【課件】GSM-R(GSM-Railway)__第7章-無線測量

1、無線測量第7章內(nèi)容提要無線測量的基本原理不連續(xù)傳輸DTX無線測量的處理方法算術(shù)平均加權(quán)平均標(biāo)準(zhǔn)處理與快速處理測量數(shù)據(jù)的丟失處理距離質(zhì)量測量判決: 越區(qū)切換, 功率控制, 呼叫清除處理信號強(qiáng)度一、移動(dòng)通信中對無線測量的要求判決過程與參數(shù)處理優(yōu)先級二、無線測量的流程 無線測量的結(jié)果是判決越區(qū)切換和功率控制的準(zhǔn)則。移動(dòng)臺測量下行鏈路的信號強(qiáng)度和信號質(zhì)量，基站測量上行鏈路的信號強(qiáng)度和信號質(zhì)量。 移動(dòng)臺在測量報(bào)告中包含的測量數(shù)據(jù)： 下行鏈路接收的信號電平：RXLEV_DL 下行鏈路接收的信號質(zhì)量，即誤比特率（BER）：RXQUAL_DL 下行鏈路相鄰小區(qū)的信號電平：RXLEV_NCELL(n) Laye

2、r 1 Header消息中傳輸?shù)臏y量數(shù)據(jù)： 移動(dòng)臺與基站的距離 移動(dòng)臺當(dāng)前使用的功率：MS_TXPWR和MS_TXPWR_CONF 基站計(jì)算的測量數(shù)據(jù) 上行鏈路接收的信號電平：RXLEV_UL 上行鏈路接收的信號質(zhì)量：RXQUAL_UL 基站當(dāng)前使用的功率：BS_TXPWR 無線測量過程描述無線測量的報(bào)告消息Mobile MeasurementsDecision of Mobile Power ControlCall Clearing IndicationHandover IndicationL1M: Layer One ManagementBSCL1MBTSTRAFFICMANAGEMENT

3、D0D1D2D3D4D5D6D7A0A1A2A3-D0D1D2D3D4D5D6D7A4A5A6A7-A5A6A7D0D1D2D3D4D5D6D7A0-A1A2A3D0D1D2D3D4D5D6D7A4-SDCCH/8(downlink)SDCCH/8(uplink) 235 msOn SDCCH1 SACCH message block consists of 4 SACCH TS.A complete measurement report is sent every 2 x 235 = 470 ms.Di: data conveyed on sub-channel iAi: SACCH blo

4、ck associated with block Di三、無線測量的報(bào)告周期TCHTCHTCHTCHSACCHIdleOn TCH120 ms1 SACCH message block consists of 4 SACCH TS.A complete measurement report is sent every 4 x 120 = 480 ms.12 TCH12 TCH.無線測量報(bào)告周期無線測量數(shù)據(jù)處理方法的三要素(對象、算法、時(shí)間): 需要對功率電平、通信質(zhì)量、鄰小區(qū)評估、距離進(jìn)行平均處理； 兩種平均算法：算術(shù)平均(標(biāo)準(zhǔn))和加權(quán)平均； 規(guī)定每一次平均運(yùn)算的周期。無線測量的三要素RXLE

5、VRXLEV:Received signal level averaged over a complete SACCH block period and coded onto 6 bits (0-63)RXLEV in dBm = -110 + RXLEV= RXLEV ranges between -110 and -47 dBm四、無線測量的數(shù)據(jù)類型1、RXLEV(信號電平)RXQUAL表示的是一個(gè)測量報(bào)告周期內(nèi)接收的信號質(zhì)量的平均值，長度為3比特，范圍從0到7 。 2、無線通信質(zhì)量的測量 RXQUAL與誤比特率的對應(yīng)關(guān)系RXQUAL誤比特率平均值0 12.8%18.10%誤比特率與RXQ

6、UAL（i）的換算公式為：平均誤比特率 = 2 1/2 2i 0.1% TS13 TSTiming Advance d = 2 x tTDMA Frame FThe compensation of the propagation delay is by the advancing MS transmission time of d.The BTS continuously measures time offset between the burst schedule and the received burst.TS1TS1TS1Without TATS expected by the BTS

7、3 TS - dTS2OverlappingTS2TS2TS2Anticipation of the MS transmissiont3、無線傳播時(shí)延和定時(shí)提前量的測試處于專用模式The BTS permanently evaluates Timing Advance TA for Frame Alignment.TA: 0 . 63The BTS permanently evaluates MS_BS Distance used as a criterion for HO and Call Clearing.MS_BS DISTANCE (m) = TA_TO_M * Timing adva

8、nce TATA_TO_M = T*v / (2 * BP)with: T = Duration of one timeslot (secs)= 3/5200 577 sBP = No. of bit periods in one timeslot = 156.25v = velocity of light MS_BS DISTANCE range = 0 - 63定時(shí)提前量和MS-BS距離數(shù)據(jù)的描述方法MS_TXPWR and MS_TXPWR_CONF are expressed as a power control level from the maximum TXPWR possibl

9、e in the band:The Power Control Levels are not converted into dBm for the storageBS_TXPWR and BS_TXPWR_CONF are expressed as a power control levelin the range 0-15 (not in dBm), from the maximum TXPWR allowed for the BTS through bsTxPwrMax parameter.功率控制電平Power Control LevelNominal Output Power (900

10、 MHz)0 43 . 41 dBm1 41 . 39 dBm2 39 . 37 dBm. . . . . .空閑空閑TC25TC24復(fù)幀 i復(fù)幀 i+1臨近BTSTS0TS0 監(jiān)視窗口TS0TS0TS0 在鄰近小區(qū)的BCCH頻率上測量TC1處于當(dāng)前小區(qū)的移動(dòng)臺TC25TC24TC1五、對鄰小區(qū)的監(jiān)視和測量下行鏈路上行鏈路減少干擾延長手機(jī)電池工作時(shí)間aabb小區(qū) b小區(qū) a六、不連續(xù)傳輸采用DTX 不采用DTX 下行鏈路測量報(bào)告RXLEV_SUB_SERVING_CELLRXQUAL_SUB_SERVING_CELLRXLEV_FULL_SERVING_CELLRXQUAL_FULL_SERV

11、ING_CELL上行鏈路測量報(bào)告RXLEV_SUB_UPRXQUAL_SUB_UPRXLEV_FULL_UPRXQUAL_FULL_UPBTS測量RxLevUL_SUBRxLevUL_FULLRxQualUL_SUBRxQualUL_FULLBTS設(shè)置DTX標(biāo)志DTX_USED或DTX_NOT USEDMS測量RxLevDL_SUBRxLevDL_FULLRxQualDL_SUBRxQualDL_FULLMS設(shè)置DTX標(biāo)志DTX_USED或DTX_NOT USED不連續(xù)傳輸對無線測量的影響七、標(biāo)準(zhǔn)平均算術(shù)平均 算術(shù)平均是對最新的XXHreqave個(gè)數(shù)據(jù)(L1M收到的測量結(jié)果中的數(shù)據(jù))進(jìn)行計(jì)算，

12、并在收到每個(gè)新的測量報(bào)告時(shí)就計(jì)算一次，即使目前并不需要這些值，也需要計(jì)算。加權(quán)平均 加權(quán)平均是對XXHreqt個(gè)數(shù)據(jù)(測量值或算術(shù)平均值)進(jìn)行計(jì)算，并且只有當(dāng)需要的時(shí)候才會計(jì)算一次，即只有當(dāng)距離、質(zhì)量或電平的平均值需要與判決門限進(jìn)行比較時(shí)才會計(jì)算它們的加權(quán)平均值。每當(dāng)runCallClear、runPwrControl或runHandOver出現(xiàn)時(shí)，才會計(jì)算加權(quán)平均。 算術(shù)平均和加權(quán)平均相結(jié)合八、短平均(快速處理)TIME權(quán)重舉例:XXHreqave = 4XXHreqt = 3Weights = 45, 30, 25253045PAST12 SACCH塊 6 sPRESENTTIMET0HR

13、EQAVE x HREQTWEIGHTING IS A WAY OF GIVING MORE IMPORTANCE TOPRESENT OVER PAST MEASUREMENTS 標(biāo)準(zhǔn)處理PRESENTPASTNo handover decision before Hreqave*Hreqt Level and Quality measurements and rxNCellHreqave neighboring cells measurements.標(biāo)準(zhǔn)處理不能滿足特定的需要HOW?Arithmetic averaging on less measurementsSHORTER AVERA

14、GESWHY?To enable a quicker handover decision (HO on PBGT only)WHAT?Level on the current + neighboring cellsWHO?Fast moving MSslow reselection process MS turning at a street cornerMS entering a tunnelSHORTER AVERAGES ARE USED IN THE EARLY HANDOVER DECISION PROCESSDCU4 and DRX architectures only當(dāng)前小區(qū)的短

15、平均相鄰小區(qū)的短平均 九、測量數(shù)據(jù)丟失處理 丟失下行鏈路測量空中接口問題短消息業(yè)務(wù)丟失SACCH塊由四個(gè)準(zhǔn)則，可以彌補(bǔ)丟失數(shù)據(jù)對測量的影響。準(zhǔn)則1-3用于服務(wù)小區(qū)的電平、質(zhì)量和距離；準(zhǔn)則4用于相鄰小區(qū)的接收電平。對丟失數(shù)據(jù)處理的必要性準(zhǔn)則1 準(zhǔn)則1規(guī)定，電平、質(zhì)量和距離丟失的測量報(bào)告由最近的平均值加權(quán)上O&M的因子missXXWt代替：丟失的測量報(bào)告 = 最近的平均值missXXWt其中，missRxQualWt的范圍為100%200%，默認(rèn)值為110%；missRxLevWt的范圍為0%100%，默認(rèn)值為90%；missDistWt的范圍為100%200%，默認(rèn)值為110%。 準(zhǔn)則2 準(zhǔn)則2

16、規(guī)定，如果沒有電平、質(zhì)量和距離的平均值，則丟失的測量報(bào)告由最近的測量報(bào)告加權(quán)上O&M的因子missXXWt代替：丟失的測量報(bào)告 = 最近的測量報(bào)告missXXWt準(zhǔn)則3 準(zhǔn)則3規(guī)定，如果丟失的測量報(bào)告位于測量過程的初始階段（即之前沒有測量值），則用默認(rèn)值代替丟失的測量報(bào)告。 丟失的測量報(bào)告 電平； = 默認(rèn)值 = 32 (-78 dBm) 質(zhì)量； = 3 距離 ； = 由基站控制器在測量初始階段向基站提供的默認(rèn)距離準(zhǔn)則4 準(zhǔn)則4規(guī)定，對于相鄰小區(qū)，根據(jù)移動(dòng)臺報(bào)告的新小區(qū)電平的不同，有兩類代替丟失的測量數(shù)據(jù)： 類型a：如果相鄰小區(qū)的最低接收電平比丟失測量數(shù)據(jù)的小區(qū)的最新測量強(qiáng)，則丟失的數(shù)據(jù)由最新

17、接收的數(shù)值代替。 類型b：如果相鄰小區(qū)的最低接收電平比丟失測量數(shù)據(jù)的小區(qū)的最新測量弱，則丟失的數(shù)據(jù)由最低接收電平與missOffset（默認(rèn)值為3dB）的差值代替。 x C2x C3x C1 x C1R1 R2x C2x C1 x C3 x C1R1 R2- missOffsetNew reported cellMissing measurementIf Mini (Ci (R2) (= C3 ) C1 (R1)ThenC1 (R2) = C1 (R1)If Mini (Ci (R2) (= C3 ) C1 (R1)ThenC1 (R2) = C3 (R2) - missOffset (3 d

18、B)準(zhǔn)則4Case a Case brxQualHreqave = 4r = Measurement report m = mean?= missing measurement report= received measurement reportr1 = quality default_value = 3r3 = r2 * missRxQualWt r8 = m1 * missRxQualWtm1m2averagingaveraging?r1r2r3r4r5r6r7r8time?r4 = r3 * missRxQualWtMissing Downlink MeasurementsExample of missing measurement handling: Case of downlink RXQUAL 測試題1、無線測量過程主要集中在_完成。A、移動(dòng)臺(MS) B、基站(BTS)2、無線測量用于判決越區(qū)切換、功率控制和呼叫清除，這三者的處理優(yōu)先級(從高到低)為_。A、呼叫清除-越區(qū)切換-功率控制 B、越區(qū)切換-