Method of SU-MIMO communication differentiating data from reference symbols for power allocation and corresponding apparatus

Abstract

The invention relates to a method (1, 2) of communicating between a transmitter and a receiver of a SU-MIMO system, the system comprising a number of transmit antennas, at least one transmit antenna port and a number of receive antennas, the method comprising:-transmitting (11) to the receiver control information comprising: for a given antenna port (), on a per time-frequency resource element, at least one time-frequency resource element; a power ratio () between reference symbols and data transmitted to user equipment.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of telecommunications. More particularly, the present invention relates, within this field, to digital communication made by a so-called MIMO communication system (MIMO being the acronym for Multiple Input Multiple Output) (i.e. a communication system comprising a transmitter having transmit antennas and a receiver having receive antennas) which allows to allocate power levels on each spatial layer (i.e. on each transmit antenna port) while maximizing the transmission rate.

[0002] In the case of downlink communication, the transmitter can be a base station, such as an eNodeB (Evolved Node B) or a gNodeB in a network based on LTE, LTE-Advanced or newer technologies (5G, etc.), or even a Wi-Fi access point, etc. The receiver can be, as such, a smartphone, a tablet, a connected object, etc. In the case of uplink communication, the transmitter can be a terminal and the receiver can be a base station.

[0003] The present invention is applicable to any system based on beamforming and in particular to radio communication networks according to the 4G, 5G or any newer standard defined by 3GPP, to Wi-Fi communication networks according to various IEEE 802.11 standards, etc. BACKGROUND

[0004] Figure 1 A MIMO communication system is shown, comprising a transmitter having transmit antennas ANT E and a receiver having receive antennas ANT R, with . The system comprises at least one access point (called base station SB in cellular systems) and terminals UE (which are terminals of users).

[0005] In the (3 / 4G) LTE standard prescribed by 3GPP, the number of receive antennas in a smartphone terminal is at least two, while in the case of the NR standard (5G of 3GPP), for certain frequency bands (3.5 GHz n77 / 78), the number of receive antennas in terminals of this type is prescribed to be at least four antennas. As for the base stations, the number of transmit antennas is continuously increasing and, in the case of massive MIMO, it has now reached 64, or even 128 antennas.

[0006] It should be noted that, in the context of the mobile standards of 3GPP, and in the context of the present patent application, an antenna port is associated with a "logical" antenna which can contain one or more radio frequency (RF) chains, each RF chain comprising a digital-to-analog conversion and / or comprising an analog-to-digital conversion. The logical antenna is mapped to RF Chain: The signal sent to the logic antenna is multiplied by this complex vector to generate N inputs to N RF chains.

[0007] Each antenna includes one or more radiating elements.

[0008] While the number of transmit RF chains and receive RF chains is the same in a base station, the situation is different for mobile terminals. These mobile terminals may have fewer transmit RF chains than receive RF chains—typically two transmit RF chains for every four receive RF chains. For base stations, the RF transmit / receive chains are referred to as transceiver units (TXRUs) in the 5G standard.

[0009] Figure 2 Corresponding to specification TS36.211 Figure 6 .3-1 schematically illustrates a portion of the downlink baseband processing of data to be transmitted. In this standard, it is specified that data can be encoded into two streams with different rates. The data, encoded as codewords (Cw), is scrambled using a scrambler (SCR) and then mapped onto a constellation diagram via a mapper (C_MAP). The mapper's output is distributed to the respective spatial layers via a layer mapper (L_map). Each spatial layer (Lay) is then precoded by a precoder (PRE_COD). The precoded data for each spatial layer is mapped by resource elements via a resource mapper (RE_MAP). After output from the resource mapper, the data for each spatial layer is injected into a multicarrier modulator (OFDM) to generate OFDM symbols. These OFDM symbols are fed to antenna ports. Each spatial layer (corresponding to one antenna port) is fed to a single user (or receiver) at a given time. However, a user (or receiver) can benefit from multiple spatial layers simultaneously. This is specified by normative document TS36.211 and corresponds to the following: Figure 5 .3-1 Uplink processing and Figure 2 The processes shown are very similar.

[0010] Conventionally, in telecommunications systems where a transmission channel CH exists between the transmitting section (EM) and the receiving section (RX), the transmission resources are represented by one or more time-frequency grids, one example of which is... Figure 3 As shown, this example corresponds to the 3GPP LTE (4G) standard specification TS36.211. Figure 6 2.2-1.

[0011] In the context of 3GPP's 4G or 5G standards, time-frequency radio resources are resource elements (abbreviated as RE). In this context, resource elements are... Figure 3 The time-frequency grid is indexed The minimum hourly frequency increment is identified by l (i.e., subcarrier and symbol time, which corresponds to the duration of a multicarrier symbol and, in the case of multicarrier OFDM transmission, to the duration of an OFDM symbol). In this grid, frequency is represented by the vertical axis and time by the horizontal axis.

[0012] In the 5G standard, each antenna port, and each of the uplink and downlink directions, has a time-frequency grid. In 5G terminology, frames are divided into multiple subframes. Because the spacing between subcarriers of an OFDM symbol is parameterizable, the number of OFDM symbols included in each subframe varies depending on the spacing between subcarriers, since the duration of a symbol is the reciprocal of the spacing between subcarriers. OFDM symbols are grouped into time slots, each time slot corresponding to the granularity of a known scheduling decision per basic time interval (TTI).

[0013] Regarding radio communication networks defined by 3GPP, mechanisms are specified to allow terminals to connect to base stations. The Physical Downlink Shared Channel (PDSCH) and the Physical Uplink Shared Channel (PUSCH) are the main channels (hereinafter referred to as data channels) used for unicast data transmission and system information transmission, respectively.

[0014] The receiver uses semi-statically defined control information and dynamically transmitted control information in the high (RRC) layer to determine the time-frequency resource elements it must decode. A terminal-dedicated Physical Downlink Control Channel (PDCCH) is used for dynamically transmitting downlink and uplink control information and for scheduling the PDSCH and PUSCH channels.

[0015] The PDCCH channel is organized into one of several possible formats, called the DCI format (DCI stands for Downlink Control Information). The DCI format includes multiple fields, each containing a specific piece of information (e.g., the allocated Physical Resource Block (PRB) (which can be allocated one or two transport blocks), the modulation and coding scheme (MCS) allocated to each transport block, the identifier of the allocated antenna port corresponding to the (semi-static) configuration of the Reference Symbol (DM-RS) at the RRC layer, the spatial layer number (rank), etc.). The information bits of the PDCCH channel (i.e., the bits of the DCI format) are then associated with a CRC code to allow for error detection (CRC stands for Cyclic Redundancy Check). The CRC code is special in that it is scrambled with the terminal's RNTI identifier, which is specific to the PDCCH channel. This allows the terminal to verify that the PDCCH channel it is decoding is indeed intended for the terminal. Specifically, if another terminal (with a different RNTI identifier) ​​attempts to check the validity of the PDCCH channel using a different RNTI identifier, the CRC check returns an error to it.

[0016] As is well known, the capacity of cellular mobile telecommunications networks, especially those defined by 3GPP (LTE / 3G-4G, 5G, etc.), is limited by interference. This interference can take many forms. The following are particularly detrimental to cellular network capacity:

[0017] - SU-MIMO interference (SU-MIMO is an abbreviation for Single User Multiple Input Multiple Output) is related to the use of multiple transmit and receive antennas and corresponds to the interference generated between MIMO data streams allocated to a given receiver device (receiver);

[0018] - MU-MIMO interference (MU-MIMO is an abbreviation for Multi-User-Multiple-Input Multiple-Output) is related to the use of multiple transmit and receive antennas and corresponds to the interference generated between MIMO data streams allocated to different receiving devices (receivers); and

[0019] Inter-cell interference is generated between signals transmitted from different cells to different receiving devices (receivers).

[0020] Various methods that allow for reducing the impact of such interference on network performance are known in the art.

[0021] Therefore, beamforming can be used to mitigate SU-MIMO interference.

[0022] Beamforming is a signal processing technique used in MIMO communication systems, which include arrays of antennas or sensors that allow directional signal transmission or reception. The method involves applying complex coefficients to the data stream transmitted or received by the antennas to impart specific spatial properties (e.g., preferred direction) to the antennas.

[0023] Therefore, the complex coefficients applied to each antenna or antenna port are called precoding coefficients, and all these coefficients together form a precoding matrix implemented by the precoder PRE_COD. Through this precoding, streams intended for a given device can be spatially separated, enabling the receiving device to detect a stream with reduced interference from other streams.

[0024] Therefore, beamforming is achieved by coordinating the elements of the antenna array through phase and amplitude control, in a manner that:

[0025] • Signals exhibit constructive interference in a specific direction

[0026] • Interference cancels out interference in other directions.

[0027] Beamforming can be used on both the transmitting and receiving sides to achieve spatial selectivity.

[0028] By applying appropriate precoding, the transmitter can transmit data on time-frequency radio resources allocated across multiple spatial layers to a single receiver; this is known as SU-MIMO mode.

[0029] The transmitter's choice of appropriate precoding to maximize spectral efficiency (e.g., by evaluating the sum of the bit rates of the MIMO streams) is constrained by transmit power limitations.

[0030] Most existing precoding algorithms are based on optimizing MIMO transmission performance under a single constraint on total transmit power. For example, power allocation known as water-filling allocates power according to channel conditions, maximizing SU-MIMO capacity under a single constraint on the total transmit power of each resource element.

[0031] set up For the data vector to be transmitted to the receiver, The power of each component is normalized to one. The number of spatial layers for transmitting to the receiver over a given set of radio resources. , ,in, The number of transmitting antennas, and The number of receiving antennas, For the precoding matrix, ,and This is a diagonal matrix representing the power transmitted from each antenna port daily. .

[0032] precoding matrix Will Each transmitting antenna is virtualized as Each antenna port. The antenna concept itself can be based on the virtualization of radiating elements. For example, two radiating elements can have the same signal input and therefore share the same virtualized antenna port.

[0033] precoding From size (Right now, Row = Number of transmitting antennas, and A matrix description (column = number of antenna ports), which can be written as:

[0034]

[0035] Then, for a given resource element, the constraint on the total transmit power can be expressed in the following form:

[0036] (1)

[0037] in, For traces, It is the conjugate transpose matrix, also known as the "dagger" matrix. The transpose of the complex conjugate, and Maximum Energy Per Resource Element (EPRE).

[0038] In the 3GPP (5G) standard TS38.214, specifically in Section 4.1 "Downlink Power Allocation" for downlink and Section 6.2.2 "UE DM-RS Transmission Procedure" for uplink, the ratio between the Energy Per Resource Element (EPRE) of the DM-RS reference and the Energy Per Resource Element (EPRE) of the PDSCH and PUSCH data channels is specified. The configurations of the DM-RS are presented in tabular form. A drawback of this approach is that spatial layers with extremely low power allocation will have very noisy channel estimations because the associated DM-RS will also have extremely low power. In this patent application, energy per resource element will also be referred to as power per resource element, although strictly speaking, energy per resource element is the correct term.

[0039] The methods described above are not well-suited for practical MIMO systems, which are characterized by limitations on the transmit power per power amplifier (i.e., each antenna).

[0040] Therefore, the precoding algorithm must satisfy these antenna power constraints while maximizing MIMO communication performance. Therefore, the antenna... The power constraint for transmission must satisfy the following expression:

[0041] (2)

[0042] This can also be written in the following form:

[0043] (3)

[0044] in, This refers to the maximum power of each resource element on the daily online platform, and For in layer Power per resource element under the following conditions.

[0045] The receiver's precoding channel corresponds to: ,in, This corresponds to the channel of the receiver.

[0046] In the receiver, including precoding The precoding channel is estimated based on demodulation reference signals (DM-RS in the case of 5G in LTE or NR systems, or 3GPP) that are orthogonal to each other (in frequency and / or time and / or in code), which are transmitted on the same antenna port as the data intended for the receiver and therefore undergo the same precoding. This estimation of the precoding channel is used at the receiver to demodulate the received signal and decode the data. The reference symbol (DM-RS) carried by the space layer (corresponding to the antenna port) is orthogonal to the reference symbol (DM-RS) carried by another space layer (i.e., another antenna port) and does not interfere with the payload symbol. The reference symbol (DM-RS) is receiver-specific.

[0047] The quality of precoding channel estimation performed at the receiver depends on the received power of the reference signals (DM-RS). However, these reference signals (DM-RS), like the data, are only subject to the maximum total power per resource element during transmission. The single constraint is because each antenna port shares the same time-frequency resource element.

[0048] The drawback of this method is that channel estimation can be very noisy when the data transmitted from the antenna port and the demodulation reference symbol (DM-RS) are allocated very low power. Summary of the Invention

[0049] One aspect of the present invention is a method of using data assigned to the receiver. A method for communication between the transmitter and receiver of a SU-MIMO system, comprising an antenna port dedicated to communication between the transmitter and receiver, and a transmit time-frequency radio resource element. One transmitting antenna, at least One transmit antenna port and One receiving antenna, The method implemented by this transmitter makes:

[0050] - Control information used for communication between the transmitter and the receiver and transmitted by the transmitter includes: for a given transmit antenna port, the power ratio between reference symbols and data transmitted to the receiver per time-frequency radio resource element.

[0051] Another subject of the invention is an embodiment of the invention intended to use data assigned to the receiver. A communication method implemented by the receiver of a SU-MIMO system, comprising an antenna port dedicated to communication between the transmitter and the receiver, and a transmission time-frequency radio resource element, wherein the system further includes a transmitter, the system including... One transmitting antenna, One transmit antenna port and One receiving antenna, This method makes:

[0052] - Control information used for communication between the transmitter and the receiver and received by the receiver includes: for a given antenna port, the power ratio between reference symbols and data transmitted to the receiver per time-frequency radio resource element.

[0053] Another subject of the invention is a communication method intended for use in a SU-MIMO system, the system comprising having One transmitting antenna, at least A transmitter with one transmit antenna port and having A receiver with one receiving antenna. This allows the power allocation to distinguish between the power allocated to the data and the power allocated to the reference symbols intended for use by the receiver, and takes into account the maximum power per transmit antenna.

[0054] Another subject of the present invention is an access point comprising... One transmitting antenna, at least One transmit antenna port and one transmitter. This enables the transmitter to transmit:

[0055] -to have Data from user equipment receiving antennas

[0056] - Reference symbols used to estimate the channel between the access point and the user equipment.

[0057] - Control information, which indicates the control information allocated to the user equipment assigned to it. The transmit time-frequency radio resource element of this antenna port, ,as well as

[0058] - The power ratio between reference symbols and data transmitted to the user equipment per time-frequency radio resource element, for a given antenna port, via a control channel dedicated to the user equipment.

[0059] Another subject of the present invention is an access point comprising... A receiving antenna and a receiver enable the receiver to receive:

[0060] -by having at least Reference symbols transmitted by the terminal at each transmit antenna port.

[0061] - Control information, which includes: for a given antenna port, the power ratio between the reference symbols and data transmitted to the access point on each time-frequency radio resource element, and the control information is transmitted by the terminal.

[0062] Another subject of the invention is a terminal that includes One transmitting antenna, at least One transmit antenna port and a transmitter enable the transmitter to transmit:

[0063] -to have The transmitter uses data from the access point of each receiving antenna, which is allocated to the access point. Each antenna port transmits data using frequency radio resource elements. ,

[0064] - Reference symbols used to estimate the channel between the terminal and the access point.

[0065] - For a given antenna port, the power ratio between the reference symbols transmitted to that access point and the data at each time-frequency radio resource element.

[0066] Another subject of the invention is a terminal that includes A receiving antenna and a receiver enable the receiver to receive:

[0067] -by having at least Reference symbols transmitted from the access point of each transmit antenna port.

[0068] - Control information, which indicates the control information assigned to The transmit time-frequency radio resource element of the antenna port, and the control information is transmitted by the access point. ,

[0069] - Control information, which includes: for a given antenna port, the power ratio between the reference symbols and data transmitted to the terminal on each time-frequency radio resource element, and the control information is transmitted by the access point.

[0070] Another subject of the invention is a method of using data assigned to the receiver. The transmitter has one antenna port and is dedicated to transmitting digital signals between the transmitter and receiver using time-frequency radio resource elements for communication between the transmitter and receiver. One transmitting antenna, at least The receiver has one transmit antenna port. One receiving antenna, This digital signal includes, for a given transmit antenna port, the power ratio between the reference symbol and the data transmitted to the receiver per time-frequency radio resource element.

[0071] Another subject of the invention is a computer program located on an information medium, the program comprising program instructions configured to implement the method according to the invention when the program is loaded and executed in a terminal or access point.

[0072] Another subject of the invention is an information medium comprising program instructions configured to implement the method according to the invention when the program is loaded and executed in a terminal or access point.

[0073] Because this is a problem with SU-MIMO systems, even when different antenna ports are assigned to multiple streams, there is overlap between the stream intended for the receiver and the stream transmitted via time-frequency radio resource elements dedicated to the receiver. The receiver uses at least two antenna ports for communication. Assigned Each antenna port corresponds to the input of the pre-encoder, which... One output is fed into the SU-MIMO system. There are one transmit antenna. Furthermore, the precoding applied to the reference symbols received by the receiver is the same as the precoding applied to the data intended for the same receiver.

[0074] According to this method, regardless of whether the data power at a given antenna port differs from the power of the reference symbol, the receiver uses the power ratio received at the antenna port to correct the precoding channel estimate based on the reference symbol by weighting the received ratio.

[0075] Therefore, the receiver can estimate the precoded transmission channel, including the precoded data, using the received reference symbols under good conditions, without transmitting a precoder or information about the selection of that precoder. Specifically, for a given antenna port, the transmission of the power ratio between the reference symbol and the data at each resource element enables channel estimation at the receiver that is independent of the power allocated to the data transmission channel.

[0076] Because the precoding used by the transmitter can change dynamically, i.e., at the rate at which communication control information is sent, (multiple) power ratios are sent at the same rate (i.e., per transmission time interval (TTI)).

[0077] For example, a SU-MIMO system includes a base station and a terminal. The data is allocated to the receiver and... One transmit antenna port ( The associated transmit radio resources are identified by the base station of the MIMO system using semi-static mechanisms (RRC, etc.) or dynamic mechanisms (via the control channel) in the communication control information transmitted to the terminal. In the case of the 3GPP 5G standard, the communication control channel is, for example, the PDCCH channel.

[0078] In particular, the present invention relates to a given precoding Given daily line power constraints, the power allocation for each line port is optimized by maximizing the Lagrangian dual function using an iterative gradient descent algorithm. Compared to existing techniques, this method significantly simplifies the computations performed in each iteration.

[0079] According to one embodiment of the invention, the control information indicates the configuration of the reference symbols associated with these antenna ports.

[0080] According to one embodiment of the invention, the control information includes a power ratio equal to the number of antenna ports assigned to the receiver.

[0081] According to one embodiment of the invention, this configuration causes the antenna ports to be grouped to form Groups are provided such that these reference symbols are spatially multiplexed by code among these antenna ports of a given group, and wherein the control information includes a single power ratio for each group of antenna ports belonging to the given group and assigned to the receiver.

[0082] According to one embodiment of the invention, the method further includes precoding the data and reference symbols to be transmitted to the receiver using the same precoding matrix, and the composition of the matrix depends on the estimation of the channels between the transmitter and the receiver, which together form a global channel known as a SU-MIMO channel.

[0083] According to one embodiment of the present invention, the precoding matrix is ​​based on an eigenvector matrix, known as the input eigenvector, obtained by performing singular value decomposition on the SU-MIMO channel.

[0084] According to one embodiment of the present invention, the matrix of the channel between the base station and the receiver The singular value decomposition of the singular value is such that ,in, Let the matrix contain all the eigenvectors referred to as these output eigenvectors. Let be a matrix containing all the eigenvectors referred to as these input eigenvectors, and Let be a square matrix containing positive real singular values ​​placed on its diagonal coefficients, and such that... .

[0085] According to one embodiment of the invention, the method further includes determining the power allocated to the data assigned to the antenna port and intended for use by the receiver, in order to maximize the sum of the receiver's rates under the constraint of the maximum power per transmit antenna; this determination is achieved by alternating the following operations: for a given Value, maximizing with respect to the power matrix Lagrange function Then, update the vector based on its gradient. After the value, maximize about Lagrange function ,in, For corresponding A vector of Lagrange multipliers constrained by daily line power.

[0086] According to one embodiment of the invention, determining the power allocated to the data further considers constraints regarding electromagnetic exposure at at least one point in a space defined by the distance from the transmitter. This embodiment makes it possible to simultaneously satisfy the dual constraints of electromagnetic exposure and daily antenna power.

[0087] According to one embodiment of the present invention, the control information is carried by the physical downlink control channel in accordance with mobile telecommunications standards.

[0088] According to one embodiment of the present invention, the data is transmitted via a downlink data channel of a 5G access network.

[0089] According to one embodiment of the present invention, the control information is multiplexed in the uplink data channel according to mobile telecommunications standards. Attached Figure Description

[0090] Other features and advantages of the invention will become more apparent after reading the following description of embodiments given by way of simple illustrative and non-limiting examples, and the description of the accompanying drawings, in which:

[0091] [ Figure 1 ] Figure 1 This is a schematic diagram of a SU-MIMO telecommunications system;

[0092] [ Figure 2 ] Figure 2 This is a very general schematic diagram of the baseband architecture of a transmitter described with reference to existing technology;

[0093] [ Figure 3 ] Figure 3 This is a schematic diagram of a time-frequency grid of resource elements described with reference to existing technologies;

[0094] [ Figure 4 ] Figure 4It is a schematic diagram showing various configurations of the time-frequency grid associated with the antenna port;

[0095] [ Figure 5 ] Figure 5 This is a flowchart of an embodiment of the method according to the present invention;

[0096] [ Figure 6 ] Figure 6 This is a schematic diagram of an embodiment of the access point according to the present invention;

[0097] [ Figure 7 ] Figure 7 This is a schematic diagram showing a terminal according to the present invention. Detailed Implementation

[0098] The background to which this invention applies is as follows: Figure 1 The MIMO telecommunications system shown and described with reference to existing technology. The MIMO system discussed includes at least one access point SB (referred to as a base station in a cellular system) and a terminal UE (which is the user's terminal).

[0099] This transmission system SYS includes a transmitter EM and a receiver that communicates with the transmitter via an integrated channel CH between the transmit antenna ANT_E and the receive antenna ANT_R. Depending on whether the transmission under discussion is uplink or downlink, the transmitter is hosted in either the terminal or the base station, and the receiver is hosted in either the base station or the terminal.

[0100] In the case of downlink transmission, the receiver is also referred to as "user equipment, terminal, or user".

[0101] Transmitter EM includes One transmitting antenna ANT_E ( These transmitting antennas may interfere with each other. Similarly, the receiver RE includes... One receiving antenna ANT_R, ( These receiving antennas may interfere with each other. The overall channel CH can be composed of a size of matrix To describe, among which, —Only a single receiver. The background to which this invention applies is: within a given transmission interval (TTI), only one receiver is scheduled for a given time-frequency radio resource; this system is known as a SU-MIMO system.

[0102] By applying appropriate precoding The transmitter is able to Data is transmitted to the receiver from each antenna port and on the same time-frequency radio resources, while limiting the transmission at the receiver to... Each corresponding antenna port is associated with Interference between received streams , The number of spatial layers assigned to the receiver. ,in The number of transmitting antennas, and This refers to the number of receiving antennas. In other words, the transmission system SYS is a so-called single-user MIMO (SU-MIMO) system.

[0103] precoding matrix Will Each transmitting antenna is virtualized as One antenna port.

[0104] The size of the vector of data intended for the receiver before precoding is That is, the data before precoding is distributed in On each spatial layer (i.e., the antenna port). Precoding From size (Right now, lines and A matrix description of columns. The number of spatial layers that the receiver can receive cannot exceed min( , ).

[0105] The transmitter transmits reference symbols to the receiver using the same antenna port as the data intended for the receiver; that is, these reference symbols are therefore precoded using the same precoding as the data.

[0106] From size The matrix (i.e.) lines and Precoding described by a matrix of columns It can be written as:

[0107]

[0108] Reference symbols transmitted to the receiver are distributed in corresponding time-frequency planes (grids) associated with antenna ports having defined configurations. This configured reference is transmitted to the receiver in a semi-static manner via a protocol associated with the RRC layer, meaning its timescale is much longer than the timescale of scheduling the receiving equipment (downlink) or transmitting equipment (uplink), which is done on a fundamental timescale (so-called TTI). DM-RS reference symbols have various configurations that define CDM groups (CDM stands for Code Division Multiplexing) associated with multiple antenna ports.

[0109] Figure 4This demonstrates the configuration concept for each CDM group under the 5G standard. Each time-frequency grid (whose structure is in...) Figure 3 (As shown in the diagram) corresponds to a space layer or antenna port. Regardless of the configuration of the groups, when a resource element (RE) of a grid carries a reference symbol, no two grids can use the same resource element for data transmission (therefore, for that resource element, the power used for data on each grid is zero), and thus there is no spatial interference between the reference symbol (DM-RS) and the data. However, for the same resource element (RE), reference symbols (DM-RS) may exist in one or more other grids. In this case, to avoid interference between reference symbols (DM-RS) across multiple grids, the reference symbol (DM-RS) carried by a given resource element is encoded using a spreading code that is different between grids, called a spatial code. Since the reference symbols (DM-RS) of a grid can be distributed only in frequency, in time, or both in time and frequency, the spreading code has a frequency dimension, a time dimension, or both a frequency dimension and a time dimension.

[0110] Figure 4 The upper part shows a first example of the configuration of DM-RS reference symbols. This configuration defines CDM groups 0, 1, and 2 for six antenna ports 1000 to 1005, applicable when the DM-RS reference symbols are single symbols (distributed within a single OFDM symbol time), and such that, for a grid, the DM-RS reference symbols are grouped in pairs and occupy two resource elements (REs) along the frequency axis. Between two grids (i.e., two ports) in a given group, the DM-RS reference symbols occupy the same resource elements and are therefore encoded differently using spatial codes, allowing the receiver to distinguish between the different ports. Thus, within a given group and between two ports, the DM-RS reference symbols are orthogonal to each other due to the spatial codes. Between two consecutive groups of grids, for example, between groups CDM 0 and CDM 1, the DM-RS reference symbols are offset by two resource elements REs along the frequency axis. Thus, between different groups of grids, the DM-RS reference symbols are orthogonal to each other in frequency.

[0111] Figure 4The lower half of the diagram illustrates a second example of the configuration of the DM-RS reference symbols. This configuration defines CDM groups 0, 1, and 2 for twelve antenna ports 1000 to 1011, applicable when the DM-RS reference symbols are dual symbols (distributed across two OFDM symbol times), and such that for each grid, the DM-RS reference symbols are grouped into four groups, occupying two resource elements along the frequency axis and two resource elements RE along the time axis. Between two grids within a given group, the DM-RS reference symbols occupy the same resource elements and are therefore encoded differently, allowing the receiver to distinguish between different antenna ports. Thus, within a given group and between two ports, the DM-RS reference symbols are orthogonal to each other due to the spatial code. Between two consecutive groups of grids, for example, between groups CDM 0 and CDM 1, the DM-RS reference symbols are offset by two resource elements RE along the frequency axis. Thus, between different groups of grids, the DM-RS reference symbols are orthogonal to each other in frequency.

[0112] As mentioned above, the receiving device is aware of the configuration of the reference symbols, namely the maximum number of groups and the structure of the groups (the reference symbols are distributed over one or more symbol times, one or more frequencies, the space code used, and the port of each group).

[0113] According to the present invention, power allocation distinguishes between data and reference symbols.

[0114] Power allocation of reference symbols

[0115] Order For antenna port The DM-RS reference symbol has a power of Therefore, it is used to estimate the corresponding precoding channel. ,in For the index of the resource element carrying the symbol, and where This refers to the number of reference symbols for each line port. Based on the DM-RS reference symbol configuration, the power per resource element (EPRE) for each line (expressed as...) This can be shared or not shared among multiple DM-RS reference symbols. Specifically, depending on the configuration of the DM-RS reference symbols, there are several cases to consider:

[0116] -1. The DM-RS reference symbols between each antenna port are only multiplexed via code division (in...) Figure 4In the example in the example, these antenna ports belong to the same CDM group, such as CDM group 0, that is, they are spatially multiplexed within the CDM group, i.e., the reference symbols occupy the same resource elements between different antenna ports, and the reference symbol of a given port is encoded using a spreading code specific to that port and different from that of another port, and therefore the reference symbol of that port is orthogonal to the reference symbol of another port in frequency and / or time) — restatement of relation (3):

[0117] .

[0118] a. When the power is the same across the antenna ports, It is a constant. ,and:

[0119]

[0120] In this case, according to the method according to the invention, for each online port The DM-RS reference symbol allocation is capable of effectively utilizing the available power of the daily line. The power of each resource element is:

[0121] .

[0122] In this case, the power of the DM-RS reference symbol belonging to a given CDM group is therefore the same across the antenna ports, but less than... This may differ between antenna ports. Therefore, the ratio of energy per resource element (EPRE) for the DM-RS reference symbol to the energy per resource element (EPRE) for the data channel is the same as the number of spatial layers. , .

[0123] b. A single ratio between the energy per resource element (EPRE) transmitted in the DM-RS reference symbol and the energy per resource element (EPRE) of the data channel, as required by signaling constraints. In the following circumstances:

[0124] ,therefore .

[0125] In this case, according to the method according to the invention, for each antenna port The power per resource element allocated by the DM-RS reference symbol is:

[0126] .

[0127] -2. The case where DM-RS symbols between antenna ports are not multiplexed on the same resource element, i.e., the vectors transmitted for estimating the precoding channel. With layers Corresponding single non-zero element ——Restatement of relation (3):

[0128] .

[0129] In this case, according to the method according to the invention, for each online port The DM-RS reference symbol allocation is capable of effectively utilizing the available power of the daily line. The power of each resource element is:

[0130] .

[0131] -3. Common scenarios across multiple CDM groups—for example, the former One DM-RS reference symbol belongs to one CDM group, while the rest The symbol belongs to another CDM group.

[0132] ○a. Furthermore, in the case of equally distributed allocation, according to the method according to the invention, for each antenna port The DM-RS reference symbol allocation is capable of effectively utilizing the available power of the daily line. The power of each resource element is:

[0133]

[0134] and

[0135]

[0136] ○b. Or, under signaling constraints requiring each CDM group to transmit a single ratio In the case of this invention, according to the method of each antenna port The DM-RS reference symbol allocation is capable of effectively utilizing the available power of the daily line. The power of each resource element is:

[0137]

[0138] and

[0139]

[0140] in, For the ratio corresponding to the first CDM group, and This corresponds to the ratio of the second CDM group.

[0141] According to situation 3), when there is a quantity of When a port is associated with more than two CDM groups, the allocated power can be determined.

[0142] In the case of distributed allocation, according to the method according to the present invention, for each antenna port The power per resource element allocated by the DM-RS reference symbol is:

[0143]

[0144] and

[0145]

[0146] And for :

[0147]

[0148] Signaling constraints require each CDM group to transmit a single ratio. In the case of this invention, according to the method of each antenna port The power per resource element allocated by the DM-RS reference symbol is:

[0149]

[0150] and

[0151]

[0152] And for :

[0153]

[0154] in, For the ratio corresponding to the first CDM group, For the ratio corresponding to the second CDM group, and

[0155] This represents the ratio corresponding to the j-th CDM group.

[0156] The precoding channel can be represented in the form of the following matrix:

[0157]

[0158] matrix The The column is represented as: .

[0159] Received by the receiver, and by the space layer Related resource elements The transmission of the corresponding signal of the DM-RS reference symbol carried The expression is as follows:

[0160] .

[0161] in, To be with the space layer and resource elements Associated received noise.

[0162] Estimation of precoding channels By Multiply And in This is obtained by performing "averaging / interpolation" on the layer, because this layer... Other resource elements that do not carry DM-RS reference symbols The load is what benefits from the power The data symbols. The result is:

[0163] .

[0164] in, For antenna port (Bearing space layer) The power per resource element of the DM-RS reference symbol, while For antenna port The power of each resource element of the data symbol. Determined by the antenna port. The DM-RS reference symbols and data symbols carried by the resource elements are intended to be used for the same receiver.

[0165] With antenna port Estimation of associated precoding channels Need to know ,because .

[0166] Control information acquired in a semi-static or dynamic manner via a control channel (such as the PDCCH channel in 4G or 5G) and dedicated to the user equipment indicates the time-frequency radio resource elements (REs) assigned to the user equipment for the uplink and downlink channels.

[0167] According to the present invention, the control channel for data transmission between the transmitter and the receiver is indicated on each time-frequency radio resource element (RE) between the DM-RS reference symbol and the data transmitted to the receiver. Power ratio, or . The number of transmitter antenna ports assigned to the transmitter to transmit data to the receiver.

[0168] According to the invention, the control information intended for the receiver therefore includes a space layer assigned for transmission to the receiver. of Individual power ratio:

[0169] or .

[0170] Figure 5 The method 1 according to the invention is illustrated schematically, and is implemented by a transmitter, which is a downlink access point (e.g., a base station in the case of a mobile access network) or an uplink terminal. The transmitter includes... One transmitting antenna and at least One antenna port. The transmitter implements communication method 1 to communicate with the receiver within a given transmission interval (TTI). The receiver includes... One receiving antenna. Therefore, the system, including the base station and user equipment, includes... One receiving antenna. The base station transmits instructions to the user equipment assigned to... Information about the time-frequency radio resource elements transmitted at each transmit antenna port. This transmission is performed using a control channel dedicated to user equipment.

[0171] According to 3GPP mobile telecommunications standards (such as 4G and 5G), this control channel is the PDCCH channel. Furthermore, this information is transmitted within the DCI control information and indicates the time-frequency radio resource element (RE) for each transmit antenna port. The DCI format indicates whether the radio resource is designated for uplink or downlink. For example, a 0-1 format of the DCI specifies that the radio resource is designated for uplink, and a 1-0 format of the DCI specifies that the radio resource is designated for downlink.

[0172] According to method 1, the control information transmitted from the transmitter to the receiver indicates: for a given antenna port The power ratio of the DM-RS reference symbols and data transmitted to the receiver at each time-frequency resource element (RE). In downlink transmission, control information is carried by a dedicated control channel for user equipment, typically the PDCCH channel. In uplink transmission, control information can be multiplexed into a data channel, such as the PUSCH channel in 4G or 5G (PUSCH stands for Physical Uplink Shared Channel).

[0173] The receiver, such as a terminal in the downlink case or an access point in the uplink case (e.g., a base station in the mobile access network case), implements the communication method 2 according to the invention (in... Figure 5 (This is shown very schematically). The receiver receives control information transmitted from the transmitter to the receiver, which indicates: for a given antenna port... The power ratio of the DM-RS reference symbols and data transmitted to the receiver at each time-frequency resource element (RE). .

[0174] When the receiver receives the antenna port dedicated to it When associated with the DM-RS reference symbol, it estimates the precoding channel. Based on the power ratio(s) received in the control information according to the present invention. or The receiver estimates the precoded channel based on the reference symbols. Weighting is performed to obtain the precoding channel. This allows it to subsequently access the same antenna port. The received data is balanced.

[0175] When DM-RS reference symbols belong to different CDM groups, according to the present invention, if for all ports carrying DM-RS reference symbols belonging to the same CDM group, the power ratio of the DM-RS reference symbol carried by a given antenna port to the data power is the same, then the method can transmit only one power ratio for each CDM group to the receiver. .

[0176] Considering only the explanation, The configuration of each CDM group, for the receiver, is based on the channel estimation performed by the DM-RS reference symbols from... The set of CDM groups selected from a CDM group Because the receiver is mapped to multiple antenna ports during transmission, the set... Indicates the port number assigned to the receiver during transmission.

[0177] According to the method of the present invention, the power ratio between the data and the reference symbol for the receiver and each port assigned to the receiver is determined. ( According to one embodiment, the power ratio ( ) is quantized, and each power ratio uses multiple ( (For example, four) bits, and constitute part of the control information transmitted to the receiver, such as being transmitted in the downlink control channel (PDCCH / DCI) or multiplexed in the uplink PUSCH channel.

[0178] SVD of SU-MIMO downlink channel

[0179] from The signals transmitted by each antenna are:

[0180]

[0181] in:

[0182] For a given transmission interval (TTI) to be transmitted to a scheduled receiver, the power of each component of the data vector is normalized to one. The data vector intended for use by the receiver is mapped to... One spatial layer,

[0183] Here is the precoding matrix associated with the receiver, where, The number of spatial layers for launch.

[0184] A diagonal matrix representing the power transmitted from each antenna port—this matrix is ​​associated with the spatial layer mapped to the reference symbols and data transmitted to and intended for use by the receiver.

[0185] Signal received by the receiver It can be written as:

[0186]

[0187] in:

[0188] .

[0189] To have A transmitter with one transmitting antenna to a transmitter with The receiver's transmit channel has one receiving antenna, where... ,

[0190] Let be the noise vector, such that .

[0191] According to a first embodiment of the present invention, it is assumed that the transmitter is connected to a SU-MIMO channel (matrix) ,Right now One transmitting antenna and The channel between each receiving antenna , The knowledge of the number of receiving antennas is complete, and the precoding matrix used is... Corresponding to the channel The matrix of eigenvectors obtained by SVD decomposition The former These columns are called the input feature vectors, and make... Interference between spatial layers can be reduced to zero, meaning these layers are orthogonal to each other.

[0192] In the receiver case, the channel matrix It can be decomposed into singular values ​​(SVD) in the following way:

[0193] ,in, Let be a matrix containing the set of eigenvectors called the output eigenvectors. Let be a matrix containing the set of eigenvectors called the input eigenvectors, and Let be a square matrix containing positive real singular values ​​(eigenvalues) placed on its diagonal coefficients, and such that Received signal Then it can be written as:

[0194]

[0195] Or in fact:

[0196]

[0197] Or in fact, considering the matrix Composition:

[0198]

[0199] According to this first embodiment of the method of the invention, SVD technology is used, and the precoding employed in the SU-MIMO transmission of data and reference symbols intended for the receiver corresponds to that by the channel. SVD decomposition obtained The former List: .

[0200] diagonal power matrix Describes each spatial layer The allocated power, of which, Corresponding to The former Each feature value.

[0201] Signal (in It can be written as:

[0202]

[0203] in, It is a spatially uncorrelated noise vector, i.e. .

[0204] In the following text, eigenvalues Known as layer Associated eigenvalues. Similarly, variance. called layer The variance.

[0205] SVD precoding enables the reduction of interference between the various streams received by the receiver to zero, in order to obtain... An interference-free parallel channel. Therefore, according to this first embodiment, using SVD precoding, the spatial layer... The signal-to-interference-plus-noise ratio (SINR) is given by the following formula:

[0206]

[0207] in, To be with the space layer Corresponding eigenvalues, To be allocated to the space layer The power, and For space layer Noise power.

[0208] Power allocation of data per antenna port

[0209] Determine the power allocated to the data In order to enable daily online power Under constraints, the sum of the rates of each antenna port is maximized. Due to precoding, these antenna ports define mutually orthogonal channels.

[0210]

[0211] Its constraints are: .

[0212] These constraints can be written in the following form:

[0213] ,

[0214] According to the first embodiment (SVD precoding), the signal-to-noise ratio can be expressed as: Form, among which, To be with the space layer Corresponding eigenvalues, To be allocated to the space layer The power, and For layer Noise power.

[0215] Regardless of precoding In what form, in the case of an LMMSE receiver (with a whitening matched filter), the layer The signal-to-noise ratio can be expressed in the following form:

[0216]

[0217] Specifically, the signal received by the receiver It can be written as:

[0218] .

[0219] definition When, the above formula becomes:

[0220]

[0221] in:

[0222]

[0223] To solve constrained optimization problems, regardless of the form of precoding, this invention uses the Lagrangian function defined by the following equation:

[0224]

[0225]

[0226] in, For corresponding A Lagrange multiplier vector with daily line power constraints.

[0227] In the first embodiment (SVD precoding), the Lagrange function can be written in the following form:

[0228]

[0229] Regardless of the form of precoding, dual Lagrange functions Defined as:

[0230]

[0231] Since the utility function (the sum of flow rates) is a convex function, the minimization function is... This is equivalent to optimizing the utility function. The calculation makes... Minimize the vector The utility function can be optimized, thereby optimizing the rate.

[0232] According to the method of the present invention, for a given Value, maximizing with respect to the power matrix Lagrange function Update the vector based on its gradient. The value of , and maximize about Lagrange function Therefore, according to the method of the present invention, the following operations are performed alternately: for a given Value, maximizing with respect to the power matrix Lagrange function And update the vector according to its gradient. After the value, maximize about Lagrange function .

[0233] By repeating these alternating maximizations according to a specific algorithm, the method can converge toward a power allocation matrix that satisfies the daily line power constraint.

[0234] According to the first embodiment, when the pre-encoded type is SVD, one way of implementing the algorithm is provided in simplified form in Appendix A and is described below.

[0235] In the initial steps, the following variables or parameters are initialized: Vectors Initialized to value , The power matrix is ​​initialized to , The iteration index is initialized to zero. Tolerance factor Initialized to a given value, for example And corresponding to Lagrange multipliers learning rate Initialized to a given value, for example .

[0236] For a given The value corresponds to the Lagrangian function with respect to the power matrix. The function that maximizes this is expressed as:

[0237]

[0238] Assigned to space layer The power corresponds to the function The maximum value, that is, when its derivative is zero: And therefore:

[0239] (4)

[0240] Diagonal matrix for power distribution It is given by the following formula:

[0241] (5)

[0242] Since, by definition, the dual Lagrange function is:

[0243]

[0244] So: .

[0245] This method can calculate Initial value:

[0246] After the initialization step, the algorithm in Appendix A is performed as follows.

[0247] -1. The increment of the index in the current iteration. ,

[0248] -2. Given the value obtained in the previous iteration , The current value is determined by Give, and each Regarding vectors The gradient is calculated as follows:

[0249] (6),

[0250] -3. Based on this gradient, for each The update of each Lagrange multiplier is given by the following equation:

[0251]

[0252] in, Lagrange multipliers The learning rate

[0253] -4. According to the equation calculate

[0254] And repeat steps 1 through 4 until... .

[0255] When the difference is less than the threshold The matrix determined in the last iteration Include Power used for data at each of the 1 antenna ports .

[0256] According to the second mode, when the precoding is any other type of precoding (e.g., MMSE type precoding), the calculation is based on the derivation given in equation (4). Numerical differentiation of the Lagrange function is required. A simplified implementation is provided in Appendix B. According to this embodiment, in order to obtain the Lagrange function with respect to... derivative The method according to the present invention follows a numerical derivative-based approach. The descent / ascending gradient method, and assumes that the Lagrangian function is local (around) ) is a convex function.

[0257] Power allocation constrained by electromagnetic field exposure limits

[0258] According to one embodiment of the invention, additional constraints related to electromagnetic field exposure (EMFE) are thus considered. EMFE constraints are a set of points in space. Considering the above, these points can be of any form and do not necessarily correspond to a sphere: each point Received power It shall not exceed the value specified in the text of the regulations. ( Each point It can be identified by its distance from the transmitter.

[0259] Midpoint in space Power received at It is given by the following formula:

[0260]

[0261] in,

[0262] For the transmitted data vector, The power of each component of the data vector is normalized to 1.

[0263] The number of spatial layers from the transmitter to the receiver.

[0264] To describe each spatial layer The diagonal power matrix of the allocated power.

[0265] For the precoding matrix, and

[0266] To indicate the transmitter and point The vector of the channel between them.

[0267] These EMFE constraints are added to the constraints on the daily antenna transmit power, and the performance maximization problem is now given by the following equation:

[0268]

[0269] Its constraints are:

[0270]

[0271] And its constraints are:

[0272]

[0273] To solve constrained optimization problems, this invention uses the Lagrangian function defined by the following equation:

[0274]

[0275] in, Let be a vector of Lagrange multipliers, and let the first part of the vector be the first part of the vector. Each element corresponds to Each daily line power constraint, the vector's subsequent... Each element corresponds to One EMFE constraint.

[0276] According to this embodiment, and with SVD precoding, the Lagrange function becomes:

[0277]

[0278] The algorithm described in the first embodiment can be adapted to take into account all constraints: daily antenna transmission power and various points in space. EMF constraints at the location. Therefore, in the iteration In the middle, the gradient corresponds to the daily antenna transmit power constraint. (for The calculation of ) is given by expression (6), and corresponds to different points in space. gradient of EMFE constraint at point (for The calculation of ) is given by the following expression:

[0279]

[0280] Therefore, according to this embodiment of the present invention, the power determined according to this method Satisfy the daily line power constraint, and ensure that at any point The received power does not exceed the regulatory constraints of EMFE.

[0281] Figure 6 This is a schematic diagram of an embodiment of an access point according to the present invention in the context of a 4G or 5G telecommunications system. The access point PA includes... At least one transmit antenna ANT_E, One antenna port, The access point comprises a receiving antenna RX, a transmitter EM1, a receiver RE1, a memory MEM1 including a buffer memory, and a computer (microprocessor) µP1, the instructions of which allow the implementation of communication method 1 and / or communication method 2 according to the invention. During initialization, the code instructions of program Pg1 are loaded into the buffer memory MEM1, for example, before being executed by the microprocessor µP1. The microprocessor µP1 controls the various components of the access point, including the transmitter EM1 and the receiver RE1.

[0282] Transmitter EM1 includes a transmit chain that typically includes at least one operation (error corrector) for encoding channel input data DATA into COD, a MIMO coding operation, and multi-carrier OFDM modulation to generate data packets TB mapped to a time-frequency resource grid of antenna ports assigned to user equipment (terminals) within a given transmission interval (TTI).

[0283] Transmitter EM1 enables these data packets TB to be transmitted to the user equipment via the PDSCH data channel.

[0284] The EM1 transmitter further enables transmission:

[0285] -DM-RS reference symbol,

[0286] - Control information, which indicates the control information assigned to the user equipment. Each antenna port is identified, along with the transmit time-frequency resource element (RE) allocated to it. This control information is transmitted via the PDCCH control channel dedicated to user equipment using semi-static (RRC) and / or dynamic mechanisms.

[0287] -For a given antenna port The power ratio between DM-RS reference symbols and data transmitted to user equipment on each time-frequency resource element (RE). This ratio is transmitted via the PDCCH control channel dedicated to user equipment.

[0288] Receiver RE1 is enabled to receive DM-RS reference symbols transmitted by the terminal to estimate the uplink channel from the terminal, thereby demodulating the data received by receiver RE1. Receiver RE1 is further enabled to receive:

[0289] -For a given antenna port The power ratio between the received DM-RS reference symbol and the data transmitted to the access point on each time-frequency resource element (RE). This ratio is multiplexed in the uplink data channel PUSCH.

[0290] By executing instructions, the microprocessor µP1 controls the transmitter EM1 to transmit control information via a semi-static (RRC) and / or dynamic mechanism (via a dedicated PDCCH control channel for user equipment). This control information indicates transmit time-frequency resource elements (REs) allocated to at least two antenna ports assigned to the user equipment, and causes the dedicated PDCCH control channel for the user equipment to indicate the transmit time-frequency resource elements (REs) for a given antenna port. The power ratio between the DM-RS reference symbol and the data TB transmitted from the access point to the user equipment on each time-frequency resource element (RE). By executing instructions specific to those received by the base station, the microprocessor µP1 controls the receiver RE1 to receive DM-RS reference symbols from the terminal, and for a given antenna port... At each time-frequency resource element (RE), at least one power ratio between the received reference symbol and the data originating from the terminal and intended for use by the access point. This ratio is multiplexed in the uplink data channel PUSCH.

[0291] By executing instructions, the microprocessor µP1 uses the antenna port assigned to the access point. The received DM-RS reference symbols determine the first estimate of the precoded SU-MIMO channel and utilize the power ratio The first estimate is weighted to obtain a precoded channel estimate of the data TB intended for use at the access point and received by receiver RE1.

[0292] Figure 7 The diagram illustrates a simplified structure of a terminal according to an embodiment of the invention capable of implementing communication methods 1 and 2 according to the invention.

[0293] Terminal UE includes One transmitting antenna ANT_E, A receiving antenna RX, a receiver RE2, a transmitter EM2, a memory MEM2 including a buffer memory, and a computer (microprocessor) µP2, the operation of which is controlled by executing instructions of a program Pg2, which allows the implementation of communication method 1 and / or communication method 2 according to the invention. During initialization, the code instructions of program Pg2 are loaded into the buffer memory MEM2, for example, before being executed by the microprocessor µP2. The microprocessor µP2 controls the various components of the terminal, including the receiver RE2 and the transmitter EM2.

[0294] Receiver RE2 includes the receive chain OFDM / MIMO / COD -1 The receive chain performs the inverse operation of the access point transmit chain in order to receive one or more data packets TB transmitted by the access point via the data transmission channel PDSCH.

[0295] In addition, receiver RE2 enables reception of:

[0296] - DM-RS reference symbol transmitted by the access point,

[0297] - Control information, which indicates the control information assigned to the terminal UE. Each antenna port is identified, and the transmit time-frequency resource element (RE) allocated to the antenna port is used by the access point for transmission. This control information is transmitted by the access point using semi-static (RRC) and / or dynamic mechanisms via a dedicated PDCCH control channel for the terminal UE.

[0298] -For a given antenna port The power ratio between DM-RS reference symbols and data transmitted to the terminal on each time-frequency resource element (RE). The (or these) ratios are carried through the PDCCH control channel dedicated to the terminal UE and transmitted by the access point.

[0299] The EM2 transmitter enables:

[0300] -Emit DM-RS reference symbol.

[0301] Transmitter EM2 includes a transmit chain that typically includes at least one operation (error corrector) for encoding channel input data DATA into COD, a MIMO coding operation, and multi-carrier OFDM modulation to generate data packets TB mapped to a time-frequency resource grid assigned to the antenna ports of the receiver (base station) within a given transmission interval (TTI).

[0302] Transmitter EM2 enables these data packets TB to be transmitted to the base station via the uplink data channel PUSCH.

[0303] The EM2 transmitter further enables transmission:

[0304] -For a given antenna port The power ratio between DM-RS reference symbols and data transmitted to the base station on each time-frequency resource element (RE). This ratio is multiplexed in the data channel PUSCH.

[0305] Therefore, by executing instructions, the microprocessor µP2 controls the receiver RE2 to receive DM-RS reference symbols, control information indicating the transmit time-frequency resource elements REs assigned to at least two antenna ports assigned to the terminal UE, and for a given antenna port... The power ratio between DM-RS reference symbols and data transmitted to the terminal UE on each time-frequency resource element (RE). .

[0306] By executing instructions, the microprocessor µP2 uses the antenna port assigned to the terminal. The received DM-RS reference symbols determine the first estimate of the precoded SU-MIMO channel and utilize the power ratio The first estimate is weighted to obtain a precoded channel estimate of the data TB intended for use at the terminal and received by receiver RE2.

[0307] By executing transmit-specific instructions, the microprocessor µP2 controls the transmitter EM2 to transmit DM-RS reference symbols via channel PUSCH, and for a given antenna port... The power ratio between the DM-RS reference symbol and the data TB transmitted from the terminal to the access point on each time-frequency resource element (RE). This ratio is multiplexed in the uplink data channel PUSCH.

[0308] Controlling the power of the reference symbols used to estimate the precoding channel in the receiver allows for channel estimation quality that is independent of the power allocated to the data at each spatial layer. This power control strategy requires... The power ratio is transmitted from the transmitter to the receiver. The number of spatial layers selected for transmission to the device.

[0309] As a result, the invention is also applicable to one or more computer programs, specifically computer programs on or within a data medium and suitable for implementing the invention. The program may use any programming language and take the form of source code, object code, or intermediate code between source and object code, such as partially compiled code, or any other form of code necessary for implementing the method according to the invention.

[0310] The information medium can be any entity or device capable of storing programs. For example, the medium can include storage devices such as ROM (e.g., CD-ROM or microelectronic circuit ROM), or even magnetic storage devices (e.g., USB key or hard disk).

[0311] On the other hand, the information medium can be a transmissible medium, such as an electrical or optical signal, which can be routed via cable or fiber optic cable, radio, or other means. The program according to the invention can be downloaded, in particular, via the Internet. Alternatively, the information medium can be an integrated circuit incorporating the program, the circuit being designed to execute or to perform the methods discussed.

[0312] In techniques known in the art, to calculate the power ratio between the precoder and the DM-RS and data, the transmitter must know the transmitter-to-receiver channel in advance. This knowledge can be based on the TDD reciprocity principle. The transmitter uses a reference signal transmitted by the receiver to estimate the receiver-to-transmitter channel. Channel reciprocity allows the transmitter-to-receiver channel to be derived from the estimated receiver-to-transmitter channel. In the downlink direction, the reference signal transmitted by the receiver (UE) to obtain the transmit channel through reciprocity is the SRS, while in the uplink direction, the reference signal used is the CSI-RS (transmitted by the access point).

[0313] Another approach can be based on the transmitter-to-receiver channel, which is "quantized" from the receiver (codebook-based MIMO). For example, in the downlink direction, the receiver (UE) can use the CSI-RS transmitted by the transmitter (PA) to estimate the channel.

[0314] Appendix A

[0315] SU-MIMO power allocation algorithm

[0316] -1. Initialization Learning rate of each constraint ,For example ,

[0317] -2. Initialize tolerance threshold ,For example ,

[0318] -3. Lagrange multipliers Initialize to initial value ,For example ,

[0319] -4. Initialize the matrix ,

[0320] -5. Initialize the iteration index, ,

[0321] -6. Calculation

[0322] in ,

[0323] -7. When Execution time:

[0324] -8. ,

[0325] -9. For each Calculate the derivative (gradient). :

[0326] ,

[0327] -10. Based on gradients, for each Calculate the updated values ​​of the Lagrange multipliers:

[0328] ,

[0329] in, Lagrange multipliers The learning rate

[0330] -11. Calculation ,in

[0331] ,

[0332] -12. End the loop.

[0333] -13. Output .

[0334] Appendix B

[0335] For any precoding SU-MIMO power allocation algorithm

[0336] -1. Initialization Learning rate of each constraint , ,For example ,

[0337] -2. Initialize tolerance threshold ,For example ,

[0338] -3. Lagrange multipliers Initialize to initial value ,For example ,

[0339] -4. Initialize the matrix ,

[0340] -5. Initialization ,

[0341] -6. Initialize the iteration index, ,

[0342] -7. When Execution time:

[0343] -8. ,

[0344] -9. For each Calculate the Lagrange function In value numerical derivative at point :

[0345] ,

[0346] -10. For each Calculate the derivative :

[0347] ,

[0348] -11. Calculate the updated value based on the gradient.

[0349] ○Updated values ​​of Lagrange multipliers:

[0350] ,

[0351] ○ and updated power values:

[0352] ,

[0353] -12. End the loop.

[0354] -13. Output .

Claims

1. A method for using data allocated to the receiver. A method (1) for communication between a transmitter (EM) and a receiver (RX) in a SU-MIMO system using a transmit time-frequency radio resource element (RE) with an antenna port dedicated to communication between the transmitter and the receiver, the system comprising One transmitting antenna, at least One transmit antenna port and One receiving antenna, The method is implemented by the transmitter, characterized in that: - Control information used for communication between the transmitter and the receiver and transmitted by the transmitter includes: for a given transmit antenna port ( ), the power ratio between the reference symbol (DM-RS) and data transmitted to the receiver on each time-frequency radio resource element (RE). ).

2. The communication method (1) as described in claim 1, wherein, This control information indicates the configuration of these reference symbols associated with these antenna ports.

3. The communication method (1) as described in claim 1, wherein, The control information includes the same power ratio as the number of antenna ports assigned to the receiver.

4. The communication method (1) as described in claim 2, wherein, This configuration allows these antenna ports to be grouped to form... Groups are provided such that these reference symbols are spatially multiplexed by code among these antenna ports of a given group, and wherein the control information includes a single power ratio for each group of antenna ports belonging to the given group and assigned to the receiver.

5. The communication method (1) as described in any one of claims 1 to 4, further comprising using the same precoding matrix ( The data and reference symbols to be transmitted to the receiver are precoded, and the composition of the matrix depends on the estimation of the channels between the transmitter and the receiver, which together form a global channel known as the SU-MIMO channel.

6. The communication method (1) as described in claim 5, such that the precoding matrix ( The eigenvector matrix, known as the input eigenvector, is obtained by performing singular value decomposition (SVD) on the SU-MIMO channel.

7. The communication method (1) as described in the preceding claim, such that the matrix of the channel between the base station and the receiver... The singular value decomposition of the singular value is such that ,in, Let the matrix contain all the eigenvectors referred to as these output eigenvectors. Let be a matrix containing all the eigenvectors referred to as these input eigenvectors, and Let be a square matrix containing positive real singular values ​​placed on its diagonal coefficients, and such that... .

8. The communication method (1) as claimed in any one of claims 1 to 7, further comprising determining the power allocated to data intended for use by the receiver at the antenna port. This is done by maximizing the sum of the receiver's rates under the constraint of maximum power per transmit antenna; this determination is achieved by alternating the following operations: for a given Value, maximizing with respect to the power matrix Lagrange function Then, update the vector based on its gradient. After the value, maximize about Lagrange function ,in, For corresponding A vector of Lagrange multipliers constrained by daily line power.

9. The communication method (1) as described in claim 8, wherein the power allocated to the data is determined ( Further consideration was given to constraints regarding electromagnetic exposure (EMF) at at least one point in a space defined by the distance from the transmitter.

10. A device designed to use data allocated to the receiver assigned to it. A communication method (2) implemented by the receiver (RX) of a SU-MIMO system, comprising an antenna port and dedicated to communication between the transmitter and the receiver, wherein the system further includes a transmitter (EM), the system comprising One transmitting antenna, One transmit antenna port and One receiving antenna, The method is characterized by: - Control information used for communication between the transmitter and the receiver and received by the receiver includes: For a given antenna port ( ), the power ratio between the reference symbol (DM-RS) and the data transmitted to the receiver on each time-frequency radio resource element (RE).

11. A communication method (1) intended for use in a SU-MIMO system, the system comprising having One transmitting antenna, at least A transmitter (EM) with one transmit antenna port and having A receiver (RX) with one receiving antenna. Its characteristics are, The power allocation distinguishes between the power allocated to the data and the power allocated to the reference symbols intended for use by the receiver, and takes into account the maximum power per transmit antenna.

12. An access point (PA) comprising: At least one transmit antenna (ANT_E), One transmit antenna port and a transmitter (EM1) enable the transmitter (EM1) to transmit: -to have Data (TB) of user equipment (UE) with each receiving antenna. - Reference symbols (DM-RS) used to estimate the channel between the access point and the user equipment (UE). - Control information, which indicates the control information allocated to the user equipment assigned to it. Transmit time-frequency radio resource element (RE) for each antenna port. , Its features are, The transmitter is further capable of transmitting via a dedicated control channel (PDCCH) for the user equipment: for a given antenna port ( ), on each time-frequency radio resource element (RE), the power ratio between these reference symbols (DM-RS) transmitted to the user equipment and the data ( ).

13. A terminal (UE) comprising: At least one transmit antenna (ANT_E), One transmit antenna port and a transmitter (EM2) enable the transmitter (EM2) to transmit: -to have The transmitter uses the data (TB) allocated to the access point (PA) of the receiving antenna assigned to that access point. The data is transmitted using a transmit time-frequency radio resource element (RE) at each antenna port. , - Reference symbols (DM-RS) used to estimate the channel between the terminal and the access point (PA). -For a given antenna port ( ), on each time-frequency radio resource element (RE), the power ratio between these reference symbols (DM-RS) transmitted to the access point (PA) and the data ( ).

14. An access point (PA) comprising: A receiving antenna (RX) and a receiver (RE1) enable the receiver (RE1) to receive: -by having at least Reference symbol (DM-RS) transmitted by a terminal (UE) with each transmit antenna port. Its features are, The receiver (RE1) is further capable of receiving: - Control information, which includes: for a given antenna port (l), the power ratio between these reference symbols (DM-RS) and data transmitted to the access point on each time-frequency radio resource element (RE). (and the control information is transmitted by the terminal.) 15. A telecommunications terminal (UE), the telecommunications terminal comprising: A receiving antenna (RX) and a receiver (RE2) enable the receiver (RE2) to receive: -by having at least Reference symbol (DM-RS) transmitted by the access point (PA) of each transmit antenna port. - Control information, which indicates the control information assigned to this The transmit time-frequency radio resource element (RE) of each antenna port, and the control information is transmitted by the access point. , Its features are, The receiver (RE2) is further capable of receiving: - Control information, which includes: for a given antenna port (l), the power ratio between these reference symbols (DM-RS) and data transmitted to the terminal on each time-frequency radio resource element (RE). (and the control information is transmitted by the access point.) 16. A method for using data allocated to the receiver. The transmitter has one antenna port and is dedicated to transmitting digital signals between the transmitter (EM) and receiver (RX) using the transmit time-frequency radio resource element (RE) for communication between the transmitter and receiver. One transmitting antenna, at least The receiver has one transmit antenna port. One receiving antenna, Its characteristics are, The digital signal includes: for a given transmit antenna port ( ), the power ratio between the reference symbol (DM-RS) and data transmitted to the receiver on each time-frequency radio resource element (RE). ).

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