KR20090015621A - Apparatus and method for transmission and reception of control information in mobile telecommunication system - Google Patents

Abstract

A transmitter and a receiver of control information and a method in a mobile communications system for reducing bit error rate or the block error rate in case of correcting the error of important data and improving the reliability are provided to improve the reliability of control information transmitted to PUCCH(Physical Uplink Control Channel) in 3G LTE. The encoded bit b(i) produces a modulation symbol through a modulation process(202). The modulation process is determined according to a modulation system. And the modulation symbol modulated according to the predetermined modulation system is comprised of the coded bits of x. An SC-FDMA symbol in which the pilot is mapped of 10 totals except the SC-FDMA symbol of 4 is used as the control information transmission frame. The critical information is mapped in the pilot symbol peripheral unit as the physical channel mapping operation(203) relatively in order to well maintain the channel estimation capability against the critical information.

Description

Apparatus and method for transmitting and receiving control information in mobile communication system {APPARATUS AND METHOD FOR TRANSMISSION AND RECEPTION OF CONTROL INFORMATION IN MOBILE TELECOMMUNICATION SYSTEM}

The present invention relates to an apparatus and method for transmitting and receiving control information in a mobile communication system, and more particularly, to an apparatus and method for transmitting and receiving control information transmitted on an uplink in a mobile communication system.

In general, mobile communication systems have been developed to provide communication while guaranteeing activity to users. Due to the rapid development of technology, such a mobile communication system is developing in a form capable of providing high speed data communication as well as voice communication.

In recent mobile communication systems, orthogonal frequency division multiple access (OFDMA), or a similar method, is useful for high-speed data transmission in a wireless channel. Frequency Division Multiple Access (hereinafter referred to as "SC-FDMA") is being actively researched. Currently, the 3rd Gerneration Partnership Project (3GPP), an asynchronous cellular mobile communication standard organization, is studying a next-generation mobile communication system, Long Term Evolution (LTE) or Evolved Universal Terrestrial Radio Access (E-UTRA), based on the multiple access method.

In the multiple access scheme as described above, data or control information of each user is divided by assigning and operating such that time-frequency resources for carrying data or control information for each user do not overlap each other, that is, orthogonality is established. do. In the case of the control channel, an additional code resource may be allocated to distinguish control information of each user.

In the LTE system, uplink control information includes ACK (Acknowledgement) / NACK (Negative ACK) feedback information, which is a signal for responding to successful reception of downlink data transmission, and CQI (Channel Quality Indication) for feeding back downlink channel status. Information), feedback information required for MIMO operation, or a combination of the ACK / NACK, CQI, and MIMO feedback information. The ACK / NACK information is generally composed of 1-bits. The ACK / NACK information is repetitively transmitted several times in order to improve reception performance and expand cell coverage. In addition, in a system to which MIMO is applied, ACK / NACK information is transmitted for each MIMO codeword. In general, the CQI information is composed of a plurality of bits to represent a channel state, and is channel-coded and transmitted for improving reception performance and cell coverage. The channel coding method for the CQI information may be a block coding or a convolutional coding scheme.

In the case of the control information composed of a plurality of bits, such as the CQI, a method of increasing reception reliability for the significant bits may be performed by channel coding different error correction capabilities for each bit position constituting the control information. For example, in the HSDPA (High Speed Downlink Packet Access) system, a channel encoding of CQI information consisting of 5 bits using (20, 5) block coding is performed, but a strong channel encoding method is applied for 1 bit of the Most Significant Bit (MSB). Doing.

In the LTE system, uplink control information is classified according to whether data is transmitted or not. When data and control information are simultaneously transmitted through uplink, the data and control information are time-division multiplexed (TDM) and mapped to the time-frequency resource allocated for data transmission. On the other hand, when only control information is transmitted without data transmission, a specific allocated frequency band is used for control information transmission. As discussed in the standard meeting to date, a physical channel for transmitting only the control information is defined as a physical uplink control channel (PUCCH), and the PUCCH is mapped to the assigned specific frequency band.

FIG. 1 is a diagram illustrating a transmission structure of a PUCCH, which is a physical channel for transmitting control information in uplink in a current 3GPP LTE system. Hereinafter, a detailed transmission structure of the PUCCH will be described with reference to FIG. 1.

In FIG. 1, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The time domain is in one subframe 102, and the frequency domain is in system transmission bandwidth 110. The subframe 102, which is a basic transmission unit of the uplink, has a length of 1 ms, and one subframe includes two slots 104 and 106 each having a length of 0.5 ms. Each slot 104, 106 is composed of a plurality of SC-FDMA symbols 111-123, 131-143. 1 illustrates an example in which one slot is composed of seven SC-FDMA symbols. The smallest unit of the frequency domain is a subcarrier, and the basic unit of resource allocation is a resource block (hereinafter referred to as "RB") 108, 109. The RBs 108 and 109 are composed of a plurality of subcarriers and a plurality of SC-FDMA symbols. Here, 14 SC-FDMA symbols constituting 12 subcarriers and 2 slots is shown as an example of one RB. Referring to FIG. 1, the frequency band to which the PUCCH is mapped corresponds to the reference numeral 108 or the reference numeral 109 which are RBs corresponding to both ends of the system transmission band 110. The PUCCH may apply frequency hopping to increase frequency diversity during one subframe. In this case, slot hopping is possible.

This will be described with reference to FIG. 1. Control information # 1 is transmitted over the pre-allocated frequency band 108 in the first slot 104, and then in the second slot 106 is a frequency hopping over the other pre-assigned frequency band 109. Control information # 2, on the other hand, is transmitted on the pre-allocated frequency band 109 in the first slot 104, and then in the second slot 106, is the frequency hopping and transmitted on the other pre-allocated frequency band 108. do.

In FIG. 1, SC-FDMA symbols, reference numerals 111, 113, 114, 115, 117, 138, 140, 141, 142, 144 or reference numerals 131, 133, 134, 135, 137, in one subframe 102 are illustrated. Control information is transmitted to 118, 120, 121, 122, and 124, and pilot, reference signal (RS) to SC-FDMA symbol, reference numerals 112, 116, 139, 143, or reference numerals 132, 136, 119, and 123. (Also referred to collectively) is shown. The pilot consists of a predetermined sequence and is used for channel estimation for coherent demodulation at the receiving end. The number of SC-FDMA symbols for control information transmission, the number of SC-FDMA symbols for RS transmission, and a corresponding position in a subframe are examples and may be changed according to the type of control information to be transmitted or system operation.

When the control information is transmitted through the PUCCH in the LTE system operating as described above, it is necessary to define a specific transmission method for increasing the reception reliability of the control information. However, until now, when the control information is transmitted through the PUCCH in the LTE system, a specific method for increasing the reception reliability of the control information has not been proposed.

Accordingly, the present invention provides a transmission and reception apparatus and method for increasing the reliability of control information transmitted in the reverse direction in a mobile communication system.

The present invention provides a transmission and reception apparatus and method for increasing the reliability of control information transmitted over a PUCCH in a 3G LTE system.

The present invention provides an apparatus and method for transmitting and receiving control information that can increase the reliability of control information transmitted in the reverse direction, thereby preventing unnecessary retransmissions and improving system efficiency.

According to an aspect of the present invention, there is provided a method for transmitting control information in a reverse direction in a mobile communication system, the method comprising: encoding control information according to an uneven error protection method, modulating the encoded symbols, And mapping the modulated symbols to physical channels based on the channel estimation capability.

An apparatus according to an embodiment of the present invention is an apparatus for transmitting control information in a reverse direction in a mobile communication system, the encoder encoding the transmitted information according to an unequal error protection method, a modulator for modulating the encoded symbols, and the modulation. And a mapper for controlling the mapped symbols to be mapped to the physical channel based on the channel estimation capability, and a mapper for mapping the symbols modulated by the control of the controller.

The present invention provides a method for transmitting / receiving control information in a case of increasing the reception reliability of a specific bit of control information to be transmitted, thereby reducing the bit error rate or block error rate and improving reliability when correcting an error of important data. There is.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification. In addition, the present invention described below will specifically describe an operation in which a terminal transmits control information in an uplink in a cellular communication system based on an LTE system. However, the operating principle of the present invention is based on a specific transmission system or a transmission direction of control information ( Note that it is not limited to uplink or downlink).

The present invention provides a method for increasing reception reliability for a specific bit of control information to be transmitted. The control information may include acknowledgment (ACK) / negative ACK (NACK) feedback information, a signal for responding to successful reception of the received data, channel quality indication (CQI) information for feeding back channel status, and multiple input / output antennas. MIMO: Feedback information required for MIMO operation, or a combination of the ACK / NACK, CQI, and MIMO feedback information. The ACK / NACK information is generally composed of 1-bits. The ACK / NACK information is repetitively transmitted several times in order to improve reception performance and expand cell coverage. In a system to which MIMO is applied, ACK / NACK information is transmitted for each MIMO codeword. In general, the CQI information is composed of a plurality of bits to represent a channel state, and is channel-coded and transmitted for improving reception performance and cell coverage. Block coding is assumed as a channel coding method for the CQI information.

In the case of control information consisting of a plurality of bits such as CQI, a method for increasing reception reliability for a significant bit is needed. For example, if the channel state to be expressed as CQI is composed of a plurality of bits, the system recognizes the least significant bit (LSB) incorrectly compared to the case where the receiving terminal incorrectly recognizes the Most Significant Bit (MSB). Has little impact on system performance. Therefore, high reception reliability is required for the MSB if possible. Therefore, there is a method of strongly adding error correction capability to significant bits in the channel encoding step. Hereinafter, a method of strongly adding error correction capability to a significant bit is referred to as "method 1". For example, a high speed downlink packet access (HSDPA) system uses channel coding for CQI information consisting of 5 bits using (20, 5) block coding, but strongly channel codes for 1 bit of MSB. The (20, 5) block coding for CQI applied in HSDPA will be described in more detail as follows.

The (20,5) code for encoding CQI of HSDPA (High Speed Downlink Packet Access) defined in 3GPP standard TS25.212 uses the base sequence shown in Table 1 below.

i M _{i, 0} M _{i, 1} M _{i, 2} M _{i, 3} M _{i, 4} 0 One 0 0 0 One One 0 One 0 0 One 2 One One 0 0 One 3 0 0 One 0 One 4 One 0 One 0 One 5 0 One One 0 One 6 One One One 0 One 7 0 0 0 One One 8 One 0 0 One One 9 0 One 0 One One 10 One One 0 One One 11 0 0 One One One 12 One 0 One One One 13 0 One One One One 14 One One One One One 15 0 0 0 0 One 16 0 0 0 0 One 17 0 0 0 0 One 18 0 0 0 0 One 19 0 0 0 0 One

In addition, by using Equation 1 below, (20,5) channel encoding may be applied by a linear combination of five base code strings having a length of 20 and input information consisting of 5 bits. It becomes possible.

(i = 0, ..., 19)

(i = 0, ..., 19)

Here, a _n is the nth information bit to be encoded, where a ₀ is LSB and a ₄ is MSB. B _i is an i-th output bit in which channel encoding is performed on information bits and is encoded. Thus, 20 bits of encoded bits are generated from 5 bits of input information. In particular, the base code string exemplified in Table 1 is characterized by additionally providing an error correction capability to a ₄ , which is the MSB. Specifically, the base code sequence is a base code M _{i, n} (i = 15, 16, 17, 18, 19, n = 0, 1, 2, 3, to generate the 15th to 19th output bits b15 to b19). 4) of M _{i, 4} = 1 (i = 15, 16, 17, 18, 19) and all others are set to 0, resulting in multiplication of M _{i, 4} by Equation 1 above. The effect is to repeat MSB a ₄ five times. That is, the (20, 5) block coding is an error for the MSB a ₄ by performing an operation equivalent to the operation of additionally repeating the MSB a ₄ 5 times after performing (15, 5) block coding on 5 bits of input information. Give additional correction ability.

Further granting error correction capability to the information bit at a specific position as described above is called Unequal Error Protection (hereinafter referred to as "UEP"). By appropriately constructing the base code string, it is determined at which position the information bits are additionally given some error correction capability.

In the LTE system, (N, K) block coding having UEP characteristics as described above may be applied to CQI information transmission. In this case, N represents the size of the encoded bit string, and K represents the size of the input bit string.

Next, a method of mapping a modulation symbol including significant bits of the control information to a position where channel estimation is relatively accurate when mapping the encoded and modulated symbols for the control information to a physical channel will be described. In the following description, the method is referred to as "method 2".

Referring to the transmission structure of FIG. 1, control information is transmitted through a pre-allocated frequency band 108 in the first slot 104, and then another frequency band pre-allocated by being frequency hopping in the second slot 106. A case of transmitting through 109 will be described as an example. FIG. 1 illustrates a specific SC-FDMA symbol, that is, a pilot (also referred to as a pilot, reference signal (RS)), is mapped to a reference SC 112, 116, 139, and 143 within one subframe, and transmitted. For example, reference numbers 111, 113, 114, 115, 117, 138, 140, 141, 142, and 144 show an example in which control information is mapped and transmitted. The number of SC-FDMA symbols for control information transmission, the number of SC-FDMA symbols for RS transmission, and the corresponding positions in a subframe are examples and may be changed according to the type of control information to be transmitted or system operation. The channel state of the wireless transmission path through which the control information is transmitted is estimated from a pilot composed of a sequence promised between the transceivers and compensated for the received signal, so that the receiver acquires the control information. Therefore, the higher the accuracy of channel estimation, the higher the reception reliability of the control information. When the pilot and the control information share and share the limited radio resources as shown in FIG. 1, the receiver needs a channel estimation method for inferring the channel value for the time period in which the pilot is not mapped from the symbol to which the actual pilot is mapped. Do. In the example of FIG. 1, the channel estimation for the control information transmitted through the first slot 104 and the pre-assigned frequency band 108 is generally mapped to the SC-FDMA symbols 112 and 116 and transmitted. A channel estimate for control information, which is made by interpolating pilots and is transmitted over the second slot 106 and the frequency hopping pre-allocated frequency band 109, is generally referred to as SCs 139 and 143. -By interpolating pilots that are mapped and transmitted to the FDMA symbol. In the channel estimation method using interpolation, symbols having a large distance from the pilot used for interpolation generally have low channel estimation capability, whereas channel estimation capability for symbols located around the pilot used for interpolation is excellent. There is this. For example, in the example of FIG. 1, the channel estimation capability of each SC-FDMA symbol position for the control information transmitted through the first slot 104 and the pre-assigned frequency band 108 is a pilot-mapped SC-FDMA symbol. Phosphorus, has excellent properties in the periphery of reference numerals 112 and 116, in particular in the SC-FDMA symbol mapped to the positions 113 and 115 located between two pilot symbols. And the channel estimation capability of each SC-FDMA symbol position for the control information transmitted through the second slot 106 and the pre-assigned frequency band 109 is a reference number 139, 143, which is a pilot-mapped SC-FDMA symbol. It has excellent characteristics in the periphery of, in particular the SC-FDMA symbol mapped to the positions of reference numerals 140 and 142 located between the two pilot symbols.

Therefore, when mapping the encoded and modulated symbols to physical channels, the control information to be transmitted by mapping the modulation symbols including the significant bits of the control information to a position having a relatively high channel estimation capability in consideration of the characteristics. It is possible to increase reception reliability for the significant bits of.

In the present invention, the method 1 and the method 2 described above are synthesized and designed to increase reception reliability of important bits of control information to be transmitted by the following method through channel encoding and symbol mapping. .

2 is a conceptual diagram illustrating a process of mapping control information to a physical channel according to the present invention. Hereinafter, the overall operation of the present invention will be described with reference to FIG. 2.

First, channel coding 200 control information to be transmitted. As described above, the channel coding is performed by applying (N, K) block coding having UEP characteristics. The (N, K) block coding has a result equivalent to the result of concatenating (N1, K) block coding with (N2, K ') block coding. In this case, N denotes the size of the encoded bit string, K denotes the size of the input bit string, and N = N1 + N2 and K> K '. That is, in encoding K bits of control information, the error correction capability of the K bits of the input information is relatively excellent. A base sequence having an optimal performance with respect to (N, K) block coding having the UEP characteristics is a value determined according to N, K, N1, N2, K 'values, and the like. Denotes the base code string for (20, 5) block coding, which makes the error correction capability relatively strong for MSB 1 bit of input information. The (N, K) block coding operation is performed by linear combination of input information consisting of K base code strings of length N and K bits, and can be expressed by Equation 2 below. In Equation 2, a (n) is the nth information bit to be encoded, where a (0) is a Least Significant Bit (LSB) and a (K-1) is a Most Significant Bit (MSB). b (i) is an i-th output bit in which channel encoding is performed on input information bits, that is, encoded bits. And M _{i, n} represents a base code used for the (N, K) block coding.

(i = 0, 1, ... , N - 1)

(i = 0, 1, ..., N-1)

The last N2 bits 201 of the encoded bits b (i), that is, b (N-N2), b (N-N2 + 1),... , b (N-2) and b (N-1) serve to provide additional error correction capability to the K 'bit among the K bits of input information.

Thereafter, the encoded bits b (i) generate a modulation symbol through a modulation process in step 202. The modulation process is determined according to a modulation scheme, and a modulation symbol modulated according to a predetermined modulation scheme consists of contiguous x encoded bits. For example, x = 1 when using the BPSK modulation method, x = 2 when using the QPSK modulation method, x = 3 when using the 8PSK modulation method, and x = 4 when using the 16QAM modulation method. do.

Hereinafter, for convenience of description, it is assumed that a structure of a subframe in which the control information is mapped and transmitted is shown in FIG. 1. Then, a total of 10 SC-FDMA symbols except for 4 SC-FDMA symbols to which a pilot is mapped in one subframe can be used for the control information transmission. Accordingly, modulation symbols for a total of 10 control information can be mapped to the 10 control information transmission SC-FDMA symbols for transmission. That is, in FIG. 2, physical channel mapping operation 203 is performed. The physical channel mapping operation 203 maps the critical information to the pilot symbol periphery in order to maintain a relatively good channel estimation capability with respect to the critical information as described in Method 2. FIG. 2 shows an arbitrary modulation scheme for the coded bits of the control information to be transmitted, so that the last N2 bits 201 among the hatched bits b (i), that is, "b (N-N2), b ( Modulation symbols consisting of N-N2 + 1, ..., b (N-2), b (N-1) ", for example, m (6), m (7), m (8), m (9). ) Is shown by reference numeral 204.

Accordingly, SC-FDMA symbols s (1), s (3), and s (6), which are positions having excellent channel estimation capability, are represented by the modulation symbols m (6), m (7), m (8), and m (9). ) and s (8) (205, 206, 207, 208), respectively, so that the control information K 'bits constituting the modulation symbols m (6), m (7), m (8), and m (9). This improves the reception reliability for the system and improves the overall system performance. It utilizes the feature that can separate only the information about a specific input bit from the output bit stream of block coding with UEP characteristics.In the case of general block coding, information about all input bits is mixed in the output bit stream of block coding. Because of this, the information for a particular input bit cannot be separated. In FIG. 2, the remaining modulation symbols m (0), m (1), m (2), m (3), m (4) and m (5) are SC-FDMA symbols s (0) and s (2), respectively. ), s (4), s (5), s (7), and s (9).

Meanwhile, in order to obtain an effect equivalent to the above-described physical channel mapping operation, an interleaving operation for modulation symbols may be defined. That is, the modulation symbols m (0), m (1), m (2), m (3), m (4), m (5), m (6), m (7), m (8), By interleaving m (9) so that the control information is sequentially mapped to a subframe in which the control information is transmitted, the interleaving operation is defined so that the above-described important control information can obtain a relatively excellent channel estimation capability. For example, the interleaving result is m (0), m (6), m (1), m (7), m (2), m (3), m (8), m (4), m (9), By defining m (5), the interleaved modulation symbols may be sequentially mapped to a subframe in which the control information is transmitted, so that important control information may have a relatively good channel estimation capability.

3 and 4 are flowcharts illustrating operations of transmitting control information according to an embodiment of the present invention. Hereinafter, an operation process of transmitting control information according to the present invention will be described with reference to FIGS. 3 and 4.

First, FIG. 3 will be described. The transmitter generates control information to be transmitted in step 300. Thereafter, the transmitter encodes the control information generated in step 302 to have a UEP characteristic. Since the above-described UEP characteristics have been described above, they will not be further described herein. The transmitter modulates the symbol encoded to have the UEP characteristic as described above in step 304 and maps it to the corresponding physical channel in step 306. In performing the mapping on the physical channel, as described above, some important bits of the control information are controlled to be mapped to a position having excellent channel estimation capability. Thereafter, the mapped control information is transmitted as described above.

Next will be described with reference to FIG. The transmitter generates control information to be transmitted in step 400. Thereafter, the transmitter encodes the control information generated in step 402 to have a UEP characteristic. Since the above-described UEP characteristics have been described above, they will not be further described herein. The transmitter modulates the symbol encoded to have the UEP characteristic as described above in step 404, and performs interleaving in step 406. At this time, interleaving is performed to interleave the interleaving output for the modulation symbol such that some significant bits of the control information are mapped to a position having a relatively good channel estimation capability. Thereafter, the transmitter proceeds to step 408 to map the interleaved symbols to the physical channel, and transmits the mapped control information through the physical channel in step 410.

When the control information described above is transmitted, the receiver may express the reception operation of the control information in reverse order and reverse operation with respect to the above-described series of operations. Next, the operation received by the receiver will be described with reference to the accompanying drawings.

5 and 6 are flowcharts illustrating operations when receiving control information according to an embodiment of the present invention. 5 is a diagram of a reception operation corresponding to FIG. 3, and FIG. 6 is a diagram of a reception operation corresponding to FIG. 4.

The receiver receives a predetermined signal in step 500. Since only the control information is examined here, it is assumed that the received signal means a signal including the control information. When the signal having the control information is received as described above, the receiver performs physical channel demapping in step 502 to extract the modulation symbol for the control information from the physical channel to which the control information is mapped. In the extraction operation, the receiver performs channel estimation and channel compensation on the received signal from the received pilot symbol and then reconstructs the modulation symbols in the original order. Thereafter, the receiver demodulates the reconstructed modulation symbol in operation 504, and obtains control information by decoding the demodulated symbol in operation 506.

Next, the reception operation of FIG. 6 corresponding to FIG. 4 will be described. The receiver receives a predetermined signal in step 600. Since only the control information is examined here, it is assumed that the received signal means a signal including the control information. When the signal having the control information is received as described above, the receiver extracts a modulation symbol for the control information from the physical channel to which the control information is mapped from the signal received through physical channel demapping in step 602. In the extraction operation, the receiver performs channel estimation and channel compensation on the received signal from the received pilot symbol. In operation 604, the receiver performs a deinterleaving operation to reconstruct modulation symbols in the original order on the extracted signal. In step 606, the receiver demodulates the reconstructed modulation symbol, and in step 608, demodulates the demodulated symbol to obtain control information transmitted by the transmitter.

<First Embodiment>

The first embodiment is an example in which control information consisting of 5 bits is (20, 5) block coded and mapped to PUCCH (Physical Uplink Control Channel) which is a physical channel for transmitting the control information. It demonstrates with reference.

7 is a conceptual diagram illustrating a process of mapping control information to a physical channel according to the first embodiment of the present invention.

The (20, 5) block coding has a feature of having a relatively high error correction capability for the MSB 1 bit 708 of the input control information, and the basis sequence is shown in Table 1 above. Same as one. The control information is a control information consisting of a plurality of bits, for example, CQI information for feeding back channel status, feedback information for operating multiple input / output antennas, or ACK / NACK feedback which is a response signal for the CQI information and received data. It may be a combination of information, or a combination of the control information. When the control information is composed of a combination of CQI information and ACK / NACK feedback information, since high reception reliability is generally required for the ACK / NACK feedback information, the ACK / NACK is configured to be mapped to the MSB. In step 702, a process of encoding a (0) to a (4), which is control information consisting of the 5 bits, is applied by applying the base code string shown in Table 1. Accordingly, when encoding is performed as described above, a total of 20 bits of encoded bits b (0) to b (19) are generated. Among the encoded bits, b (15) to b (19) 710 represent a result of being repeated five times for a (4), which is an MSB, among input control information. Accordingly, the (20, 5) block coding provides additional error correction capability for the MSB a (4) of the input control information.

In step 704, the encoded bit is modulated to generate a modulation symbol. Applying QPSK modulation to this modulation method, for example, generates one modulation symbol from two consecutively coded bits. That is, a modulation symbol m (0) is generated from the encoded bits b (0) and b (1), and a modulation symbol m (1) is generated from the encoded bits b (2) and b (3). M modulation symbols m (0) to m (9) are generated. Thus, modulation symbols m (7), m (8) and m (9) 712 are coded bits b (15) to b (19) (710) which give additional error correction capability for the MSB a (4). ) Contains information about. Therefore, in step 706 of performing physical channel mapping, when the modulation symbols are mapped to the PUCCH, modulation symbols m (7), m (8), and m (9) including information on MSB a (4) are possible as much as possible. By further mapping the channel estimation capability to a relatively excellent position, the reception reliability of a (4) is further increased.

If the structure of the PUCCH to which the control information is mapped is a structure in which two pilot symbols exist in one slot and thus there are four pilot symbols 716, 724, 730, and 738 in one subframe, channel estimation is performed for each slot. In general, the channel estimation capability tends to be relatively good at positions nearest to each pilot symbol between two pilot symbols in each slot (718, 722, 732, and 736). Therefore, a modulation symbol including information about a modulation symbol for improving reception reliability or some specific control information bits for improving reception reliability is preferentially mapped to the positions of the reference numerals 718, 722, 732, and 736, and then the remaining symbols are mapped. The modulation symbols are mapped to positions other than the position where the modulation symbol including the information about the modulation symbol to increase the reception reliability or some specific control information bits to increase the reception reliability is mapped.

In the example of FIG. 7, modulation symbols m (7) are mapped to s (1) 718, m (8) to s (3) 722, and m (9) to s (6) 732, respectively. The remaining modulation symbols m (0) to m (6) are shown to be sequentially mapped to positions where m (7), m (8) and m (9) are not mapped.

More generally, x is the number of points where the channel estimation capability is relatively excellent during the time interval in which the control information is transmitted, and for the modulation symbol for increasing reception reliability or for some specific control information bits for increasing reception reliability. When the number of modulation symbols including information is y and the total number of modulation symbols is z;

1) If x = y,

One-to-one mapping the y modulation symbols to the x different positions, respectively.

map z-y modulation symbols to positions where the y modulation symbols are not mapped, respectively.

In addition, z-y modulation symbols mapped as described above may be mixed for randomization. That is, z-y modulation symbols may be interleaved with each other.

2) If x <y

Select x modulation symbols from the y modulation symbols and map them one-to-one to the x different positions.

map z-x modulation symbols to positions where the x modulation symbols are not mapped, respectively.

In addition, z-x modulation symbols mapped as described above may be mixed for randomization. That is, z-x modulation symbols may be interleaved with each other.

3) If x> y,

Select and map some of the y modulation symbols from the x different positions, respectively. The y positions selected from the x different positions are dropped as much as possible, so that the mapped modulation symbols can be compensated with the remaining symbols even if some channel environment is suddenly bad.

map z-y modulation symbols to positions where the y modulation symbols are not mapped, respectively.

In addition, z-y modulation symbols mapped as described above may be mixed for randomization. That is, z-y modulation symbols may be interleaved with each other.

The time interval in which the control information is transmitted is generally one subframe, and may be composed of a plurality of subframes for transmitting a large amount of control information. The mapping operation may be implemented as an interleaving operation having the same effect.

8 is a block diagram of an apparatus for transmitting control information according to an embodiment of the present invention.

Referring to FIG. 8, the control information generating device 802 receives information on which control information to transmit from the controller 810 and generates corresponding control information according to a format of control information to be transmitted. For example, when transmitting CQI information consisting of 5 bits, CQI information is generated from downlink channel state information received from the controller 810. The control information generating device 802 may be included in the control unit 810. The channel encoder 804 receives the type of control information to be encoded from the control unit 810, and according to the type of control information, the encoding rate and the UEP degree of the predetermined control information, and the UEP among the input control information. Channel encoding is performed by reflecting information such as specific bit information that is intended. In the first embodiment, the generated 5-bit CQI information is added with error correction capability through the (20, 5) block coding (804), where additional error correction capability is added to the MSB of the CQI information. The channel coded signal is generated as a modulation symbol in the modulator 806. A QPSK scheme is generally applied to the CQI information. The physical channel mapper 808 performs an operation of mapping the generated modulation symbols to PUCCH, which is a physical channel for transmitting control information. Specifically, the mapping operation preferentially maps a modulation symbol including information about a modulation symbol for increasing reception reliability or some specific control information bits for improving reception reliability to a location having a relatively good channel estimation capability. The remaining modulation symbols may be sequentially mapped to positions where the modulation symbols are not mapped. Alternatively, the mapping positions may be mixed with the remaining modulation symbols to obtain additional randomization effects. The controller 810 provides a specific mapping rule that defines a mapping operation of modulation symbols based on the channel estimation capability of each time interval position from the physical channel mapper 808.

9 is a block diagram of an apparatus for transmitting control information according to another embodiment of the present invention.

The configuration and overall operation of the apparatus for transmitting control information of FIG. 9 are the same as those of the apparatus of FIG. 8. However, in FIG. 9, the interleaver 908 and the physical channel mapper 912 perform a mapping operation on a modulation symbol based on the channel estimation capability for each time interval position performed by the physical channel mapper 808 of FIG. 8. That is, the interleaver 908 receives the interleaving rule of the modulation symbol based on the channel estimation capability according to the time interval position from the controller 910, and mixes the order of the modulation symbols input from the modulator 906 based on the interleaving rule. 912 sequentially maps the interleaved modulation symbols to PUCCH. Other configurations are the same as those described with reference to FIG. 8 and will not be described herein any further.

10 is a block diagram of an apparatus for receiving control information according to an embodiment of the present invention.

Referring to FIG. 10, a receiver receives a predetermined signal from a receiver 1010, extracts a signal mapped to the PUCCH from a received signal received from the receiver 1010 in a physical channel demapper 1000, and then a channel. The estimation / compensator 1001 performs channel estimation on the pilot symbols of the extracted PUCCH signal to perform channel compensation on the received PUCCH signal. The deinterleaver 1002 rearranges the channel-compensated signal by applying a deinterleaving rule or a demapping rule provided from the controller 1008. The deinterleaving rule or demapping rule is a rule corresponding to an interleaving rule or a physical channel mapping rule in a transmitter, and serves to reduce the order of signals in an original order. The rearranged signal is demodulated by the demodulator 1004 and then decoded by the decoder 1006 to correspond to the channel encoder of the transmitter. Since the first embodiment is a case where the control information is block coded (20, 5) having the UEP characteristic, the decoder 1006 performs a decoding operation of the (20, 5) block coding having the UEP characteristic. The decoder 1006 receives information related to decoding of a signal to be decoded, such as a decoding scheme, a code rate, and a UEP degree, from the controller 1008. From the decoded result, the receiver may obtain control information transmitted by the transmitter.

On the other hand, even when a general channel coding method having no UEP characteristics is applied, it is possible to obtain an effect of increasing reception reliability of a significant bit by applying the symbol mapping method or the interleaving method based on the channel estimation capability of each time interval location. . In this case, however, the increase of the reception reliability increased for the critical bit may be smaller than when the channel coding method having the UEP characteristic and the symbol mapping method or the interleaving method based on the channel estimation capability for each time interval location are used together.

Second Embodiment

Channel estimation performance is affected by the channel estimation algorithm implemented in the receiver, the rate of change of the wireless channel environment, the structure of the pilot symbol, and the like. In general, the channel estimation performance of the pilot symbol periphery is relatively good, but there may be other tendencies. For example, when the radio channel environment is hardly changed, there may be a case where the channel estimation performance is excellent through channel estimation through combining at a center point of two pilot symbols from the received signal-to-noise ratio of pilot symbols. Accordingly, the second embodiment changes some of the symbol mapping method or the interleaving method based on the channel estimation capability for each time interval position in the operation of the first embodiment, and performs some specific control to increase the reception symbol or the reception reliability. A modulation symbol containing information about the information bits is mapped to the center point of two pilot symbols in the slot.

In the second embodiment, an example of transmitting control information consisting of 5 bits by block coding (20, 5) to PUCCH (Physical Uplink Control Channel), which is a physical channel for transmitting the control information, is transmitted. It demonstrates with reference.

FIG. 11 is a conceptual diagram illustrating a process up to mapping to a physical channel for transmitting control information according to the second embodiment of the present invention.

The (20, 5) block coding has a feature of having a relatively high error correction capability for the MSB 1 bit 1108 of the input control information, and the basis sequence is shown in Table 1 above. Same as one. The control information is control information consisting of a plurality of bits, for example, CQI information for feeding back a channel state, feedback information required for operating multiple input / output antennas, or ACK / NACK feedback which is a response signal for the CQI information and received data. It may be a combination of information, or a combination of the control information. When the control information is composed of a combination of CQI information and ACK / NACK feedback information, since high reception reliability is generally required for the ACK / NACK feedback information, the ACK / NACK is configured to be mapped to the MSB.

The encoding process of reference numeral 1102 shows that the control information consisting of the 5 bits is encoded by applying the base code strings shown in Table 1 to a (0) to a (4). Accordingly, when the encoding process 1102 is performed, a total of 20 bits of encoded bits b (0) to b (19) are generated. Among the encoded bits, b (15) to b (19) 1110 show an additional error correction capability for a (4) by indicating a result of being repeated five times for a (4), which is an MSB of input control information. to provide.

Subsequently, in the generation process 1104 of the modulation symbol, the coded bit is generated according to a modulation scheme determined by a predetermined or predetermined rule. For example, when the QPSK modulation scheme is applied, one modulation symbol is generated from two consecutively coded bits, thereby generating a total of 10 modulation symbols m (0) to m (9). Accordingly, modulation symbols m (7), m (8), and m (9) 1112 are code bits b (15) to b (19) () which provide additional error correction capability for the MSB a (4). 1110).

In the physical channel mapping process 1106, the modulation symbol is mapped to the PUCCH. When the modulation symbol is mapped to the PUCCH as described above, the modulation symbols m (7), m (8), and m (9), which contain information on the MSB a (4), are relatively superior in channel estimation capability. By mapping to, the reception reliability for a (4) is further increased.

If the structure of the PUCCH to which the control information is mapped is a structure in which two pilot symbols exist in one slot and thus there are four pilot symbols 1116, 1124, 1130, and 1138 in one subframe, channel estimation is performed for each slot. In this case, the channel estimation capability tends to be relatively good at the position between two pilot symbols in each slot (720, 734) in terms of the received signal-to-noise ratio of the pilot symbol. Therefore, after first mapping a modulation symbol including information about a modulation symbol to increase reception reliability or some specific control information bits to increase reception reliability to the positions of the reference numerals 720 and 734, the remaining modulation symbols A modulation symbol including information about a modulation symbol for increasing reception reliability or some specific control information bits for improving reception reliability is mapped to a position other than the mapped position. In the example of FIG. 11, modulation symbols m (8) are mapped to s (2) 1120 and m (9) to s (7) 1134, respectively, and the remaining modulation symbols m (0) to m (7) are mapped. Indicates that m (8) and m (9) are sequentially mapped to unmapped positions. In the example of FIG. 11, the modulation symbol m (7) includes only part of information about the encoded bits of a (4) for relatively high reception reliability and has a relatively good channel estimation capability in the subframe. Since the point is limited to two places, the mapping priority is lower than that of m (8) or m (9).

More generally, the number of points where the channel estimation capability is relatively excellent is x during the time interval in which the control information is transmitted, and information on modulation symbols for increasing reception reliability or some specific control information bits for increasing reception reliability. When the number of modulation symbols including y is y, the total number of modulation symbols is z;

1) If x = y,

One-to-one mapping the y modulation symbols to the x different positions, respectively.

map z-y modulation symbols to positions where the y modulation symbols are not mapped, respectively.

In addition, z-y modulation symbols mapped as described above may be mixed for randomization. That is, the mapped z-y modulation symbols may be interleaved.

2) If x <y

Select x modulation symbols from the y modulation symbols and map them one-to-one to the x different positions.

map z-x modulation symbols to positions where the x modulation symbols are not mapped, respectively.

In addition, z-x modulation symbols mapped as described above may be mixed for randomization. That is, the mapped z-x modulation symbols may be interleaved.

3) If x> y,

Select and map some of the y modulation symbols from the x different positions, respectively. The y positions selected from the x different positions are dropped as much as possible, so that the mapped modulation symbols can be compensated with the remaining symbols even if some channel environment is suddenly bad.

map z-y modulation symbols to positions where the y modulation symbols are not mapped, respectively.

In addition, z-y modulation symbols mapped as described above may be mixed for randomization.

The time period in which the control information is transmitted is generally one subframe, and may be composed of a plurality of subframes for transmitting a large amount of control information. The mapping operation may be implemented as an interleaving operation having the same effect.

The transmission and reception apparatus of the second embodiment follows the description of FIGS. 8, 9, and 10 of the first embodiment, respectively. However, the symbol mapping method or the interleaving method based on the channel estimation capability of each time interval location includes a modulation symbol including information on a modulation symbol for improving reception reliability or some specific control information bits for improving reception reliability in a slot. Map to the center of the two pilot symbols.

On the other hand, even when a general channel coding method having no UEP characteristics is applied, it is possible to obtain an effect of increasing reception reliability of a significant bit by applying the symbol mapping method or the interleaving method based on the channel estimation capability of each time interval position. . In this case, however, the increase of the reception reliability increased for the significant bits may be smaller than when the channel coding method having the UEP characteristic and the symbol mapping method or the interleaving method based on the channel estimation capability for each time interval location are applied together.

In the above-described first and second embodiments, a channel encoding method (hereinafter, referred to as 'method 1') having a UEP characteristic and a symbol mapping method or interleaving method (hereinafter, referred to as 'method 2') based on channel estimation capability for each time interval location are provided. When applied together, it has been described that the respective methods are overlapped with respect to a specific bit for enhancing reception reliability among control information to be transmitted. However, a channel encoding method having a UEP characteristic may configure a bit for increasing reception reliability and a bit for improving reception reliability using a symbol mapping method or an interleaving method based on channel estimation capability for each time interval position. That is, the former has the effect of increasing the reception reliability over 'A' and 'Method 2' for A which is a bit or a set of bits in the control information, and the latter is B which is a bit or a set of bits in the control information. It is possible to increase the reception reliability with respect to 'Method 1', and to increase the reception reliability with respect to C, which is a bit or a set of bits, which is different from B which is a set of bits or bits. Therefore, in the latter case, an increase in reception reliability for B, which is a bit or a set of bits, may be different from an increase in reception reliability for C, which is a bit or a set of bits.

1 is a diagram illustrating a transmission structure of a PUCCH, which is a physical channel for transmitting control information in uplink in a current 3GPP LTE system;

2 is a conceptual diagram illustrating a process of mapping control information to a physical channel according to the present invention;

3 and 4 are flowcharts illustrating operations when transmitting control information according to an embodiment of the present invention;

5 and 6 are flowcharts illustrating operations when receiving control information according to an embodiment of the present invention;

7 is a conceptual diagram illustrating a process of mapping control information to a physical channel according to the first embodiment of the present invention;

8 is a block diagram of an apparatus for transmitting control information according to an embodiment of the present invention;

9 is a block diagram of an apparatus for transmitting control information according to another embodiment of the present invention;

10 is a block diagram of an apparatus for receiving control information according to an embodiment of the present invention;

11 is a conceptual diagram illustrating a process up to mapping to a physical channel for transmitting control information according to the second embodiment of the present invention.

Claims (4)

In the method of transmitting reverse control information in a mobile communication system, Encoding control information according to an uneven error protection method; Modulating the encoded symbols; And transmitting the modulated symbols to physical channels based on channel estimation capability to transmit the modulated symbols. In the reverse control information transmission apparatus in a mobile communication system, Encoding the transmitted information according to the unequal error protection method, A modulator for modulating the encoded symbols; A control unit which controls to map the modulated symbols to physical channels based on channel estimation capability; And a mapper for mapping the symbols modulated by the control of the controller. In the method of receiving reverse control information in a mobile communication system, A demapping process of separating the control channel signal from the received physical channel, An estimation and compensation process of performing compensation through channel estimation from the separated signal; Performing deinterleaving on the estimated and compensated signals in response to an interleaving scheme determined based on channel estimation capability; Demodulating the deinterleaved signal; And extracting control information by decoding the demodulated signal. An apparatus for receiving reverse control information in a mobile communication system, A demapper for separating a control channel signal from a received physical channel; An estimator and compensator for performing compensation through channel estimation from the separated signal; A deinterleaver for deinterleaving the estimated and compensated signals; A demodulator for demodulating the deinterleaved signal; A decoder which decodes the demodulated signal and extracts control information; And a control unit for controlling deinterleaving corresponding to the interleaving scheme determined based on the channel estimation capability.

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