WO2018214085A1

WO2018214085A1 - Method for transmitting downlink signal, and base station

Info

Publication number: WO2018214085A1
Application number: PCT/CN2017/085819
Authority: WO
Inventors: 杨敬; 吴和兵
Original assignee: 华为技术有限公司
Priority date: 2017-05-25
Filing date: 2017-05-25
Publication date: 2018-11-29

Abstract

The embodiments of the present application relate to a method for transmitting a downlink signal, and a base station. The method involves: a base station selecting one logical port from among multiple logical ports corresponding to a physical downlink control channel (PDCCH); and the base station transmitting, on the selected logical port, a downlink control signal to a terminal device. The embodiments of the present application improve the gain of an antenna and realize multi-user space division multiplexing, and are applicable to any type of base station.

Description

Method for transmitting downlink signal and base station

Technical field

The embodiments of the present application relate to the field of communications technologies, and in particular, to transmitting downlink signals.

Background technique

Massive Multiple-Input Multiple-Output (Massive MIMO) technology, also known as large-scale antenna technology.

In the case of large-scale antenna technology, especially in the case of adaptive beamforming (BF) and multi-user beamforming, the capacity and coverage of the Physical Downlink Shared Channel (PDSCH) Performance such as range can be significantly improved. Especially in the Time Division Duplexing (TDD) system, for N transmit antennas, BF technology can obtain up to 10*log10(N) array gain on coverage by channel reciprocity, and more The user's capacity gain is also significantly improved, and the space multiplexing gain of up to N users can be obtained in the capacity.

The PDSCH is enhanced in coverage and capacity, and new requirements are imposed on the coverage and capacity of the Physical Downlink Control Channel (PDCCH). However, in the existing communication protocol, for example, in the existing Long Term Evolution (LTE) protocol, the traditional control channel is transmitted by using transmit diversity, and is based on the cell common reference signal (Cell). Reference Signal (CRS), also known as cell common pilot, performs channel estimation and demodulation and decoding using Multiple-Input Multiple-Output (MIMO) technology. Therefore, if the PDCCH performs transmit diversity according to the conventional Space Frequency Block Code (SFBC) technology, the gain of the Massive MIMO on the array cannot be obtained, and thus the coverage and capacity of the PDCCH are difficult to be improved. At the same time, since the existing diversity transmission mechanism simulates multiple SFBC signal transmissions on multiple logical antennas, there is interference between multiple signals, and thus space division multiplexing of multiple users cannot be realized.

Summary of the invention

The embodiment of the present application provides a method for transmitting a downlink signal and a base station, which solves the problem that the existing SFCB technology is difficult to implement PDCCH coverage and capacity enhancement in a Massive MIMO scenario.

In a first aspect, an embodiment of the present application provides a method for transmitting a downlink control signal. The base station selects one logical port among the plurality of logical ports corresponding to the physical downlink control channel PDCCH. The base station transmits a downlink control signal to the terminal device on the selected one of the logical ports.

In a second aspect, an embodiment of the present application provides a base station. The base station includes a processor and a transmitter. The processor is configured to select one logical port among the multiple logical ports corresponding to the physical downlink control channel PDCCH. The transmitter is configured to transmit a downlink control signal to the terminal device on the selected one of the logical ports.

The embodiment of the present application transmits a downlink control signal by selecting a logical port on the PDCCH, as opposed to In the prior art, all the logical ports transmit downlink control signals, and the PDCCH coverage and capacity are enhanced.

In one example, before the transmitting the downlink control signal, the base station includes: determining, by the base station, that the user equipment is in a single narrow beam coverage.

In an example, the downlink control signal includes a downlink control signal sequence s0, s1, where the transmitting downlink control signal is specifically: the base station aggregates the downlink control signal sequence s0, s1 to the single narrow beam corresponding The logic antenna is launched on the antenna.

In one example, the downlink control signal sequence s0, s1 satisfies:

Wherein, W _{Boost, X} is a weight of a single narrow beam in which the user equipment is located; s ₀ ^* is a conjugate of the s ₀ , s ₁ ^* is a conjugate of the s ₁ ; H ₁ is a transmission The channel matrix of s ₁ , H ₀ ^H is a conjugate transposed matrix of a channel matrix in which the s ₀ is transmitted, and γ is a normalization factor.

In one example, the normalization factor

In an example, before the transmitting the downlink control signal to the terminal device, the method includes: the base station transmitting a cell common reference signal CRS.

In an example, the base station transmits a cell common reference signal CRS, specifically: the base station transmits a wide beam CRS signal on a first logical transmit antenna, and transmits a plurality of narrow beam synthesis on a second logical transmit antenna. A virtual wide beam CRS signal.

In one example, the weight of the CRS signal of one virtual wide beam synthesized by the plurality of narrow beams,

Wherein, W _{host0 is} a weight of a virtual wide beam fused by M narrow beams, W _{Boost, M-1} is a weight of the Mth narrow beam, and M is a number of narrow beams.

In one example, the wide beam CRS signal is a 65 degree wide beam CRS signal.

In a third aspect, an embodiment of the present application provides a method for transmitting a downlink control signal. The method includes: transmitting, by the base station, a corresponding downlink control signal to each user equipment in the first part of the user equipments of the plurality of user equipments on the first logical port of the plurality of logical ports corresponding to the physical downlink control channel PDCCH; The base station uses the same time-frequency domain resource as the first logical port on the second logical port of the multiple logical ports of the PDCCH, and each user in the second part of the user equipment of the multiple user equipments The devices respectively transmit corresponding downlink control signals.

In a fourth aspect, an embodiment of the present application provides a base station. The base station includes a transmitter and a processor. The transmitter is configured to respectively send a corresponding downlink control signal to each user equipment in the first part of the user equipments of the plurality of user equipments on the first logical port of the plurality of logical ports corresponding to the physical downlink control channel PDCCH. The processor is configured to determine a time-frequency domain resource of a second logical port of the multiple logical ports of the PDCCH, and the time-frequency domain resource of the second logical port is the same as the time-frequency domain resource of the first logical port . The transmitter is further configured to send, on a second logical port of the multiple logical ports of the PDCCH, respective downlink control signals to each user equipment in the second part of the user equipments of the multiple user equipments.

In the embodiment of the present application, the downlink control signal is transmitted by using the same time-frequency domain resource on multiple logical ports, thereby implementing space division multiplexing of multiple users.

In one example, the base station determines that channel conditions of the plurality of user equipments respectively reach a channel threshold, and the base station determines that the plurality of user equipments are respectively in a plurality of different single narrow beam coverage ranges.

In an example, the base station uses a plurality of different single narrow beams to transmit respective downlink control signals to each of the plurality of user equipments.

In an example, the downlink control signal sent by the base station to the first part of the user equipment includes a downlink control signal sequence s ₀ (k), and the downlink control signal sent by the base station to the second part of the user equipment includes a downlink control signal sequence s ₁ (k); the downlink control signal sequence s ₀ (k), s ₁ (k) satisfies:

Where N is the number of the plurality of user equipments, W _{Boost, X} is the weight of the kth narrow beam; s ₀ ^* (k) is the conjugate of the s ₀ (k), s ₁ ^* (k Is a conjugate of the s ₁ (k); H ₁ (k) is a channel matrix for transmitting the s ₁ (k), and H ₀ ^H (k) is a total of the transmission of the s ₀ (k) channel matrix Yoke transpose matrix.

In a fifth aspect, an embodiment of the present application provides a method for transmitting a downlink control signal. The method includes the base station determining that the user equipment is in a plurality of remote distributed antenna coverage areas. The base station transmits a downlink control signal on a physical downlink control channel PDCCH corresponding to each of the plurality of remote antennas.

In a sixth aspect, an embodiment of the present application provides a base station. The base station includes a processor and a transmitter. The processor is configured to determine that the user equipment is in a plurality of remote distributed antenna coverage areas. The transmitter is configured to transmit a downlink control signal on a physical downlink control channel PDCCH corresponding to each of the plurality of remote antennas.

The embodiment of the present application implements PDCCH space division multiplexing in a distributed antenna scenario.

In one example, the downlink control signal includes a downlink control signal sequence s ₀ (k-1), s ₁ (k-1), and the s ₀ (k-1), s ₁ (k-1) satisfy:

Where K is the number of the remote distributed antennas, s ₀ ^* (k-1) is the conjugate of the s ₀ (k-1), and s ₁ ^* (k-1) is the s ₁ Conjugation of (k-1); H ₁ (k-1) is a channel matrix for transmitting the s ₁ (k-1), and H ₀ ^H (k-1) is for transmitting the s ₀ (k-1) Conjugate transposed matrix of the channel matrix.

In one example, prior to transmitting the downlink control signal, the base station transmits a cell common reference signal CRS.

In an example, the base station transmits a cell common reference signal CRS, specifically: transmitting a wide beam CRS signal by a wide coverage antenna of the base station, and transmitting a narrow beam CRS signal by the distributed remote antenna.

In the embodiment of the present application, the downlink control signal is transmitted by selecting one logical port of multiple logics corresponding to the PDCCH, and the coverage of the PDCCH user is greatly improved. The embodiment of the present application implements space division multiplexing of multiple users by transmitting downlink control signals by using the same time-frequency domain resources on multiple logical ports.

DRAWINGS

FIG. 1 is a flowchart of a method for transmitting a downlink control signal according to an embodiment of the present application;

2 is a CRS signal pattern of wide and narrow beam fusion according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a downlink control signal according to an embodiment of the present application;

FIG. 4 is a flowchart of another method for transmitting a downlink control signal according to an embodiment of the present application;

FIG. 5 is a flowchart of still another method for transmitting a downlink control signal according to an embodiment of the present application;

FIG. 6 is a block diagram of a base station according to an embodiment of the present application;

FIG. 7 is a block diagram of another base station according to an embodiment of the present application;

FIG. 8 is a block diagram of still another base station according to an embodiment of the present application.

detailed description

The technical solutions of the embodiments of the present application will be described below with reference to the accompanying drawings.

Cell-specific reference signals (CRS), also known as common reference signals, or common pilots. The CRS can map multiple physical antennas into two logical antennas or four logical antennas by means of virtual antenna mapping weighting.

The following is an example in which the CRS can map multiple physical antennas into two logical antennas by means of virtual antenna mapping weighting.

In the Massive MIMO scenario, in order to consider reducing the overhead of the common pilot CRS, for the CRS pilots of the two logical antennas, the CRS beam is usually weighted according to the following formula (1), thereby forming a fixed width. CRS signal.

In formula (1), Wcrs is the weight of the CRS signal; and the first column of the matrix Wcrs is the weight of the logical antenna 0 of the transmitting antenna, that is, the logical port 0 (port0), and the second column of the matrix Wcrs is logic Antenna 1 is the weight of logical port 1 (port1).

In one example, the transmit antenna array is an N-column dual-polarized antenna array.

It can be known from formula (1) that the CRS signal is weighted by the formula (1), and the SFBC transmission is performed by logical 2T, that is, two logical antennas, also referred to as two logical ports, thereby mapping the CRS signals with weights W _Crs . Go to the N-column physical antenna channel to transmit.

For the way of transmitting through two logical antennas, two resources corresponding to two adjacent subcarriers respectively The element (Resource Element, RE), that is, RE0 and RE1, transmits a PDCCH control signal as follows:

In formula (2), RE0 represents the 0th resource element of the two resource elements; RE1 represents the first resource element of the two resource elements; s ₀ represents the 0th PDCCH control signal; s ₁ represents the first PDCCH control signal; s ₁ ^* denotes a conjugate of a negative first PDCCH control signal, s ₀ ^* denotes a conjugate of a 0th PDCCH control signal; Port 0 denotes a logical port 0, that is, a logical antenna 0; and Port 1 denotes a logical port 1, that is, a logical antenna 1.

It can be known from formula (2) that the PDCCH control signal is transmitted through two logical antennas, that is, two logical ports port0 and port1, and the signals in the two logical antennas may cause mutual interference, thereby failing to achieve multi-user space division. use. Space-division multiplexing means that multiple users can simultaneously transmit resources through the air interface channel on the same time-frequency domain resource.

The following uses two logical antennas as an example to describe in detail how the base station provided by the embodiment of the present application transmits a downlink signal.

FIG. 1 is a flowchart of a method for transmitting a downlink signal according to an embodiment of the present application.

In step 101, the base station determines downlink channel information, that is, the base station determines the downlink channel matrix H, and the matrix is:

In an example, the base station obtains the downlink channel matrix H according to at least one of a recoding matrix indicator (PMI) and a channel quality indicator (CQI) fed back by the user equipment.

In another example, the base station obtains uplink channel information by using an uplink sounding reference signal (SRS), which is also referred to as an uplink pilot signal, and then obtains downlink channel information according to reciprocity of the uplink and downlink channels. Among them, SRS is used for estimation and quality feedback of the uplink channel.

Specifically, in LTE, when the uplink and downlink transmission time intervals are sufficiently short, the fading of the uplink channel and the downlink channel may be considered to be substantially the same, that is, the uplink and downlink channels have reciprocity. Based on this feature, the LTE base station can estimate the channel fading to be experienced by the downlink transmission signal by detecting the uplink transmission signal (such as the uplink reference signal), and thereby determine the downlink transmission parameter, thereby obtaining the downlink channel matrix H.

In step 102, the base station determines whether the user equipment is an edge user equipment or a user equipment with good signal conditions, and determines whether the user equipment is in a single narrow beam coverage or a wide beam coverage.

In an example, the base station calculates the ratio of the uplink power of the user equipment in the wide beam and the narrow beam. If the ratio is greater than the threshold, the user equipment is in the wide beam coverage; otherwise, the user equipment is in the Narrow beam coverage. In step 103, the base station transmits a wide-beam CRS signal on Port0, and transmits a virtual wide-beam CRS signal synthesized by a plurality of narrow beams on Port1.

It can be understood by those skilled in the art that the foregoing step 103 and step 101 have no sequential relationship, that is, step 103 may be performed first and then step 101 and step 102 may be performed. Step 101 and step 102 may be performed first and then step 103 is performed.

In one example, the base station transmits a CRS signal in the following manner:

Port0 is the transmit port of the wide beam; W _host0 is the weight of Port0, and W _host0 is the wide beam weight, such as the traditional 65 degree wide beamforming weight; S _p0 is the CRS signal sequence transmitted on Port0 Port1 is the transmitting port of the virtual wide beam fused by multiple narrow beams, W _host1 is the weight of Port1; S _p1 is the sequence of CRS signals transmitted on Port1; M is the number of narrow beams, and W _{host0 is} composed of M The weight of the virtual wide beam into which the narrow beam is fused, W _{Boost, M-1} is the weight of the Mth narrow beam.

In one example, W _Boost0 , W _Boost1 , W _Boost2 ... W _{Boost, M-1} is a narrow beam shaping weight that points to a different azimuth, which can be generated by current general criteria, such as Bischev criterion.

2 is a CRS signal pattern of a wide and narrow beam fusion provided by an embodiment of the present application, that is, a CRS signal diagram represented by the formula (4).

In FIG. 2, CRS Port0 is a virtual wide beam CRS signal pattern synthesized by four narrow beams, that is, a pattern of CRS signals transmitted by logical port 0; CRS Port1 is a wide beam CRS pattern, that is, a CRS transmitted by logical port 1. The direction of the signal.

It should be noted that the number of virtual wide-beam CRS signals synthesized by multiple narrow beams in the embodiment of the present application is not limited to four, and FIG. 2 only takes a virtual wide-beam CRS signal synthesized by four narrow beams as an example.

As can be seen from Fig. 2, the CRS Port1 pattern (i.e., the virtual wide beam pattern synthesized by the narrow beam) is significantly enhanced in coverage and capacity relative to the CRS Port0 pattern (i.e., the wide beam pattern). However, the CRS Port0 pattern may form three heart-shaped recessed regions with respect to the CRS Port1 pattern, and the heart-shaped recessed regions may be disadvantageous for coverage, and the embodiment of the present application compensates for the wide-beam CRS pattern of the CRS Port1. The coverage of the three heart-shaped recessed areas ensures that the user equipment in the heart-shaped recessed area can correctly receive the CRS signal.

In step 104, if it is determined in step 102 that the user equipment is in the edge coverage, and the user equipment is in a single narrow beam coverage, the base station selects one logical port among the multiple logical ports corresponding to the physical downlink control channel PDCCH. For example, the physical downlink control channel PDCCH corresponds to two logical ports, and the base station arbitrarily selects the first logical port or the second logical port. The base station transmits a downlink control signal to the user equipment on the selected one of the logical ports.

In one example, the downlink control signal sequence s0, s1 satisfies:

In one example, the normalization factor

Specifically, the base station transmits on the two resource elements RE0 and RE1 corresponding to two adjacent subcarriers of the physical downlink control channel PDCCH according to the following manner:

Wherein, W _{Boost, X} is a weight of a single narrow beam in which the user equipment is located, and the weight W _{Boost, X} may be generated by a general narrow beam weight design criterion, for example, generated by a Chebyshev criterion; s ₀ is The PDCCH control signal sequence 0, s ₁ transmitted by the base station is a PDCCH control signal sequence 1 transmitted by the base station, s ₀ ^* is a conjugate of the control signal sequence 0, and s ₁ ^* is a conjugate of the control signal sequence 1; ₁ is the channel of the port Port1, H ₀ ^H is a conjugate transposed matrix of the channel transmitting the port Port0, and γ is a normalization factor.

Normalization factor

In the case, the above formula (5) can be converted into:

Wherein, W _{Boost, X} is a weight matrix of a single narrow beam in which the user equipment is located, the weight matrix W _{Boost, X} may be generated by a Chebyshev criterion; s ₀ is a sequence of PDCCH control signals transmitted by the base station 0, s ₁ The PDCCH control signal sequence 1, s ₀ ^* transmitted for the base station is the conjugate of the s ₀ , s ₁ ^* is the conjugate of the s ₀ ; H ₀ is the channel matrix 0 of the transmission control signal, and H ₁ is the transmission control matrix channel signals 1, ^H ₀ H is a channel matrix of transmission of the control signal 0 conjugate transpose matrix.

Equation (6) is equivalent to:

Wherein, eNB Ant0 is physical antenna 0, eNB AntN-1 is physical antenna N-1; X ₀₀ is a signal transmitted by physical antenna 0 on resource RE0, and X ₀₁ is a signal transmitted by physical antenna 0 on resource RE1; X _{N -1,0} is the signal transmitted by the physical antenna N-1 on the resource RE0, and X _N-1,1 is the signal transmitted by the physical antenna N-1 on the RE1.

Equation (7) indicates that the base station transmits PDCCH control on the resource elements RE0 and RE1 corresponding to two adjacent subcarriers of the physical downlink control channel PDCCH according to the formula (6) on the right side of the equation (7). signal.

It can be known from the above formulas (6) and (7) that the power of the physical antenna of the PDCCH is aggregated to a single narrow beam W _{Boost, X} , where the user equipment is located, and the maximum power gain can be obtained; wherein M is a narrow beam. The total number.

3 is a direction diagram of a control signal PDCCH according to an embodiment of the present application, and FIG. 4 is a PDCCH signal pattern of four narrow beams and one wide beam.

It should be noted that the number of narrow beams is not limited to four, and FIG. 3 only takes the PDCCH signal pattern of four narrow beams as an example.

In FIG. 3, the weights of the control signals of the four narrow beams are the same as the weights of the CRS Port1 beams in FIG. 2 (ie, the virtual wide beams synthesized by the four narrow beams).

It can be seen from Fig. 3 that the overlapping regions of the four narrow beams are small, and therefore, a single narrow beam has a strong signal advantage. When the user equipment enters any narrow beam area, the base station transmits a PDCCH control signal on the port Port0 according to the formula (6), thereby concentrating and transmitting the power of the PDCCH control signal. The PDCCH control signal is transmitted on the narrow beam, and a gain of approximately 6 dB can be obtained with respect to transmitting the PDCCH control signal on the wide beam. In addition, since the overlapping areas of the four narrow beams are small, the isolation between the narrow beams is sufficiently high. Therefore, four narrow beams can perform space division multiplexing of four user equipments, thereby realizing space division multiplexing of multiple users.

It can be seen that when the user equipment is in a single narrow beam coverage and the user equipment belongs to the edge user equipment, in order to increase the gain, the base station uses the resource elements RE0 and RE1 corresponding to the two adjacent subcarriers according to the formula (6). The method of transmitting the PDCCH control signal not only can obtain a large gain, but also the PDCCH coverage and capacity is enhanced (because the edge user can still obtain a sufficiently large gain), and also realizes multi-user space division multiplexing.

As explained in detail below, if the PDCCH control signal is transmitted in the manner of equation (6), the user equipment can correctly decode and demodulate.

The downlink PDCCH control signal received by the user equipment is:

Where [Y _RE0 Y _RE1 ] is a downlink PDCCH control signal matrix received by the user equipment, [H ₀ H ₁ ] is a channel matrix; γ is a power normalization factor,

And,

Wherein, Y _RE0 and Y _RE1 are downlink control signal vectors respectively received by the user equipment on resource elements RE0 and RE1 corresponding to two adjacent subcarriers; s ₀ is a sequence of PDCCH control signals transmitted by the base station, 0, s ₁ The PDCCH control signal sequence 1, s ₀ ^* transmitted for the base station is the conjugate of the control signal sequence 0, s ₁ ^* is the conjugate of the control signal sequence 1; H ₀ is the channel matrix 0, H of the transmission control signal ₁ is a channel matrix 1 for transmitting a control signal, and H ₀ ^H is a conjugate transposed matrix of a channel matrix 0 transmitting the control signal.

User equipment demodulates Y _RE0 , Y _RE1 , and obtains the signal

They are:

Where s ₀ is a control signal transmitted by the logic antenna 0,

a control signal 0 obtained by decoding the received signal for the user equipment; s ₁ is a control signal transmitted by the logic antenna 1,

A control signal 1 obtained by decoding a received signal for a user equipment. Y _RE0 and Y _RE1 are the downlink control signal vectors respectively received by the user equipment on the resource elements RE0 and RE1 corresponding to two adjacent subcarriers; Y ^H _RE0 and Y ^H _RE1 are respectively Y _RE0 and Y _RE1 a yoke transposed matrix; s ₀ is a PDCCH control signal sequence 0 transmitted by the base station, s ₁ is a PDCCH control signal sequence 1 transmitted by the base station, s ₀ ^* is a conjugate of the control signal sequence 0, and s ₁ ^* is the control The conjugate of the signal sequence 1; H ₀ is the channel matrix 0 of the transmission control signal, H ₁ is the channel matrix ₁ of the transmission control signal, and H ₀ ^H is the conjugate transposed matrix of the channel matrix 0 transmitting the control signal.

It can be seen from equations (11) and (12) that if the base station transmits a control signal according to the formula (6), the user equipment can decode and demodulate Y _RE0 and Y _RE1 to obtain

Demodulated

The PDCCH control signals s ₀ , s ₁ transmitted by the base station only change in amplitude, and the phase does not change, so the user equipment can perform normal demodulation.

In step 105, if it is determined in step 102 that the channel conditions of the N user equipments respectively reach the channel threshold, and the N user equipments are respectively covered by different single narrow beams, the base station is in the physical downlink control channel PDCCH. Corresponding downlink control signals are respectively transmitted to each of the first user equipments of the plurality of user equipments on the first logical port of the corresponding multiple logical ports. a base station at a plurality of logical ports of the PDCCH The second logical port transmits the corresponding downlink control signal to each user equipment in the second part of the user equipments of the plurality of user equipments by using the same time-frequency domain resource as the first logical port.

In one example, the downlink control signal transmitted by the base station to the first part of the user equipment includes a downlink control signal sequence s ₀ (k), and the downlink control signal transmitted by the base station to the second part of the user equipment includes a downlink control signal sequence s ₁ (k The downlink control signal sequence s ₀ (k), s ₁ (k) satisfies:

Where N is the number of the plurality of user equipments, W _{Boost, X} is the weight of the kth narrow beam; s ₀ ^* (k) is the conjugate of the s ₀ (k), s ₁ ^* (k Is a conjugate of the s ₁ (k); H ₁ (k) is a channel matrix for transmitting the s ₁ (k), and H ₀ ^H (k) is a total of the transmission of the s ₀ (k) channel matrix Yoke transpose matrix

Specifically, the base station transmits a PDCCH control signal according to the following formula (13) on two resource elements RE0 and RE1 corresponding to two adjacent subcarriers:

N is the number of user equipments, which is also the number of single narrow beams; W _{Boost, k} is the weight of the kth narrow beam, and s ₀ (k) and s ₁ (k) respectively represent the kth narrow beam in the The PDCCH control signal sequences transmitted on the resource elements RE0, RE1 corresponding to the adjacent subcarriers, that is, s ₀ (k) and s ₁ (k) represent the control signal sequence to be transmitted by the user on the kth beam; s ₀ ^* (k) is the conjugate of s ₀ (k), s ₁ ^* (k) is the conjugate of s ₁ (k); H ₀ (K) is the channel matrix for transmitting the s ₀ (k) signal, H ₁ ( K) is a channel matrix for transmitting the s ₁ (k) signal; H ₀ ^H (K) is a conjugate transposed matrix of H ₀ (K);

Is the channel of the kth narrow beam.

It can be seen from the formula (12) that since each beam can independently transmit a control signal of a single user, space division multiplexing is realized.

Equation (13) is equivalent to:

It can be seen from the formula (14) that, in the case that the channel conditions of the N user equipments are good, and are respectively in the case of N single narrow beams, the embodiment of the present application transmits the data to the N user equipments.

Multiply by its corresponding weight W _BOOST,K , and then seek the mean; and each user power is only

The total power is guaranteed to be constant.

In step 106, if it is determined in step 102 that the user equipment does not belong to step 104, it does not belong to step 105, that is, for other users, the base station transmits according to the existing SFBC mode:

It can be understood by those skilled in the art that the

above steps

104, 105, and 106 have no sequential relationship, and the base station performs one of the steps according to actual conditions. That is, in step 102, if the base station determines that the user equipment is in the edge coverage and the user equipment is in a single narrow beam coverage, step 104 is performed; if the base station determines the channel conditions of the multiple user equipments in step 102, If the multiple user equipments are respectively in different single narrow beam coverage areas, step 105 is performed. If the base station determines that the user equipment does not belong to the above two situations, step 106 is performed.

The following uses four logical antennas as an example to describe in detail how the base station provided by the embodiment of the present application transmits a downlink signal.

FIG. 4 is a flowchart of another downlink signal transmission method according to an embodiment of the present application.

In step 401, the base station determines downlink channel information, for example, the base station determines the downlink channel matrix H, and the matrix is:

In another example, the base station acquires uplink channel information by using the uplink pilot signal SRS, and then according to the uplink and downlink. The reciprocity of the channel, thereby obtaining downlink channel information. Among them, SRS is used for estimation and quality feedback of the uplink channel.

In step 402, the base station determines whether the user equipment is an edge user equipment or a user equipment with good signal conditions, and determines whether the user equipment is in a single narrow beam coverage or a wide beam coverage.

In an example, the base station calculates the ratio of the uplink power of the user equipment in the wide beam and the narrow beam. If the ratio is greater than the threshold, the user equipment is in the wide beam coverage; otherwise, the user equipment is in the Narrow beam coverage. In step 403, the base station transmits a wide beam CRS signal on Port0, a wide beam CRS signal on Port1, and a virtual wide beam CRS signal synthesized by multiple narrow beams on Port2, and multiple transmissions in Port3. A virtual wide beam CRS signal synthesized by a narrow beam.

It can be understood by those skilled in the art that the

above steps

403 and 401 have no sequential relationship, that is, step 403 may be performed first and then step 401 and step 402 may be performed. Step 401, step 402, and step 403 may be performed first.

Where W _host0 is the weight of the wide beam signal transmitted on Port0, such as the traditional 65 degree wide beamforming weight; S _p0 is the CRS signal sequence transmitted on Port 0; W _host1 is the width transmitted on Port 1 right beam signal value; S _p1 CRS signal sequence is transmitted on the Port1; W _host2 is the weight of a plurality of narrow beam synthesis virtual wide beam signal is transmitted on the Port2 value; S _p2 is transmitted on CRS Port2 Signal sequence; W _host3 is the weight of the virtual wide beam signal synthesized by multiple narrow beams transmitted on Port3; S _p3 is the CRS signal sequence transmitted on Port3; M is the number of narrow beams; W _host0 is M The weight of the virtual wide beam into which the narrow beams are merged, W _{Boost, M-1} is the weight of the Mth narrow beam.

In one example,

as well as

Both are narrow beamforming weights that point to different azimuths, which can be generated by current general criteria, such as the Chebyshev criterion.

In step 404, if it is determined in step 402 that the user equipment is in the edge coverage and the user equipment is in a single narrow beam coverage, the base station selects one logical port among the multiple logical ports corresponding to the physical downlink control channel PDCCH. For example, the physical downlink control channel PDCCH corresponds to four logical ports, and the base station arbitrarily selects the first logical port, or the second logical port or the third logical port or the fourth logical port. The base station transmits a downlink control signal to the user equipment on the selected one of the logical ports.

In one example, the base station transmits on the four resource elements RE0, RE1, RE2, and RE3 of the physical downlink control channel PDCCH as follows:

Wherein, eNB Ant0 is physical antenna 0, eNB AntN-1 is physical antenna N-1; X ₀₀ is a signal transmitted by physical antenna 0 on resource RE0, and X ₀₁ is a signal transmitted by physical antenna 0 on resource RE1; X _{N -1,0} is the signal transmitted by physical antenna N-1 on resource RE0, X _N-1,1 is the signal transmitted by physical antenna N-1 on RE1; X ₀₂ is the signal transmitted by physical antenna 0 on resource RE2 X ₀₃ is a signal transmitted by the physical antenna 3 on the resource RE1; X _{N-1, 2} is a signal transmitted by the physical antenna N-1 on the resource RE2, and X _{N-1, 3} is a physical antenna N-1 on the RE3 The transmitted signal.

In formula (18), W ⁰ _{Boost, X} is the first weight matrix of the narrow beam of the user equipment, W ¹ _{Boost, X} is the second weight matrix of the narrow beam corresponding to the user equipment; s ₀ is the PDCCH control transmitted by the base station The signal sequence 0, s ₁ is a PDCCH control signal sequence 1 transmitted by the base station, s ₂ is a PDCCH control signal sequence 2 transmitted by the base station, and s ₃ is a PDCCH control signal sequence 3 transmitted by the base station; s ₀ ^* is the control signal sequence 0 Conjugation, s ₁ ^* is the conjugate of the control signal sequence 1, s ₃ ^* is the conjugate of the control signal sequence 3; H ₀ is the channel matrix of the transmission control signal, and H ₁ is the channel for transmitting the control signal Matrix 1, H ₂ is a channel matrix 2 for transmitting control signals, H ₃ is a channel matrix ₃ for transmitting control signals; H ₀ ^H is a conjugate transposed matrix of channel matrix 0 for transmitting the control signals, and H ₁ ^H is transmission A conjugate transposed matrix of the channel matrix 1 of the control signal.

At step 405, if at step

Determining, in the case that the channel conditions of the N user equipments respectively reach the channel threshold, and the N user equipments are respectively covered by different single narrow beams, the base station is in the plurality of logical ports corresponding to the physical downlink control channel PDCCH A logical port is configured to transmit a corresponding downlink control signal to each of the user equipments of the first part of the plurality of user equipments. The base station uses the same time-frequency domain resource as the first logical port on the second logical port of the multiple logical ports of the PDCCH, and each user equipment in the second partial user equipment of the multiple user equipments , respectively transmitting corresponding downlink control signals.

In an example, the base station transmits the PDCCH control signal according to the following formulas (19) and (20) on the resource elements RE0, RE1, RE2, and RE3 corresponding to the four adjacent subcarriers:

N is the number of user equipments, and is also the number of single narrow beams; W ⁰ _{Boost, k} is the first weight of the kth narrow beam, W ¹ _{Boost, k} is the second weight of the kth narrow beam; ₀ (k), s ₁ (k), s ₂ (k), s ₃ (k) respectively indicate that the kth narrow beam is transmitted on the resource elements RE0, RE1, RE2, RE3 corresponding to the adjacent subcarriers PDCCH control signal sequence; s ₀ ^* (k) is a conjugate of s ₀ (k), s ₁ ^* (k) is a conjugate of s ₁ (k), and s ₂ ^* (k) is s ₂ (k) Conjugation, s ₂ ^* (k) is the conjugate of s ₂ (k); H ₀ (K) is the channel matrix for transmitting the s ₀ (k) signal, and H ₁ (K) is the signal for transmitting the s ₁ (k) The channel matrix, H ₂ (K) is the channel matrix for transmitting the s ₂ (k) signal, H ₃ (K) is the channel matrix for transmitting the s ₃ (k) signal; H ₀ ^H (K) is H ₀ (K) Conjugate transposed matrix, H ₁ ^H (K) is a conjugate transposed matrix of H ₁ (K); H ₂ ^H (K) is a conjugate transposed matrix of H ₂ (K); H ₃ ^H (K) A conjugate transposed matrix of H ₃ (K).

In step 406, if it is determined in step 402, the case where the user equipment does not belong to step 404 does not belong to the case of step 405, that is, for other users, the base station transmits according to the existing SFBC mode, as shown in the formula. (15).

It can be understood by those skilled in the art that the

above steps

404, 405, and 406 have no sequential relationship, and the base station performs one of the steps according to the actual situation. That is, in step 402, if the base station determines that the user equipment is in the edge coverage, and the user equipment is in a single narrow beam coverage, step 404 is performed; if the base station determines the channel conditions of the multiple user equipments in step 402, If the multiple user equipments are respectively in different single narrow beam coverages, step 405 is performed. If the base station determines that the user equipment does not belong to the above two situations, step 406 is performed.

The above solution, including the technical solutions of steps 101 to 106 shown in FIG. 1 and the technical solutions of steps 401 to 406 shown in FIG. 4, is suitable for any Massive MIMO antenna scenario.

In a Massive MIMO scenario consisting of distributed antennas, the base station can transmit downlink signals in the following manner, as will be explained in more detail below.

Assume that Massive MIMO consisting of distributed antennas includes a wide coverage antenna (wide coverage) and multiple remote distributed antennas (covering direction concentration).

In step 501, the base station determines downlink channel information, such as determining a downlink channel matrix. The channel matrix H can be referred to the formula (3) described above.

In an example, the base station indicates, according to a precoding matrix indicator fed back by the user equipment. At least one of a PMI) and a Channel Quality Indicator (CQI) obtains a downlink channel matrix H.

In another example, the base station acquires uplink channel information by using the uplink pilot signal SRS, and then obtains downlink channel information according to reciprocity of the uplink and downlink channels. Among them, SRS is used for estimation and quality feedback of the uplink channel.

In step 502, the base station transmits a wide beam CRS signal through the wide coverage antenna, and transmits a plurality of narrow beam CRS signals through multiple distributed remote antennas.

In step 503, the base station determines, according to the magnitude relationship between the power of the signal received by the wide coverage antenna and the power of the signal received by the plurality of distributed remote antennas, whether the user equipment is in a wide coverage antenna coverage or a distributed pull. Far antenna coverage.

Specifically, when the base station receives the downlink signal of the user equipment, if the power of the signal received by the base station through the wide coverage antenna is greater than the value of the power of the signal received through the distributed remote antenna exceeds the first threshold, the base station determines the user. The device is in a wide coverage antenna coverage; if the power of the signal received by the base station through the distributed remote antenna is greater than the value of the power of the signal received through the wide coverage antenna exceeds the second threshold, the base station determines that the user equipment is in a distributed pull Far antenna coverage.

It should be noted that the foregoing step 503 and step 501 have no sequential relationship, that is, step 503 may be performed first and then step 501 may be performed. You can also perform step 501 and then perform step 503.

In step 504, when the base station determines that the user equipment is in the distributed remote antenna coverage, and the current network load of the base station exceeds the load threshold, the base station follows the resource elements RE0 and RE1 corresponding to the two adjacent subcarriers. In the manner of equation (21), the downlink PDCCH control signal is transmitted:

Where K is the number of distributed antennas; s ₀ (k-1) and s ₁ (k-1) respectively represent resource elements RE0, RE1 corresponding to the adjacent subcarriers of the k-1th distributed antenna a sequence of PDCCH control signals transmitted on the upper; s ₀ ^* (k-1) is a conjugate of s ₀ (k-1), s ₁ ^* (k-1) is a conjugate of s ₁ (k-1); H _{BOOST K-1} is a channel matrix for transmitting s ₀ (k-1) signals and s ₁ (k-1) signals; H ^H _{BOOST, K-1} is a conjugate transposed matrix of H _{BOOST, K-1} .

It can be known from equation (19) that the base station transmits on the resource element RE0 through the antenna 0 of a plurality of distributed antennas.

Fire on resource element RE1

The base station transmits on the resource element RE0 through the antenna 1 of a plurality of distributed antennas

Fire on resource element RE1

It can be seen from the above formula (21) that each distributed antenna can independently transmit one user's PDCCH, thus implementing space division multiplexing.

In step 506, if the base station determines that the current network load does not exceed the threshold, the base station transmits according to the existing SFBC mode. For details, refer to formula (15).

FIG. 6 is a block diagram of a base station according to an embodiment of the present application. The base station 600 includes a processor 610 and a transmitter 620.

The processor 610 is configured to select one logical port among the multiple logical ports corresponding to the physical downlink control channel PDCCH.

The transmitter 620 is configured to transmit a downlink control signal to the terminal device on the selected one of the logical ports.

In one example, the processor 610 is further configured to determine that the user equipment is in a single narrow beam coverage.

In one example, the processor 610 is specifically configured to: the downlink control signal includes a downlink control signal sequence s0, s1, where the processor is specifically configured to aggregate the downlink control signal sequence s0, s1 The transmission is performed on a logical antenna corresponding to a single narrow beam.

In one example, the

The downlink control signal sequence s0, s1 satisfies:

_Wherein, W _{Boost, X} is a single narrow beam weights user equipment is located; s ₀ s ₀ ^* is the conjugate, s ₁ ^* is the conjugate of s _1; ₁ H is a transmission The channel matrix of s ₁ , H ₀ ^H is the conjugate transposed matrix of the channel matrix for transmitting s ₀ , and γ is the normalization factor.

In one example, the normalization factor

In one example, the transmitter is also for transmitting a cell common reference signal CRS.

In one example, the transmitter is further configured to transmit a wide beam CRS signal on the first logical transmit antenna and a virtual wide beam CRS signal synthesized from the plurality of narrow beams on the second logical transmit antenna.

In one example, the wide beam CRS signal is a 65 degree wide beam CRS signal.

FIG. 7 is a block diagram of another base station provided by an embodiment of the present application. The base station 700 includes a transmitter 710 and a processor 720.

The transmitter 710 is configured to separately send a corresponding downlink control signal to each user equipment in the first part of the user equipments of the plurality of user equipments on the first logical port of the multiple logical ports corresponding to the physical downlink control channel PDCCH.

The processor 720 is configured to determine a time-frequency domain resource of a second logical port of the multiple logical ports of the PDCCH, and a time-frequency domain resource of the second logical port and a time-frequency domain of the first logical port The resources are the same.

The transmitter 710 is further configured to send, on a second logical port of the multiple logical ports of the PDCCH, respective downlink control signals to each user equipment in the second part of the user equipments of the multiple user equipments.

In an example, the processor 720 is further configured to: determine that channel conditions of the multiple user equipments respectively reach a channel threshold, and the base station determines that the multiple user equipments are respectively in multiple different single narrow beam coverages. range.

In one example, the transmitter 710 is specifically configured to: use each of the multiple user equipments of the multiple user equipments to respectively transmit a corresponding downlink control signal by using a plurality of different single narrow beams.

In one example, the transmitter 710

The downlink control signal transmitted by the first part of the user equipment includes a downlink control signal sequence s ₀ (k), and the downlink control signal transmitted by the transmitter to the second part of the user equipment includes a downlink control signal sequence s ₁ (k); The control signal sequence s ₀ (k), s ₁ (k) satisfies:

FIG. 8 is a block diagram of still another base station according to an embodiment of the present application. Base station 800 includes a processor 810 and a transmitter 820.

The processor 810 is configured to determine that the user equipment is in a plurality of remote distributed antenna coverage areas.

The transmitter 820 is configured to transmit a downlink control signal on a physical downlink control channel PDCCH corresponding to each of the plurality of remote antennas.

In one example,

The downlink control signal includes a downlink control signal sequence s ₀ (k-1), s ₁ (k-1), and the s ₀ (k-1) and s ₁ (k-1) satisfy:

In one example, the transmitter 820 is also configured to transmit a cell common reference signal CRS.

In one example, the transmitter 820 transmits a cell common reference signal CRS, specifically: a CRS signal of a wide beam is transmitted by a wide coverage antenna of the base station, and a CRS signal of a narrow beam is transmitted by the distributed remote antenna.

A person skilled in the art should further appreciate that the elements and algorithm steps of the various examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both, in order to clearly illustrate hardware and software. Interchangeability, the composition and steps of the various examples have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the solution. Professionals can use different methods to implement the described functions for each specific application, but this implementation does not It should be considered beyond the scope of this application.

It will be understood by those skilled in the art that all or part of the steps of implementing the above embodiments may be performed by a program, and the program may be stored in a computer readable storage medium, which is non-transitory ( English: non-transitory) media, such as random access memory, read-only memory, flash memory, hard disk, solid state disk, magnetic tape (English: magnetic tape), floppy disk (English: floppy disk), CD (English: optical disc) And any combination thereof.

The above description is only a preferred embodiment of the present application, but the scope of protection of the present application is not limited thereto, and any person skilled in the art can easily think of changes or within the technical scope disclosed in the present application. Replacement should be covered by the scope of this application. Therefore, the scope of protection of the present application should be determined by the scope of protection of the claims.

Claims

A method for transmitting a downlink control signal, characterized in that the method comprises:

The base station selects one logical port among the multiple logical ports corresponding to the physical downlink control channel PDCCH;

The base station transmits a downlink control signal to the user equipment on the selected one of the logical ports.
The method according to claim 1, wherein before the transmitting the downlink control signal, the method comprises:

The base station determines that the user equipment is in a single narrow beam coverage.
The method according to claim 2, wherein the downlink control signal comprises a downlink control signal sequence s0, s1, and the transmitting downlink control signal is specifically: the base station sends the downlink control signal sequence s0, s1, The convergence is transmitted to the logical antenna corresponding to the single narrow beam.
The method according to claim 3, wherein the downlink control signal sequence s0, s1 satisfies:

Wherein, W Boost, X is a weight of a single narrow beam in which the user equipment is located; s 0 * is a conjugate of the s 0 , s 1 * is a conjugate of the s 1 ; H 1 is a transmission The channel matrix of s 1 , H 0 H is a conjugate transposed matrix of a channel matrix in which the s 0 is transmitted, and γ is a normalization factor.
The method of claim 4 wherein said normalization factor
The method according to any one of claims 1 to 5, wherein before the transmitting the downlink control signal to the terminal device, the method includes:

The base station transmits a cell common reference signal CRS.
The method according to claim 6, wherein the base station transmits a cell common reference signal CRS, specifically:

The base station transmits a wide beam CRS signal on a first logical transmit antenna and a virtual wide beam CRS signal synthesized from a plurality of narrow beams on a second logical transmit antenna.
The method according to claim 7, wherein the weight of the CRS signal of the one virtual wide beam synthesized by the plurality of narrow beams is

Wherein, W host0 is a weight of a virtual wide beam fused by M narrow beams, W Boost, M-1 is a weight of the Mth narrow beam, and M is a number of narrow beams.
The method according to claim 7 or 8, wherein the wide beam CRS signal is a 65 degree wide beam CRS signal.
A method for transmitting a downlink control signal, characterized in that the method comprises:

The base station transmits a corresponding downlink control signal to each user equipment in the first part of the user equipments of the plurality of user equipments on the first logical port of the plurality of logical ports corresponding to the physical downlink control channel PDCCH;

The base station uses the same time-frequency domain resource as the first logical port on the second logical port of the multiple logical ports of the PDCCH, and each of the second partial user equipments of the multiple user equipments The user equipment respectively transmits corresponding downlink control signals.
The method of claim 10 wherein said method comprises:

The base station determines that the channel conditions of the multiple user equipments respectively reach a channel threshold, and the base station determines that the multiple user equipments are respectively in a plurality of different single narrow beam coverage ranges.
The method according to claim 11, wherein the base station uses a plurality of different single narrow beams to transmit respective downlink control signals to each of the plurality of user equipments.
A method according to any one of claims 10 to 12, wherein said said

The downlink control signal transmitted by the base station to the first part of the user equipment includes a downlink control signal sequence s 0 (k), and the downlink control signal sent by the base station to the second part of the user equipment includes a downlink control signal sequence s 1 (k); The control signal sequence s 0 (k), s 1 (k) satisfies:

Where N is the number of the plurality of user equipments, W Boost, X is the weight of the kth narrow beam; s 0 * (k) is the conjugate of the s 0 (k), s 1 * (k Is a conjugate of the s 1 (k); H 1 (k) is a channel matrix for transmitting the s 1 (k), and H 0 H (k) is a total of the transmission of the s 0 (k) channel matrix Yoke transpose matrix.
A base station, comprising:

a processor, configured to select one logical port among multiple logical ports corresponding to the physical downlink control channel PDCCH;

And a transmitter, configured to send a downlink control signal to the terminal device on the selected one of the logical ports.
The base station according to claim 14, wherein the processor is further configured to determine that the user equipment is in a single narrow beam coverage.
The base station according to claim 15, wherein the downlink control signal comprises a downlink control signal sequence s0, s1, and the processor is specifically configured to aggregate the downlink control signal sequence s0, s1 into the A single narrow beam corresponds to the transmit on the logical antenna.
The base station according to claim 16, wherein said said base station

The downlink control signal sequence s0, s1 satisfies:

Wherein, W Boost, X is a single narrow beam weights user equipment is located; s 0 s 0 * is the conjugate, s 1 * is the conjugate of s 1; 1 H is a transmission The channel matrix of s 1 , H 0 H is the conjugate transposed matrix of the channel matrix for transmitting s 0 , and γ is the normalization factor.
The base station according to claim 17, wherein said normalization factor
The base station according to any one of claims 14 to 18, wherein the transmitter is further configured to transmit a cell common reference signal CRS.
The base station according to claim 19, wherein said transmitter is further configured to transmit a wide beam CRS signal on a first logical transmit antenna and a plurality of narrow beam synthesis on a second logical transmit antenna A virtual wide beam CRS signal.
The base station according to claim 20, wherein the weight of the CRS signal of the one virtual wide beam synthesized by the plurality of narrow beams is

Wherein, W host0 is a weight of a virtual wide beam fused by M narrow beams, W Boost, M-1 is a weight of the Mth narrow beam, and M is a number of narrow beams.
The base station according to claim 20 or 21, wherein the wide beam has a CRS signal of 65 The CRS signal of a wide beam.
A base station, comprising: a transmitter and a processor;

The transmitter is configured to respectively send a corresponding downlink control signal to each user equipment in the first part of the user equipments of the plurality of user equipments on the first logical port of the plurality of logical ports corresponding to the physical downlink control channel PDCCH;

The processor is configured to determine a time-frequency domain resource of a second logical port of the multiple logical ports of the PDCCH, and the time-frequency domain resource of the second logical port is the same as the time-frequency domain resource of the first logical port ;

The transmitter is further configured to send, on a second logical port of the multiple logical ports of the PDCCH, respective downlink control signals to each user equipment in the second part of the user equipments of the multiple user equipments.
The base station according to claim 23, wherein the processor is further configured to determine that channel conditions of the plurality of user equipments respectively reach a channel threshold, and the base station determines that the plurality of user equipments are respectively in multiple Different single narrow beam coverage.
The base station according to claim 24, wherein the transmitter is configured to transmit a corresponding downlink control signal by using a plurality of different single narrow beams respectively for each user equipment of the multiple user equipments.
The base station according to any one of claims 14 to 25, wherein the downlink control signal transmitted by the transmitter to the first part of the user equipment comprises a downlink control signal sequence s 0 (k), and the transmitter pair is second. The downlink control signal transmitted by the part of the user equipment includes a downlink control signal sequence s 1 (k); the downlink control signal sequence s 0 (k), s 1 (k) satisfies:

Where N is the number of the plurality of user equipments, W Boost, X is the weight of the kth narrow beam; s 0 * (k) is the conjugate of the s 0 (k), s 1 * (k Is a conjugate of the s 1 (k); H 1 (k) is a channel matrix for transmitting the s 1 (k), and H 0 H (k) is a total of the transmission of the s 0 (k) channel matrix Yoke transpose matrix.