LTE system information block introduction (SystemInformationBlockType1)

SystemInformationBlockType1 has basic serving cell information and scheduling of other System Information. This concept should be separated from SIB2 and other SIBs.

(1) cellSelectionInfo
IE q-RxLevMin. This value is used to determine lowest RSRP value to consider serving cell as valid cell.

q-RxLevMin * 2 = Qrxlevmin in 36.304

The cell selection criterion S is fulfilled when:

Srxlev > 0 AND Squal > 0

where 

Srxlev = Qrxlevmeas - (Qrxlevmin - Qrxlevminoffset) - Pcompensation

Squal = Qqualmeas - (Qqualmin - Qqualminoffset)

Pcompensation = max(PEMAX - PPOWERCLASS, 0)

PEMAX is maximum TX power at UE

PPOWERCLASS is maximum RF output power of UE according to UE power class defined in 36.101

Qrxlevmeas and Qqualmeas is measured power in RSRP and RSRQ respectively. 

Qrxlevminoffset and Qqualminoffset are not applicable for initial cell search. 

Qqualmin = IE q-QualMin, if not present, default value negative infinity shall be applied. 36.331 6.2.2

PEMAX = IE p-Max, if not present, maximum power according to UE capability shall be used. 

PPOWERCLASS is 23dBm if not specifically defined. 

Following is an example of defining a valid serving cell in terms of cell selection criteria. 

If q-RxLevMin = -70 and no other IEs are present in SystemInformationBlockType1. Qrxlevmeas = -130dBm. Qqualmeas is -6dB

Srxlev = -130dBm - (-140dBm - 0) - 0 = 10dBm > 0

Squal = -6dB - (- infinity - 0) = positive infinity > 0

This cell would be considered as valid cell. Also, from above equation, it is clear that once parameter q-QualMin is not present, only RSRP value is considered for cell evaluation. 

(2) plmn-IdentityList

IE plmn-Identity has structure of PLMN list with MCC (Mobile Country Code) and MNC (Mobile Network Code). MCC has 3 digits and MNC has 2 digits.

(3) cellReservedForOperatorUse
Is this cell reserved for operator. Used in case someone accidentally shut down live cell.

(4) trackingAreaCode 
16-bits string. Shared for all PLMNs listed in the same bracket. Usually converted back to decimal.

(5) cellIdentity
28-bits string. Starting from left, first 20-bits is eNBId and rest 8-bits is cell PCI.

(6) cellBarred
Indicate if cell is barred or not.

(7) intraFreqReselection
Used to control cell reselection to intra-frequency cells when the highest ranked cell is barred, or treated as barred by the UE, as specified in TS 36.304

(8) csg-Indication
If set to TRUE the UE is only allowed to access the cell if it is a CSG member cell, if selected during manual CSG selection or to obtain limited service, see TS 36.304

(9) freqBandIndicator
Indicate the current frequency band

(10) si-Periodicity
Periodicity of the SI-message in radio frames, such that rf8 denotes 8 radio frames, rf16 denotes 16 radio frames, and so on.

(11) si-WindowLength
Common SI scheduling window for all SIs. Unit in milliseconds, where ms1 denotes 1 millisecond, ms2 denotes 2 milliseconds and so on.

(12) systemInfoValueTag
Common for all SIBs other than MIB, SIB1, SIB10, SIB11, SIB12 and SIB14. Change of MIB and SIB1 is detected by acquisition of the corresponding message.