【正文】 111100110000110011110011000011001111001100001115 011010011001011001101001100101100110100110010110011010011001011016 000000000000000011111111111111110000000000000000111111111111111117 010101010101010110101010101010100101010101010101101010101010101018 001100110011001111001100110011000011001100110011110011001100110019 011001100110011010011001100110010110011001100110100110011001100120 000011110000111111110000111100000000111100001111111100001111000021 010110100101101010100101101001010101101001011010101001011010010122 001111000011110011000011110000110011110000111100110000111100001123 011010010110100110010110100101100110100101101001100101101001011024 000000001111111111111111000000000000000011111111111111110000000025 010101011010101010101010010101010101010110101010101010100101010126 001100111100110011001100001100110011001111001100110011000011001127 011001101001100110011001011001100110011010011001100110010110011028 000011111111000011110000000011110000111111110000111100000000111129 010110101010010110100101010110100101101010100101101001010101101030 001111001100001111000011001111000011110011000011110000110011110031 011010011001011010010110011010010110100110010110100101100110100132 000000000000000000000000000000001111111111111111111111111111111133 010101010101010101010101010101011010101010101010101010101010101034 001100110011001100110011001100111100110011001100110011001100110035 011001100110011001100110011001101001100110011001100110011001100136 000011110000111100001111000011111111000011110000111100001111000037 010110100101101001011010010110101010010110100101101001011010010138 001111000011110000111100001111001100001111000011110000111100001139 011010010110100101101001011010011001011010010110100101101001011040 000000001111111100000000111111111111111100000000111111110000000041 010101011010101001010101101010101010101001010101101010100101010142 001100111100110000110011110011001100110000110011110011000011001143 011001101001100101100110100110011001100101100110100110010110011044 000011111111000000001111111100001111000000001111111100000000111145 010110101010010101011010101001011010010101011010101001010101101046 001111001100001100111100110000111100001100111100110000110011110047 011010011001011001101001100101101001011001101001100101100110100148 000000000000000011111111111111111111111111111111000000000000000049 010101010101010110101010101010101010101010101010010101010101010150 001100110011001111001100110011001100110011001100001100110011001151 011001100110011010011001100110011001100110011001011001100110011052 000011110000111111110000111100001111000011110000000011110000111153 010110100101101010100101101001011010010110100101010110100101101054 001111000011110011000011110000111100001111000011001111000011110055 011010010110100110010110100101101001011010010110011010010110100156 000000001111111111111111000000001111111100000000000000001111111157 010101011010101010101010010101011010101001010101010101011010101058 001100111100110011001100001100111100110000110011001100111100110059 011001101001100110011001011001101001100101100110011001101001100160 000011111111000011110000000011111111000000001111000011111111000061 010110101010010110100101010110101010010101011010010110101010010162 001111001100001111000011001111001100001100111100001111001100001163 01101001100101101001011001101001100101100110100101101001100101102023/3/2 星期二擴(kuò)頻 /解擴(kuò)頻? Walsh功能 :? 每個(gè)符號(hào)都需要用 Walsh碼進(jìn)行擴(kuò)頻 .? 在前向 , 用于區(qū)分出不同的用戶(hù) .? 在前 /反向 , 用于區(qū)分信道類(lèi)型 .? 變長(zhǎng) Walsh碼 :對(duì)于不同的信息速率 ,使用不同的長(zhǎng)度的 Walsh碼 ,以確保最后的擴(kuò)頻碼片速率為.64481632129600 19200 38400 76800 153600 307200 614400W01=0W08=00000000W48=00001111W02=00W12=00W04=0000W04=0011W04=0000W04=0011W38=00110011W78=00111100W28=00110011W68=00111100W18=00110011W58=00111100W016 W816W416 W1216W216 W1416W616 W1416W116 W916W516 W1316W316 W1116W716 W1516kbpsWalsh碼階數(shù)2023/3/2 星期二調(diào)制 /解調(diào)l 將低頻的模擬基帶信號(hào)搬移到適于信道傳輸?shù)母哳l段去發(fā)送 .這種頻譜搬移過(guò)程就稱(chēng)為 調(diào)制 ,經(jīng)調(diào)制后的信號(hào)稱(chēng)為已調(diào)信號(hào) .已調(diào)信號(hào)通過(guò)信道傳輸?shù)浇邮斩撕?,則需要將收到的已調(diào)信號(hào)再搬移到低頻的原始基帶頻譜上 ,以恢復(fù)原始信號(hào) ,這一搬移過(guò)程稱(chēng)為 解調(diào) . l 調(diào)制 /解調(diào)分類(lèi) :u 最簡(jiǎn)單的調(diào)制 /解調(diào)技術(shù)是從 2ASK,2FSK,2PSK基礎(chǔ)上發(fā)展起來(lái)的 .u 在 2ASK基礎(chǔ)上 ,產(chǎn)生了正交幅度調(diào)制 QAM,又稱(chēng)星座調(diào)制 .u 在 2FSK向多進(jìn)制調(diào)制技術(shù)上發(fā)展 ,產(chǎn)生了 MFSK.u 在 2PSK在多進(jìn)制的方向上發(fā)展 ,產(chǎn)生了 QPSK,OQPSK, DPSK等 .l 調(diào)制 /解調(diào)技術(shù)在 CDMA中的應(yīng)用 :u 在 CDMA中采用的各項(xiàng)調(diào)制技術(shù)包括 BPSK,QPSK,OQPSK,MPSK等 .u 前向信道中 ,主要采用 QPSK調(diào)制技術(shù) .u 反向信道中 ,采用 OQPSK/HPSK等調(diào)制技術(shù) .2023/3/2 星期二調(diào)制 /解調(diào)l 前向鏈路 : 在前向 ,BTS采用 QPSK調(diào)制 ,并轉(zhuǎn)換為模擬信號(hào) ,混合之后經(jīng)過(guò)射頻發(fā)射 .l 反向鏈路 : 在反向 ,移動(dòng)臺(tái)采用 OQPSK調(diào)制 ,并轉(zhuǎn)換為模擬信號(hào) ,混合之后經(jīng)過(guò)射頻發(fā)射 .2023/3/2 星期二短碼? 短碼 （ Pseudo Noise） :是周期 215 的 M序列 ,速率為 .? 短碼功能 : 系統(tǒng)利用 PN短碼的時(shí)間偏置來(lái)區(qū)別（BTS）扇區(qū) .? 可允許所有 Walsh碼在各（ BTS）扇區(qū)復(fù)用 .? 系統(tǒng)規(guī)定 PN碼最小偏移值為 64chips，共有 512個(gè)時(shí)間偏置（ 215 /64=512） .? 同一（ BTS）扇區(qū)內(nèi)所有 CDMA信道的短碼相同 ,不同（ BTS）扇區(qū)內(nèi)的 CDMA信道的短碼時(shí)間偏置不同 .Cell 1PN 0_120PN1_240 PN2_3602023/3/2 星期二本章小節(jié)l 參照數(shù)據(jù)通信模型 ,請(qǐng)描述 CDMA系統(tǒng)中 ,數(shù)據(jù)處理的基本過(guò)程 .l 信源編碼的作用和類(lèi)型 .l 交織和加擾主要起什么作用 ?l 擴(kuò)頻 /解擴(kuò)頻的過(guò)程和實(shí)現(xiàn)方法 .l 調(diào)制的作用和方法有哪些 ?l 長(zhǎng)碼、短碼和 Walsh碼的作用是什么？2023/3/2