Communication device and method for multiple-input multiple-output data detection

Abstract

A communication device includes an inter-layer interference cancellation circuit to cancel a first inter-layer interference of a first observation signal to generate a first interference cancellation signal; a first determination circuit coupled to the interlayer interference cancellation circuit for determining a first center of a first search area according to the first interference cancellation signal; a second decision circuit, coupled to the first decision circuit, for determining a first size of the first search area according to a first Gaussian interruption probability and a first signal-to-noise ratio; and a third decision circuit, coupled to the second decision circuit, for determining a first number of at least one first candidate symbol of the first interference cancellation signal according to the first size of the first search area.

Description

Technical Field

[0001] This invention relates to a communication apparatus and method for a wireless communication system, and more particularly to a communication apparatus and method for setting up a simple search region layer by layer in data detection of a multiple-input multiple-output orthogonal frequency division multiplexing system. Background Technology

[0002] In multiple-input multiple-output (MIMO) systems, multiple antennas at the transmitting end can transmit independent signals, while each antenna at the receiving end can simultaneously receive signals from all antennas at the transmitting end. This increases multipath diversity gain, antenna gain, and potential beamforming gain between transmission and reception, significantly improving system capacity and throughput. Orthogonal frequency-division multiplexing (OFDM) is also widely used to simplify channel equalization at the receiving end. Combining the advantages of both at the system level allows for flexible multi-user transmission through wireless resource scheduling, making MIMO-OFDM the mainstream design for the physical layer in modern communication systems. However, with the increasing number of users and bandwidth requirements, the total number of tones is also increasing. With the increasing modulation order of modulation / demodulation methods, the number of candidate symbols to be detected per-tone / per-subcarrier also increases. The increasing number of antennas and spatial streams further increases the number of layers to be processed, and also increases inter-layer interference (ILI). This multi-dimensional increase forces communication receivers to process inter-layer interference per layer and per-tone, while simultaneously detecting all possible candidate symbols in each layer, resulting in extremely high detection complexity. How to define a concise search area for each layer, reducing the number of candidate symbols within it, and thus lowering data detection complexity, has become a pressing problem. Summary of the Invention

[0003] One of the objectives of this invention is to provide a communication device and method for data detection in a multiple-input multiple-output orthogonal frequency division multiplexing system, by setting up a concise search region layer by layer to reduce the number of candidate symbols to be tested within it, thereby solving and significantly reducing the aforementioned high complexity problem.

[0004] This invention discloses a communication device comprising: an inter-layer interference cancellation circuit for removing first inter-layer interference (ILI) of a first observed signal to generate a first interference cancellation signal; a first determination circuit coupled to the inter-layer interference cancellation circuit for determining a first center of a first search region (SR) based on the first interference cancellation signal; a second determination circuit coupled to the first determination circuit for determining a first size of the first search region based on a first Gaussian outage probability and a first signal-to-noise ratio (SNR); and a third determination circuit coupled to the second determination circuit for determining a first number of at least one first candidate symbol of the first interference cancellation signal based on the first size of the first search region.

[0005] This invention also discloses a data detection method for a multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) system, comprising: removing inter-layer interference (ILI) of the observed signal to generate an interference cancellation signal; determining the center of a search region (SR) based on the interference cancellation signal; determining the size of the search region based on the Gaussian outage probability and the signal-to-noise ratio (SNR); and determining the number of at least one candidate symbol of the interference cancellation signal based on the size of the search region.

[0006] This invention provides a communication apparatus and method. The communication apparatus determines a search area and performs data detection only on candidate symbols within the search area. Therefore, the communication apparatus does not detect all candidate symbols, thereby reducing the complexity of multiple-input multiple-output data detection and saving the resources of the communication apparatus. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of a wireless communication system according to an embodiment of the present invention.

[0008] Figure 2 This is a schematic diagram of a communication device according to an embodiment of the present invention.

[0009] Figure 3 This is a schematic diagram of the interference cancellation signal according to an embodiment of the present invention.

[0010] Figure 4 This is a flowchart illustrating the process of an embodiment of the present invention. Detailed Implementation

[0011] Figure 1 This is a schematic diagram of a communication system 10 according to an embodiment of the present invention. The communication system 10 can be any communication system using orthogonal frequency-division multiplexing (OFDM) technology (or discrete multi-tone modulation (DMT) technology), and may include a transmitting end 12 and a receiving end 14. The communication system 10 may include wired communication systems such as asymmetric digital subscriber line (ADSL) systems, but is not limited thereto. The communication system 10 may include wireless local area network (WLAN), digital video broadcasting (DVB) systems, Long Term Evolution (LTE) systems, LTE-advanced (LTE-A) systems, or 5th generation wireless communication (5G) systems, but is not limited thereto. Furthermore, the transmitter 12 and receiver 14 can be installed in devices such as user equipment (UE), mobile phones, laptops, personal computers, tablets, e-readers, portable computer systems, access points (APs), and smartwatches, but are not limited to these.

[0012] Figure 2 This is a schematic diagram of a communication device 20 according to an embodiment of the present invention. For example, the communication device 20 can be used in... Figure 1In the receiver 14, data detection is performed for a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system. The communication device 20 includes an inter-layer interference (ILI) cancellation circuit 210 (hereinafter referred to as "interference cancellation circuit 210"), a first decision circuit 220, a second decision circuit 230, and a third decision circuit 240. Specifically, the interference cancellation circuit 210 is used to cancel the first inter-layer interference of the first observed signal to generate a first interference cancellation signal. The first decision circuit 220 is coupled to the interference cancellation circuit 210 and is used to determine the first center of the first search region (SR) (or the first concise search region) based on the first interference cancellation signal. The second decision circuit 230 is coupled to the first decision circuit 220 and is used to determine the first size of the first search region based on the first Gaussian outage probability and the first signal-to-noise ratio (SNR). The third decision circuit 240 is coupled to the second decision circuit 230 and is used to determine the first number of at least one first candidate symbol (e.g., constellation) of the first interference cancellation signal based on the first size of the first search region.

[0013] In an embodiment, the communication device 20 further includes a channel estimation circuit and / or a synchronization circuit (not shown). Figure 2 (In the middle). The channel estimation circuit and / or synchronization circuit are used to process the data received from the receiver 12 to generate an observation signal. The channel estimation circuit or synchronization circuit transmits the observation signal to the interference cancellation circuit 210.

[0014] In this embodiment, the communication device 20 further includes a fourth decision circuit and a data detection circuit (not shown). Figure 2 (In the middle). A fourth decision circuit is coupled to the third decision circuit and is used to determine at least one first candidate symbol in the first search area based on the first center of the first search area and the first number of at least one first candidate symbol. A data detection circuit is coupled to the fourth decision circuit and is used to detect at least one first candidate symbol to generate a first detection signal corresponding to the first observation signal.

[0015] In one embodiment, the first observation signal includes a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) signal. In another embodiment, the first observation signal includes at least one first complex value. In yet another embodiment, the at least one first complex value corresponds to at least one antenna of the communication device 20.

[0016] In an embodiment, the first interlayer interference includes at least one second complex value. In an embodiment, the at least one second complex value corresponds to at least one antenna of the communication device 20. In an embodiment, each of the at least one second complex value includes both real and imaginary numbers. In an embodiment, the probabilities of the real and imaginary numbers in each second complex value follow a Gaussian distribution.

[0017] In an embodiment, the interference cancellation circuit 210's step of eliminating the first inter-layer interference of the first observation signal includes: performing a Sorted QR decomposition (SQRD) on the first observation signal based on the first observation vector and the first channel matrix to eliminate the first inter-layer interference of the first observation signal. In an embodiment, the first observation signal is located at the last element (entry) of the first observation vector, and the first channel vector corresponding to the first observation signal is located at the last column vector of the first channel matrix. In an embodiment, the SQRD decomposition is a sorted QR decomposition.

[0018] In an embodiment, the step of the first decision circuit 220 determining the first center of the first search region based on the first interference cancellation signal includes: performing a hard decision (HD) for the first interference cancellation signal through zero forcing (ZF) and slicing to determine the first center of the first search region. For example, the first center of the first search region is determined to be the candidate symbol closest to the first interference cancellation signal.

[0019] In one embodiment, the step of the second decision circuit 230 determining the first size of the first search region based on the first Gaussian interrupt probability and the first signal-to-noise ratio includes: determining the first Gaussian interrupt probability; determining a parameter corresponding to the Gaussian tail-end probability based on the first Gaussian interrupt probability; and determining the first size of the first search region based on the parameter and the first signal-to-noise ratio. In one embodiment, the first Gaussian interrupt probability is dynamically adjusted according to the current situation. In one embodiment, the first Gaussian tail-end probability is a Gaussian Q function. In one embodiment, the first size of the first search region includes the side length of the first search region. In one embodiment, the first size of the first search region includes half the side length of the first search region.

[0020] In an embodiment, the first number of at least one first candidate symbol is not greater than a threshold. In an embodiment, the threshold is the order of the modulation / demodulation mode of the communication device 20. For example, the modulation / demodulation mode may be Quadrature Amplitude Modulation (QAM), but is not limited to this. In an embodiment, the communication device operates in an Nr×Nt multiple-input multiple-output quadrature frequency division multiplexing system, where Nr is the communication device (e.g., Figure 1 The number of antennas at the receiver 14), where Nt is the number of antennas corresponding to the communication device (e.g., the transmitting device). Figure 1 The number of antennas at the transmitting end 12). In the embodiment, Nr and Nt are both not less than N, and N is the number of spatial data streams transmitted by the transmitting device. That is, the transmitting device must transmit N spatial data streams, and theoretically, the number of antennas Nt required by the transmitting device and the number of antennas Nr required by the communication device must both be greater than or equal to N. For simplicity, this invention only discusses the case where Nt = N and Nr = N, that is, an N×N multiple-input multiple-output orthogonal frequency division multiplexing system. The conclusion can also be extended and applied to Nr×Nt multiple-input multiple-output orthogonal frequency division multiplexing systems where Nt ≥ N and Nr ≥ N.

[0021] In one embodiment, interference cancellation circuit 210 cancels second inter-layer interference of the second observation signal to generate a second interference cancellation signal; based on the second interference cancellation signal, first decision circuit 220 determines a second center of a second search region (or a second concise search region); based on a second Gaussian interruption probability and a second signal-to-noise ratio, second decision circuit 230 determines a second size of the second search region; and based on the second size of the second search region, third decision circuit 240 determines a second number of at least one second candidate symbol of the second interference cancellation signal. In another embodiment, based on the second center of the second search region and the second number of at least one second candidate symbol, fourth decision circuit determines at least one second candidate symbol in the second search region; and data detection circuit detects at least one second candidate symbol to generate a second detection signal corresponding to the second observation signal. That is, when multiple observation signals exist, communication device 20 sequentially decodes the search regions of the observation signals to reduce the number of candidate symbols for each observation signal. Similarly, if a third observation signal exists (i.e., N≥3), communication device 20 decodes a third search region of the third observation signal to reduce the third number of at least one third candidate symbol for the third observation signal.

[0022] The embodiments regarding the second observation signal, second inter-layer interference, second interference cancellation signal, second search region, second center, second Gaussian interruption probability, second signal-to-noise ratio, second size, at least one second candidate symbol, and second quantity can be referred to the foregoing embodiments regarding the first observation signal, first inter-layer interference, first interference cancellation signal, first search region, first center, first Gaussian interruption probability, first signal-to-noise ratio, first size, at least one first candidate symbol, and first quantity. For example, the step of the interference cancellation circuit 210 in eliminating the second inter-layer interference of the second observation signal includes: performing SQRD decomposition on the second observation signal according to the second observation vector and the second channel matrix to eliminate the second inter-layer interference of the second observation signal. The second observation signal is located at the last element of the second observation vector, and the second channel vector corresponding to the second observation signal is located at the last column vector of the second channel matrix. Other embodiments are not described in detail here.

[0023] The following example illustrates how the communication device 20 determines the search area to reduce the complexity of multiple-input multiple-output (MIMO) data detection. Assume that the communication device 20 transmits two data streams, the MIMO is a 2×2 multiple-input multiple-output system, and the modulation / demodulation method is 16QAM with an order of 16. First, the per-tone channel matrix H and the observation signal vector of each subcarrier are defined. as follows:

[0024]

[0025] In Equation 1, SQRD decomposition is performed through the interference cancellation circuit 210. Each subcarrier channel matrix H can be decomposed into a unitary matrix Q and an upper triangular matrix R, where the matrix... r 11 and r 22 Let r be a real number. 12 It is a complex number. Q·Q H =Q H Q = I (identity matrix). x represents the data transmitted from the transmitting end, where x = [x1x2]. T , and x1 and x2 are complex numbers. The noise is for each subcarrier. Therefore, the observed signal vector y received by the interference cancellation circuit 210 is as follows:

[0026]

[0027] Where n is the noise vector. And n1 and n2 are complex numbers. The probabilities of the real part and imaginary part of n1 and n2 follow a Gaussian distribution. In the embodiment, in i = 1, 2, μ = I or Q, and σ 2 Let n1 and n2 be the power of the noise. Therefore, the search area for x2 is square. According to Equation 3, the interference cancellation circuit 210 can obtain the interference cancellation signal. As described below (Equation 4) and (Equation 5):

[0028] y2 = r 22 x² + n² (Equation 4)

[0029]

[0030] It should be noted that r 22 The larger the value, the better. The smaller the value, the better the x2 and interference cancellation signal. The smaller the error between them, the stronger the interference cancellation signal. The reduced variability of x2 also narrows the search range due to decreased uncertainty. This also illustrates the necessity of the SQRD function, which lies in determining r. 22 ≥r 11 This reduces the search range of x2. Then, through zero-force and slicing, the first decision circuit 220 performs a hard decision (e.g., selecting the closest interference cancellation signal from M candidate symbols). (candidate symbols) to generate a hard decision signal As stated in (Equation 6):

[0031]

[0032] The first decision circuit 220 will determine the hard decision signal. The center of the search area is considered as the center. Furthermore, the second decision circuit 230 determines the Gaussian interruption probability δ, and the parameter β of the Gaussian tail probability Q(β) is calculated based on the Gaussian interruption probability δ as follows:

[0033] δ=1-2Q(β) (Equation 7)

[0034] in Next, based on the parameter β and the measured signal-to-noise ratio η, the second determination circuit 230 determines the size C of the search region (i.e., half the side length of the search region), as described in (Equation 8) and (Equation 9):

[0035]

[0036] Where C>0, and σ 2 Let n1 and n2 be the power of the noise. Therefore, the size C of the search region can be expressed as follows:

[0037]

[0038] Based on the size C, the third decision circuit 240 determines the number N of candidate symbols along half the side length of the search region. c as follows:

[0039]

[0040] Where α0 is the normalization factor of 16QAM, to ensure E{|x i | 2} = 1, α0|r 22 |For interference cancellation signals in 16QAM The distance between candidate symbols (see reference) Figure 3 Therefore, the number N of candidate symbols along the edge of the search region is... μ and the number N of candidate symbols in the search area p as follows:

[0041] N μ =2N C +1 (Equation 12)

[0042]

[0043] Where M is the order of the modulation / demodulation method. In this embodiment, M = 16. Therefore, the interference cancellation signal detected by the communication device 20 The number of candidate symbols should not exceed the modulation order (M = 16). In other words, the communication device 20 does not need to detect all M candidate symbols. The complexity of detection can thus be greatly reduced, thereby improving the power saving performance of the communication device 20.

[0044] Under the same circumstances, the principle and steps of the above solution x2, after being processed by equations (Equation 14) and (Equation 15), can also be applied to the solution x1, as detailed below.

[0045] Define the channel matrix H′ for each subcarrier and the observation signal vector for each subcarrier. as follows:

[0046]

[0047] In Equation 14, SQRD decomposition is performed through interference cancellation circuit 210, and each subcarrier channel matrix H′ can be decomposed into a unitary matrix Q′ and an upper triangular matrix R′, where the upper triangular matrix... r′ 11 and r′ 22 Let r be a real number, and r′ be a real number. 12 It is a complex number. Q′·Q′ H =Q′ H Q′ = I (identity matrix). x′ represents the data transmitted from the transmitting end, where x′ = [x2 x1]. T , and x1 and x2 are complex numbers. The noise is for each subcarrier. Therefore, the observed signal vector y′ received by the interference cancellation circuit 210 is as follows:

[0048]

[0049]

[0050] Where n′ is the noise vector. According to (Equation 16), the interference cancellation circuit 210 can obtain the interference cancellation signal. As described below (Equation 17) and (Equation 18):

[0051] y1=r′ 22 x1+n1 (Equation 17)

[0052]

[0053] It should be noted that r′ 22 The larger the value, the better. The smaller the value, the better for x1 and the interference cancellation signal. The smaller the error between them, the stronger the interference cancellation signal. The reduced variability of x1 also narrows the search range due to decreased uncertainty. This underscores the necessity of the SQRD function in determining r′. 22 ≥r′ 11 This reduces the search range of x1. Then, through zero-force and slicing, the first decision circuit 220 performs a hard decision (e.g., selecting the closest interference cancellation signal from M candidate symbols). (candidate symbols) to generate a hard decision signal As stated in (Equation 19):

[0054]

[0055] The first decision circuit 220 will determine the hard decision signal. The center of the search area is considered as the center. Furthermore, the second decision circuit 230 determines the Gaussian interruption probability δ′, and the parameter β′ of the Gaussian tail probability Q(β′) is calculated based on the Gaussian interruption probability δ′ as follows:

[0056] δ′=1-2Q(β′) (Equation 20)

[0057] in Next, based on the parameter β′ and the measured signal-to-noise ratio η′, the second determination circuit 230 determines the size C′ of the search region (i.e., half the side length of the search region), as described in (Equation 21) and (Equation 22):

[0058]

[0059] Where C′>0, and σ′ 2 Let n1 and n2 be the power of the noise. The size of the search region C′ can be expressed as follows:

[0060]

[0061] Based on the size C′, the third decision circuit 240 determines the number N′ of candidate symbols along half the side length of the search region. C as follows:

[0062]

[0063] Where α0|r′ 22 |For interference cancellation signals in 16QAM The distance between candidate symbols. Therefore, the number of candidate symbols N′ along the edge of the search region. μ and the number of candidate symbols N′ in the search area p as follows:

[0064] N′μ =2N′ C +1 (Equation 25)

[0065]

[0066] Therefore, the interference cancellation signal detected by the communication device 20 The number of candidate symbols should not exceed the modulation order (M=16) and should be less than 16. In other words, the communication device 20 does not need to detect all M candidate symbols. The complexity of detection can thus be reduced, improving the performance of the communication device 20 (e.g., saving power consumption).

[0067] It should be noted that equations (1) to (26) are embodiments of a 2×2 multiple-input multiple-output system, where equations (1) to (13) are used to solve for x2 (i.e., to find the search region for x2), and equations (14) to (26) are used to solve for x1 (i.e., to find the search region for x1). The operation of the above embodiments can also be applied to N×N multiple-input multiple-output systems. For example, communication devices take turns solving for all x... n The search area is defined as n = 1 to N. The communication device alternately moves the nth observation signal (or the nth element) of the subcarrier y (e.g., y1 and y2 in the above embodiment) to the last element of the observation signal vector, and alternately moves the nth vector h n (For example, h1 and h2 in the above embodiment) are moved to the last column vector in each subcarrier channel matrix. According to the operation of the above embodiment, this is used for all x n The search area can be solved.

[0068] The following example illustrates how the communication device 20 determines the search area to reduce the complexity of multiple-input multiple-output (MIMO) data detection. Assume that the communication device 20 transmits N data streams, and MIMO is an N×N multiple-input multiple-output system. N is a positive integer greater than 1. First, the channel matrix H" of each subcarrier and the observation signal vector y" of each subcarrier are defined as follows:

[0069] H″=[h1 h2 ... h N-1 h N (Equation 27)

[0070] y″=[y1 y2 ... y N-1 y N ] T =H″x″+n″ (Equation 28)

[0071] x″ represents the data transmitted from the transmitting end, where x″ = [x1 x2 ... x N-1 x N ]T ,x1~x N It is a complex number. n″=[n1n2 ... n N-1 n N ] T , where n1~n is the noise of each subcarrier. N They have the same statistical properties (e.g., variance) and are independently and identically distributed (i.e., i.id). When communication device 20 wants to solve for x... n When searching the region, the communication device 20 performs inter-layer swap on each subcarrier channel matrix H" and each subcarrier observation signal vector y" (for example, swapping h in each subcarrier channel matrix H"). n and h N And swapping the y in the observation signal vector y" of each subcarrier n and y N The channel matrices of each subcarrier after the exchange. and the observation signal vector of each subcarrier as follows:

[0072]

[0073] In (Equation 29), SQRD decomposition is performed through interference cancellation circuit 210, and the channel matrix of each subcarrier is obtained. It can be decomposed into a unitary matrix Q″ and an upper triangular matrix R″, where R″ ≡ {r ij}, 1≤i, j≤N. If i <j,r ij =0. In (Equation 30), x″ = [x1 ... x N ... x N-1 x n ] T , and n″=[n1 ... n N ... n N-1 n n ] T In the embodiment, h1 ... h in (Equation 29) N ... h N-1 Inter-layer exchanges can be performed, and y1 ... y in (Equation 30) N ... y N-1 Inter-layer switching can be performed to reduce the size of the search area. In other words, there are many ways for communication device 20 to perform inter-layer switching. For example, when communication device 20 wants to solve for x... n When searching the area, the communication device 20 exchanges h in each subcarrier channel matrix H". n and hN Then, swap h1 and h2 in each subcarrier channel matrix H" N And the corresponding processing of the observed signal vector y for each subcarrier. For example, when communication device 20 wants to solve for x n When searching the area, the communication device 20 exchanges h in each subcarrier channel matrix H". n and h N Then, swap h1 and h2 in each subcarrier channel matrix H″. N-1 , and the corresponding processing of the observation signal vector y″ for each subcarrier.

[0074] The subsequent operation of (Equation 30) can be referred to Equations (3) to (13) and their related descriptions. Therefore, by alternately exchanging the column vectors of each subcarrier channel matrix H" and the elements of each subcarrier observation signal vector y", the communication device 20 can solve for all x n The search area. It should be noted that through different methods of inter-layer switching, the communication device 20 can obtain different switched subcarrier channel matrices. Furthermore, different upper triangular matrices R″ and different r can be calculated. NN In the upper triangular matrix R″, r NN The larger the value of x, the better. n and interference cancellation signal The smaller the error between them, the stronger the interference cancellation signal. The variability of x decreases, therefore x n The search area is narrowed. Therefore, by performing different inter-layer switching on each subcarrier channel matrix H" and each subcarrier observation signal vector y", the communication device 20 can calculate the maximum value of r. NN This reduces the size of the search area.

[0075] Figure 3 Interference cancellation signal for embodiments of the present invention A schematic diagram. In Figure 3 In the diagram, the horizontal axis represents real numbers. And the vertical axis is an imaginary number. Figure 3 Point 16 in the diagram represents the interference cancellation signal in 16QAM. The candidate symbols, and the distance between the candidate symbols is α0|r 22 According to the above embodiment, the communication device 20 determines the center CT (e.g., hard determination signal) of the search area. The center CT and size C of the search area are determined. After determining the center CT and size C of the search area, the communication device 20 obtains the search area SR. The communication device 20 only detects candidate symbols in the search area SR, thus reducing the number of candidate symbols to be detected.

[0076] The operation of the aforementioned communication device 20 can be summarized as process 40, used for multiple-input multiple-output data detection, as shown in Figure 4. Process 40 includes the following steps:

[0077] Step S400: Begin.

[0078] Step S402: Eliminate interlayer interference of the observed signal to generate an interference cancellation signal.

[0079] Step S404: Determine the center of the search area based on the interference cancellation signal.

[0080] Step S406: Determine the size of the search area based on the Gaussian interruption probability and the signal-to-noise ratio.

[0081] Step S408: Determine the number of at least one candidate symbol of the interference cancellation signal based on the size of the search area.

[0082] Step S410: End.

[0083] Procedure 400 is used to illustrate the operation of communication device 20. For details and variations of procedure 40, please refer to the foregoing description, which will not be repeated here.

[0084] The terms "first" and "second" used above are for distinguishing the relevant statements, not for restricting the order of the relevant statements. The word "determine" described in the above operation can be replaced with "compute," "calculate," "obtain," "generate," "output," "use," "choose / select," "decide," or "is configured to." The word "detect" described in the above operation can be replaced with "detect," "monitor," "receive," "sensor," or "obtain." The word "according to" described in the above operation can be replaced with "through," "by use," or "in response." The word "corresponds to" described in the above operation can be replaced with "of" or "associated with." The word "contains" described in the above operation can be replaced with "for."

[0085] It should be noted that the communication device 20 and its circuits (e.g., interference cancellation circuit 210, first decision circuit 220, second decision circuit 230, and third decision circuit 240) can be implemented in many ways. For example, the circuits in the above-mentioned device can be integrated into at least one circuit. Furthermore, the communication device 20 and its circuits can be implemented in hardware (e.g., circuits), software, firmware (a combination of hardware devices and computer instructions and data, where the computer instructions and data are read-only software on the hardware device), electronic systems, or combinations of the above devices, and are not limited thereto.

[0086] This invention provides a communication device and method. The communication device determines a search area and performs data detection only on candidate symbols within the search area. Therefore, the communication device does not detect all candidate symbols, thereby reducing the complexity of multiple-input multiple-output data detection and saving the resources of the communication device. The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made within the scope of the claims of this invention should be considered within the scope of this invention.

[0087] [Symbol Explanation]

[0088] 10: Communication System

[0089] 12: Transmission end

[0090] 14: Receiver

[0091] 20: Communication device

[0092] 210: Interlayer interference cancellation circuit

[0093] 220: First decision circuit

[0094] 230: Second Determining Circuit

[0095] 240: Third Determination Circuit

[0096] Re: Real Numbers

[0097] Im: imaginary number

[0098] SR: Search Area

[0099] CT: Center of the search area

[0100] C: Size of the search area

[0101] α0|r 22 |: Minimum distance between adjacent candidate symbols

[0102] 40: Process

[0103] S400, S402, S404, S406, S408, S410: Steps

Claims

1. A communication device comprising: Interlayer interference cancellation circuit is used to eliminate the first interlayer interference of the first observation signal to generate a first interference cancellation signal; The first determination circuit, coupled to the interlayer interference cancellation circuit, is used to determine the first center of the first search area based on the first interference cancellation signal. The second decision circuit, coupled to the first decision circuit, is used to determine the first size of the first search region based on the first Gaussian interruption probability and the first signal-to-noise ratio. as well as A third decision circuit, coupled to the second decision circuit, is used to determine the first number of at least one first candidate symbols of the first interference cancellation signal based on the first size of the first search region.

2. The communication device according to claim 1, further comprising: A fourth decision circuit, coupled to the third decision circuit, is used to determine the at least one first candidate symbol in the first search region based on the first center of the first search region and the first number of the at least one first candidate symbol; and A data detection circuit, coupled to the fourth decision circuit, is used to detect the at least one first candidate symbol to generate a first detection signal corresponding to the first observation signal.

3. The communication device according to claim 1, wherein the first observation signal comprises a multiple-input multiple-output orthogonal frequency division multiplexing signal.

4. The communication apparatus according to claim 1, wherein the step of the interlayer interference cancellation circuit eliminating the first interlayer interference of the first observation signal comprises: Based on the first observation vector and the first channel matrix, an SQRD decomposition is performed on the first observation signal to eliminate the first inter-layer interference of the first observation signal. The SQRD decomposition is a sorted QR decomposition. The first observation signal is located at the last element of the first observation vector, and the first channel vector corresponding to the first observation signal is located at the last column vector of the first channel matrix.

5. The communication device according to claim 1, wherein the step of the first determining circuit determining the first center of the first search area based on the first interference cancellation signal comprises: By employing zero-force and slicing, a hard decision is made for the first interference cancellation signal to determine the first center of the first search area.

6. The communication device according to claim 1, wherein the step of the second determining circuit determining the first size of the first search region based on the first Gaussian interruption probability and the first signal-to-noise ratio comprises: Determine the probability of the first Gaussian interruption; Based on the first Gaussian interruption probability, determine the parameter corresponding to the Gaussian tail probability; and The first size of the first search region is determined based on the parameter and the first signal-to-noise ratio.

7. The communication device according to claim 1, wherein the communication device operates in an Nr×Nt multiple-input multiple-output orthogonal frequency division multiplexing system, wherein Nr is the number of antennas of the communication device, Nt is the number of antennas of the corresponding transmission device of the communication device, both Nr and Nt are not less than N, and N is the number of spatial data streams transmitted by the transmission device.

8. The communication apparatus of claim 1, wherein the interlayer interference cancellation circuit cancels second interlayer interference of the second observation signal to generate a second interference cancellation signal; based on the second interference cancellation signal, the first determination circuit determines a second center of a second search region; based on a second Gaussian interruption probability and a second signal-to-noise ratio, the second determination circuit determines a second size of the second search region; and based on the second size of the second search region, the third determination circuit determines a second number of at least one second candidate symbol of the second interference cancellation signal.

9. The communication apparatus of claim 8, wherein the step of the interlayer interference cancellation circuit eliminating the second interlayer interference of the second observation signal comprises: Based on the second observation vector and the second channel matrix, the SQRD decomposition for the second observation signal is performed to eliminate the second inter-layer interference of the second observation signal. The SQRD decomposition is a sorted QR decomposition. The second observation signal is located at the last element of the second observation vector, and the second channel vector corresponding to the second observation signal is located at the last column vector of the second channel matrix.

10. A method for detecting multiple-input multiple-output data, comprising: To eliminate interlayer interference in the observed signal and generate an interference cancellation signal; The center of the search area is determined based on the interference cancellation signal; The size of the search region is determined based on the Gaussian interruption probability and the signal-to-noise ratio; and The number of at least one candidate symbol for the interference cancellation signal is determined based on the size of the search area.

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