KR101785609B1 - Techniques for cyclic redundancy check encoding in communication system - Google Patents

Abstract

A method for generating a Cyclic Redundancy Check (CRC) encoded message in a communication system includes the steps of generating the message, generating a first CRC for the message, Generating a CRC by scrambling the first CRC by a first bit permutation of the message; and scrambling the second CRC by a second bit permutation of the message. An apparatus for generating a cyclic redundancy check (CRC) encoded message in a communication system includes: a message generator for generating the message; and a second CRC generator for generating a first CRC for the message, And a second CRC encoder for generating a second CRC for the message and scrambling the second CRC by a second bit permutation of the message.

Description

TECHNICAL FIELD [0001] The present invention relates to a technique for a Cyclic Redundancy Check Coding

The present invention relates to a communication system, and more particularly, to an apparatus and method for cyclic redundancy check (CRC) encoding in a communication system.

The Cyclic Redundancy Check (CRC) is a method for comparing the CRC code generated at the receiving end and the CRC code generated at the transmitting end to detect an error of the transmitted information, Method. (Hereinafter, referred to as "LTE-A system ") and a 3GPP LTE-A (hereinafter referred to as " LTE- ") Specifications. Although the use of CRC is useful for information conveyed in LTE systems and LTE-A systems, the CRC can also be useful for communication of control channel information.

An example of a control channel message of the LTE system and the LTE-A system is a physical downlink control channel (PDCCH), and the PDCCH carries scheduling assignments and other control information. In the LTE system or the LTE-A system, the PDCCH is transmitted from a base station and received by a user equipment (UE). The base station may be referred to as an evolved Node B (eNB). Hereinafter, for the sake of convenience of explanation, the present invention is characterized in that a UE to receive the PDCCH message is referred to as an " intended UE ", and a UE that does not wish to receive the PDCCH message is referred to as an " unintended UE " Quot;

In the LTE system and the LET-A system, the transmission by the eNB and the reception by the UE of the PDCCH message are as shown in FIG. 1 and FIG. 2, respectively.

1 shows a configuration of an eNB for transmitting a PDCCH message in an LTE system or an LTE-A system according to the related art.

1, the eNB for transmitting a PDCCH message in the LTE system or the LTE-A system includes CRC encoders 102-A and 102-B, Tail-Biting Convolution Code (TBCC) 104-A and 104-B, rate matchers 106-A and 106-B, a multiplexer / aggregator 108, a scrambler 110, (MIMO) transmission processing unit 114, a resource mapping unit 116, a multiplexing unit 118, and an IFFT (Inverse Fast Fourier Transform) operation unit 120 .

The CRC encoder 102-A encodes a message A, which is a PDCCH message, for error detection. The message A, which is the PDCCH message, is generated by a PDCCH message generator (not shown). The CRC field of the CRC-encoded message is scrambled by the UE identifier of the target UE. In an LTE system or an LTE-A system, the UE identifier may be referred to as a Radio Network Temporary Identifier (RNTI). In an LTE system or an LTE-A system, there are various forms of the RNTI. For example, there are C-RNTI (Cell-RNTI) and RA-RNTI (Random Access-RNTI). The purpose of scrambling the CRC field with the UE ID is to allow only the target UE to detect the PDCCH message without errors and to be recognized as an erroneous message to other UEs that are non-target UEs.

The TBCC coder 104-A encodes a CRC-encoded message at a 1/3 TBCC coding rate. The code rate addition unit 106-A selects a plurality of coded bits from the coded bits for the message generated by the TBCC coder 104-A. The code rate addition unit 106-A is configured to match the number of transmission encoded bits of the PDCCH message with the amount of resources allocated for transmission of the PDCCH message.

The CRC encoder 102-B, the TBCC encoder 104-B and the code rate adder 106-B transmit the CRC encoder 102-A, the TBCC encoder 104- A), and performs the same operation as the operation performed on the message A by the code rate addition unit 106-A.

A plurality of PDCCH messages such as the message A and the message B may be transmitted through one Transmission Time Interval (TTI). The plurality of PDCCH messages transmitted through one TTI may be a destination of one or a plurality of UEs. In an LTE system or an LTE-A system, one TTI corresponds to one subframe, and the subframe has a time length of 1 ms. The coded bits generated from the plurality of PDCCH messages are multiplexed by the multiplexing and collecting unit 108 and scrambled by the scrambler 110 according to a cell-specific scrambling sequence, Modulated by a modulator 112 according to a Quadrature Phase Shift Keying (QPSK) modulation scheme.

When multiple antennas are employed, the MIMO transmission processing unit 114 performs MIMO processing on the modulation symbols output from the modulation unit 112. [ For example, in an LTE system, in the case of an eNB having two transmission antennas or four transmission antennas, a space-frequency block coding (SFBC) scheme or a frequency-switched transmit diversity (SFBC-FSTD) scheme is applied to PDCCH modulation symbols Can be applied.

After the MIMO process, a stream of modulation symbols is generated for each transmit antenna or each antenna port. In accordance with additional interleaving, the modulation symbols are modulated by the resource mapping unit 116 into an RE (Resource) symbol on a time-frequency grid of a subframe including a plurality of Orthogonal Frequency Division Multiplexing (OFDM) Element). ≪ / RTI > The multiplexing unit 118 multiplexes signals output from the resource mapping unit 116 and provides the multiplexed signals to the IFFT operation unit 120. The IFFT operation unit 120 performs an IFFT operation on the signal output from the multiplexing unit 118 and outputs a transmission signal.

The eNB transmits a plurality of PDCCHs by multiplexing a plurality of PDCCHs and mapping modulation symbols for the plurality of PDCCH messages to different time-frequency resources. In order to achieve sufficient performance of the PDCCH, PDCCH messages may be transmitted with different message sizes and different amounts of resources so as to accommodate different PDCCH message transmission requests to UEs having different channel conditions. It may be inefficient to signal the transmission format required for each PDCCH corresponding to at least one target UE. Therefore, in the LTE system or the LTE-A system, only the total amount of resources allocated for the PDCCH is signaled via the Physical Control Format Indicator Channel (PCFICH). As described below, the UEs employ a blind decoding scheme to detect the PDCCH message.

2 shows a configuration of a UE for receiving a PDCCH message in an LTE system or an LTE-A system according to the prior art.

2, the UE for receiving the PDCCH message in the LTE system or the LTE-A system includes CRC decoders 202-1 to 202-K, TBCC decoders 204-1 to 204- -K, rate de-matters 206-1 through 206-K, a demultiplexer and a de-multiplexer / de-aggregator 208, a descrambler 210 A demodulator 212, a MIMO reception processing unit 214, a resource de-mapper 216, a de-multiplexer and equalizer 218, an FFT Fourier transform) operation unit 220. [

The FFT operation unit 220 performs an FFT operation on the received signal. The demultiplexing and equalizing unit 218 demultiplexes the received signal output from the FFT calculator 220 and equalizes the received signal. The resource demapping unit 216 extracts symbols from REs on a time-frequency lattice of a subframe including a plurality of OFDM symbols. The MIMO reception processing unit 214 performs MIMO reception processing on the extracted symbols, and the symbols are demodulated by the demodulation unit 212 and descrambled by the descrambler 210. The demultiplexing and despreading unit 208 demultiplexes and demulculates the signals output from the demodulating unit 212 and demultiplexes and demulculates the signals output from the code rate demodulating units 206-1 to 206- . The code rate antorecting units 206-1 to 206-K antitheticalize the code rate of the signals output from the demultiplexing and despreading unit 208 and output the demodulated signal to the TBCC decoders 204-1 to 204- 204-K. The TBCC decoders 204-1 through 204-K perform TBCC decoding on the signals provided from the code rate inverse correcting units 206-1 through 206-K, and output the TBCC decoded signals to the CRC decoders 202- 1 to 202-K, respectively. The CRC decoders 202-1 to 202-K perform CRC decoding on the signals provided from the TBCC decoders 204-1 to 204-K and perform blind decoding of hypotheses 1 to K Output. Operations performed from the demultiplexing and despreading unit 208 to the CRC decoders 202-1 through 202-K constitute receiving-end blind decoding for PDCCH messages.

The number of opportunities to transmit the PDCCH is limited and the number of possible PDCCH message formats (e.g., Downlink Control Information (DCI) format) is also limited. In addition, to limit the number of blind decodings that the UE will perform, the number of opportunities to send PDCCH messages to a particular UE and the DCI format that a particular UE needs to detect is further limited. The UE assumes a possible DCI format at a possible resource location and attempts to decode the PDCCH message. If the UE successfully decodes the message, the CRC for the message passes CRC error detection. At this time, if the PDCCH message is a destination of the UE, the CRC scrambling sequence coincides with the RNTI of the UE. The UE attempts to decode the PDCCH assuming all combinations of DCI format and resource location that the UE can take. This allows the eNB to exclude additional signaling for the DCI format and message location corresponding to the UE.

The multiplexing and mapping of the PDCCH message to the time-frequency resource in the LTE system or the LTE-A system is as shown in Fig.

3 shows multiplexing and mapping of PDCCH messages in an LTE system or an LTE-A system according to the prior art.

Referring to FIG. 3, modulation symbol quadruplets are configured according to encoding, code rate matching, scrambling, modulation, and MIMO processing. The modulation symbol quadro frit means a bundle of four modulation seeds. The modulation symbol quadro frets are interleaved and then mapped to Resource Element Groups (REGs). All REGs contain four resource elements for data transmission. Thus, all REGs can carry a modulation symbol quadroplet.

The PDCCH message is transmitted through the aggregation of at least one continuous Control Channel Element (CCE). One CCE corresponds to nine resource element groups (REG). In other words, every CCE corresponds to nine modulation symbol quadro frites, i.e., 36 modulation symbols. For example, as shown in FIG. 3, the first PDCCH is transmitted through nine resource element groups as 36 modulation symbols s ₀ through s ₃₅ . The nine resource element groups constitute a first CCE. The second PDCCH is transmitted through nine resource element groups as ₃₆ modulation symbols s ₃₆ through s ₇₁ . The nine resource element groups constitute a second CCE.

In an LTE system or an LTE-A system, the number of REGs not allocated for PCFICH or PHICH (Physical Hybrid Automatic Repeat-ReQuest Indicator Channel) is N _REG . The number of CCEs valid in the LTE system or the LTE-A system ranges from 0 to N _CCE -1. Here, N _CCE is N _REG / 9. The PDCCH supports a plurality of formats. For example, the formats are shown in Table 1 below. A PDCCH message composed of n consecutive CCEs may be initiated from a CCE where the result of i mod n is zero. Here, i means a CCE number. A plurality of PDCCH messages may be transmitted in one subframe.

PDCCH format Number of CCEs REG count Number of PDCCH bits 0 One 9 72 One 2 18 144 2 4 36 288 3 8 72 576

The PDCCH message may be transmitted using one, two, four or eight CCEs. The PDCCH message may be referred to as DCI. As described above, the message can be started from a CCE in which the result value of i mod n (i is a CCE number) is 0, which is composed of n consecutive CCEs. As a result, the CCE aggregation shows a tree structure, for example, as shown in FIG. 4 below.

4 shows a tree structure of CCE aggregation in an LTE system or LTE-A system according to the prior art.

The LTE system includes a mechanism for preventing an error event of PDCCH message detection. For example, the CRC scrambling of the PDCCH message using the RNTI of the target UE is performed only when the target UE only detects the PDCCH message and successfully passes the CRC error check, other UEs fail to detect the PDCCH message, It can not pass the CRC error check. In addition, in order to reduce the possibility of CRC failure detection (e.g., an error event that has passed CRC error detection for erroneous PDCCH detection), measurements are made to limit the number of blind decodings. For example, a PDCCH composed of n consecutive CCEs may start with a CCE where the result of i mod n (where i is a CCE number) is zero. In summary, the PDCCH is designed such that the target UE is capable of blind detection with a high probability.

In the LTE-A system, carrier aggregation and cross-carrier scheduling are supported. When the carrier aggregation is implemented in the LTE-A system, each carrier is referred to as a CC (Component Carrier). For a PDCCH message belonging to a downlink CC for scheduling a downlink transmission in another downlink CC or for scheduling an uplink transmission in an uplink CC paired with the other downlink CC, Carrier Indication Field (CIF) is required for the PDCCH message for the purpose of carrier scheduling.

In addition, the UE monitors a search space for a PDCCH message targeted at a particular CC. Search spaces for different CCs are different. When the eNB transmits the PDCCH to the UE, the eNB transmits the PDCCH through one or several resources in the search space corresponding to the target CC. If the resource used to transmit the PDCCH message is located in a part of the search space for the CC that does not overlap with the search space of another CC, the CIF field of the PDCCH message is redundant. This is because the CC information is already implied based on the resources used to transmit the PDCCH message. Such scenarios may occur frequently. In other words, at times, the CIF is unnecessary. On the other hand, the PDCCH failure detection probability raises concerns about the reliability and operational efficiency of the LTE system or the LTE-A system. Thus, as with other control channel messages and payload data, there is a benefit to improve failure detection capabilities for PDCCH messages.

Therefore, techniques for improving the failure detection capability of CRC encoded information should be presented.

It is therefore an object of the present invention to provide an apparatus and method for CRC in a communication system.

It is another object of the present invention to provide an apparatus and method for improving the failure detection capability of CRC encoded information such as payload information and control channel information in a communication system.

According to a first aspect of the present invention, there is provided a method for generating a Cyclic Redundancy Check (CRC) -coded message in a communication system, the method comprising: generating the message; Generating a first CRC for the message, generating a second CRC for the message, scrambling the first CRC by a first bit permutation of the message, And scrambling the second CRC by the second CRC.

According to a second aspect of the present invention, there is provided an apparatus for generating a cyclic redundancy check (CRC) -coded message in a communication system, the apparatus comprising: a message generator for generating the message; A first CRC encoder for generating a first CRC for the message and scrambling the first CRC by a first bit permutation of the message and a second CRC for generating a second CRC for the message, And a second CRC encoder for scrambling the second CRC.

Advantageously, the first CRC scrambles the message according to a first bit sequence and the second CRC scrambles the message according to the second bit permutation, thereby improving the failure detection capability of the CRC encoded information .

1 shows a configuration of an eNB for transmitting a PDCCH message in an LTE system or an LTE-A system according to the related art,
2 is a diagram illustrating a configuration of a UE for receiving a PDCCH message in an LTE system or an LTE-A system according to the prior art;
3 is a diagram illustrating multiplexing and mapping of PDCCH messages in an LTE system or an LTE-A system according to the prior art;
4 is a diagram showing a tree structure of CCE aggregation in an LTE system or an LTE-A system according to the prior art,
5 is a diagram illustrating a procedure for generating and scrambling two CRCs for a PDCCH message in a communication system according to an embodiment of the present invention;
6 is a diagram illustrating an example of generation and scrambling for two CRCs for a PDCCH message in a communication system according to an embodiment of the present invention;
7 illustrates a procedure for generating and scrambling two CRCs for a PDCCH message in a communication system according to another embodiment of the present invention;
8 is a diagram illustrating an example of generation and scrambling for two CRCs for a PDCCH message in a communication system according to another embodiment of the present invention,
9 is a block diagram of an apparatus for generating a CRC encoded control channel message in a communication system according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

The present invention is described below with reference to a CRC encoding technique in a communication system. Hereinafter, the present invention uses terminology and names defined in the Institute of Electrical and Electronic Engineers (IEEE) 802.16e, IEEE 802.16m, 3GPP LTE, and 3GPP LTE-A standards. However, it is to be understood that the invention is not to be limited by the terms and names above. Also, for convenience of explanation, the present invention will be described taking as an example a system based on the LTE or LTE-A standard.

Hereinafter, the present invention will be described taking the PDCCH of LTE-A as an example. Furthermore, the present invention will be described taking the CIF of the PDCCH of LET-A as an example. However, the present invention is applicable to other message fields of the LTE-A system or to other message fields of the packet, and further applicable to other communication systems. For example, the present invention can be applied to communication of payload data.

Hereinafter, terms such as "transmission terminal "," base station ", "eNB" Similarly, terms such as "receiving end "," UE ", and the like are used interchangeably to indicate the same object.

The present invention can be implemented in an eNB as shown in FIG. 1 and a UE as shown in FIG.

According to an embodiment of the present invention, a first CRC is generated for the message and scrambled according to a first bit sequence. A second CRC is generated for the message and scrambled according to the second bit permutation. A method of CRC encoding and scrambling according to an embodiment of the present invention will now be described with reference to FIG.

5 illustrates a procedure for generating and scrambling two CRCs for a PDCCH message in a communication system according to an embodiment of the present invention.

Referring to FIG. 5, in step 501, a message is generated. In step 503, a first CRC and a second CRC for the message are generated. In step 505, the first CRC and the second CRC are scrambled using a first bit permutation of the message and a second bit permutation of the message, respectively. If the message is a control channel message such as a PDCCH, the first bit permutation of the PDCCH message may be a CIF, and the first bit permutation of the PDCCH message may be a C-RNTI. For example, the generation and scrambling of the first CRC and the second CRC for the PDCCH may be as shown in FIG. 6 below.

6 illustrates an example of generation and scrambling for two CRCs for a PDCCH message in a communication system according to an embodiment of the present invention.

과 같은 다항식(polynomial) 형태로 표현될 수 있다.Referring to FIG. 6, the bits of the PDCCH message 600 are m ₀ . m ₁ , ... , m _{N -1} . Here, N is the total number of bits of the PDCCH message 600. The PDCCH message 600 includes

And can be expressed in a polynomial form.

와 같고, 제2 CRC(620)의 생성 다항식은

와 같다.The generator polynomial of the first CRC 610 is

And the generator polynomial of the second CRC 620 is

.

와 같다. 상기 제1 CRC(610)는

을 만족하도록 생성된다. 다시 말해,

가 성립한다.The first CRC 610

. The first CRC 610

. In other words,

.

와 같다. 상기 제2 CRC(620)는

를 만족하도록 생성된다. 다시 말해,

가 성립한다.The second CRC 620

. The second CRC 620

. In other words,

.

The first CRC 610 and the second CRC 620 are scrambled according to a first bit permutation and a second bit permutation, respectively.

가 된다. 상기 스크램블링된 CRC 필드들(612 및 622)은 상기 PDCCH 메시지(600)의 종단에 첨부될 수 있다. 이 경우, 비트 순열은

와 같다.The scrambled CRC fields 612 and 622 are attached to the payload of the PDCCH message 600. As a result, the bit sequence is

. The scrambled CRC fields 612 and 622 may be attached to the end of the PDCCH message 600. In this case, the bit permutation is

.

The first CRC 610 and the second CRC 620 are attached to the PDCCH message 600 after being scrambled. However, according to another embodiment of the present invention, the first CRC 610 and the second CRC 620 may be attached to the PDCCH message 600 and then scrambled.

는 CIF일 수 있다. 제2비트 순열

는 C-RNTI일 수 있다. 상기 CIF의 길이 및 상기 제1 CRC(610)의 길이는 3 비트일 수 있다. 상기 C-RNTI의 길이 및 상기 제2 CRC(620)의 길이는 16 비트일 수 있다. 상기 제1 CRC(610) 및 상기 제2 CRC(620) 모두는 상기 PDCCH 메시지(600)의 페이로드로부터 생성될 수 있다. 이러한 방식의 장점은, LTE 시스템에 따른 16 비트 CRC 및 상기 16 비트 C-RNTI를 이용한 16 비트 CRC의 스크램블링 절차를 LTE-A 시스템에서 재사용할 수 있다는 것이다. 나아가, CIF가 다른 메커니즘으로부터 가정되거나 유도될 수 있는 경우, 3 비트 CRC는 상기 PDCCH 메시지(600)의 실패 검출 확률을 줄일 수 있다.The first bit permutation

May be CIF. The second bit permutation

May be a C-RNTI. The length of the CIF and the length of the first CRC 610 may be three bits. The length of the C-RNTI and the length of the second CRC 620 may be 16 bits. Both the first CRC 610 and the second CRC 620 may be generated from the payload of the PDCCH message 600. The advantage of this scheme is that the 16-bit CRC according to the LTE system and the 16-bit CRC scrambling procedure using the 16-bit C-RNTI can be reused in the LTE-A system. Further, if the CIF can be assumed or derived from other mechanisms, a 3-bit CRC may reduce the probability of failure detection of the PDCCH message 600.

According to an embodiment of the present invention, a first CRC is generated for the message and a first bit permutation is used for scrambling the first CRC. A second CRC is generated for the message comprising the attached scrambled first CRC and a second bit permutation is used for scrambling the attached second CRC. The CRC encoding and scrambling procedure according to an embodiment of the present invention will now be described with reference to FIG.

FIG. 7 illustrates a method for generating and scrambling two CRCs for a message according to another embodiment of the present invention.

Referring to FIG. 7, in step 701, a message is generated. In step 703, a first CRC for the message is generated. In step 705, the first CRC is scrambled using the first bit permutation of the message. In step 707, a second CRC for the message including the scrambled first CRC is generated. In step 709, a second CRC for the message is scrambled. When the message is a Control Channel message such as a PDCCH message, the first bit permutation of the PDCCH message is CIF and the second bit permutation of the PDCCH message is a C-RNTI. An example of generating and scrambling the first and second CRC of the PDCCH message will be described with reference to FIG.

FIG. 8 shows an example of generating and scrambling two CRCs for a PDCCH message according to an embodiment of the present invention.

으로 다항식 형태로 표현된다.Referring to FIG. 8, the bits of the PDCCH message 800 are m ₀ . m ₁ , ... , m _{N -1} . Here, N is the number of bits of the PDCCH message 800. The PDCCH message 800 may also include

As a polynomial expression.

으로 나타내고, 제2 CRC(820)의 생성다항식은

으로 나타낸다.The generator polynomial of the first CRC 810 is

And the generator polynomial of the second CRC 820 is represented by

Respectively.

으로 나타낸다. 상기 제1 CRC(810)는

으로 생성된다. 다시 말해,

와 같다.The first CRC 810 includes

Respectively. The first CRC 810 includes

. In other words,

.

를 포함하는 스크램블링 제1 CRC 필드(812)가 결정된다.The PDCCH message 800 to which the first CRC 810 is attached is scrambled by the first bit permutation. Bit permutation

The first scrambling CRC field 812 is determined.

While the first CRC 810 is illustrated as being scrambled attached to the payload of the PDCCH message 800, the first CRC 810 is scrambled as an alternative to the PDCCH message 800, Lt; / RTI > can be attached to the payload of the < / RTI >

으로 나타내다. 상기 제2 CRC(820)는

로 생성된다. 다시 말해,

와 같다.The second CRC 820

Respectively. The second CRC 820

. In other words,

.

를 포함하는 스크램블링 제2 CRC 필드(822)가 결정된다. 다른 대안으로, 상기 비트 순열은

으로 정의될 수 있다.The PDCCH message 800 to which the first CRC 810 and the second CRC 820 are attached is scrambled by the second bit permutation. Bit permutation

The second scrambling CRC field 822 is determined. Alternatively, the bit permutation may be

. ≪ / RTI >

While the second CRC 820 is shown scrambled to be attached to the payload of the PDCCH message 800, the second CRC 820 is scrambled as an alternative to the payload of the PDCCH message 800 May be attached to a payload.

The advantage of the CRC encoding and the scheme of embedding message fields is that a legacy 16-bit CRC can be reused in the second CRC 820. In addition, a 3-bit CRC (i.e., the first CRC 810) is introduced. The 3-bit CRC is scrambled by the 3-bit CIF. During blind detection on message detection or estimation for a PDCC message, the UE often knows or assumes a single CIF value or several CIF values. As a result, the 3-bit CRC scrambled by the CIF provides additional error detection capability for the remainder of the message field. In addition, since the second CRC 820 is generated from all message fields before processing the second CRC 820, the encoding scheme is used by the UEs that do not support the first CRC 810 (E.g., UEs configured to operate in accordance with LTE instead of LTE-A) use only the second CRC 820 and provide good backward compatibility with respect to following the LTE CRC decoding processor.

In the LTE system, a code block CRC for each code block and a transport block CRC for each transport block are provided to provide error detection capability to a transport block that is segmented into a plurality of code blocks Is used. However, since the two CRC generator polynomials and the transmission block CRC are not co-prime, the effect of error detection is reduced.

을 사용한다고 가정할 때, 상기 전송블록 CRC는 생성다항식

를 사용한다. 여기서,

는

와

사이 가장 큰 공통인수(common factor)이다.

과

는 서로소(co-prime)이다. 에러 메시지가 상기 코드블록 CRC 그리고 상기 전송블록 CRC 모두의 에러검출을 통과하도록 하기 위해서, 상기 에러메시지는

와

에 모두에 의해 둘로 나누어질 필요가 있으며, 이는

에 의해 둘로 나누어지는 것을 의미한다. 두 개의 CRC 생성다항식을 통과하는 에러메시지 개수를 최소화하기 위해, 가능한 크도록 다항식

의 차수(order)를 선호한다.

의 순서를

이라 가정할 때,

의 순서는

이고

의 ctmn는

이고,

의 차수는

이고 그리고

의 차수는

이다. 여기서,

그리고

와 같다.

의 차수는

이다. 그 결과,

와

사이의 가장 큰 공통인수의 차수가 최소화된다면,

의 차수는 최대화된다. 이는

와

가 서로 소일 때

의 차수가 최소화된다는 것을 의미이다.If the code block CRC is a generator polynomial

, The transport block CRC is generated by a generator polynomial < RTI ID = 0.0 >

Lt; / RTI > here,

The

Wow

Is the largest common factor between the two.

and

Are co-prime. In order for an error message to pass through error detection of both the code block CRC and the transport block CRC,

Wow

Need to be divided into two by all,

Quot; is divided by two. To minimize the number of error messages that pass through the two CRC generator polynomials,

Order.

The order of

Assuming that,

The order of

ego

Ctmn of

ego,

The order of

And

The order of

to be. here,

And

.

The order of

to be. As a result,

Wow

If the order of the greatest common argument between the two is minimized,

Is maximized. this is

Wow

When each other

Is minimized.

In an embodiment of the present invention, a first CRC is generated for a code block using a first generator polynomial, and a second CRC is generated for a transport block using a second generator polynomial that is prime with the first generator polynomial do. The code block may be a segment of the transport block or the transport block. The first CRC is a code block CRC, and the second CRC is a transport block CRC. The code block CRC is generated based on the bits in the code block. The transport block CRC is generated based on the bits in the transport block. And the calculation will also include the bits of the code block CRC.

으로 표현돤다. 상기 제1 CRC는

으로 표현되는 생성다항식을 사용할 수 있다. In an embodiment of the present invention a first CRC is generated for a message using a first generator polynomial and a second CRC is generated for the message using a second generator polynomial, 2 The generator polynomials are relatively small. The first CRC may be made by a first bit permutation and the second CRC by a second bit permutation. For example, the first bit permutation may be CIF and the second bit permutation may be a C-RNTI. The second CRC may use the 16-bit CRC generator polynomial from the LTE system,

. The first CRC

Can be used.

로 나타내지는 생성다항식을 사용할 수 있다.Here, in the first CRC generating polynomial, the second CRC generating polynomials are opposite to each other. In other words, these two CRC generator polynomials do not have a common polynomial factor (except for a trivial polynomial factor of 1). Alternatively, the first CRC

Lt; RTI ID = 0.0 > polynomial < / RTI >

으로 표현할 수 있다. 다른 대안으로, 상기 19비트 CRC 생성다항식은

으로 선택될 수 있다.
In an embodiment of the invention, the CRC is used for a message comprising a first region of the CRC scrambled by a first bit permutation and a second region of the CRC scrambled by a second bit permutation. For example, the first bit permutation may be a CIF number and the second bit permutation may be a C-RNTI. The length of the CIF is 3 bits. The length of the C-RNTI may be 16 bits. And the length of the CRC may be 19 bits. The 19-bit CRC generator polynomial may be obtained by multiplying a 16-bit generator polynomial with a 3-bit generator polynomial. For example, the selection of a 19-bit CRC generator polynomial

. Alternatively, the 19-bit CRC generator polynomial

. ≪ / RTI >

The structure of an apparatus for generating a CRC encoded control channel message will be described below with reference to FIG.

9 illustrates a structure of an apparatus for generating a CRC encoded message according to an embodiment of the present invention.

Referring to FIG. 9, the apparatus includes a message generator 902, a first CRC encoder 904, and a second CRC encoder 906. The device may include additional components. In addition, the functions of each control channel message generator 902, first CRC encoder 904, and second CRC encoder 906 may be performed by one or more components. Also, the functions of the message generator 902, the first CRC encoder 904, and the second CRC encoder 906 can be performed by one component. The device may be configured by an LTE or LTE-A system or by an eNB or UE of another communication system.

The control channel message generator 902 generates a message such as a PDCCH message. The first CRC encoder 904 performs the CRC encoding operations described with respect to the first CRC. For example, the first CRC encoder 904 generates a first CRC for the message and scrambles the first CRC by a first bit permutation of the message. The second CRC encoder 906 performs CRC encoding operations described with respect to the second CRC. For example, the second CRC encoder 906 generates a second CRC for the message and performs the first CRC scrambling with a second bit permutation of the PDCCH message.

The embodiment of the present invention is described as an embodiment, which encodes CIF and C-RNTI in PDCCH messages in the LTE-A system. However, at the level of those skilled in the art, the techniques described above may apply message fields other than CIF and C-RNTI in the control channel message. Moreover, at the level of those skilled in the art, the techniques of the present invention may be employed for any other transmitted information in any communication system type. Such implementations are contemplated within the scope of the present invention.

In addition, exemplary embodiments of the invention may include computer readable code on a computer readable medium. The computer readable medium may include any data storage means for storing data that can be read by the computer system. Examples of computer readable media include storage media such as magnetic storage media (ROM, floppy disks, hard disks, etc.), optical recording media (such as CD-ROM or DVD), and carrier waves (such as transmission over the Internet). In addition, the computer readable medium may be distributed over a network connected to the computer system, and may be stored and executed through a distribution method. Also, functional programs, codes, and code segments that perform the exemplary embodiments of the present invention may be understood by those of ordinary skill in the art to which the present invention pertains.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various modifications within the scope of the invention. Therefore, the scope of the present invention should not be limited by the illustrated embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

Claims (39)

A method for generating a Cyclic Redundancy Check (CRC) encoded message in a communication system,
Generating the message;
Generating a first CRC for the message;
Scrambling the first CRC by a first bit permutation of the message;
Generating a second CRC for the message;
Scrambling the second CRC by a second bit permutation of the message;
And attaching the scrambled first CRC and the scrambled second CRC to the message. The method according to claim 1,
Wherein the first CRC and the second CRC are generated independently. 3. The method of claim 2,
Wherein the first CRC and the second CRC are appended to the message before being scrambled. 3. The method of claim 2,
Wherein the first CRC and the second CRC are scrambled before being attached to the message. The method according to claim 1,
The generating of the second CRC comprises:
Attaching the first CRC to the message;
And generating the second CRC from a message comprising the first CRC. 6. The method of claim 5,
Wherein the first CRC is appended to the message before being scrambled. 6. The method of claim 5,
Wherein the first CRC is scrambled before being attached to the message. 6. The method of claim 5,
Wherein the second CRC is appended to the message before being scrambled. 6. The method of claim 5,
And wherein the second CRC is scrambled before being attached to the message. The method according to claim 1,
Wherein the message is a control channel message. 11. The method of claim 10,
Wherein the control channel message is a Physical Downlink Control Channel (PDCCH) message. 11. The method of claim 10,
Wherein the first bit permutation of the control channel message is a CIF (Carrier Indication Field) of the control channel message. 11. The method of claim 10,
Wherein the first bit permutation of the control channel message is a 3 bit permutation and the first CRC is a 3 bit CRC. 11. The method of claim 10,
Wherein the second bit permutation of the control channel message is a Cell-Radio Network Temporary Identifier (C-RNTI) of the control channel message. 11. The method of claim 10,
Wherein the second bit permutation of the control channel message is a 16-bit permutation and the second CRC is a 16-bit CRC. The method according to claim 1,
Wherein the communication system is a communication system based on one of a 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) and a 3GPP LTE-A (LTE-Advanced). The method according to claim 1,
Wherein the first CRC and the second CRC are generated using generator polynomials that are co-prime. The method according to claim 1,
Wherein the first CRC is a CRC for a code block of the message and the second CRC is a CRC for a transport block of the message. 19. The method of claim 18,
Wherein the first bit permutation comprises bits from the code block of the message and the second bit permutation comprises bits from the transport block of the message. An apparatus for generating a Cyclic Redundancy Check (CRC) encoded message in a communication system,
A message generator for generating a message,
A first CRC encoder for generating a first CRC for the message and scrambling the first CRC by a first bit permutation of the message and attaching the scrambled first CRC to the message;
And a second CRC encoder for generating a second CRC for the message and scrambling the second CRC by a second bit permutation of the message and appending the scrambled second CRC to the message. . 21. The method of claim 20,
Wherein generation of the first CRC by the first CRC encoder and generation of the second CRC by the second CRC encoder are independent. 22. The method of claim 21,
Wherein the first CRC encoder appends the first CRC to the message before being scrambled and the second CRC encoder appends the second CRC to the message before being scrambled. 22. The method of claim 21,
The first CRC encoder scrambles the first CRC before appending the first CRC to the message and the second CRC encoder scrambles the second CRC before attaching the second CRC to the message Characterized in that. 21. The method of claim 20,
And the second CRC encoder generates the second CRC for a message comprising the scrambled first CRC. 25. The method of claim 24,
Wherein the first CRC encoder attaches the first CRC to the message before scrambling the first CRC. 25. The method of claim 24,
Wherein the first CRC encoder scrambles the first CRC before attaching the first CRC to the message. 25. The method of claim 24,
And the second CRC encoder scrambles the second CRC before attaching the second CRC to the message. 25. The method of claim 24,
Wherein the second CRC encoder attaches the second CRC to the message before scrambling the second CRC into the message. 21. The method of claim 20,
Wherein the message is a control channel message. 30. The method of claim 29,
Wherein the control channel message is a Physical Downlink Control Channel (PDCCH) message. 30. The method of claim 29,
Wherein the first bit permutation of the control channel message is a CIF (Carrier Indication Field) of the control channel. 30. The method of claim 29,
Wherein the first bit permutation of the control channel message is a 3-bit permutation, and the first CRC is a 3-bit CRC. 30. The method of claim 29,
Wherein the second bit permutation of the control channel message is a Cell-Radio Network Temporary Identifier (C-RNTI) of the control channel message. 30. The method of claim 29,
Wherein the second bit permutation of the control channel message is a 16-bit permutation and the second CRC is a 16-bit CRC. 21. The method of claim 20,
Wherein the communication system is a communication system based on one of a 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) and a 3GPP LTE-A (LTE-Advanced). 21. The method of claim 20,
Wherein the first CRC encoder generates the first CRC and the second CRC encoder generates the second CRC using co-prime generator polynomials. 21. The method of claim 20,
Wherein the apparatus is included in at least one of an evolved Node B (eNB) or a User Equipment (UE). 21. The method of claim 20,
Wherein the first CRC is a CRC for a code block of the message and the second CRC is a CRC for a transport block of the message. 39. The method of claim 38,
Wherein the first bit permutation comprises bits from the code block of the message and the second bit permutation comprises bits from the transport block of the message.

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