小區(qū)支持大量終端接入

1、2013 Nokia Solutions and Networks. All rights reserved.配置小區(qū)支持大量配置小區(qū)支持大量LTE終端終端Ren Feng2014/1/2422013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use前言前言福州市諾基亞通信設(shè)備區(qū)域已開(kāi)通超過(guò)1000個(gè)LTE站點(diǎn)，需要檢查和修改對(duì)應(yīng)的參數(shù)

2、，保證重點(diǎn)用戶(hù)和大規(guī)模試商用后大量用戶(hù)的使用32013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal useUE容量支持相關(guān)參數(shù)容量支持相關(guān)參數(shù)調(diào)整對(duì)UE容量的支持涉及到的主要是上、下行控制信道部分的參數(shù)，即下行PDCCH相關(guān)，以及上行PUCCH、Prach 相關(guān)部分的參數(shù)。PUCCH需要考慮的主要是CQI資源、SR資源、PUCCH占用PR

3、B數(shù)等。Prach需要考慮的是prach configuration index，以及prach frequency offset等。PDCCH需要考慮的是symbol的數(shù)量，下行每TTI調(diào)度的用戶(hù)數(shù)。42013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use52013 Nokia Solutions and Networks. Al

4、l rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行資源參數(shù)優(yōu)化LTE中，UE需反饋的信道狀態(tài)信息 CSI (Channel state information)分別有CQI、RI和PMI。這些信息反饋的主要目的，是提供eNB下行信道估計(jì)，以便于更好的調(diào)度資源。上行資源最關(guān)鍵的是PUCCH的資源配置，決定PUCCH資源需求的因素主要是2方面：CQI資源和SR(scheduling R

5、equest)資源。其次上行資源還需要關(guān)心接入信道prach的配置。62013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行資源參數(shù)優(yōu)化 CQICQI的上報(bào)，分為周期性上報(bào)和非周期性上報(bào)2類(lèi)，兩種上報(bào)方式都要打開(kāi)，實(shí)現(xiàn)互補(bǔ)：可以配置用戶(hù)在被調(diào)度時(shí)非周期上報(bào)CQI，而周期性上報(bào)可以提供固定周期的，但相對(duì)粗糙一些的信

6、道狀態(tài)。周期性上報(bào)時(shí)，如果UE正好有UL的數(shù)據(jù)發(fā)送，則CQI會(huì)在PUSCH里傳，否則會(huì)占用PUCCH資源。周期性上報(bào)，對(duì)應(yīng)設(shè)置的參數(shù)為 ：cqiPerNp = 20 ( 20ms)periodicCqiFeedbackType = wideband要打開(kāi)非周期上報(bào)，需設(shè)置對(duì)應(yīng)的參數(shù)：CQIAperEnable = truecqiAperMode = FBT272013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NP

7、O Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行資源參數(shù)優(yōu)化 CQICQI資源和其支持的用戶(hù)數(shù)的算法是：支持的用戶(hù)數(shù)= nCqiRb * UL subframe number * cqiPerNp/10 * CQI per PRBnCqiRb 指為CQI分配的RB數(shù)。UL subframe number 目前上下行是1:3，所以每幀有2個(gè)上行子幀。cqiPerNp 如前文所示，設(shè)置為20msCQI per PRB，每個(gè)PRB有6個(gè)CQI資源，注意，打開(kāi)注意，打開(kāi)drx后，此資源減半后，此資源減半，所以為3。82013 Nokia Solut

8、ions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行資源參數(shù)優(yōu)化 CQI假設(shè)每個(gè)小區(qū)支持100個(gè)用戶(hù)，則建議調(diào)整的CQI相關(guān)參數(shù)為：nCqiRb =4。cqiPerNp = 40msCQI per PRB ， 不變?yōu)?。按照上面的設(shè)置，代入公式計(jì)算，支持的用戶(hù)數(shù)為96，基本滿(mǎn)足要求。92013 Nokia Solutions and Netw

9、orks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行資源參數(shù)優(yōu)化 SR每個(gè)SR 周期支持的active用戶(hù)數(shù) = ROUNDUP (No. of UL frame per 10ms * cellSrPeriod (ms) /10, 0) * n1PucchAnNo. of UL frame per 10ms 按照現(xiàn)在上下行1:3的配置，還是2CellSrPeriod

10、指小區(qū)SR的周期，默認(rèn)是20ms。 n1PucchAn 指ACK/NACK offset，默認(rèn)是36。SR (Scheduling Request)對(duì)上行資源的要求是：102013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行資源參數(shù)優(yōu)化 SR假設(shè)每個(gè)小區(qū)支持100個(gè)用戶(hù)，則建議的SR相關(guān)參數(shù)為：cellSrPe

11、riod =20ms。n1PucchAn = 36按照上面的設(shè)置，代入公式計(jì)算，支持的用戶(hù)數(shù)為144，滿(mǎn)足要求。112013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行資源參數(shù)優(yōu)化 PUCCH size根據(jù)上述的SR和CQI資源參數(shù)設(shè)置，需要計(jì)算出總計(jì)需要的PUCCH資源MaxPucchResourceSize

12、 = nCqiRb + roundup(rounddown (maxNrSymPdcch * 12 - 4) * dlChBw - roundup (phichRes * (dlChBw / 8) * 12 - 16) / 36) + n1PucchAn - pucchNAnCs * 3 / deltaPucchShift ) * deltaPucchShift / (3*12) + roundup (pucchNAnCs / 8)代入計(jì)算后，PUCCH所需的PRB數(shù)為12。122013 Nokia Solutions and Networks. All rights reserved.7-M

13、ar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行資源參數(shù)優(yōu)化 prachPrach固定占用了6個(gè)RB，72個(gè)子載波，1.08 Mhz。Prach的位置由Prach configuration index Prach Frequency offset兩個(gè)RRC層的參數(shù)確定。132013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ

14、Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行資源參數(shù)優(yōu)化 prach20M帶寬，100個(gè)PRB，按照上面的PUCCH資源需求，需12個(gè)PRB，分別位于20M的兩端各6個(gè)PRB。建議設(shè)置適當(dāng)?shù)腜rach frequency offset，使得Prach的6個(gè)PRB在頻域上緊貼著PUCCH。 PrachFreqOff的設(shè)置原則：roundup(MaxPucchResourceSize/2) if it is located at the lower e

15、dgeulChBw-6-roundup(MaxPucchResourceSize/2 if it is located at the upper edge of the PUSCH area即，按照12個(gè)PUCCH的PRB計(jì)算，offset為6，或者88。142013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行

16、資源參數(shù)優(yōu)化 prach根據(jù)福建客戶(hù)的要求，現(xiàn)網(wǎng)的無(wú)線(xiàn)規(guī)劃里：宏站采用format 0室分采用format 4即宏站的prach位于上行子幀，室分的prach位于特殊子幀的UpPTS。152013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行資源參數(shù)優(yōu)化 prach室分采用format 4，prach在特殊子幀，

17、prach frequency offset可以設(shè)為0prachConfIndex = 51 or 52，根據(jù)各地的要求設(shè)定prachFreqoff = 0宏站采用format 0，需要按照PUCCH所需資源設(shè)置prach frequency offsetprachConfIndex = 3 or 4，根據(jù)各地的要求設(shè)定prachFreqoff = 6 或者 88如果宏站不按照上述原則設(shè)置頻偏，會(huì)有什么問(wèn)題呢？假設(shè)設(shè)置大于6，如設(shè)置為12，那么PUSCH的資源會(huì)分為2段，6個(gè)PRB位于PUCCH和PRACH之間，其他PRB集中在一起。這樣會(huì)影響峰值速率測(cè)試的結(jié)果，也會(huì)影響PUSCH分配的效率。

18、假設(shè)設(shè)置小于6，會(huì)導(dǎo)致Prach和PUCCH重合，參數(shù)無(wú)法下發(fā)。162013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行資源參數(shù)優(yōu)化 prach此外，prach的資源相關(guān)還有一個(gè)參數(shù) raNondedPreamb，它定義了ra preamble的數(shù)量。LTE的接入分為競(jìng)爭(zhēng)性接入和非競(jìng)爭(zhēng)性接入，后者主要用于切換等

19、場(chǎng)合。競(jìng)爭(zhēng)性接入的preamble + 非競(jìng)爭(zhēng)性接入的 preamble = 64 個(gè)。如果設(shè)置raNondedPreamb = 64，則全部ra資源用于競(jìng)爭(zhēng)性接入。CMCC集團(tuán)測(cè)試的不少場(chǎng)景，要求切換是基于競(jìng)爭(zhēng)性的，可以這么設(shè)置。默認(rèn)的設(shè)置為40，即預(yù)留24個(gè)ra資源給非競(jìng)爭(zhēng)性接入(如切換等)使用，由于ra資源在無(wú)線(xiàn)連接完成后會(huì)釋放掉，所以40個(gè)已經(jīng)足以滿(mǎn)足接入使用，建議依照原始設(shè)置。172013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 /

20、 RSO South MS-NPO Radio Stream / Ren FengFor internal use上行資源參數(shù)優(yōu)化上行資源參數(shù)優(yōu)化上行參數(shù)匯總 (部分默認(rèn)的參數(shù)未列出)：nCqiRb =4cqiPerNp = 40mscellSrPeriod =20ms。n1PucchAn = 36室分prachConfIndex = 51 or 52，根據(jù)各地的要求設(shè)定室分prachFreqoff = 0宏站prachConfIndex = 3 or 4，根據(jù)各地的要求設(shè)定宏站prachFreqoff = 6182013 Nokia Solutions and Networks. All r

21、ights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use192013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use下行資源參數(shù)優(yōu)化下行資源參數(shù)優(yōu)化PD

22、CCH承載上、下行的調(diào)度分配信息。一條PDCCH信道在一個(gè)聚合的CCE上發(fā)送，視乎UE的無(wú)線(xiàn)質(zhì)量，聚合分別需要1/2/4/8個(gè)CCE。PDCCH聚合的樹(shù)形結(jié)構(gòu)如下：202013 Nokia Solutions and Networks. All rights reserved.7-Mar-22LTE NPO FZ Experience Sharing / Ver1.0 / RSO South MS-NPO Radio Stream / Ren FengFor internal use下行資源參數(shù)優(yōu)化下行資源參數(shù)優(yōu)化PDCCH可分配的CCE數(shù)和以下因素相關(guān)：分配給PDCCH的符號(hào)數(shù) (1 3，相關(guān)參數(shù) maxNrSymPdcch )PHICH和PCFICH的占用資源數(shù)。按照每用戶(hù)平均占用3 個(gè)CCE（50%加擾）的仿真原則，PDCCH的符號(hào)數(shù)，及其支持的單小區(qū)同時(shí)調(diào)度的用戶(hù)數(shù)量如下：PDCCH的符號(hào)數(shù)CCE數(shù)量支持的調(diào)度用戶(hù)數(shù)(仿真結(jié)果)CFI=1217CFI=25518CFI=38829212013 Nokia Solutions and Networks. All rights reserved.7-