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:

For downstream:

• 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.

For upstream:

• 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 link.

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.

To support the orderly transition of set-top boxes to a higher frequency, the SCTE 55-1 forward data can be carried on two forward channels with distinct frequencies. The data content sent on both channels is identical.

The RPD can support two SCTE 55-1 forward channels on any of its downstream RF port.

In the video headend, the OOB 55-2 Controller maintains all interfaces with the existing applications and services but contains only a subset of the functions available with the existing 55-2 Modulator/Demodulator. The remaining functions are moved to the RPD.

The OOB 55-2 Remote PHY solution places components necessary for performing ATM slot receipt acknowledgement within the RPD, and all other components of the OOB 55-2 MAC located in the 55-2 Controller where feasible. The OOB 55-2 Controller handles the configuration and monitoring of 55-2 specific functions within the RPD. Some monitoring is also included in the upstream data packets sent by the RPD to the 55-2 Controller.

The current 55-2 Digital Home Communication Terminal (DHCT) service group sizes are more than 10,000 DHCTs, versus the expected RPD DHCT counts which can be 1000 or lower. For compatibility with existing infrastructure, RPDs are grouped with a single 55-2 Controller as follows:

• Multiple RPDs are bound by operator configuration to a single 55-2 Controller which can service >10,000 DHCTs.

• RPD demodulators are assigned an Upstream Group ID between 0 and 7. All demodulators in the same Upstream Group logically-share the same upstream slot assignments for 55-2 compatibility. Upstream Group ID is equivalent to SCTE 55-2 Demodulator Number, but is zero indexed instead of 1 indexed. Upstream Group ID 0 corresponds to SCTE 55-2 Demodulator Number 1 (R1), Upstream Group ID 7 corresponds to SCTE 55-2Demodulator Number 8 (R8).

• All RPDs bound to a single 55-2 Controller share a single L2TPv3 multicast tunnel for downstream data.

An RPD can incorporate a number of SCTE 55-2 modules, each represented by Oob55d2Module object. The number of SCTE 55-2 Modules is communicated using RPD capabilities. Common parameters for all 55-2 modules are grouped into an Oob55-2Config object.

Each SCTE55-2 module consists of one modulator and one to eight demodulators. The Oob55-2Modulator can be associated with one or more downstream RF ports, and the Oob55-2Demodulator can be associated with zero or one upstream RF ports.

The RPD reports these associations to the CCAP Core.