第10章信道編碼與差錯(cuò)控制

1、1信信 源源發(fā)送端發(fā)送端接收端接收端信道編碼信道編碼調(diào)調(diào) 制制信信 道道壓縮編碼壓縮編碼解解 調(diào)調(diào)信信 宿宿保密解碼保密解碼信道解碼信道解碼壓縮解碼壓縮解碼保密編碼保密編碼噪聲噪聲同步同步信信 源源編編 碼碼信信 源源解解 碼碼2345 停止等待ARQ系統(tǒng)接收數(shù)據(jù)ACKACKNAKACKACKNAKACK1233455t發(fā)送數(shù)據(jù)12334556t有錯(cuò)碼組有錯(cuò)碼組拉后ARQ系統(tǒng)214365798接收數(shù)據(jù)有錯(cuò)碼組有錯(cuò)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6選擇重發(fā)ARQ系統(tǒng)9接收數(shù)據(jù)有錯(cuò)碼組

2、有錯(cuò)碼組214365759810 11131412發(fā)送數(shù)據(jù)9958521436710 1113 1412重發(fā)碼組重發(fā)碼組NAK9ACK1NAK5ACK5ACK978信息位監(jiān)督位晴000云011陰101雨110k個(gè)信息位r個(gè)監(jiān)督位an-1an-2.arar-1an-2.a0t碼長(zhǎng) n = k + r分組碼的結(jié)構(gòu)9(0,0,0)(0,0,1)(1,0,1)(1,0,0)(1,1,0)(0,1,0)(0,1,1)(1,1,1)a2a0a11010 ed0123BA漢明距離ed0碼距等于3的兩個(gè)碼組120 tdBtA漢明距離012345td0碼距等于5的兩個(gè)碼組11AB1tt漢明距離e碼距等于(e+t

3、+1)的兩個(gè)碼組)(10teted1210-610-510-410-310-210-1編碼后Eb/n0 (dB)編碼和誤碼率關(guān)系PeCDEAB2PSK1310-610-510-410-310-210-1編碼后Eb/n0 (dB)編碼和誤碼率關(guān)系PeCDEAB2PSK14BsssbRnPTnPnTPnE0000)/1 (10-610-510-410-310-210-1編碼后Eb/n0 (dB)編碼和誤碼率關(guān)系PeCDEAB2PSK15)(/00dBnEnEGcbubdB160021aaann1021aaann1711na12na11a10a21na22na21a20amna1mna2ma1ma0

4、1nc2nc1c0cnmnmnk)1()1(180021aaann021aaaSnn021aaaSnn19021aaaSnn1212rknrr或20S1 S2 S3錯(cuò)碼位置S1 S2 S3錯(cuò)碼位置001a0101a4010a1110a5100a2111a6011a3000無(wú)錯(cuò)碼1212rknrr或24561aaaaS13562aaaaS03463aaaaS21000034613562456aaaaaaaaaaaa346035614562aaaaaaaaaaaa信息位a6 a5 a4 a3監(jiān)督位a2 a1 a0信息位a6 a5 a4 a3監(jiān)督位a2 a1 a0000000010001110001

5、01110011000010101101001000111101011001010011011000010101101110101001100111110100011100011111112224561aaaaS13562aaaaS03463aaaaSS1 S2 S3錯(cuò)碼位置S1 S2 S3錯(cuò)碼位置001a0101a4010a1110a5100a2111a6011a3000無(wú)錯(cuò)碼2310 ed120 td1212rrrnk24000034613562456aaaaaaaaaaaa010011010010101100010111012345601234560123456aaaaaaaaaaaaa

6、aaaaaaaa25010011010010101100010111012345601234560123456aaaaaaaaaaaaaaaaaaaaa0001011001110101011101000123456aaaaaaa26101100111010101110100HrPIH001101101011011001110A = a6 a5 a4 a3 a2 a1 a0 0 = 000273456012101111011110aaaaaaa346035614562aaaaaaaaaaaaQ34563456012011101110111aaaaaaaaaaa280110001101001011

7、001001111000QGkI IG34560123456aaaaaaaaaaaA290121aaaaAnn0121bbbbBnnB A = E (模2)0121eeeeEnniiiiiababe當(dāng)當(dāng), 1, 03031碼組編號(hào)信息位監(jiān)督位碼組編號(hào)信息位監(jiān)督位A6a5a4a3a2a1a0a6a5a4A3a2a1a0100000005100101120010111610111003010111071100101401110018111001032012211)(axaxaxaxTnnnn11010011)(25623456xxxxxxxxxxT33npnpQnm,34)()()()(xRxQx

8、NxF）（模)()()(xNxRxF）（模) 1(133xx）（模) 1(113224xxxxx35）（模) 1()()(nixxTxTx012211)(axaxaxaxTnnnn)()(1102211011112211xTaxaxaxaxaxaxaxaxaxaxTxininininniniinininninni1)(256xxxxT）（模) 1()(723535893xxxxxxxxxxTx36G34560123456aaaaaaaaaaaA0110001101001011001001111000QGkI I3738)()()()()(21xgxxgxgxxgxxkkG碼組編號(hào)信息位監(jiān)督位碼

9、組編號(hào)信息位監(jiān)督位A6a5a4a3a2a1a0a6a5a4A3a2a1a0100000005100101120010111610111003010111071100101401110018111001039)()()()(2xgxxgxgxxG001011101011101011100)(xG)()()()()()()()()()(452645262456456xgaxaxaxgaxxgaxgxaxgxxgxgxaaaxaaaxTG4041nktg(x)nktg(x)172123334191212222122324727166353435145664713347656573245340465244430733571076135430006717177735374243編碼輸出每次輸入k比特1k1k1k