Page 933 - 5G Basics - Core Network Aspects

Transport aspects 2

12.3.3.2.11 O-PRM

The O-PRM message provides the FTU-R parameter update.

Table 12-35 – O-PRM message

Field Field name Format
1 Message descriptor Message code
2 Proposed MEDLEY set of active US subcarriers Band descriptor
3 Final MEDLEY set of active DS subcarriers Band descriptor

4 FTU-R Rx gain update Gain descriptor
5 BLACKOUTus set Tone descriptor
6 US reference PSDMASK (MREFPSDMASKus) PSD descriptor
7 Request for retrain One byte
Field 1 "Message descriptor" is a unique one-byte code (0516) that identifies the message. See Table 12-7
for a complete list of codes.
Field 2 "Proposed MEDLEY set of active US subcarriers" includes a complete set of upstream MEDLEY
subcarriers using the band descriptor presented in Table 12-21, along with all subcarriers from the
BLACKOUTus set (field 5) that fall within the range of frequencies for the included complete set of
upstream MEDLEY subcarriers. This set is proposed to the FTU-R to constrain the upstream MEDLEY set.
Field 3 "Final MEDLEY set of active DS subcarriers" includes a complete set of downstream MEDLEY
subcarriers using the band descriptor presented in Table 12-21, along with all subcarriers from the
BLACKOUTds set (R-SNR message, field 4) that fall within the range of frequencies for the included
complete set of downstream MEDLEY subcarriers. The final MEDLEY set of active DS subcarriers shall
consist of all subcarriers included in this field except the BLACKOUTds subcarriers.
Field 4 "FTU-R Rx gain update" indicates the gain compensation factor per subcarrier to be applied by the
FTU-R to its receiver stage to accommodate the transition from PRMPSDds (used during the PRM-UPDATE
stage) to MREFPSDds (used during Channel Analysis & Exchange phase). The field shall be encoded as gain
descriptor as defined in Table 12-36. The gain descriptor contains the gain compensation factors for a range
of subcarriers in the MEDLEY set. Each subcarrier of the MEDLEYset is referenced by a MEDLEYset index, m,
corresponding to its position in the MEDLEYset, i.e., m=0 is the index of first subcarrier in the MEDLEYset,
m=1 is the index of the second one, etc. The bytes 1 & 2 of the gain descriptor contain the index m of the
first subcarrier of the range and the byte 3 & 4 contain the index m of the last subcarrier of the range. The
following bytes contain the gain compensation factors of subcarriers arranged by ascending index m,
expressed in dB. Each gain compensation factor expressed in dB shall be coded as a 1 byte unsigned
integer, representing valid values -25.4dB to +25.4dB in increments of 0.2 dB (the values 0, 127 and 254
correspond to gain compensation factors of -25.4db, 0dB, and +25.4dB, respectively). The value 255 shall
be a special value to indicate that the subcarrier does not carry any power. The compensation factor of the
subcarriers outside of the range specified in the gain descriptor shall be 0 dB. To implement the FTU-R Rx
Gain update, the FTU-R shall multiply its current settings of the gain stage in the receiver, for any subcarrier
i in the MEDLEYds set, by its gain compensation factor.

The increase of the aggregate received power at the U-R interface at the transition from PRMPSDds to
MREFPSDds shall not exceed 0.1dB.

NOTE – The VCE may apply the following constraint to accommodate the above requirement:
1 2
∑ | gain compensation factor at the i − th subcarrier | ≤ 1.0233

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