KR20110034567A

KR20110034567A - Transmitting/receiving apparatus and method for improving a throughput in a multi input multi output communication system

Info

Publication number: KR20110034567A
Application number: KR1020100093476A
Authority: KR
Inventors: 정영석; 임종한; 김성수
Original assignee: 삼성전자주식회사
Priority date: 2009-09-28
Filing date: 2010-09-27
Publication date: 2011-04-05

Abstract

PURPOSE: A transmission/reception apparatus and method for improving throughput in a multi-input multi-output communication system are provided to improve the potential throughput of an SIC receiver by controlling a transceiving unit. CONSTITUTION: A transmitter includes an MCS(Modulation and Coding Scheme) selector(101), a first CRC(Cyclic Redundancy Check) error adder(103), a first FFC(Forward Error Correction) encoder(105), a first modulator(107), a resource allocator(109), a first IFFT(Inverse Fast Fourier Transform) unit(111), an S/P(Serial-to-Parallel) converter(113), a second CRC error adder(115), a third CRC error adder(117), a second FEC encoder(119), a third FEC encoder(121), a first rate matcher(123), a second rate matcher(125), a second modulator(127), a third modulator(129), a precoder(131), and a second IFFT unit(133). Upon receipt of CQI feedback information(100) of each user, the MCS selector determines an MCS level for each user's transport block based on the received CQI feedback information 100, and then outputs the MCS level to the first CRC error adder, an FEC encoding block, a rate-matching block, and a modulation block. The first CRC error adder generates a control signal to be transmitted to a receiver by integrating the MCS level of each user's transport block and each user's control information, adds to the control signal a CRC code for detecting an error occurring in a transmission process, and outputs the CRC-added control signal to the first FEC encoder. The first FEC encoder receives a signal output from the first CRC error adder, performs thereon FEC encoding for correcting an error occurring due to noise, using an FEC code, and outputs the FEC-encoded signal to the first modulator. There is no limit on the type of the FEC code. The first modulator receives a signal output from the first FEC encoder, maps the received signal to a signal constellation point, and outputs the mapped signal to the resource allocator.

Description

Transmitting and Receiving Device and Method for Improving Throughput in Multi-Input and Multi-Output Communication System {TRANSMITTING / RECEIVING APPARATUS AND METHOD FOR IMPROVING

The present invention relates to a transmission and reception apparatus and method for improving throughput in a multi-input multi-output (MIMO) communication system.

Next-generation communication systems have introduced MIMO schemes to increase the capacity of wireless channels operating with limited frequency resources. Recently, the Long Term Evolution (LTE) standard or the Wireless Broadband (WiBro) standard is based on the MIMO scheme. have.

In addition, the next-generation communication system increases frequency efficiency by adaptively assigning modulation orders and error correction codes to channels between a transmitting and receiving end through an adaptive modulation and coding (AMC) scheme. Meanwhile, in the receiver, a successive interference cancellation (SIC) scheme using a decoding result of one transmission layer is used to improve reception performance and increase system throughput.

FIG. 1 is a diagram illustrating a structure of a transmitter precoded with a large delay cyclic delay diversity (CDD) in a MIMO communication system. The large delay CDD is reflected in an open loop spatial multiplexing scheme, which is a technique for distributing a transmission layer to all virtual antennas, and reduces the amount of feedback channel quality information (CQI) and accuracy of feedback. Has a strong advantage in.

Referring to FIG. 1, a transmitter includes a modulation and coding scheme (MCS) selector 101, a first cyclic redundancy check error adder 103, and a first forward error correction. (FEC: Forward Error Correction) encoder 105, first modulator 107, resource allocator 109, first inverse fast Fourier transform (IFFT) A transform unit 111, a serial to parallel transform unit 113, a second CRC error adding unit 115, a third CRC error adding unit 117, a second FEC coder 119, The third FEC coder 121, the first rate matching unit 123, the second rate matching unit 125, the second modulator 127, the third modulator 129, the precoding unit 131 and a second IFFT unit 133.

First, if the CQI feedback information 100 of each user is input to the MCS selector 101, the MCS selector 101 based on the input CQI feedback information 100, MCS level for each user's transport block Is determined and then output to the first CRC error adder 103, the FEC coder 118, the rate matcher 122, and the modulator 126. Here, the transport block represents an independent information block to be encoded. In FIG. 1, it is assumed that two transport blocks and the transport block and the codeword are the same.

The first CRC error adding unit 103 generates a control signal to be transmitted to the receiver by integrating the MCS level of each user's transport block and the control information 110 of each user, and detects an error generated in the transmission process. The CRC code is added to the control signal and then output to the first FEC coder 105.

The first FEC coder 105 receives the signal output from the first CRC error adder 103 and performs FEC encoding to correct an error caused by noise using the FEC code, and then modulates the first signal. Output to the unit 107. There is no restriction on the FEC code, and convolutional codes or trellis codes are generally used as FEC codes for CQI feedback information.

The first modulator 107 receives the signal output from the first FEC coder 105, maps it to a signal constellation point, and outputs the signal to the resource allocator 109.

Meanwhile, when the traffic information 120 of each user is input to the serial / parallel converter 113, the serial / parallel converter 113 may convert the input traffic information 120 to the number of transport blocks of each user (ie, 2). And the two classified traffic information are output to the second and third CRC error adding units 115 and 117, respectively. The second and third CRC error adding units 115 and 117 add CRC codes for detecting an error occurring in a transmission process, and then output them to the second and third FEC coders 119 and 121, respectively. The second and third FEC coders 119 and 121 receive signals output from the second and third CRC error adders 115 and 117, respectively, to correct an error caused by noise using the FEC code. The FEC encoding is performed and then output to the first and second rate matching units 123 and 125, respectively. There is no restriction on the FEC code, and in general, a convolutional code, a turbo code, or a low density parity check (LDPC) code is used as the FEC code for traffic information.

The first and second rate matching units 123 and 125 receive signals output from the second and third FEC encoders 119 and 121, respectively, and a modulation symbol in which the number of bits of the input signal is assigned to each user. Rate matching is performed to match the number of and output to the second and third modulators 127 and 129, respectively.

The second and third modulators 127 and 129 receive the signals output from the first and second rate matching units 123 and 125, respectively, and map the signals to the signal constellation points to output to the precoding unit 131.

The precoding unit 131 receives the signals output from the second and third modulators 127 and 129, respectively, and precodes the traffic channel signal by precoding according to a predetermined rule, for example, a large delay CCD method. It is then output to the resource allocation unit 109. Here, the modulation order used by the second and third modulators 127 and 129 is determined according to the MCS level determined by the MCS selector 101, and the CRC error used in the feedback information 100 and the traffic information 120 is determined. The adder, the FEC coder, and the modulator generally use different types.

The resource allocator 109 rearranges the traffic channel signal, the control channel signal, and the pilot signal, and adjusts the power levels of the respective channels according to the power ratio that can guarantee the reception performance of each channel and applies them to the rearranged signals. Next, output to the first and second IFFT units 111 and 133. The first and second IFFT units 111 and 133 convert the frequency axis signal output from the resource allocator 109 into a time axis signal and then output the same through the transmitting antenna.

FIG. 2 is a diagram corresponding to a transmitter of FIG. 1 and illustrating a structure of a receiver (hereinafter, referred to as an "SIC receiver") to which an SIC scheme is applied in a MIMO communication system.

2, the SIC receiver includes a first Fast Fourier Transform (FFT) unit 201, a second FFT unit 203, a resource deallocator 205, and a layer ordering unit (FFT). layer odering (207), equivalent channel generation unit (209), MIMO demodulator (211), rate dematching unit (213), FEC decoder (215) CRC error detector 217, control channel detector 219, CQI metric generator 221, CQI generator 223, FEC encoder 231, rate matcher 233, and modulator ( 235). On the other hand, since the configuration except for the CQI metric generator 221 and the CQI generator 223 is for receiving a signal, it may be collectively referred to as a signal receiver.

The first and second FFT units 201 and 203 convert the time base signals received through the receiving antenna into frequency base signals and output them to the resource role assigning unit 205. The resource role assigning unit 205 receives the signals output from the first and second FFT units 201 and 203 and divides them into a traffic channel signal and a control channel signal, and the traffic channel signal is MIMO through the equivalent channel generator 209. The demodulator 211 outputs the control channel signal to the control channel detector 219.

The control channel detector 219 uses the control channel signal and the channel estimation value output by the resource role assigning unit 205, MCS level of each user's transport block, and resource allocation information of the traffic channel required for receiving the traffic channel signal. It detects the number of transport layers, whether to retransmit, and delivers them to the required blocks. In particular, the control channel detector 219 detects the MCS level of each user's transport block and outputs it to the resource role assignment unit 205, the MIMO demodulation unit 211, the rate de-matching unit 213, and the FEC decoder 215. do.

The layer ordering unit 207 determines a transport block to be decoded first of two transport blocks carrying a traffic channel signal. In general, the layer ordering unit 207 outputs an equivalent channel value output from the equivalent channel generator 209, a Log Likelihood Ratio (LLR) value output from the MIMO demodulator 211, or a CRC error detection unit 217. The channel state of each transport block is determined using an error detection result, and the decoding order is determined so that the channel state can be decoded from a good transport block. In this case, the equivalent channel generator 209 may be configured to determine the effect of the transmission signal being pre-coded into a large-delay CDD according to a rule determined according to the number of transport layers detected by the control channel detector 219 and resource allocation information of the traffic channel. Reflect on the value.

The MIMO demodulator 211 receives MIMO received signals of the equivalent channel value and the traffic channel of the equivalent channel generator 209 with respect to the transport block decoded first according to the decoding order determined by the layer ordering unit 207. The algorithm generates an LLR value and outputs the LLR value to the rate de-matching unit 213.

The rate de-matching unit 213 receives the signal output from the MIMO demodulation unit 211 and performs rate de-matching. The rate de-matching unit 213 performs FEC decoding through the FEC decoding unit 215 and then outputs it to the CRC error detection unit 217. The CRC error detection unit 217 detects an error generated in the transmission process through the CRC method from the decoded signal from the FEC decoder 215 and then determines whether to retransmit, and if the error is not detected, decodes the decoded signal. Pass it to the upper layer. The MIMO reception algorithm is mainly based on a linear reception algorithm based on MMSE (Minimum Mean Square Examination) or QR decomposition and an algorithm based on ML (Maximum Likelihood).

Meanwhile, the LLR value for the second decoded transport block according to the decoding order determined by the layer ordering unit 207 is determined by using the regeneration block 230 when a CRC error is not detected in the first decoded transport block. Can be generated. That is, a transmission signal for the first decoded transport block is generated and transmitted to the MIMO demodulation unit 211, and the MIMO demodulation unit 211 transmits the transmission signal for the first decoded transport block in the received signal of the traffic channel. By removing the LLR value for the second transport block, the LLR value is output to the rate de-matching unit 213. The rate de-matching unit 213 receives the signal output from the MIMO demodulation unit 211 and performs rate de-matching. The rate de-matching unit 213 performs FEC decoding through the FEC decoding unit 215 and then outputs it to the CRC error detection unit 217. The CRC error detection unit 217 detects an error generated in the transmission process through the CRC method from the decoded signal from the FEC decoder 215 and then determines whether to retransmit, and if the error is not detected, decodes the decoded signal. Pass it to the upper layer.

Herein, a case where a CRC error is not detected in the first decoded transport block has been described as an example. When a CRC error is not detected in the first decoded transport block, the traffic channel is used by using the regeneration block 230. A method of removing the transmission signal for the first decoded transport block from the received signal of is called an SIC method. If a CRC error is detected in the first decoded transport block, the LLR value of the second decoded transport block is also generated in the same manner as the first decoded transport block.

The CQI metric generator 221 generally estimates a CQI metric value such as an effective signal to interference plus noise ratio (SINR) using the equivalent channel value output from the equivalent channel generator 209. And outputs to the CQI generation unit 223. Herein, it is assumed that the CQI metric value is generated using the equivalent channel value. However, the CQI metric value may be generated using the LLR value output from the MIMO demodulator 211.

The CQI generator 223 receives the CQI metric value output by the CQI metric generator 221 and quantizes the CQI metric to generate a CQI index to be reported to the transmitter. In this case, the CQI generation unit 223 may use ACK (ACKnowledgement) / NACK (NACKnowledgement) information input from the CRC error detection unit 217 to generate the CQI index. The generated CQI index is included in the feedback information and fed back to the transmitter.

On the other hand, assuming that the signals output from the second and third modulators 127 and 129 of FIG. 1 are [x ₁ , x ₂ ] ^T , the traffic channel signals [y ₁ , y output through the precoding unit 131]. ₂ ] ^T may be represented by Equation 1 below.

In Equation 1, i represents indexes (0, 1, 2) of a resource element (RE) on which a traffic channel signal is transmitted.

In addition, the equivalent channel actually experienced by x ₁ and x ₂ in the receiver of FIG. 2 may be represented by Equation 2 below.

As can be seen from Equation 2, assuming that actual channel characteristics are the same between adjacent resource elements, since x ₁ and x ₂ experience equivalent channel characteristics, CQI feedback information transmitted to a transmitter to which a large delay CDD is applied. Does not transmit a separate value for each transport block, but delivers only one value. Therefore, the transmitter also determines the same value when determining the MCS level for each transport block.

However, when the MCS level of each transport block is the same in the transmitter to which the large delay CDD is applied as described above, there is a problem in that the potential throughput improvement capability of the SIC receiver is not exhibited.

The present invention proposes a transceiver for improving throughput in a MIMO communication system and a method of supporting the same.

In addition, the present invention proposes a transmission apparatus for selecting an MCS level so as to improve a throughput in a MIMO communication system and a method of supporting the same.

In addition, the present invention proposes a receiving apparatus for generating CQI information and a method for supporting the same to improve throughput in a MIMO communication system.

The present invention provides a method for transmitting at least two transport blocks in a MIMO (Multi Input Multi Output) communication system, wherein a type of a receiver that receives the at least two transport blocks removes continuous interference. (SIC: Successive Interference Cancelation) A process of determining whether a receiver and the transmitter, the modulation and coding scheme (MCS: Modulation and Coding Scheme for the at least two transport blocks depending on whether the type of the receiver is an SIC receiver) Determining a level) and transmitting the at least two transport blocks by applying the determined MCS level.

An apparatus for transmitting at least two transport blocks in a multi-input multiple output communication system provided by the present invention comprises: first means for determining whether a type of a receiver receiving the at least two transport blocks is a continuous interference cancellation receiver; An MCS selector for determining MCS levels for the at least two transport blocks according to whether the type of the receiver is an SIC receiver, and a signal generator for applying the determined MCS level to the at least two transport blocks and transmitting the same; .

In the multi-input multi-output communication system provided by the present invention, a method of receiving at least two transport blocks by a receiver from a transmitter includes: transmitting, by the receiver, type information indicating whether the receiver is a continuous interference cancellation receiver; Receiving, by the receiver, response information indicating reception of the receiver type information from the transmitter using an upper message; and receiving, by the receiver, channel quality information (CQI) in response to the response information; Transmitting to a transmitter; and receiving, by the receiver, the at least two transport blocks to which a modulation and coding scheme (MCS) determined using the channel quality information is applied.

In the multi-input multiple output communication system provided by the present invention, a receiver for receiving at least two transport blocks from a transmitter includes a type generator for generating and transmitting type information indicating whether the receiver is a continuous interference cancellation receiver, and the transmitter. Receiving response information indicating reception of the receiver type information from an upper layer message using a higher message, the CQI generation unit generating channel quality information corresponding to the response information and transmitting the same to the transmitter; And a signal receiver configured to receive the at least two transport blocks to which a modulation and coding scheme is applied.

The present invention can improve the potential throughput of the SIC receiver by adjusting the transmission and reception apparatus so that the optimal AMC can be performed according to each receiver in the MIMO communication system.

1 is a diagram illustrating a structure of a transmitter precoded with a large delay CDD in a MIMO communication system;
2 is a diagram illustrating a receiver structure corresponding to the transmitter of FIG. 1 and to which an SIC scheme is applied in a MIMO communication system; FIG.
3 is a graph comparing throughput of a receiver using an MML method and a receiver using an MML-SIC method as a MIMO reception algorithm;
4 is a diagram illustrating a first transmitter structure proposed by an embodiment of the present invention for improving throughput in a MIMO communication system.
5 is a flowchart illustrating operations of a receiver type estimator 401 and an MCS selector 403 of the first transmitter for improving throughput in a MIMO communication system according to a first embodiment of the present invention;
6 is a flowchart illustrating an operation of the MCS selector 403 of the first transmitter for improving throughput in a MIMO communication system according to a second embodiment of the present invention;
FIG. 7 illustrates a structure of a second transmitter for improving throughput in a MIMO communication system according to a third embodiment and a fourth embodiment of the present invention; FIG.
8 is a flowchart illustrating an operation of an MCS selector 703 of a second transmitter and an operation of a receiver corresponding to the second transmitter in a MIMO communication system;
9 is a flowchart illustrating an operation of an MCS selector 703 of a second transmitter and an operation of a receiver corresponding to the second transmitter in a MIMO communication system;
FIG. 10 is a diagram illustrating an SIC receiver structure according to third and fourth embodiments of the present invention for improving throughput in a MIMO communication system. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, only parts necessary for understanding the operation of the present invention will be described, and other background art will be omitted so as not to distract from the gist of the present invention.

In the present specification, an embodiment of a transmitting and receiving apparatus and method for improving throughput in a MIMO communication system will be described in detail.

In the present specification, an embodiment of a method of selecting a MCS level by a transmitting device for improving throughput in a MIMO communication system and a method of generating a CQI to be fed back to the transmitting device will be described in detail.

In the following description, embodiments of the present invention will be described as an example of an apparatus for transmitting and receiving in a MIMO communication system using an LTE standard that represents the latest version of a 3GPP (3rd Generation Partnership Project) series of communication networks. will be.

In addition, embodiments of the present invention can be applied to all precoding techniques for having the same equivalent channel for each transport block, such as the large delay CDD of the LTE standard, and in the following description of embodiments of the present invention, LTE It assumes and explains the large delay CDD.

3 is a graph comparing throughput of a receiver using an MML (Modified Maximum Likelihood) method and a receiver using an MML-SIC method as a MIMO reception algorithm.

As shown, it can be seen that the throughput is also increased in proportion to the increase in the signal to noise ratio (SNR), and the throughput of the MML-SIC receiver is higher than that of the MML receiver. In order to obtain an improved throughput like the MML-SIC receiver, the transmitter must allocate different MCS levels for each transport block according to the characteristics of the MML-SIC receiver.

4 is a diagram illustrating a structure of a first transmitter for improving throughput in a MIMO communication system.

Referring to FIG. 4, the first transmitter includes a receiver type estimator 401, an MCS selector 403, a first CRC error detector 405, a first FEC coder 407, and a first modulator. 409, resource allocation unit 411, first IFFT unit 413, serial / parallel conversion unit 415, second CRC error detection unit 417, third CRC error detection unit 419, second FEC code Unit 421, third FEC coder 423, first rate matcher 425, second rate matcher 427, second modulator 429, third modulator 431, precoding A portion 433 and a second IFFT portion 435 are included. Here, the serial / parallel converter 415, the second CRC error detector 417, the third CRC error detector 419, the FEC coder 420, the rate matcher 424, and the modulator 428 generate signals. It can be collectively called negative.

The first transmitter has almost the same configuration except for the transmitter, the receiver type estimator 401 and the MCS selector 403 of FIG. 1, and the receiver type estimator 402 operates as shown in FIG. 5. It is determined whether the reception algorithm of each receiver is based on the SIC, and the result is transmitted to the MCS selector 403.

5 is a flowchart illustrating operations of the receiver type estimator 401 and the MCS selector 403 of the first transmitter for improving throughput in a MIMO communication system according to the first embodiment of the present invention.

Referring to FIG. 5, in step 501, the receiver type estimator 401 measures a throughput of a receiver when the same MCS level is allocated to each transport block during K ₁ subframes, and transmits each transmission during K ₂ subframes in step 503. The receiver measures the throughput when different MCS levels are assigned to a block. Here, each transport block corresponds to each transport layer, and K ₁ and K ₂ The subframe means a predetermined time period.

To this end, the MCS selector 403 allocates the same MCS level to each transport block (i.e., each transport layer) during the K ₁ subframe, and different to each transport block (i.e., each transport layer) during the K ₂ subframe. Assign the MCS level. In order to allocate different MCS levels to each transport block, the MCS selector 403 uses, for example, an MCS offset table given for each user (or for each transport block), or uses ACK / NACK information transmitted from a receiver. To adjust the MCS level. As another example, the MCS level adjustment using the ACK / NACK information and the MCS offset table may be performed together. The MCS offset table includes offset values of other transport blocks with respect to MCS level values of one transport block.

Then, in step 505 the receiver type estimator 401 is the K ₁ and K ₂ Compare the average throughput during the subframe, K ₂ If the average throughput during the subframe is high, the process proceeds to step 507 and determines that the receiver is an SIC receiver. But said K ₁ If the average throughput is high during the subframe, the process proceeds to step 511 and determines that the corresponding receiver is not an SIC receiver. In this way, the receiver type estimator 401 determines the type of the corresponding receiver through steps 501 to 509 and outputs the result to the MCS selector 403.

The MCS selector 403 according to the type of the receiver input from the receiver type estimator 401, if the receiver is an SIC receiver, proceeds to step 509 and uses a MCS offset table given to each user, and thus different MCSs for each transport block. If the level is allocated and the corresponding receiver is not the SIC receiver, the process proceeds to step 513 to allocate the same MCS level to each transport block.

For example, the same number of bits may be used to represent MCS levels for two transport blocks. However, in general, since the difference between the MCS level values of the two transport blocks is small compared to the range of the total MCS level values, it is possible to reduce the number of bits of the control signal used when differentially encoding and transmitting each MCS level index. In this case, if the reduced number of bits is used only for HARQ (hybrid automatic repeat reQuest), the differential encoding should be performed to be sufficient to represent the modulation order used in retransmission.

So far, the first embodiment of the case in which the receiver type estimator 401 determines the receiver type and transmits the receiver type to the MCS selector has been described, and the operation of the MCS selector 403 according to the determined receiver type is fixed for a certain time thereafter. In this case, the operation of FIG. 5 may be repeatedly performed.

In the first embodiment, the first transmitter assigns a different MCS level to the transport block if the type of the receiver is an SIC receiver, and assigns the same MCS level to the transport block if the type of the receiver is not an SIC receiver.

Meanwhile, the second embodiment describes a method of increasing the time interval allocated to different MCS levels if it is determined that the receiver is an SIC receiver and increasing the time interval allocated to the same MCS level if it is determined that the receiver is not an SIC receiver. That is, in the second embodiment, the throughput of the receiver may be increased by adaptively adjusting the length of the section allocating the same MCS level and the section allocating a different MCS level. In this case, the receiver type estimator 401 does not transmit the determined receiver type to the MCS selector 403, and the MCS selector 403 directly adjusts the length of each section to allocate an MCS level.

6 is a flowchart illustrating an operation of an MCS selector 403 of a first transmitter for improving throughput in a MIMO communication system according to a second embodiment of the present invention.

Referring to FIG. 6, the MCS selector 403 allocates the same MCS level to the transport block during the K ₁ subframe in step 601, and assigns a different MCS level to the transport block during the K ₂ subframe in step 603. Then in step 605 K ₁ and K ₂ Comparing the average throughput for the receiver during subframes, K ₁ is higher average throughput for the sub-frame goes to step 607 to proceed to the next step 601 is increased by an amount determined by the ratio of K ₁ sub-frame advance, K ₂ sub If the average throughput during the frame is high, the process proceeds to step 609 to increase the ratio of the K ₂ subframes by a predetermined amount and then proceeds to step 601. Although not shown, when the average throughput during the K ₁ subframe and the average throughput during the K ₂ subframe are the same, the process may proceed to step 607 or 609 according to the system design, or maintain the current ratio of each subframe. .

As described above, the MCS selector 403 uses the fixed K ₁ and K ₂ determined by the receiver type estimator 401 as described in the first embodiment of FIG. 5. Using the receiver type is assigned to the same or different MCS level in each transmission block or, or an MCS selecting section 403, as described in the second embodiment of Figure 6 in accordance with the average throughput for the sub-frame is K ₁ and K ₂ The same or different MCS level may be allocated to each transport block while adjusting the ratio of subframes.

The first and second embodiments according to the first transmitter of FIG. 4 described above are embodiments in which the first transmitter determines itself the type of the receiver. That is, the first transmitter measures receiver throughput during the first time period in which the MCS level is set equal to the second time period in which the MCS level is set differently, compares the measured throughputs, and sets the type of receiver according to the result. An embodiment (first embodiment) that determines and determines an MCS level equally or differently according to the type of the determined receiver, and an embodiment that increases a time period to which the same or different MCS level is applied (second embodiment). It was.

Hereinafter, a third embodiment and a fourth embodiment according to the second transmitter of FIG. 7 will be described. The third and fourth embodiments are embodiments in which a transmitter receives information indicating the type of the receiver from the receiver to recognize the type of the receiver. It will be described in detail below.

7 illustrates a structure of a second transmitter for improving throughput in a MIMO communication system according to a third embodiment and a fourth embodiment of the present invention.

Referring to FIG. 7, the second transmitter includes an MCS selector 703, a first CRC error detector 705, a first FEC coder 707, a first modulator 709, a resource allocator 711, A first IFFT unit 713, a serial / parallel conversion unit 715, a second CRC error detector 717, a third CRC error detector 719, a second FEC coder 721, a third FEC coder ( 723, a first rate matcher 725, a second rate matcher 727, a second modulator 729, a third modulator 731, a precoding unit 733, and a second IFFT unit 735 ).

The second transmitter has the same configuration as that of the transmitter of FIG. 1 and merely provides the MSC selector 703 with the receiver type information 701 transmitted from the receiver using the spare bits of the upper message. This is distinguished from the transmitter of FIG. Here, as an example of a method of transmitting the receiver type information 701 through an upper message, the receiver type information 701 may be performed using extra bits between the transceivers.

8 is a flowchart illustrating an operation of an MCS selector 703 of a second transmitter and an operation of a receiver corresponding to the second transmitter in a MIMO communication system.

Referring to FIG. 8, the MCS selector 703 of the second transmitter receives the receiver type information 701 from the receiver through an uplink upper message in step 801 and proceeds to step 803. Thereafter, the second transmitter transmits response information indicating whether the receiver type information 701 has been successfully received to the receiver. In operation 809, the receiver corresponding to the second transmitter receives the response information transmitted by the second transmitter through a downlink upper message and proceeds to operation 811.

In step 803, the MCS selector 703 determines whether the receiver is an SIC receiver based on the received receiver type information 701.

As a result of the determination, when the receiver is an SIC receiver, the process proceeds to step 805 and differently determines the MCS level of each transport block using the CQI feedback information 700. In this case, the MCS level of each transport block may be determined using CQI feedback information individually fed back from the receiver for each transport block.

As a result of the determination, if the receiver is not the SIC receiver, the process proceeds to step 807 and uses the CQI feedback information 700 to determine the MCS level of each transport block in the same manner. In this case, the MCS level of each transport block may be determined using CQI feedback information fed back from the receiver for a predetermined transport block.

Meanwhile, in step 811, if the receiver is an SIC receiver, the receiver proceeds to step 813 and alternately feeds back the CQI of the first decoded transport block and the CQI of the second decoded transport block to the second transmitter. It allows the transmitter to determine the MCS level of each transport block differently.

If the receiver is not an SIC receiver in step 811, the process proceeds to step 815 to feed back CQI information for one predetermined transport block to a second transmitter, so that the second transmitter equals the MCS level of each transport block. Make a decision. 9 is a flowchart illustrating an operation of an MCS selector 703 of a second transmitter and an operation of a receiver corresponding to the second transmitter in a MIMO communication system.

9, the MCS selector 703 of the second transmitter receives the receiver type information 701 through the uplink higher message in step 901 and proceeds to step 903.

In step 903, the MCS selector 703 determines whether the receiver is an SIC receiver based on the received receiver type information 701.

As a result of the determination, when the receiver is an SIC receiver, the process proceeds to step 905 to differently determine the MCS level of each transport block using at least one of the CQI feedback information 700 and the MCS offset table for each transport block.

Specifically, the MCS level is determined using only the CQI feedback information 700 for the initial transport block, and the MCS level is determined using the CQI feedback information 700 and the MCS offset table for the retransmission block.

As a result of the determination, when the receiver is not the SIC receiver, the process proceeds to step 907 to determine the MCS level of each transport block equally using the CQI feedback information 700.

Meanwhile, in step 909, the receiver corresponding to the second transmitter feeds back CQI information for one predetermined transport block regardless of whether the receiver corresponds to the SIC receiver.

FIG. 10 is a diagram illustrating an SIC receiver structure according to third and fourth embodiments of the present invention for improving throughput in a MIMO communication system.

Referring to FIG. 10, the SIC receiver includes a first FFT unit 1001, a second FFT unit 1003, a resource role assignment unit 1005, a layer ordering unit 1007, an equivalent channel generation unit 1009, and MIMO recovery. Grandfather 1011, rate de-matching unit 1013, FEC decoder 1015, CRC error detector 1017, CQI generator 1023, CQI metric generator 1021, FEC coder 1031, rate The matching unit 1033 and the modulator 1035 are included.

The SIC receiver has the same configuration as that of the receiver of FIG. 2, and the signal input to the layer ordering unit 1007 and the operation of the layer ordering unit 1007 are distinguished from the receiver of FIG. 2. In addition, although not shown, the SIC receiver includes a type information generator for generating type information indicating that its receiver type is an SIC receiver, and the type information is transmitted to the transmitter.

The layer ordering unit 1007 does not determine the decoding order of the transport block according to the channel state, and decodes the transport block having the lowest MCS level by using the MCS level for each transport block of each user input from the control channel detector 1019. Determine the decoding order so that it can be done. That is, the first decoding of the transport block having the lowest MCS level, the first decoding of the transport block of the low MCS level of the transport block of the equivalent channel lowers the error rate of the first decoded transport block. Therefore, since the probability of removing the transmission signal for the first transport block from the received signal increases, as a result, the gain of the SIC receiver increases.

Meanwhile, the decoding order according to whether a transport block is an initial transport block or a retransmission block is as follows.

In the first case, if the transport blocks are all initial transport blocks, the transport blocks are decoded according to the lowest MCS level of each transport block. This is because the error rate of the first decoded transport block is lowered when decoding the transport block having the lower MCS level among the transport blocks of the equivalent channel first, thus increasing the probability of removing the transmission signal for the first decoded transport block from the received signal. This increases the gain of the SIC receiver.

In the second case, if the transport blocks are all retransmission blocks, the retransmission blocks are decoded according to the order of decreasing MCS level of the initial transport block for each of the retransmission blocks.

In a third case, if a transport block includes an initial transport block and a retransmission block, the initial transport block is decoded before the retransmission block. In this case, if there are a plurality of initial transport blocks, as in the first case, the MCS level is decoded in descending order, and if there are a plurality of retransmission blocks, each initial transport block for the retransmission block as in the second case. The MCS level is decoded in descending order.

On the other hand, when the CQI feedback information is reported only for one transport block in a transceiver to which a large-delay CDD is applied as in the prior art, there is a limitation in the utilization of the SIC receiver. If it is possible to report the CQI feedback information for each of the two transport blocks as described in FIG. 8, the CQI metric generator 1021 of FIG. 10 first generates the CQI of the transport block to be decoded in the same manner as in the conventional scheme. However, the second CQI of the transport block to be decoded must be generated using Equations 3 and 4 below. Since each transport block has equivalent channel characteristics, Equations 3 and 4 have the same value.

If it is possible to feed back the CQI for each of the transport blocks having equivalent channel characteristics as shown in Equation 3 and Equation 4, the transmitter does not use the MCS offset table and uses only the CQI feedback information to transmit the CQI. It is possible to determine the MCS level. In particular, when the number of bits used for reporting the CQI feedback information is set to the same as in the related art, the CQI feedback information for each transport block may be reported alternately only when the receiver type is an SIC receiver.

Claims

A method for transmitting at least two transport blocks in a multi-input multi-output (MIMO) communication system,
Determining, by the transmitter, whether the type of the receiver receiving the at least two transport blocks is a successive interference cancellation (SIC) receiver;
Determining, by the transmitter, a modulation and coding scheme (MCS) level for the at least two transport blocks according to whether the type of the receiver is an SIC receiver;
And transmitting the at least two transport blocks by applying the determined MCS level.

The method of claim 1, wherein the determining of the SIC receiver comprises:
And measuring and determining a throughput of the receiver.

The method of claim 1, wherein the determining of the SIC receiver comprises:
Applying the same MCS level to the at least two transport blocks during a first time period, and measuring a first throughput of the receiver during the first time period;
Applying a different MCS level to the at least two transport blocks during a second time period and measuring a second throughput of the receiver during the second time period;
Determining the type of the receiver as an SIC receiver when the second throughput is greater than the first throughput;
Determining that the type of the receiver is not an SIC receiver if the first throughput is greater than the second throughput.

The method of claim 1, wherein the determining of the MCS level for the transport block comprises:
If the type of the receiver is an SIC receiver, differently determining MCS levels for the at least two transport blocks;
If the type of the receiver is not an SIC receiver, determining the MCS level for the at least two transport blocks equally.

The method of claim 4, wherein determining the MCS level differently comprises:
MCS level using at least one of an MCS offset table for each transport block including an offset value of another transport block to an MCS level value of one transport block and ACK (ACKnowledgement) / NACK (NACKnowledgement) information transmitted from the receiver. Characterized in that it is determined differently.

The method of claim 3, wherein the determining of the MCS level for the transport block comprises:
Determining the MCS level by increasing the ratio of the second time interval when the second throughput is greater than the first throughput;
If the first throughput is greater than the second throughput, increasing the ratio of the first time period to determine an MCS level.

The method of claim 1, wherein the determining of the SIC receiver comprises:
Receiving type information indicating whether the receiver is an SIC receiver from the receiver;
And determining whether the receiver is an SIC receiver according to the received type information.

The method of claim 7, wherein
Transmitting response information informing of reception of the receiver type information to the receiver using an upper message;
And receiving channel quality information (CQI) from the receiver in response to the response information.

The method of claim 8, wherein the receiving of the CQI comprises:
Receiving CQIs for the at least two transport blocks separately if the type of the receiver is an SIC receiver;
If the type of the receiver is not an SIC receiver, receiving a CQI for a predetermined transport block.

The method of claim 9, wherein the determining of the MCS level for the transport block comprises:
If the type of the receiver is an SIC receiver, differently determining MCS levels for the at least two transport blocks according to individually received CQIs;
If the type of the receiver is not an SIC receiver, determining the MCS level for the at least two transport blocks equally according to the CQI for the predetermined one transport block.

The method of claim 8, wherein the receiving of the CQI comprises:
A method for transmitting a transport block, characterized in that receiving a CQI for one predetermined transport block.

The method of claim 11, wherein the determining of the MCS level for the transport block comprises:
If the type of the receiver is an SIC receiver, differently determining MCS levels for the at least two transport blocks using at least one of a CQI for the predetermined one transport block and an MCS offset table for each transport block;
If the type of the receiver is not an SIC receiver, determining the MCS level for the at least two transport blocks equally according to the CQI for the predetermined one transport block.

An apparatus for transmitting at least two transport blocks in a multi-input multi-output (MIMO) communication system,
First means for determining whether a type of a receiver receiving the at least two transport blocks is a successive interference cancellation (SIC) receiver;
An MCS selector for determining MCS levels for the at least two transport blocks according to whether the type of the receiver is an SIC receiver;
And a signal generator for applying the determined MCS level to the at least two transport blocks.

The method of claim 13, wherein the first means,
And measuring the throughput of the receiver to determine whether the receiver is the SIC receiver.

The method of claim 13, wherein the first means,
Applying the same MCS level to the at least two transport blocks during a first time period to measure the first throughput of the receiver during the first time period and different MCS levels to the at least two transport blocks during the second time period. Measure a second throughput of the receiver during the second time period, and if the second throughput is greater than the first throughput, determine the type of the receiver as an SIC receiver, and the first throughput is the second throughput. And a receiver type estimator for determining that the type of the receiver is not an SIC receiver.

The method of claim 13, wherein the MCS selector,
If the type of the receiver is an SIC receiver, the MCS levels for the at least two transport blocks are differently determined. If the type of the receiver is not an SIC receiver, the MCS levels for the at least two transport blocks are determined to be the same. A device for transmitting a transport block.

The method of claim 16, wherein the MCS selector,
MCS level using at least one of an MCS offset table for each transport block including an offset value of another transport block to an MCS level value of one transport block and ACK (ACKnowledgement) / NACK (NACKnowledgement) information transmitted from the receiver. Apparatus for transmitting a transport block, characterized in that differently determined.

The method of claim 15, wherein the MCS selector,
If the second throughput is greater than the first throughput, the MCS level is determined by increasing the ratio of the second time interval. If the first throughput is greater than the second throughput, the MCS level is determined by increasing the ratio of the first time interval. Apparatus for transmitting a transport block, characterized in that.

The method of claim 13, wherein the first means,
And a MCS selector for receiving type information indicating whether the receiver is an SIC receiver from the receiver.

The method of claim 19, wherein the MCS selector,
A transport block for transmitting the response information indicating the reception of the receiver type information to the receiver by using an upper message, and receiving channel quality information (CQI) from the receiver in response to the response information; Transmitting device.

The method of claim 20, wherein the MCS selector,
If the type of the receiver is an SIC receiver, the CQI for each transport block is individually received, and if the type of the receiver is not an SIC receiver, the CQI for a predetermined transport block is transmitted. Device.

The method of claim 21, wherein the MCS selector,
If the type of the receiver is an SIC receiver, the MCS level for the at least two transport blocks is differently determined according to the individually received CQIs, and if the type of the receiver is not an SIC receiver, And determining the MCS level for the at least two transport blocks in accordance with the CQI.

The method of claim 20, wherein the MCS selector,
And a CQI for one predetermined transport block.

The method of claim 23, wherein the MCS selector,
If the type of the receiver is an SIC receiver, MCS levels for the at least two transport blocks are differently determined using at least one of the CQI for the predetermined one transport block and the MCS offset table for each transport block, And if the type is not an SIC receiver, determine the MCS level for the at least two transport blocks equally according to the CQI for the predetermined one transport block.

In the multi-input multi-output (MIMO) communication system, the receiver receives at least two transport blocks from the transmitter,
Transmitting, by the receiver, type information indicating whether the receiver is a successive interference cancellation (SIC) receiver;
Receiving, by the receiver, response information indicating the reception of the receiver type information from the transmitter using a higher message;
Transmitting, by the receiver, channel quality information (CQI) to the transmitter in response to the response information;
And receiving, by the receiver, the at least two transport blocks to which a modulation and coding scheme (MCS) determined using the channel quality information is applied.

The method of claim 25, wherein the transmitting of the CQI,
If the type of the receiver is an SIC receiver, separately transmitting the CQIs for the at least two transport blocks in the order in which the at least two transport blocks are decoded;
If the type of the receiver is not an SIC receiver, transmitting a CQI for one predetermined transport block.

The method of claim 25, wherein the receiving of the at least two transport blocks comprises:
And receiving and decoding the transmission block in the order of transport blocks having a lower MCS level among the at least two transport blocks.

The method of claim 25, wherein the receiving of the at least two transport blocks comprises:
If at least one of the at least two transport blocks is a retransmitted transport block, first decoding a transport block initially transmitted;
If the at least two transport blocks are all retransmitted transport blocks, decoding the MCS levels of the initial transport blocks for the retransmitted transport blocks in descending order.

A receiver for receiving at least two transport blocks from a transmitter in a multi-input multi-output (MIMO) communication system,
A type generator for generating and transmitting type information indicating whether the receiver is a successive interference cancellation (SIC) receiver;
A CQI generation unit for generating channel quality information (CQI) in response to the response information and transmitting the response information indicating the reception of the receiver type information from the transmitter using an upper message; ,
And a signal receiving unit configured to receive the at least two transport blocks to which a modulation and coding scheme (MCS) determined using the channel quality information is applied.

The method of claim 29, wherein the CQI generation unit,
If the type of the receiver is an SIC receiver, the CQI for each of the transport blocks is transmitted separately, and if the type of the receiver is not an SIC receiver, the transport block is characterized in that the transmission of the CQI for one predetermined transport block Receiver.

The method of claim 29, wherein the signal receiving unit,
And a layer ordering unit configured to determine a decoding order of the at least two transport blocks in order of transport blocks having a lower MCS level.

The method of claim 25, wherein the signal receiving unit,
If at least one of the at least two transport blocks is a retransmitted transport block, the first transport block is decoded first. If the at least two transport blocks are both retransmitted transport blocks, an MCS of an initial transport block for the retransmitted transport block. A receiver for receiving a transport block including a layer ordering unit for determining the decoding order to decode in order of the lowest level.