Abstract:
Time and frequency de-interleaving of interleaved data in an Integrated Services Digital Broadcasting Terrestrial (ISDB-T) receiver includes exactly one random access memory (RAM) buffer in the ISDB-T receiver that performs both time and frequency de-interleaving of the interleaved data and a buffer address calculation module for generating buffer address in the buffer. The system performs memory sharing of the time and frequency de-interleaver for ISDB-T receivers and reduces the memory size required for performing de-interleaving in an ISDB-T receiver and combines the frequency and time de-interleaver buffers into one RAM thereby reducing the memory size.

Description:
BACKGROUND 
     1. Technical Field 
     The embodiments herein generally relate to communication systems, and more particularly to the field of interleaving data in orthogonal frequency division multiplexing (OFDM) communication systems. 
     2. Description of the Related Art 
     An Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) transmitter employs frequency interleaving to randomize burst error, occurring in the frequency domain, which is mainly caused by multipath distortion or carrier interference. An ISDB-T transmitter employs time interleaving to randomize burst error occurring in the time domain, which is mainly caused by impulse noise or fading interference. Time and frequency interleaving operates on the sequence of I/Q-mapped data carrier values (for the given modulation system) that constitute one OFDM symbol. The interleaved OFDM symbols are used to form an OFDM frame. 
     For performing frequency and time interleaving, existing ISDB-T receiver architectures use either two separate random access memories (RAMs) for the de-interleavers or a bank of flip-flops for the frequency de-interleaver and a RAM for the time de-interleaver. The total memory size required for frequency de-interleaving is (2×n c ×n s ) words, where n c  is the number of data carriers per one data segment and n s  is the number of data segments per one OFDM symbol. The data carriers per data segment may be 96, 192 or 384 depending on the system mode; mode  1 , mode  2  or mode  3  respectively. 
     Time de-interleaving requires a large memory owing to de-interleaver delay buffer and therefore, time de-interleaver designs are RAM based. In RAM based designs, implementation of large number of memory pointers may lead to large number of counters. Such counters are generally implemented as flip-flops leading to a larger de-interleaver area and thereby greater power consumption. 
     SUMMARY 
     In view of the foregoing, an embodiment herein provides a system for performing time and frequency de-interleaving of interleaved data in ISDB-T receiver, where wherein the system reduces a memory built-in self test (BIST) area in the receiver, the system comprising of exactly one RAM buffer, which may be either static random access memory (SRAM) or dynamic random access memory (DRAM), and is adapted to write incoming data carriers out of order and read out the data carriers in order, in the ISDB-T receiver and is adapted to perform both time and frequency de-interleaving of the interleaved data; and a buffer address calculation module for generating buffer address in the buffer, where the module increases the size of each time de-interleaver buffer by two. 
     Another embodiment provides a method of performing time and frequency de-interleaving of interleaved data in an ISDB-T receiver, the method comprising of de-interleaving the interleaved data in both time and frequency domain using exactly one RAM buffer, comprising of either a SRAM or a DRAM; and generating a buffer address in the RAM buffer using a buffer address calculation module, where the module increases size of each time de-interleaver buffer by two. Data is written into the buffer out of order and read from the buffer in order. 
     Another embodiment provides an ISDB-T receiver, wherein a memory BIST area in the receiver is reduced, the receiver comprising of exactly one RAM buffer, which can be either SRAM or DRAM, and is adapted to write incoming data carriers out of order and read out the data carriers in order, in the ISDB-T receiver and is adapted to perform both time and frequency de-interleaving of the interleaved data; and a buffer address calculation module for generating buffer address in the buffer, where the module increases the size of each time de-interleaver buffer by two. 
     These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments herein will be better understood from the following detailed description with reference to the drawings, in which: 
         FIG. 1A  illustrates the symbol alignment before interleaving for a mode  1 ,  3  segment case according to an embodiment herein; 
         FIG. 1B  illustrates the symbol alignment after interleaving for a mode  1 ,  3  segment case according to an embodiment herein; 
         FIG. 2  illustrates intra-segment rotation for a mode  1 ,  3  segment case according to an embodiment herein; 
         FIG. 3  illustrates intra-segment carrier randomization for a mode  1 ,  3  segment case according to an embodiment herein; 
         FIG. 4  illustrates a time de-interleaver buffer structure according to an embodiment herein; 
         FIG. 5  is a block diagram of a de-interleaving apparatus according to an embodiment herein; 
         FIG. 6  is a schematic diagram of a receiver according to an embodiment herein; and 
         FIG. 7  is a flow diagram illustrating a method according to an embodiment herein. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein. 
     The embodiments herein achieve a reduction in the memory required for performing de-interleaving in an ISDB-T receiver by combining the frequency and time de-interleaver buffers into one RAM. Referring now to the drawings, and more particularly to  FIGS. 1A through 7 , where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments. 
     The frequency de-interleaver has two memory locations for each carrier value within an OFDM symbol. While the current half of the memory is being written, the previous half of the memory is being read. This is equivalent to having a delay buffer of depth 2 for each carrier in an OFDM symbol; i.e., a total of n c ×n s  2-word delay buffers. At the same time the time de-interleaver also has n c ×n s  delay buffers, where n c ×n s  is divisible by 96, and the basic 96-buffer structure shown in Table 1, which is repeated several times to form n c ×n s  buffers. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Buffer size and address lookup table 
               
             
          
           
               
                 BUFFER 
                 BUFFER SIZE 
                 BUFFER ADDRESS 
               
               
                 INDEX 
                 for interleaving length I = 
                 for interleaving length I = 
               
             
          
           
               
                 I 
                 1 
                 2 
                 4 
                 8 
                 16 
                 1 
                 2 
                 4 
                 8 
                 16 
               
               
                   
               
             
          
           
               
                 0 
                 95 
                 190 
                 380 
                 760 
                 1520 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 1 
                 90 
                 180 
                 360 
                 720 
                 1440 
                 95 
                 190 
                 380 
                 760 
                 1520 
               
               
                 2 
                 85 
                 170 
                 340 
                 680 
                 1360 
                 185 
                 370 
                 740 
                 1480 
                 2960 
               
               
                 3 
                 80 
                 160 
                 320 
                 640 
                 1280 
                 270 
                 540 
                 1080 
                 2160 
                 4320 
               
               
                 4 
                 75 
                 150 
                 300 
                 600 
                 1200 
                 350 
                 700 
                 1400 
                 2800 
                 5600 
               
               
                 5 
                 70 
                 140 
                 280 
                 560 
                 1120 
                 425 
                 850 
                 1700 
                 3400 
                 6800 
               
               
                 6 
                 65 
                 130 
                 260 
                 520 
                 1040 
                 495 
                 990 
                 1980 
                 3960 
                 7920 
               
               
                 7 
                 60 
                 120 
                 240 
                 480 
                 960 
                 560 
                 1120 
                 2240 
                 4480 
                 8960 
               
               
                 8 
                 55 
                 110 
                 220 
                 440 
                 880 
                 620 
                 1240 
                 2480 
                 4960 
                 9920 
               
               
                 9 
                 50 
                 100 
                 200 
                 400 
                 800 
                 675 
                 1350 
                 2700 
                 5400 
                 10800 
               
               
                 10 
                 45 
                 90 
                 180 
                 360 
                 720 
                 725 
                 1450 
                 2900 
                 5800 
                 11600 
               
               
                 11 
                 40 
                 80 
                 160 
                 320 
                 640 
                 770 
                 1540 
                 3080 
                 6160 
                 12320 
               
               
                 12 
                 35 
                 70 
                 140 
                 280 
                 560 
                 810 
                 1620 
                 3240 
                 6480 
                 12960 
               
               
                 13 
                 30 
                 60 
                 120 
                 240 
                 480 
                 845 
                 1690 
                 3380 
                 6760 
                 13520 
               
               
                 14 
                 25 
                 50 
                 100 
                 200 
                 400 
                 875 
                 1750 
                 3500 
                 7000 
                 14000 
               
               
                 15 
                 20 
                 40 
                 80 
                 160 
                 320 
                 900 
                 1800 
                 3600 
                 7200 
                 14400 
               
               
                 16 
                 15 
                 30 
                 60 
                 120 
                 240 
                 920 
                 1840 
                 3680 
                 7360 
                 14720 
               
               
                 17 
                 10 
                 20 
                 40 
                 80 
                 160 
                 935 
                 1870 
                 3740 
                 7480 
                 14960 
               
               
                 18 
                 5 
                 10 
                 20 
                 40 
                 80 
                 945 
                 1890 
                 3780 
                 7560 
                 15120 
               
               
                 19 
                 0 
                 0 
                 0 
                 0 
                 0 
                 950 
                 1900 
                 3800 
                 7600 
                 15200 
               
               
                 20 
                 91 
                 182 
                 364 
                 728 
                 1456 
                 950 
                 1900 
                 3800 
                 7600 
                 15200 
               
               
                 21 
                 86 
                 172 
                 344 
                 688 
                 1376 
                 1041 
                 2082 
                 4164 
                 8328 
                 16656 
               
               
                 22 
                 81 
                 162 
                 324 
                 648 
                 1296 
                 1127 
                 2254 
                 4508 
                 9016 
                 18032 
               
               
                 23 
                 76 
                 152 
                 304 
                 608 
                 1216 
                 1208 
                 2416 
                 4832 
                 9664 
                 19328 
               
               
                 24 
                 71 
                 142 
                 284 
                 568 
                 1136 
                 1284 
                 2568 
                 5136 
                 10272 
                 20544 
               
               
                 25 
                 66 
                 132 
                 264 
                 528 
                 1056 
                 1355 
                 2710 
                 5420 
                 10840 
                 21680 
               
               
                 26 
                 61 
                 122 
                 244 
                 488 
                 976 
                 1421 
                 2842 
                 5684 
                 11368 
                 22736 
               
               
                 27 
                 56 
                 112 
                 224 
                 448 
                 896 
                 1482 
                 2964 
                 5928 
                 11856 
                 23712 
               
               
                 28 
                 51 
                 102 
                 204 
                 408 
                 816 
                 1538 
                 3076 
                 6152 
                 12304 
                 24608 
               
               
                 29 
                 46 
                 92 
                 184 
                 368 
                 736 
                 1589 
                 3178 
                 6356 
                 12712 
                 25424 
               
               
                 30 
                 41 
                 82 
                 164 
                 328 
                 656 
                 1635 
                 3270 
                 6540 
                 13080 
                 26160 
               
               
                 31 
                 36 
                 72 
                 144 
                 288 
                 576 
                 1676 
                 3352 
                 6704 
                 13408 
                 26816 
               
               
                 32 
                 31 
                 62 
                 124 
                 248 
                 496 
                 1712 
                 3424 
                 6848 
                 13696 
                 27392 
               
               
                 33 
                 26 
                 52 
                 104 
                 208 
                 416 
                 1743 
                 3486 
                 6972 
                 13944 
                 27888 
               
               
                 34 
                 21 
                 42 
                 84 
                 168 
                 336 
                 1769 
                 3538 
                 7076 
                 14152 
                 28304 
               
               
                 35 
                 16 
                 32 
                 64 
                 128 
                 256 
                 1790 
                 3580 
                 7160 
                 14320 
                 28640 
               
               
                 36 
                 11 
                 22 
                 44 
                 88 
                 176 
                 1806 
                 3612 
                 7224 
                 14448 
                 28896 
               
               
                 37 
                 6 
                 12 
                 24 
                 48 
                 96 
                 1817 
                 3634 
                 7268 
                 14536 
                 29072 
               
               
                 38 
                 1 
                 2 
                 4 
                 8 
                 16 
                 1823 
                 3646 
                 7292 
                 14584 
                 29168 
               
               
                 39 
                 92 
                 184 
                 368 
                 736 
                 1472 
                 1824 
                 3648 
                 7296 
                 14592 
                 29184 
               
               
                 40 
                 87 
                 174 
                 348 
                 696 
                 1392 
                 1916 
                 3832 
                 7664 
                 15328 
                 30656 
               
               
                 41 
                 82 
                 164 
                 328 
                 656 
                 1312 
                 2003 
                 4006 
                 8012 
                 16024 
                 32048 
               
               
                 42 
                 77 
                 154 
                 308 
                 616 
                 1232 
                 2085 
                 4170 
                 8340 
                 16680 
                 33360 
               
               
                 43 
                 72 
                 144 
                 288 
                 576 
                 1152 
                 2162 
                 4324 
                 8648 
                 17296 
                 34592 
               
               
                 44 
                 67 
                 134 
                 268 
                 536 
                 1072 
                 2234 
                 4468 
                 8936 
                 17872 
                 35744 
               
               
                 45 
                 62 
                 124 
                 248 
                 496 
                 992 
                 2301 
                 4602 
                 9204 
                 18408 
                 36816 
               
               
                 46 
                 57 
                 114 
                 228 
                 456 
                 912 
                 2363 
                 4726 
                 9452 
                 18904 
                 37808 
               
               
                 47 
                 52 
                 104 
                 208 
                 416 
                 832 
                 2420 
                 4840 
                 9680 
                 19360 
                 38720 
               
               
                 48 
                 47 
                 94 
                 188 
                 376 
                 752 
                 2472 
                 4944 
                 9888 
                 19776 
                 39552 
               
               
                 49 
                 42 
                 84 
                 168 
                 336 
                 672 
                 2519 
                 5038 
                 10076 
                 20152 
                 40304 
               
               
                 50 
                 37 
                 74 
                 148 
                 296 
                 592 
                 2561 
                 5122 
                 10244 
                 20488 
                 40976 
               
               
                 51 
                 32 
                 64 
                 128 
                 256 
                 512 
                 2598 
                 5196 
                 10392 
                 20784 
                 41568 
               
               
                 52 
                 27 
                 54 
                 108 
                 216 
                 432 
                 2630 
                 5260 
                 10520 
                 21040 
                 42080 
               
               
                 53 
                 22 
                 44 
                 88 
                 176 
                 352 
                 2657 
                 5314 
                 10628 
                 21256 
                 42512 
               
               
                 54 
                 17 
                 34 
                 68 
                 136 
                 272 
                 2679 
                 5358 
                 10716 
                 21432 
                 42864 
               
               
                 55 
                 12 
                 24 
                 48 
                 96 
                 192 
                 2696 
                 5392 
                 10784 
                 21568 
                 43136 
               
               
                 56 
                 7 
                 14 
                 28 
                 56 
                 112 
                 2708 
                 5416 
                 10832 
                 21664 
                 43328 
               
               
                 57 
                 2 
                 4 
                 8 
                 16 
                 32 
                 2715 
                 5430 
                 10860 
                 21720 
                 43440 
               
               
                 58 
                 93 
                 186 
                 372 
                 744 
                 1488 
                 2717 
                 5434 
                 10868 
                 21736 
                 43472 
               
               
                 59 
                 88 
                 176 
                 352 
                 704 
                 1408 
                 2810 
                 5620 
                 11240 
                 22480 
                 44960 
               
               
                 60 
                 83 
                 166 
                 332 
                 664 
                 1328 
                 2898 
                 5796 
                 11592 
                 23184 
                 46368 
               
               
                 61 
                 78 
                 156 
                 312 
                 624 
                 1248 
                 2981 
                 5962 
                 11924 
                 23848 
                 47696 
               
               
                 62 
                 73 
                 146 
                 292 
                 584 
                 1168 
                 3059 
                 6118 
                 12236 
                 24472 
                 48944 
               
               
                 63 
                 68 
                 136 
                 272 
                 544 
                 1088 
                 3132 
                 6264 
                 12528 
                 25056 
                 50112 
               
               
                 64 
                 63 
                 126 
                 252 
                 504 
                 1008 
                 3200 
                 6400 
                 12800 
                 25600 
                 51200 
               
               
                 65 
                 58 
                 116 
                 232 
                 464 
                 928 
                 3263 
                 6526 
                 13052 
                 26104 
                 52208 
               
               
                 66 
                 53 
                 106 
                 212 
                 424 
                 848 
                 3321 
                 6642 
                 13284 
                 26568 
                 53136 
               
               
                 67 
                 48 
                 96 
                 192 
                 384 
                 768 
                 3374 
                 6748 
                 13496 
                 26992 
                 53984 
               
               
                 68 
                 43 
                 86 
                 172 
                 344 
                 688 
                 3422 
                 6844 
                 13688 
                 27376 
                 54752 
               
               
                 69 
                 38 
                 76 
                 152 
                 304 
                 608 
                 3465 
                 6930 
                 13860 
                 27720 
                 55440 
               
               
                 70 
                 33 
                 66 
                 132 
                 264 
                 528 
                 3503 
                 7006 
                 14012 
                 28024 
                 56048 
               
               
                 71 
                 28 
                 56 
                 112 
                 224 
                 448 
                 3536 
                 7072 
                 14144 
                 28288 
                 56576 
               
               
                 72 
                 23 
                 46 
                 92 
                 184 
                 368 
                 3564 
                 7128 
                 14256 
                 28512 
                 57024 
               
               
                 73 
                 18 
                 36 
                 72 
                 144 
                 288 
                 3587 
                 7174 
                 14348 
                 28696 
                 57392 
               
               
                 74 
                 13 
                 26 
                 52 
                 104 
                 208 
                 3605 
                 7210 
                 14420 
                 28840 
                 57680 
               
               
                 75 
                 8 
                 16 
                 32 
                 64 
                 128 
                 3618 
                 7236 
                 14472 
                 28944 
                 57888 
               
               
                 76 
                 3 
                 6 
                 12 
                 24 
                 48 
                 3626 
                 7252 
                 14504 
                 29008 
                 58016 
               
               
                 77 
                 94 
                 188 
                 376 
                 752 
                 1504 
                 3629 
                 7258 
                 14516 
                 29032 
                 58064 
               
               
                 78 
                 89 
                 178 
                 356 
                 712 
                 1424 
                 3723 
                 7446 
                 14892 
                 29784 
                 59568 
               
               
                 79 
                 84 
                 168 
                 336 
                 672 
                 1344 
                 3812 
                 7624 
                 15248 
                 30496 
                 60992 
               
               
                 80 
                 79 
                 158 
                 316 
                 632 
                 1264 
                 3896 
                 7792 
                 15584 
                 31168 
                 62336 
               
               
                 81 
                 74 
                 148 
                 296 
                 592 
                 1184 
                 3975 
                 7950 
                 15900 
                 31800 
                 63600 
               
               
                 82 
                 69 
                 138 
                 276 
                 552 
                 1104 
                 4049 
                 8098 
                 16196 
                 32392 
                 64784 
               
               
                 83 
                 64 
                 128 
                 256 
                 512 
                 1024 
                 4118 
                 8236 
                 16472 
                 32944 
                 65888 
               
               
                 84 
                 59 
                 118 
                 236 
                 472 
                 944 
                 4182 
                 8364 
                 16728 
                 33456 
                 66912 
               
               
                 85 
                 54 
                 108 
                 216 
                 432 
                 864 
                 4241 
                 8482 
                 16964 
                 33928 
                 67856 
               
               
                 86 
                 49 
                 98 
                 196 
                 392 
                 784 
                 4295 
                 8590 
                 17180 
                 34360 
                 68720 
               
               
                 87 
                 44 
                 88 
                 176 
                 352 
                 704 
                 4344 
                 8688 
                 17376 
                 34752 
                 69504 
               
               
                 88 
                 39 
                 78 
                 156 
                 312 
                 624 
                 4388 
                 8776 
                 17552 
                 35104 
                 70208 
               
               
                 89 
                 34 
                 68 
                 136 
                 272 
                 544 
                 4427 
                 8854 
                 17708 
                 35416 
                 70832 
               
               
                 90 
                 29 
                 58 
                 116 
                 232 
                 464 
                 4461 
                 8922 
                 17844 
                 35688 
                 71376 
               
               
                 91 
                 24 
                 48 
                 96 
                 192 
                 384 
                 4490 
                 8980 
                 17960 
                 35920 
                 71840 
               
               
                 92 
                 19 
                 38 
                 76 
                 152 
                 304 
                 4514 
                 9028 
                 18056 
                 36112 
                 72224 
               
               
                 93 
                 14 
                 28 
                 56 
                 112 
                 224 
                 4533 
                 9066 
                 18132 
                 36264 
                 72528 
               
               
                 94 
                 9 
                 18 
                 36 
                 72 
                 144 
                 4547 
                 9094 
                 18188 
                 36376 
                 72752 
               
               
                 95 
                 4 
                 8 
                 16 
                 32 
                 64 
                 4556 
                 9112 
                 18224 
                 36448 
                 72896 
               
               
                   
               
             
          
         
       
     
     The frequency de-interleaver delay buffers are written out-of-order and read in order, the frequency de-interleaver output feeds the time de-interleaver, and therefore the time de-interleaver buffers are written and read in order. Therefore, the corresponding frequency and time de-interleaver buffers can be combined into one RAM. Due to the combination of the buffers, each of the time de-interleaver buffers grows by two locations. The combined architecture operates similar to the original time de-interleaver design, except that the incoming carriers are written to the delay buffers out-of-order and the buffer address calculation logic adds 2 to the size of each buffer. The combined buffer size and address lookup table are provided in Table 2, which shows the resulting combined frequency and time de-interleaver buffer structure. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Combined buffer size and address lookup table 
               
             
          
           
               
                   
                 Combined size 
                 Combined address 
               
               
                   
                 I 
                 I 
               
             
          
           
               
                 Buffer 
                 0 
                 1 
                 2 
                 4 
                 8 
                 0 
                 1 
                 2 
                 4 
                 8 
               
               
                   
               
             
          
           
               
                 0 
                 2 
                 97 
                 192 
                 382 
                 762 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 1 
                 2 
                 92 
                 182 
                 362 
                 722 
                 2 
                 97 
                 192 
                 382 
                 762 
               
               
                 2 
                 2 
                 87 
                 172 
                 342 
                 682 
                 4 
                 189 
                 374 
                 744 
                 1484 
               
               
                 3 
                 2 
                 82 
                 162 
                 322 
                 642 
                 6 
                 276 
                 546 
                 1086 
                 2166 
               
               
                 4 
                 2 
                 77 
                 152 
                 302 
                 602 
                 8 
                 358 
                 708 
                 1408 
                 2808 
               
               
                 5 
                 2 
                 72 
                 142 
                 282 
                 562 
                 10 
                 435 
                 860 
                 1710 
                 3410 
               
               
                 6 
                 2 
                 67 
                 132 
                 262 
                 522 
                 12 
                 507 
                 1002 
                 1992 
                 3972 
               
               
                 7 
                 2 
                 62 
                 122 
                 242 
                 482 
                 14 
                 574 
                 1134 
                 2254 
                 4494 
               
               
                 8 
                 2 
                 57 
                 112 
                 222 
                 442 
                 16 
                 636 
                 1256 
                 2496 
                 4976 
               
               
                 9 
                 2 
                 52 
                 102 
                 202 
                 402 
                 18 
                 693 
                 1368 
                 2718 
                 5418 
               
               
                 10 
                 2 
                 47 
                 92 
                 182 
                 362 
                 20 
                 745 
                 1470 
                 2920 
                 5820 
               
               
                 11 
                 2 
                 42 
                 82 
                 162 
                 322 
                 22 
                 792 
                 1562 
                 3102 
                 6182 
               
               
                 12 
                 2 
                 37 
                 72 
                 142 
                 282 
                 24 
                 834 
                 1644 
                 3264 
                 6504 
               
               
                 13 
                 2 
                 32 
                 62 
                 122 
                 242 
                 26 
                 871 
                 1716 
                 3406 
                 6786 
               
               
                 14 
                 2 
                 27 
                 52 
                 102 
                 202 
                 28 
                 903 
                 1778 
                 3528 
                 7028 
               
               
                 15 
                 2 
                 22 
                 42 
                 82 
                 162 
                 30 
                 930 
                 1830 
                 3630 
                 7230 
               
               
                 16 
                 2 
                 17 
                 32 
                 62 
                 122 
                 32 
                 952 
                 1872 
                 3712 
                 7392 
               
               
                 17 
                 2 
                 12 
                 22 
                 42 
                 82 
                 34 
                 969 
                 1904 
                 3774 
                 7514 
               
               
                 18 
                 2 
                 7 
                 12 
                 22 
                 42 
                 36 
                 981 
                 1926 
                 3816 
                 7596 
               
               
                 19 
                 2 
                 2 
                 2 
                 2 
                 2 
                 38 
                 988 
                 1938 
                 3838 
                 7638 
               
               
                 20 
                 2 
                 93 
                 184 
                 366 
                 730 
                 40 
                 990 
                 1940 
                 3840 
                 7640 
               
               
                 21 
                 2 
                 88 
                 174 
                 346 
                 690 
                 42 
                 1083 
                 2124 
                 4206 
                 8370 
               
               
                 22 
                 2 
                 83 
                 164 
                 326 
                 650 
                 44 
                 1171 
                 2298 
                 4552 
                 9060 
               
               
                 23 
                 2 
                 78 
                 154 
                 306 
                 610 
                 46 
                 1254 
                 2462 
                 4878 
                 9710 
               
               
                 24 
                 2 
                 73 
                 144 
                 286 
                 570 
                 48 
                 1332 
                 2616 
                 5184 
                 10320 
               
               
                 25 
                 2 
                 68 
                 134 
                 266 
                 530 
                 50 
                 1405 
                 2760 
                 5470 
                 10890 
               
               
                 26 
                 2 
                 63 
                 124 
                 246 
                 490 
                 52 
                 1473 
                 2894 
                 5736 
                 11420 
               
               
                 27 
                 2 
                 58 
                 114 
                 226 
                 450 
                 54 
                 1536 
                 3018 
                 5982 
                 11910 
               
               
                 28 
                 2 
                 53 
                 104 
                 206 
                 410 
                 56 
                 1594 
                 3132 
                 6208 
                 12360 
               
               
                 29 
                 2 
                 48 
                 94 
                 186 
                 370 
                 58 
                 1647 
                 3236 
                 6414 
                 12770 
               
               
                 30 
                 2 
                 43 
                 84 
                 166 
                 330 
                 60 
                 1695 
                 3330 
                 6600 
                 13140 
               
               
                 31 
                 2 
                 38 
                 74 
                 146 
                 290 
                 62 
                 1738 
                 3414 
                 6766 
                 13470 
               
               
                 32 
                 2 
                 33 
                 64 
                 126 
                 250 
                 64 
                 1776 
                 3488 
                 6912 
                 13760 
               
               
                 33 
                 2 
                 28 
                 54 
                 106 
                 210 
                 66 
                 1809 
                 3552 
                 7038 
                 14010 
               
               
                 34 
                 2 
                 23 
                 44 
                 86 
                 170 
                 68 
                 1837 
                 3606 
                 7144 
                 14220 
               
               
                 35 
                 2 
                 18 
                 34 
                 66 
                 130 
                 70 
                 1860 
                 3650 
                 7230 
                 14390 
               
               
                 36 
                 2 
                 13 
                 24 
                 46 
                 90 
                 72 
                 1878 
                 3684 
                 7296 
                 14520 
               
               
                 37 
                 2 
                 8 
                 14 
                 26 
                 50 
                 74 
                 1891 
                 3708 
                 7342 
                 14610 
               
               
                 38 
                 2 
                 3 
                 4 
                 6 
                 10 
                 76 
                 1899 
                 3722 
                 7368 
                 14660 
               
               
                 39 
                 2 
                 94 
                 186 
                 370 
                 738 
                 78 
                 1902 
                 3726 
                 7374 
                 14670 
               
               
                 40 
                 2 
                 89 
                 176 
                 350 
                 698 
                 80 
                 1996 
                 3912 
                 7744 
                 15408 
               
               
                 41 
                 2 
                 84 
                 166 
                 330 
                 658 
                 82 
                 2085 
                 4088 
                 8094 
                 16106 
               
               
                 42 
                 2 
                 79 
                 156 
                 310 
                 618 
                 84 
                 2169 
                 4254 
                 8424 
                 16764 
               
               
                 43 
                 2 
                 74 
                 146 
                 290 
                 578 
                 86 
                 2248 
                 4410 
                 8734 
                 17382 
               
               
                 44 
                 2 
                 69 
                 136 
                 270 
                 538 
                 88 
                 2322 
                 4556 
                 9024 
                 17960 
               
               
                 45 
                 2 
                 64 
                 126 
                 250 
                 498 
                 90 
                 2391 
                 4692 
                 9294 
                 18498 
               
               
                 46 
                 2 
                 59 
                 116 
                 230 
                 458 
                 92 
                 2455 
                 4818 
                 9544 
                 18996 
               
               
                 47 
                 2 
                 54 
                 106 
                 210 
                 418 
                 94 
                 2514 
                 4934 
                 9774 
                 19454 
               
               
                 48 
                 2 
                 49 
                 96 
                 190 
                 378 
                 96 
                 2568 
                 5040 
                 9984 
                 19872 
               
               
                 49 
                 2 
                 44 
                 86 
                 170 
                 338 
                 98 
                 2617 
                 5136 
                 10174 
                 20250 
               
               
                 50 
                 2 
                 39 
                 76 
                 150 
                 298 
                 100 
                 2661 
                 5222 
                 10344 
                 20588 
               
               
                 51 
                 2 
                 34 
                 66 
                 130 
                 258 
                 102 
                 2700 
                 5298 
                 10494 
                 20886 
               
               
                 52 
                 2 
                 29 
                 56 
                 110 
                 218 
                 104 
                 2734 
                 5364 
                 10624 
                 21144 
               
               
                 53 
                 2 
                 24 
                 46 
                 90 
                 178 
                 106 
                 2763 
                 5420 
                 10734 
                 21362 
               
               
                 54 
                 2 
                 19 
                 36 
                 70 
                 138 
                 108 
                 2787 
                 5466 
                 10824 
                 21540 
               
               
                 55 
                 2 
                 14 
                 26 
                 50 
                 98 
                 110 
                 2806 
                 5502 
                 10894 
                 21678 
               
               
                 56 
                 2 
                 9 
                 16 
                 30 
                 58 
                 112 
                 2820 
                 5528 
                 10944 
                 21776 
               
               
                 57 
                 2 
                 4 
                 6 
                 10 
                 18 
                 114 
                 2829 
                 5544 
                 10974 
                 21834 
               
               
                 58 
                 2 
                 95 
                 188 
                 374 
                 746 
                 116 
                 2833 
                 5550 
                 10984 
                 21852 
               
               
                 59 
                 2 
                 90 
                 178 
                 354 
                 706 
                 118 
                 2928 
                 5738 
                 11358 
                 22598 
               
               
                 60 
                 2 
                 85 
                 168 
                 334 
                 666 
                 120 
                 3018 
                 5916 
                 11712 
                 23304 
               
               
                 61 
                 2 
                 80 
                 158 
                 314 
                 626 
                 122 
                 3103 
                 6084 
                 12046 
                 23970 
               
               
                 62 
                 2 
                 75 
                 148 
                 294 
                 586 
                 124 
                 3183 
                 6242 
                 12360 
                 24596 
               
               
                 63 
                 2 
                 70 
                 138 
                 274 
                 546 
                 126 
                 3258 
                 6390 
                 12654 
                 25182 
               
               
                 64 
                 2 
                 65 
                 128 
                 254 
                 506 
                 128 
                 3328 
                 6528 
                 12928 
                 25728 
               
               
                 65 
                 2 
                 60 
                 118 
                 234 
                 466 
                 130 
                 3393 
                 6656 
                 13182 
                 26234 
               
               
                 66 
                 2 
                 55 
                 108 
                 214 
                 426 
                 132 
                 3453 
                 6774 
                 13416 
                 26700 
               
               
                 67 
                 2 
                 50 
                 98 
                 194 
                 386 
                 134 
                 3508 
                 6882 
                 13630 
                 27126 
               
               
                 68 
                 2 
                 45 
                 88 
                 174 
                 346 
                 136 
                 3558 
                 6980 
                 13824 
                 27512 
               
               
                 69 
                 2 
                 40 
                 78 
                 154 
                 306 
                 138 
                 3603 
                 7068 
                 13998 
                 27858 
               
               
                 70 
                 2 
                 35 
                 68 
                 134 
                 266 
                 140 
                 3643 
                 7146 
                 14152 
                 28164 
               
               
                 71 
                 2 
                 30 
                 58 
                 114 
                 226 
                 142 
                 3678 
                 7214 
                 14286 
                 28430 
               
               
                 72 
                 2 
                 25 
                 48 
                 94 
                 186 
                 144 
                 3708 
                 7272 
                 14400 
                 28656 
               
               
                 73 
                 2 
                 20 
                 38 
                 74 
                 146 
                 146 
                 3733 
                 7320 
                 14494 
                 28842 
               
               
                 74 
                 2 
                 15 
                 28 
                 54 
                 106 
                 148 
                 3753 
                 7358 
                 14568 
                 28988 
               
               
                 75 
                 2 
                 10 
                 18 
                 34 
                 66 
                 150 
                 3768 
                 7386 
                 14622 
                 29094 
               
               
                 76 
                 2 
                 5 
                 8 
                 14 
                 26 
                 152 
                 3778 
                 7404 
                 14656 
                 29160 
               
               
                 77 
                 2 
                 96 
                 190 
                 378 
                 754 
                 154 
                 3783 
                 7412 
                 14670 
                 29186 
               
               
                 78 
                 2 
                 91 
                 180 
                 358 
                 714 
                 156 
                 3879 
                 7602 
                 15048 
                 29940 
               
               
                 79 
                 2 
                 86 
                 170 
                 338 
                 674 
                 158 
                 3970 
                 7782 
                 15406 
                 30654 
               
               
                 80 
                 2 
                 81 
                 160 
                 318 
                 634 
                 160 
                 4056 
                 7952 
                 15744 
                 31328 
               
               
                 81 
                 2 
                 76 
                 150 
                 298 
                 594 
                 162 
                 4137 
                 8112 
                 16062 
                 31962 
               
               
                 82 
                 2 
                 71 
                 140 
                 278 
                 554 
                 164 
                 4213 
                 8262 
                 16360 
                 32556 
               
               
                 83 
                 2 
                 66 
                 130 
                 258 
                 514 
                 166 
                 4284 
                 8402 
                 16638 
                 33110 
               
               
                 84 
                 2 
                 61 
                 120 
                 238 
                 474 
                 168 
                 4350 
                 8532 
                 16896 
                 33624 
               
               
                 85 
                 2 
                 56 
                 110 
                 218 
                 434 
                 170 
                 4411 
                 8652 
                 17134 
                 34098 
               
               
                 86 
                 2 
                 51 
                 100 
                 198 
                 394 
                 172 
                 4467 
                 8762 
                 17352 
                 34532 
               
               
                 87 
                 2 
                 46 
                 90 
                 178 
                 354 
                 174 
                 4518 
                 8862 
                 17550 
                 34926 
               
               
                 88 
                 2 
                 41 
                 80 
                 158 
                 314 
                 176 
                 4564 
                 8952 
                 17728 
                 35280 
               
               
                 89 
                 2 
                 36 
                 70 
                 138 
                 274 
                 178 
                 4605 
                 9032 
                 17886 
                 35594 
               
               
                 90 
                 2 
                 31 
                 60 
                 118 
                 234 
                 180 
                 4641 
                 9102 
                 18024 
                 35868 
               
               
                 91 
                 2 
                 26 
                 50 
                 98 
                 194 
                 182 
                 4672 
                 9162 
                 18142 
                 36102 
               
               
                 92 
                 2 
                 21 
                 40 
                 78 
                 154 
                 184 
                 4698 
                 9212 
                 18240 
                 36296 
               
               
                 93 
                 2 
                 16 
                 30 
                 58 
                 114 
                 186 
                 4719 
                 9252 
                 18318 
                 36450 
               
               
                 94 
                 2 
                 11 
                 20 
                 38 
                 74 
                 188 
                 4735 
                 9282 
                 18376 
                 36564 
               
               
                 95 
                 2 
                 6 
                 10 
                 18 
                 34 
                 190 
                 4746 
                 9302 
                 18414 
                 36638 
               
               
                   
               
             
          
         
       
     
       FIGS. 1A and 1B  illustrate inter-segment interleaving for a mode  1 ,  3  segment case according to an embodiment herein.  FIGS. 1A and 1B  illustrate the interleaving operation ( FIG. 1A  is the symbol alignment before interleaving and  FIG. 1B  is the symbol alignment after interleaving), which is performed within a transmission layer containing more than one data segment; e.g., in layer B of 3-segment transmission, which contains two segments. In  FIGS. 1A and 1B  “S” represents data carriers within each segment in mode  1 . There are 96 data carriers per segment. After the interleaving, in  FIG. 1B , all even-order carriers are moved to segment number  1  and all odd-order carriers are moved to segment number  2 . The segment number  0  is not affected by the inter-segment interleaving because it belongs to the layer A, which contains only one segment. 
       FIG. 2  illustrates intra-segment rotation for a mode  1 ,  3  segment case according to an embodiment herein. In  FIG. 2  “k” is the corresponding segment number:  0 ,  1 ,  2 , etc. In this operation all data carriers within a given segment are rotated to the right within the segment by k carrier positions. The segment number  0  is not affected by the rotation operation because k=0 for this segment, which yields rotation by 0 carrier positions. 
       FIG. 3  illustrates an intra-segment randomization for a mode  1 ,  3  segment case according to an embodiment herein.  FIG. 3  illustrates an exchange of data carrier locations based on the specified randomization table. Different system modes use different randomization tables. 
       FIG. 4  illustrates a time de-interleaver buffer structure  400  according to an embodiment herein. The time domain interleaving uses a convolutional interleaving scheme, in which every data carrier in an OFDM symbol is fed into a delay buffer of depth: bi=I×((i×5) mod 96). Here “i” is the buffer index ranging from 0 to n c −1 and “i” is the interleaving length associated with a given OFDM transmission layer, which takes one of the following values: 0, 1, 2, 4, 8, or 16. The operation of the convolutional time de-interleaver in the ISDB-T receiver is the opposite in the sense that delay buffer depths are given by: b×i=I×95−I×((i×5) mod 96). There are a total of 95 distinct non-zero delay buffers sizes in the de-interleaver, regardless of the system mode, since the buffer depth pattern given by b×i=I×95−I×((i×5) mod 96) will repeat every 96 buffers, and also b×19=b×115=b×211=b×307=0, so the 19th, 115th, 211 th , and 307th data carriers in every OFDM symbol are transferred without delay. The general time de-interleaver buffer structure  400  is illustrated in  FIG. 4 , showing the first 50 buffers with the buffer depth at the beginning of the shown range bx0=95 and buffer depth at the end of this range bx49=42. Each buffer entry requires the number of bits equal to the data carrier soft decision width, therefore the total amount of memory required for the time de-interleaver is the combined depth of all the buffers multiplied by the data carrier bit width, resulting in a very large memory size since the total combined buffer depth for one segment in mode  1  is 72,960 entries for I=16. Table 3 indicates the total RAM size. 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Total RAM size 
               
               
                 TOTAL RAM SIZE FOR 1 SEGMENT IN MODE 1 
               
               
                 for interleaving length I = 
               
             
          
           
               
                 1 
                 2 
                 4 
                 8 
                 16 
               
               
                   
               
               
                 4,560 
                 9,120 
                 18,240 
                 36,480 
                 72,960 
               
               
                   
               
             
          
         
       
     
       FIG. 5  a block diagram of a de-interleaving apparatus  500  according to an embodiment herein. The apparatus  500  comprises a de-interleaving memory  501 , a controller  502 , a read/write (R/W) control logic  503 , and a buffer address generator  504 . The controller  502  comprises of R/W control logic  503  and the buffer address generator  504  embedded within. The frequency and time de-interleaver memories are combined into a single memory; i.e. the de-interleaver memory  501 . The inputs for the de-interleaving memory  501  are the generated buffer address and the data to be interleaved. The other input for the de-interleaving memory  501  is the data to be interleaved. The output from the de-interleaving memory  501  is the interleaved data. The de-interleaver memory  501  may be embodied as DRAM or SRAM. The controller  502  generates the buffer address by the buffer address generator  504 . The controller also provides the R/W control bus to the de-interleaver memory  501 . The data to be interleaved acts as an input to the de-interleaver memory  501  and is provided with buffer address by the buffer address generator  504 . During the read write operations the memory is divided into two parts. For example the frequency de-interleaver has two memory locations for each carrier value within an OFDM symbol, while the current half of the memory is being written; the previous half of the memory is being read. Thus, the R/W control bus controls the memory during the read write operations taking place in the de-interleaver memory  501 . The interleaved data is obtained as an output from the de-interleaver memory  501 . 
       FIG. 6  illustrates a schematic diagram of a receiver  600  having an a memory  602  having a computer set of instructions, a bus  604 , a display  606 , a speaker  608 , and a processor  610  capable of processing a set of instructions to perform any one or more of the methodologies herein, according to an embodiment herein. The processor  610  may also enable digital content to be consumed in the form of video for output via one or more displays  606  or audio for output via speaker and/or earphones  608 . The processor  610  may also carry out the methods described herein and in accordance with the embodiments herein. 
     Digital content may also be stored in the memory  602  for future processing or consumption. The memory  602  may also store program specific information and/or service information (PSI/SI), including information about digital content (e.g., the detected information bits) available in the future or stored from the past. A user of the receiver  600  may view this stored information on display  606  and select an item of for viewing, listening, or other uses via input, which may take the form of keypad, scroll, or other input device(s) or combinations thereof. When digital content is selected, the processor  610  may pass information. The content and PSI/SI may be passed among functions within the receiver  600  using bus  604 . 
       FIG. 7 , with reference to  FIGS. 1A through 6 , illustrates a method of performing time and frequency de-interleaving of interleaved data in an ISDB-T receiver  600 , wherein the method comprises de-interleaving ( 710 ) the interleaved data in a both time and frequency domain using exactly one RAM buffer  501  comprising of either a SRAM or a DRAM; and generating ( 720 ) a buffer address in the RAM buffer  501  using a buffer address calculation module (i.e., controller  502 ), where the module increases size of each time de-interleaver buffer by two. Data is written into the buffer  501  out of order and read from the buffer  501  in order. The embodiments herein eliminate overhead area related to the frequency de-interleaver stand-alone RAM implementation. The overhead area also includes area that is used by the memory BIST schematic. 
     The techniques provided by the embodiments herein may be implemented on an integrated circuit chip (not shown). The chip design is created in a graphical computer programming language, and stored in a computer storage medium (such as a disk, tape, physical hard drive, or virtual hard drive such as in a storage access network). If the designer does not fabricate chips or the photolithographic masks used to fabricate chips, the designer transmits the resulting design by physical means (e.g., by providing a copy of the storage medium storing the design) or electronically (e.g., through the Internet) to such entities, directly or indirectly. The stored design is then converted into the appropriate format (e.g., GDSII) for the fabrication of photolithographic masks, which typically include multiple copies of the chip design in question that are to be formed on a wafer. The photolithographic masks are utilized to define areas of the wafer (and/or the layers thereon) to be etched or otherwise processed. 
     The resulting integrated circuit chips can be distributed by the fabricator in raw wafer form (that is, as a single wafer that has multiple unpackaged chips), as a bare die, or in a packaged form. In the latter case the chip is mounted in a single chip package (such as a plastic carrier, with leads that are affixed to a motherboard or other higher level carrier) or in a multichip package (such as a ceramic carrier that has either or both surface interconnections or buried interconnections). In any case the chip is then integrated with other chips, discrete circuit elements, and/or other signal processing devices as part of either (a) an intermediate product, such as a motherboard, or (b) an end product. The end product can be any product that includes integrated circuit chips, ranging from toys and other low-end applications to advanced computer products having a display, a keyboard or other input device, and a central processor. 
     The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.