【正文】 圖44一個(gè)下行時(shí)隙又分為若干個(gè)OFDM符號(hào)，根據(jù)CP的長度不同，包含的OFDM符號(hào)的數(shù)量也不同。一個(gè)下行時(shí)隙包含6個(gè)OFDM符號(hào)。時(shí)隙內(nèi)結(jié)構(gòu)也基本和下行相同，唯一的不同在于一個(gè)時(shí)隙包含7個(gè)（對(duì)于常規(guī)CP）或6個(gè)（對(duì)于擴(kuò)展CP）DFTSOFDM塊（Block）（通常也可以稱為DFTSOFDM符號(hào)），而非OFDM符號(hào)。簡單的說，時(shí)分就是不同的用戶占用不同的時(shí)間，而頻分是不同的用戶占用不同的頻率。在TDD方式的移動(dòng)通信系統(tǒng)中，接收和發(fā)送使用同一頻率載波的不同時(shí)隙作為信道的承載，其單方向的資源在時(shí)間上是不連續(xù)的，時(shí)間資源在兩個(gè)方向上進(jìn)行了分配。如圖46: 圖46 FDDLTE工作原理頻分雙工(FDD)和時(shí)分雙工(TDD)是兩種不同的雙工方式。因此，F(xiàn)DD必須采用成對(duì)的頻率，依靠頻率來區(qū)分上下行鏈路，其單方向的資源在時(shí)間上是連續(xù)的。如圖47： 圖47 FDD與TDD相比優(yōu)缺點(diǎn)。而TDD則不需要成對(duì)的頻率，通信網(wǎng)絡(luò)可根據(jù)實(shí)際情況靈活地變換信道上下行的切換點(diǎn)，能有效地提高系統(tǒng)傳輸不對(duì)稱業(yè)務(wù)時(shí)的頻譜利用率。這是因?yàn)?，目前TDD系統(tǒng)在芯片處理速度和算法上還達(dá)不到更高的標(biāo)準(zhǔn)。而收、發(fā)采用一定頻段間隔的FDD系統(tǒng)則難以采用。，使用FDD可消除鄰近蜂窩區(qū)基站和本區(qū)基站之間的干擾，F(xiàn)DD系統(tǒng)的抗干擾性能在一定程度上好于TDD系統(tǒng)。 圖51 圖52 圖53 ECCMU裝配過程檢查MDA_GE的開關(guān)是是否在OFF狀態(tài)和螺絲是否已經(jīng)擰好,將散熱膠裝在氣管前端,確認(rèn)點(diǎn)膠機(jī)的設(shè)置正確,將散熱膠依次涂在MDA_GE的大芯片上。 圖54如散熱膠涂太少，則裝上散熱片后，散熱膠和散熱片接觸不到，這種情況下需拆除散熱片后，增加膠涂的量，如圖55。并確認(rèn)彈簧螺釘已膨脹開，如圖56。 MIBOTS測試MIBOTS測試平臺(tái)有三部分組成：PC和Windows XP組成的控制單元，測量儀器儀表組成的機(jī)架，圖57和測試維修夾具，圖58。第一， LTE有利于加快科技自主創(chuàng)新。第二， LTE有利于推動(dòng)經(jīng)濟(jì)結(jié)構(gòu)調(diào)整。第三， LTE有利于提升國家信息安全。第四， LTE有利于構(gòu)建新型信息社會(huì)。當(dāng)前，要構(gòu)建新型的信息社會(huì)以及實(shí)現(xiàn)大國和平崛起，優(yōu)先發(fā)展新一代信息技術(shù)是關(guān)鍵。第一，國家應(yīng)該加快明確LTE的發(fā)展方針并且制定LTE的發(fā)展規(guī)劃。第二，國家要積極改善各個(gè)地區(qū)對(duì)LTE的發(fā)展前景。中國應(yīng)該有更多像華為那樣具有國際影響力的企業(yè)。2008年6月，3GPP完成了LTEA的技術(shù)需求報(bào)告，提出了LTEA的最小需求：下行峰值速率1Gbit/s，上行峰值速率500Mbit/s，上下行峰值頻譜利用率分別達(dá)到15Mbit/s/Hz和30Mbit/s/Hz。Aggregation，CA）、多點(diǎn)協(xié)作傳輸（CoordinatedTxamp。UL/DL LTE發(fā)展建議全球LTE的進(jìn)展無論是在標(biāo)準(zhǔn)制定還是產(chǎn)業(yè)發(fā)展都走向了快車道，其中TDLTE是我國特別關(guān)注的。但同時(shí)也必須看到，TDLTE與FDD因此，必須下大力氣進(jìn)一步推進(jìn)TDLTE在各方面盡快成熟。FDD應(yīng)盡早明確TDLTE的使用頻率。應(yīng)關(guān)注多網(wǎng)協(xié)調(diào)發(fā)展。TDLTE網(wǎng)絡(luò)建設(shè)運(yùn)營后，需要與其它移動(dòng)網(wǎng)絡(luò)一起準(zhǔn)確定位，協(xié)調(diào)發(fā)展，這樣才能保證LTE有效率、有效益的可持續(xù)發(fā)展。經(jīng)驗(yàn)表明，終端是移動(dòng)通信網(wǎng)絡(luò)運(yùn)營發(fā)展的關(guān)鍵因素，也是發(fā)展過程中的薄弱環(huán)節(jié)。Term當(dāng)前全球移動(dòng)通信產(chǎn)業(yè)對(duì)LTE寄予厚望，期待這一技術(shù)能夠增強(qiáng)移動(dòng)通信產(chǎn)業(yè)持續(xù)發(fā)展能力。英國沃達(dá)豐、日本NTT DoCoMo、美國ATamp。Wireless等世界主要電信運(yùn)營商已經(jīng)決定采用LTE技術(shù)，中國移動(dòng)作為全球最大的移動(dòng)通信運(yùn)營商也宣布加入LTE在全球眾多移動(dòng)運(yùn)營商、設(shè)備制造商的普遍支持下，LTE展現(xiàn)了美好的未來。TDLTE可以提供更高的帶寬，通過更加靈活的頻譜配置方案（～20MHz） 來提升網(wǎng)絡(luò)效率和單個(gè)基站效率，還可以通過弱化基站控制器設(shè)備實(shí)體、采用公共無線資源管理控制基站來簡化系統(tǒng)結(jié)構(gòu)，減少網(wǎng)絡(luò)節(jié)點(diǎn)，從而更加有效地提供服務(wù)。LTE是中國縮短同國際通信產(chǎn)業(yè)差距的一個(gè)機(jī)會(huì)，引入LTE要求運(yùn)營商從語音服務(wù)轉(zhuǎn)向以信息服務(wù)為主，豐富的個(gè)人通信需求將推動(dòng)LTE技術(shù)的引進(jìn)開發(fā)和4G網(wǎng)絡(luò)建設(shè)的啟動(dòng)，而新技術(shù)、新網(wǎng)絡(luò)的發(fā)展將為通信網(wǎng)絡(luò)建設(shè)技術(shù)服務(wù)提供商提供更多的業(yè)務(wù)機(jī)會(huì)。在四年的學(xué)習(xí)生活中，老師嚴(yán)謹(jǐn)?shù)闹螌W(xué)態(tài)度、認(rèn)真踏實(shí)的工作作風(fēng)、精益求精的精神給我留下了深刻的印象，不時(shí)給我們以鼓勵(lì)和督促。我所做的工作和取得的成績是與嚴(yán)老師的辛勤工作是分不開的，在此特致以衷心的感謝！三年的學(xué)習(xí)中，還得到了很多老師和同學(xué)的幫助，在此不一一的列出，一并致以謝意！最后，衷心感謝我的父母，感謝他們一直以來對(duì)我的培養(yǎng)、關(guān)懷和支持，我前進(jìn)的每一步都飽蘸著他們殷切的期望。 with a limited extent due to small packet sizes and strict delay bounds. However, the high degree of flexibility in dynamic scheduling of users is obtained at thecost of high control signaling overhead. First of all, the BS needs frequencyselective CQI to be reported in Physical Uplink Control Channel (PUCCH) by each UE. However, since PUCCH capacity is limited, only nonfrequencyselective wideband CQI may be feasible, especally for VoIP with high number of active users. Secondly, as the data channel is shared, the BS needs to signal in PDCCH which users are being scheduled every TTI. This signalling information includes the Physical Resource Blocks (PRBs),Modulation and Coding Scheme (MCS) and related Hybrid ARQ (HARQ) information for each UE scheduled in either UL or DL. Also PDCCH capacity is limited restricting the amount of multiplexed users per TTI. For LTE with high VoIP capacity requirements, the PUCCH and PDCCHconsumption/limitations might bee the bottlenecks for VoIP performance. Thus, a semipersistent packet scheduling (SPS) scheme for VoIP has been specified for 3GPP Release 8 to battle against the control channel constraints. VoIP service in 3G LTE has been studied . in [2], [3], [4], [5] and [6]. However, the VoIP capacity has not been studied with realistic PDCCH, despite it clearly has a critical effect of the VoIP performance. Impact of CQI pression and reporting mechanism on VoIP capacity has been studied in [7]. However, realistic PDCCH and semipersistent PS were not taken into account. In [8] the PDCCH and its impact on the packet scheduling performance has been studied. However, the study considers only a full buffer traffic model and the effect on the frequency domain packet scheduling performance. But, the effect of PDCCH restrictions on the multiplexed users per TTI is presumably much higher with VoIP traffic due to small packet sizes and strict delay bounds. The objective of this article is study the VoIPperformance in DL with realistic PDCCH including differentpacket scheduling schemes and CQI reporting resolution. The analysis is performed with fully dynamic system level simulator, thus also mobility and handovers are accurately modelled.II. VOICEOVERIP AND RELATED MODELINGA. VoiceoverIP traffic The characteristics of VoIP traffic can be described as bursty with strict delay requirements. VoIP traffic is considered to be provided by AMR codec with Discontinuous Transmission, Voice Activity Detector and Comfort NoiseGeneration. AMR provides small packets transmitted with a constant rate depending on speech activity: One VoIP packet at 20 ms intervals during active period (talkspurt) and one Silence Description (SID) packet at 160 ms intervals during silent period. Also, in LTE the IP, UDP and RTP headersare pressed with Robust Header Compression (ROHC) to improve the spectral efficiency. This kind of traffic type leads to a fact that the amount of UEs needed to be scheduled might vary drastically per TTI. According to [9], the maximum acceptable mouthtoear delay for voice is on the order of 250 ms。LTE旨在雄心勃勃下行100[ 1 ]。然而，很明顯，LTE的應(yīng)該是至少一樣好高速分組接入（HSPA）也在語音演變的軌跡。LTE是分組數(shù)據(jù)傳輸和核心網(wǎng)絡(luò)的優(yōu)化純粹的分組交換，因此語音與VoIP純粹的傳播協(xié)議。這些事實(shí)的VoIP用戶設(shè)置的挑戰(zhàn)設(shè)備（UE）的資源分配：分組調(diào)度（PS），鏈接適應(yīng)（LA）和物理下行控制信道（PDCCH）。這意味著配置可以改變傳輸時(shí)間間隔（TTI）到另一個(gè)允許在基站中的調(diào)度器（BS）的基礎(chǔ)上進(jìn)行優(yōu)化調(diào)度和鏈路適配的決定例如，信道質(zhì)量指示（CQI）信息。然而，在用戶的動(dòng)態(tài)調(diào)度的靈活性的高度處獲得高控制信令開銷。然而，由于PUCCH的能力是有限的，只有非頻率選擇性寬帶CQI可能是可行的，特別是對(duì)于VoIP活躍用戶的數(shù)量。該信令信息包括物理資源塊（PRBS），的調(diào)制和編碼方案（MCS）和相關(guān)的混合ARQ（HARQ）每個(gè)UE安排在UL或DL信息。為LTE因此，一個(gè)半持續(xù)調(diào)度（SPS）方案，VoIP已經(jīng)3GPP版本8對(duì)控制信道約束指定的戰(zhàn)斗。VoIP服務(wù)進(jìn)行了研究，例如在[ 2 ]，[ 3 ]，[ 4 ]，[ 5 ]和[ 6 ]。影響CQI壓縮和報(bào)告對(duì)VoIP容量的機(jī)理進(jìn)行了研究在[ 7 ]。PS未納入帳戶。然而，研究認(rèn)為，只有充分緩沖區(qū)的交通模型和頻域分組的影響調(diào)度性能。本文的目的是研究帶有現(xiàn)