AU2003268814B2 - Interleaver and interleaving method in a communication system - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): SAMSUNG ELECTRONICS CO., LTD.

Invention Title: INTERLEAVER AND INTERLEAVING METHOD IN A COMMUNICATION SYSTEM The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 INTERLEAVER AND INTERLEAVING METHOD SIN A COMMUNICATION SYSTEM O BACKGROUND OF THE INVENTION Field of the Invention: SThe present invention relates generally to interleaving in a 00 communication system. The present application is a Divisional of Patent Application CNo. 2003208028.

SDescription of the Related Art: While a sub-block channel interleaver designed in accordance with the IS-2000 Release C(lxEV-DV) F/L specification performs P-BRO operation for row permutation similarly to an existing channel interleaver designed in accordance with the IS-2000 Release A/B spec., the sub-block channel interleaver differs from the channel interleaver in that the former generates read addresses in a different manner and requires full consideration of the influence of a selected interleaver parameter on Quasi- Complementary Turbo code (QCTC) symbol selection.

Hence, there is a need for analyzing the operating principles of the subblock channel interleaver and the channel interleaver and creating criteria on which to generate optimal parameters for the channel interleavers. The optimal parameters will offer the best performance in channel interleavers built in accordance with both the IS- 2000 Release A/B and IS-2000 Release C.

SUMMARY OF THE INVENTION According to one aspect of the invention there is provided a method of determining interleaver parameters m and J according to an interleaver size N to sequentially store input data in a memory to be arranged in 2 m rowx(J-l) column matrix structure and partial-bit reversal order (P-BRO) interleaving the stored data, the parameters N, m, J, and remainder R being expressed as N=2mxJ+R the method comprising: calculating a first variable a by (log 2 N log 2 and a second variable 3 by (2io, NJ); comparing the first variable with a selected first threshold; H:\angelal\keep\Amended Pages 2003268814.doc 20/06/05

I

3 C comparing the interleaver size N with at least one predetermined second Sthreshold determined by a ratio of the second variable; determining a first parameter J according to the comparison results; and SI N N log 2 determining a second parameter m by

L

0O According to another aspect of the invention there is provided an 00 interleaver for use in a communication system, comprising: C¢I a memory having a rowxcolumn matrix; and O an address generator adapted to, in use, partial-bit reversal order (P- 10 BRO) interleave addresses of the memory, calculate a first variable a by (log 2 N- Log 2 N) using a given interleaver size N and a second variable p by (2Lgi 2 NJ), compare the first variable with a predetermined first threshold, compare the interleaver size N with at least one predetermined second threshold determined by a ratio of the second variable, determine a first parameter J according to the comparison log 2 results, calculate a second parameter m by ,J calculate a third parameter R by N=2mxJ+R, sequentially arrange by columns an input data stream of size N in a matrix having 2m rows and columns, and in R rows in a Jth column P-BRO interleave the arranged data and generate read addresses for reading the interleaved data by rows.

BRIEF DESCRIPTION OF THE DRAWINGS Objects, features and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments thereof when taken in conjunction with the accompanying drawings, in which: Fig. 1 illustrates P-BRO interleaving when N=384, m=7 and J=3 according to an embodiment of the present invention; Fig. 2 illustrates distances between read addresses after P-BRO interleaving when N=384, m=7 and J=3 according to an embodiment of the present invention; Fig. 3 illustrates P-BRO interleaving when N=408, m=7, J=3 and R=24 according to an embodiment of the present invention; H:\angelal\keep\Amended Pages 2003268814.doc 20/06/05 4 Fig. 4 illustrates the minimum intra-row distance after P-BRO interleaving when N=408, m=7 and J=3 according to an embodiment of the present invention; Fig. 5 is a block diagram of an interleaver to which an embodiment of the present invention is applied; Fig. 6 is a flowchart illustrating a first example of the optimal interleaver parameters determining operation according to an embodiment of the present invention; and Fig. 7 is a flowchart illustrating another example of the optimal interleaver parameters determining operation according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Several preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same or similar elements are denoted by the same reference numerals, even though they are depicted in different drawings. In the following description, a detailed description of known functions or configurations incorporated herein have been omitted for conciseness.

Hereinbelow, a description will be made of P-BRO interleaving to which various embodiments of the present invention are applied, as well as the principle of determining parameters for optimal P-BRO interleaving in accordance with embodiments of the present invention.

Fig. 5 is a block diagram of a P-BRO interleaver to which an embodiment of the present invention is applied. Referring to Fig. 5, an address generator 511 receives an interleaver size N, a first parameter m Bit_Shift), a second parameter J 3 0 Up_Limit) and a clock signal Clock, and generates read addresses to read bit symbols from an interleaver memory 512. The parameters m and J are determined in an higherlayer controller (not shown) and provided to the address generator 511, or determined according to the interleaver size N in the address generator 511. The interleaver memory 512 sequentially stores input bit symbols at write addresses corresponding to count values of a counter 513 in a write mode, and outputs bit symbols from read addresses received from the address generator 511 in a read mode. The counter 513 \\melbfiles\hme$\Priyanka\Keep\peci\PS1504 DIV.doc 2/12/03 5 receives the clock signal Clock, generates a count value, and provides it as a write Saddress Write ADDR to the interleaver memory 512.

As described above, the P-BRO interleaver writes input data sequentially in the interleaver memory 512 in the write mode and reads data from the interleaver memory 512 according to read addresses generated from the address generator 511. For 0 details of the P-BRO interleaver, reference is made to Patent No. WO 00/35102, 00 priority date December 10, 1998, the entire contents of which are expressly incorporated herein.

S In operation, the address generator 511 generates a read address Ai for symbol permutation by A, 2"(i mod BRO, Jj) (1) where i=0, N-1 and N=2 m xJ.

In Eq. N denotes the size of an interleaver input sequence and m and J are interleaver parameters called Up_Limit and Bit_Shift, respectively.

Fig. 1 illustrates P-BRO interleaving when N=384, m=7 and J=3.

Referring to Fig. 1, an interleaving matrix has 2m rows starting from index 0 and J columns starting from index 0. After step 101, the row index and column index of a symbol in the resulting matrix are expressed as Li/JJ and (i mod respectively.

Therefore, after 2m(i mod Li/JJ, an ith symbol in an input sequence has a number corresponding to an Li/JJth row and an (I mod J) column as its read address. J symbols are in each row and the distance between symbols is 2 m in the row.

The row index Li/JJ is BRO-operated in step 102. If the distance between symbols in adjacent rows of the same column is row distance drow, the BRO operation of the row indexes results in a row permutation such that two minimum row distances drow are 2 m 2 and 2" m as illustrated in Fig. 2. Thus, after 2 m (i mod BROmLi/J], the ith symbol in the input sequence has a number corresponding to a BROmLi/JJth row and an (i mod J)th column as its read address in the third matrix from the left.

In summary, a read address sequence is generated by row permutations of a 2mxJ matrix in the P-BRO interleaver. The row-permuted matrix is read first by rows from the top to the bottom, then subsequently reading each row from the left to the right.

H:\angelal\keep\Amended Pages 2003268814.doc 20/06/05 6 For clarity of description, the distance between adjacent addresses in the same row is defined as "intra-row distance dintra". If J l, dintra=2 m If there is no intra-row distance.

The distance between adjacent addresses in different rows, that is, the distance between the last address in a row and the first address in the next row is defined as "inter-row distance dinter". dinter is one of a plurality of values calculated from a function of the parameters m and J. When m and J are determined, the resulting minimum inter-row distance dinter is defined as Since two minimum rows distances drow are 2 m- 2 and 2 m in d ai 2 m 2 If J 1, d 2 Else, dinr (J 1) 2 (2 J 3).2m (2) The reason for computing d,"r by Eq. when J#l is apparent in Fig. 2. If J=l, which implies that the interleaving matrix has only one column, is that 2 is, 2 m 2 As described above, the interleaver parameters m and J are used as the numbers of rows and columns in a read address sequence matrix and parameters for a function that determines distances between read addresses. Consequently, the characteristics of the P-BRO channel interleaver depend on the interleaver parameters m and J.

Before presenting a description of a method of determining sub-block channel interleaver parameters that ensure the best interleaving performance according to an embodiment of the present invention, the purposes of channel interleavers in the IS-2000 specifications, Releases A/B and C will first be described. Following that, the interleaver parameter determination will then be described separately in two cases: N=2 m xJ; and N=2 m xJ+R.

The purpose of channel interleaving in the IS-2000 specification, Release A/B, is to improve decoding performance, which is degraded when fading adversely influences successive code symbols, through error scattering resulting from symbol \\melb_files\home$\Priyanka\Keep\speci\P51504 DIV.doc 2/12/03 7 permutation. To improve decoding performance, interleaving must be performed such that the distance between adjacent addresses (inter-address distance) is maximized.

Meanwhile, the purpose of sub-block channel interleaving as described in the IS-2000 specification, Release C, is to allow a QCTC symbol selector at the rear end of an interleaver to select appropriate code symbols according to a coding rate and thus ensure the best performance at the coding rate, as well as to scatter errors through symbol permutation. To achieve this purpose, interleaving must be performed such that inter-address distances are maximized and are uniform.

Accordingly, to satisfy the requirements of the channel interleaver of the IS- 2000 specification, Release A/B, and the sub-block channel interleaver of the IS-2000 specification, Release C, an interleaver must be designed so that a read address sequence is uniformly permuted by interleaving. This is possible by determining the interleaver parameters m and j that maximize a minimum inter-address distance and minimize the difference between inter-address distances.

As stated before, the inter-address distances are categorized into the intrarow distance dintra and the inter-row distance dinter. The intra-row distance is a function of m and the inter-row distance is a function of m and J. Since there are a plurality of inter-row distances, a minimum inter-row distance is calculated. A minimum inter-address distance is always 2 m 2 when J is 1, and the smaller of the minimum interrow distance d"n and the minimum intra-row distance d"a when J is not 1. The difference between inter-address distances is 2 m 2 when J is 1, since the intra-row distance dintra is 0, and is equal to the difference between the intra-row distance dintra and the minimum inter-row distance d" when J is not 1.

This can be expressed as follows: If J=1, 0-2m2 =2 m 2 Else, din,,, 2" 2.J-5 .2m- (3) Since N=2 m xJ, 2m is replaced by N/J in Eq. it follows that \\melbfiles\home$\Priyanka\Keep\peci\P51504 DIV.doc 2/12/03 8 S N N If J 2 0.25-, 4J J Kin .J 5.1 N 2.51 Else, d -din= 2-J-5 1- -N 212J J (4) When J=3 in Eq. the difference between inter-address distances is minimized. Thus ditra d =0.166667N.

Table 1 below illustrates changes in inter-read address distances as m increases when N=384. When J=3, a maximum difference between inter-address distances is minimized, 64 and a minimum inter-address distance d"' a is maximized, 128.

Table 1 N m J dinta dt dintra dt d 4 24 16 360 344 16 384 5 12 32 336 304 32 6 6 64 288 224 64 7 3 128 192 64 128 The method of determining optimal interleaver parameters when N=2mxJ has been described above. Now, a method of determining optimal interleaver parameters when N=2 m xJ+R will be described. Here, R is the remainder of dividing N by 2m. Thus R is a positive integer less than 2m.

Fig. 3 illustrates P-BRO interleaving when N=408, m=7, J=3 and RO.

Referring to Fig. 3, similarly to the case where R=0, numbers in a row-permuted matrix after step 302 are read as read addresses by rows from the top to the bottom, reading each row from the left to the right, as described in step 303. Since R O, the number of columns is J+l, and numbers are filled in only R rows of a (J+l)th column with no numbers in the other (2m-R) rows.

In summary, when R#0, a read address sequence is generated by a row permutation of a 2 m xJ matrix, each row including J or J+l elements in the P-BRO interleaver. The row-permuted matrix is read by rows from the top to the bottom, reading each row from the left to the right.

\\melb-file\horeS\Priyanka\xeep\speci\PS504 OIV.doc 2/12/03 9 Furthermore, when R O, the interleaver parameters m and J are determined such that a minimum inter-read address distance is maximized and the difference between inter-read address distances is minimized.

An inter-row distance dinter is a function of m, 2 m irrespective of whether R=0 or RO.

However, while the minimum inter-row distance d"i is a function ofm and J when R=0, it is a function of m, J and R when RO.

The minimum inter-row distance is determined according to J by Eq. and Eq. When J =1, For 0 R 3.2-2, d,"r 2m-2 For 3-2m- 2 <R <2 m d 2 m 1 When J 1, For 0 R di m "r (J 2" 2m" (2J 3) 2m-' (6) For 2 m <R <3.2m- 2 d"i" 2"- 2 For 3 2n-2 R d J 2 2" 1 (2J 2m-1 Fig. 4 illustrates how Eq. is derived when m=7 and J=3. Referring to Fig.

4, when 05R<2m 1 the inter-row distance between two adjacent rows having a row distance dr o w of 2 the last column of the upper row being empty, is a minimum interrow distance (dr (2J When 2 m 2 m 2 the inter-row distance between two adjacent rows having a row distance drow of 2 m 2 the last column of the upper row being empty, is a minimum inter-row distance (din r (4J 2m 2 When 3 2 m-2<R< 2 m, the inter-row distance between two adjacent rows having a row distance drow of 2 m 2 and elements in the last columns, is a minimum interrow distance d"n (2J For example, if R=0, the minimum inter-row distance is 192, as indicated by reference numeral 401. If R=64 the minimum inter-row distance is 288, as indicated by reference numeral 402. If R=96 the minimum inter-row distance is 320, as indicated by reference numeral 403. In the same manner, Eq. can be derived when J=l.

\\melb_files\home$\Priyanka\Keep\speci\P51504 DIV.doc 2/12/03 10 Table 2 below illustrates changes in the interleaver parameters J and R, the intra-row distance dinra, the minimum inter-row distance and the minimum inter-read address distance dmin as m increases, with respect to six encoder packet (EP) sizes as described in the IS-2000 specification, Release C.

\\melb-files\home$Priyanka\Keep\speci\PS1504 DIV.doc 2/12/03 11 Table 2 N m J R dint. dter dintra dterI d m in n(d m in 3 51 0 8 396 388 8 400 4 25 8 16 388 372 16 392 408 5 12 24 32 368 336 32 376 6 6 24 64 288 224 64 344 7 3 24 128 192 64 128 280 8 1 152 256 64 192 64 4 49 8 16 772 756 16 776 24 24 32 752 720 32 760 792 6 12 24 64 672 608 64 728 7 6 24 128 576 448 128 664 8 3 24 256 384 128 256 536 9 1 280 512 128 384 128 104 48 24 32 1520 1488 32 1528 6 24 24 64 1440 1376 64 1496 1560 7 12 24 128 1344 1216 128 1432 8 6 24 256 1152 896 256 1304 9 3 24 512 768 256 512 1048 1 536 1024 256 768 256 232 6 36 24 64 2208 2144 64 2264 7 18 24 128 2112 1984 128 2200 2328 8 9 24 256 1920 1664 256 2072 9 4 280 512 1664 1152 512 1816 2 280 1024 512 512 512 232 11 1 280 2048 512 1536 512 512 6 48 24 64 2976 2912 64 3032 7 24 24 128 2880 2752 128 2968 3096 8 12 24 256 2688 2432 256 2840 9 6 24 512 2304 1792 512 2584 3 24 1024 1536 512 1024 2072 1 11 1 1048 2048 512 1536 512 488 3744 3680 3800 7 30 24 128 3648 3520 128 3736 3864 1 8 24 256 3456 3200 256 3608 \\melb-files\home$\Priyanka\Keep\speci\P51504 DIV.doc 2/12/03 12 9 7 280 512 3200 2688 512 3352 3 792 1024 2560 1536 1024 2840 11 1 1816 2048 1024 1024 1024 1024 As described above, similarly to the case where R=0, optimal interleaver parameters are selected which maximize a minimum inter-address distance and minimize the difference between inter-address distances.

In Table 2, the minimum inter-read address distance d n in the eighth column is the smaller of the intra-row distance dintra and the minimum inter-row distance Hence, parameters that maximize the minimum inter-read address distance dmin can be obtained by selecting a row having the maximum value in the eighth column. For EP sizes of 2328 and 3864, three rows and two rows satisfy this condition. In this case, rows that satisfy another condition of minimizing the difference between inter-read address dintr must be selected. They are shown in bold and underlined in Table 2. The validity of this condition is apparent by comparing the rows having the maximum d" i n in terms of n(dmin) in the last column. Here, n(dmin) indicates the number of address pairs having a minimum inter-address distance d m Rows marked in bold and underlined in Table 2 satisfy the above two conditions for selecting optimal interleaver parameters. As noted, once the second condition is satisfied, the first condition is naturally satisfied. For reference, it is made clear that the intra-row distances dintra and the minimum inter-rdw distances listed in Table 2 are equal to those computed on P-BRO-interleaved read addresses. Table 2 covers both cases of dividing N by 2m or J with no remainder and of dividing N by 2m or J with a remainder R N=2mxJ+R Here, interleaver parameters shown in bold and underlined are optimal for each EP size.

When N=2 m x(J-1)+R (0R<2 m that is, N is divided by 2 m or J either with no remainder or with a remainder R, optimal interleaver parameters for each interleaver size N are listed in Table 3. The description made in the context of J is also applied when J is replaced by \\melbfiles\homeS\Priyanka\Keep\speci\PSo4 DIV.doc 2/12/03 13 Table 3 N m J R 408 7 4 24 792 8 4 24 1560 9 4 24 2328 10 3 280 3096 10 4 24 3864 11 2 1816 The above description has provided a method of selecting interleaver parameters expected to offer the best performance when, for example, a channel interleaver built in accordance with the IS-2000 Release A/B specification, and a subblock channel interleaver built in accordance with the IS-2000 Release C specification are used.

As described above, the optimal interleaver parameters are those that maximize an inter-address distance and at the same time, minimize the difference between inter-address distances when generating read addresses in a channel interleaver. Consequently, interleaver parameters for sub-block channel interleaving in circumstances wherein a sub-block channel interleaver is built in accordance with the IS-2000 Release C specification are values in the rows in bold and underlined in Table 2. While interleaver parameters selection has been described for the sub-block channel interleaver built in accordance with the IS-2000 Release C specification, it is obvious that the same thing can also be applied to systems of other standards.

Fig. 6 is a flowchart illustrating an optimal interleaver parameters determining operation according to an embodiment of the present invention.

Particularly, this operation is concerned with the computation of dintra dinte An optimal J) that minimizes dintr -d is selected by computing di.tr, d ,in changing J).

Referring to Fig. 6, when an interleaver size N, and parameters m and J are given in step 601, a parameter R is calculated by subtracting 2 m xJ from N in step 603.

In step 605, it is determined whether J is 1. This is a determination, therefore, of whether an interleaving matrix has a single column or not. If J is 1, the procedure goes to step 607 ("Yes" path from decision step 605) and ifJ is not 1, the procedure goes to \\melbfile\homeS\Priyanka\Reep\speci\P51504 DIV.doc 2/12/03 14 step 621 path from decision step 605) In step 607, it is determined whether R is whether N is an integer multiple of 2m). On the contrary, if R is 0 path from decision step 607) an intra-row distance dinta is set to 0 in step 609. IfR is not 0 path from decision step 607), dintr is set to 2m in step 617.

After dintra is determined, it is determined whether R is less than 3x2m-2 in step 611. If R is less than 3x2 m 2 ("Yes" path from decision step 611) a minimum interrow distance is set to 2m 2 in step 613. IfR is equal to or greater than 3x2 m 2 path from decision step 611) is set to 2m-1 in step 619. After d" is determined, d,,itr d,,r is calculated in step 615.

Meanwhile, ifJ is not 1 in step 605, dinta is set to 2m in step 621 and it is determined whether R is less than 2 m in step 623. IfR is less than 2 m ("Yes" path from decision step 623) di," is set to (2J-3)x2 m l in step 625 and then the procedure goes to step 615. If R is equal to or greater than 2 m 1 path from decision step 623), it is determined whether R is less than 3x2" 2 in step 627. IfR is less than 3x2 m 2 ("Yes" path from decision step 627), d" is set to (4J-3)x2 m 2 in step 629. IfR is equal to or greater than 3x2 m 2 path from decision step 627), is set to (2J-1)x2 m 1 in step 631 and then the procedure goes to step 615.

Optimal interleaver parameters m and J are achieved for a given N by computing dintra dr changing IfJ is one of 1, 2 and 3, a logical formula that facilitates selection of J without the repeated computation can be derived.

With a description of a logical equation deriving procedure omitted, the logical equation is \\melb-files\home$\Priyanka\Keep\peci\P51504 DIV.doc 2/12/03 15 If log 2 N- log 2 N log, 3-1 0.5849625, For 2[L'8uNJ <N<1.2 -'o,82j, J=3, {4} For I 2

L'

t og NJ N 3 2 L og u J, J 2, 2) For(3-.2 l og Nj <N<2.2

L

i og2NJ J=l.

Else if logN [log N] log 2 3 -1 0.5849625, Forl-2Io8

N

j (3J 2

[I

lo 2N J J=2, 2) For (3 2 [gN <N 2 [og,NJ, J=3, For 7 2Log2Nj N 2 -2Log2NJ, J 1.

\4 (7) From an optimal J from Eq. an optimal m is calculated by m= [log2 (8) The selection of optimal interleaver parameters by the simple logical equations is summarized below and illustrated in Fig. 7.

1. An optimal J is obtained by Eq. for a given N; and 2. m is calculated by computing Eq. using N and J.

Fig. 7 is a flowchart illustrating an optimal interleaver parameters determining operation according to another embodiment of the present invention.

Referring to Fig. 7, when N is given, a variable a is calculated by log 2 N- log N] and a variable P is calculated by 2Lo NJ in step 701. Decision step 703, determines whether a is less than a first threshold, 0.5849625. If a is less than the first threshold ("Yes" path from decision step 703), another decision is made, whether N is less than 3 in decision step 705. If N is equal to or greater than P path from \\melb_files\home$\Priyanka\Keep\speci\P51504 DIV.doc 2/12/03 16 decision step 705), the procedure goes to step 707. On the contrary, if N is less than 13 ("Yes" path from decision step 705), J is determined to be 3 in step 713.

Meanwhile, decision step 707 determines whether N is less than (3/2)x13. If S N is less than (3/2)x13 ("Yes" path from decision step 707) J is determined to be 2 in step 711. Otherwise, J is determined to be 1 in step 709 path from decision step 707).

If a is equal to or greater than the first threshold in step 703 path from decision step 703), a decision is made whether N is less than (3/2)x13 in decision step 717. If N is less than (3/2)x3 ("Yes" path from decision step 717), J is determined tobe 2 in step 721. Otherwise, decision step 719 determines whether N is less than (7/4)x3.

If N is less than (7/4)x13 ("Yes" path from decision step 719), J is determined to be 3 in step 723. Otherwise, J is determined to be 1 in step 725 path from decision step 719).

As described above, optimal m and J can be calculated simply by the logical equations using N. The optimal m and J are equal to m and J resulting from repeated computation using different J) values as illustrated in Table 2. This obviates the need for storing optimal m and J values according to N values.

When N=2328, for example, optimal m and J values are calculated in the procedure illustrated in Fig. 7 or by Eq. to Eq. as follows.

a log 2 N -[log 2 NJ log 2 2328 -Llog 2 2328]= 11.1848753-11 0.1848753.

,8 2L-og, vJ 2 Log2 2328J 211 2048.

a 0.5849625 and 83 2048 N 2328 38 3072. Thus J 2.

2 0 2 (2318)j log 2 1164]J 10, R =N =2328 -2'0 .2 =280.

For reference, Eq. is derived as follows.

In each case depicted in Fig. 6, Eq. and Eq. dinra is determined by A. When J=l, A-1. If R=O, dintra -mdnZen= 2 m 2 2m-2 \\melb_files\home$\Priyanka\Keep\speci\P51504 DIV.doc 2/12/03 17 A-2. If O<R<3.2m 2 Id di n =r 2=I 1= 3.2m2 A-3. If 3.2 m- 2 R<2m, d -d =min 2m- 2m-1 =2m-1 B. When J+l, B-i. If 0R<2m 1 Idia di;:mI 2m -(2J 2m1' 12J 51. 2m-J B ImR<2m Id a linter B-2. If intra _d min 2m -(4J 3).2 m-2 14J 71.2 -2-2 B-3. If 3.2m-2 kR<2m, d m- din2m 2" (2J 1).2m-2 2 Since N2 m J+R and O R<2 m J.2 m m When this is divided by J and then subject to a log base 2 operation, M 10 2 (<gN)<0 2 J+1.2m=M+g(1021+1 <m Thus, m I1 2 I(N) Using m =1 J can be expressed as a function of N for all the cases of A and B.

When since m [log 2 NJ, R N-2" N 2L'012 J Then the cases A-i, A-2 and A-3 can be expressed as functions of N. It therefore- follows that: 1: If N 2 L'092 NJ ditr 2m- L[092 NJ Iinterl If 2 1'ogzNJ 5N<(Z.

2 LO2NJ, I intr d 3).

2 L'092 NJ Llog, NJLlog: NJ mi If 2 J N 2 l 2 dN td =nr 2 Li092 NJ 4 2ne When J#1, since m g(N R=N-J2 =R N=--J*2"2 Then the cases B-I, B-2 and B-3 can be expressed as functions of N instead of R.

Therefore, 1: If J .21 N Iog Idinfra dinter I 1i 2 .21 \\melb-filea\home$\Priyanka\Keep\speci\P51504 DIV.doc 2/12/03 18 If J N<J 3).

2 1102 dintra J- tis(JJ -~J 44 d intra -dint:j=li 2 1 [o{ IfN JN+ .L2og1NJ da -d21 ;:r2 in2 Itra -d I 2 NJ When J=3, 1-1:2Log N I [log 2 NJ- 2, if log 2 N -dlog 2 NJ <log 2 3-1 in K3j /log 2 NJ-, otherwise if logN -log 2 NJ <log 2 0.5849625I, -2:If 2 gNJ<N 2 [log2N, Intr dr lNJ 4 i nter 1d I 8 If (1 2 'Iog2NJ N 2 [fogNJ, I -di d min I. 2logNJ 2 iner 4 When J=3, 1 If( [1l 2 NJ N [lo N-NJd lo2NJ if 1og 2 N-[log 2 NJ <log 2 3 5849625, If .2 l[lgNJ N<(i 2Log:2NJ In -d n 2L: 4 8 inter I= 8Z~iglN B If .2 Ll-gz NJ N 15) .2L'92 NJ Iditr -dmn 5 2Llg NJ If 15) 4[lg, NJ N 2 110 2 Nj, itr d in 3.2 -g2N 2 4) iner 8 \\melb_files\home$\Priyanka\Keep\speci\P51504 DIV.doc 2/12/03 19 If I 2 1og,' NJ <N o NJ, dintra -dm"l -42Lt on inter 4 If J is 4 or more, this case is neglected because dintra di", cannot be less that di,,ra in any of the cases where J=l, 2, and 3.

Eq. is obtained by selecting a case having a minimum dintr d," among the cases ofA'-l, and Similarly, Eq. is obtained by selecting a case having a minimum intra, di,'" among the cases of and In accordance with the embodiments of the present invention as described above, interleaver parameters m and J are simply optimized accoiding to an interleaver size N, for P-BRO interleaving.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

\\melb_filea\homeS\Priyanka\Keep\speci\P51504 DIV.doc 2/12/03

Claims (7)

1. A method of determining interleaver parameters m and J according to an interleaver size N to sequentially store input data in a memory to be arranged in 2 m rowx(J-l) column matrix structure and partial-bit reversal order (P-BRO) interleaving the stored data, the parameters N, m, J, and remainder R being expressed as N=2 m xJ+R (0<R<2 m the method comprising: calculating a first variable a by log 2N l O g NJ) and a second variable pby (2'log NJ); 0 comparing the first variable with a selected first threshold; comparing the interleaver size N with at least one predetermined second threshold determined by a ratio of the second variable; determining a first parameter J according to the comparison results; and L 2 N log 2 determining a second parameter m by J.

2. The method of claim 1, wherein the first parameter J is determined according to the following Equation. If log 2 N Llog, N< log, 3 -1 0.5849625, For 3 1 2 lo g 2 J N 1 2 [logNJ, J=3, (4) For(l2LogN j N< 2 Lg NJ, J 2, For 3 2 g J N<2N .2og"J, J=1. 2 2 Else if log 2 N Llog, NJ log, 3-1= 0.5849625, For I 2 L 9 2 o NJ<cN< (3 -P J 2, For (3 2 Log 2 NJ N< 2 LlogNJ, 2 4LogN J=3, For 7 2 L[ogNJ N<2 2 og 2 N J, J=l. 4)

3. The method of claim 1 or 2, wherein the parameters N, m, J, and R are determined to be H:\angelal\keep\Amended Pages 2003268814.doc 20/06/05 21 N m J+1 R 408 7 4 24 792 8 4 24 1560 9 4 24 2328 10 3 280 3096 10 4 24 3864 11 2 1816

4. An interleaver for use in a communication system, comprising: a memory having a rowxcolumn matrix; and an address generator adapted to, in use, partial-bit reversal order (P- BRO) interleave addresses of the memory, calculate a first variable a by )l2NLog2N J using a given interleaver size N and a second variable P by 2 LO 2 NJ), compare the first variable with a predetermined first threshold, compare the interleaver size N with at least one predetermined second threshold determined by a ratio of the second variable, determine a first parameter J according to the comparison log 2 results, calculate a second parameter m by L i, calculate a third parameter R by N=2mxJ+R, sequentially arrange by columns an input data stream of size N in a matrix having 2m rows and columns, and in R rows in a Jth column (0<R<2 m P-BRO interleave the arranged data and generate read addresses for reading the interleaved data by rows.

The interleaver of claim 4, wherein the parameters N, m, J, and R are determined by N m J+1 R 408 7 4 24 792 8 4 24 1560 9 4 24 2328 10 3 280 3096 10 4 24 3864 11 2 1816

6. The method of anyone of claims 1 to 3, herein described with reference to the accompanying drawings. and substantially as H:\angelal\keep\Amended Pages 2003268814.doc 20/06/05 22

7. The interleaver of claim 4 or claim 5, and substantially as herein described with reference to the accompanying drawings. Dated this 2nd day of December 2003 SAMSUNG ELECTRONICS CO LTD By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia \\melb_files\home$\Priyanka\Keep\apeci\PS1504 DIV.doc 2/12/03