Access point supporting wireless communication and method of operation thereof

Abstract

A wireless communication employing Channel State Information (CSI) feedback is disclosed. A method of operating a transmitting device (such as an access point) providing wireless communication includes: receiving feedback of channel response information from an external communication device; generating a beamforming matrix based on the channel response information; generating a power allocation matrix based on the average SNR of each of a plurality of streams included in the channel response information; and performing beamforming on the external communication device based on the generated power allocation matrix and the generated beamforming matrix. The channel response information is compressed beamforming feedback of multiple-input multiple-output single-user beamforming. A first power allocated to a first stream among the plurality of streams with a first value of average SNR is greater than a second power allocated to a second stream with a second value of average SNR, the second value being greater than the first value.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 040,644, filed June 18, 2020 with the U.S. Patent and Trademark Office and Korean Patent Application No. 10-2020-0091791, filed July 23, 2020 with the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure generally relates to wireless communication, and more specifically, to access points supporting wireless communication and methods of operation thereof. Background Technology

[0004] Wireless communication provides data communication between various devices via wireless channels. There is a continuous pursuit of improvement to support higher data transmission rates to meet the growing demand for wireless data services.

[0005] A common approach to increasing data transmission rates is called Multiple-Input Multiple-Output (MIMO), which uses multiple transmit antennas at the transmitting device (e.g., an access point in a WLAN system) and multiple receive antennas at the receiving device (e.g., a wireless terminal, user equipment (UE), etc.). Beamforming techniques, used to direct the antenna beams formed by the transmit antennas to a specific receiving device, are being used to improve the efficiency of wireless communication.

[0006] To improve communication quality, the receiving device can measure the condition of the wireless channel, known as "channel state information (CSI)," and feed the CSI back to the transmitting device. The transmitting device can then use the feedback information to perform beamforming adjustment using a technique called precoding, which reduces data errors caused by multipath fading and other factors. Summary of the Invention

[0007] Embodiments of the present invention provide wireless communication with improved reliability and performance.

[0008] According to an exemplary embodiment, an operation method for an access point configured to provide wireless communication includes: receiving feedback of channel response information from an external communication device; generating a beamforming matrix based on the channel response information; generating a power allocation matrix based on the average signal-to-noise ratio (SNR) corresponding to each of a plurality of streams included in the channel response information; and performing beamforming on the external communication device based on the generated power allocation matrix and the generated beamforming matrix. The channel response information is compressed beamforming feedback information for communication based on Multiple-Input Multiple-Output Single-User Beamforming (MIMO SUBF). A first power allocated to a first stream among the plurality of streams with a first average SNR value is higher than a second power allocated to a second stream among the plurality of streams with a second average SNR value, where the second value is greater than the first value.

[0009] According to an exemplary embodiment, an operation method for an access point configured to provide wireless communication includes: receiving feedback of channel response information from an external communication device; generating a beamforming matrix based on the channel response information; selecting a level of modulation and coding scheme; selecting one of a first power allocation matrix and a second power allocation matrix based on the selected level of modulation and coding scheme; and performing beamforming on the external communication device based on the selected one of the first and second power allocation matrices and the beamforming matrix. Each of the first and second power allocation matrices is generated based on information of the average signal-to-noise ratio (SNR) of each of a plurality of streams, wherein this information is included in the channel response information. The first power allocation matrix has a diagonal matrix structure, and the second power allocation matrix has a block-rotated matrix structure. The channel response information is compressed beamforming feedback of Multiple-Input Multiple-Output Single-User Beamforming (MIMO SUBF). A first power allocated to a first stream with a first value of average SNR among the plurality of streams is higher than a second power allocated to a second stream with a second value of average SNR among the plurality of streams, where the second value is greater than the first value.

[0010] According to an exemplary embodiment, an access point configured to provide wireless communication includes: a controller that receives feedback of channel state information from an external communication device, including information about the average signal-to-noise ratio (SNR) of each of a plurality of streams and information about a beam manipulation matrix, and outputs a power allocation matrix and a beam manipulation matrix based on the channel state information; a signal processor that processes data to be transmitted to the external communication device; a power allocation engine that performs power allocation on the signal processed by the signal processor based on the power allocation matrix from the controller; a beamforming engine that performs beamforming based on the output of the power allocation engine and the beam manipulation matrix; and a plurality of antennas that transmit the output of the beamforming engine to the external communication device. The power allocation engine applies the power allocation matrix equally to each of the plurality of subcarriers to perform power allocation, and the transmitting device performs wireless communication with the external communication device using MIMO-based beamforming (MIMO SUBF). Attached Figure Description

[0011] The above and other features of the inventive concept will become apparent when considered in conjunction with the accompanying drawings, and by referring to the following detailed description, in which similar reference numerals denote similar elements or features, wherein:

[0012] Figure 1 This is a block diagram illustrating a wireless communication system according to an embodiment of the concept of the present invention.

[0013] Figure 2 It is shown Figure 1 The flowchart shows the operation of the first communication device.

[0014] Figure 3 It is shown Figure 1 A flowchart of the operation of a wireless communication system.

[0015] Figure 4 It is shown Figure 1 Block diagram of the first communication device and the second communication device.

[0016] Figure 5 It is shown Figure 4 A block diagram of the controller of the first communication device.

[0017] Figure 6 and Figure 7 This shows that a reference has been applied. Figure 4 A graph describing the grouping error performance of the diagonal power matrix.

[0018] Figure 8 This is a block diagram illustrating a controller included in a first communication device according to an embodiment of the present invention.

[0019] Figures 9 to 11 It is used to describe by Figure 8 A graph of the rotational power matrix generated by the rotational power matrix generator of the controller.

[0020] Figure 12 and Figure 13 It shows and applies the reference. Figure 5 The description of the diagonal power matrix configuration corresponds to the grouping error performance and the application of reference. Figure 8 The graph shows the grouping error performance corresponding to the configuration of the described rotating power matrix.

[0021] Figure 14 This is a block diagram illustrating a controller included in a first communication device according to an embodiment of the present invention.

[0022] Figure 15 It shows including Figure 14 A diagram illustrating the operation of the first communication device of the controller.

[0023] Figure 16 and Figure 17 It is used to describe including Figure 14 A graph showing the effect of adaptive power allocation of the first communication device of the controller.

[0024] Figure 18 This is a block diagram illustrating an electronic device conceived according to the present invention. Detailed Implementation

[0025] The embodiments of the present invention will now be described in detail and clearly, so that those skilled in the art can easily implement the present invention.

[0026] In the detailed description or accompanying drawings, the terms "unit," "engine," "module," etc., or functional blocks that perform various operations, may be implemented using circuitry, firmware, hardware circuitry, or various combinations thereof that run software.

[0027] Figure 1 This is a block diagram illustrating a wireless communication system 10 according to an embodiment of the present invention. The wireless communication system 10 may include a first communication device 100 and a second communication device 101, hereinafter referred to simply as "device 100" and "device 101". Each of devices 100 and 101 may be one of various electronic devices configured to support wireless communication, such as an access point (AP), base station, repeater, Wi-Fi router, smartphone, tablet, and laptop computer. (Device 101 may be referred to as an "external communication device" relative to device 100.) For ease of description, it is assumed below that device 100 is an access point (AP) or wireless access point (WAP) connected to a wireless network and configured to provide a wireless network to device 101. It is also assumed that device 101 is a station (e.g., a smartphone) configured to perform wireless communication with device 100. Each of devices 100 and 101 may include a wireless communication chipset conforming to a wireless local area network (WLAN) standard.

[0028] Devices 100 and 101 can perform wireless communication with each other via a wireless channel CH. Devices 100 and 101 can together implement a Multiple-Input Multiple-Output Single-User Beamforming (MIMO SUBF) system, in which a beam formed by multiple antennas at a transmitting device is intended for a single receiving device (single user) with multiple receiving antennas. For example, device 100 may include multiple first antennas ANT11 to ANT1n, and device 101 may include multiple second antennas ANT21 to ANT2m. Devices 100 and 101 can perform wireless communication using the multiple first antennas ANT11 to ANT1n and the multiple second antennas ANT21 to ANT2m. In this case, device 100 can perform beamforming for forming the antenna beam based on channel state information (CSI) (interchangeably, "channel response information") from device 101.

[0029] For example, device 100, configured as an access point (AP), can transmit probe packets (e.g., null data packets (NDP)) via first antennas ANT11 to ANT1n. Probe packets from device 100 can be provided to device 101 via wireless channel CH via second antennas ANT21 to ANT2m. In this case, the received signal associated with the k-th subcarrier (which is included in the probe packets) in the received signal of device 101 can be modeled by Equation 1 below.

[0030] [Equation 1]

[0031]

[0032] In Equation 1, Y k It is the received signal received by device 101; S k It has a size "N" tx ×1” detection signal vector; N tx The number of the first antennas ANT11 to ANT1n of device 100 (i.e., the number of transmitting antennas); E S This represents the total power transmitted by the first antennas ANT11 to ANT1n. H k It is the channel matrix representing the frequency response of channel CH, and the size of the channel matrix is ​​"N". rx ×N tx ”, where N rx This indicates the number of the second antennas ANT21 to ANT2m of device 101 (i.e., the number of receiving antennas of device 101). N k This is received noise. The subscript "k" indicates that the relevant parameter is associated with the k-th subcarrier of the probe packet. For example, Y k S represents the received signal of the k-th subcarrier. k It is the probe signal vector of the k-th subcarrier, and so on.

[0033] Device 101 can estimate the H of channel CH based on the received signal using a channel estimator. k Device 101 can process the estimated H k Perform singular value decomposition (SVD), the result of which can be represented by Equation 2 below.

[0034] [Equation 2]

[0035]

[0036] In equation 2, U k and V k H Each of the elements in ∑ is an identity matrix. k It is a diagonal matrix that includes the singular values ​​of the channel CH (which are arranged diagonally within the matrix). V k H It is V k The conjugate transpose of V k It is a beam manipulation matrix used to perform beamforming.

[0037] Device 101 may feed back Channel State Information (“CSI”) to device 100. For example, devices 100 and 101 may perform wireless communication in accordance with a given wireless communication protocol, and device 101 may feed back CSI to device 100 in accordance with the given wireless communication protocol. The given wireless communication protocol may be based on at least one of various wireless communication schemes, such as Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), and Non-Orthogonal Multiple Access (NOMA)). CDMA may be implemented using radio technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented using radio technologies such as Global System for Mobile Communications (GSM) / General Packet Radio Service (GPRS) / GSM Evolution Enhanced Data Rate (EDGE). OFDMA can be implemented using radio technologies such as IEEE 802.11 (Wi-Fi) (e.g., IEEE 802.11ac, IEEE 802.11ax, or IEEE 802.11n), IEEE 802.16 (WiMAX), IEEE 802-20, or EUTRA (evolved UTRA). UTRA can be part of the Universal Mobile Telecommunications System (UMTS). The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), as part of Evolved UMTS using E-UTRA (E-UMTS), employs OFDMA for the downlink and SC-FDMA for the uplink. LTE-A (Advanced) is an evolution of 3GPP LTE.

[0038] Channel state information conforming to a given wireless communication protocol may include information about the beam manipulation matrix (hereinafter referred to as "IV"). k Device 101 can calculate V by referring to the SVD described in Equation 2 above. k H And it can be based on the calculated V k H To calculate the beam manipulation matrix V k Device 101 can be used as a beam control matrix V k The complex number of the elements is converted into an angle, and information about the angle can be provided to device 100 as at least part of the CSI. Information IV about the beam control matrix. k This can be referred to as "compressed beamforming feedback information" in this paper.

[0039] A CSI conforming to a given wireless communication protocol may include information about the signal-to-noise ratio (SNR) of each stream received at device 100. Hereinafter, the term "stream" can be used to refer to a signal representing a sequence of data received by one of the receiving antennas ANT21 to ANT2m. Depending on the context, a "stream" can be a signal of a specific subcarrier among a plurality of subcarriers transmitted by one or more transmit antennas and received by one or more receive antennas. In other cases, a stream can be a "spatial stream" defined by the energy of a signal arriving from a particular direction, and can be a composite signal derived from at least two signals received by receiving antennas ANT21 to ANT2m. (Analog or digital beamforming performed at receiving device 101 can be used to distinguish between signals arriving from different directions.) In the case of modulation schemes involving concurrent transmission of subcarriers (such as SC-FDMA), each subcarrier may represent different data, and a stream can be a sequence of data represented by a specific subcarrier. Device 101 may calculate information about the average signal-to-noise ratio (SNR) for each stream based on Equation 3 below, and may provide the calculation results to device 100 as channel state information.

[0040] [Equation 3]

[0041]

[0042] Referring to Equation 3 above, AvgSNR db,i Let E{} represent the average signal-to-noise ratio of the i-th stream over a predetermined time period. Let E{} denote the expectation operator. N SS This indicates the number of streams to be transmitted via beamforming of the first communication device 100. σ n 2Surface noise variance. Below, the average signal-to-noise ratio (SNR) of the i-th stream can be expressed in linear units (rather than decibels in Equation 3) and is referred to as the "average SNR". That is, the average SNR of the i-th stream can be expressed by "SNR". i "This indicates that SNR" i It can be represented by Equation 4 below. The average SNR can refer to the individual average signal-to-noise ratio of a specific stream among the multiple streams received at device 101.

[0043] [Equation 4]

[0044]

[0045] Apparatus 100 can perform beamforming based on channel state information provided from apparatus 101. To this end, apparatus 100 can individually allocate power (interchangeably, "power level", "power", or "amplitude") to each of the multiple streams based on the average SNR. In this case, the overall efficiency of wireless communication can be improved, and / or the overall packet error performance can be improved.

[0046] For example, some wireless communication protocols (e.g., IEEE 802.11ac and IEEE 802.11ax) allow or require the same modulation and coding scheme for each stream. Under such conditions, with a high average SNR difference between multiple streams, the probability of errors occurring at streams with relatively low average SNR may increase. This degrades the overall packet error performance. To prevent this degradation, power can be allocated differently for each of the multiple streams. For example, device 100 can do this by using a beam manipulation matrix V included in the CSI. k Perform beamforming. Beam manipulation matrix V k It can be a matrix calculated through singular value decomposition. Since the probability of errors is higher at flows with relatively low average SNR, device 100 can apply a power allocation matrix P. k It can be derived from Equation 5 using knowledge of the other variables in Equation 5 below.

[0047] [Equation 5]

[0048]

[0049] In Equation 5, P k Let H represent the power allocation matrix for the k-th subcarrier; the other variables have been previously defined. The power allocation scheme based on Equation 5 above assumes that device 100 knows the channel response characteristics (i.e., the channel matrix H) of each of the multiple subcarriers. k Under the assumption that ) is used by using the matrix ∑ corresponding to the channel CH k The singular values ​​within the system are subject to water-filling power distribution or reverse water-filling power distribution schemes.

[0050] In an exemplary embodiment, within a specific wireless communication system or protocol, the CSI fed back from device 101 to device 100 may only include information about the beam manipulation matrix V. k Information (“IV”) k ") and the average SNR of each stream. In this case, due to the singular values ​​of each of the multiple subcarriers (e.g., in the matrix ∑ k The frequency response characteristics of each of the multiple subcarriers (e.g., the channel matrix H) were not fed back to the first communication device 100 (in other words, the first communication device 100 failed to identify or was not configured to identify the frequency response characteristics of each of the multiple subcarriers). k Therefore, the power allocation method for each subcarrier based on Equation 5 above may not be applicable to a specific wireless communication system or protocol.

[0051] The apparatus 100, according to an embodiment of the present invention, can provide power allocation for each stream based on the average SNR of each stream. For example, in a particular wireless communication system (e.g., MIMO SUBF), even if the access point fails to identify the channel response or singularity of each subcarrier, total data packet errors can be reduced by performing power allocation based on the average SNR of each stream. An example power allocation method of the apparatus 100 will be described more fully below.

[0052] Figure 2 It is shown Figure 1 A flowchart illustrating the operation of the first communication device 100. (Refer to...) Figure 1 and Figure 2 In operation S110, device 100 may receive channel state information (CSI) from device 101. For example, 100 may be an access point (AP), and 101 may be a user terminal performing wireless communication with device 100. In this case, device 100 may output probe packets. Device 101 may receive probe packets and calculate information about the beam manipulation matrix and the average SNR for each stream based on the received probe packets, and may feed back the calculated information to device 100 as channel state information (CSI). In this regard, device 101 may feed back CSI via channel CH or via a separate feedback channel.

[0053] In operation S120, device 100 may compare the average SNR of each flow included in the CSI. In operation S130, device 100 may perform power allocation for each flow such that the power allocated to the flow with the relatively low average SNR is relatively increased.

[0054] As described above, the device 100 can improve overall data packet error performance by relatively increasing the power allocated to streams with relatively low average SNR.

[0055] Figure 3 It is shown Figure 1 A flowchart illustrating the operation of a wireless communication system. (Refer to...) Figure 1 and Figure 3 In operation S210, device 100 may send probe packets (e.g., empty data packets (NDP)).

[0056] In operation S220, device 101 may receive probe packets NDP and estimate the frequency response H of channel CH based on the received probe packets NDP. k .

[0057] In operation S230, the second communication device 101 can respond to the estimated frequency response H. k Perform singular value decomposition to compute the beam manipulation matrix V. k And average SNR. Calculate the beam manipulation matrix V. k The process for calculating the average SNR can be described as above.

[0058] In operation S240, device 101 can include information about the beam manipulation matrix V k The information "I-Vk" and the channel state information (CSI) of the average SNR are fed back to the device 100.

[0059] In operation S250, device 100 may generate a power allocation matrix based on the average SNR included in the CSI. In an exemplary embodiment, the power allocation matrix may have the same value or be the same matrix for each of the plurality of subcarriers used in the wireless communication between devices 100 and 101.

[0060] In an exemplary embodiment, the power allocation matrix can be in the form of a diagonal structure or a diagonal matrix, in which case the power allocation matrix is ​​specified as "DP", but other implementations are possible. For example, the power allocation matrix can be in the form of a rotated structure or a rotated matrix specified as "RP". (See also...) Figures 4 to 7 The description of the power allocation matrix DP (hereinafter referred to as the "diagonal power matrix") for a diagonal structure will refer to... Figures 8 to 13 The power distribution matrix RP (hereinafter referred to as the "rotating power matrix") describes the rotating structure.

[0061] In operation S260, the first communication device 100 can be based on the power allocation matrix DP or RP and (based on information IV) k The generated beam manipulation matrix V k To perform beamforming. Based on the diagonal power matrix DP and the beam manipulation matrix V... k When beamforming is performed, the power allocated to streams with relatively low average SNR can be relatively increased, thus improving overall data packet error performance.

[0062] Figure 4 It is shown Figure 1 Block diagrams of example circuit components within the first and second communication devices. For the sake of illustration and brevity, only components relevant to the communication methods taught herein are shown.

[0063] Reference Figure 1 and Figure 4 The wireless communication system 10 may include devices 100 and 101, which communicate with each other via a wireless channel (“space channel”) CH. Device 100 may include a signal processor 110, a power distribution engine 120, a beamforming engine 130, a controller 140, and a first transmit antenna TX and a second transmit antenna TX2. Device 101 may include a channel estimation engine 101a, a singular value decomposition engine 101b, a channel state information engine 101c, and a first receive antenna RX1 and a second receive antenna RX2. In other examples, three or more transmit antennas TX and / or receive antennas RX are used; and the methods described herein can be extrapolated to communication systems employing a greater number of antennas.

[0064] Signal processor 110 can perform various signal processing on data to be transmitted from device 100 to device 101. In an exemplary embodiment, signal processor 110 may include various functional blocks for preprocessing data, such as an LDPC tone mapper engine and a cyclic shift delay (CSD) engine provided for each stream.

[0065] Data or signals processed by signal processor 110 can be provided to power distribution engine 120. Power distribution engine 120 can perform power distribution on data or signals processed based on the diagonal power matrix DP generated by controller 140.

[0066] As previously described, device 101 can feed back channel state information (CSI) to device 100. The CSI may include information about the beam manipulation matrix V. k The information and the average SNR of each stream. Specifically, the first receiving antenna RX1 and the second receiving antenna RX2 of the second communication device 101 can receive one or more probe packets output through the first transmitting antenna TX1 and / or the second transmitting antenna TX2. The channel estimation engine 101a can estimate the frequency response H associated with the channel CH based on the received signal. k The singular value decomposition engine 101b can analyze the estimated frequency response characteristics H... k Perform singular value decomposition to calculate the beam manipulation matrix V k The channel state information engine 101c can provide feedback on the beam manipulation matrix V. k Information IV k The average SNR of each stream is used as Channel State Information (CSI).

[0067] The controller 140 can generate the diagonal power matrix DP and the beam control matrix V based on the channel state information (CSI) fed back in this way. k In detail, the diagonal power matrix DP can be represented by Equation 6 below.

[0068] [Equation 6]

[0069]

[0070] Referring to Equation 6, DP represents the diagonal power matrix according to an embodiment of the present invention, p1 to p Nss This represents the diagonal elements of the diagonal power matrix, SNR1 to SNR. Nss Representing the first to Nth order respectively SS The average SNR, τ, and α of the flow are constant values ​​(“constants”). The value of τ can be set in a manner that satisfies the conditions of Equation 7 below.

[0071] [Equation 7]

[0072]

[0073] The variables in Equation 7 have been defined previously.

[0074] It is important to note that the exponent α in Equation 6 can be a constant, used to apply the magnitude of the average SNR of each stream to the power allocation matrix DP. In an exemplary embodiment, the case of α = 1 can be considered as inverse power loading. As is evident in Equation 6, for higher α values, the difference between the average SNRs of each stream is more significantly applied to power allocation; for lower α values, the difference between the average SNRs of each stream is less significantly applied to power allocation. In an exemplary embodiment, the value of α can be predetermined, or it can be a value adjusted during communication in the wireless communication system 10. The value of α can be in the range of 0 to 1.

[0075] As shown in Equation 6, the diagonal power matrix DP can be a diagonal structure or a diagonal matrix. Figure 4 In the example with two transmitting antennas and two receiving antennas, the number of streams (N) used in the wireless communication between the first communication device 100 and the second communication device 101 is... SS There are two. In this case, the diagonal power matrix DP can be in the form of a 2×2 diagonal matrix, and can be represented by the following equation 8.

[0076] [Equation 8]

[0077] in

[0078] In Equation 8, SNR1 represents the average SNR of the first flow, and SNR2 represents the average SNR of the second flow. The remaining variables have been previously defined. This is related to the power allocation matrix P in Equation 5 above. k Unlike Equation 8, the subscript "k" indicating the subcarrier is omitted from the diagonal power matrix DP. This is because the diagonal power matrix DP is applied equally to multiple subcarriers. That is, even if the first communication device 100 fails to identify the characteristics of each subcarrier of channel CH (e.g., H...), the subcarrier's characteristics will be clear. k Alternatively, a diagonal power matrix DP can be generated based on information about the average SNR of each stream.

[0079] The signal processed by the power distribution engine 120 (i.e., the product of the signal processed by the signal processor 110 and the diagonal power matrix DP) can be provided to the beamforming engine 130. The beamforming engine 130 can perform beamforming based on the signal provided from the power distribution engine 120. For example, the beamforming engine 130 can receive a beam manipulation matrix V from the controller 140. k And it can be based on the received beam manipulation matrix V k Beamforming is performed to transmit data through the first transmit antenna TX and the second transmit antenna TX2.

[0080] In an exemplary embodiment, except that the diagonal power matrix DP is applied equally to all subcarriers, the signal processing procedure of the first communication device 100 can be similar to Equation 5 above. That is, according to the embodiment of the present invention, even if the first communication device 100 fails to identify the frequency response H of the channel CH... k The first communication device 100 may also generate a diagonal power matrix DP based on the average SNR of each stream, and may perform power allocation for each of the multiple streams based on the generated diagonal power matrix DP. In this case, since higher power is allocated to the stream with a relatively low average SNR, the overall packet error performance can be improved.

[0081] Figure 5 It is shown Figure 4 A block diagram of the controller of the first communication device. (Refer to...) Figure 4 and Figure 5 The controller 140 may include a beam manipulation matrix (V k Beam control matrix generator 141, variable (γ) calculator 142, constant (α1) calculator 143, and diagonal power matrix (DP) generator 144. Beam control matrix generator 141 can be based on the beam control matrix V included in the channel state information (CSI) fed back from the second communication device 101. k Information IV k To generate the beam manipulation matrix V k The generated beam manipulation matrix Vk It can be provided to beamforming engine 130.

[0082] The variable calculator 142 can generate a variable γ based on the average SNR of each stream included in the channel state information (CSI). In an exemplary embodiment, the variable γ can represent the ratio of the average SNR of two streams. For example, as described above, the number N of streams used in the wireless communication between the first communication device 100 and the second communication device 101. SS When the value is 2, the variable γ can be variable γ1 equal to SNR1 / SNR2 and variable γ2 equal to SNR2 / SNR1 (representing the corresponding ratio in Equation 8). Alternatively, each variable γ represents the deviation of the average SNR of each stream from the reference average SNR.

[0083] The constant calculator 143 can calculate the constant α1 required to generate the diagonal power matrix DP (which is α used in equations 6 and 8). For example, the constant α1 can be a constant used to apply the magnitude of the average SNR of each stream to the power allocation matrix DP. In an exemplary embodiment, the constant α1 can be a value determined according to the coding scheme of the wireless communication system 10 (e.g., modulation and coding scheme (MCS)), the channel environment, etc., or it can be determined during the manufacture of the first communication device 100.

[0084] The diagonal power matrix generator 144 can generate a diagonal power matrix DP based on the variable γ and the constant α1. As mentioned above, the generated diagonal power matrix DP can be "N SS ×N SS The resulting diagonal power matrix DP is in the form of a "" and can be applied equally to each of the multiple subcarriers. The generated diagonal power matrix DP can be provided to the power allocation engine 120.

[0085] Figure 6 and Figure 7 This shows that a reference has been applied. Figure 4 A graph depicting the grouping error performance of the diagonal power matrix. Figure 6 and Figure 7 In the graph, the horizontal axis represents the signal-to-noise ratio (SNR), and the vertical axis represents the packet error performance (PER).

[0086] Figure 6 and Figure 7The graph illustrates performance indicators associated with configurations applying a diagonal power matrix-based power allocation scheme according to embodiments of the present invention and configurations not applying a diagonal power matrix-based power allocation scheme according to embodiments of the present invention. The performance indicators are measured under various modulation and coding conditions (e.g., modulation and coding schemes (MSC)) (e.g., MCS0 to MCS8). For clarity and ease of description, configurations applying a diagonal power matrix-based power allocation scheme according to embodiments of the present invention are indicated by "DPA (Diagonal Power Allocation)," and configurations not applying a diagonal power matrix-based power allocation scheme according to embodiments of the present invention are indicated by "NoPA (No Power Allocation)."

[0087] Figure 6 The graph represents a wireless communication system with two transmitting antennas, two receiving antennas, and two streams. Figure 7 The graph represents a wireless communication system with 4 transmitting antennas, 2 receiving antennas, and 2 streams.

[0088] Reference Figure 6 and Figure 7 Compared to the graph corresponding to NoPA (i.e., the graph associated with a configuration where the power allocation scheme according to the present invention is not applied), the graph corresponding to DPA (i.e., the graph associated with a configuration where the power allocation scheme according to the present invention is applied) shows improved packet error performance. For example, referring to the performance indicator based on the sixth modulation and coding scheme MCS6, at the same SNR, the packet error performance of DPA is higher than that of NoPA. Similarly, each of the remaining modulation and coding schemes (e.g., MCS0 to MCS5, MCS7, and MCS8) can show the similarity difference between the packet error performance of DPA and NoPA (i.e., DPA may have higher packet error performance than NoPA).

[0089] In exemplary embodiments, when the power allocation scheme of the present invention is applied in specific modulation and coding schemes (e.g., MCS0, MCS1, and MCS3), there is a tendency for reduced packet error performance. According to embodiments of the present invention, when the power allocation matrix is ​​implemented in the form of a rotated matrix, the packet error performance according to the specific modulation and coding scheme described above can be improved. The configuration of the power allocation matrix in the form of a rotated matrix, i.e., the configuration of the rotated power matrix RP, will be described below.

[0090] Figure 8 This is a block diagram illustrating a controller included in a first communication device according to an embodiment of the present invention. Figures 9 to 11 It is used to describe Figure 8A graph of the rotational power matrix generated by the rotational power matrix generator of the controller. In an exemplary embodiment, Figure 5 The controller 140 can generate a diagonal power matrix DP with a diagonal structure, while Figure 8 The controller 240 can generate the rotational power matrix RP of the rotating structure.

[0091] Reference Figure 8 The controller 240 may include beam control torque (V k Beam manipulation matrix generator 241, variable (γ) calculator 242, constant (α2) calculator 243, and rotating power matrix (RP) generator 244. Beam manipulation matrix generator 241 and reference... Figure 5 The descriptions are similar, so additional descriptions will be omitted to avoid redundancy.

[0092] The variable calculator 242 can generate variables γ (at least γ1 and γ2, as previously discussed) based on the average SNR of each stream included in the Channel State Information (CSI). In an exemplary embodiment, each variable γ can represent the ratio of the average SNR of each stream. For example, as described above, when the number of streams used in the wireless communication between the first communication device 100 and the second communication device 101 is 2, the variable γ can be SNR1 / SNR2 or SNR2 / SNR1 (as in the equation, or it can be (SNR1 / SNR2)). 1 / 2 Or (SNR2 / SNR1) 1 / 2 Alternatively, each variable γ indicates the deviation of the average SNR of each stream from the reference SNR.

[0093] The constant calculator 243 can calculate the constant α2 required to generate the power allocation matrix RP. The rotating power matrix generator 244 can generate the rotating power matrix RP based on the variable γ and the constant α2. The rotating power matrix RP will be described more fully below. For ease of description, assume the number of flows N. SS The value is 2. The number of flows N SS Given a specific channel characteristic "H", and with the application of a specific channel singular value matrix "V" and power allocation matrix "P", the channel capacity "C" is represented by the following equation 9.

[0094] [Equation 9]

[0095]

[0096] The factors in Equation 9 above have been described above, so further descriptions will be omitted to avoid redundancy. Referring to Equation 9 above, the diagonal matrix form or rotated matrix form can be considered as the power allocation matrix "P". In the case where the power allocation matrix "P" is a diagonal matrix (i.e., the diagonal power matrix DP), PVHH H VH P H The result is in the form of a diagonal matrix. When the power allocation matrix "P" is a rotation matrix (i.e., a rotated power matrix RP), PVHH H V H P H The results may include off-diagonal values. These off-diagonal values ​​may act as inter-stream interference during the reception phase (e.g., in the second communication device 101), and inter-stream interference may degrade packet error performance.

[0097] In an exemplary embodiment, when the receiving phase (e.g., the second communication device 101) is a maximum likelihood (ML) receiver or includes a serial interference cancellation receiver, inter-stream interference can be eliminated at low modulation order or low coding rate (e.g., relatively low level MCS).

[0098] Therefore, the effective throughput can be defined by ignoring the off-diagonal terms in Equation 9. The effective throughput when the power allocation matrix "P" is a rotation matrix (i.e., the rotational power matrix RP) and the effective throughput when the power allocation matrix "P" is a diagonal matrix (i.e., the diagonal power matrix DP) can be represented by Equations 10 and 11, respectively.

[0099] [Equation 10]

[0100]

[0101] [Equation 11]

[0102]

[0103] Equation 10 above shows the first effective throughput Tput when the rotating power matrix RP is applied. RP Equation 11 above shows the second effective throughput Tput when the diagonal power matrix DP is applied. DP The factors in Equations 10 and 11 have been described above, so additional descriptions will be omitted to avoid redundancy.

[0104] In an exemplary embodiment, Figure 9 and Figure 10 The graph shows the first effective throughput Tput based on the ratio of singular values ​​(ratio = σ1 / σ2). RP Second effective throughput Tput DP The curve graph. In Figure 9 In the graph, the horizontal axis represents the angle θ in equation 10 above, and the vertical axis represents the effective throughput Tput. RP .exist Figure 10 In the graph, the horizontal axis represents the angle p1 in equation 11 above, and the vertical axis represents the effective throughput Tput. DP .

[0105] from Figure 9 and Figure 10 As can be understood from the graph, as the ratio of singular values ​​(ratio = σ1 / σ2) increases (i.e., the difference between singular values ​​becomes larger), the power distribution matrix RP in the form of a rotation matrix has a greater effective throughput.

[0106] In an exemplary embodiment, when the rotating power matrix RP is applied, the values ​​of the off-diagonal terms can increase along with the effective throughput. Therefore, appropriate coefficients can be applied to the rotating power matrix RP to improve overall packet error performance.

[0107] Based on the above description, the rotating power matrix RP conceived according to the present invention can be represented by the following Equation 12. In an exemplary embodiment, the rotating power matrix RP of the following Equation 12 shows the relationship between the number of flows N and the total number of flows. SS The schematic form of the rotational power matrix RP corresponding to the case where the value is 2.

[0108] [Equation 12]

[0109] For c 2 +s 2 =1, or

[0110] The factors in Equation 12 above have been described above, so additional descriptions will be omitted to avoid redundancy. The value of θ or "c" of the power allocation matrix RP in Equation 12 above can be determined or calculated based on information about the average SNR for each stream included in the feedback channel state information (CSI). Alternatively, a given set of candidate values ​​for θ or "c" may exist, and a value for θ or "c" can be selected from the given set based on information about the average SNR for each stream, such that the maximum throughput expected for the average SNR of each stream is achieved.

[0111] In an exemplary embodiment, the geometric mean decomposition (GMD) of Equation 13 below can be used to determine the value of θ or “c”.

[0112] [Equation 13]

[0113] GMD(H) = QRP H in

[0114] Referring to Equation 3 above, χ is the inter-flow disturbance term. The remaining factors have been described above, so additional descriptions will be omitted to avoid redundancy. In Equation 13 above, the values ​​of “c” and “s” can be defined as shown in Equation 14 below.

[0115] [Equation 14]

[0116]

[0117] The variables in Equation 14 have been defined previously. Referring to Equations 13 and 14 above, as the ratio of the singular values ​​of the channel (i.e., γ) increases, "c" or cosθ can become smaller. That is, it can be confirmed by Equations 13 and 14 above that as the ratio of the singular values ​​of the channel (i.e., γ) increases, more rotations are needed to obtain the same effective channel gain, thus making the inter-stream interference term χ larger.

[0118] Equation 15 below shows the rotating power matrix RP according to the present invention, which is defined based on Equations 11 to 14 above.

[0119] [Equation 15]

[0120] for and c 2 +s 2 =1, in

[0121] The variables in Equation 15 have been previously defined. Referring to Equation 15, the rotating power matrix RP according to an embodiment of the present invention can be determined by using a "c" value based on the average SNR of each stream. In an exemplary embodiment, the constant α2 can be a compensation coefficient for the rotating power matrix RP. For example, since the power allocation matrix RP, which has a rotating matrix form, is applied equally to all subcarriers, the constant α2 can be a coefficient for compensating RP, unlike a GMD scheme that is applied individually to each subcarrier during the transmission phase (i.e., beamforming).

[0122] In an exemplary embodiment, the constant α2 can be determined in a manner that achieves optimal grouping error performance. For example, Figure 11 The graph illustrates the correlation between the constant α² and Packing Error Performance (PER) for configurations with the rotational power matrix RP applied (i.e., rotational power allocation (RPA)) and configurations without rotational allocation applied (i.e., NoPA). Figure 11 As shown, the grouping error performance can be optimal when the constant α2 is the first value V1, and the first value V1 can be determined as the constant α2 of the rotation power matrix RP.

[0123] As described above, the first communication device 100 according to an embodiment of the present invention can generate a power allocation matrix DP or RP based on information about the average SNR of each stream, and the generated power allocation matrix DP or RP can be applied equally to all subcarriers. In this case, when relatively high power is allocated to streams with relatively low average SNR, the probability of errors occurring at streams with relatively low average SNR can be reduced, thus improving overall packet error performance.

[0124] In the number of flows N SS The above embodiments for example 2 are described, but the inventive concept is not limited thereto. For example, in the number of flows N SS In the case of three or more streams, a power allocation matrix can be generated based on a similar configuration described above. For example, even if the number of streams N... SS For three or more, a diagonal power matrix DP in diagonal matrix form can also be generated based on Equation 6 above.

[0125] Conversely, in the number N of flows SS In the case of three or more flows, the rotation power matrix RP can be implemented by using an identity matrix or by using a block diagonal rotation matrix. For example, in the case of N flows... SS When there are three or more beamforming beams and singular value decomposition (SVD) is applied, the following condition can always be satisfied: SNR1 > SNR2 > ... SNR N ss Here, the rotating power matrix RP can be generated by applying a 2×2 rotation matrix on a two-stream basis. Since the average grouping error is primarily determined based on the performance of the stream with the lowest average SNR, a pair of streams with the highest average SNR and the lowest average SNR can be formed to maximize power allocation to the stream with the lowest average SNR, and the resulting pair can be applied to the rotation matrix. For example, in N... SS When the value is 3, the rotational power matrix RP can be represented by the following equation 16; when N SS When the value is 4, the rotational power matrix RP can be represented by the following equation 17.

[0126] [Equation 16]

[0127]

[0128] [Equation 17]

[0129]

[0130] In Equations 16 and 17 above, the left matrix (i.e., the matrix with all elements being "0" and "1") is a permutation matrix and can be the matrix used to form a pair of streams. In Equation 16, the value of "c" can be determined by the difference between the pairs SNR1 and SNR3. In Equation 17 above, the value of c1 can be determined by the difference between the pairs SNR1 and SNR4, and the value of c2 can be determined by the difference between the pairs SNR2 and SNR3.

[0131] The rotating power matrix RP can be represented by the following Equation 18 for a more general configuration.

[0132] [Equation 18]

[0133] RP = PM PM

[0134]

[0135] Where p i It is N SS ×N SS The i-th column vector of the identity matrix

[0136] For N SS It is an odd number.

[0137] For N SS Even number,

[0138] In Equation 18, RP represents the rotating power matrix, and PM represents N. SS ×N SS An identity matrix of size. In Equation 18, R1 to R... Nss / 2 This represents a 2×2 rotation matrix (i.e., the structure of the rotation power matrix in Equation 15). As described above, R1 to R Nss / 2 The value of (e.g., the "c" value) can be determined based on a pair of average SNRs of the two streams. That is, when the number of streams Nss is odd, the number of Rs in RM can be (N SS -1) / 2; When the number of streams Nss is even, the number of R in RM can be N. SS / 2. Implement R1 to R Nss / 2 The method for the 2×2 rotation matrix is ​​similar to that described above, so additional descriptions will be omitted to avoid redundancy.

[0139] As described above, even if the number of flows Nss is three or more, a pair of flows can be generated based on the average SNR of each flow, and the value of "c" can be determined based on the SNR difference of the generated pairs. The rotational power matrix RP can be generated based on the determined value of "c" using a block diagonal rotation matrix structure.

[0140] Figure 12 and Figure 13 It shows and applies the reference. Figure 5 The description of the diagonal power matrix configuration corresponds to the grouping error performance and the application of reference. Figure 8 The graph depicts the grouping error performance corresponding to the configuration of the described rotating power matrix. Figure 12 and Figure 13 In the graph, the horizontal axis represents the signal-to-noise ratio (SNR), and the vertical axis represents the packet error performance (PER).

[0141] Figure 12 and Figure 13Each of the graphs shows the packet error performance corresponding to the configuration of applying the diagonal power matrix DP and the rotating power matrix RP according to various modulation and coding conditions (e.g., modulation and coding scheme (MSC)). Figure 12 The graph represents a wireless communication system with two transmitting antennas, two receiving antennas, and two streams. Figure 13 The graph represents a wireless communication system with 3 transmitting antennas, 2 receiving antennas, and 2 streams.

[0142] Reference Figure 12 and Figure 13 The graph labeled "DPA (Diagonal Power Distribution)" indicates the configuration of applying the diagonal power matrix DP, while the graph labeled "RPA (Rotating Power Distribution)" indicates the configuration of applying the rotating power matrix RP.

[0143] In some modulation and coding schemes, DPA can have better block error performance than RPA; in other modulation and coding schemes, RPA can have better block error performance than DPA. For example, ... Figure 12 and Figure 13 As shown, in the case of the seventh modulation and coding scheme MSC7, DPA can have better block error performance than RPA at the same SNR. Conversely, in the case of the first modulation and coding scheme MSC1, RPA can have better block error performance than DPA.

[0144] Because the diagonal power matrix DP has a diagonal matrix form, DPA does not cause inter-flow interference. Therefore, in relatively high-level modulation and coding schemes (e.g., MCS6, MCS7, and MCS8), DPA has better packet error performance than RPA. Conversely, because the rotating power matrix RP has a rotated matrix form, PRA causes inter-flow interference. However, because the effective SNR is relatively high in the case of RPA, RPA has better packet error performance than DPA in modulation and coding schemes with relatively low coding rates (e.g., MCS0, MCS1, and MCS3).

[0145] Figure 14 This is a block diagram illustrating a controller included in a first communication device according to an embodiment of the present invention. In an exemplary embodiment, Figure 14 The controller 340 can be applied to reference Figure 1 and Figure 2 The first communication device 100 described may be included therein. (See reference...) Figure 14 The controller 340 may include a beam manipulation matrix (V k Generator 341, variable (γ) calculator 342, constant (α1, α2) calculator 343 and power allocation matrix generator 344.

[0146] Beam control matrix generator 341 can generate beam control matrix V based on channel state information (CSI). k The beam manipulation matrix generator 341 has been described above, so additional descriptions will be omitted to avoid redundancy.

[0147] The variable calculator 342 can generate a variable γ based on the average SNR of each stream included in the channel state information (CSI). In an exemplary embodiment, the variable γ may be information required to generate the diagonal power matrix DP or the rotated power matrix RP. The variable γ may be the deviation of the average SNR of each stream, the difference in the average SNR of the streams, or the ratio of the average SNR of the streams. The configuration of the variable γ according to the form of the power allocation matrix DP or RP has been described above, so additional descriptions will be omitted to avoid redundancy.

[0148] The constant calculator 343 can calculate the constant α1 or α2 required to generate the power allocation matrix DP or RP. In an exemplary embodiment, the constant calculator 343 can output one of the constants α1 or α2 based on information about the modulation and coding scheme MCSx determined by the modulation and coding scheme determiner 345.

[0149] The modulation and coding scheme determiner 345 can select the modulation and coding scheme MCSx to be used for wireless communication based on channel state information (CSI). For example, in standards such as IEEE 802.11 for wireless LANs (WLANs), the modulation and coding scheme can be determined through various combinations of spatial streams, modulation forms, coding rates, etc.

[0150] The power allocation matrix generator 344 can output one of the diagonal power matrix DP and the rotating power matrix RP based on the modulation and coding scheme MCSx selected by the modulation and coding scheme determiner 345.

[0151] For example, as referenced Figure 6 and Figure 7 As described, in some modulation and coding schemes, applying a diagonal power matrix (DP) configuration (i.e., DPA) can lead to degraded packet error performance. Additionally, as referenced... Figure 12 and Figure 13 As described, in some modulation and coding schemes, DPA can have relatively improved packet error performance; in other modulation and coding schemes, the application of a configuration of the rotating power matrix RP (i.e., RPA) can have relatively improved packet error performance. In other words, when one of DPA and RPA is selectively applied according to the modulation and coding scheme, the overall packet error performance of the wireless communication system can be improved.

[0152] Figure 15 It shows including Figure 14 A diagram illustrating the operation of the first communication device of the controller. For ease of description, reference will be made to... Figure 2 The first communication device 100 is described according to Figure 15 The operation of the flowchart. In this case, device 100 may include Figure 14 The controller 340 is configured such that the device 100 can selectively use a diagonal power matrix DP or a rotating power matrix RP depending on the modulation and coding scheme.

[0153] Reference Figure 1 , Figure 14 and Figure 15 In operation S310, device 100 can receive channel status information (CSI) from device 101.

[0154] In operation S320, device 100 may select the level of modulation and coding scheme based on channel state information (CSI). Alternatively, device 100 may select the level of modulation and coding scheme based on various information required in the wireless communication environment or on various other information fed back from the second communication device 101.

[0155] In operation S330, device 100 may select a power allocation matrix based on the modulation and coding scheme of the selected level. For example, device 100 may select a diagonal power matrix DP or a rotating power matrix RP corresponding to the modulation and coding scheme of the selected level.

[0156] In operation S340, the first communication device 100 may perform beamforming based on the selected power allocation matrix.

[0157] As described above, according to embodiments of the present invention, total packet error performance can be improved by selectively or adaptively applying DPA or RPA based on the level of the modulation and coding scheme used in the wireless communication system. In exemplary embodiments, Table 1 below shows exemplary configurations of modulation and coding schemes and power allocation schemes based on the application of the modulation and coding scheme.

[0158] [Table 1]

[0159]

[0160] Referring to Table 1, the number of spatial streams, modulation type, and coding rate can vary depending on the level of the modulation and coding scheme (e.g., MCS index). In an exemplary embodiment, DPA can be applied in the case of modulation and coding schemes with relatively fast coding rates among various levels of modulation and coding schemes; RPA can be applied in the case of modulation and coding schemes with relatively slow coding rates among various levels of modulation and coding schemes. For example, MCS0, MCS1, and MCS3 may have relatively small coding rates (e.g., 1 / 2), and MCS2, MCS4, MCS5, MCS6, and MCS7 may have relatively large coding rates (e.g., 3 / 4, 2 / 3, 5 / 6, etc.). In this scenario, when one of the MCS0, MCS1, and MCS3, which has a relatively low coding rate, is selected as the level of the modulation and coding scheme, the first communication device 100 can perform power allocation or beamforming based on the rotating power matrix RP; when one of the MCS2, MCS4, MCS5, MCS6, and MCS7, which has a relatively high coding rate, is selected as the level of the modulation and coding scheme, the first communication device 100 can perform power allocation or beamforming based on the diagonal power matrix DP. That is, when the coding rate corresponding to the determined level of the modulation and coding scheme is greater than a reference value, the diagonal power matrix DP can be selected; when the coding rate corresponding to the determined level of the modulation and coding scheme is not greater than a reference value, the rotating power matrix RP can be selected.

[0161] Alternatively, even under the same modulation and coding scheme level, DPA or RPA can be selectively applied depending on the communication environment, antenna configuration, etc. For example, when MCS2 is selected as the modulation and coding scheme level, the first communication device 100 can select a diagonal power matrix DP. In this case, when a transmit antenna and a receive antenna are provided to form a 2×2 matrix, a rotated power matrix RP can be selected instead of the diagonal power matrix DP. That is, the first communication device 100 can selectively apply DPA or RPA based on the modulation and coding scheme level, communication environment, antenna configuration, etc.

[0162] In an exemplary embodiment, the configuration for selectively applying the diagonal power matrix DP or the rotating power matrix RP can be determined through various preliminary evaluations, or can be actively (or adaptively) adjusted through the measurement and evaluation of SNR or effective throughput.

[0163] As described above, according to embodiments of the present invention, a first communication device (e.g., an access point) can generate a power allocation matrix based on the average SNR of each of the plurality of streams, and can perform beamforming based on the power allocation matrix thus generated. That is, even if the first communication device (e.g., the access point) fails to identify the channel characteristics associated with each of the plurality of subcarriers, the first communication device (e.g., the access point) can still perform power allocation to each of the plurality of streams based on the average SNR of each of the plurality of streams. In this case, overall packet error performance can be improved by allocating relatively large power to streams with relatively low average SNRs.

[0164] In an exemplary embodiment, according to an embodiment of the present invention, the power allocation matrix generated by the first communication device (e.g., an access point) may have a diagonal matrix structure or a rotated matrix structure. In this case, the first communication device may selectively apply the diagonal power matrix DP or the rotated power matrix RP based on the modulation and coding scheme of the selected level.

[0165] Figure 16 and Figure 17 It is used to describe including Figure 14 A graph showing the effect of adaptive power allocation on the first communication device of the controller. Figure 16 and Figure 17 In the graph, the horizontal axis represents the signal-to-noise ratio (SNR), and the vertical axis represents the packet error performance (PER).

[0166] Figure 16 and Figure 17 The graphs show performance indicators under various modulation and coding conditions (e.g., modulation and coding schemes (MSC)) (e.g., MCS0 to MCS8), i.e., compared with those applied using a reference. Figure 14 and Figure 15 The power allocation scheme described (i.e., adaptively applying the diagonal power matrix DP and the rotating power matrix RP according to the MCS level) (hereinafter, for ease of description, the adaptive application is referred to as "Adaptive Power Allocation (APA)") and the configuration without adaptive power allocation are associated with performance indicators. For the sake of brevity and ease of description, the configuration with the adaptive power allocation scheme applied according to embodiments of the present invention is indicated by "APA (Adaptive Power Allocation)," and the configuration without the adaptive power allocation scheme applied according to embodiments of the present invention is indicated by "NoPA (No Power Allocation)."

[0167] like Figure 16 and Figure 17As shown in the graph, in the configuration applying the adaptive power allocation scheme according to an embodiment of the present invention (i.e., in APA), the packet error performance is improved at all MCS levels compared to the configuration without the adaptive power allocation scheme (i.e., NoPA). This is because power allocation is performed at MCS levels with relatively high coding rates without inter-stream interference using the diagonal power matrix DP, and power allocation is performed at MCS levels with relatively low coding rates using the rotated power matrix RP, resulting in improved effective SNR.

[0168] As described above, according to embodiments of the present invention, total packet error performance can be improved by selectively applying a power allocation matrix based on the MCS level.

[0169] Figure 18 This is a block diagram illustrating an electronic device 1000 according to an invention. The electronic device 1000 may include a main processor 1100, a touch panel 1200, a touch driver integrated circuit (TDI) 1202, a display panel 1300, a display driver integrated circuit (DDI) 1302, a system memory 1400, a storage device 1500, an audio processor 1600, a communication block 1700, an image processor 1800, and a power management integrated circuit 1900. In an exemplary embodiment, the electronic device 1000 may be one of various electronic devices such as portable communication terminals, personal digital assistants (PDAs), portable media players (PMPs), digital cameras, smartphones, tablet computers, laptop computers, and wearable devices, or it may be one of various communication devices (such as wireless routers and wireless communication base stations) supporting wireless communication relay functions. In an exemplary embodiment, in addition to Figure 18 In addition to the components shown, the electronic device 1000 may include any other components, or may exclude them. Figure 18 Some of the components shown.

[0170] The main processor 1100 controls the overall operation of the electronic device 1000. The main processor 1100 controls / manages the operation of the components of the electronic device 1000. In order to operate the electronic device 1000, the main processor 1100 can handle various operations.

[0171] Touch panel 1200 can be configured to sense touch input from a user under the control of touch driver integrated circuit 1202. Display panel 1300 can be configured to display image information under the control of display driver integrated circuit 1302.

[0172] System memory 1400 may store data for the operation of electronic device 1000. For example, system memory 1400 may include volatile memory such as static random access memory (SRAM), dynamic RAM (DRAM), or synchronous DRAM (SDRAM), and / or non-volatile memory such as phase change RAM (PRAM), magnetoresistive RAM (MRAM), resistive RAM (ReRAM), or ferroelectric RAM (FRAM).

[0173] Regardless of whether it is powered on, storage device 1500 can store data. For example, storage device 1500 may include at least one of various non-volatile memories such as flash memory, PRAM, MRAM, ReRAM, and FRAM. For example, storage device 1500 may include embedded memory and / or removable memory of electronic device 1000.

[0174] The audio processor 1600 can process audio signals using the audio signal processor 1610. The audio processor 1600 can receive audio input via the microphone 1620 or provide audio output via the speaker 1630.

[0175] Communication block 1700 can exchange signals with external devices / systems via antenna 1710. The transceiver 1720 and modulator / demodulator (MODEM) 1730 of communication block 1700 can process signals exchanged with external devices / systems based on at least one of the following wireless communication protocols: Long Term Evolution (LTE), Global Microwave Access Interoperability (WiMAX), Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), Bluetooth, Near Field Communication (NFC), Wi-Fi, and Radio Frequency Identification (RFID). In an exemplary embodiment, antenna 1710 of communication block 1700 may include multiple antennas and can perform MIMO-based communication with external communication devices. In an exemplary embodiment, when electronic device 1000 operates as an access point (AP), communication block 1700 can be based on reference... Figures 1 to 15 The described method or structure performs power allocation for each stream.

[0176] Image processor 1800 can receive light through lens 1810. Image device 1820 and image signal processor (ISP) 1830 included in image processor 1800 can generate image information about external objects based on the received light.

[0177] The power management integrated circuit 1900 can be configured to receive power from a battery or any other power source and supply power to the main processor 1100 or various other components.

[0178] According to embodiments of the present invention, the communication device can generate a power allocation matrix based on the average SNR of each stream. Therefore, in a communication environment where the channel characteristics of each subcarrier are unknown, overall packet error performance can be improved by allocating relatively large power to streams with relatively low average SNR. Thus, a communication device and its operating method with improved reliability and performance are provided.

[0179] Although the inventive concept has been described with reference to exemplary embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications may be made to the inventive concept without departing from the spirit and scope of the inventive concept set forth in the claims.

Claims

1. An operating method of an access point configured to provide wireless communication, the method comprising: Receive feedback of channel response information from external communication devices; A beam manipulation matrix is ​​generated based on the channel response information; A power allocation matrix is ​​generated based on the average signal-to-noise ratio for each of the multiple streams included in the channel response information. as well as Beamforming is performed on the external communication device based on the generated power allocation matrix and the generated beam manipulation matrix. The channel response information includes compressed beamforming feedback information based on multi-input multi-output single-user beamforming communication, and Wherein, the first power of the first stream, which has an average signal-to-noise ratio of a first value, is allocated to the plurality of streams, and the second power of the second stream, which has an average signal-to-noise ratio of a second value, is higher than the first value.

2. The method according to claim 1, wherein, The power allocation matrix is ​​applied equally to each of the multiple subcarriers.

3. The method according to claim 1, wherein, The power allocation matrix is ​​generated based on a constant value and the ratio of the average signal-to-noise ratios of two of the plurality of streams.

4. The method according to claim 1, wherein, The power allocation matrix is ​​either a first power allocation matrix with a diagonal matrix structure or a second power allocation matrix with a rotated matrix structure.

5. The method according to claim 4, further comprising: Determine the level of the modulation and coding scheme used in wireless communication with the external communication device.

6. The method according to claim 5, wherein, Based on the modulation and coding scheme of the determined level, one of the first power allocation matrix and the second power allocation matrix is ​​selected as the power allocation matrix.

7. The method according to claim 6, wherein, When the coding rate corresponding to the modulation and coding scheme of the determined level is greater than the reference value, the first power allocation matrix is ​​selected as the power allocation matrix, and when the coding rate corresponding to the modulation and coding scheme of the determined level is not greater than the reference value, the second power allocation matrix is ​​selected as the power allocation matrix.

8. The method according to claim 4, wherein, When the number of the plurality of flows is Nss, where Nss is a positive integer, the power allocation matrix is ​​a diagonal matrix of size Nss×Nss and is constrained based on the following equation: Where DP is the power allocation matrix, p1 to p... Nss Represents the diagonal elements of the diagonal matrix, SNR1 to SNR Nss τ and α are the average signal-to-noise ratios of the multiple streams, respectively, and τ and α are constants.

9. The method according to claim 8, wherein, α is a value between 0 and 1, and Wherein, τ is restricted to satisfying the following equation:

10. The method according to claim 8, wherein, The power allocation matrix is ​​a block rotation matrix of size Nss×Nss and is defined as follows: Where p i It is the i-th column vector of the Nss×Nss identity matrix. For Nss to be odd For Nss to be even Where RP is the power allocation matrix, and PM is N SS ×N SS A permutation matrix of size R1 to R2, where R1 is a permutation matrix of size R2. Nss / 2 The rotation matrix.

11. The method according to claim 10, wherein, R1 to R Nss / 2 Based on the following constraint: Where Rx represents R1 to R Nss / 2 In each of these, α is a constant value that is equal to or greater than 0 and equal to or less than 1, and SNR a and SNR b It is among the multiple flows that are R1 to R Nss / 2 The signal-to-noise ratio of each corresponding pair in the diagram.

12. The method according to claim 1, wherein, The wireless communication is a wireless local area network communication based on IEEE 802.

11.

13. The method according to claim 1, wherein, The beam manipulation matrix is ​​generated based on singular value decomposition.

14. An operating method of an access point configured to provide wireless communication, the method comprising: Receive feedback of channel response information from external communication devices; A beam manipulation matrix is ​​generated based on the channel response information; Select the level of the modulation and coding scheme; Choose one of the first power allocation matrix and the second power allocation matrix based on the modulation and coding scheme of the selected level; as well as Beamforming is performed on the external communication device based on a selected one of the first power allocation matrix and the second power allocation matrix, and the beam manipulation matrix. Each of the first power allocation matrix and the second power allocation matrix is ​​generated based on information about the average signal-to-noise ratio of the corresponding multiple streams, and this information is included in the channel response information. The first power allocation matrix has a diagonal matrix structure, and the second power allocation matrix has a block rotation matrix structure. The channel response information is compressed beamforming feedback for multiple-input multiple-output single-user beamforming, and... Wherein, the first power of the first stream, which has an average signal-to-noise ratio of a first value, is allocated to the plurality of streams, and the second power of the second stream, which has an average signal-to-noise ratio of a second value, is higher than the first value.

15. The method according to claim 14, wherein, When the coding rate corresponding to the modulation and coding scheme of the selected level is greater than the reference value, the first power allocation matrix is ​​selected; otherwise, the second power allocation matrix is ​​selected.

16. The method of claim 14, wherein, The modulation and coding scheme levels include levels 0 to 7 as defined by the IEEE 802.11 standard. Specifically, when the selected modulation and coding scheme level is level two, level four, level five, level six, or level seven, the first power allocation matrix is ​​selected, and Specifically, when the selected level of the modulation and coding scheme is level 0, level 1, or level 3, the second power allocation matrix is ​​selected.

17. The method according to claim 16, wherein, When the selected modulation and coding scheme level is the second level, the number of transmit antennas in the access point is 2, and the number of receive antennas in the external communication device is 2, the second power allocation matrix is ​​selected instead of the first power allocation matrix.

18. An access point configured to provide wireless communication, comprising: The controller is configured to receive feedback of channel state information from an external communication device, including information about the average signal-to-noise ratio of each of the multiple streams and information about the beam control matrix, and to output a power allocation matrix and the beam control matrix based on the channel state information. A signal processor is configured to process data to be sent to the external communication device; A power distribution engine is configured to perform power distribution on signals processed by the signal processor based on the power distribution matrix from the controller; A beamforming engine is configured to perform beamforming based on the output of the power distribution engine and the beam manipulation matrix; as well as Multiple antennas are configured to transmit the output of the beamforming engine to the external communication device. The power allocation engine applies the power allocation matrix equally to each of the plurality of subcarriers to perform the power allocation, and The transmitting device uses multiple-input multiple-output (MIMO) beamforming to perform the wireless communication with the external communication device.

19. The access point according to claim 18, wherein, The transmitting device is an access point, and the power allocation matrix includes a first power allocation matrix with a diagonal matrix structure or a second power allocation matrix with a rotation matrix structure.

20. The access point according to claim 19, wherein, The controller includes: A modulation and coding scheme determiner is configured to determine the level of the modulation and coding scheme to be used in the wireless communication; and A power allocation matrix generator is configured to generate one of the first power allocation matrix and the second power allocation matrix as the power allocation matrix based on the level of the modulation and coding scheme determined by the modulation and coding scheme determiner.

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