, in the existing LTE release, in the DCI information, 5 bits are used to indicate MCS and TBS information, where 29 codewords indicate both modulation scheme and TBS, the last 3 codewords indicate only modulation scheme, and the TBS information is obtained according to the previous DCI information and can be used for retransmission of PDSCH.

Table 1: MCS and TBS for PDSCH transmissions

Accordingly, in order to support the base station to schedule downlink PRB resources, the UE needs to report link state indication information (CSI), including channel quality indication information (CQI). As shown in table 2, information such as a modulation scheme and a coding rate corresponding to each CQI index is shown. Specifically, in the existing LTE release, CQI information is reported with 4 bits. In accordance with the MCS configuration in the existing LTE release, only the case of performing downlink data transmission based on QPSK, 16QAM, and 64QAM is currently supported in the measurement of CQI.

Table 2: CQI information

In LTE release 12, to increase the peak downlink transmission rate of small cells, one possible candidate technique is to support PDSCH transmission based on 256QAM modulation. In a typical network configuration, such as using macro base stations on lower frequencies to achieve a large coverage range; and some small base stations are configured on higher frequencies to achieve hot spot coverage. Because the small base station uses high frequency points, the propagation characteristics of the small base station determine that the interference between cells is small, and the interference from the macro base station is avoided, so that the signal-to-noise ratio (SINR) of the UE in the small cell can be very large, and the downlink transmission based on 256QAM can be completely supported. In order to introduce the support of 256QAM, the processing methods of MCS and CQI in the existing LTE specifications need to be modified accordingly, and a series of problems caused by the modifications are solved.

Disclosure of Invention

The application discloses a downlink transmission method and user terminal equipment, which can support 256QAM modulation and optimize downlink transmission performance.

In order to achieve the purpose, the following technical scheme is adopted in the application:

a downlink transmission method comprises the following steps:

UE measures and reports downlink channel quality indication CQI information to a base station; wherein the UE reports the CQI information according to a backward compatible CQI table or a CQI table supporting 256QAM modulation;

the UE receives downlink scheduling information sent by the base station and correspondingly receives and processes downlink data sent by the base station according to Modulation Coding Scheme (MCS) information in Downlink Control Information (DCI) in the downlink scheduling information; wherein the UE processes the MCS information according to a backward compatible MCS table or an MCS table supporting 256QAM modulation.

Preferably, the CQI table supporting 256QAM modulation is:

in the backward compatible CQI table, removing a plurality of CQI items with the lowest spectrum efficiency and correspondingly adding a CQI item modulated by 256 QAM;

or, in the backward compatible CQI table, keeping a plurality of CQI items with the lowest coding rate unchanged, removing a plurality of QPSK modulated or 16QAM modulated CQI items, and correspondingly adding 256QAM modulated CQI items;

or, in the backward compatible CQI table, increasing the granularity of feedback for CQI items whose spectral efficiency is within a set range, and correspondingly increasing CQI items modulated by 256 QAM;

and/or removing a plurality of 64QAM modulated CQI items with the highest coding rate in the backward compatible CQI table, and correspondingly adding 256QAM modulated CQI items.

Preferably, the CQI table supporting 256QAM modulation is:

removing a plurality of CQI items with the lowest spectrum efficiency from the backward compatible CQI table, and replacing the CQI items with CQI items modulated by 256 QAM;

or, in the backward compatible CQI table, keeping a plurality of CQI items with the lowest coding rate unchanged, and replacing a plurality of CQI items with QPSK or 16QAM modulation modes with CQI items modulated by 256 QAM;

or, in the backward compatible CQI table, replacing a part of CQI items of which the spectrum efficiency is within a set range with CQI items modulated by 256 QAM;

and/or, in the backward compatible CQI table, replacing one or a plurality of 64QAM modulated CQI items with the highest coding rate correspondingly with 256QAM modulated CQI items.

Preferably, the CQI table supporting 256QAM modulation is: adding a 256QAM modulated CQI entry in the backward compatible CQI table.

Preferably, when the UE reports the CQI information according to a CQI table supporting 256QAM modulation, the method further comprises:

increasing the bit number occupied by the CQI information, and indicating the CQI index of the reported CQI information in the CQI table supporting 256QAM modulation; alternatively, the first and second electrodes may be,

the UE reports an offset value to the base station when reporting the CQI information, and the offset value is used for indicating the actual index of the CQI information of the base station in the CQI table supporting 256QAM modulation; alternatively, the first and second electrodes may be,

and the UE receives an offset value sent by a base station, and extracts partial CQI items from the CQI table supporting 256QAM modulation according to the offset value to form a CQI table actually used when reporting the CQI information.

Preferably, the method further comprises: a base station respectively configures a CQI table used by each subframe set of the UE;

and the UE reports the CQI information according to a CQI table used by the subframe set to which the CQI information belongs.

Preferably, the method further comprises: the base station respectively configures a CQI table used by each CSI process of the UE;

and the UE reports the CQI information according to a CQI table used by the CSI process to which the CQI information belongs.

Preferably, the method further comprises: a base station respectively configures a CQI table used by each CSI process and subframe set of the UE;

and the UE reports the CQI information according to the CSI process to which the CQI information belongs and a CQI table used by a subframe set.

Preferably, the method further comprises: and the UE receives configuration information sent by the base station and is used for configuring the CQI table supporting 256QAM modulation or a backward compatible CQI table to report the CQI information.

Preferably, the MCS table supporting 256QAM modulation is:

removing a plurality of QPSK modulated MCS items with the lowest coding rate and adding 256QAM modulated MCS items in the backward compatible MCS table;

or, in the backward compatible MCS table, keeping the MCS items of the QPSK modulation with the lowest coding rate unchanged, removing the MCS items of the QPSK modulation or the 16QAM modulation, and adding the MCS items of the 256QAM modulation;

or, in the backward compatible MCS table, removing the MCS item of which the spectrum efficiency obtained by interpolation is within the set range, and adding the MCS item of 256QAM modulation;

or, when the CQI table supporting 256QAM is a CQI table in which several CQI items in the backward compatible CQI table are removed and 256QAM modulated CQI items are added, removing MCS items corresponding to the removed CQI items and adding 256QAM modulated MCS items in the backward compatible MCS table;

and/or, in the backward compatible MCS table, removing one or a plurality of 64QAM modulated MCS items with the highest coding rate, and correspondingly adding 256QAM modulated MCS items;

and/or, in the backward compatible MCS table, removing one of a plurality of MCS items with equal spectrum efficiency and correspondingly adding the MCS item of 256QAM modulation.

Preferably, the MCS table supporting 256QAM is:

in the backward compatible MCS table, replacing a plurality of QPSK modulated MCS items with lowest coding rate with MCS items modulated by 256 QAM;

or, in the backward compatible MCS table, keeping the MCS items of the QPSK modulation with the lowest coding rate unchanged, and replacing the MCS items of the QPSK modulation or the 16QAM modulation with the MCS items of the 256QAM modulation;

or, in the backward compatible MCS table, replacing the MCS item of which the spectrum efficiency obtained by interpolation is within the set range with the MCS item modulated by 256 QAM;

or, when the CQI table supporting 256QAM is a CQI table in which several CQI items in the backward compatible CQI table are removed and 256QAM modulated CQI items are added, replacing, in the backward compatible MCS table, an MCS item corresponding to the removed CQI item with the 256QAM modulated MCS item;

and/or, in the backward compatible MCS table, correspondingly replacing one or a plurality of 64QAM modulated MCS items with the highest coding rate with 256QAM modulated MCS items;

and/or, in the backward compatible MCS table, correspondingly replacing one of a plurality of MCS items with equal spectrum efficiency with the MCS item modulated by 256 QAM;

and/or, in the backward compatible MCS table, reserving I_MCSMCS entry of 0, one or more I_MCS>The MCS item of 0 is correspondingly replaced by the MCS item of 256QAM modulation; wherein, I_MCSIndicating the MCS index value.

Preferably, the MCS table supporting 256QAM modulation is: adding a 256QAM modulated MCS entry in the backward compatible MCS table.

Preferably, when the UE processes the MCS information according to an MCS table supporting 256QAM modulation, the method further comprises:

increasing the bit number occupied by the MCS information, and indicating the MCS index of the reported MCS information in the MCS table supporting 256QAM modulation; alternatively, the first and second electrodes may be,

and the UE receives the offset value sent by the base station and extracts partial MCS items from the MCS table supporting 256QAM modulation according to the offset value to form an MCS table actually used for processing the MCS information.

Preferably, when the UE supports 256QAM, if the detected DCI format is a normal DCI format, the MCS table supporting 256QAM is used in processing the MCS information; if the detected DCI format is a regression DCI format, a backward compatible MCS table is used when the MCS information is processed.

Preferably, after the UE receives the downlink scheduling information, the method further includes: using the MCS table corresponding to the RE mapping and QCL configuration of the PDSCH indicated by the downlink scheduling information as the MCS table used when processing the MCS information; wherein, the MCS table corresponding to each RE mapping and QCL configuration of the PDSCH is pre-configured for the base station.

Preferably, after the UE receives the downlink scheduling information, the method further includes: and (E) PDCCH used for bearing the downlink scheduling information and detected by the UE is located in an MCS table used when the USS or CSS determines to process the MCS information.

Preferably, after the UE receives the downlink scheduling information, the method further includes: and using the MCS table corresponding to the aggregation level of the (E) PDCCH for bearing the downlink scheduling information as the MCS table used for processing the MCS information.

Preferably, the MCS table used in processing the MCS information is determined according to whether the type of (E) PDCCH is localized or distributed.

Preferably, after the UE receives the downlink scheduling information, the method further includes: taking an MCS table corresponding to an EPDCCH set where the EPDCCH for bearing the downlink scheduling information is located as an MCS table used when the MCS information is processed; wherein, the MCS table corresponding to each EPDCCH set of the UE is pre-configured for the base station.

Preferably, the method further comprises: dividing downlink subframes into a plurality of sets, and configuring a MCS table used by DCI (Downlink control information) for scheduling downlink data transmission for each downlink subframe set;

after the UE receives the downlink scheduling information, the method further includes: and using the MCS table used by the DCI information as the MCS table used for processing the MCS information.

A user terminal device, comprising: a channel quality indicator CQI information measuring and reporting unit, a downlink scheduling information receiving unit and a downlink data receiving and processing unit;

the CQI information measuring and reporting unit is used for measuring and reporting the CQI information of the downlink channel quality indication to the base station; wherein the UE reports the CQI information according to a backward compatible CQI table or a CQI table supporting 256QAM modulation;

the downlink scheduling information receiving unit is used for receiving downlink scheduling information sent by the base station;

the downlink data receiving and processing unit is configured to correspondingly receive and process downlink data sent by the base station according to Modulation and Coding Scheme (MCS) information in Downlink Control Information (DCI) included in the downlink scheduling information; wherein the UE processes the MCS information according to a backward compatible MCS table or an MCS table supporting 256QAM modulation.

By adopting the method and the equipment, the CQI table and the MCS table supporting 256QAM transmission can be generated, and the CQI/MCS table of the existing LTE standard or the CQI/MCS table supporting 256QAM can be selected and used according to the link state of the UE, so that the performance of downlink transmission is optimized.

Drawings

The foregoing and/or additional aspects and advantages of embodiments of the present application will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram of a subframe structure;

fig. 2 is a flowchart of a downlink transmission method according to the present application;

fig. 3 is a diagram of different CQI tables used for different CSI processes;

fig. 4 is a diagram illustrating different MCS tables corresponding to different downlink subframe sets.

Detailed Description

For the purpose of making the objects, technical means and advantages of the present application more apparent, the present application will be described in further detail with reference to the accompanying drawings.

The existing release of the LTE only supports 3 modulation modes such as QPSK, 16QAM and 64 QAM. These 3 modulation schemes cover the transmission requirements in various typical situations. I.e., supporting QPSK-based transmission when channel conditions are poor and 64 QAM-based transmission when channel conditions are good. And only in some scenes with particularly high SINR, downlink transmission can be carried out based on 256QAM, so that the downlink peak rate is improved. In fact, even under good channel conditions, the link condition of the UE is not always sufficient for downlink transmission based on 256QAM, considering dynamic changes of interference, fast fading and slow fading of the link, corner effect, etc., that is, it is necessary to support switching between modulation schemes such as 256QAM, 64QAM, 16QAM, and QPSK. In some cases, the MCS table or CQI table in the existing version of LTE is already suitable for downlink transmission of the UE; in other cases, the newly defined MCS table or CQI table for supporting 256QAM is better suited to handle downlink transmission of the UE.

Fig. 2 is a specific flowchart of a downlink transmission method in the present application. As shown in fig. 2, the method includes:

step 201: the UE receives the configuration information sent by the base station and adjusts the CQI table and MCS table accordingly.

In step 201, the UE uses the CQI table and the MCS table in the existing LTE release by default, which ensures that the UE can smoothly access the base station of the existing LTE release and the base station of the new LTE release. In fact, the system must now operate according to the existing version of LTE, since the base station does not know whether the UE supports 256QAM transmission before reporting its capabilities. For a UE supporting 256QAM, when the base station knows that the link status of the UE can support 256QAM transmission, the UE can be configured to operate in the mode supporting 256QAM using higher layer signaling. At this time, the MCS table and the CQI table are changed from the existing LTE standard, support for 256QAM is provided, and related parameters need to be set. In step 202 and step 203, relevant parameters that may need to be set are described in detail below.

Step 202: the UE measures and reports downlink channel quality information to the base station, where the UE may report CQI information in a backward compatible CQI table or a CQI table supporting 256QAM modulation.

In step 202, support for 256QAM is added by extending the CQI table of the existing version of LTE. Two preferred methods of configuring the CQI table are described below.

The first method is to define one or more new CQI tables supporting 256QAM based on CQI tables in existing releases of LTE. And if the number of the new CQI tables is N, N +1 CQI tables are supported in the LTE system of the new version. When the UE needs to be configured to use 256QAM, the base station configures the UE to use a CQI table supporting 256QAM by using high-layer signaling. For example, if only one new CQI table supporting 256QAM is defined, the CQI table of the UE using the existing LTE standard or the CQI table supporting 256QAM may be configured with 1-bit signaling.

Assuming that the average channel state of one UE is good and can support 256QAM, the probability that the same UE is in a poor channel state in a short time is generally small. One way to generate a CQI table that supports 256QAM is to remove some of the CQI terms of the existing CQI table that have lower modulation orders and add terms that employ 256 QAM. The preferred method of the present application is described below. Here, the CQI index 0 may be used to indicate an invalid CQI value, consistent with the existing CQI table, or all 16 values indicate valid CQI information in a table supporting 256 QAM.

In the first method, one method for generating a CQI table supporting 256QAM is to remove several CQI entries having the lowest spectral efficiency in the existing CQI table, renumber the remaining CQI entries of QPSK/16QAM/64QAM in sequence, and then add the entries of 256 QAM. For example, 5 items with the smallest index in the existing CQI table are removed, so that 5 items supporting 256QAM can be added. Here, several CQI items refer to one or more CQI items.

In order to cope with the situation that the channel of the UE is deeply degraded, it may be necessary to reserve some QPSK terms with lower coding rate for the case that the channel of the UE can support 256 QAM. Thus, when configuring the CQI table of 256QAM, another method for generating the CQI table supporting 256QAM may be to remove several QPSK entries or even 16QAM entries, sequentially renumbering the remaining CQI entries of other QPSK/16QAM/64QAM, and then adding the entries of 256QAM on the premise of keeping the several QPSK entries with the lowest or relatively low coding rate in the existing CQI table unchanged. For example, indexes 2-6 in the existing CQI table are removed, so that 5 items supporting 256QAM can be added.

There is also a method for generating a CQI table supporting 256QAM, which may be to increase the granularity of feedback for the CQI entries with lower spectral efficiency based on the existing CQI table, for example, for the CQI entries with lower spectral efficiency, only one of every two CQI entries is reserved, that is,

CQI entries

2, 4, 6 and 8 are removed; the remaining QPSK/16QAM/64QAM CQI terms are renumbered in turn and then 256QAM terms are added. With this approach, the CQI table supporting 256QAM can still cover all channel states, but with the granularity of the CQI entries being less spectrally efficient increased.

The above methods all remove some items of the existing CQI tables and renumber the remaining CQI items, and when defining a new CQI table supporting 256QAM, may also directly replace some items of the CQI table to be removed with items of 256QAM without changing the modulation order and spectral efficiency represented by other CQI items in the CQI table. Specifically, according to the above method for removing CQI table entries, some CQI entries with the lowest spectral efficiency in the existing CQI table may be replaced with entries using 256 QAM; or, on the premise of keeping a plurality of QPSK items with the lowest or lower coding rate in the existing MCS table, replacing a plurality of QPSK items, even 16QAM items, with 256QAM items; or, on the basis of the existing CQI table, granularity of feedback may be increased for the CQI items with lower spectral efficiency, for example, for the CQI items with lower spectral efficiency, one of every two CQI items is replaced with the item of 256 QAM.

In the above method of generating a CQI table supporting 256QAM, some CQI items having low spectral efficiency are reduced to indicate 256 QAM. In fact, the CQI table in the existing standard supports 64QAM and coding rate up to 0.92, and on the premise that the UE can support 256QAM, the performance of using 64QAM and coding rate up to 0.92 may not be optimized, and some CQI items transmitted based on 256QAM may be replaced. That is, in addition to reducing some of the less spectrally efficient CQI terms mentioned above to indicate 256QAM, one or more 64QAM terms having the highest coding rate may be removed to indicate 256 QAM. Specifically, the method of removing one or more 64QAM entries to indicate 256QAM may be used alone to generate a new CQI table, or may be combined with the aforementioned method of reducing the spectral efficiency of the CQI entry indicating 256QAM to generate a new CQI table.

The second method is to add items corresponding to 256QAM to a CQI table in the existing LTE release, so as to obtain a long CQI table with a length exceeding 16 items, that is, the long CQI table contains information of CQI indexes exceeding 16 items. In this case, since the length of the CQI table exceeds 16 entries, the reporting method of the CQI information needs to be reconsidered.

One way to report the CQI may be to increase the number of bits for the UE to report the CQI, for example, to feed back the CQI with 5 bits.

Or, the number of bits of the CQI information with 4 bits may also be kept unchanged, so that the CQI reporting mechanism of the existing LTE version may be reused directly, and further, the UE feeds back an offset value while feeding back the CQI information with 4 bits, where the offset value is used to indicate an actual index of the CQI information reported by the base station in the long CQI table supporting 256QAM modulation. For example, noting that the value of 4-bit CQI is c, the offset value is v, a CQI value of c equal to 0 may still represent an invalid CQI value; and for the CQI value c equal to 1-15, the actual index of the CQI fed back by the UE is the CQI index c + v in the long CQI table. The offset value v may be jointly encoded with rank indication information (RI) in CSI feedback information of the UE and fed back at the same timing position.

Or, the 4-bit CQI may also be kept unchanged, so that the CQI reporting mechanism of the existing LTE version may be reused directly, when it is necessary to configure the UE to use 256QAM, the base station configures an offset value v of a CQI table for the UE by using high-level signaling, and the UE extracts 16 CQI entries from the long CQI table according to the offset value v, thereby forming a CQI table actually configuring the UE. For example, in this actually configured CQI table, a CQI value of 0 may still represent an invalid CQI value, and a CQI value c (c equals 1-15) may be mapped in turn to the CQI index c + v of the long CQI table described above.

In LTE release 10, in order to support the elcic technique, downlink subframes of a cell may be divided into two sets, channel states of the two sets are different, and accordingly, CSI information may be fed back to the two subframe sets respectively. That is, the base station may configure the UE to report the feedback information of the two subframe sets respectively. The average SINR levels of the plurality of subframe sets are generally different. As shown in fig. 3, for example, eICIC is used, a subframe set of ABSF is configured for a macro base station, that is, interference from the macro base station on a small cell is small, so the SINR of the UE may be large, and it may be suitable for using a 256QAM modulation scheme; for the other subframe set, the macro base station sends downlink control and downlink data, so the SINR of the UE is relatively small, and the UE may not support a 256QAM modulation scheme.

The application provides that when a base station configures a plurality of subframe sets of UE, the base station respectively configures the information of a CQI table used by each subframe set. If a new table is defined for 256QAM, the UE is configured to adopt a CQI table in the existing LTE version or a new CQI table supporting 256QAM according to the SINR condition of the subframe set. If the long CQI table is defined, the UE is configured to select the offset value v of the CQI index from the long CQI table according to the SINR condition of the subframe set. For example, a CQI value of 0 may still represent an invalid CQI value, while a CQI value c (c equals 1-15) may be mapped in turn to the CQI index c + v of the long CQI table described above. In this way, when configuring the CSI reporting method of the UE, the base station may set information of the CQI table used by the base station for each subframe set. Correspondingly, the UE receives the information of the CQI tables respectively set by the base station for each subframe set, measures the channel state for each subframe set, and feeds back the CQI information according to the CQI tables configured by the base station for the subframe set.

In LTE release 11, in order to support data transmission for CoMP, configuring the UE to report feedback information of multiple CSI processes is further supported, and each CSI process may be further divided into two subframe sets. In summary, in existing LTE systems, configuring a UE to feed back feedback information for multiple CSI processes and multiple subframe sets has been supported. The average SINR levels of the multiple CSI processes and the multiple subframe sets are generally different. On a part of CSI processes and subframe sets, the SINR of the UE can be very large, and the method is possibly suitable for adopting a 256QAM modulation mode; on the other part of CSI process and the subframe set, the SINR of the UE is small, and the 256QAM modulation mode may not be supported.

The application provides that when a base station configures a plurality of CSI processes of UE, information of a CQI table used by each CSI process is configured respectively. If a new table is defined for 256QAM, the UE is configured to adopt a CQI table in the existing LTE release or a new CQI table supporting 256QAM according to the SINR condition of the CSI process. If the long CQI table is defined, the UE is configured to select the offset value v of the CQI index from the long CQI table according to the SINR condition of the CSI process. For example, a CQI value of 0 may still represent an invalid CQI value, while a CQI value c (c equals 1-15) may be mapped in turn to the CQI index c + v of the long CQI table described above. In this way, when the base station configures the CSI reporting method of the UE, the information of the CQI table used by the base station may be set for each CSI process. Correspondingly, the UE receives the information of the CQI table respectively set by the base station for each CSI process, measures the channel state for each CSI process, and feeds back the CQI information according to the CQI table configured by the base station for the CSI process.

The application further provides that when the base station configures a plurality of CSI processes and subframe sets of the UE, the base station configures the information of the CQI table used by each CSI process and each subframe set respectively. If a new table is defined for 256QAM, the UE is configured to adopt a CQI table in the existing LTE version or a new CQI table supporting 256QAM according to the SINR condition of one CSI process and a subframe set. If the long CQI table is defined, the UE is configured to select the offset value v of the CQI index from the long CQI table according to the SINR condition of one CSI process and a subframe set. For example, a CQI value of 0 may still represent an invalid CQI value, while a CQI value c (c equals 1-15) may be mapped in turn to the CQI index c + v of the long CQI table described above. In this way, when the base station configures the CSI reporting method of the UE, the information of the CQI table used by the base station may be set for each CSI process and subframe set. Correspondingly, the UE receives the information of the CQI tables respectively set by the base station for each CSI process and subframe set, measures the channel state for each CSI process and subframe set, and feeds back the CQI information according to the CQI tables configured by the base station for the CSI process and the subframe set.

Step 203: the UE receives the downlink scheduling information transmitted by the base station and correspondingly receives and processes the downlink data transmitted by the base station according to the MCS information in the DCI information, wherein the MCS information in the DCI information can be processed by the UE according to a backward compatible MCS table or an MCS table supporting 256QAM modulation.

In step 203, support for 256QAM is added by extending the MCS table of the existing LTE release. Two preferred methods of configuring the MCS table are described below.

The first method is to define one or more new MCS tables supporting 256QAM based on MCS tables in the existing LTE release. And if the number of the new MCS tables is recorded to be N, the new LTE system supports N +1 MCS tables. Here, base station devices supporting 256QAM may be classified into different classes, for example, simple devices only support using 256QAM at a not too high coding rate; while complex devices may support very high coding rates when 256QAM is used. The MCS tables configuring different 256QAM may be allocated corresponding to different levels of base station apparatuses supporting 256QAM, which is one reason why a plurality of 256QAM are defined above. Alternatively, to simplify the design, only one common new MCS table may be defined for all base stations supporting 256 QAM. When the UE needs to be configured to use 256QAM, the base station configures the UE with a MCS table supporting 256QAM by using high-layer signaling.

Assuming that the average channel state of one UE is good and can support 256QAM, the probability that the same UE needs to use a modulation scheme with a lower modulation order is generally small. One way to generate an MCS table that supports 256QAM is to remove some MCS entries with lower modulation orders in the existing MCS table and add entries modulated with 256 QAM. The preferred method of the present application is described below. Here, in accordance with the existing MCS table, the maximum several MCS values may indicate only modulation orders without including TBS information. The following description refers to the MCS entries indicating modulation order and TBS simultaneously only for the other.

In the first method, one method for generating an MCS table supporting 256QAM is to remove some QPSK entries having the lowest coding rate in the existing MCS table, renumber the remaining MCS entries of QPSK/16QAM/64QAM in order from 0, and then add 256QAM entries. For example, 5 items with the smallest index in the existing MCS table are removed, so that 5 items supporting 256QAM can be added.

In order to cope with the situation that the channel of the UE is deeply degraded, it may be necessary to reserve several QPSK terms with lower coding rates for the case that the channel of the UE can support 256 QAM. Thus, when configuring the MCS table of 256QAM, another method for generating the MCS table supporting 256QAM may be to remove several QPSK entries or even 16QAM entries, sequentially renumbering the remaining MCS entries of other QPSK/16QAM/64QAM, and then adding the entries of 256QAM on the premise of keeping the several QPSK entries with the lowest or relatively low coding rate in the existing MCS table unchanged. For example, the indexes 2-6 in the existing MCS table are removed, so that 5 items supporting 256QAM can be added. Here, several MCS entries refer to one or more MCS entries.

In addition, in the existing MCS table, some MCS entries actually correspond directly to CQI entries in the CQI table, and other MCS entries are obtained by interpolation, so there is also a method of generating a MCS table supporting 256QAM by removing MCS entries in the existing MCS table whose spectral efficiency obtained by interpolation is within a specified range (for example, MCS entries whose spectral efficiency is lower), renumbering the remaining MCS entries of QPSK/16QAM/64QAM in order from 0, and then adding entries of 256 QAM. For example,

indexes

1, 3, 5, 7, and 9 in the existing MCS table are removed, so that 5 items supporting 256QAM can be added.

In fact, there is a corresponding relationship between CQI entries in the CQI table and MCS entries in the MCS table, so if several CQI entries in the existing CQI table are removed when generating the CQI table supporting 256QAM, accordingly, MCS entries corresponding to these removed CQI entries in the existing MCS table may be removed, and remaining MCS entries of other QPSK/16QAM/64QAM are renumbered in turn, and then 256QAM entries are added.

The above methods all remove some entries of the existing MCS table and renumber the remaining MCS entries, and when defining a new MCS table supporting 256QAM, it is also possible to directly replace some entries of the MCS table to be removed with entries of 256QAM, while keeping the modulation order and TBS represented by other MCS entries in the MCS table unchanged. Specifically, the method for removing the MCS table entries in the above embodiment may replace QPSK entries with a lower coding rate in the existing MCS table with entries modulated by 256 QAM; or, on the premise of keeping a few QPSK entries with the lowest or relatively low coding rate in the existing MCS table, some QPSK entries, even 16QAM entries, may be replaced with 256QAM entries; alternatively, it may beReplacing an MCS item with low spectrum efficiency obtained by interpolation in the existing MCS table with an item of 256 QAM; alternatively, in accordance with the method of generating the CQI table supporting 256QAM, the MCS entries corresponding to these removed CQI entries in the existing MCS table may be replaced with the entries of 256 QAM; or, because MCS index 0 is I_MCSOther special uses are 0, so that I can be avoided_MCSRedefining 0 as indicating 256QAM modulation mode, one or more I_MCS>The other MCS entries of 0 are replaced with entries indicating 256QAM, the invention does not limit which I is specifically employed_MCS>The MCS entry of 0 indicates the modulation scheme of 256 QAM. Here, when the transmission scheme of dual Transport Blocks (TBs) is adopted, for example, in DCI formats 2, 2A, 2B, 2C, and 2D, it is by setting I corresponding to one TB_MCS0 and rv_idxIndicating that this TB is not currently transmitted 1. If I_MCSReuse of 0 for indicating 256QAM modulation scheme would result in the inability to utilize rv_idxSince HARQ retransmission is performed at 1, which affects the performance of 256QAM data transmission, MCS index I_MCS0 may not be used to indicate the 256QAM modulation scheme.

This method can ensure that no confusion of MCS information in DCI occurs when configuring and reconfiguring downlink transmission modes. According to the design of the LTE system, for each downlink transmission mode, the UE simultaneously detects two DCI formats, namely a normal format and a regression format. In this method, when the network configures the UE to use the MCS table supporting 256QAM, it may be that two DCI formats simultaneously adopt the MCS table supporting 256 QAM. The new MCS table supporting 256QAM contains some MCS items, the modulation order represented by the MCS items and the TBS are the same as the definition of the corresponding MCS index in the existing MCS table, so when configuring and reconfiguring the downlink transmission mode, as long as the regression DCI format is used and the MCS items consistent with the two tables are used, the confusion of the MCS information in the DCI is avoided.

In the method for generating the MCS table supporting 256QAM, some MCS entries having lower modulation orders are reduced to indicate the modulation scheme of 256 QAM. In fact, the MCS table in the existing standard supports 64QAM and coding rate up to 0.92, and on the premise that the UE can support 256QAM, the performance of using 64QAM and coding rate up to 0.92 may not be optimized, and some MCS entries based on 256QAM transmission may be replaced. That is, in addition to reducing some MCS entries with lower modulation orders to indicate 256QAM, one or more 64QAM entries with the highest coding rate may be removed to indicate the modulation scheme and corresponding TBS of 256 QAM. Specifically, the method of removing one or more 64QAM entries to indicate 256QAM may be used alone to generate a new MCS table, or may be combined with the aforementioned method of reducing the MCS entry with a lower modulation order to indicate 256QAM to generate a new MCS table.

In addition, some MCS entries having equal spectral efficiency but different modulation schemes exist in the conventional MCS table. I.e., MCS indexes 10 and 11 are equal in spectral efficiency but QPSK and 16QAM, respectively, and MCS indexes 16 and 17 are equal in spectral efficiency but 16QAM and 64QAM, respectively. One of the two MCSs with equal spectral efficiency may be removed to obtain one codeword to indicate a 256QAM transmission. For example, terms with equal spectral efficiency but lower modulation order are removed. With this approach, two codewords may be obtained for indicating a 256QAM transmission.

The second method is to add entries corresponding to 256QAM to the MCS table in the existing LTE release, so that the long MCS table with length exceeding 32 entries, i.e. the long MCS table contains information of MCS index exceeding 32 entries. In this case, since the MCS table length exceeds 32 entries, it is necessary to reconsider the MCS information representation.

One way to express this may be to increase the number of bits occupied by MCS information in the DCI format, e.g., to support MCS information with 6 bits.

Or, the 5-bit MCS can be kept unchanged, so that the DCI format of the existing LTE version can be reused directly; further, when the UE needs to be configured to use 256QAM, the base station configures an offset value v of an MCS table for the UE by using high-level signaling, and the UE extracts 32 MCS items from the long MCS table according to the offset value v to form an MCS table actually configuring the UE. For example, in this actually configured CQI table, MCS values 28, 29, 30 and 31 in the DCI indicate modulation orders of 2, 4, 6 and 8, respectively (i.e., QPSK, 16QAM, 64QAM and 256QAM, respectively), consistent with the existing MCS table structure, and MCS value m (m is equal to 0-27) in the DCI may be sequentially mapped to MCS index m + v of the above-described long MCS table. Different offset values v can be configured for the UE corresponding to different levels of base station equipment supporting 256QAM, thereby optimizing the downlink performance.

The MCS table generation method supporting 256QAM modulation is described above. For a UE supporting 256QAM, an MCS table adopting the existing LTE standard or an MCS table supporting 256QAM is configurable. In some cases, the MCS table in the existing LTE release is already suitable for downlink transmission of the UE; in other cases, the newly defined MCS table for supporting 256QAM is better suited to increase the peak downlink transmission rate of the UE. The method of configuring the MCS table of the existing LTE standard or the MCS table supporting 256QAM of the present application is described below.

According to the design of the LTE system, for each downlink transmission mode, the UE simultaneously detects two DCI formats, namely a normal format and a regression format. The normal DCI format is for completing normal data transmission of this transmission mode. For the case where the UE needs to be configured to use 256QAM, it is clear that the normal DCI format is to be able to support 256 QAM. The regression DCI format generally has a small number of bits and high reliability, and supports the conversion between downlink transmission modes. It can be seen that pursuing the peak downlink rate is not the primary use of the recursive DCI format.

The application provides that the normal DCI format and the regression DCI format detected by the UE can respectively use different MCS tables. Specifically, for a UE configured to support 256QAM, the MCS field in the normal DCI format may use an MCS table supporting 256QAM, that is, one of the MCS table using the existing LTE standard or the MCS table supporting 256QAM may be configured through high-layer signaling; while the MCS fields in the regressive DCI format still conform to the existing LTE standard, i.e., use the MCS table in the existing LTE standard. When the base station schedules downlink data transmission, the MCS table is selected according to the method of the application to set the MCS domain in the DCI according to the selected normal DCI format or the regression DCI format. Correspondingly, when the UE detects the (E) PDCCH in a blind manner, if the UE detects the (E) PDCCH in a normal DCI format in a blind manner and assumes that a high-level signaling configures an MCS table supporting 256QAM, the MCS information in the DCI is analyzed according to a new MCS table supporting 256QAM, otherwise, the MCS information in the DCI is analyzed according to the MCS table in the existing LTE standard; if the UE blindly detects (E) PDCCH of the regressive DCI format, the MCS information in the DCI is parsed according to the MCS table in the existing LTE standard.

By adopting the method, whether the UE is configured with 256QAM downlink transmission or not, the regression DCI format is consistent with the existing LTE standard, thereby ensuring that the MCS information in the DCI is not confused when the downlink transmission mode is configured and reconfigured.

According to the specification of LTE release 11, for transmission mode 10, the system can configure the configuration information of RE mapping and quasi co-location (QCL) of 4 different PDSCH through high layer signaling, and indicate which RE mapping and QCL configuration is used for the current PDSCH transmission through 2 bits in DCI format. For each different RE mapping and QCL configuration, the physical layer transmission technology for the RE mapping and QCL configuration may be different, and may be, for example, joint multipoint transmission (JT) or coordinated multipoint transmission (CS/CB). The link states are also different using different transmission techniques. For example, the SINR may be higher with JT than with CS/CB, so that it is possible to use an MCS table supporting 256QAM when JT is used, and only adapt to use the existing MCS table when CS/CB is used.

The application provides that when RE mapping and QCL configuration of a PDSCH of UE are configured, MCS tables correspondingly used by each RE mapping and QCL configuration are configured simultaneously and respectively. When a base station schedules downlink data transmission, after selecting RE mapping and QCL configuration of a PDSCH to be adopted by a UE, the base station sets an MCS domain in the DCI according to an MCS table configured with the RE mapping and the QCL configuration. Accordingly, after blind-detecting one (E) PDCCH, the UE determines an MCS table according to the RE mapping and QCL configuration of the PDSCH indicated by the UE, and parses MCS information in the DCI.

According to the LTE system design, the UE needs to blindly detect the (E) PDCCH transmitted by the base station in two search spaces, i.e. in the Common Search Space (CSS) and the UE-specific search space (USS). The (E) PDCCH transmitted in USS is typically used to trigger UE-specific PDSCH transmission, while CSS is typically used to transmit some cell-common (E) PDCCH. Also, for DCI formats with equal number of bits in USS and CSS, (E) PDCCH in CSS may trigger UE-specific PDSCH transmission. For a UE configured to support 256QAM, the (E) PDCCH in the USS needs to be able to support 256 QAM; for the (E) PDCCH in CSS, however, the MCS table supporting 256QAM need not be employed. Or, for configuring a UE supporting 256QAM, the (E) PDCCH in the USS needs to be able to support 256 QAM; in the CSS, different MCS tables may be set according to the usage of the (E) PDCCH transmitted.

The present application proposes to determine an MCS table to be used according to whether a (E) PDCCH detected by a UE is located in a USS or a CSS. Specifically, for a UE configured to support 256QAM, for an (E) PDCCH in the USS, an MCS table supporting 256QAM may be used, that is, one of an MCS table using the existing LTE standard or an MCS table supporting 256QAM may be configured through higher layer signaling; for (E) PDCCH in CSS, MCS table using existing LTE standard is fixed. When the base station schedules downlink data transmission, for (E) PDCCH in USS and CSS, MCS tables are selected according to the method of the application to set the MCS domain in the DCI. Correspondingly, when the UE detects the (E) PDCCH in the blind, assuming that the MCS table supporting 256QAM is configured in the higher layer signaling for the (E) PDCCH in the USS, the MCS information in the DCI may be parsed according to the MCS table supporting 256QAM, otherwise, the MCS information in the DCI is parsed according to the MCS table in the existing LTE standard; for (E) PDCCH in CSS, MCS information in DCI is parsed according to the MCS table in the existing LTE standard.

Or, for a UE configured to support 256QAM, for an (E) PDCCH in the USS, an MCS table supporting 256QAM may be used, that is, one of an MCS table using the existing LTE standard or an MCS table supporting 256QAM may be configured through higher layer signaling; for (E) PDCCH in CSS, if its DCI is cell-specific, e.g., scheduling broadcast information, paging information, or RACH response message (RAR), it uses the MCS table of the existing LTE standard; for (E) PDCCH in CSS, if its DCI is UE-specific, a MCS table supporting 256QAM may be used. When the base station schedules downlink data transmission, for (E) PDCCH in USS and CSS, MCS tables are selected according to the method of the application to set the MCS domain in the DCI. Correspondingly, when the UE detects the (E) PDCCH in the blind, assuming that the MCS table supporting 256QAM is configured in the higher layer signaling for the (E) PDCCH in the USS, the MCS information in the DCI may be parsed according to the MCS table supporting 256QAM, otherwise, the MCS information in the DCI is parsed according to the MCS table in the existing LTE standard; for (E) PDCCH in CSS, if the DCI is cell-specific, the MCS information in the DCI is analyzed according to the MCS table in the existing LTE standard; for the (E) PDCCH in CSS, if the DCI is UE-specific, it may be assumed that the higher layer signaling configures an MCS table supporting 256QAM, the MCS information in the DCI may be parsed according to the MCS table supporting 256QAM, otherwise, the MCS information in the DCI may be parsed according to the MCS table in the existing LTE standard.

In the LTE system, one (E) PDCCH is aggregated with one or more (E) CCEs. Generally, when the downlink channel quality of the UE is good, a smaller aggregation level may be used; while the downlink quality to the UE is poor, a relatively large aggregation level needs to be used. Correspondingly, for downlink data transmission, when the downlink quality is good, a 256QAM modulation scheme may be adopted; when the downlink quality is poor, the 256QAM modulation scheme cannot be generally adopted.

The present application proposes to determine an MCS table used for DCI according to an aggregation level of (E) PDCCH. For example, the (E) PDCCH of which aggregation level is less than K uses a new MCS table supporting 256QAM, and the (E) PDCCH of which aggregation level is greater than or equal to K uses an existing MCS table. When the base station schedules downlink data transmission, the base station determines (E) the aggregation level of the PDCCH according to the downlink state of the UE, and selects the MCS table according to the method of the application to set the MCS domain in the DCI. Correspondingly, after blind detection of one (E) PDCCH, the UE analyzes the MCS domain in the DCI according to the aggregation level of the PDCCH to obtain the modulation mode and TBS scheduled by the base station.

In the LTE system, two types of EPDCCH are defined, namely a localized EPDCCH and a distributed EPDCCH. In general, localized EPDCCH is applicable to a case where a base station may obtain relatively accurate Channel State Indication (CSI) information for different frequency subbands of a UE to obtain frequency scheduling gain; correspondingly, when the base station has no accurate CSI information of the UE, the base station has to transmit the EPDCCH scattered over a plurality of PRB pairs to obtain a frequency diversity gain, i.e., a distributed EPDCCH. For the situation that the base station sends the local EPDCCH, because the CSI information is relatively accurate, 256QAM can be used for further improving the downlink peak rate; for the situation that the base station sends the distributed EPDCCH, the CSI information is generally not very accurate, and the MCS table of the existing LTE standard can provide good performance.

The present application proposes to determine an MCS table for DCI use according to (E) a type (localized or distributed) of PDCCH. Specifically, the candidate EPDCCH configuring the localized EPDCCH set may use a new MCS table supporting 256QAM, that is, one of an MCS table using the existing LTE standard or an MCS table supporting 256QAM may be configured through higher layer signaling; whereas alternative EPDCCH in the distributed EPDCCH set use existing MCS tables. When a base station schedules downlink data transmission, the type (local or distributed) of the EPDCCH is selected according to the downlink state of the UE, and the MCS table is selected according to the method of the application to set the MCS domain in the DCI. Correspondingly, after the UE blindly detects an EPDCCH, the MCS domain in the DCI is analyzed according to the type (local or distributed) of the EPDCCH according to the method of the application to obtain the modulation mode and TBS scheduled by the base station.

In LTE release 11, it is supported to configure 2 EPDCCH sets for one UE. And, for the downlink transmission mode 10, the RE mapping and QCL configuration of each EPDCCH set are consistent with one RE mapping and QCL configuration of the PDSCH. For each PDSCH RE mapping and QCL configuration, its physical layer transmission technology for may be different, and correspondingly its link state. For example, the SINR may be higher with JT than with CS/CB, so that it is possible to use an MCS table supporting 256QAM when JT is used, and only adapt to use the existing MCS table when CS/CB is used. Thus, the EPDCCH set and the link state when the PDSCH is transmitted may have a certain correspondence.

The application proposes that each EPDCCH set of the UE can be respectively configured to use different MCS tables, namely when configuring parameters of the EPDCCH set, the UE is further configured to use one of the MCS tables of the existing LTE standard or the MCS tables supporting 256 QAM. When a base station schedules downlink data transmission, DCI information is transmitted on one alternative EPDCCH of one EPDCCH set of UE, and an MCS domain in the DCI is set according to an MCS table configured by the selected EPDCCH set. Correspondingly, after blind detection of one (E) PDCCH, the UE determines the MCS table according to the EPDCCH set to which the PDCCH belongs, and analyzes the MCS information in the DCI.

In LTE release 10, to support the eICIC technology, downlink subframes of a cell may be divided into two sets, and channel states of the two sets are different. For example, as shown in fig. 4, the subframe set in which the ABSF is configured for the macro base station, that is, the interference from the macro base station on the small cell is small, so the SINR of the UE may be large, and it may be suitable for adopting a 256QAM modulation scheme; for the other subframe sets, the macro base station sends downlink control and downlink data, so the SINR of the UE is relatively small, and the 256QAM modulation scheme may not be supported.

The network can divide the downlink sub-frame into a plurality of sets, for example, the interference degree of different downlink sub-frame sets is different; and configuring an MCS table used by the DCI for scheduling downlink data transmission for each downlink subframe set. If a new table is defined for 256QAM, the UE is configured to adopt an MCS table in the existing LTE version or a new MCS table supporting 256QAM according to the SINR condition of each downlink subframe set. If the long MCS table is defined, the method configures the UE to select the offset value v of the MCS index from the long MCS table according to the SINR condition of each downlink subframe set. After receiving the configuration information of the MCS tables of different subframe sets, the UE analyzes the modulation mode and TBS scheduled by the base station according to the MCS table configured by the network to the subframe set when detecting the DCI format of the scheduling downlink transmission in one subframe set.

The application also provides user terminal equipment which can be used for implementing the downlink transmission method. The specific structure of the user terminal device in the present application includes: a CQI information measuring and reporting unit, a downlink scheduling information receiving unit and a downlink data receiving and processing unit.

The CQI information measuring and reporting unit is used for measuring and reporting the CQI information of the downlink channel quality indication to the base station; here, the UE may report the above CQI information according to a backward compatible CQI table or a CQI table supporting 256QAM modulation.

And the downlink scheduling information receiving unit is used for receiving the downlink scheduling information sent by the base station.

A downlink data receiving and processing unit, configured to correspondingly receive and process downlink data sent by the base station according to MCS information in DCI included in the downlink scheduling information; here, the UE may process the MCS information according to a backward compatible MCS table or an MCS table supporting 256QAM modulation.

As can be seen from the above specific implementation of the present application, a CQI table and an MCS table supporting 256QAM transmission may be generated, and a CQI/MCS table that selectively uses the existing LTE standard or a CQI/MCS table supporting 256QAM according to a link state of a UE is supported, so as to optimize performance of downlink transmission.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A downlink transmission method comprises the following steps:

UE measures and reports downlink channel quality indication CQI information to a base station; wherein the UE reports the CQI information according to a backward compatible CQI table or a CQI table supporting 256QAM modulation; the CQI table is configured according to a subframe set and/or a CSI process;

the UE receives downlink scheduling information sent by the base station and correspondingly receives and processes downlink data sent by the base station according to Modulation Coding Scheme (MCS) information in Downlink Control Information (DCI) in the downlink scheduling information; wherein the UE processes the MCS information according to a backward compatible MCS table or an MCS table supporting 256QAM modulation; when the UE supports 256QAM, if the detected DCI format is a normal DCI format, determining to use an MCS table supporting 256QAM or a backward compatible MCS table according to a high-level signaling when the MCS information is processed; if the detected DCI format is a regression DCI format, a backward compatible MCS table is used when the MCS information is processed.

2. The method of claim 1, wherein the CQI table supporting 256QAM modulation is:

3. The method of claim 1, wherein the CQI table supporting 256QAM modulation is:

4. The method of claim 1, wherein the CQI table supporting 256QAM modulation is: adding a 256QAM modulated CQI entry in the backward compatible CQI table.

5. The method of claim 4, wherein when the UE reports the CQI information according to a CQI table supporting 256QAM modulation, the method further comprises:

6. A method according to any one of claims 1 to 5, characterized in that the method further comprises: the UE receiving base station respectively configures a CQI table used by a corresponding subframe set for each subframe set of the UE;

7. The method of claim 6, wherein the CQI table used by each subframe set of the UE is configured according to the SINR condition of the corresponding subframe set.

8. A method according to any one of claims 1 to 5, characterized in that the method further comprises: the method comprises the steps that UE receives a CQI table used by a corresponding CSI process which is respectively configured for each CSI process of the UE by a base station;

9. A method according to any one of claims 1 to 5, characterized in that the method further comprises: the method comprises the steps that the UE receives a CQI table which is respectively configured by a base station for each CSI process and each subframe set of the UE and used by each corresponding CSI process and each corresponding subframe set;

10. A method according to any one of claims 1 to 5, characterized in that the method further comprises: and the UE receives configuration information sent by the base station and is used for configuring the CQI table supporting 256QAM modulation or a backward compatible CQI table to report the CQI information.

11. The method of claim 1, wherein the MCS table supporting 256QAM modulation is:

and/or, in the backward compatible MCS table, removing a plurality of 64QAM modulated MCS items with the highest coding rate, and correspondingly adding 256QAM modulated MCS items;

12. The method of claim 1, wherein the MCS table supporting 256QAM is:

13. The method of claim 1, wherein the MCS table supporting 256QAM modulation is: adding a 256QAM modulated MCS entry in the backward compatible MCS table.

14. The method of claim 13, wherein when the UE processes the MCS information according to an MCS table supporting 256QAM modulation, the method further comprises:

15. The method according to any of claims 11 to 14, wherein after receiving the downlink scheduling information, the UE further comprises: using the MCS table corresponding to the RE mapping and QCL configuration of the PDSCH indicated by the downlink scheduling information as the MCS table used when processing the MCS information; wherein, the MCS table corresponding to each RE mapping and QCL configuration of the PDSCH is pre-configured for the base station.

16. The method according to any of claims 11 to 14, wherein after receiving the downlink scheduling information, the UE further comprises: and (E) PDCCH used for bearing the downlink scheduling information and detected by the UE is located in an MCS table used when the USS or CSS determines to process the MCS information.

17. The method according to any of claims 11 to 14, wherein after receiving the downlink scheduling information, the UE further comprises: and using the MCS table corresponding to the aggregation level of the (E) PDCCH for bearing the downlink scheduling information as the MCS table used for processing the MCS information.

18. The method of any one of claims 11 to 14, wherein the MCS table used in processing the MCS information is determined according to whether the type of the (E) PDCCH is localized or distributed.

19. The method according to any of claims 11 to 14, wherein after receiving the downlink scheduling information, the UE further comprises: taking an MCS table corresponding to an EPDCCH set where the EPDCCH for bearing the downlink scheduling information is located as an MCS table used when the MCS information is processed; wherein, the MCS table corresponding to each EPDCCH set of the UE is pre-configured for the base station.

20. A method according to any one of claims 11 to 14, characterized in that the method further comprises: dividing downlink subframes into a plurality of sets, and configuring a MCS table used by DCI (Downlink control information) for scheduling downlink data transmission for each downlink subframe set;

21. A user terminal device, UE, comprising: a channel quality indicator CQI information measuring and reporting unit, a downlink scheduling information receiving unit and a downlink data receiving and processing unit;

the CQI information measuring and reporting unit is used for measuring and reporting the CQI information of the downlink channel quality indication to the base station; wherein the UE reports the CQI information according to a backward compatible CQI table or a CQI table supporting 256QAM modulation; the CQI table is configured according to a subframe set and/or a CSI process;

the downlink data receiving and processing unit is configured to correspondingly receive and process downlink data sent by the base station according to Modulation and Coding Scheme (MCS) information in Downlink Control Information (DCI) included in the downlink scheduling information; wherein the UE processes the MCS information according to a backward compatible MCS table or an MCS table supporting 256QAM modulation; when the UE supports 256QAM, if the detected DCI format is a normal DCI format, determining to use an MCS table supporting 256QAM or a backward compatible MCS table according to a high-level signaling when the MCS information is processed; if the detected DCI format is a regression DCI format, a backward compatible MCS table is used when the MCS information is processed.

22. The UE of claim 21, wherein the CQI table supporting 256QAM modulation is:

23. The UE of claim 21, wherein the CQI table supporting 256QAM modulation is:

24. The UE of claim 21, wherein the CQI table supporting 256QAM modulation is: adding a 256QAM modulated CQI entry in the backward compatible CQI table.

25. The UE of claim 24, wherein when the UE reports the CQI information according to a CQI table supporting 256QAM modulation, the CQI information measuring and reporting unit further comprises:

26. The UE according to any of claims 21 to 25, wherein the CQI information measuring and reporting unit further comprises: the UE receiving base station respectively configures a CQI table used by a corresponding subframe set for each subframe set of the UE;

27. The UE of claim 26, wherein the CQI table used by each subframe set of the UE is configured according to the SINR of the corresponding subframe set.

28. The UE according to any of claims 21 to 25, wherein the CQI information measuring and reporting unit further comprises: the method comprises the steps that UE receives a CQI table used by a corresponding CSI process which is respectively configured for each CSI process of the UE by a base station;

29. The UE according to any of claims 21 to 25, wherein the CQI information measuring and reporting unit further comprises: the method comprises the steps that the UE receives a CQI table which is respectively configured by a base station for each CSI process and each subframe set of the UE and used by each corresponding CSI process and each corresponding subframe set;

30. The UE according to any of claims 21 to 25, wherein the CQI information measuring and reporting unit further comprises: and the UE receives configuration information sent by the base station and is used for configuring the CQI table supporting 256QAM modulation or a backward compatible CQI table to report the CQI information.

31. The UE of claim 21, wherein the MCS table supporting 256QAM modulation is:

32. The UE of claim 21, wherein the MCS table supporting 256QAM is:

33. The UE of claim 21, wherein the MCS table supporting 256QAM modulation is: adding a 256QAM modulated MCS entry in the backward compatible MCS table.

34. The UE of claim 33, wherein when the UE processes the MCS information according to an MCS table supporting 256QAM modulation, the CQI information measuring and reporting unit further comprises:

35. The UE according to any of claims 31 to 34, wherein the downlink data receiving and processing unit further comprises: after receiving the downlink scheduling information, using an MCS table corresponding to RE mapping and QCL configuration of the PDSCH indicated by the downlink scheduling information as an MCS table used for processing the MCS information; wherein, the MCS table corresponding to each RE mapping and QCL configuration of the PDSCH is pre-configured for the base station.

36. The UE according to any of claims 31 to 34, wherein the downlink data receiving and processing unit further comprises: and after receiving the downlink scheduling information, determining an MCS table used when the MCS information is processed according to (E) PDCCH (physical downlink control channel) which is detected by the UE and used for bearing the downlink scheduling information and is positioned in the USS or the CSS.

37. The UE according to any of claims 31 to 34, wherein the downlink data receiving and processing unit further comprises: and after receiving the downlink scheduling information, using an MCS table corresponding to the aggregation level of the (E) PDCCH for bearing the downlink scheduling information as the MCS table used for processing the MCS information.

38. The UE of any of claims 31 to 34, wherein the downlink data receiving and processing unit determines an MCS table to be used for processing the MCS information according to whether the type of the (E) PDCCH is localized or distributed.

39. The UE according to any of claims 31 to 34, wherein the downlink scheduling information receiving unit further comprises: after receiving the downlink scheduling information, taking an MCS table corresponding to an EPDCCH set where the EPDCCH for bearing the downlink scheduling information is located as an MCS table used when the MCS information is processed; wherein, the MCS table corresponding to each EPDCCH set of the UE is pre-configured for the base station.

40. The UE according to any of claims 31 to 34, wherein the downlink scheduling information receiving unit further comprises: dividing downlink subframes into a plurality of sets, and configuring a MCS table used by DCI (Downlink control information) for scheduling downlink data transmission for each downlink subframe set;

the downlink data receiving and processing unit further comprises: and after receiving the downlink scheduling information, using the MCS table used by the DCI information as an MCS table used for processing the MCS information.