無線參數(shù)-lte prach配置分析

引 編寫目 文檔組 參考資 PRACH信道的配置分 PRACH信道的配置參 PRACH配置索引（prach- 零相關(guān)配置 根序列索引 是否為高速狀態(tài) 頻率偏移（prach- PRACH信道參數(shù)的配置步 鄰小區(qū)的PRACH信道的配 LTE典型PRACH配 密度為1情況下PRACH相關(guān)參數(shù)配 密度為2情況下PRACH相關(guān)參數(shù)配 附 規(guī)模實驗址分布 引LTE3.0PRACH信道的各參數(shù)進(jìn)行了說明和描述，根據(jù)網(wǎng)本文檔的預(yù)期讀者為LTE網(wǎng)絡(luò)建設(shè)和LTE網(wǎng)絡(luò)優(yōu)化、測試等《LTE無線配置參數(shù)分析.doc3GPPTS36.211PhysicalChannelsandCubic RandomAccessRandomAccessPRACH信道的配置分PRACH無無prach-->無PRACHPRACH的頻域資源索引、時域的無同時也確定了采用的前導(dǎo)格式（0~470~3，47~574，其定義見下表（36.211Table5.7.1-4。 UL/DLconfiguration(SeeTable4.2-0123456(SeeTable5.7.1-012345678920/21/22/23/24/25/26/27/28/29表格中(fRA,t(0),t(1),t(2))RARAfRAprach-FrequencyOffsetPRACH信道的頻t(0)0,1,2PRACH信道的無線幀位置，0為全部無線幀，1為奇數(shù)無線幀，2為tt

t(2PRACH信道在“5ms半幀”內(nèi)的上子幀序號，帶*表示在UpPTS小區(qū)邊緣隨機接入信號是由CP（長度為TCP）、前導(dǎo)序列（長度為TSEQ）和GT(長度為TGT)三個部Preamble格式和小區(qū)覆蓋范圍的關(guān)系約束原則為：小區(qū)內(nèi)邊緣用戶的傳輸時延需要在 TCPTRTTTDS，TGT其中，TTCPCPTGTTRTT根據(jù)以上關(guān)系，可以得到各種格式下所支持小區(qū)的最大半徑(考慮TDS)CP長度(TssGTTDS(s012345Preamble0：持續(xù)1ms，序列長度800us，適用于小、中型的小區(qū)，最大小區(qū)半徑Preamble12ms800us，適用于大型的小區(qū)，最大小區(qū)半徑為Preamble格式2：持續(xù)2ms，序列長度1600us，適用于中型小區(qū)，最大小區(qū)半徑為Preamble33ms，1600us，適用于超大型小區(qū)，最大小區(qū)半徑為Preamble式4：DD模的式持時間15.292μ（2個OFD符號的發(fā).4km，RACHPRACH定在某時間間隔TN（用戶數(shù)足夠大，即用戶間），隨機接入的資源數(shù)為Tm（隨機接入的資源數(shù)由PRACH的密度m表示每10ms內(nèi)的preambles碼數(shù)preambles），用戶等概率地選擇這些資源中的一個，任一用戶A的碰撞概率為pUE。A（共Tm個資源）Tm1N它用戶都選擇其他Tm1個資源，其概率約為

Tm

。即用戶A TNpUE=1%（LTE中，檢測到碰撞后就均用于競爭隨機接入

m

，則一個PRACH資源可以接入的用戶數(shù)N64ln10.010.6432個。如果一個無線幀（10ms）PRACH資源（即密度為2則每秒鐘可以接入的用戶數(shù)為N100264ln1pUE128這就是3GPP相關(guān)提案中給出的不同RACH負(fù)載下的碰撞概率曲線，其中第二幅圖是對第一幅圖在碰撞概率低于1%時的縮放。途中橫坐標(biāo)表示1sRACH的總次數(shù)（競爭式，縱坐標(biāo)表示碰撞概率，64signatures表示10ms64preamble可用，128signatures128preamble可用。從第一幅圖可以看出如果目標(biāo)碰撞概率設(shè)為低于1%，則每10ms128個preamble200次/s的競爭式隨機接入。163264128loadCallestablishment Handover Handover 刻上被保留，而下行資源分配（下行數(shù)據(jù)到達(dá)）只是需要在1個隨機接入時刻上1個1.9（8.8+58.3）5

access/second，或者period平均需要分配3.37個1P0–P1-…Px0.5%x=9，9preable上述7000個UE時的非競爭式的隨機接入負(fù)載以看出非競爭式隨機接入的preamblePRACH3500PRACH密度配置為PRACH4UpPTS時Format0PRACH。PRACHonfgraondexRACHPRACH的時域配置不同：onfigurationIndex（prach-FrequencyOffsetPRACHreqecyfet無無無2）2:32.1.4節(jié)的“是否為高速狀態(tài)（highSpeedFlag”指示。3

forpreamblegeneration(preambleformats0-UnrestrictedUnrestrictedRestricted00123456789-

forpreamblegeneration(preambleformat

02142638456789Ncs與小區(qū)半徑的NCSNNZCTsNCSNNZCTsrTRTTc 0-3N245764N4096；0-3NZC8394NZC139；TDSUE對抗多徑干擾的保護(hù)；c為光速。4，Ncs數(shù)值及其對應(yīng)的最大小區(qū)半徑(假設(shè)TDS5.21us)關(guān)系表。表 前導(dǎo)格式0~3時Ncs值與支持的最大小區(qū)半0011.021.331.742.352.863.774.585.797.51012.416.1233959--徑02142638456徑02142638456K=

（其中,K0-3NZC8394NZC13964646。表 Ncs值和產(chǎn)生64個前導(dǎo)需要的根序列NCS配NCS0014252637384956810Format4021（eoCorelationZoeCofig0..837（format40~137）無無無環(huán)移位產(chǎn)生的，小區(qū)使用的根序列的起始根序列的邏輯序號由本參數(shù)進(jìn)行配置，參見表45u所支持的最大的Ncs_max進(jìn)行了分組，使得同一組內(nèi)的Ncs滿足NCS（g）≤率的程度，CM越低，對射頻硬件要求比較低)排序，位置連續(xù)的根序列CM值始終CM838CM組和高CM0~455CM值的根序列優(yōu)先使用。LogicalrootsequencenumberPhysicalrootsequencenumber(inincreasingorderofthecorrespondinglogicalsequence129,710,140,699,120,719,210,629,168,671,84,755,105,734,93,746,70,769,60,2,837,1,56,783,112,727,148,80,759,42,797,40,35,804,73,766,146,31,808,28,811,30,809,27,812,29,24,815,48,791,68,771,74,765,178,661,136,86,753,78,761,43,796,39,800,20,819,21,95,744,202,637,190,649,181,658,137,702,125,714,151,217,622,128,711,142,697,122,717,203,636,118,721,110,729,89,750,103,736,778,55,784,15,824,14,12,827,23,816,34,805,37,802,46,793,207,632,179,660,145,694,130,709,223,228,611,227,612,132,707,133,706,143,696,135,704,161,678,201,638,173,666,733,83,756,91,748,66,773,53,786,10,829,9,7,832,8,831,16,823,47,792,64,775,57,782,104,735,101,738,108,731,208,631,655,197,642,191,648,121,718,141,698,149,690,216,623,218,152,687,144,695,134,705,138,701,199,640,162,677,176,663,119,720,158,681,675,174,665,171,668,170,669,87,752,169,670,88,751,107,732,81,758,82,757,739,98,741,71,768,59,780,65,774,50,789,49,790,26,813,17,822,13,826,6,5,834,33,806,51,788,75,764,99,740,96,743,97,742,166,673,172,667,175,664,652,163,676,185,654,200,639,114,725,189,650,115,724,194,645,195,644,192,182,657,157,682,156,683,211,628,154,685,123,716,139,700,212,627,153,686,626,215,624,150,225,614,224,615,221,618,220,619,127,712,147,692,124,715,193,646,205,634,633,116,723,160,679,186,653,167,672,79,760,85,754,77,762,92,747,58,781,777,69,770,54,785,36,803,32,807,25,814,18,821,11,828,4,3,836,19,820,22,817,41,798,38,801,44,795,52,787,45,794,63,776,67,772,767,76,763,94,745,102,737,90,749,109,730,165,674,111,728,209,630,204,635,722,188,651,159,680,198,641,113,726,183,656,180,659,177,662,196,643,155,214,625,126,713,131,708,219,620,222,617,226,230,609,232,607,262,577,252,587,418,421,416,423,413,426,411,428,376,463,444,283,556,285,554,379,460,390,449,363,476,384,455,388,451,386,453,361,387,452,360,479,310,529,354,485,328,511,315,524,337,502,349,490,335,504,323,516,320,519,334,505,359,480,295,544,385,454,292,547,291,548,381,458,440,380,459,397,442,369,470,377,462,410,429,407,432,281,558,414,425,247,277,562,271,568,272,567,264,575,259,237,602,239,600,244,595,243,596,275,564,278,561,250,589,246,593,417,422,591,394,445,393,446,370,469,365,474,300,539,299,540,364,475,362,477,298,312,527,313,526,314,525,353,486,352,487,343,496,327,512,350,489,326,513,520,332,507,333,506,348,491,347,492,322,330,509,338,501,341,498,340,499,342,497,301,538,366,473,401,438,371,468,431,375,464,249,590,269,570,238,601,234,257,582,273,566,255,584,254,585,245,594,251,588,412,427,372,467,282,557,436,396,443,392,447,391,448,382,457,389,450,294,545,297,542,311,528,344,345,494,318,521,331,508,325,514,321,346,493,339,500,351,488,306,533,289,550,400,439,378,461,374,465,415,424,569,241,231,608,260,579,268,571,276,563,409,430,398,441,290,549,304,535,308,531,481,316,293,546,288,551,284,555,368,471,253,586,256,583,263,242,597,274,565,402,437,383,456,357,482,329,317,522,307,532,286,553,287,552,266,573,261,236,603,303,536,356,355,484,405,434,404,435,406,235,604,267,572,302,309,530,265,574,233,367,472,296,336,503,305,534,373,466,280,559,279,560,419,420,240,599,258,581,229,Table5.7.2-5:RootZadoff-ChusequenceorderforpreambleformatPhysicalrootsequencenumber(inincreasingorderofthecorrespondinglogicalsequence06920–40–60–80–100–120--138–0~455之間的根序列。為避免相鄰小區(qū)之間的干擾，建議相鄰小區(qū)之間的根序列配置和使用都不相同，即64個前導(dǎo)碼的情況下，其相鄰小區(qū)應(yīng)避開其他小區(qū)使用的根無無高速標(biāo)對于高速移動環(huán)境下的UE，由于效應(yīng)，會破壞ZC序列不同循環(huán)移位之間的正TRUENCS選擇限制集。TRUE無無prach-無PRACH信道的頻域位置。LTEPUCCHPRACHPUCCH2/2a/2b的可用資源塊/2+PUCCH1/1a/1b的可用資源塊/2+”MSG3單邊預(yù)留資源長度”<=PRACH

NUL-

PUCCH2/2a/2b塊

+PUCCH1/1a/1b的可用資源塊

)-

PRACH/

MSG3源長度，其NUL為上行系統(tǒng)帶寬PRB數(shù)UP->MAC配置參數(shù)->MSG3單邊預(yù)留資源長度PRB調(diào)度的復(fù)雜度，目前建議配置相同。PRACH確定時頻位置，最終確定“PRACHhighSeedFlag（higSpeedFlag”來確Ncs的大小。選擇根序列。注：高速低速情況下，需要根據(jù)Ncs選擇根序列。低速情況下根序列配置NcsNcs可以對應(yīng)不同的根序列；Ncs64N，即為本小區(qū)需要占用的根5N-1個根序列都屬于本小區(qū)使用的根序列。LTE典型PRACH配Cell-Cell-Cell-Cell- Cell-Cell-Cell-Cell-Cell- Cell-Cell-Cell- Cell-Cell-Cell-Cell-Cell-Cell-Cell- Cell-Cell-Cell-3Format0PRACH針對圖3中的蜂窩網(wǎng)絡(luò)分針對RACH密度12情況下小區(qū)進(jìn)行了PRACH相關(guān)參數(shù)的建議配置，參見表11、表12。各小區(qū)按照半徑為1km考慮，PRACH選擇Format0格式，零相關(guān)配置為1即Ncs=13，一個根序列可以生成64個前導(dǎo)碼，故小區(qū)之間配置根序列時，1PRACH11Format01PRACH小區(qū)mod小區(qū)色PRACH置索高速狀Cell-0紅310Cell-1綠411Cell-2藍(lán)512Cell-0紅313Cell-1綠414Cell-2藍(lán)515Cell-0紅316Cell-1綠417Cell-2藍(lán)518Cell-0紅319Cell-1綠41Cell-2藍(lán)51紅綠藍(lán)紅綠藍(lán)紅Cell-1綠41Cell-2藍(lán)514PRACHformat01RACH 置PRACH配置PRACH配置11Format01PRACH小區(qū)mod小區(qū)色PRACH置索高速狀Cell-0紅610Cell-1綠711Cell-2藍(lán)612Cell-0紅613Cell-1綠714Cell-2藍(lán)615Cell-0紅616Cell-1綠717Cell-2藍(lán)618Cell-0紅619Cell-1綠71Cell-2藍(lán)61紅綠藍(lán)紅綠藍(lán)紅Cell-1綠71Cell-2藍(lán)61=offset2offset1-620M，offset2100-offset1-65PRACHformat02RACHPRACH配置PRACH配置PRACH配置62PRACHFormat4PRACH3Format4PRACH13.PRACHFormat4RACH0.5Uppts1，2PRACHPRACH13Format40.5PRACH小區(qū)mod圖示PRACH置索高速狀Cell-0紅60Cell-1綠62Cell-2藍(lán)64Cell-0紅66Cell-1綠68Cell-2藍(lán)6Cell-0紅6Cell-1綠6Cell-2藍(lán)6Cell-0紅6Cell-1綠6Cell-2藍(lán)6Cell-0紅6Cell-1綠6Cell-2藍(lán)6Cell-0紅6Cell-1綠6Cell-2藍(lán)6Cell-0紅6Cell-1綠6Cell-2藍(lán)6高速模式下配置原2.2.1PRACHNCS，然后根據(jù)下表（10）查找對應(yīng)的邏輯根參數(shù),Ncs15，則在≥24的邏輯根序列選擇即可；若Ncs18,則根序列需要在≥30的邏輯根序列選擇配置。

Physicalrootsequencenumber(inincreasingorderofthecorrespondinglogicalsequencenumber)

129,710,140,699,120,719,210,629,168,671,84,105,734,93,746,70,769,60,779,2,837,1,56,783,112,727,148,80,759,42,797,40,35,804,73,766,146,31,808,28,811,30,809,27,812,29,24,815,48,791,68,771,74,765,178,661,136,86,753,78,761,43,796,39,800,20,819,21,95,744,202,637,190,649,181,658,137,702,125,151,217,622,128,711,142,697,122,717,203,636,118,110,729,89,750,103,736,61,778,55,784,15,14,12,827,23,816,34,805,37,802,46,793,207,632,660,145,694,130,709,223,228,611,227,612,132,707,133,706,143,696,135,161,678,201,638,173,666,106,733,83,756,748,66,773,53,786,10,829,9,7,832,8,831,16,823,47,792,64,775,57,782,104,101,738,108,731,208,631,184,655,197,642,648,121,718,141,698,149,690,216,623,218,152,687,144,695,134,705,138,701,199,640,162,176,663,119,720,158,681,164,675,174,665,668,170,669,87,752,169,670,88,751,107,732,758,82,757,100,739,98,741,71,768,59,780,774,50,789,49,790,26,813,17,822,13,826,6,5,834,33,806,51,788,75,764,99,740,96,743,97,166,673,172,667,175,664,187,652,163,676,654,200,639,114,725,189,650,115,724,194,195,644,192,647,182,657,157,682,156,683,628,154,685,123,716,139,700,212,627,153,213,626,215,624,150,225,614,224,615,221,618,220,619,127,712,147,124,715,193,646,205,634,206,633,116,723,679,186,653,167,672,79,760,85,754,77,762,747,58,781,62,777,69,770,54,785,36,803,807,25,814,18,821,11,828,4,3,836,19,820,22,817,41,798,38,801,44,795,52,45,794,63,776,67,772,72,767,76,763,94,102,737,90,749,109,730,165,674,111,728,630,204,635,117,722,188,651,159,680,198,113,726,183,656,180,659,177,662,196,643,684,214,625,126,713,131,708,219,620,222,226,230,609,232,607,262,577,252,587,418,421,416,413,426,411,428,376,463,395,444,283,556,554,379,460,390,449,363,476,384,455,388,386,453,361,478,387,452,360,479,310,529,485,328,511,315,524,337,502,349,490,335,324,323,516,320,519,334,505,359,480,295,544,385,292,547,291,548,381,458,399,440,380,459,442,369,470,377,462,410,429,407,432,281,414,425,247