# Patent

## Title
Apparatus and method for transmitting data using a CTC (Convolutional Turbo Code) encoder in a mobile communication system

## Abstract

Apparatus and method for transmitting data using a CTC (Convolutional Turbo Code) encoder in a mobile communication system. The data transmission method according to the present invention includes: a first encoding step of encoding input data bits inputted through two input terminals of the CTC encoder and outputting first encoding bits; a step of interleaving the input data bits by using four CTC interleaver parameters (P0, P1, P2, and P3) corresponding to the sizes of the input data bits; a second encoding step of encoding the interleaved data bits and outputting second encoding bits; and a step of selectively transmitting the input data bits, the first encoding bits, and the second encoding bits to a receiving side in accordance with a predetermined coding rate.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a 371 U.S. national stage application of International Application No. PCT/KR2009/003827, filed on Jul. 13, 2009, which claims priority to U.S. Provisional Application Ser. Nos. 61/154,747, filed on Feb. 23, 2009, 61/154,417, filed on Feb. 22, 2009, 61/122,413, filed on Dec. 15, 2008, and 61/080,274, filed on Jul. 13, 2008, the contents of which are incorporated by reference herein in their entirety.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and method for transmitting data, and more particularly, to an apparatus and method for a transmitting end to transmit data using a Convolutional Turbo Code (CTC) encoder in a mobile communication system.
2. Discussion of the Related Art
In a wireless communication system, portions of transmission data may sometimes be lost at once due to fading. If consecutive data bits are lost at once, this error cannot be recovered from even when a very excellent error correction code is used.
In a wireless communication system, the transmitting end transmits an encoded transmission data sequence after changing the order of the transmission data bits according to a specific pattern using a channel interleaving method rather than transmitting the data bits in an order in which the data bits are input. That is, a burst error that frequently occurs in a radio link can be changed to a random error using channel interleaving.
When error bits are sparsely present among encoded transmission data, the error bits may be corrected using an error correction code such as a convolutional code, a turbo code, or a Low Density Parity Check (LDPC) code.
Basically, turbo coding, which is a channel coding technology, is a scheme which connects convolutional codes through parallel concatenation. The Convolutional Turbo Code (CTC) is one of the channel codes used in mobile Internet services.
As is well known, a next-generation mobile communication system requires reliable transmission of multimedia data at a high speed and requires robust channel coding and an efficient modulation scheme in order to increase reliability of high-speed data transmission. Various coding schemes having specifications enabling high-speed data communication such as convolutional coding or turbo coding have been suggested and introduced in many countries. Such channel coding schemes exhibit better performance depending on an interleaver size or a corresponding data block size. Thus, intensive studies have been carried out on an interleaver that greatly affects turbo code performance.
CTC may support two data block size sets in the case of channel coding in a conventional Institute of Electrical and Electronics Engineers (IEEE) 802.16e system. One of the two data block size sets includes data block sizes of 48, 72, 96, 144, 192, 216, 240, 288, 360, 384, 432, and 480 and the other includes data block sizes of 48, 96, 144, 192, 288, 384, 480, 960, 1920, 2880, 3840, and 4800. However, even when the two data block size sets are combined, data block sizes at great intervals therebetween may be selected from the combined range of 48 to 4800.
Table 1 shows each data block size and values of corresponding CTC interleaver parameters P0, P1, P2, and P3 in the conventional IEEE 802.16e system.













TABLE 1






index
NEP
P0
P1
P2
P3






















1
48
5
0
0
0



2
72
11
18
0
18



3
96
13
24
0
24



4
144
11
6
0
6



5
192
7
48
24
72



6
240
13
60
0
60



7
288
17
74
72
2



8
360
11
90
0
90



9
384
11
96
48
144



10
432
13
108
0
108



11
480
13
120
60
180



12
960
53
62
12
2



13
1920
43
64
300
824



14
2880
43
720
360
540



15
3840
31
8
24
16



16
4800
53
66
24
2









Since a CTC encoder can only support data block sizes corresponding to the preset data block size sets, there is a need to use padding bits when an information block size is not included in the data block size sets. The number of padding bits is equal to the difference between the information block size and the smallest data block size in the set greater than the information block size. Thus, if granularity, which corresponds to the difference between two adjacent data block sizes in a data block size set, is increased in the data block size set, padding overhead is also increased.
The IEEE 802.16e system has great padding overhead since the CTC data block sizes have a great interval of granularity. Thus, although there is a need to define new CTC data block sizes, CTC data block sizes having better granularity have not yet been suggested in the IEEE 802.16m system.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a method for a transmitting end to transmit data using a Convolutional Turbo Code (CTC) encoder in a mobile communication system.
Another object of the present invention is to provide an apparatus for a transmitting end to transmit data using a Convolutional Turbo Code (CTC) encoder in a mobile communication system.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a method for a transmitting data using a Convolutional Turbo Code (CTC) encoder in a mobile communication system includes providing first encoded bits by encoding input data bits inputted to two input ports of the CTC encoder, interleaving the input data bits using 4 CTC interleaver parameters (P0, P1, P2, and P3) corresponding to a size of the input data bits, providing second encoded bits by encoding the interleaved input data bits, and selectively transmitting the input data bits, the first encoded bits, and the second encoded bits according to a predefined code rate, wherein the size of the input data bits is one of M predetermined data bit sizes, and wherein P0 is relative prime number with N which is 1⁄2 of the size of the input data bits, P1 is a multiple of 2 among natural numbers, P2 is a multiple of 4 among the natural numbers, and wherein P3 is a multiple of 2 among the natural numbers when (P1 modulo 4)=2, and P3 is a multiple of 4 among the natural numbers when (P1 modulo 4)=0.
In another aspect of the present invention, an apparatus for transmitting data using a Convolutional Turbo Code (CTC) encoder in a mobile communication system includes a first encoder for providing first encoded bits by encoding input data bits inputted to two input ports of the CTC encoder, a CTC interleaver for interleaving the input data bits using 4 CTC interleaver parameters (P0, P1, P2, and P3) corresponding to a size of the input data bits, a second encoder for providing second encoded bits by encoding the interleaved input data bits, and a transmission module for selectively transmitting the input data bits, the first encoded bits, and the second encoded bits according to a predefined code rate, wherein the size of the input data bits is one of M predetermined data bit sizes, and wherein P0 is relative prime number with N which is 1⁄2 of the size of the input data bits, P1 is a multiple of 2 among natural numbers, P2 is a multiple of 4 among the natural numbers, and wherein P3 is a multiple of 2 among the natural numbers when (P1 modulo 4)=2, and P3 is a multiple of 4 among the natural numbers when (P1 modulo 4)=0.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.



BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:
FIG. 1 illustrates simulation results of padding overhead according to CTC data block sizes suggested in Table 1.
FIG. 2 illustrates a preferred embodiment of a CTC encoder according to the present invention.
FIGS. 3 and 4 illustrate comparison between BLER performance of a CTC interleaver using data block sizes and CTC interleaver parameters suggested in the present invention and BLER performance of the conventional IEEE 802.16e CTC interleaver for each mother code rate.



DETAILED DESCRIPTION OF THE INVENTION
Reference will now be made in detail to the preferred embodiments of the present invention with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention, rather than to show the only embodiments that can be implemented according to the invention. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without such specific details. For example, although the following description will be given with reference to specific terms, the present invention is not necessarily limited to the specific terms and other terms may also be used to indicate the same meanings The same reference numbers will be used throughout this specification to refer to the same or like parts.
The expression “a portion includes a specific component” used throughout this specification indicates that the portion may also include other components, rather than including the specific component alone, unless explicitly stated otherwise.
Technologies described below can be used in various communication systems, which may provide various communication services such as voice and packet data services. The communication system technologies can be used in downlink or uplink. In the description of the present invention, the term “Base Station (BS)” may be replaced with another term such as “fixed station”, “Node B”, “eNode B (eNB)”, “access point”, or “ABS”. The “Mobile Station (MS)” may also be replaced with another term such as “User Equipment (UE)”, “Subscriber Station (SS)”, “Mobile Subscriber Station (MSS)”, “AMS”, or “mobile terminal”.
The term “transmitting end” refers to a node that transmits data or audio services and “receiving end” refers to a node that receives data or audio services. Thus, in uplink, the MS may be a transmitting end and the BS may be a receiving end. Similarly, in downlink, the MS may be a receiving end and the BS may be a transmitting end.
A Personal Digital Assistant (PDA), a cellular phone, a Personal Communication Service (PCS) phone, a Global System for Mobile (GSM) phone, a Wideband CDMA (WCDMA) phone, or a Mobile Broadband System (MBS) phone may be used as the MS in the present invention.
The embodiments of the present invention can be supported by standard documents of at least one of the Institute of Electrical and Electronics Engineers (IEEE) 802 system, the 3GPP system, the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) system, and the 3GPP2 system which are wireless access systems. That is, steps or portions that are not described in the embodiments of the present invention for the sake of clearly describing the spirit of the present invention can be supported by the standard documents. For all terms used in this disclosure, reference can be made to the standard documents. Especially, the embodiments of the present invention can be supported by P802.16-2004, P802.16e-2005, or P802.16Rev2 which are standard documents of the IEEE 802.16 system.
Specific terms used in the following description are provided for better understanding of the present invention and can be replaced with other terms without departing from the spirit of the present invention.
CTC data block size requirements in the IEEE 802.16m system are described as follows. First, data block sizes of the IEEE 802.16m system not only need to support data block sizes of the conventional IEEE 802.16e system but also need to be byte-aligned. The data block size is not a multiple of 7 to support a tail-biting encoding structure of CTC. It is preferable that the data block size set be designed to have better granularity to reduce padding overhead. In addition, the CTC data block size of the conventional IEEE 802.16e system needs to be supported by CTC of the IEEE 802.16m system. Each data block size needs to be increased to improve CTC performance and CTC interleaver parameters need to be optimized to achieve better CTC performance than in the IEEE 802.16e system. Rules of the CTC data block size together with granularity are described below.
1. Granularity for the data block sizes is increased taking into consideration padding overhead. First, it is preferable that a boundary data block size be defined so as to increase the granularity value. It is also preferable that granularity be defined taking into consideration the same padding parts of the boundary data block sizes.
2. It is preferable that the granularity value of the data block size is a multiple of 8 and byte-aligned.
3. As an exception to these rules, the granularity value may be twice as high as the desired granularity value in order to avoid data block sizes which are multiples of 7.
The CTC data block size rules are described below in more detail.
The boundary data block size used may be expressed as a power of 2 taking into consideration the minimum granularity value of 8. The boundary data block size may be 512, 1024, or 2048. The maximum padding bit portion may be fixed to 1.5625% of the entire boundary data block size.
For example, let us consider “40” and “48” as adjacent data block sizes. Here, the smaller data block size is 40 and the larger data block size is 48. A granularity value G may be defined by measuring the smaller data block size NEP among the two adjacent data block sizes. For example, G may be 8 when 40≦NEP≦512. On the other hand, G may be 16 when 512≦NEP≦1024, 32 when 1024≦NEP≦2048, and 64 when 2048≦NEP.
The greater data block size NEP+ among the two adjacent data block sizes may be defined as follows.
For example, NEP+=NEP+G when (NEP+G) %7≠0, otherwise NEP+=NEP+2G.
Here, %7 represents a modulo-7 operation.
According to these rules, the CTC data block size in the IEEE 802.16m system may be defined as shown in Table 1.









TABLE 2






Index
NEP


















1
40



2
48



3
64



4
72



5
80



6
88



7
96



8
104



9
120



10
128



11
136



12
144



13
152



14
160



15
176



16
184



17
192



18
200



19
208



20
216



21
232



22
240



23
248



24
256



25
264



26
272



27
288



28
296



29
304



30
312



31
320



32
328



33
344



34
352



35
360



36
368



37
376



38
384



39
400



40
408



41
416



42
424



43
432



44
440



45
456



46
464



47
472



48
480



49
488



50
496



51
512



52
528



53
544



54
576



55
592



56
608



57
624



58
640



59
656



60
688



61
704



62
720



63
736



64
752



65
768



66
800



67
816



68
832



69
848



70
864



71
880



72
912



73
928



74
944



75
960



76
976



77
992



78
1024



79
1056



80
1088



81
1152



82
1184



83
1216



84
1248



85
1280



86
1312



87
1376



88
1408



89
1440



90
1472



91
1504



92
1536



93
1600



94
1632



95
1664



96
1696



97
1728



98
1760



99
1824



100
1856



101
1888



102
1920



103
1952



104
1984



105
2048



106
2112



107
2176



108
2304



109
2368



110
2432



111
2496



112
2560



113
2624



114
2752



115
2816



116
2880



117
2944



118
3008



119
3072



120
3200



121
3264



122
3328



123
3392



124
3456



125
3520



126
3648



127
3712



128
3776



129
3840



130
3904



131
3968



132
4096



133
4160



134
4224



135
4288



136
4352



137
4416



138
4544



139
4608



140
4672



141
4736



142
4800









FIG. 1 illustrates simulation results of padding overhead according to CTC data block sizes suggested in Table 1.
Specifically, FIG. 1 illustrates results of comparison between padding overhead according to CTC data block sizes of the conventional IEEE 802.16e and padding overhead according to the CTC data block sizes suggested in the present invention. As can be seen from FIG. 1, the CTC data block sizes suggested in the present invention have excellent granularity and significantly reduce padding overhead, compared to the CTC data block sizes of the conventional IEEE 802.16e system.
FIG. 2 illustrates a preferred embodiment of a data transmission apparatus that transmits data using a Convolutional Turbo Code (CTC) encoder according to the present invention.
As shown in FIG. 2, the data transmission apparatus according to the present invention includes a constituent encoder 210, a CTC interleaver 220, and a transmission module (not shown).
When data bits (A, B) for coding are alternately input to the CTC encoder, the CTC encoder encodes the data bits (A, B) using a Dual Binary Circular Recursive Systematic Convolutional (CRSC) code. Data bits may be input to the CTC encoder on an NEP-bit basis (NEP=2×N bits) or on a N-bit-pair basis. Here, NEP indicates the CTC data block size (or CTC bit size).
The CTC encoder may perform encoding in two steps. In the first step, a switch provided in the CTC encoder is located to position 1 so that data bits (A, B) for coding is input to the constituent encoder 210 after an initialization process is performed through a circular operation. In the second step, the switch provided in the CTC encoder is switched to position 2 so that data bits (A, B) interleaved by the CTC interleaver 220 is input to the constituent encoder 210 after an initialization process is performed through a circular operation.
The CTC encoder may receive a signal from the outside or from an upper layer and may acquire NEP information having an encodable block size. Here, NEP=2×N, where N is the actual interleaver size and N is CTC data block size/2.
Data bits (A,B) is alternately input to the constituent encoder 210 receive for encoding. Specifically, the Most Significant Bit (MSB) of a data bit sequence may be input as the data bit A and a next bit may be input as the data bit B. This procedure may be repeated for the entire bit sequence. Here, the MSB of a value is a binary number that most significantly affects the magnitude of the value in a bit-based operation. That is, the MSB is the leftmost bit in a bit sequence representing the value.
The constituent encoder 210 may encode data bits (A, B) received through two input ports. Here, the constituent encoder 210 may perform encoding in two steps. The constituent encoder 210 may include a first encoder C1 that encodes data bits (A, B) received through the two input ports and a second encoder C2 that encodes data bits (A, B) received through the two input ports after being interleaved by the CTC interleaver 220. How data bits are interleaved through the CTC interleaver 220 is described below in more detail.
The CTC interleaver 220 may interleave data bits (A, B) received through the two input ports. The CTC interleaver 220 may receive the MSB of a data bit sequence as the data bit A and then receive a next bit thereof as the data bit B. This procedure may be repeated for the entire bit sequence input to the CTC interleaver 220.
The CTC interleaver 220 randomizes a data bit sequence inputted in units of a predetermined size to be used for improving codeword distance properties.
The CTC encoder may sequentially output data bits (A, B) inputted through the two input ports and data bit values encoded through the constituent encoder 210. For example, the output bits may be “ABY1Y2W1W2” in the case of code rate 1⁄3. The output bits may be “ABY1Y2” through removal of “W1” and “W2” in the case of code rate 1⁄3. Here, the output data bits (A, B) correspond to a systematic part and the data bits (Y1, W1) or (Y2, W2) output through the constituent encoder 210 corresponding to a parity part. The size of data bits output at the parity part may vary depending on code rate.
The transmission module (not shown) may selectively transmit data bits received through the two input ports, first encoded bits output from the first encoder C1, and second encoded bits output from the second encoder C2.
The operation of the CTC interleaver 220 is briefly described as follows.
The CTC interleaver 220 performs interleaving in two steps according to CTC interleaver parameters P0, P1, P2, and P3.
In the first step, the CTC interleaver 220 performs bit pair swapping of the data bits (A, B) to be coded. Specifically, first, the CTC interleaver 220 swaps the positions of each pair of bits such that if(jmod 2==0) let (B,A)=(A,B) for j=0, 1, 2, . . . , N−1. For example, let the input sequence be u0=[(A0, B0), (A1, B1), (A2, B2), . . . , (AN−1, BN−1)]. The CTC interleaver 220 performs bit pair swapping on each even symbol in the first step. That is, when u1 is the bit-pair-swapped sequence, u1=[(A0, B0), (B1, A1), (A2, B2), . . . , (BN−1, AN−1)]=[u1(0), u1(1), u1(2), . . . , u1(N−1)].
In the second step, the CTC interleaver 220 generates an interleaving address for swapped bit pair. The CTC interleaver 220 generates an interleaving address P(j) for a jth bit pair, completing the interleaving process. Here, P(j) may provide the address of the u1 sequence. That is, u2 (j)=u1(P(j)). As a result, u2=[(Bp(0), Ap(0), (Ap(1), Bp(1)), (Bp(2), Ap(2)), . . . , (Ap(N−1), Bp(N−1))]. This sequence u2 may be input to the second encoder.
The above process may be expressed as follows.
For j=0, 1, 2, . . . , N−1,
switch (j mod 4):
case 0: P(j)=(P0·j+1) mod N:
case 1: P(j)=(P0·j+1+N/2+P1) mod N:
case 2: P(j)=(P0·j+1+P2) mod N:
case 3: P(j)=(P0·j+1+N/2+P3) mod N:
As described above, the CTC interleaver 220 may perform interleaving by swapping a pair of bits of each even symbol in the first step and generating an interleaving address on the jth bit pair according to the above expression in the second step. The generated address may be associated with a data block index and the CTC interleaver 220 may perform interleaving using the associated data block index and 4 corresponding CTC interleaver parameters.
A method for optimizing the CTC interleaver 220 in the IEEE 802.16m system is described below. The CTC interleaver 220 may be designed and optimized according to the CTC data block sizes according to the present invention.
The CTC interleaver structure in the IEEE 802.16m system may be reused. The CTC interleaver 220 knows CTC interleaver parameters (P0, P1, P2, and P3) corresponding to each data block size. The method may be performed using the 4 CTC interleaver parameters and the data block size in the following manner (Here, N is data block size/2).
The CTC interleaver may be designed and optimized taking into consideration the two steps of interleaving described above. The method for optimally designing CTC interleaver parameters may include the following steps.
In the first step, a spatial distance is calculated using a parameter test set. The following parameter test set may be considered, taking into account the CTC interleaver structure. That is, four parameters P0, P1, P2, and P3 preferably have the following characteristics.
First, P0 is relatively prime to N.
P1 is a natural number, which is a multiple of 2, such that P1=0, 2, 4, . . . , N−2.
P2 is a natural number, which is a multiple of 4, such that P2=0, 4, 8, . . . , N−4.
P3 is a natural number, which is a multiple of 2, such that P3=0, 2, 4, . . . , N−2 when P1% 4=2 and is a natural number, which is a multiple of 4, such that P3=0, 4, 8, . . . , N−4 when P1% 4=0.
Here, %4 represents a modulo-4 operation.
The spatial distance may be defined as in the following Expression 1.

S(j1,j2)=f(j1,j2)+f(Π(j1),Π(j2))  [Expression 1]

Here, f(u,v)=min [|u−v|,k−|u−v|] and f(j1, j2) denotes a distance before interleaving, f(Π(j1),Π(j2)) denotes a distance after interleaving. The spatial distance can be calculated for all index combinations (j1, j2). In addition, Smin denotes the minimum spatial distance of the CTC interleaver among spatial distances of the index combinations.
Specifically, a parameter P0, which is relatively prime number to N, is selected in the following manner.
Preferably, P0 is an integer which is among relative prime numbers with N. However, for some data block sizes.
Smin may be sorted by magnitude. CTC interleaving patterns may be generated using all combinations (P1, P2, P3)={(0, 0, 0), (0, 0, 2), . . . , (2, 0, 0), (2, 0, 2, or 4), . . . , (N−2, N−4, N−2, or N−4) together with P0. Smin may be calculated for each combination of (P1, P2, P3). After minimum spatial distances Smin are calculated respectively for all parameter combinations, the top 5 parameter combinations may be extracted from among parameter combinations having the minimum spatial distances when the parameter combinations are sorted in decreasing order of the minimum spatial distance. The 5 parameter combinations having the minimum spatial distances sorted and extracted in this manner may be used in the second step of the method of designing and optimizing CTC interleaver parameters.
In the second step, a Return To Zero (RTZ) spatial distance may be calculated using the extracted parameter combinations. The RTZ sequence may be represented as follows taking into consideration CTC encoder generation polynomial equations.
















idx1 − idx2 = 1
Weight = 6
13



idx1 − idx2 = 2
Weight = 7
201



idx1 − idx2 = 3
Weight = 9
2003



idx1 − idx2 = 4
Weight = 9
30002



idx1 − idx2 = 5
Weight = 11
100002



idx1 − idx2 = 6
Weight = 10
3000001



idx1 − idx2 = 7
Weight = 12
10000001



idx1 − idx2 = 7
Weight = 14
20000002



idx1 − idx2 = 7
Weight = 12
30000003



idx1 − idx2 = 8
Weight = 14
100000003



idx1 − idx2 = 9
Weight = 15
2000000001



idx1 − idx2 = 10
Weight = 17
20000000003



idx1 − idx2 = 11
Weight = 17
300000000002



idx1 − idx2 = 12
Weight = 19
1000000000002



idx1 − idx2 = 13
Weight = 18
30000000000001



idx1 − idx2 = 14
Weight = 20
100000000000001



idx1 − idx2 = 14
Weight = 22
200000000000002



idx1 − idx2 = 14
Weight = 20
300000000000003







.


.


.









When the result of interleaving of an input RTZ sequence by applying bit pair swapping to the input RTZ sequence in the first step of the interleaving procedure is also an RTZ sequence, a spatial distance may be calculated for the RTZ sequence. Here, SRTZ,min is the minimum spatial distance of the RTZ sequence.
After minimum spatial distances SRTZ,min are calculated respectively for the each parameter combinations extracted in the first step, the calculated five minimum spatial distances SRTZ,min may sorted in decreasing order. Parameter combinations having the 5 minimum RTZ spatial distances obtained in this manner may be used in the third step of the method of designing and optimizing CTC interleaver parameters.
In the third step, the minimum distance is calculated using an Error IMpulse (EIM) method.
The CTC encoder may perform the EIM method using 2-bit data input to the CTC encoder. In order to calculate the minimum distance dmin using interleaving patterns generated using the parameter combinations, each of the first and second encoders may perform the EIM method twice using the input bits A and B through its the first and second encoders. Thus, the minimum distance of code may be checked using the EIM method. Max-Log-MAP decoding having 64 repetitions may be used for the EIM method. This may be represented by the following algorithm.














set Amin = d1 + 0.5



 for i=1 to n do









A = d0 −0.5;



set[{{circumflex over (x)} = x}= TRUE



while [{{circumflex over (x)} = x}= TRUE] and {A≦ Amin −1.0}









do









 * A= A+1.0 ;



 * y= {−1,•••, −1, −1+ A, −1, −1,•••, −1}



Where −1+A is in position i;



* ML decoding of y {circumflex over (x)} ;



* if ({circumflex over (x)} ≠ x) then [{{circumflex over (x)} = x}= FALSE];









end while









Amin = A









end for







dmin is the integer part of Amin









After minimum distances dmin are calculated respectively for the each parameter combinations obtained in the second step, the top three minimum distances dmin may be obtained when the calculated minimum distances dmin are sorted in decreasing order. Parameter combinations having the three minimum distances dmin obtained in this manner may be used in the last step, namely, the fourth step, of the method of designing and optimizing CTC interleaver parameters. Here, the minimum distance may represent a measure of performance since performance generally increases as the minimum distance increases.
In the fourth step, performance is estimated using mother code rates of 1⁄2 and 1⁄3. A BLock Error Rate (BLER) may be estimated after the motor code rate is set to 1⁄2 and 1⁄3 for the parameter combinations extracted in the third step. Parameter combinations which exhibit highest performance for all the code rates 1⁄2 and 1⁄3 may be selected after performance is estimated for each data block size.
The present invention suggests the following data block sizes and the following CTC interleaver parameters corresponding to the data block sizes according to the present invention described above. Some CTC interleaver parameters of the following Table 3 are changed from those of the Table 2.













TABLE 3






Index
NEP
P0
P1
P2
P3






















1
48
5
0
0
0



2
64
11
12
0
12



3
72
11
18
0
18



4
80
7
4
32
36



5
88
13
36
36
32



6
96
13
24
0
24



7
104
7
4
8
48



8
120
11
30
0
34



9
128
13
46
44
30



10
136
13
58
4
58



11
144
11
6
0
6



12
152
11
38
12
74



13
160
13
68
76
64



14
176
17
52
68
32



15
184
13
2
0
2



16
192
7
58
48
10



17
200
11
76
0
24



18
208
11
10
32
42



19
216
11
54
56
2



20
232
11
70
60
58



21
240
13
60
0
60



22
248
13
6
84
46



23
256
11
64
8
8



24
264
13
72
68
8



25
272
13
82
44
38



26
288
17
74
72
2



27
296
13
0
84
64



28
304
13
130
112
46



29
312
11
32
124
108



30
320
17
84
108
132



31
328
17
148
160
76



32
344
17
160
116
52



33
352
17
106
56
50



34
360
17
40
132
128



35
368
19
88
0
172



36
376
13
110
92
14



37
384
11
96
48
144



38
400
19
142
0
142



39
408
23
42
20
46



40
416
17
102
132
178



41
424
17
138
56
18



42
432
17
126
92
74



43
440
19
48
20
144



44
456
17
184
0
48



45
464
17
62
52
114



46
472
19
40
104
28



47
480
13
120
60
180



48
488
17
140
92
220



49
496
17
194
0
58



50
512
19
64
52
124



51
528
17
36
196
100



52
544
19
222
248
134



53
576
23
76
220
92



54
592
23
96
172
36



55
608
23
288
244
140



56
624
23
286
220
70



57
640
23
84
296
236



58
656
23
24
300
52



59
688
19
320
4
324



60
704
19
52
76
256



61
720
23
130
156
238



62
736
29
126
208
270



63
752
23
26
24
230



64
768
29
252
0
8



65
800
23
150
216
150



66
816
29
342
132
42



67
832
23
354
164
198



68
848
29
234
388
82



69
864
29
216
272
180



70
880
29
410
328
218



71
912
29
14
264
94



72
928
23
446
392
186



73
944
23
356
68
332



74
960
23
186
61
10



75
976
31
134
124
366



76
992
29
358
480
362



77
1024
29
320
236
324



78
1056
31
86
380
250



79
1088
31
432
216
524



80
1152
31
534
372
246



81
1184
31
2
568
94



82
1216
31
368
584
524



83
1248
31
88
404
608



84
1280
29
152
8
24



85
1312
31
214
160
506



86
1376
31
218
20
670



87
1408
29
474
584
118



88
1440
41
288
556
672



89
1472
29
164
424
76



90
1504
31
254
416
474



91
1536
31
34
564
710



92
1600
31
454
216
234



93
1632
29
334
564
66



94
1664
31
156
568
56



95
1696
37
722
136
698



96
1728
31
176
152
516



97
1760
23
646
484
850



98
1824
41
774
548
898



99
1856
47
576
212
728



100
1888
39
342
596
798



101
1920
43
318
556
778



102
1952
35
94
144
686



103
1984
43
84
488
92



104
2048
31
2
332
622



105
2112
43
96
720
980



106
2176
37
428
976
28



107
2304
41
16
484
888



108
2368
47
228
440
724



109
2432
43
452
888
96



110
2496
43
0
208
528



111
2560
53
264
488
824



112
2624
47
378
1092
1250



113
2752
37
430
880
970



114
2816
31
624
704
400



115
2880
53
184
996
1336



116
2944
41
338
660
646



117
3008
43
916
1136
912



118
3072
53
184
824
1368



119
3200
43
1382
632
1086



120
3264
49
142
828
1354



121
3328
37
258
28
1522



122
3392
51
460
56
1608



123
3456
43
170
920
1518



124
3520
57
776
1232
1012



125
3648
49
132
720
276



126
3712
41
1328
772
1036



127
3776
53
772
256
408



128
3840
53
92
1124
476



129
3904
51
664
200
64



130
3968
57
1296
760
1360



131
4096
55
148
808
308



132
4160
79
214
308
262



133
4224
59
14
668
1474



134
4288
57
662
1516
42



135
4352
59
2052
712
1804



136
4416
59
1342
1968
1562



137
4544
65
1380
1068
1036



138
4608
67
954
1140
1566



139
4672
67
410
1020
114



140
4736
59
2
956
458



141
4800
53
66
24
2









Compared to Table 2, in the case of index 16, the data block size (or bit size) is 192 and the CTC interleaver parameters P0, P1, P2, and P3 are changed to 7, 58, 48, and 10. In the case of index 34, the data block size is 360 and the CTC interleaver parameters P0, P1, P2, and P3 are changed to 17, 40, 132, and 128, respectively. In the case of index 42, the data block size is 432 and the CTC interleaver parameters P0, P1, P3, and P4 are changed to 17, 126, 92, and 74, respectively. In the case of index 74, the data block size is 960 and the CTC interleaver parameters P0, P1, P2, and P3 are changed to 23, 186, 61, and 10, respectively. In the case of index 101, the data block size is 1920 and the CTC interleaver parameters P0, P1, P2, and P3 are changed to 43, 318, 556, and 778, respectively. In the case of index 115, the data block size is 2880 and the CTC interleaver parameters P0, P1, P2, and P3 are changed to 53, 184, 996, and 1336, respectively. In the case of index 128, the data block size is 3840 and the CTC interleaver parameters P0, P1, P2, and P3 are changed to 53, 92, 1124, and 476, respectively. The changed portions of Table 3 are shown in the following Table 4.
That is, Table 4 illustrates information of some data block sizes whose CTC interleaver parameters have been changed from those of Table 3.













TABLE 4






Index
NEP
P0
P1
P2
P3






















16
192
7
58
48
10



34
360
17
40
132
128



42
432
17
126
92
74



74
960
23
186
61
10



101
1920
43
318
556
778



115
2880
53
184
996
1336



128
3840
53
92
1124
476









As shown in Table 4, new CTC interleaver parameters are provided for the data block sizes 192, 360, 432, 960, 1920, 2880, and 3840 in order to improve performance. The remaining CTC interleaver parameters may be identical to those of the IEEE 802.16e system to achieve downward compatibility (i.e., to support the legacy system).
The following Table 5 is created by removing 34 data block sizes and corresponding CTC interleaver parameters from those of Table 3 and adding 42 new data block sizes and corresponding CTC interleaver parameters.













TABLE 5






Index
NEP
P0
P1
P2
P3






















1
48
5
0
0
0



2
64
11
12
0
12



3
72
11
18
0
18



4
80
7
4
32
36



5
88
13
36
36
32



6
96
13
24
0
24



7
104
7
4
8
48



8
120
11
30
0
34



9
128
13
46
44
30



10
136
13
58
4
58



11
144
11
6
0
6



12
152
11
38
12
74



13
160
13
68
76
64



14
176
17
52
68
32



15
184
13
2
0
2



16
192
7
58
48
10



17
200
11
76
0
24



18
208
11
10
32
42



19
216
11
54
56
2



20
232
11
70
60
58



21
240
13
60
0
60



22
248
13
6
84
46



23
256
11
64
8
8



24
264
13
72
68
8



25
272
13
82
44
38



26
288
17
74
72
2



27
296
13
0
84
64



28
304
13
130
112
46



29
312
11
32
124
108



30
320
17
84
108
132



31
328
17
148
160
76



32
344
17
160
116
52



33
352
17
106
56
50



34
360
17
40
132
128



35
368
19
88
0
172



36
376
13
110
92
14



37
384
11
96
48
144



38
400
19
142
0
142



39
416
17
102
132
178



40
432
17
126
92
74



41
440
19
48
20
144



42
456
17
184
0
48



43
472
19
40
104
28



44
480
13
120
60
180



45
496
17
194
0
58



46
512
19
64
52
124



47
528
17
36
196
100



48
544
19
222
248
134



49
552
13
198
180
190



50
568
19
102
140
226



51
584
21
74
20
214



52
600
31
12
272
28



53
608
23
288
244
140



54
624
23
286
220
70



55
640
23
84
296
236



56
656
23
24
300
52



57
664
23
272
220
60



58
680
19
48
240
144



59
696
31
252
216
48



60
712
25
214
180
286



61
720
23
130
156
238



62
736
29
126
208
270



63
752
23
26
24
230



64
768
29
252
0
8



65
776
29
100
196
140



66
800
23
150
216
150



67
824
29
130
332
42



68
848
29
234
388
82



69
872
29
408
300
316



70
888
25
414
84
414



71
912
29
14
264
94



72
936
25
272
168
400



73
960
53
62
12
2



74
984
31
142
40
342



75
1000
29
290
148
446



76
1024
29
320
236
324



77
1048
27
424
212
416



78
1072
35
290
228
390



79
1096
23
178
392
430



80
1112
33
38
244
550



81
1136
37
170
276
134



82
1160
31
314
348
222



83
1184
31
2
568
94



84
1216
31
368
584
524



85
1248
31
88
404
608



86
1280
29
152
8
24



87
1312
31
214
160
506



88
1336
39
2
168
646



89
1368
29
570
348
574



90
1392
31
218
484
446



91
1424
31
676
124
184



92
1448
33
254
372
158



93
1480
31
32
716
736



94
1504
31
254
416
474



95
1536
31
34
564
710



96
1560
29
300
248
568



97
1600
31
454
216
234



98
1640
33
164
432
748



99
1672
35
164
368
700



100
1712
41
4
848
332



101
1752
31
314
656
666



102
1784
33
886
888
518



103
1824
41
774
548
898



104
1864
33
504
444
664



105
1896
35
936
940
832



106
1920
43
318
556
778



107
1952
35
94
144
686



108
2000
37
290
692
638



109
2048
31
2
332
622



110
2096
39
400
688
68



111
2144
29
298
252
610



112
2192
39
1074
148
710



113
2232
29
240
496
1100



114
2280
41
474
376
814



115
2328
41
254
884
1054



116
2368
47
228
440
724



117
2432
43
452
888
96



118
2496
43
0
208
528



119
2560
53
264
488
824



120
2624
47
378
1092
1250



121
2752
37
430
880
970



122
2816
31
624
704
400



123
2880
43
720
360
540



124
2944
41
338
660
646



125
3008
43
916
1136
912



126
3072
53
184
824
1368



127
3200
43
1382
632
1086



128
3264
49
142
828
1354



129
3328
37
258
28
1522



130
3392
51
460
56
1608



131
3456
43
170
920
1518



132
3520
57
776
1232
1012



133
3648
49
132
720
276



134
3712
41
1328
772
1036



135
3776
53
772
256
408



136
3840
53
92
1124
476



137
3904
51
664
200
64



138
3968
57
1296
760
1360



139
4096
55
148
808
308



140
4160
79
214
308
262



141
4224
59
14
668
1474



142
4288
57
662
1516
42



143
4352
59
2052
712
1804



144
4416
59
1342
1968
1562



145
4544
65
1380
1068
1036



146
4608
67
954
1140
1566



147
4672
67
410
1020
114



148
4736
59
2
956
458



149
4800
53
66
24
2









As shown in Table 5, the 42 newly added data block sizes are 552, 568, 584, 600, 664, 680, 696, 712, 776, 824, 872, 888, 936, 984, 1000, 1048, 1072, 1096, 1112, 1136, 1160, 1336, 1368, 1392, 1424, 1448, 1480, 1560, 1640, 1672, 1712, 1752, 1784, 1864, 1896, 2000, 2096, 2144, 2192, 2232, 2280, and 2328.
Table 6 shows 39 data block sizes, which are preferable for use in interleaving among data block sizes shown in Table 5, and CTC interleaver parameters values corresponding to the 39 data block sizes.













TABLE 6






Index
NEP
P0
P1
P2
P3






















1
48
5
0
0
0



2
64
11
12
0
12



3
72
11
18
0
18



4
80
7
4
32
36



5
88
13
36
36
32



6
96
13
24
0
24



7
104
7
4
8
48



8
120
11
30
0
34



9
136
13
58
4
58



10
152
11
38
12
74



11
176
17
52
68
32



12
200
11
76
0
24



13
216
11
54
56
2



14
248
13
6
84
46



15
288
17
74
72
2



16
320
17
84
108
132



17
352
17
106
56
50



18
400
19
142
0
142



19
456
17
184
0
48



20
512
19
64
52
124



21
568
19
102
140
226



22
640
23
84
296
236



23
720
23
130
156
238



24
800
23
150
216
150



25
912
29
14
264
94



26
1024
29
320
236
324



27
1160
31
314
348
222



28
1312
31
214
160
506



29
1448
33
254
372
158



30
1640
33
164
432
748



31
1864
33
504
444
664



32
2096
39
400
688
68



33
2328
41
254
884
1054



34
2624
47
378
1092
1250



35
2944
41
338
660
646



36
3328
37
258
28
1522



37
3776
53
772
256
408



38
4224
59
14
668
1474



39
4800
53
66
24
2









The CTC interleaver parameter tables may be expressed according to data block sizes as described above with reference to Tables 2 to 6 according to the CTC interleaver design and optimization procedure according to the present invention.
FIGS. 3 and 4 illustrate comparison between BLER performance of a CTC interleaver using data block sizes and CTC interleaver parameters suggested in the present invention and BLER performance of the conventional IEEE 802.16e CTC interleaver for each mother code rate.
Specifically, FIGS. 3 and 4 illustrate comparison between a Signal to Noise Ratio (SNR) required for the data block size when mother code rate is 1⁄2 and 1⁄3 and when BLER is 10%, 1%, and 0.1%. Performance increases as the data block size increases since the SNR decreases as the data block size increases as shown in FIGS. 3 and 4. This indicates that the performance of the CTC interleaver according to the present invention is better than the CTC interleaver of the conventional IEEE 802.16m system using small data block sizes.
The apparatus and method for transmitting data using the CTC interleaver have been described above. An apparatus and method for receiving data using the CTC interleaver corresponding to the transmission apparatus and method are described below with reference to the above description.
The apparatus for receiving data using the CTC interleaver may include a first decoder that decodes received values of data bits input through two input terminals and outputs a Log Likelihood Ratio (LLR) of first decoded bits, a CTC interleaver that interleaves received values of the input data bits using 4 CTC interleaver parameters P0, P1, P2, and P3 corresponding to the size of the input data bits, and a second decoder that decodes the received value of the interleaved data bits and outputs a Log Likelihood Ratio (LLR) of second decoded bits. The functions and processes of the interleaver of the CTC decoder are identical to those of the interleaver of the CTC encoder. Thus, a detailed description of the interleaver of the CTC decoder is omitted herein.
The above embodiments are provided by combining components and features of the present invention in specific forms. The components or features of the present invention should be considered optional unless explicitly stated otherwise. The components or features may be implemented without being combined with other components or features. The embodiments of the present invention may also be provided by combining some of the components and/or features. The order of the operations described above in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It will be apparent that claims which are not explicitly dependent on each other can be combined to provide an embodiment or new claims can be added through amendment after this application is filed.
The embodiments of the present invention can be implemented by hardware, firmware, software, or any combination thereof. In the case where the present invention is implemented by hardware, an embodiment of the present invention may be implemented by one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, or the like.
In the case where the present invention is implemented by firmware or software, the embodiments of the present invention may be implemented in the form of modules, processes, functions, or the like which perform the features or operations described above. Software code can be stored in a memory unit so as to be executed by a processor. The memory unit may be located inside or outside the processor and can communicate data with the processor through a variety of known means.
As is apparent from the above description, an apparatus and method for a transmitting end to transmit data using a Convolutional Turbo Code (CTC) encoder in a mobile communication system according to the present invention have a variety of advantages.
For example, it is possible to significantly reduce padding overhead by applying additional input data bit sizes suggested in the present invention.
The reduction of the padding overhead also enables more efficient data transmission.
The apparatus and method for transmitting data using a CTC interleaver according to the present invention can be used industrially.
Those skilled in the art will appreciate that the present invention may be embodied in other specific forms than those set forth herein without departing from the spirit and essential characteristics of the present invention. The above description is therefore to be construed in all aspects as illustrative and not restrictive. The scope of the invention should be determined by reasonable interpretation of the appended claims and all changes coming within the equivalency range of the invention are intended to be embraced in the scope of the invention.

## Claims

1. A method of transmitting data using a Convolutional Turbo Code (CTC) encoder by a transmitting end in a mobile communication system, the method comprising:
providing input data bits; and
interleaving the input data bits using 4 CTC interleaver parameters (P0, P1, P2, and P3) corresponding to a size of the input data bits inputted to two input ports of a CTC interleaver,
wherein the size (NEP) of the input data bits is one of bit sizes in Table A, and
wherein P0, P1, P2, and P3 corresponding to the size (NEP) of the input data bit are determined as one row selected among in Table A:














TABLE A






Index
NEP
P0
P1
P2
P3






















1
64
11
12
0
12



2
80
7
4
32
36



3
88
13
36
36
32



4
104
7
4
8
48



5
120
11
30
0
34



6
136
13
58
4
58



7
152
11
38
12
74



8
176
17
52
68
32



9
200
11
76
0
24



10
248
13
6
84
46



11
320
17
84
108
132



12
352
17
106
56
50



13
400
19
142
0
142



14
456
17
184
0
48



15
512
19
64
52
124



16
568
19
102
140
226



17
640
23
84
296
236



18
720
23
130
156
238



19
800
23
150
216
150



20
912
29
14
264
94



21
1024
29
320
236
324



22
1152
31
534
372
246



23
1312
31
214
160
506



24
1440
41
288
556
672



25
1632
29
334
564
66



26
1856
47
576
212
728



27
2112
43
96
720
980



28
2368
47
228
440
724



29
2624
47
378
1092
1250



30
2944
41
338
660
646



31
3328
37
258
28
1522



32
3776
53
772
256
408



33
4224
59
14
668
1474.

2. The method according to claim 1, wherein the CTC interleaver parameter P0 is an integer close to √{square root over (2N)} among the relative prime numbers with N.

3. The method according to claim 1, wherein the size (NEP) of the input data bits include at least one additional bit size, other than 48, 72, 96, 144, 192, 216, 240, 288, 360, 384, 432, 480, 960, 1920, 2800, 3840, and 4800 bits, within a size range between 48 bits to 4800 bits.

4. The method according to claim 1, wherein P0 is relative prime number with N which is 1⁄2 of the size (NEP) of the input data bits, P1 is a multiple of 2 among a number set, P2 is a multiple of 4 among the number set, wherein the number set is defined by a set of integers greater than zero, and wherein P3 is a multiple of 2 among the number set when (P1 modulo 4)=2, and P3 is a multiple of 4 among the number set when (P1 modulo 4)=0.

5. The apparatus according to claim 1, wherein P0 is relative prime number with N which is 1⁄2 of the size (NEP) of the input data bits, P1 is a multiple of 2 among a number set, P2 is a multiple of 4 among the number set, wherein the number set is defined by a set of integers greater than zero, and wherein P3 is a multiple of 2 among the number set when (P1 modulo 4)=2, and P3 is a multiple of 4 among the number set when (P1 modulo 4)=0.

6. An apparatus for transmitting data using a Convolutional Turbo Code (CTC) encoder in a mobile communication system, the apparatus comprising:
a provider for providing input data bits; and
a CTC interleaver for interleaving the input data bits using 4 CTC interleaver parameters (P0, P1, P2, and P3) corresponding to a size of the input data bits,
wherein the size (NEP) of the input data bits is one of bit sizes in Table A, and
wherein P0, P1, P2, and P3 corresponding to the size (NEP) of the input data bit are determined as one row selected among in Table A:














TABLE A






Index
NEP
P0
P1
P2
P3






















1
64
11
12
0
12



2
80
7
4
32
36



3
88
13
36
36
32



4
104
7
4
8
48



5
120
11
30
0
34



6
136
13
58
4
58



7
152
11
38
12
74



8
176
17
52
68
32



9
200
11
76
0
24



10
248
13
6
84
46



11
320
17
84
108
132



12
352
17
106
56
50



13
400
19
142
0
142



14
456
17
184
0
48



15
512
19
64
52
124



16
568
19
102
140
226



17
640
23
84
296
236



18
720
23
130
156
238



19
800
23
150
216
150



20
912
29
14
264
94



21
1024
29
320
236
324



22
1152
31
534
372
246



23
1312
31
214
160
506



24
1440
41
288
556
672



25
1632
29
334
564
66



26
1856
47
576
212
728



27
2112
43
96
720
980



28
2368
47
228
440
724



29
2624
47
378
1092
1250



30
2944
41
338
660
646



31
3328
37
258
28
1522



32
3776
53
772
256
408



33
4224
59
14
668
1474.

7. The apparatus according to claim 6, wherein the CTC interleaver parameter P0 is an integer close to √{square root over (2N)} among relative prime numbers with N.

8. The apparatus according to claim 6, wherein the size (NEP) of the input data bits include at least one additional bit size, other than 48, 72, 96, 144, 192, 216, 240, 288, 360, 384, 432, 480, 960, 1920, 2800, 3840, and 4800 bits, within a size range between 48 bits to 4800 bits.