WO2016209041A1

WO2016209041A1 - Mimo communication system and transceiving device therefor

Info

Publication number: WO2016209041A1
Application number: PCT/KR2016/006799
Authority: WO
Inventors: 한동석; 박명철
Original assignee: 경북대학교 산학협력단
Priority date: 2015-06-26
Filing date: 2016-06-24
Publication date: 2016-12-29

Abstract

The present invention relates to a multi input multi output (hereinafter, MIMO) communication system, and a signal transceiving device for the system. The present invention relates to a MIMO communication system and a transceiving device for the system, which can determine a transmission antenna combination, using first bit information of a transmission signal, and transmit the remaining bit information (second bit information) of the transmission signal by applying a different space time block coding (STBC) scheme and spatial multiplexing (SM) scheme, thereby providing additional bit information without increasing a bandwidth of a channel in comparison with the conventional technology.

Description

MIO communication system, and a transceiver of the system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-input multi-output (MIMO) communication system, and a signal transmitting / receiving apparatus of the system, wherein the combination of the transmitting antennas is determined using the first bit information of the transmission signal and the rest of the transmission signal. By transmitting bit information (second bit information) by applying different space time block coding (STBC) techniques and spatial multiplexing (SM) techniques, it is possible to provide additional bit information without increasing the bandwidth of the channel compared to the prior art. MIMO communication system, and a transceiver of the system.

As the demand for high-speed data transmission in a wireless environment is gradually increasing, a shortage of frequency resources is expected, and as the importance of frequency bands becomes more important, an Orthogonal Frequency Division Mulitplexing (OFDM) system that can be used by sharing frequency is the next generation. It is attracting much attention as a wireless multimedia transmission technology. In the wireless environment, as the demand for high-speed data transmission and the simultaneous connection of many users increases, a lot of researches are being conducted to enable the use of a limited frequency more efficiently. In order to solve the high link budget required in the wireless Internet, researches on a transmission diversity scheme using multiple antennas at the transmitting end have been actively conducted. The most representative of the transmit diversity schemes is the STBC technique, which shows excellent performance at low speed, but degrades due to delay caused by feedback at high speed.

The Bell Lab Layered Space Time (MIMO) method of Bell Lab Layered Space Time (BMO) proposed by Bell Lab to increase the multiplexing gain is possible. This method transmits and receives in rich scattering environment. By using multiple antennas, multiple independent fading channels can be formed and different signals can be transmitted for each transmit antenna, resulting in a significant improvement in data rate. In this case, the BLAST-OFDM scheme can be easily applied to a multipath environment because the MIMO scheme assumes flat fading having a bandwidth smaller than the coherence bandwidth of the channel. That is, the BLAST system employing the OFDM scheme has an advantage that the influence of the multipath delay is attenuated by the use of CP and approximated to a flat fading channel so that the receiver can detect a signal without using additional hardware. In addition, when using multiple transmit / receive antennas by applying V-BLAST, it is possible to effectively increase the transmission rate even with low calculation amount.

In particular, the so-called Space Time Block Coded Spatial Modulation (STBC-SM), which combines a Space Time Block Coding (STBC) technique and a Space Modulation (SM) technique, has an effect of improving spectral efficiency. Specifically, the STBC-SM technique improves bandwidth efficiency by transmitting diversity gain by using two transmit antennas.

However, the STBC-SM technique is very inefficient because it uses only two transmit antennas among a plurality of transmit antennas in terms of bandwidth efficiency. Accordingly, there is a need for a technique for improving frequency efficiency or bandwidth efficiency by utilizing other transmission antennas.

The present invention has been made to solve the above problems, MIMO communication system that can transmit additional bit information without changing the size of the bandwidth by transmitting the transmission symbol through all transmission antennas using the STBC and SM techniques , And a transceiver for the system.

In addition, through this to increase the frequency efficiency or bandwidth efficiency of the MIMO communication system to provide a MIMO communication system, the communication system efficiency is further increased, and a transceiver of the system.

MIMO communication system according to an aspect of the present invention, the transmission data input unit for receiving the transmission data consisting of the first bit information and the second bit information; A mapping selector for determining a combination of transmit antennas based on first bit information of the transmit data; A plurality of STBC (Space Time Block Coding) encoding units for dividing and modulating the second bit information into a plurality of pieces, and encoding the modulation information by STBC (Space Time Block Code) by rotating phases of each modulation information by different angle components; A transmission antenna unit for transmitting the signal information encoded through the plurality of STBC encoding units according to a transmission antenna combination determined by the mapping selection unit; A reception antenna unit for receiving signal information transmitted from the transmission antenna unit; A mapping detector for detecting a combination of transmit antennas using the received signals and detecting first bit information corresponding thereto; A plurality of STBC decoding units for dividing the received signal information into a plurality of STBCs according to the sensed transmission antenna combinations and decoding the same by STBC (Space-Time Block Coding) and rotating by different angle components to detect second bit information; And a reception data output unit configured to output transmission data using the first bit information and the second bit information.

In this case, the size of the first bit information may be set corresponding to the number of antennas of the transmitting antenna unit.

The mapping detector may detect a combination of transmit antennas using phase information of signals received through the receive antennas including a plurality of receive antennas.

According to another aspect of the present invention, a transmission apparatus of a MIMO communication system includes: a transmission data input unit configured to receive transmission data including first bit information and second bit information; A mapping selector for determining a combination of transmit antennas based on first bit information of the transmit data; A plurality of STBC (Space Time Block Coding) encoding units for dividing and modulating the second bit information into a plurality of pieces, and encoding the modulation information by STBC (Space Time Block Code) by rotating phases of each modulation information by different angle components; And a transmission antenna unit for transmitting the signal information encoded through the plurality of STBC encoding units according to the transmission antenna combination determined by the mapping selection unit.

In addition, the modulation method of the second bit information and different angular component values may be set by a user.

Receiving apparatus of the MIMO communication system according to another aspect of the present invention, the receiving antenna unit for receiving the transmitted signal information; A mapping detector for detecting a combination of transmit antennas using the received signals and detecting first bit information corresponding thereto; A plurality of STBC decoding units for dividing the received signal information into a plurality of STBCs according to the sensed transmission antenna combinations and decoding the same by STBC (Space-Time Block Coding) and rotating by different angle components to detect second bit information; And a reception data output unit configured to output transmission data using the first bit information and the second bit information.

In this case, the mapping detector may detect a combination of transmit antennas using phase information of signals received through the receive antennas including a plurality of receive antennas.

MIMO communication system according to a preferred embodiment of the present invention, and the transceiver of the system determines a combination of the transmission antenna based on the first bit information of the transmission data to be transmitted, and the second bit information which is the remaining bit information of the transmission data Is modulated into a plurality of pieces, and the phase of each modulation information is rotated by different angular components to be encoded by STBC, and by transmitting and receiving the encoded signal according to the determined transmission antenna combination to transmit meaningful information using all transmission antennas. There is an effect of increasing the communication efficiency.

In addition, the present invention has the effect that it is possible to transmit additional bit information without expanding the bandwidth through the above technical configuration.

1 is a diagram showing a MIMO communication system according to the present invention;

2 illustrates an embodiment of a MIMO communication system applicable to the present invention;

3 is a diagram illustrating a simulation result of the MIMO communication system according to FIG. 2 and a conventional communication technique.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to be limited to the particular embodiment of the present invention, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a MIMO communication system according to the present invention.

As shown in FIG. 1, the MIMO communication system according to the present invention includes a transmission data input unit 10 that receives transmission data composed of first bit information and second bit information; A mapping selector 20 for determining a combination of transmit antennas based on first bit information of the transmit data; A plurality of space time block coding (STBC) encoding units 30 which modulate the second bit information into a plurality of pieces and rotate the phases of each modulation information by different angle components to encode the second bit information into space time block codes (STBCs); ; A transmission antenna unit (40) for transmitting the signal information encoded by the plurality of STBC encoding units (30) according to the transmission antenna combination determined by the mapping selection unit (20); A receiving antenna unit 50 for receiving signal information transmitted from the transmitting antenna unit 40; A mapping detector 60 for detecting a combination of transmission antennas using the received signals and detecting first bit information corresponding thereto; A plurality of STBC decoding units (70) for dividing received signal information into a plurality of STBCs according to the sensed transmission antenna combinations and decoding the same by STBC (Space-Time Block Coding) and rotating the components by different angle components to detect second bit information; And a reception data output unit 80 that outputs transmission data using the first bit information and the second bit information.

In this embodiment, in the embodiment applicable to the present invention, the number of transmitting antennas A and the number of receiving antennas B may be applied, and as A and B values, all values corresponding to 2 ^ k (k is an arbitrary natural number) Can be applied.

The transmission data input unit 10 receives the transmission data including the first bit information and the second bit information, and classifies the bit information to provide the mapping selection unit 20 and the plurality of STBC encoding units 30. In this case, upper bit information of the transmission data may be applied as the first bit information, and bit information other than the first bit information of the transmission data may be applied as the second bit information.

The mapping selector 20 determines a combination of transmit antennas based on the first bit information. In this case, the size of the first bit information may be set corresponding to the A value of the number of transmission antennas. For example, when the A value is 4, the size of the first bit information may be set to 2 bits, and when 8, the size of the first bit information may be set to 3 bits. As such, if the number of transmitting antennas is 2 ^ a, the size of the first bit information may be set to a bits.

The mapping selector 20 determines the transmission antenna combination through the first bit information as described above. In the above embodiment, when the size of the first bit information is set to a bits, one of the transmission antenna combinations may be determined according to the value of the first bit information among a total of 2 ^ a transmission antenna combinations. For example, when the value of the first bit information is 1, each signal encoded by the first STBC encoder 30-1 to the N-th STBC encoder 30-N is sequentially transmitted to the first antenna of the transmit antenna unit. A transmission antenna may be allocated to the Nth transmission antenna and transmitted. On the contrary, when the value of the first bit information is 2 ^ a, each signal encoded by the first STBC encoding unit 30-1 to the Nth STBC encoding unit 30-N is transmitted to the transmission antenna unit 40, respectively. ) May be allocated backwards to the Nth transmit antenna to the first transmit antenna.

In the present invention, each STBC encoding section 30 includes a modulation section 31, STBC module 33, each STBC encoding section 30 is a phase rotation section 32 for rotating the phase information by different angle components ). In this case, the phase rotation component of the first STBC encoding unit 30-1 is 0 rad, and a separate phase rotation unit 32 may not be substantially applied as shown in FIG. 1. Accordingly, the MIMO communication system according to the present invention can be configured to include a total of N-1 phase rotation unit 32 as shown in FIG.

Hereinafter, the STBC encoding unit 30 will be described in detail through the respective technical components.

The second bit information of the transmission data is sequentially transmitted to the first modulator 31-1 to the N-th modulator 31 -N. Subsequently, each modulator 31 performs data modulation on signal information input (transmitted) based on a modulation method determined according to a user's input or setting. In this case, as a data modulation method, Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulatijon (16-QAM), Quadrature Amplitude Modulatijon (64-QAM), and the like may be applied.

The signal information modulated by the second to Nth modulators 31 is provided to corresponding phase rotation units 32, respectively. In this case, the signal information modulated by the first modulator 31-1 may be provided to the first STBC module 33-1 without additional phase rotation.

The first phase rotating part 32-1 to the N-th phase rotating part 32-(N-1) rotate the phase of the transmitted signal information by a predetermined angle component. For example, the first phase rotation unit 32-1 rotates the transmitted signal information by θ (rad), and the N-1 phase rotation unit 32-(N-1) transmits the transmitted signal information (N). -1) * θ (rad) can be rotated. Accordingly, the phase information rotated by each phase rotation unit 32 may be set differently.

The first to N-th STBC modules 33 encode each transmitted signal information by STBC (Space Time Block Coding). In detail, the first to N-th STBC modules 33 generate a space-time block code by blocking each signal to be transmitted by antenna and time. The space-time block code is defined by a transmission matrix G of size P * n _T. Here, p is the length of the space-time block code, and n _T is the number of transmit antennas. G consists of a linear combination of signals (symbols) to be transmitted and their conjugate complex numbers.

As an example, the transmission matrix G in the STBC system having a length of a space time block code of 2 and two transmitting antennas may be applied as in Equation 1 below.

The transmission antenna combination information l determined by the mapping selecting unit 20 and the signal (symbol) information encoded by each STBC encoding unit 30 are transmitted to the transmission antenna unit 40. Subsequently, the transmission antenna unit 40 transmits the signal information encoded through the first through N-th STBC modules according to the transmission antenna combination determined by the mapping selection unit.

The receiving antenna unit 50 receives signal information transmitted from the transmitting antenna unit 40 including the plurality of transmitting antennas.

The mapping detector 60 detects a combination of transmit antennas by using signal information received through the receive antenna unit 50 and detects first bit information corresponding thereto. In an embodiment applicable to the present invention, the mapping detection unit 60 may detect a combination of transmission antennas by using phase information of signals received through the reception antenna unit 50 including a plurality of reception antennas. . As an example, the mapping detector 60 may detect a combination of transmit antennas using a maximum likelihood (ML) detection method.

The signal information received according to the transmission antenna combination detected by the mapping detector 60 is divided into a plurality of pieces and provided to the first to Nth STBC decoding units 70. At this time, the first to N-th STBC decoding units 70 respectively decode the received signal information into STBC and rotate by a predetermined angle component to detect the second bit information.

In an exemplary embodiment, the second STBC decoding unit 70-2 may decode the transmitted signal information into STBC, and detect the corresponding signal information by reversely rotating by θ (rad). Similarly, the N-th STBC decoding unit 70-N decodes the transmitted signal information into STBC, and reversely rotates by (N-1) * θ (rad) to detect corresponding signal information. On the other hand, the first STBC decoding unit 70-1 may decode the transmitted signal information into the STBC and detect corresponding signal information without additional phase rotation.

As described above, the angular component value at which the first through N-th STBC decoding units 70 rotate the phase of the decoded signal information to detect the signal information is transmitted to the first through N-th STBC encoders 30 of the transmitter. Can be set correspondingly.

The reception data output unit 80 outputs transmission data by using the first bit information and the second bit information provided from the mapping detector 60 and the first to N th STBC decoding units 70.

In the embodiment of the present invention, only the forward transmission / reception method of the transceiver in the MIMO communication system has been described. However, since the reverse system structure differs only in the roles of the forward and reception devices, the configuration and method thereof are not the same.

Hereinafter, the configuration of the MIMO communication system according to the preferred embodiment applicable to the present invention and the difference between the system and the conventional communication method will be described with reference to FIGS. 2 and 3.

2 is a diagram illustrating an embodiment of a MIMO communication system applicable to the present invention.

As shown in FIG. 2, the transceiver of the MIMO communication system according to the present invention includes two STBC encoders 230 and STBC decoders 270, respectively. Accordingly, four transmit antennas may be configured. have.

Hereinafter, descriptions overlapping with the above descriptions will be omitted.

According to the embodiment of FIG. 2, first bit information having a size of 2 bits among the transmission data input to the transmission data input unit 210 is provided to the mapping selector 220. In addition, the second bit information may be encoded as S ₁ and S ₂ provided through the first STBC encoding unit 230-1 and the second STBC encoding unit 230-2. Can be represented as:

Here, S _i is a transmission matrix of the i-th STBC encoder 230 and sij means a j-th input signal (symbol) of the i-th STBC encoder 230. In this case, a row denotes an order of a transmitting antenna, and a column denotes a symbol duration. ( ^* ) ^* Means complex conjugate.

The transmission antenna unit 240 according to the present invention transmits a transmission signal as shown in Equation 3 below according to the transmission antenna combination information l provided from the mapping selection unit 220.

Here, in X ₁ , l = 1,2,3,4, and means a transmission signal matrix having a size of N _t * 2. In this case, N _t means the number of transmit antennas, and the column of the matrix means 2 symbol periods. Such a transmission signal matrix is determined by the transmission antenna combination information l.

In this case, the mapping selecting unit 220 determines the transmission antenna combination information l based on the first bit information. The mapping selection unit 220 may determine the transmission antenna combination information l by the following method. For example, when the first bit information is 00, the transmission antenna combination information l may be determined as 1. Alternatively, when the first bit information is 11, the transmission antenna combination information (l) value may be determined as 4.

As such, the spectral efficiency according to the number of transmission antenna combinations c determined by the mapping selector 220 may be expressed by Equation 4 below.

Here, m denotes a spectral efficiency value, and M denotes a modulation order.

The transmission antenna combination information 1 determines a transmission antenna for transmitting the encoded (encoded) signal information through each STBC encoding unit 230. For example, when the transmission antenna combination information (l) has a value of 1, the signal (symbol) S ₁ encoded through the first STBC encoding unit 230-1 is transmitted through the first and second transmission antennas, The signal (symbol) S ₂ encoded through the second STBC encoding unit 230-2 is transmitted through the third and fourth transmission antennas. Accordingly, according to the present invention, additionally 2 bits of information can be transmitted for 2 symbol durations without additional bandwidth.

A signal transmitted and received through the MIMO communication system according to the present invention may be represented by Equation 5 below.

Here, Y denotes a received signal matrix having a size of N _r * 2, and N _r denotes the number of receive antennas. H is a random matrix of size N _r * N _t , and each entry has an average value of 0 and has an independent and identically distributed Gaussian random variable distribution. N is a noise matrix of size N _r * 2, and each entry has a value of 0 and an variance of σ _N ² . In this case, the transmission signals (symbols) have a unit energy (for example,

Is assumed.

The transmitter of the MIMO communication system according to the present invention transmits the signal encoded through the second STBC encoder 230-2 by rotating a predetermined angle phase so that the receiver can detect a combination of transmit antennas. In this case, as the phase rotation value of the second STBC encoder 230-2, a rotation angle value for maximizing an Euclidean distance between the received signals (symbols) may be applied.

For example, an optimal rotation angle value may be determined as shown in Equation 6 below according to the signal modulation scheme of the first and second modulators.

The receiving device according to the present invention may receive signal information as shown in Equation 7 through the receiving antenna unit 250.

If Equation 7 is simply shown, it can be expressed as Equation 8 below.

Where s is a transmitted signal vector of size N _t * 1, y is a received signal vector of size 2N _r * 1, n is a transmitted Gaussian noise vector of size 2N _r * 1, H _l is 2N _r * N _t Decoding channel matrix of size.

In the transmission apparatus according to the present invention, since the signals encoded by the first STBC encoder 230-1 and the second STBC encoder 230-2 are rotated in phases different from each other, the mapping detector 260 is According to Equation 9 below, a transmission antenna combination (l) value may be detected.

Where ml is the lth minimum ML metric for all s combinations. In this case, the mapping detector may detect the transmit antenna combination l by selecting the minimum metric satisfying Equation 10 below.

here,

Denotes the estimated transmit antenna combination value.

The second bit information may be detected by Equation 11 below through the first STBC decoding unit 270-1 and the second STBC decoding unit 270-2 according to the detected transmission antenna combination value. .

here,

Denotes the j-th detected signal (symbol) of the i-th STBC encoding unit.

Hereinafter, the advantages of the MIMO communication system as compared to the conventional communication method will be described with reference to FIG. 3.

In the simulation, we assume that the channel is perfect, and assume that the channel coefficient follows the Rayleigh fading distribution. In addition, it is assumed that a direct ML detector is applied to the mapping detector according to the present invention. At this time, the MIMO communication system according to the present invention is referred to as DSTTD-SM for convenience.

Figure 3 shows the performance of the prior art according to Alamouti STBC, OSTBC 3/4, SM, STBC-SM, DSTTD and the MIMO communication system (DSTTD-SM) according to the present invention at a spectral efficiency of 3 bits / s / Hz. Indicates. In this case, it is assumed that the STBC communication technique uses two transmit antennas and the other communication techniques utilize four communication antennas. In addition, it is assumed that all communication techniques utilize four receive antennas.

As shown in FIG. 3, the reception performance of the MIMO communication system according to the present invention is superior to other communication techniques. Specifically, the BER (Bit Error Rate) value is 10 ^-3 and has superior characteristics compared to other communication techniques.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

Claims

A transmission data input unit configured to receive transmission data including first bit information and second bit information;

A mapping selector for determining a combination of transmit antennas based on first bit information of the transmit data;

A plurality of STBC (Space Time Block Coding) encoding units for dividing and modulating the second bit information into a plurality of pieces, and encoding the modulation information by STBC (Space Time Block Code) by rotating phases of each modulation information by different angle components;

A transmission antenna unit for transmitting the signal information encoded through the plurality of STBC encoding units according to a transmission antenna combination determined by the mapping selection unit;

A reception antenna unit for receiving signal information transmitted from the transmission antenna unit;

A mapping detector for detecting a combination of transmit antennas using the received signals and detecting first bit information corresponding thereto;

A plurality of STBC decoding units for dividing the received signal information into a plurality of STBCs according to the sensed transmission antenna combinations and decoding the same by STBC (Space-Time Block Coding) and rotating by different angle components to detect second bit information; And

And a reception data output unit configured to output transmission data using the first bit information and the second bit information.
The method of claim 1,

The size of the first bit information is set corresponding to the number of antennas of the transmitting antenna unit.
The method of claim 1,

The mapping detector,

And a transmission antenna combination using phase information of signals received through the reception antenna unit including a plurality of reception antennas.
A transmission data input unit configured to receive transmission data including first bit information and second bit information;

A mapping selector for determining a combination of transmit antennas based on first bit information of the transmit data;

A plurality of STBC (Space Time Block Coding) encoding units for dividing and modulating the second bit information into a plurality of pieces, and encoding the modulation information by STBC (Space Time Block Code) by rotating phases of each modulation information by different angle components; And

And a transmission antenna unit configured to transmit signal information encoded through the plurality of STBC encoding units according to a combination of transmission antennas determined by the mapping selection unit.
The method of claim 4, wherein

The size of the first bit information is set according to the number of antennas of the transmitting antenna unit for the MIMO communication.
The method of claim 4, wherein

And a method of modulating the second bit information and different angular component values can be set by a user.
A receiving antenna unit for receiving the transmitted signal information;

A mapping detector for detecting a combination of transmit antennas using the received signals and detecting first bit information corresponding thereto;

A plurality of STBC decoding units for dividing the received signal information into a plurality of STBCs according to the sensed transmission antenna combinations and decoding the same by STBC (Space-Time Block Coding) and rotating by different angle components to detect second bit information; And

And a reception data output unit configured to output transmission data by using the first bit information and the second bit information.
The method of claim 7, wherein

The mapping detector,

And a transmission antenna combination is detected using phase information of signals received through the reception antenna unit including a plurality of reception antennas.