信道編碼和差錯控制ppt課件

1、混合信道混合信道 停頓等待ARQ系統(tǒng)接納數(shù)據(jù)ACKACKNAKACKACKNAKACK1233455t發(fā)送數(shù)據(jù)12334556t有錯碼組有錯碼組拉后ARQ系統(tǒng)214365798接納數(shù)據(jù)有錯碼組有錯碼組910 1110 11 12576ACK1NAK5NAK9ACK55769521436798發(fā)送數(shù)據(jù)10 1110 11 12重發(fā)碼組重發(fā)碼組選擇重發(fā)ARQ系統(tǒng)9接納數(shù)據(jù)有錯碼組有錯碼組214365759810 11131412發(fā)送數(shù)據(jù)9958521436710 1113 1412重發(fā)碼組重發(fā)碼組NAK9ACK1NAK5ACK5ACK9000 111 就能檢測兩個以下錯碼，或糾正一個錯碼。就能檢測

2、兩個以下錯碼，或糾正一個錯碼。信息位監(jiān)視位晴000云011陰101雨110k個信息位r個監(jiān)視位an-1an-2.arar-1an-2.a0t碼長 n = k + r分組碼的構(gòu)造(0,0,0)(0,0,1)(1,0,1)(1,0,0)(1,1,0)(0,1,0)(0,1,1)(1,1,1)a2a0a110 ed0123BA漢明間隔ed0碼距等于3的兩個碼組120 tdBtA漢明間隔012345td0碼距等于5的兩個碼組AB1tt漢明間隔e碼距等于(e+t+1)的兩個碼組)(10teted10-610-510-410-310-210-1編碼后Eb/n0 (dB)編碼和誤碼率關(guān)系PeCDEAB2PS

3、K10-610-510-410-310-210-1編碼后Eb/n0 (dB)編碼和誤碼率關(guān)系PeCDEAB2PSKBsssbRnPTnPnTPnE0000)/1 (10-610-510-410-310-210-1編碼后Eb/n0 (dB)編碼和誤碼率關(guān)系PeCDEAB2PSK)(/00dBnEnEGcbubdB0021aaann1021aaannjnjnjppCnjP)1 (),()!( !jnjnCnj2/1222)1 (njjnjnjuppCP2/ )1(1222)1 (njjnjnjuppCP信息位監(jiān)視位晴000云011陰101雨1102/1222)1 (njjnjnjuppCP8244

4、3242204442242212424210666126)1 (6)1 ()1 ()1 (ppppppppppCppCppCPjjjjunmnmnk)1()1(0021aaann021aaaSnn021aaaSnn021aaaSnn1212rknrr或S1 S2 S3錯碼位置S1 S2 S3錯碼位置001a0101a4010a1110a5100a2111a6011a3000無錯碼1212rknrr或24561aaaaS13562aaaaS03463aaaaS000034613562456aaaaaaaaaaaa346035614562aaaaaaaaaaaa信息位a6 a5 a4 a3監(jiān)視位a

5、2 a1 a0信息位a6 a5 a4 a3監(jiān)視位a2 a1 a0000000010001110001011100110000101011010010001111010110010100110110000101011011101010011001111101000111000111111124561aaaaS13562aaaaS03463aaaaSS1 S2 S3錯碼位置S1 S2 S3錯碼位置001a0101a4010a1110a5100a2111a6011a3000無錯碼10 ed120 td1212rrrnk000034613562456aaaaaaaaaaaa01001101001010

6、1100010111012345601234560123456aaaaaaaaaaaaaaaaaaaaa010011010010101100010111012345601234560123456aaaaaaaaaaaaaaaaaaaaa0001011001110101011101000123456aaaaaaa101100111010101110100HrPIH0011011010110110011103456012101111011110aaaaaaa346035614562aaaaaaaaaaaaQ34563456012011101110111aaaaaaaaaaa011000110100

7、1011001001111000QGkI IG34560123456aaaaaaaaaaaA0121aaaaAnn0121bbbbBnnB A = E (模2)0121eeeeEnniiiiiababe當(dāng)當(dāng), 1, 0由于線性碼具有封鎖性，所以兩個碼組由于線性碼具有封鎖性，所以兩個碼組(A1和和A2)之間之間的間隔即對應(yīng)位不同的數(shù)目必定是另一個碼組的間隔即對應(yīng)位不同的數(shù)目必定是另一個碼組(A1 + A2)的分量即的分量即“1的數(shù)目。因此，碼的最小間隔就是碼的數(shù)目。因此，碼的最小間隔就是碼的最小分量除全的最小分量除全“0碼組外。碼組外。向右移一位即得到第向右移一位即得到第7碼組。碼組。碼組編號信

8、息位監(jiān)視位碼組編號信息位監(jiān)視位A6a5a4a3a2a1a0a6a5a4A3a2a1a01000000051001011200101116101110030101110711001014011100181110010012211)(axaxaxaxTnnnn11010011)(25623456xxxxxxxxxxTnpnpQnm,)()()()(xRxQxNxF）（模)()()(xNxRxF）（模) 1(133xx）（模) 1(113224xxxxx結(jié)論：一個長為結(jié)論：一個長為n的循環(huán)碼必定為按模的循環(huán)碼必定為按模(xn + 1)運算的一個余式。運算的一個余式。）（模) 1()()(nixxTx

9、Tx012211)(axaxaxaxTnnnn)()(1102211011112211xTaxaxaxaxaxaxaxaxaxaxTxininininniniinininninni1)(256xxxxT）（模) 1()(723535893xxxxxxxxxxTxG34560123456aaaaaaaaaaaA0110001101001011001001111000QGkI I)()()()()(21xgxxgxgxxgxxkkG碼組編號信息位監(jiān)視位碼組編號信息位監(jiān)視位A6a5a4a3a2a1a0a6a5a4A3a2a1a0100000005100101120010111610111003010

10、1110711001014011100181110010)()()()(2xgxxgxgxxG001011101011101011100)(xG)()()()()()()()()()(452645262456456xgaxaxaxgaxxgaxgxaxgxxgxgxaaaxaaaxTG）（模) 1()()(nixxTxTx1)()(1)(nnkxxTxQxxTx)() 1()(xTxxTxnk)() 1()(xTxxTxnk)()(1xhxxgxkn) 1)(1)(1(13237xxxxxx1) 1)(1(2423xxxxxx1) 1)(1(2343xxxxxx)()()()()(xgxrxQ

11、xgxmxkn11) 1(1)()(24222456xxxxxxxxxxxxgxmxkn10111101111101111100000)(/)()()(/)(xgxrxQxgxR)(/ )()()(/ )(xgxrxQxgxRnktg(x)nktg(x)172123334191212222122324727166353435145664713347656573245340465244430733571076135430006717177735372PSK漢明碼(7, 4) t=1 漢明碼(31, 26) t=1擴展戈萊碼(24, 12) t=3BCH碼(127, 64) t=10Eb / n0

12、 (dB)Pe編碼輸出每次輸入k比特1k1k1k1k 1 k2k3kNk 12nNk級移存器n個模2加法器每輸入k比特旋轉(zhuǎn)1周123b3b1輸入b2編碼輸出c2c1c3321331211bbbcbbcbcb11101000b3b200011110011000c1c2 c3111110010100001011000形狀abdcbca000111001110011100010101000111001110011100010101c1c2c3000100111011001101110010c1c2c3111000001110c1c2c3信息位 1 1 0 1ba起點信息位000111c1c2c3ab

13、cdabcdabcdabcd上半部下半部10a形狀 b3b2 a 0 0 b 0 1 c 1 0 d 1 1abcdabcdcdab011001前一形狀b3 b2當(dāng)前輸入 b1輸出c1c2c3下一形狀b3 b2a (00)01000111a (00)b (01)b (01)01001110c (10)d (11)c (10)01011100a (00)b (01)d (11)01010101c (10)d (11)321331211bbbcbbcbc123b3b1輸入b2編碼輸出c2c1c3abcd000111101110010011100001110110110110011011011010

14、010010101101101001001001001abcdabcd000000000000000111111111111111100100100abcd000111101110010011100001abcdabcd110010001111100110110110110011011011010010010101101101001001001001abcdabcd000000000000000111111111111111100100100序號途徑對應(yīng)序列漢明間隔幸存否？1aaaa000 000 0005否2abca111 001 0113是3aaab000 000 1116否4abcb11

15、1 001 1004是5aabc000 111 0017否6abdc111 110 0101是7aabd000 111 1106否8abdd111 110 1014是序號途徑原幸存途徑的間隔新增途徑段新增間隔總間隔幸存否？1abca+a3aa25否2abdc+a1ca23是3abca+b3ab14否4abdc+b1cb12是5abcb+c4bc37否6abdd+c4dc15是7abcb+d4bd04是8abdd+d4dd26否abcd011010010101001abcd111100100110110110011010010101101001001abcdabcd000 11110010000

16、0 011011001101110011010010101101001001abcdabcd000 111100100000 011011001110011010010101101001001abcdabcd000 111100100000 011011001101和在低信噪比條件下得到接近理想的性能。和在低信噪比條件下得到接近理想的性能。內(nèi)編碼器(n, k)調(diào)制器信道解制器內(nèi)解碼器(n, k)外解碼器(N, K)外編碼器(N, K)輸入輸出RSCC交錯器RSCCbibic1ic2iDDbibicia11a12a1ma21a22a2man1an2anmxxx1234xxx1234x x x 1 xxx1xxx x x x