Page 648 - 5G Basics - Core Network Aspects

2 Transport aspects

8.3 PCS receiver

The CPRI signal physical coding sublayer (PCS) is terminated and the 8-bit codes are recovered as specified
by IEEE 802.3.
The K28.5 control character that indicates the beginning of the CPRI hyperframe is replaced by 0x00. The
contents of this byte are ignored on reconstruction of the CPRI signal.
8.3.1 NE at RRH site remote management channel

The network element (NE) at the remote radio head (RRH) site can be managed through the GCC0, GCC1
and/or GCC2 overhead. Protocols for these management channels are outside of the scope of this
Supplement.

8.3.1.1 CPRI channel AIS signal
The CPRI channel alarm indication signal (AIS) is specified as all "1"s in the entire CPRI channel, including its
BFP and BaFN overheads.
Under CPRI signal fail conditions as defined in [CPRI], the CPRI channel is filled with CPRI channel AIS.

8.3.1.2 Replacement signal
Under ODU2r signal fail conditions, or if the OMFI, BFP or BaFN are inconsistent, the egress CPRI signal
should be replaced by the link fault signal.

8.4 OTU2r structure

The OTU2r frame structure is an OTUk (k = 2r) frame structure, which may or may not include the forward
error correction (FEC) area.

8.5 Bit rates and tolerances

The bit rates and tolerances are defined in Table 8-3.

Table 8-3 – OTU2r/ODU2r/OPU2r rates and tolerances

Signal type Nominal bit rate Tolerance
OTU2r 255/238  128  24  3 840 kbit/s ±100 ppm
OTU2r no FEC 239/238  128  24  3 840 kbit/s ±100 ppm
ODU2r 239/238  128  24  3 840 kbit/s ±100 ppm

OPU2r 128  24  3 840 kbit/s ±100 ppm
NOTE 1 – The nominal OTU2r rate is approximately 12 639 085.714 kbit/s.
NOTE 2 – The nominal OTU2r without FEC and ODU2r rates are approximately 11 846 045.042 kbit/s.
NOTE 3 – The nominal OPU2r rate is 11 796 480 kbit/s.
NOTE 4 – Due to the BMP mapping, the OTU2r/ODU2r inherits the clock accuracy of the CPRI client signals at the ODU2r source.
The OTU2r/ODU2r/OPU2r frame period is approximately 10.330 µs.

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