Carrier?frequency?和?EARFCN的關(guān)系

我們處理UE?log時(shí)，看到LTE?cell?都是用EARFCN/PCI來(lái)標(biāo)示的，那么EARFCN和frequency?之間是什么關(guān)系呢？

1.?EARFCN:????

縮寫(xiě):??????????E-UTRA?Absolute?Radio?Frequency?Channel?Number,?

取值范圍:?0?–?65535

?參考3GPP?36.101?Table?5.7.3-1?E-UTRA?channel?numbers

下圖中的

? ??NDL:??Downlink?EARFCN

?????FDL_low:??The?lowest?frequency?of?the?downlink?operating?band

?????NOffs-DL:??Offset?used?for?calculating?downlink?EARFCN

?

?????NUL:??Uplink?EARFCN.

?????FUL_low:??The?lowest?frequency?of?the?uplink?operating?band

?????NOffs-UL:??Offset?used?for?calculating?uplink?EARFCN

?

?

我們先理解DL?EARFCN,?首先關(guān)注列[Range?of?NDL],??每個(gè)band?對(duì)應(yīng)一個(gè)EARFCN范圍，仔細(xì)觀察，會(huì)發(fā)現(xiàn)EARFCN的數(shù)值會(huì)隨著band增加(eg,?band1->band2->band3…..)而增加，且不同band?對(duì)應(yīng)的EARFCN范圍不存在重合(overlapping)的問(wèn)題。也就是說(shuō)一個(gè)EARFCN對(duì)應(yīng)一個(gè)band.

接下來(lái)關(guān)注列[FDL_low],?FDL_low的意思對(duì)應(yīng)的band?的frequency?的最小值，單位MHz,?每個(gè)band?對(duì)應(yīng)的frequency?的范圍可以參考3GPP?36.101?Table?5.5-1,?如下：

?

仔細(xì)觀察，你會(huì)發(fā)現(xiàn)frequency?與?band?的關(guān)系好亂，沒(méi)有一個(gè)線性關(guān)系(不像EARFCN),且不同band?間的frequency?范圍存在overlapping，比如band?38?–?[2570~2620]?與?band?41?–?[2496~2690],??band?38?對(duì)應(yīng)的frequency?是?band?41的子集。這種現(xiàn)象叫做MFBI,?不過(guò)這里不做經(jīng)一部擴(kuò)展，以后會(huì)做詳細(xì)介紹。一個(gè)frequency?可能對(duì)應(yīng)多個(gè)band.

接下來(lái)，我們來(lái)看frequency?和?EARFCN的計(jì)算公式，可以參考3GPP?36.101?–?5.7.3

?

FDL：?Downlink??Frequency?

NDL:??Downlink?EARFCN

FDL_low:??The?lowest?frequency?of?the?downlink?operating?band?????

? ? ??//Band?對(duì)應(yīng)的最小值，eg,?Band38,?這個(gè)值就是2570MHz

?NOffs-DL:??Offset?used?for?calculating?downlink?EARFCN

??????????????//band?對(duì)應(yīng)Earfcn范圍的起始值，?eg,?Band?38,?這個(gè)值就是37750

?

下面來(lái)計(jì)算band?38?中EARFCN為38000對(duì)應(yīng)的frequency

?

FDL???=???FDL_low??+?0.1?(NDL?-?NOffs-DL)

? ? ? ? ? ? =?2570?+?0.1?(38000?–?37750)

? ? ? ? ? ? =?2595 MHz

?

下面來(lái)計(jì)算band?41?中EARFCN為40640對(duì)應(yīng)的frequency

FDL???=???FDL_low??+?0.1?(NDL?-?NOffs-DL)

???????=??2496??+?0.1?(40640?-?39650)

???????=??2595 MHz

可見(jiàn)EARFCN?38000?(band?38)?和?40640?(band?41)?對(duì)應(yīng)的frequency?都是2595 MHz.

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