KR20100035203A - Controlling method of multi input multi output system - Google Patents

Abstract

PURPOSE: A controlling method of a multi input multi output system are provided to secure a high speed transmission effect of massive data in a multi Input and a multi Input communication system. CONSTITUTION: A receiver receives transmission data of M transmission antennas(S500). The receiver sets detection sequence according the low error probability sequence of transmission antenna(S520). The receiver detects the received data of i th transmission antenna in MMSE(Minimum Mean-Square Error) mode(S530). The receiver detects the(k+1) -th received data of i+1 antenna excepting the detected data k(S540).

Description

Controlling method of multi input multi output system

An embodiment of the present invention relates to a control method of a multiple input / output communication system.

Recent wireless communication technologies aim at various multimedia communications. Accordingly, as a method for increasing a transmission speed at a given bandwidth for high-speed data transmission, research on a multiple input multiple output (MIMO) system has been actively conducted. MIMO technology can increase the channel capacity within a limited frequency resource by using multiple antennas at both ends of the transmission and reception.

MIMO technology includes diversity technology and multiplexing technology. Diversity technology includes a space-time coding (STC) technology configured to obtain a space-time diversity gain using multiple transmit / receive antennas. Multiplexing technology includes a BLAST (Bell-lap Layered Space-Time) technology that transmits different data to each transmit antenna. Recently, D-STTD (Double-Space Time Transmit Diversity) technology has been developed to achieve the effects of diversity technology and multiplexing technology.

D-STTD technology is a combination of spatial multiplexing technology and STTD technology, and uses two space-time block codes (STBCs) each having a pair of antennas. D-STTD applies STTD by first creating two symbol strings by spatial multiplexing and assigning two antenna pairs to each symbol string. Therefore, a total of four transmit antennas are required for spatial multiplexing and STTD application, and two or more receive antennas are required to detect spatial multiplexed symbols. Since the D-STTD technology transmits four symbols during two symbol intervals, the same data rate as the spatial multiplexing technique using two transmit antennas can be obtained. In addition, since each antenna of the two pairs is used for the STTD, it has the same transmit diversity gain as the conventional STTD.

The received signal detection method of the system to which the D-STTD technology is applied includes a linear ZF (Zero Forcing) algorithm, a linear minimum mean squared error (MMSE) algorithm, a nonlinear ZF algorithm, a nonlinear MMSE algorithm, and the like. Various algorithms are known. However, in order to guarantee a high speed transmission effect of a large amount of data, there is a need for an efficient method of detecting a received signal capable of processing a received signal at high speed.

An embodiment of the present invention provides a control method of a multiple input / output communication system.

An embodiment of the present invention provides a control method of a multi-input and output communication system capable of ensuring a high speed transmission effect of a large amount of data.

A control method of a multi-input / output communication system according to an embodiment of the present invention includes: receiving data transmitted through M transmit antennas, coded in a double-space time transmit diversity (D-STTD) scheme, using N receive antennas; Detecting the received data in an OSIC-MMSE (Ordered Successive Interference Cancellation-Minimum Mean-Square Error) scheme and parallelizing the received data into M received data; And decoding the parallelized received data according to a data modulation and coding method applied to the received data.

According to an embodiment of the present invention, it is possible to ensure a high speed transmission effect of a large amount of data in a multi-input and output communication system.

Hereinafter, a control method of a multi-input / output communication system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, in describing the embodiments of the present invention, when it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

According to an embodiment of the present invention, a multiple input / output communication system to which a control method is applied includes a plurality of modulation schemes according to an MCS level of an adaptive modulation and coding (AMC) scheme. (Modulation Scheme) and a plurality of coding rates are supported. The combination of coding rate and modulation scheme is called a Modulation and Coding Scheme (MCS), and a plurality of MCS levels may be defined from level 1 to level n according to the number of MCSs.

Table 1 below shows the MCS level configuration according to the high-speed downlink packet access (HSDPA) and 3G LTE standards.

TABLE 1

As shown in Table 1, MCS levels are assigned higher order modulation schemes and higher coding rates from MCS level 1 (QPSK, Turbocode 1/3) to MCS level 4 (64QAM, Turbocode 1/2). Can be set to The higher order modulation method and the coding rate have the advantage of better data rate than the lower order modulation method and the coding rate, and the lower order modulation method and the coding rate have the advantage of low error rate. Therefore, when the channel condition is good, a higher order modulation method and a higher coding rate (eg, MCS level 4) may be selected, and as the channel condition worsens, a lower order modulation method and a coding rate (eg, MCS level 1) may be selected. .

Here, the channel state may be estimated according to a signal to noise ratio (SNR), and it is possible to apply an MCS level corresponding to a preset SNR range. For example, it is possible to set MCS level 1 to be selected when the SNR range is -10 dB to -5 dB, and to set MCS level 4 when it is +10 dB or more. Criteria for setting the MCS level may be variously set according to each system.

1 is a control block diagram illustrating a multiple input / output communication system to which a control method according to an embodiment of the present invention is applied.

As shown in FIG. 1, the multi-input / output communication system decodes a received signal in a double-space time transmit diversity (D-STTD) scheme to estimate a forward channel state, and estimates at the receiver 200. A transmitter 100 for selecting an MCS level according to the selected forward channel state, coding and modulating transmission data of the forward channel according to the selected MCS level, and then transmitting a transmission symbol to M transmission antennas (Tx) through D-STTD coding. It includes. Here, the receiver 200 may be located in a mobile terminal, and the transmitter 100 may be located in a base station.

The receiver 200 uses the D-STTD decoder 350 to decode the received symbols received through the N receive antennas Rx by the D-STTD method, and the forward channel state by using the D-STTD decoded received symbols. A channel state estimator 240 for estimating signal to noise ratio (SNR), a demodulator 230 for demodulating a D-STTD decoded received symbol, and a channel deinterleaving channel demodulated with the demodulated received bit data. An interleaver 220 and a decoder 210 for decoding the channel deinterleaved bit data and outputting the received data.

The transmitter 100 includes an MCS level selector 140 that selects an MCS level according to the forward channel state information estimated by the channel state estimator 240, and transmits data according to the MCS level selected by the MCS level selector 140. An encoder 110 for coding, a channel interleaver 120 for channel interleaving the coded transmission bit data according to the MCS level, a modulator 130 for modulating the channel interleaved transmission bit data according to the MCS level, D-STTD encoder 300 for D-STTD coding the modulated transmit symbol. Here, the MCS level selector 140 may be included in the transmitter 100 or may be included in the receiver 200, but the present embodiment describes a case in which the MCS level selector is included in the transmitter 100.

The modulator 130 and the demodulator 230 of the transmitter 100 and the receiver 200 may modulate and demodulate a signal using QPSK, 16QAM, and 64QAM modulation schemes.

The encoder 110, the channel interleaver 120, the decoder 210, and the channel deinterleaver 220 may perform channel coding and channel decoding using turbo coding methods having coding rates 1/3 and 1/2.

The channel state estimator 240 of the receiver 200 estimates the SNR, which is the state information of the forward channel, by using the received symbol demodulated by the D-STTD decoder 350. The channel state estimator 240 feeds back the estimated SNR of the forward channel to the transmitter 100.

The MCS level selector 140 of the transmitter 100 selects the MCS level according to the forward channel state fed back from the receiver 200. In accordance with the selected MCS level, encoder 110, channel interleaver 120, and modulator 130 channel code and modulate the transmission data. The modulated transmission data is coded in the D-STTD encoder 300 and transmitted to the M transmit antennas Tx. The MCS level selector 140 selects a higher order modulation method and a higher coding rate (eg, MCS level 4) when the channel condition is good, and as the channel condition worsens, the lower order modulation method and the coding rate (eg, MCS level 1). Can be selected.

With this configuration, the transmission data undergoes the channel coding and interleaving process selected by the MCS level selector 140 and then undergoes a modulation process according to the modulation technique selected by the MCS level selector 140 as well. The transmission symbols completed until the modulation process are encoded by the D-STTD encoder 300 and transmitted through the M transmit antennas (Tx). The signal passing through the channel is converted by the receiving end through the D-STTD decoder 350 to an estimated value of the original symbol. The estimated value of the received signal is restored to the original signal through the demodulator 230, the channel deinterleaver 220, and the decoder 210.

2 is a control block diagram illustrating a D-STTD encoder 300 and a D-STTD decoder 350 of a multi-input / output communication system to which a control method according to an exemplary embodiment of the present invention is applied.

As shown in FIG. 2, the D-STTD technology is a method in which two STTDs are connected in parallel, and basically includes four transmitting antennas Tx and two receiving antennas Rx.

The D-STTD encoder 300 includes a demultiplexer 330 for multiplexing the modulated signal through the modulator 130 and a first STTD block for encoding the modulated signal output from the demultiplexer 330 in a D-STTD manner. 310 and the second STTD block 320.

The D-STTD decoder 350 includes an OSIC-MMSE (Ordered Successive Interference Cancellation-Minimum Mean-Square Error) detector 340 that detects a signal received by the reception antenna Rx. The signal received by the D-STTD decoder 350 may be represented by the following <formula>.

<Formula>

Here, r represents a received signal, h represents a channel response, s represents a transmission signal, and n represents noise. In the case of a channel response, it is expressed in the form of h _ij , which means a channel response between the j th transmit antenna Tx and the i th receive antenna Rx. The channel response h _ij is independent and identically distributed (iid) and follows a complex Gaussian distribution with zero mean. Noise n is Additive White Gaussian Noise (AWGN) with an average of zero and a variance of σ ² I.

According to this configuration, the D-STTD encoder 300 encodes the transmitted symbols modulated by the modulator 130 through the first STTD block 310 and the second STTD block 320 to each of four modified signals. Transmit via the transmit antenna Tx. When transmitting in the D-STTD scheme, the transmission symbol streams S1, S2, S3, and S4 are divided into two symbol streams "S1, S2", "S3, S4" through the demultiplexer 330. The symbol streams "S1, S2" are encoded in the first STTD block 310, and the symbol streams "S3, S4" are encoded in the second STTD block 320. "S1, S2" encoded in the first STTD block 310 is transmitted through two antennas, and "S3, S4" encoded in the second STTD block 320 is also transmitted through two antennas. Therefore, both the multiplexing effect of transmitting data in parallel using the first STTD block 310 and the second STTD block 320 and the diversity effect of transmitting data through the two antennas can be obtained.

The D-STTD decoder 350 receives signals transmitted from four transmit antennas Tx through two receive antennas Rx. The D-STTD decoder 350 detects the received signal using the OSIC-MMSE detector 340 and outputs the estimated symbol stream to the demodulator 230. The OSIC-MMSE detector 340 parallelizes and separates the received data by the number of transmit antennas Tx. The OSIC algorithm detects data received by the antenna of the channel with the lowest probability of error occurrence. Subsequently, the detected data is subtracted from all received data, and then repeated until all transmission data is detected in such a manner as to detect data of an antenna having a low probability of the next error occurrence.

3 is a control flowchart of a multiple input / output communication system to which a control method according to an exemplary embodiment of the present invention is applied.

The channel state estimator 240 of the receiver 200 estimates the state of the forward channel by STTD decoding the signal received through the receiving antenna Rx (S100). Here, the channel state estimator 240 may estimate the SNR which is state information of the forward channel.

The channel state estimator 240 of the receiver 200 feeds back the estimated forward channel state to the transmitter 100 (S110).

The MCS level selector 140 of the transmitter 100 selects an MCS level according to the received channel information (S120). 4 is a graph showing a simulation result of MCS level selection probability of a multi-input / output communication system. The MCS level selection probability is represented by converting the MCS level selection probability into a total probability of 1 by applying the AMC and D-STTD 4 ㅧ 2 combining system in a Rayleigh flat fading environment. As shown in FIG. 4, when the SNR is low, the probability that MCS level 1 is selected is the highest. That is, when the channel condition is not good, the third turbo coding and the QPSK modulation method having a relatively low order modulation and a low coding rate are used. On the other hand, when the SNR is high, the probability that MCS level 4 is selected is the highest. That is, when the channel condition is good, a half turbo coding and a 64QAM modulation scheme having a relatively higher order modulation and a higher coding rate are used.

The transmitter 100 codes and interleaves transmission data of a forward channel according to the selected MCS level (S130).

The transmitter 100 modulates transmission data of the forward channel according to the selected MCS level (S140).

The transmitter 100 encodes the modulated data in the D-STTD scheme (S150), and then transmits the modulated data in the D-STTD scheme through the transmit antenna Tx (S160).

The receiver 200 detects the received data received by the antenna by the OSIC-MMSE method (S170).

The receiver 200 demodulates the received data after decoding and deinterleaving the detected received data (S180). Here, the receiver 200 may demodulate the received data by a coding and modulation method corresponding to the MCS level according to the MCS level selected by the transmitter 100.

5 is a flowchart illustrating a control method of a multiple input / output communication system according to an exemplary embodiment of the present invention. Here, it is assumed that the multi-input and output communication system is configured in the form of a combination of AMC and M ㅧ N D-STTD.

The receiver 200 of the multiple input / output communication system receives data transmitted from M transmit antennas Tx through N receive antennas Rx (S500).

The receiver 200 may detect the received data by using the OSIC-MMSE scheme. Accordingly, the OSIC-MMSE detector 340 of the receiver 200 calculates the error probability of each of the M transmit antennas Tx (S510). In this case, the error probability may be calculated as a signal-to-interference ratio (SINR) value. Accordingly, the detection order is determined in the order of the channels having the highest SINR.

The OSIC-MMSE detector 340 of the receiver 200 sets the detection order i in order of low error probability (S520). Accordingly, the detection order is set from 1 to M for the M transmit antennas Tx.

The OSIC-MMSE detector 340 of the receiver 200 detects the received data k received from the i-th transmission antenna Tx according to the detection order by the MMSE method (S530). Therefore, the received data detected for the first time is data transmitted by the transmission antenna Tx having the lowest error probability. Here, the MMSE scheme is an algorithm for minimizing an error between the transmission vector and the estimated vector. The MMSE scheme detects an original transmission signal by removing interference of signals received at each reception antenna Rx.

The OSIC-MMSE detector 340 of the receiver 200 deletes the detected data k from all received data and detects the received data k + 1 of the i + 1 th antenna, which is the next detection order, in the remaining received data except the data k. (S540).

The OSIC-MMSE detector 340 of the receiver 200 checks whether M pieces of received data have been detected (S550), and repeats detection of received data until the number of detected pieces of received data is M.

On the other hand, if all M pieces of received data are detected, the receiver 200 decodes and demodulates the received data according to the MCS level applied to the received data and demodulates the received data into original data (S560).

As described above, the control method of the multi-input / output communication system according to the embodiment of the present invention can detect the received signal using the OSIC-MMSE method.

FIG. 6 is a graph illustrating simulation results of channel performance of a control method of a multi-input / output communication system according to an exemplary embodiment of the present invention and a conventional signal detection method.

The multi-input / output communication system applied to the simulation is an AMC and D-STTD 4 ㅧ 2 combining system using four transmit antennas (Tx) and two receive antennas (Rx). When the multiple input / output communication system transmits and receives data in a Rayleigh flat fading environment, the OSIC-MMSE detection method according to the present invention and the conventional linear MMSE detection method are illustrated.

As shown in FIG. 6, the OSIC-MMSE detection method is about 1 to 2 dB better than the linear MMSE detection method at low SNR, and in particular, the high SNR is about 3.5 dB better than the linear MMSE detection method. have.

7 is a graph showing simulation results of transmission rate performance of a conventional signal detection method and a signal detection method according to an exemplary embodiment of the present invention.

The multi-input / output communication system applied to the simulation is an AMC and D-STTD 4 ㅧ 2 combining system using four transmit antennas (Tx) and two receive antennas (Rx). When the multi-input / output communication system transmits and receives data in a Rayleigh flat fading environment, the OSIC-MMSE detection method according to the present invention is used, and a ZF (Zero-Forcing) detection method is applied. In this case, the rate performance is simulated.

As shown in FIG. 7, a difference of about 355 Kbps is shown at about 10 dB, which can be interpreted as a result generated because the OSIC-MMSE detection algorithm has superior BER or SER performance than the ZF algorithm.

Although the above description has been made based on the embodiments, these are merely examples and are not intended to limit the present invention. Those skilled in the art to which the present invention pertains may not have been exemplified above without departing from the essential characteristics of the present embodiments. It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

1 is a control block diagram illustrating a multiple input / output communication system to which a control method according to an embodiment of the present invention is applied.

2 is a control block diagram of a D-STTD encoder and a decoder of a multi-input / output communication system to which a control method according to an embodiment of the present invention is applied.

3 is a control flowchart of the multi-input and output communication system of FIG.

FIG. 4 is a graph showing simulation results of MCS level selection probability of the multi-input / output communication system of FIG. 1. FIG.

5 is a flowchart of a control method of a multiple input / output communication system according to an exemplary embodiment of the present invention.

6 is a graph showing simulation results of the channel performance of the conventional signal detection method and the signal detection method according to an embodiment of the present invention.

7 is a graph showing a simulation result of the transmission rate performance of the conventional signal detection method and the signal detection method according to an embodiment of the present invention.

Claims (7)

Receiving data transmitted through M transmit antennas, coded in a double-space time transmit diversity (D-STTD) scheme, using N receive antennas; Detecting the received data in an OSIC-MMSE (Ordered Successive Interference Cancellation-Minimum Mean-Square Error) scheme and parallelizing the received data into M received data; And decoding the parallelized received data according to a data modulation and coding method applied to the received data. The method of claim 1, Detecting the received data by OSIC-MMSE method and parallelizing the received data into M received data, Calculating each error probability of the M transmit antennas; Setting a detection order of the received data in order of the transmit antennas having the lowest error probability; Detecting received data received from each of the transmit antennas according to the detection rank; And detecting received data having a next detection rank from remaining received data other than the detected received data. The method of claim 2, And detecting the received data having the next detection rank from the remaining received data except for the detected received data, repeatedly performed until the M received data are detected. The method of claim 2, Detecting the received data received from each of the transmitting antennas according to the detection rank, And detecting the received data using an MMSE scheme. The method of claim 1, Decoding the parallelized received data according to a data modulation and coding method applied to the received data, And decoding the received data according to a modulation and coding method corresponding to a Modulation and Coding Scheme (MCS) level, which is a combination of data modulation and coding methods applied to the received data. The method of claim 5, Decoding the received data according to a modulation and coding method corresponding to a modulation and coding scheme (MCS) applied to the received data, Decoding the received data in one of 1/3 turbo coding and 1/2 turbo coding according to the selected MCS level. The method of claim 5, Decoding the received data according to a modulation and coding method corresponding to a modulation and coding scheme (MCS) applied to the received data, Demodulating the received data in any one of a QPSK, 16QAM, and 64QAM scheme according to the selected MCS level.

Images