KR101119106B1 - Method for Transmitting Signal Using AMC and Apparatus for Controlling AMC - Google Patents

Abstract

The present invention is a method for transmitting a signal by applying the adaptive modulation and coding (AMC), the margin value by using the channel state information for a certain time interval and the received error rate information according to the channel state A signal transmission method using an adaptive modulation and coding, comprising the steps of: calculating a; and compensating a reference adaptive modulation and coding (AMC) level using the margin value, and an apparatus for controlling the same. In a system for transmitting a signal by applying a method, there is an effect of providing an efficient information transmission by more actively coping with a channel environment change.

Adaptive Modulation and Coding (AMC), SINR Margin, CQI, PER

Description

Signal transmission method using adaptive modulation and coding and control device therefor {Method for Transmitting Signal Using AMC and Apparatus for Controlling AMC}

1 is a diagram illustrating an embodiment of a transmitter for adaptive modulation and coding (AMC).

2 is an embodiment configuration diagram illustrating a receiver for an AMC.

3 is a flowchart illustrating a method of transmitting a signal by applying AMC.

4 is a flowchart illustrating a method of transmitting a signal by applying AMC.

FIG. 5 is a diagram for explaining an AMC level determination method using CQI. FIG.

Figure 6 is an embodiment configuration diagram showing an AMC controller.

Fig. 7 is a diagram showing the difference probability division between SINR in AMC determination and SINR in packet transmission.

The present invention relates to a signal transmission method using adaptive modulation and coding and a control device therefor. More particularly, the present invention relates to a method and apparatus for adaptively determining AMC level in consideration of SINR margin and controlling modulation and coding. will be.

1 is a diagram illustrating an embodiment of a transmitter for adaptive modulation and coding (AMC). Referring to FIG. 1, the channel coding unit 11 adds information redundancy to input information bits. In this case, a channel encoder such as a turbo encoder or a convolutional encoder that supports a Forward Error Correction (FEC) function is used. The mapping unit 12 converts the channel coded bits into symbol information mapped to constellation. The AMC controller 14 uses the channel state information to control the appropriate coding and modulation by applying the AMC level according to the channel condition. For example, if the channel condition is bad, a more robust AMC level is chosen to allow channel coding and modulation to be performed. On the other hand, when the channel condition is good, channel coding and modulation are performed by selecting an AMC level capable of higher transmission speed. In addition, the transmission module 13 transmits the signal on which the channel coding and modulation is performed to the receiving side.

2 is a diagram illustrating an embodiment of a receiver for an AMC. Referring to FIG. 2, the reception module 21 receives a signal transmitted from a transmitter. In this case, current channel state information may be measured by measuring the received channel state. The signal received through the receiving module 21 is input to the demapping unit 22 to be converted into bit information, and the channel decoding unit 23 performs channel decoding.

As described above, AMC is a technique of adaptively determining and applying a coding rate and a modulation scheme to fit the current channel situation using channel state information. In general, the AMC level is determined by the combination of the coding rate and the modulation scheme, and the AMC controller 14 controls the coding rate and the modulation scheme to be applied according to the AMC level.

The AMC level may be determined at the receiving side or may be determined at the transmitting side. That is, since the current channel state can be measured at the receiving side, the AMC level can be determined at the receiving side using the measured channel state information. Meanwhile, the channel state information measured at the receiving side may be transmitted to the transmitting side, and the transmitting side may determine the AMC level using the channel state information.

3 is a flowchart illustrating a method of transmitting a signal by applying AMC. FIG. 3 illustrates an example of a process in which a transmitting side receives Channel Quality Information (CQI) from a receiving side to determine an AMC level. Referring to FIG. 3, the transmitter sets an initial AMC level (S31) and receives channel state information from the receiver (S32). The applicable AMC level is determined based on the received CQI (S33). For example, based on the CQI, it is determined whether the AMC set as the initial value can be applied, and accordingly, the AMC level is raised or lowered. Then, the coded and modulated signal is transmitted to the receiving side based on the determined AMC level (S34).

4 is a flowchart illustrating a method of transmitting a signal by applying AMC. 4 illustrates an example of a method in which a transmitting side receives an AMC level from a receiving side and applies the same to transmit a signal. In the example of FIG. 4, the transmitting side receives the AMC level information from the receiving side without determining the AMC level (S41). That is, the receiving side determines the AMC level based on the measured CQI, and then transmits the determined AMC level information to the transmitting side. The transmitting side transmits the coded and modulated signal to the receiving side based on the AMC level transmitted from the receiving side (S42).

FIG. 5 is a diagram for explaining an AMC level determination method using CQI. FIG. In the example of FIG. 5, Signal to Interference and Noise Ratio (SINR) is used as an example of CQI. In the example of FIG. 5, it is assumed that the AMC level is determined based on a packet error rate (hereinafter, referred to as 'PER') of 1%. In addition, assuming that the SINR of the received signal is measured as a value, in order to satisfy the current 1% PER, the AMC level should be at least B. In this case, therefore, B is determined at the AMC level. The AMC level determination process is performed by the transmitting side in the example of FIG. 3 and performed by the receiving side in the example of FIG. 4. The transmitter determines the AMC level B, or receives information indicating that the AMC level corresponds to B from the receiver, and transmits a signal to which the coding and modulation scheme corresponding to the determined AMC level B is applied.

As above, it is generally necessary to refer to the AMC table to determine the appropriate AMC level based on the CQI. Table 1 shows an example of the AMC table.

AMC level 0 One 2 3 4 5 6 7 8 SINR -0.9873 0.1394 3.0990 6.0232 9.2031 12.2468 16.6714 18.9036 21.3526

The sending side or receiving side determining the AMC level has an AMC table, such as the example in Table 1, corresponding to the CQI. The AMC table generally shows SINR values for each AMC level, based on a constant error rate (FER, BER or PER).

In the example of Table 1, select AMC level 0 if the SINR of the received signal is greater than -0.9873 dB and less than 0.1394 dB. On the other hand, if the SINR of the received signal is greater than 0.1394 dB and less than 3.0990 dB, AMC level 1 is selected.

As described above, when the AMC is applied, the following problems may occur. That is, a delay occurs between the time point at which the channel state is measured by receiving the signal as a reference of the measurement and the time point at which the AMC is applied according to the measured channel state information. Meanwhile, in a time varying channel, an error rate may be larger than a reference reception error rate (FER, BER, or PER). On the other hand, even when not a time-varying channel, there is a problem that the reception quality may be deteriorated when the receiver performance using the same AMC table is different compared to the SINR.

An object of the present invention is to apply an AMC that more accurately reflects a change in channel state when transmitting a signal by applying the AMC.

In order to achieve the above object, the present invention provides a method for transmitting a signal by applying Adaptive Modulation and Coding (AMC), and includes channel state information and reception error rate information according to channel state for a predetermined time interval. Calculating a margin value using the same, and compensating a reference adaptive modulation and coding (AMC) level using the margin value.

In addition, the present invention provides an adaptive modulation and coding control apparatus for transmitting a signal by applying Adaptive Modulation and Coding (AMC), comprising: a first information storage unit storing received error rate reference information according to a signal-to-noise ratio; And a second information storage unit for storing channel state information input in a predetermined time unit, the reception error rate reference information according to the signal-to-noise ratio stored in the first storage unit, and the channel state information stored in the second storage unit. A margin calculator for determining a noise ratio margin value and an adaptive modulation and coding level determiner for determining a compensated adaptive modulation and coding level by applying the margin value determined by the margin calculator to a reference adaptive modulation and coding level. Is done.

The above-mentioned objects, features and advantages will become more apparent from the following detailed description in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In order to compensate for the effects of the time delay between the CQI measurement time and the actual signal reception and the reception sensitivity different from receiver to receiver, a method of providing a certain margin to the CQI may be considered in constructing the AMC table. Hereinafter, SINR is used as an example of CQI.

Table 2 shows an example of the AMC table considering the SINR margin.

AMC level 0 One 2 3 4 5 6 7 8 SINR 1.10127 2.1394 5.0990 8.0232 11.2031 14.2468 18.6714 22.9036 23.3526

In the example of Table 2, a margin of 2 dB is given to the SINR value compared to Table 1. For example, if the measured SINR is greater than 1.10127 and less than 2.1394, then AMC level 0 is selected. If the measured SINR is greater than 2.1394 and less than 5.0990, AMC level 1 is selected. Therefore, by applying a lower AMC for the same SINR value, it is possible to ensure a more stable reference reception error rate. Hereinafter, a packet error rate (PER) will be used as an example of a reception error rate.

In the case of setting a constant margin as described above, if the channel does not change between the time of CQI measurement and the time of signal reception, the low AMC level is applied even though a high AMC level may be applied. This is not a signal transmission optimized for. On the other hand, when the channel state changes suddenly, even if the channel state suddenly deteriorates much, only a certain margin is guaranteed, so that the reception quality may deteriorate.

Thus, there is a need to adaptively determine the margin for the AMC table. 6 is a diagram illustrating an embodiment of an AMC controller. Referring to FIG. 6, the CQI information measured at the receiver is input to the SINR vs. PER information storage unit 142 and the CQI information storage unit 141 of the AMC controller 14. The SINR vs. PER information storage section 142 has a SINR vs. PER curve for each modulation scheme, as in the example of FIG. 5. Meanwhile, the CQI information storage unit 141 calculates a difference between the SINR at the time of AMC determination and the SINR at the time of packet transmission using the input channel state information.

7 illustrates an example of a probability probability distribution (PDF) between the SINR at the time of AMC determination and the SINR at the time of packet transmission. The CQI information storage unit 141 stores CQI information input in real time, accumulates it, and generates probability information as shown in the graph shown in FIG. 7. Since the CQI information is input in real time according to time, the probability distribution information illustrated in FIG. 7 is updated in real time, and the update period may be every frame or several frames.

Meanwhile, the margin calculator 143 calculates a margin to be applied to the AMC table by using the deviation information and SINR versus PER information. The AMC level determiner 144 compensates the SINR value of the AMC table stored in the AMC level determiner by using the margin information input from the margin determiner 143 and determines the AMC according to the compensated AMC table and channel state information. Controls the coding rate and modulation scheme of the signal to be transmitted. The AMC determiner initially stores an AMC table according to each receiver, and compensates the AMC table using a margin value input from the margin calculator 143 in real time from the start of communication, and uses the compensated AMC table. To determine the modulation and coding scheme.

For example, in the case where SINR vs. PER information is as shown in Table 3 and the deviation information is as shown in FIG. 7, the margin calculation method is as follows.

Table 3 shows SINR vs. PER value when channel coding is performed with QPSK modulation and 1/2 coding rate. Information as shown in Table 3 is stored in the SINR to PER information storage unit 142 shown in FIG.

SINR (dB) 0.0 1.0 2.0 3.0 4.0 PER 0.9 0.558 0.2 0.013 0.0004

Referring to Table 3, the SINR satisfying the 1% PER is 3 dB. At this time, when two frames are delayed, there is a deviation as shown in FIG. The deviation probability as shown in FIG. 7 may be calculated by the CQI storage unit 141 of FIG. 6 using the CQI information received for a predetermined time. Meanwhile, the margin calculator 143 may perform the CQI stored in the CQI storage 141 for a predetermined time.

When the PER value is calculated, Equation 1 is obtained.

는 2 프레임 지연 후의 PER 값을 의미한다. 수학식 1 과 같이,

값은 각각의 편차 확률

에 해당하는 PER 값

을 곱하고 이를 합산함으로써 계산할 수 있다. 즉,

= 0.013*0.18 + 0.0004*0.16 + 0.2*0.16 + 0.558*0.1 + 0.9*0.06 + 1.0*0.03 + 1.0*0.02 = 0.1942 가 된다. In Equation 1

Denotes the PER value after 2 frame delays. As in Equation 1,

The value is the probability of each deviation

PER value corresponding to

It can be calculated by multiplying and summing them. In other words,

= 0.013 * 0.18 + 0.0004 * 0.16 + 0.2 * 0.16 + 0.558 * 0.1 + 0.9 * 0.06 + 1.0 * 0.03 + 1.0 * 0.02 = 0.1942

In the above example, the current 1% PER is satisfied, but after a delay of two frames, the PER becomes 19.4%. Therefore, even when two frames are delayed, the AMC table is updated by calculating a margin value to satisfy 1% PER. Then, according to the updated table, the AMC level is controlled. On the other hand, when the SINR vs. PER graph according to each AMC level has a parallel movement form, instead of determining all SINR vs. PER values corresponding to each AMC level, only the SINR vs. PER graph corresponding to one AMC level may be stored. have.

In the above, an example has been described in which an AMC controller is provided at a transmitting side to control channel coding and modulation schemes of a direct transmission signal. However, when the AMC controller is provided at the receiving side, AMC can be performed by transmitting the AMC level information determined by the AMC determining unit to the transmitting side.

8 is a flowchart illustrating a method of transmitting a signal according to an AMC level considering margins. Referring to FIG. 8, the transmitter sets an initial AMC level according to the characteristics of the receiver (S81). Then, channel state information is received from the receiving side. Since the received channel state information at this time is a value measured for a transmission signal, it may be regarded as a value for a channel state before a predetermined frame. The margin to be applied to the AMC table is calculated using the channel state (S83). At this time, the margin is calculated according to the deviation probability cumulatively calculated from a certain time point in the past to the present. The AMC level is determined in consideration of the margin (S84), and the signal is transmitted by applying the determined AMC level.

On the other hand, when receiving and applying the AMC level information to the transmission signal, the receiving side calculates a margin to be applied to the AMC table using the channel state, and transmits the AMC level information determined in consideration of the margin to the transmitting side. do. The transmitter then transmits the signal by applying the received AMC level.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

The present invention has the effect of providing efficient information transmission by coping more actively with channel environment changes in a system for transmitting signals by applying AMC.

Claims (15)

In a method for transmitting a signal by applying the adaptive modulation and coding (AMC), Calculating a margin value using the channel state information input in a predetermined time unit and the reception error rate information according to the channel state; And Compensating for a reference adaptive modulation and coding (AMC) level using the calculated margin value, The channel state information is a signal to interference noise ratio (SINR), The received error rate information according to the channel state is a signal-to-interference noise ratio (SINR) -received packet error rate (PER) graph (curve), The signal-to-interference noise ratio (SINR) -receive packet error rate (PER) graph includes a signal-to-interference noise ratio (SINR) -receive packet error rate (PER) graph corresponding to each adaptive modulation and coding (AMC) level, The predetermined time unit is a signal transmission method using adaptive modulation and coding, characterized in that the frame (frame) unit. delete delete delete The method of claim 1, The reference adaptive modulation and coding (AMC) level is a combination of a coding rate (modulation scheme) and a modulation scheme (modulation scheme) characterized in that the signal transmission method using adaptive modulation and coding. The method of claim 5, Computing the margin value, Storing the deviation between the channel state information input in the predetermined time unit and the channel state information during transmission; Calculating a probability of deviation using the stored deviation; And And calculating the margin value by using the calculated deviation probability and the received error rate information according to the channel state. The method of claim 6, And transmitting the signal by applying the compensated reference adaptive modulation and coding (AMC) level. The method of claim 7, wherein And transmitting the compensated adaptive modulation and coding (AMC) level information. In a method for transmitting a signal by applying the adaptive modulation and coding (AMC), Measuring channel state information using the received signal; The measured channel state information and channel state during transmission Comparing the information to calculate a deviation; Calculating the probability distribution of the deviation by repeating the measuring channel information and calculating the deviation for a predetermined time interval; Calculating a margin value for an adaptive modulation and coding (AMC) table using the calculated probability distribution and received error rate information according to channel conditions; Modifying the adaptive modulation and coding (AMC) table by applying the calculated margin value; And Determining an adaptive modulation and coding (AMC) level according to the modified modulation and coding (AMC) table. In the adaptive modulation and coding control device for transmitting a signal by applying the adaptive modulation and coding (AMC), A first information storage unit storing reception error rate reference information according to a signal-to-noise ratio; A second information storage unit which stores the channel state information input in a predetermined time unit; A margin calculator configured to determine a signal-to-noise ratio margin value using received error rate reference information according to the signal-to-noise ratio stored in the first storage unit and channel state information stored in the second storage unit; And And an adaptive modulation and coding level determiner configured to determine a compensated adaptive modulation and coding level by applying a margin value determined by the margin calculator to a reference adaptive modulation and coding level. The received error rate reference information according to the signal-to-noise ratio is a Signal to Interference and Noise Ratio (SINR) versus Packet Error Rate (PER) graph (curve), The predetermined time unit is an adaptive modulation and coding control device, characterized in that the frame (frame) unit. delete delete 11. The method of claim 10, The margin calculator calculates a deviation probability by using the deviation between the channel state information input in the predetermined time unit and the channel state information during transmission, and uses the received error rate reference information according to the calculated deviation probability and the signal-to-noise ratio. Adaptive modulation and coding control apparatus for calculating the margin value. The method of claim 13, A signal processor configured to perform coding and modulation by applying the determined adaptive modulation and coding level to an input signal; And A transmission module for transmitting the processed signal Adaptive modulation and coding control device further comprising. The method of claim 13, And a transmitting module for transmitting the determined adaptive modulation and coding level information to a transmitting side.

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