Section: 6.1.3.6b Dual Connectivity Power Headroom Report MAC Control Element
Content: The Dual Connectivity Power Headroom Report (PHR) MAC control element is identified by a MAC PDU subheader with LCID as specified in table 6.2.1-2. It has a variable size and is defined in Figure 6.1.3.6b-1 and Figure 6.1.3.6b-2. One octet with Ci fields is used for indicating the presence of PH per serving cell other than PCell, when the highest SCellIndex of SCell with configured uplink is less than 8, otherwise four octets are used. In case EN-DC, NE-DC or NGEN-DC is configured, four octets with Ci fields is always used. When Type 2 PH is reported for the PCell, the octet containing the Type 2 PH field is included first after the octet(s) indicating the presence of PH per cell (PSCell and all SCells of all MAC entities) and followed by an octet containing the associated PCMAX,c field (if reported). Then after that, when Type 2 PH is reported for the PSCell, the octet containing the Type 2 PH field is included followed by an octet containing the associated PCMAX,c field (if reported). Then follows an octet with the Type 1 PH field and an octet with the associated PCMAX,c field (if reported), for the PCell. If SRS-ConfigAdd-r16 is configured for the PCell then follows an octet with the Type 3 PH field and an octet with the associated PCMAX,c field (if reported), for the PCell. And then follows in ascending order based on the ServCellIndex, as specified in TS 36.331[ Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification ]  [8], an octet with the Type x PH field, wherein x is either 1 or 3 according to TS 36.213[ Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures ]  [2] and TS 38.213[ NR; Physical layer procedures for control ]  [18] and an octet with the associated PCMAX,c field (if reported), for all serving cells of all MAC entities indicated in the bitmap. In case of EN-DC and NGEN-DC, for serving cells in the other MAC entity in which the UE does not support dynamic power sharing or dynamic power sharing is not applicable (clause 4.2.7.9, TS 38.306[ NR; User Equipment (UE) radio access capabilities ]  [22]), the UE may omit the octets containing Power Headroom field and PCMAX,c field for those serving cells. In case of NE-DC, for serving cells in the other MAC entity in which the UE does not support dynamic power sharing or dynamic power sharing is not applicable, the UE may omit the octets containing Power Headroom field and PCMAX,f,c field for those serving cells except for the PCell in the other MAC entity and the reported values of Power Headroom and PCMAX,f,c for the PCell are up to UE implementation. The Dual Connectivity PHR MAC Control Element is defined as follows: - Ci: this field indicates the presence of a PH field for the serving cell of any MAC entity, except the PCell, with ServCellIndex (for EN-DC, NE-DC or NGEN-DC case) or SCellIndex i as specified in TS 36.331[ Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification ]  [8]. The Ci field set to "1" indicates that a PH field for the serving cell with ServCellIndex (for EN-DC, NE-DC or NGEN-DC case) or SCellIndex i is reported. The Ci field set to "0" indicates that a PH field for the serving cell with ServCellIndex (for EN-DC, NE-DC or NGEN-DC case) or SCellIndex i is not reported; - R: reserved bit, set to "0"; - V: this field indicates if the PH value is based on a real transmission or a reference format. For Type 1 PH, V=0 indicates real transmission on PUSCH and V=1 indicates that a PUSCH reference format is used. For Type 2 PH, V=0 indicates real transmission on PUCCH and V=1 indicates that a PUCCH reference format is used. For Type 3 PH, V=0 indicates real transmission on SRS and V=1 indicates that an SRS reference format is used. Furthermore, for Type 1 ,Type 2 and Type 3 PH, V=0 indicates the presence of the octet containing the associated PCMAX,c field, and V=1 indicates that the octet containing the associated PCMAX,c field is omitted. Whether the reported PH value for an activated NR Serving Cell is based on real transmission or a reference format is determined based on UL transmissions that have been scheduled or configured until 4 ms prior to the TTI in which this PHR MAC CE is transmitted; - Power Headroom (PH): this field indicates the power headroom level. The length of the field is 6 bits. The reported PH and the corresponding power headroom levels are shown in Table 6.1.3.6-1 (the corresponding measured values in dB for the E-UTRA Serving Cell are specified in clause 9.1.8.4 of TS 36.133[ Evolved Universal Terrestrial Radio Access (E-UTRA); Requirements for support of radio resource management ]  [9] while the corresponding measured values in dB for the NR Serving Cell are specified in TS 38.133[ NR; Requirements for support of radio resource management ]  [19]); - P: this field indicates whether power backoff due to power management is applied (as allowed by P-MPRc, see TS 36.101[ Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio transmission and reception ]  [10] and TS 38.101[ None ] -3 [21]). The MAC entity shall set P=1 if the corresponding PCMAX,c field would have had a different value if no power backoff due to power management had been applied; - PCMAX,c: if present, this field indicates the PCMAX,c or , as specified in TS 36.213[ Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures ]  [2] for the E-UTRA Serving Cell and the PCMAX,f,c or P̃CMAX,f,c, as specified in TS 38.213[ NR; Physical layer procedures for control ]  [18]) for the NR Serving Cell used for calculation of the preceding PH field. The reported PCMAX,c and the corresponding nominal UE transmit power levels are shown in Table .6a-1 (the corresponding measured values in dBm for the E-UTRA Serving Cell can be found in TS 36.133[ Evolved Universal Terrestrial Radio Access (E-UTRA); Requirements for support of radio resource management ]  [9] while the corresponding measured values in dBm for the NR Serving Cell can be found in TS 38.133[ NR; Requirements for support of radio resource management ]  [19]). Figure 6.1.3.6b-1: Dual Connectivity PHR MAC Control Element Figure 6.1.3.6b-2: Dual Connectivity PHR MAC Control Element supporting 32 serving cells with configured uplink