信道编码和差错控制ppt课件

1、混合信道混合信道 停止等待ARQ系统接收数据ACKACKNAKACKACKNAKACK1233455t发送数据12334556t有错码组有错码组拉后ARQ系统214365798接收数据有错码组有错码组910 1110 11 12576ACK1NAK5NAK9ACK55769521436798发送数据10 1110 11 12重发码组重发码组选择重发ARQ系统9接收数据有错码组有错码组214365759810 11131412发送数据9958521436710 1113 1412重发码组重发码组NAK9ACK1NAK5ACK5ACK9000 111 就能检测两个以下错码，或纠正一个错码。就能检测

2、两个以下错码，或纠正一个错码。k个信息位r个监督位an-1an-2.arar-1an-2.a0t码长 n = k + r分组码的结构(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汉明距离ed0码距等于3的两个码组120 tdBtA汉明距离012345td0码距等于5的两个码组AB1tt汉明距离e码距等于(e+t+1)的两个码组)(10teted10-610-510-410-310-210-1编码后Eb/n0 (dB)编码和误码率关系PeCDEAB2PSK10-610-510-410-310-21

3、0-1编码后Eb/n0 (dB)编码和误码率关系PeCDEAB2PSKBsssbRnPTnPnTPnE0000)/1 (10-610-510-410-310-210-1编码后Eb/n0 (dB)编码和误码率关系PeCDEAB2PSK)(/00dBnEnEGcbubdB0021aaann1021aaannjnjnjppCnjP)1 (),()!( !jnjnCnj2/1222)1 (njjnjnjuppCP2/ )1(1222)1 (njjnjnjuppCP2/1222)1 (njjnjnjuppCP82443242204442242212424210666126)1 (6)1 ()1 ()1

4、(ppppppppppCppCppCPjjjjunmnmnk)1()1(0021aaann021aaaSnn021aaaSnn021aaaSnn1212rknrr或1212rknrr或24561aaaaS13562aaaaS03463aaaaS000034613562456aaaaaaaaaaaa346035614562aaaaaaaaaaaa24561aaaaS13562aaaaS03463aaaaS10 ed120 td1212rrrnk000034613562456aaaaaaaaaaaa010011010010101100010111012345601234560123456aaaaa

5、aaaaaaaaaaaaaaaa010011010010101100010111012345601234560123456aaaaaaaaaaaaaaaaaaaaa0001011001110101011101000123456aaaaaaa101100111010101110100HrPIH0011011010110110011103456012101111011110aaaaaaa346035614562aaaaaaaaaaaaQ34563456012011101110111aaaaaaaaaaa0110001101001011001001111000QGkI IG34560123456aa

6、aaaaaaaaaA0121aaaaAnn0121bbbbBnnB A = E (模2)0121eeeeEnniiiiiababe当当, 1, 0的距离即对应位不同的数目必定是另一个码组的距离即对应位不同的数目必定是另一个码组(A1 + A2)的重量即的重量即“1的数目）。因此，码的最小距离就是的数目）。因此，码的最小距离就是码的最小重量除全码的最小重量除全“0码组外）。码组外）。向右移一位即得到第向右移一位即得到第7码组。码组。012211)(axaxaxaxTnnnn11010011)(25623456xxxxxxxxxxTnpnpQnm,)()()()(xRxQxNxF）（模)()()(

7、xNxRxF）（模) 1(133xx）（模) 1(113224xxxxx结论：一个长为结论：一个长为n的循环码必定为按模的循环码必定为按模(xn + 1)运算的一个余式。运算的一个余式。）（模) 1()()(nixxTxTx012211)(axaxaxaxTnnnn)()(1102211011112211xTaxaxaxaxaxaxaxaxaxaxTxininininniniinininninni1)(256xxxxT）（模) 1()(723535893xxxxxxxxxxTxG34560123456aaaaaaaaaaaA0110001101001011001001111000QGkI I)

8、()()()()(21xgxxgxgxxgxxkkG)()()()(2xgxxgxgxxG001011101011101011100)(xG)()()()()()()()()()(452645262456456xgaxaxaxgaxxgaxgxaxgxxgxgxaaaxaaaxTG）（模) 1()()(nixxTxTx1)()(1)(nnkxxTxQxxTx)() 1()(xTxxTxnk)() 1()(xTxxTxnk)()(1xhxxgxkn) 1)(1)(1(13237xxxxxx1) 1)(1(2423xxxxxx1) 1)(1(2343xxxxxx)()()()()(xgxrxQxg

9、xmxkn11) 1(1)()(24222456xxxxxxxxxxxxgxmxkn10111101111101111100000)(/)()()(/)(xgxrxQxgxR)(/ )()()(/ )(xgxrxQxgxR2PSK汉明码(7, 4) t=1 汉明码(31, 26) t=1扩展戈莱码(24, 12) t=3BCH码(127, 64) t=10Eb / n0 (dB)Pe编码输出每次输入k比特1k1k1k1k 1 k2k3kNk 12nNk级移存器n个模2加法器每输入k比特旋转1周123b3b1输入b2编码输出c2c1c3321331211bbbcbbcbc000111001110

10、011100010101000111001110011100010101c1c2c3000100111011001101110010c1c2c3111000001110c1c2c3信息位 1 1 0 1ba起点信息位000111c1c2c3abcdabcdabcdabcd上半部下半部10a形状 b3b2 a 0 0 b 0 1 c 1 0 d 1 1abcdabcdcdab011001321331211bbbcbbcbc123b3b1输入b2编码输出c2c1c3abcd000111101110010011100001110110110110011011011010010010101101101

11、001001001001abcdabcd000000000000000111111111111111100100100abcd000111101110010011100001abcdabcd110010001111100110110110110011011011010010010101101101001001001001abcdabcd000000000000000111111111111111100100100abcd011010010101001abcd111100100110110110011010010101101001001abcdabcd000 111100100000 01101

12、1001101110011010010101101001001abcdabcd000 111100100000 011011001110011010010101101001001abcdabcd000 111100100000 011011001101和在低信噪比条件下得到接近理想的性能。和在低信噪比条件下得到接近理想的性能。内编码器(n, k)调制器信道解制器内解码器(n, k)外解码器(N, K)外编码器(N, K)输入输出RSCC交织器RSCCbibic1ic2iDDbibicia11a12a1ma21a22a2man1an2anmxxx1234xxx1234x x x 1 xxx1xxx x x x (a) 第14比特输入时的状态xx2567834x5678x x 2 5 x2x51xx x x x (b) 第58比