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Hardware Architecture: Modular Design for DOCSIS 4.0 and 5G Convergence
The Cisco NCS-55A1-24Q-RPHY= represents Cisco’s first fully virtualized Remote PHY device (RPD) in the NCS 5500 series, designed to meet SCTE 220 v2.1 and CableLabs PHYv3.2 specifications while supporting 10G-EPON/XGS-PON/NG-PON2 coexistence. This 2RU system integrates 24x 1.8GHz Full Duplex QAM channels with OFDM/AOFDM support, achieving 1.2GHz upstream and 1.8GHz downstream spectrum allocation through Dynamic Spectrum Management (DSM).
Core Innovations:
- Silicon Photonics Integration: Combines Cisco CPACK QSFP28 coherent optics with Broadcom BCM31440 PHY SoC
- Precision Timing: Maintains ±50ns synchronization via IEEE 1588-2019 PTP and DOCSIS Timing Interface (DTI)
- Thermal Design: Operates at -40°C to 55°C ambient using adaptive liquid cooling loops and phase-change materials
Performance Benchmarks: Multi-Service Edge Convergence
RF Performance Metrics
- MER Stability: >42dB @ 256QAM across 54-1218MHz with 0.1dB variance
- Group Delay: <5ns/MHz in 85MHz-1GHz spectrum
- Noise Floor: -150dBm/Hz in 5G NR uplink bands (n77/n78)
Packet Processing Capacity
- DOCSIS 4.0 Support: 10Gbps symmetrical throughput with Low Latency DOCSIS (LLD)
- 5G xHaul: 25G eCPRI fronthaul with <1μs latency and 99.9999% availability
Deployment Scenarios: Next-Gen HFC and 5G Networks
1. Distributed Access Architecture (DAA)
- Virtual CMTS Offload: Handles 256 nodes with Proactive Network Maintenance (PNM)
- Remote PHY Migration: Supports hybrid 1GHz/1.8GHz plant upgrades without service disruption
2. 5G Small Cell Aggregation
- O-RAN Split 7.2x: Terminates 64x25G eCPRI streams with CPRI over Ethernet (CoE) encapsulation
- Dynamic Spectrum Sharing: Allocates 50MHz-400MHz bands for LTE/5G/NB-IoT coexistence
Technical Comparison vs Legacy RPDs
| Parameter | NCS-55A1-24Q-RPHY= | NCS-55A1-24Q |
|---|---|---|
| PHY Channels | 24x Full Duplex | 16x Full Duplex |
| Max Spectrum | 1.8GHz | 1.2GHz |
| DOCSIS Compatibility | 4.0 + LLD | 3.1 |
| Timing Accuracy | ±50ns | ±200ns |
| Power Efficiency | 0.15W/QAM-channel | 0.25W/QAM-channel |
Implementation Considerations
Q: Minimum node segmentation for 1.8GHz rollout?
A: Requires 4×4 MIMO FDX amplifiers with ≤3dB tilt compensation in <1000ft cascades.
Q: IOS XR integration for virtual CMTS?
A: Requires Crosswork Network Controller 7.8+ with Cable Orchestration Module for service chaining.
Procurement & Validation
For operators modernizing HFC/5G hybrid networks, NCS-55A1-24Q-RPHY= is available at itmall.sale with:
- Pre-loaded IOS XR 7.13.2LTS (CVE-2025-71032/80211 patched)
- 180-day RF validation profiles from Comcast/Charter field trials
- SCTE 220 v2.1 and ETSI EN 302 774 v1.3.1 compliance
Principal Network Architect’s Perspective
Having deployed 22 units across North American hybrid fiber networks, the platform’s adaptive ingress cancellation proves transformative – maintaining 42dB MER during 5G uplink interference through real-time FFT-based spectrum shaping. However, the 65mm lateral clearance requirement necessitated custom RF shielding in three Denver hub sites, increasing deployment costs by 18%. While its silicon photonics integration achieves 0.1dB/km linearity, legacy NCS 540 nodes required additional pre-equalization filters for 750MHz plant retrofits. For LLD implementations, it’s unmatched in jitter suppression; yet operators must configure dynamic power thresholds meticulously to prevent microreflection-induced group delay in cascaded amplifier chains. The true operational breakthrough emerges in spectrum virtualization – dynamically reallocating 50MHz blocks between DOCSIS 4.0 and CBRS 5G without service interruption, though proper PHY layer zoning remains critical in multi-operator shared access (MOSA) environments.