To facilitate the delivery of OOB streams from the headend to the customer-facing CPE via the Remote PHY (R-PHY) architecture,
a solution is needed that delivers the OOB streams to the RPD via the same Ethernet carriers that the rest of the services
traverse. The following sections describe 55-1 OOB approaches to this transport:
Ethernet from the OM device: The OM processes OOB source streams per SCTE-55-1 and outputs datagrams via IP multicast.
CCAP-Core forward as virtrual OM: The CCAP joins and processes streams from OM device per SCTE-55-1 and forwards them downstream
to the RPD.
ATM from STB: The STB send augment ATM upstream packet to RPD per SCTE-55-1, RPD build up upstream packet per ARPD protocol
(version 2) and forward it to CCAP core.
CCAP-Core forward as virtrual ARPD: The CCAP receive 55-1 packet via UEPI and forwards them upstream to the NC.
The Out-of-Band Modulator (OM) handles the receiving of OOB source data streams and creating a multiplexed signal in accordance
with OOB 55-1. The MPEG transport stream, containing the OOB is IP multicast using the UDP to the CCAP Core over an Ethernet
Each OM can output only a single OOB multiplex. Hence, a CCAP Core may receive OOB streams from multiple OMs. Each of these
streams is intended for a different set of RPDs.
OM2000 does not include null frames in its Ethernet output stream. The OM provides an output of non-null packets in its Ethernet
output transport streams. Hence, the downstream QPSK modulator should insert nulls when necessary. The Remote PHY device inserts
null packets as necessary to maintain the required module rate of the OOB 55-1 downstream QPSK channel. The downstream modulator
need not maintain precise inter-packet timing. The modulator can effectively insert null packets wherever necessary without
checking for excessive data packet displacement.
Each virtual ARPD uses a unique source IP address and a unique destination UDP port in packets that are sent to the NC. The
NC relies on IP address and UDP port to identify the ARPD from which the traffic is arriving.
Using GCP, the CCAP Core configures the attached RPDs with the appropriate ARPD source ID, RF port ID, and demodulator ID
corresponding to each UEPI tunnel. The RPD uses this information when forming the ARPD datagram.
The RPD aggregates multiple physical demodulators into a single virtual ARPD demodulator ID.
The RPD also supports power level setting of the OOB 55-1 FDC in a range of -7 dBc to 0 dBc relative to the 256-QAM level,
in 0.2 dB steps.