KR100438564B1 - Adaptive modulation coding apparatus for mobile communication device - Google Patents

Abstract

The present invention relates to an adaptive modulation coding apparatus of a mobile communication terminal which improves error performance and transmission rate of a forward link by combining an AMC with a BLAST having an independent layer structure for each transmission antenna. An encoder; A channel interleaver for interleaving data output from the encoder; A modulator for modulating data output from the channel interleaver; A transmission antenna selection unit for selecting a transmission antenna for outputting the modulated data based on a channel / SNR estimation value which is feedback information; A BLAST processing unit which sequentially receives data output from the modulator and outputs the data through the selected transmission antenna; A BLAST decoder for BLAST decoding the data received through the antenna; A channel / SNR estimator for receiving the BLAST decoded data and estimating channel state information; An MCS level selector for applying a control signal for selecting an optimal scheme and coding type within an MCS threshold to an encoder, a channel interleaver, and a modulator based on the channel / SNR estimate output from the channel / SNR estimator; A demodulator for demodulating the decoded data output from the BLAST decoder by the channel estimate value; A channel deinterleaver for channel deinterleaving demodulation data output from the demodulator; And a decoder for decoding the data output from the channel deinterleaver and outputting information bits.

Description

ADAPTIVE MODULATION CODING APPARATUS FOR MOBILE COMMUNICATION DEVICE

The present invention relates to a method for increasing a forward link transmission rate of a mobile communication terminal. In particular, an independent layer structure for each STD and a transmission antenna, which is a closed-loop technique, is used for adaptive modulation coding (AMC). The present invention relates to an adaptive modulation coding apparatus of a mobile communication terminal which improves error performance and transmission rate of a forward link by combining BLAST (Bell-Lab Layered Space-Time).

In general, Adaptive Modulation Coding (AMC) has a configuration as shown in FIG. 1 and feeds back the channel estimation value of a receiver to a transmitter to transmit in an optimal modulation and coding form.

That is, the transmission data is encoded through the encoder 1, interleaved through the channel interleaver 2, modulated by the modulator 3, and then transmitted and output.

Next, the data received from the counterpart through the antenna ANT is demodulated by the demodulator 4 and the signal estimator SNR is detected by the channel estimator 5.

Accordingly, the demodulated data is deinterleaved through the channel deinterleaver 7, decoded and output through the decoder 8, and modulated / coded selector 6 by the channel estimate detected by the channel estimator 5. ) Controls the sender component with the optimal modulation and coding scheme.

At this time, the modulation coding selector (MCS: Modulation Coding Scheme 6), as shown in Figure 2 allows to achieve the optimal transmission rate in consideration of four cases.

However, the AMC has a problem that the rate performance is improved but the error performance is not improved by simply changing the modulation and coding scheme according to channel conditions.

BLAST, a system structure technique, is classified into two types, D (Diagonal) -BLAST and V (Vertical) -BLAST.

In both of the above schemes, modulation and coding are performed by parallelizing transmission data sequentially input by the number of transmission antennas. As data is continuously input, bit strings, that is, layers, are formed as many as the number of transmission antennas.

As shown in FIG. 3, the structure of the transmitter of the mobile communication terminal to which the D-BLAST is applied is configured such that data output from one specific layer is periodically transmitted through another antenna. Diagonal transmission on the view.

However, the method of applying the D-BLAST has a problem of improving the error performance but not improving the transmission rate.

The structure of the transmitting terminal of the mobile communication terminal applying the V-BLAST, as shown in Figure 4, is configured to transmit the data of each layer to its own transmission antenna, and has a vertical form on the space, time axis, such V The method of applying -BLAST also has the problem of improving the error performance but not improving the transmission rate.

For reference, FIG. 5 is an exemplary view illustrating channel characteristics using a MIMO multiplexing technique. When multiple antennas are used for a transmitting and receiving end, if the different data is transmitted for each transmitting antenna using the MIMO multiplexing technique, the peak throughput of the system (Peak) throughput can be increased.

Next, STD (Selection Transmit Diversity), which is a closed-loop technique, returns a channel condition at the receiver as shown in FIG. 6, and feeds information to the transmitter, thereby providing an antenna corresponding to an optimal channel condition. In this case, only the best transmission antenna is selected, unlike the STTD, which is averaging as shown in FIG. 7, and thus the receiver receives the optimal data. As shown in FIG. 7, the STTD (Space-Time Transmit Diversity) You have a better SNR.

However, the diversity scheme, STD, has an improvement effect on the error performance, but has a problem in that the transmission rate is not improved.

Accordingly, the present invention has been created to solve the above-described problems, and has an independent layer structure for each transmission antenna (STD) and a transmission antenna, which is a closed-loop technique in adaptive modulation coding (AMC). It is an object of the present invention to provide an adaptive modulation coding apparatus of a mobile communication terminal to improve error performance and transmission rate of a forward link by combining BLAST (Bell-Lab Layered Space-Time).

The present invention for achieving the above object is an encoder for encoding the transmission data; A channel interleaver for interleaving data output from the encoder; A modulator for modulating data output from the channel interleaver; A transmission antenna selection unit for selecting a transmission antenna for outputting the modulated data based on a channel / SNR estimation value which is feedback information; A BLAST processing unit which sequentially receives data output from the modulator and outputs the data through the selected transmission antenna; A BLAST decoder for BLAST decoding the data received through the antenna; A channel / SNR estimator for receiving the BLAST decoded data and estimating channel state information; An MCS level selector for applying a control signal for selecting an optimal scheme and coding type within an MCS threshold to an encoder, a channel interleaver, and a modulator based on the channel / SNR estimate output from the channel / SNR estimator; A demodulator for demodulating the decoded data output from the BLAST decoder by the channel estimate value; A channel deinterleaver for channel deinterleaving demodulation data output from the demodulator; And a decoder for decoding the data output from the channel deinterleaver and outputting information bits.

1 is a block diagram showing the configuration of a conventional AMC (Adaptive Modulation Coding).

2 is an exemplary diagram for explaining a selection condition of an MCS selector in the AMC of FIG.

3 is a schematic diagram showing the structure of a transmitting end of a conventional D-BLAST;

4 is a schematic diagram showing the structure of a transmitting end of a conventional V-BLAST;

5 is an exemplary diagram illustrating channel characteristics using a MIMO multiplexing technique.

6 is an exemplary view for explaining the basic operation of the conventional STD.

7 is a state diagram showing the SNR by the STD of FIG.

8 is an exemplary view showing the performance when the AMC and BLAST is integrated in accordance with the present invention.

9 is a block diagram showing a configuration incorporating the closed loop scheme STD in the AMC in accordance with the present invention.

10 is a block diagram showing the configuration of a device combining BLAST and STD in accordance with the present invention.

11 is a block diagram showing the configuration of a device combining AMC, STD and BLAST in accordance with the present invention.

FIG. 12 is an exemplary diagram illustrating a frame error rate (FER) and throughput in a conventional AMC technique. FIG.

13 is an exemplary view showing an error performance according to the conventional diversity (Diversity).

14 is an exemplary view showing error performance according to a conventional BLAST when two transmission antennas are used.

15 is an exemplary view showing error performance according to a conventional BLAST when four transmission antennas.

16 is an exemplary view showing the performance when the AMC and diversity (STTD, STD) is integrated in accordance with the present invention.

Figure 17 is a state diagram showing the performance when the AMC and BLAST integrated in accordance with the present invention.

18 is a state diagram comparing the performance when AMC and BLAST and AMC and STD are integrated.

19 is a state diagram showing the performance when the BLAST and STD are integrated in accordance with the present invention.

20 is a state diagram showing the performance when the AMC, STD and BLAST are integrated in accordance with the present invention.

*** Explanation of symbols for the main parts of the drawing ***

301,401 Encoder 302,402 Channel Interleaver

303,403: modulator 304,404: transmit antenna selector

305,405: BLAST processing unit 306,406: BLAST decoder

307,407 Channel / SNR Estimator 308,408 Demodulator

309,409 Channel Deinterleaver 310410 Decoder

411: MCS level selector

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described. Many specific details, such as specific processing flows, are set forth in the following description in order to provide a more general understanding of the invention, and it is to be understood by those skilled in the art that the present invention may be practiced without these specific details. Will be self explanatory. In addition, detailed description of well-known functions and structures which are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

FIG. 8 is a block diagram showing the configuration of a device incorporating BLAST in the AMC of the present invention, and feedback information informs all antennas or AMC modulation and coding level selection information of each antenna, and a transmitting end according to this information. For every transmit antenna or each transmit antenna, determine the optimal modulation scheme and coding type within the MCS threshold.

That is, the combined device integrating AMC and BLAST comprises: an encoder 101 for encoding transmission data; A channel interleaver (102) for interleaving data output from the encoder (101); A modulator (103) for modulating data output from the channel interleaver (102); A BLAST processing unit 104 for sequentially receiving data output from the modulator 103 and outputting the data in parallel by the number of transmitting antennas; A BLAST decoder 105 for BLAST decoding the data received via the antenna; A channel estimator (106) for receiving the BLAST decoded data and estimating channel state information; The channel estimation value output from the channel estimator 106 applies a control signal to the encoder 101, the channel interleaver 102, and the modulator 103 for selecting an optimal scheme and coding type within the MCS threshold. An MCS level selector 110; A demodulator (107) for demodulating the decoded data output from the BLAST decoder (105) by the channel estimate value; A channel deinterleaver (108) for channel deinterleaving demodulation data output from the demodulator (107); The decoder 109 decodes the data output from the channel deinterleaver 108 and outputs information bits. The operation of the apparatus configured as described above will be described below.

First, the BLAST decoder 105 performs BLAST decoding on data received through an antenna and applies it to the channel estimator 106 and the demodulator 107, and the channel estimator 106 is output from the BLAST decoder 105. The channel state information is estimated by applying the received data to the demodulator 107 and the MCS level selector 110.

Accordingly, the MCS level selector 110, based on the channel estimation value output from the channel estimator 106, the control signal for selecting the optimal method and coding type within the MCS threshold, encoder 101, channel The interleaver 102 and the modulator 103.

Accordingly, the encoder 101, the channel interleaver 102, and the modulator 103 process data in an optimal manner and coding form within an MCS threshold selected by a control signal of the MCS level selector 110. That is, the encoder 101 encodes the transmission data and interleaves it through the channel interleaver 102, and then modulates and outputs the data output from the channel interleaver 102 in the modulator 103.

Thereafter, the BLAST processing unit 104 sequentially receives data output from the modulator 103 and outputs the data in parallel by the number of transmitting antennas.

FIG. 9 is a block diagram showing a conventional AMC incorporating a closed loop scheme, STD, which is interleaved with the turbo encoder 202 encoding the transmission information bits 201 and the encoded information bits as shown. A channel interleaver (203), a symbol converter (204) for transforming the interleaved information by constellation mapping, and a Walsh modulator (205) for Walsh modulation of the symbol data. And a scrambler 206 that scrambles the Walsh modulated data, an antenna selector 207 that selects an antenna corresponding to an optimal channel condition, and outputs the scrambled data, and an antenna Rx. A channel compensator 208 for compensating for the channel of the symbol data received through the channel, a descrambler 211 for descrambled the channel compensated data, and a Walsh demodulator for the descrambled data. A demodulator 212, a bit converter 213 for converting the Walsh demodulated symbol data into information bits, a channel deinterleaver 214 for deinterleaving the converted information bits, and decoding the deinterleaved data. A map decoder 215 for outputting the information bits 216, a channel information detector 209 for detecting antenna selection and channel state information from the channel-compensated symbol data, and an encoder 202 by the channel information. The MCS selector 210 controls the channel interleaver 203 and the symbol converter 204 to optimally modulate and code information bits.

That is, in the configuration in which STD, which is a closed loop scheme, is integrated into the AMC as described above, the feedback information informs the antenna selection information as well as the AMC modulation and coding level selection, and the transmitting end selects a transmission antenna according to this information. Determine the optimal modulation scheme and coding type within the MCS threshold.

Fig. 10 is a block diagram showing the configuration of an apparatus combining BLAST and STD according to the present invention, and includes an encoder 301 for encoding transmission data as shown therein; A channel interleaver (302) for interleaving data output from the encoder (301); A modulator (303) for modulating data output from the channel interleaver (302); A transmission antenna selection unit 304 for selecting a transmission antenna for outputting data output from the modulator 303; A BLAST processing unit 305 which receives the output data sequentially and outputs the data through the selected antenna; A BLAST decoder 306 for BLAST decoding the data received via the antenna; A channel / SNR estimator 307 for receiving the BLAST decoded data and estimating channel state information and outputting the channel state information to a transmit antenna selector 304 and a demodulator 308; A demodulator (308) for demodulating the decoded data output from the BLAST decoder (306) by the channel / SNR estimate value; A channel deinterleaver (309) for channel deinterleaving demodulation data output from the demodulator (308); The decoder 310 decodes the data output from the channel deinterleaver 309 and outputs information bits. The operation of the apparatus configured as described above will be described below.

First, the BLAST decoder 306 BLAST decodes the data received through the antenna and applies it to the channel / SNR estimator 307 and the demodulator 308, and the channel / SNR estimator 307 receives the channel / SNR estimate. Is applied to the transmit antenna selector 304 so that the transmit antenna can be selected according to the optimal channel conditions.

The demodulator 308 then demodulates the decoded data output from the BLAST decoder 306 by the channel / SNR estimate, and the channel deinterleaver 309 deinterleaves the demodulated data output from the demodulator 308. The decoder 310 decodes the deinterleaved data and outputs an information bit.

Next, Fig. 11 is a block diagram showing the configuration of an apparatus combining AMC, STD, and BLAST according to the present invention, comprising: an encoder 401 for encoding transmission data as shown therein; A channel interleaver (402) for interleaving data output from the encoder (401); A modulator (403) for modulating data output from the channel interleaver (402); A transmission antenna selection unit 304 for selecting a transmission antenna for outputting the modulated data based on the channel / SNR estimation value which is feedback information; A BLAST processing unit 405 which sequentially receives data output from the modulator 403 and outputs the data through the selected transmission antenna; A BLAST decoder 406 for BLAST decoding the data received via the antenna; A channel / SNR estimator (407) for receiving the BLAST decoded data and estimating channel state information; Based on the channel / SNR estimation value output from the channel / SNR estimator 407, a control signal for selecting an optimal scheme and coding type within an MCS threshold is obtained by the encoder 401, the channel interleaver 402, and the modulator 403. MCS level selector 411 to be applied to; A demodulator (408) for demodulating the decoded data output from the BLAST decoder (406) by the channel estimate value; A channel deinterleaver (409) for channel deinterleaving demodulation data output from the demodulator (408); The decoder 410 decodes data output from the channel deinterleaver 409 and outputs information bits. The operation of the apparatus configured as described above will be described below.

First, the BLAST decoder 406 BLAST decodes the data received through the antenna and applies it to the channel / SNR estimator 407 and the demodulator 408, and the channel / SNR estimator 407 is the BLAST decoder ( The data output from 406 is input, the channel / SNR state information is estimated, and the channel / SNR state estimate is applied to the demodulator 408, the MCS level selector 411, and the transmit antenna selector 404.

Accordingly, the MCS level selector 411, based on the channel / SNR estimation value output from the channel / SNR estimator 407, the control signal for selecting the optimal scheme and coding type within the MCS threshold, the encoder ( 404, a channel interleaver 402, and a modulator 403, wherein the encoder 401, the channel interleaver 402, and the modulator 403 are selected by a control signal of the MCS level selector 411. The data is processed in an optimal manner and coding form within a threshold, that is, the encoder 401 encodes the transmission data and interleaves through the channel interleaver 402, and then modulates the data output from the channel interleaver 402. The modulated signal is output at 403.

Thereafter, the BLAST processing unit 405 sequentially receives the data output from the modulator 403 and outputs the data through the antenna selected by the transmitting antenna selection unit 404.

For reference, FIGS. 12 to 20 are state diagrams for comparing the performance when using the conventional AMC and STD, BLAST single method and the performance by STD + BLAST and AMC + STD + BLAST according to the present invention.

First, FIG. 12 shows FER (Frame Error Rate) and Through in AMC, and selects an optimal MCS level according to channel conditions.

Next, FIG. 13 shows error performance according to diversity, and in particular, it can be seen that the performance of the STD is better than that of the STTD in QPSK or 8PSK.

Next, FIG. 14 shows an error performance according to BLAST when two transmission antennas are used. FIG. 15 shows an error performance according to BLAST when four transmission antennas are used. In particular, FIG. 15 illustrates a method of performing only nulling except canceling. It is represented by INV, which performs only nulling by multiplying the received signal by the pseudo-inverse of the channel response matrix and performs the role of compensating for the effect of the channel by the ZF method.

At this time, in case of V-BLAST which performed both nulling and canceling, two nulling methods, MMSE and ZF, are considered.

Next, Figure 16 shows the performance when the AMC and the diversity (STTD, STD) is integrated in the present invention, it can be seen that the integration of the AMC and STD is significantly improved compared to the AMC.

17 shows the performance when the AMC and BLAST are integrated according to the present invention. It can be seen that the integration of the AMC and the BLAST rather than the AMC improves the performance in terms of transmission rate.

Next, FIG. 18 compares the performances of AMC, BLAST, and AMC and STD according to the present invention, and shows that the performance of the device incorporating AMC and BLAST is better in terms of transmission rate than the device incorporating AMC and STD. Can be.

Next, FIG. 19 shows the performance of a device integrating STD and BLAST according to the present invention, and it can be seen that the device combining STD and BLAST is more improved in terms of BER (Bit Error Rate) than the BLAST only device. .

20 shows the performance of a device combining AMC, STD, and BLAST according to the present invention, compared with that of a device combining BLAST with a single AMC and AMC, rather than AMC or AMC + BLAST (2 × 2 MMSE). AMC + STD + BLAST (2 of 4: 2 × 2 MMSE) performance shows the best performance in terms of transmission rate.

As described above, the adaptive modulation coding apparatus of the mobile communication terminal combines error performance and error performance by combining AMC (Bell-Lab Layered Space-Time) having an independent layer structure for each transmitting antenna. There is an effect of improving the forward link transmission rate.

Claims (2)

An encoder for encoding transmission data; A channel interleaver for interleaving data output from the encoder; A modulator for modulating data output from the channel interleaver; A transmit antenna selector which selects a transmit antenna for outputting data output from the modulator; A BLAST processing unit which sequentially receives the output data and outputs the data through the selected antenna; A BLAST decoder for BLAST decoding the data received through the antenna; A channel / SNR estimator which receives the BLAST decoded data and estimates channel state information and outputs the channel state information to a transmission antenna selector and a demodulator; A demodulator for demodulating the decoded data output from the BLAST decoder by the channel / SNR estimate value; A channel deinterleaver for channel deinterleaving demodulation data output from the demodulator; And a decoder for decoding the data output from the channel deinterleaver and outputting information bits. An encoder for encoding transmission data; A channel interleaver for interleaving data output from the encoder; A modulator for modulating data output from the channel interleaver; A transmission antenna selection unit for selecting a transmission antenna for outputting the modulated data based on a channel / SNR estimation value which is feedback information; A BLAST processing unit which sequentially receives data output from the modulator and outputs the data through the selected transmission antenna; A BLAST decoder for BLAST decoding the data received through the antenna; A channel / SNR estimator for receiving the BLAST decoded data and estimating channel state information; An MCS level selector for applying a control signal for selecting an optimal scheme and coding type within an MCS threshold to an encoder, a channel interleaver, and a modulator based on the channel / SNR estimate output from the channel / SNR estimator; A demodulator for demodulating the decoded data output from the BLAST decoder by the channel estimate value; A channel deinterleaver for channel deinterleaving demodulation data output from the demodulator; And a decoder for decoding the data output from the channel deinterleaver and outputting information bits.