What is the purpose of deltaTib in 36.101 for inter-band CA?

For carrier aggregation the UE is allowed to set its configured maximum output power P_CMAX,c  on serving cell c and its total configured maximum output power P_CMAX.

The configured maximum output power on serving cell c shall be set within the following bounds: P_{CMAX_L,c} ≤  P_CMAX,c  ≤  P_{CMAX_H,c}

 For inter-band carrier aggregation:

–           P_{CMAX_L,c} = MIN { P_EMAX,c – T_C,c,  P_PowerClass – MAX(MPR _c + A-MPR _c + T_IB,c, P-MPR _c) – T_C, c }

–           P_{CMAX_H,c} = MIN {P_EMAX,c, P_PowerClass}

–           P_EMAX, c is the value given by IE P-Max for serving cell c.

–           P_PowerClass is the maximum UE power.

–           T_IB,c is the additional tolerance for serving cell c.

For inter-band carrier aggregateion, MPR _c and A-MPR _c apply per serving cell c. For intra-band contiguous carrier aggregation, MPR _c = MPR and A-MPR _c = A-MPR with MPR and A-MPR.

–           P-MPR _c accounts for power management for serving cell c. For intra-band contiguous carrier aggregation, there is one power management term for the UE, P-MPR, and P-MPR _c = P-MPR.

–           T_C,c = 1.5 dB or 0 dB.

 For inter-band carrier aggregation with one UL serving cell the total configured maximum output power P_CMAX shall be set within the following bounds: P_{CMAX_L} ≤  P_CMAX  ≤  P_{CMAX_H}

Where:

–           P_{CMAX_L}   = P_{CMAX_L,c}

–           P_{CMAX_H}   = P_{CMAX_H,c}

For intra-band contiguous carrier aggregation, Pcmax,c is calculated under the assumption that the transmit power is increased by the same amount in dB on all component carriers.

For inter-band carrier aggregation, Pcmax,c is calculated under the assumption that the transmit power is increased independently on all component carriers.

The measured maximum output power P_UMAX shall be within the following bounds: P_{CMAX_L}  –  T(P_{CMAX_L})  ≤  P_UMAX  ≤  P_{CMAX_H}  +  T(P_{CMAX_H})

 –           T(P_CMAX) applies to P_{CMAX_L} and P_{CMAX_H} separately.

 For carrier aggregation with two UL serving cells, the total configured maximum output power P_CMAX shall be set within the following bounds: P_{CMAX_L_CA} ≤  P_CMAX  ≤  P_{CMAX_H_CA}

For intra-band contiguous carrier aggregation,

–           P_{CMAX_L _CA} = MIN{10 log₁₀ ∑ p_EMAX,c  – T_C , P_PowerClass – MAX(MPR + A-MPR, P-MPR ) – T_C}

–           P_{CMAX_H_CA}  = MIN{10 log₁₀ ∑ p_EMAX,c , P_PowerClass}

where

–           p_EMAX,c is the linear value of P_EMAX, c which is given by IE P-Max for serving cell c.

–           P_PowerClass is the maximum UE power.

–           MPR and A-MPR specified above.

–           P-MPR is the power management term for the UE.

–           T_C is the highest value T_C,c among all serving cells c in the subframe over both timeslots. T_C,c = 1.5 dB or 0 dB (does not apply to the serving cell c)

For inter-band carrier aggregation with up to one serving cell c per operating band:

P_{CMAX_L_CA}  = MIN {10log₁₀∑ MIN [ p_EMAX,c/ (t_C,c),  p_PowerClass/(mpr_c·a-mpr_c·t_C,c ·t_IB,c) , p_PowerClass/(pmpr_c·t_C,c) ], P_PowerClass}

P_{CMAX_H_CA}  = MIN{10 log₁₀ ∑ p_EMAX,c , P_PowerClass}

where

–           p_EMAX,c is the linear value of P_EMAX, c which is given by IE P-Max for serving cell c.

–           P_PowerClass is the maximum UE power. p_PowerClass is the linear value of P_PowerClass.

–           MPR _c and A-MPR _c apply per serving cell c. mpr _c is the linear value of MPR _c. a-mpr _c is the linear value of A-MPR _c.

–           P-MPR _c accounts for power management for serving cell c. pmpr_c is the linear value of P-MPR _c.

–           t_C,c = 1.41 (not in all cases).

–           t_C,c = 1 (not in all cases).

–           t_IB,c  is the linear value of the inter-band relaxation term of the serving cell c T_IB,c. t_IB,cwhen no inter-band relaxation is allowed.

The measured maximum output power P_UMAX over all serving cells shall be within the following range:

P_{CMAX_L_CA}  –  T(P_{CMAX_L_CA})  ≤  P_UMAX  ≤  P_{CMAX_H_CA}  +  T(P_{CMAX_H_CA})

P_UMAX = 10 log₁₀ ∑ p_UMAX,c 

where p_UMAX,c  denotes the measured maximum output power for serving cell c expressed in linear scale.

The tolerance T(P_CMAX) applies to P_{CMAX_L_CA} and P_{CMAX_H_CA} separately.

For the UE which supports inter-band carrier aggregation configurations with uplink assigned to one E-UTRA band the ΔT_IB,c is defined for applicable bands:

• Inter-band CA Configuration = CA_1A-5A -> For E-UTRA Band= 1 or 5 the value of ΔT_IB,c  [dB] is 0.3.
  
• Inter-band CA Configuration = CA_1A-19A -> For E-UTRA Band= 1 or 19 the value of ΔT_IB,c  [dB] is 0.3.
  

 The ΔT_IB,c above have been derived for a UE supporting a single interband LTE CA band combination. For a UE supporting additional interband LTE CA band combinations, the ΔT_IB,c for all bands supported by the UE, need to be studied.