NR over Cable (NRoC): Converging 5G NR with DOCSIS Cable Networks

NR over Cable (NRoC) is an emerging architecture that delivers 5G New Radio (NR) signals over existing cable infrastructure. Led by CableLabs and operators like Charter and Rogers, NRoC aims to overlay 5G wireless technology onto the widely deployed hybrid fiber-coax (HFC) networks  . This approach can vastly expand capacity and drive fixed–mobile convergence by utilizing cable’s coaxial plant for 5G, rather than deploying entirely new fiber or radio sites  . In this report, we examine NRoC’s architecture, core technologies, deployment models, and its role in unifying DOCSIS cable systems with 5G. We also compare it to traditional DOCSIS and 5G architectures, discuss use cases (from residential broadband boosts to mobile xHaul and private 5G), address technical challenges, survey the vendor ecosystem and trials, and highlight relevant standards.

NRoC Architecture: 5G Over the HFC Network

HFC Network Overview: Cable operators deliver broadband via HFC networks, where optical fiber extends from the headend out to neighborhood nodes, and coaxial cable carries RF signals from each node through line amplifiers and splitters to homes (each with a cable modem)  . The CMTS (Cable Modem Termination System) at the headend traditionally generates downstream RF (e.g. TV channels, DOCSIS data carriers), which is converted to light for fiber transport and then back to RF at the node, propagating over coax to serve dozens or hundreds of subscribers (see Figure 1). In the return path, upstream signals from cable modems travel over coax to the node, then back via fiber to the CMTS. This shared-medium architecture underpins DOCSIS broadband networks.

Figure 1: Simplified HFC network architecture. Fiber nodes (gray) convert optical signals from the headend to RF over coax, which is distributed through amplifiers and splitters to subscribers’ homes (gray houses). NRoC leverages this existing HFC topology by overlaying 5G NR signals onto the coax segment above the DOCSIS frequencies. (Source: Wikimedia Commons, public domain)

Overlaying 5G NR on Coax: NRoC introduces a 5G radio overlay on the coaxial portion of the HFC plant, using spectrum above the DOCSIS band. Current DOCSIS 4.0 deployments use up to ~1.2 GHz of coax spectrum (with Extended Spectrum DOCSIS targeting 1.8 GHz) for broadband service. NRoC proposes to operate 5G NR in frequencies beyond that – potentially in the 3–5 GHz range – on the same coaxial cable  . In other words, DOCSIS would continue using sub-1.2 GHz spectrum, while 5G signals occupy a new high-frequency band on the coax . Much like DSL used higher frequencies on copper telephone lines for data, NRoC carves out a new coaxial spectrum “lane” for 5G that does not interfere with cable’s existing video and data channels  .

To enable this, several key components and architectural adaptations are required:

• 5G Base Station at the Node: A 5G radio unit (RU) is deployed at or near the fiber node (the coax network ingress point). This RU generates and receives 5G NR waveforms, effectively acting as a small 5G base station (gNodeB) for the coax-served area  . Rather than radiating over the air, the RU’s output is coupled into the coaxial network (as if the coax were the “antenna”). In CableLabs’ vision, “the idea is to overlay 5G on the coax,” taking advantage of the node’s location (with power and backhaul readily available) to inject 5G signals into the cable plant  . This effectively transforms the coax distribution into a wired 5G cell covering all cable modems on that node’s coax segments.

• High-Frequency Coax Components (DAA, R-PHY/R-MACPHY): Because NRoC operates in new high bands, the coax infrastructure may require upgrades. Traditional cable amplifiers and passives are designed for ~1 GHz; NRoC demands amplifiers capable of passing 3–5 GHz and handling 5G’s TDD signals . A new type of broadband amplifier is needed that can amplify legacy DOCSIS below 1.2 GHz in frequency-division duplex (FDD) mode, and also operate in TDD mode above 1.2 GHz for the 5G overlay  . Designing such dual-band, time-synchronized amplifiers is considered a “Herculean effort” by engineers , but it’s central to NRoC. CableLabs member Technetix (a coax RF equipment vendor) is reportedly working on early versions of these NRoC amplifiers .

NRoC dovetails with the cable industry’s Distributed Access Architecture (DAA) initiatives. In DAA, portions of the cable headend functions are moved out closer to subscribers (to nodes or remote cabinets) to improve performance. The two main DAA flavors are Remote PHY (R-PHY) – where the node contains the PHY layer, converting digital fiber streams to RF – and Remote MAC/PHY (R-MACPHY) – where both MAC and PHY layers reside at the node  . Either approach shortens the coax length and enables digital fiber links, which is advantageous for NRoC’s high frequencies. In fact, 5G and cable DAA architectures have parallels: “5G networks already run fiber to the radio and HFC networks using DAA already run fiber to the node”  . A cable node could thus double as a 5G small-cell site in the NRoC model .

Remote PHY nodes: In an R-PHY deployment, the node outputs RF (up to 1.2 GHz for DOCSIS 4.0 today). To add NRoC, a Remote Radio Unit module (5G RU) might be added to the node (for example, in a Generic Access Platform node – see below), injecting 5G RF above 1.2 GHz. The RU could share the coax via an RF combiner so that one coax cable carries both DOCSIS QAM/OFDM channels and 5G NR signals. Meanwhile, the 5G baseband (DU/CU) could be located at the headend or cloud, connecting to the RU over fiber (e.g. using an O-RAN fronthaul link). This essentially uses the DAA node as a strand-mounted 5G remote radio head.

Remote MAC/PHY nodes: In R-MACPHY (standardized via CableLabs’ Flexible MAC Architecture), the node is even smarter – it hosts the DOCSIS MAC and PHY, and often has general-purpose compute. An R-MACPHY node could potentially integrate the entire 5G gNodeB (DU/CU+RU) on-site. This might simplify local coordination between DOCSIS and 5G and reduce fronthaul latency. Whether R-PHY or R-MACPHY, the Generic Access Platform (GAP) standard from SCTE facilitates this modularity: GAP defines a common node housing with slots for service modules (DOCSIS, PON, or wireless). Vecima’s new GAP node, for example, can accept plug-in modules for DOCSIS 4.0, PON, and eventually 5G (NRoC)  . Such nodes are being built with 4 GHz+ RF capabilities to support the NRoC roadmap  .

• Customer Premises Equipment (CPE): On the subscriber end, NRoC envisions a new class of cable CPE that can receive and transmit both DOCSIS and 5G signals. In practice, this could be a hybrid cable modem + 5G UE gateway. The NRoC CPE would still connect to the coax jack, but internally it contains the “guts” of a 5G device (similar to a phone or fixed wireless unit) alongside the DOCSIS modem  . In downstream, it would demodulate the high-frequency 5G NR signal from coax; upstream, it would transmit 5G NR uplink bursts into the coax (timed to the TDD slots). One industry source described it as “squeezing in the guts of a mobile phone radio” into the cable modem  . This could be an integrated home gateway offering both standard cable broadband and 5G-based connectivity. Notably, these CPEs might also create an in-home 5G small cell – for example, using the cable operator’s 5G spectrum (like CBRS) to directly serve the user’s mobile devices. (Initial NRoC trials seem focused on using the coax link primarily as a fixed connection, but the hardware could conceivably broadcast 5G Wi-Fi-like coverage in the home as well.)

NRoC Signal Flow: In summary, a likely NRoC architecture is: 5G core and baseband (CU/DU) at the cable hub → fronthaul over fiber to the 5G RU at the node (or a fully integrated gNB at node) → 5G RF over coax through new amplifiers → 5G/Cable CPE in the home. All the while, traditional DOCSIS 3.1/4.0 signals continue to flow below 1.2 GHz to conventional cable modems. The coax segment essentially becomes a dual-use medium, carrying both DOCSIS and 5G NR in parallel. As Charter’s Connectivity EVP explains, “HFC is pretty ubiquitous, so for a reasonable amount of money, you can add some components and allow it to act as one giant 5G radio”  . Figure 2 illustrates one variant of NRoC: here the 5G gNB is split, with a central baseband (CU/DU) at the headend and a radio unit at the fiber node injecting 5G into coax; the CPE behaves as a 5G UE.

Figure 2: Example 5G-over-Cable architecture (Air5 concept). A 5G gNodeB is distributed: the Central Unit (CU) and Distributed Unit (DU) reside at the headend or cloud data center, connected via fiber fronthaul to a Radio Unit (RU) at the fiber node. The RU injects 5G NR signals into the coax network, where upgraded cable amplifiers pass the high-frequency, TDD signals. At the home, a 5G-enabled cable CPE receives the NR signal over coax (acting like a UE). The CPE also supports regular DOCSIS on the lower spectrum. This architecture leverages existing HFC fiber nodes and coax for 5G coverage, converging cable and wireless networks  . (Source: Air5 via LightReading )

It’s worth noting that multiple architectures are being explored. One approach (as above) feeds 5G directly to each home via coax and a 5G-capable modem. Another approach uses the coax plant to backhaul strand-mounted 5G small cells: for instance, placing a CBRS 5G antenna at the node or on the aerial coax and using the node’s fiber connectivity to carry data back to the core. In that case, the 5G RF is radiated over the air from the node (not over the coax beyond the node). Doug Dawson clarifies that despite the “Radio over Coax” name, Charter’s initial goal is indeed to “feed a CBRS transmitter at the pole” (node), not to replace the last drop coax to the home  . In practice, cable operators could deploy NRoC in multiple ways: coax as a distribution medium to the home and/or coax as a backhaul link to radios. The unifying idea is that the cable network becomes a converged platform carrying 5G signals in some form. As an industry source put it, “it allows fixed and mobile to use the same platform” .

NRoC vs Traditional DOCSIS & 5G Architectures

NRoC brings together elements of both cable and cellular networks. It’s helpful to compare how it stacks up against traditional DOCSIS architecture on one hand and standard 5G wireless architecture on the other, noting the advantages and trade-offs of each:

• Physical Medium: Traditional DOCSIS uses coaxial cable as a guided medium, whereas 5G uses wireless radio propagation. NRoC interestingly uses the wired coax medium for a wireless protocol. By sending 5G OFDM signals through coax, NRoC can avoid the path loss and interference of wireless links, potentially delivering very high SNR connections to each home. It essentially creates a fixed-wireless access link without the “wireless”, reusing the coax. This yields reliability and consistency benefits (less fading, no weather or distance attenuation issues within the coax segment), though it confines mobility – devices must connect via the coax or a local hub, not freely over-the-air as in a cellular network.

• Spectrum and Capacity: A classic DOCSIS 3.1/4.0 plant might use up to 1.2 GHz of spectrum for downstream (with 192 MHz OFDM channels) and up to 204 MHz for upstream (or more with Full Duplex). 5G NR, by contrast, can operate on channels up to 100 MHz (sub-6 GHz bands) or more, and can aggregate multiple bands. NRoC significantly expands available spectrum on coax by adding several GHz of new bandwidth for 5G use  . Industry reports suggest NRoC could extend coax use up to 4 or even 5–6 GHz  . This extra spectrum could translate to multi-gigabit capacities per node. For example, a 5G NR carrier at ~3.5 GHz (like CBRS Band n48) with 100 MHz bandwidth can deliver ~1 Gbps per sector under ideal conditions; multiple such carriers or wider bandwidth could scale that higher. NRoC’s capacity gains are comparable to the next generation of DOCSIS: one analysis noted NRoC “may provide around the same or slightly higher speeds as DOCSIS 5.0” (the anticipated successor to DOCSIS 4.0) . The trade-off is that using higher frequencies on coax shortens reach – coax attenuation increases with frequency. This can be mitigated by DAA (fiber deep) and possibly by using node+0 architecture (no amplifiers after the node) so that coax runs are very short. Indeed, many NRoC discussions assume fiber nodes serving smaller areas so the coax segment is limited to maybe a few hundred meters.

• Duplex Method: DOCSIS has historically used FDD on coax – downstream and upstream have separate frequency bands (and in Full Duplex DOCSIS, specialized echo cancellation allows overlapping bands in 1.2 GHz spectrum)  . 5G NR in sub-6 GHz bands often uses Time Division Duplex (TDD) – the uplink and downlink share a channel and alternate in time slots (frames). NRoC accordingly adopts TDD in the new high band, which necessitates precise timing coordination on the coax. The need for TDD-compatible amplifiers is a direct consequence: cable amps must rapidly switch or accommodate alternating downstream/upstream bursts . This is a notable complexity absent in traditional FDD-based cable systems. However, TDD also offers flexibility: the downstream/uplink capacity split can be adjusted dynamically via the 5G frame configuration. This could be beneficial for, say, allocating more upstream capacity on demand (something static FDD splits struggle with). In effect, NRoC can enable a more adaptive duplexing regime on coax akin to wireless networks.

• Network Topology and Sharing: A standard cable segment is a shared medium – one transmitter (CMTS) serves many modems, and modems take turns on upstream via a scheduling protocol. Similarly, a 5G base station serves many UEs with scheduled times/frequencies. In this sense, NRoC preserves the point-to-multipoint nature of cable but now uses 5G’s advanced air interface to coordinate it. Both DOCSIS and 5G use OFDM modulation and flexible subcarriers, so there is technical kinship at the PHY layer . A major difference, however, is in MAC and scheduling: DOCSIS uses a request-and-grant mechanism with minislot maps, whereas 5G NR uses a frame scheduler with dynamic per-TTI assignments. 5G’s MAC scheduling is faster (1 ms intervals) and can incorporate QoS and MIMO layers, potentially improving latency and multi-user efficiency for the coax segment. On the other hand, DOCSIS is already optimized for cable’s noise and burst profiles, whereas 5G might need tuning to handle coax-specific issues (like impedance mismatches or group delay variations). Latency in NRoC could improve, since 5G NR has shorter frame scheduling (∼1 ms) than DOCSIS 3.1 (which even with Low Latency DOCSIS software is ~5–10 ms typical)  . NRoC’s 5G link might thus reduce last-hop latency for applications like gaming – though overall latency will also depend on the core network routing (5G core vs. legacy cable routing; see “Convergence” below).

• Core Network and Convergence: In a traditional cable setup, the CMTS is essentially a layer-2/layer-3 router bridging modems to the internet via the operator’s IP network; subscriber management is done via DHCP/TFTP and provisioning systems (separate from any mobile core). In 5G, the gNB connects to the 5G Core (5GC) which handles authentication, mobility, and session management for UEs. NRoC offers an opportunity to converge the core: cable operators could choose to route NRoC traffic through a 5G Core network, treating the cable modems (or attached customer devices) as 5G subscribers. This would enable true fixed–mobile convergence with common user identities, policy control, and seamless services across wired and wireless access  . For example, an operator could implement “follow-me” service where a user’s session moves between coax (at home) and mobile 5G (on the go) using the same core and credentials  . However, integrating the 5GC is a non-trivial shift for cable systems. As one cable engineering exec noted, using a 5G Core for provisioning cable services would be “incompatible with anything the industry has done to this point”, though “it’s not a bad idea” as a long-term convergence goal  . Initially, NRoC might be deployed with a more familiar setup (keeping the cable broadband on a CMTS/IP core and using 5G PHY/MAC only), before evolving to deeper convergence at the core.

• Deployment Complexity and Cost: Deploying traditional 5G (for a cable operator entering wireless) usually means acquiring spectrum, building many small cells or towers, and running fiber to each – a capital- and labor-intensive endeavor. Traditional DOCSIS upgrades (e.g. to 4.0) involve upgrading amplifiers, nodes, and CPE – also complex and costly in its own way. NRoC attempts to leverage existing assets of the cable plant to serve wireless needs, potentially lowering deployment costs for certain scenarios. For instance, Charter highlights that with NRoC, it can turn “neighborhood HFC nodes into small cell sites” very cheaply – “at any node for a significantly lower cost than adding a traditional small cell site,” since no new fiber or backhaul is needed  . Coax nodes are already ubiquitous (cable passes ~90% of U.S. homes), so each node is a ready-made location for wireless capacity injection. The trade-off is that to unlock this capability, extensive upgrades to coax electronics are required (new node hardware, new amps, new CPE) and standards need to be developed. NRoC essentially shifts costs into upgrading the cable network, but avoids some costs of standalone 5G site deployment.

• Vendor Ecosystem: DOCSIS technology, especially at the cutting edge (D4.0), currently has a limited vendor ecosystem – e.g. only two major silicon suppliers (Broadcom and MaxLinear) for CMTS and modem chips . In contrast, 5G enjoys a broad global ecosystem of chipmakers (Qualcomm, MediaTek, etc.), radio vendors, and open-source efforts. By adopting 5G technology on coax, cable operators hope to tap into this larger ecosystem. “It effectively allows a much broader range of optionality for the future,” said one person familiar with NRoC, noting the ability to attract multiple chip vendors and avoid cable-specific silicon bottlenecks  . This could drive down costs and accelerate innovation. The flip side is that those 5G chips must be adapted for coax use, which may require customization (e.g. different tuners or removal of antennas). Additionally, it introduces new suppliers (mobile core vendors, RAN software vendors) to cable operators who may need to integrate with existing operations. There’s also an ongoing fragmentation risk: if some operators pursue NRoC while others stick to Extended DOCSIS or pure fiber, the industry could splinter its volume, which concerns some cable technologists  . Harmonizing the standards will be key (more on standards in later section).

In summary, NRoC combines aspects of both DOCSIS and 5G: like DOCSIS, it uses coaxial infrastructure and can serve fixed endpoints; like 5G, it uses OFDMA/TDD wireless protocols and potentially a mobile core. It aims to offer the best of both – high capacity and controlled QoS of 5G, delivered over a reliable wired medium that is already in place to millions of locations. The main advantages include capacity expansion, flexible duplex, infrastructure reuse, and a rich vendor ecosystem. The main trade-offs involve significant hardware upgrades (amplifiers, modems), new complexity in managing RF over coax, and the need to reconcile cable and cellular operational models. Table 1 summarizes some key differences:

Table 1 – Traditional DOCSIS vs. 5G vs. NRoC

Aspect Traditional DOCSIS (HFC) Traditional 5G (Mobile) NRoC (5G over Cable)

Medium Coaxial cable (shared, guided) Wireless RF (shared air interface) Coaxial cable for 5G RF (wired “air” interface)

Spectrum Up to 1.2–1.8 GHz (DOCSIS 4.0), FDD split Various bands (sub-6 GHz, mmWave), TDD/FDD Above 1.2 GHz on coax (3–5 GHz typical), TDD

Duplex method FDD (separate downstream/upstream channels); FDX option at 1.2 GHz with echo cancellation  Primarily TDD in sub-6 GHz (dynamic DL/UL); some FDD bands TDD on coax high band (dynamic DL/UL); legacy DOCSIS stays FDD below 1.2 GHz  

Access/MAC Scheduled TDMA (minislot MAPs), 2–10 ms scheduling intervals Scheduled in frames (1 ms subframes), advanced scheduling (MIMO, HARQ) 5G NR scheduling for high band (1 ms frames); potentially faster uplink grants and lower latency than DOCSIS

Topology & Range Fiber node serves 100s of homes via cascaded coax amps (distance few km) Cells serve wireless users in range (hundreds of meters for small cells; km for macro) Fiber-deep node serves homes via short coax (100s of m). Coax reach is shorter at high freq – likely Node+0 or minimal amplifiers.

CPE/Device Cable modem/gateway (fixed installation) Mobile User Equipment (smartphones, CPE, IoT) Hybrid cable modem with 5G UE radio; possibly indoor 5G small cell in CPE. Fixed install with optional mobile device connectivity.

Core Network IP network + CMTS, provisioning servers (not mobility-aware) 5G Core (AMF/SMF, etc.), SIM-based auth, mobility management Option 1: Use existing cable IP core for internet access; Option 2: integrate with 5G Core for unified authentication, mobility, slicing . Long-term FMC vision to use 5G Core for both fixed and mobile .

Deployment Upgrade HFC plant (nodes, amps, CMTS) and CPE; reuse coax, headends New cell sites (or collocated on existing towers), fiber backhaul, new spectrum licensing, RAN equipment and core deployment Upgrade HFC plant (nodes, amps, CPE) and deploy 5G baseband software; reuse coax for “fronthaul”; fewer new physical sites (nodes double as cells). Leverages existing power/backhaul at nodes  .

Capacity & Throughput Multi-Gig downstream per node (DOCSIS 4.0 ~10 Gbps DS aggregated); upstream 1–2 Gbps (in 1.2 GHz FDX) Varies: small cell sub-6 GHz ~1–2 Gbps per cell (100 MHz), macros can be higher with mid-band + mmWave; multi-Gig achievable with carrier aggregation Multi-Gig aggregated per node (multiple 100 MHz 5G carriers over coax). NRoC could match or exceed DOCSIS 4.0 capacity with additional spectrum . Highly localized capacity (per node).

Key Advantages Mature tech, ubiquitous coax footprint, dedicated spectrum (no external interference), known upgrade path (DOCSIS 4.0) Mobility, wide coverage, many vendors, rapid evolution (5G Advanced), supports low-latency URLLC and massive IoT Reuses existing plant (no new fiber to home), huge new spectrum on coax, dynamic duplex, taps global 5G ecosystem , enables fixed–mobile convergence (one network for both) .

Key Challenges Spectrum ceiling (1.2–1.8 GHz), limited upstream in FDD, few silicon suppliers, plant upgrades costly (node splits, fiber deep needed) High deployment cost for densification, need spectrum licenses, interference management, power and backhaul for many sites Coax hardware must handle high freq & TDD (new amps) , CPE more complex (5G+DOCSIS), not inherently mobile coverage (serves fixed points unless combined with Wi-Fi/small cells), integration with 5G core and standards still in progress.

Use Cases and Applications of NRoC

NRoC’s ability to blend 5G and cable opens a variety of use cases that leverage the strengths of both. Here we outline key applications:

1. Residential Broadband Enhancement (10G Home Internet)

One primary use case is boosting residential broadband beyond the limits of DOCSIS alone. Cable operators can use NRoC to augment home internet capacity and performance. By allocating a 5G-based channel on coax, an operator could deliver additional downstream throughput to a home on top of what DOCSIS provides, or dedicate the 5G channel to certain services (e.g. low-latency traffic or IPTV). For example, NRoC could enable multi-gigabit speeds by utilizing wide 5G NR channels at high modulation, helping operators reach their “10G” broadband goals. It also introduces dynamic capacity – unlike the fixed bandwidth split of DOCSIS, a 5G coax channel could flexibly serve asymmetric traffic as needed (useful for periods of high upstream demand, gaming, video calls, etc.).

Another aspect is improved latency and QoS for home services. 5G NR was designed with features like ultra-reliable low-latency communication (URLLC) and cellular QoS Class Identifiers (QCIs)/5QI flows, which can be mapped to prioritize traffic. Running interactive applications (AR/VR streaming, cloud gaming) over the 5G overlay could reduce lag compared to the traditional DOCSIS path (especially if the 5G path interfaces with a 5G core that supports low-latency routing). CableLabs’ work on Low Latency DOCSIS shows sub-5ms is achievable on HFC , but that requires software upgrades; NRoC provides an alternate route to low latency using 5G’s purpose-built design.

For customers, this might be seamless – the cable gateway could bond DOCSIS and 5G flows or use one as a primary and the other as supplementary. In effect, the home gets a converged wireline+wireless pipe. This could be marketed as enhanced “5G-powered” cable broadband. Notably, if the operator also runs a 5G core, the home gateway could be authenticated similarly to a mobile device, allowing unified subscriber management. This ties into the convergence vision: a 5G Cable Residential Gateway (5G-RG) in the home that registers to the mobile core and provides fixed internet service – a concept already being standardized in 3GPP and CableLabs convergence efforts (see Standards section).

2. Mobile xHaul (Backhaul and Fronthaul over Cable)

A major opportunity for NRoC is to support mobile network build-out – specifically, serving as xHaul (backhaul, midhaul, or fronthaul) for 5G small cells. Cable companies can leverage their dense HFC networks to deploy and connect cellular radio equipment, accelerating mobile coverage and offload in their footprint.

• Strand-Mounted Small Cells (CBRS Offload): The most direct use case, championed by companies like Charter, is to deploy 5G small cell radios at cable node locations or along the aerial plant to offload mobile traffic. Charter acquired Priority Access licenses in the 3.5 GHz CBRS band and has begun rolling out small cells in high-usage areas  . With NRoC, each existing cable node can be “transformed into a small cell site” at low incremental cost  . The coax strand provides mounting, power (cable plant power supplies), and critically, backhaul via the fiber that already feeds the node. In an NRoC deployment, a 5G radio unit (for CBRS or C-band, etc.) at the node could plug into the node’s network interface – possibly even using the DOCSIS plant or the new coax NR channel for backhaul. Charter has noted that NRoC would “take advantage of legacy HFC assets such as power and backhaul” – “it’s got everything that you need” at the node  . By avoiding new fiber runs, Charter says NRoC “can transform the cost of small cell deployment”, making dense networks economically feasible  . In practice, this might mean a small integrated 5G antenna-radio unit on the strand, fed by either a high-split DOCSIS backhaul or by the aforementioned 5G-over-coax channel from the node.

• Fronthaul for Distributed RAN: Another variant is to use the cable network to carry fronthaul signals (e.g. eCPRI) for 5G radio heads. CableLabs and SCTE have explored “5G fronthaul over DOCSIS” – transporting radio samples or low-layer splits over a DOCSIS network  . While challenging due to stringent latency and sync requirements, it’s conceivable that a DOCSIS 4.0 plant with Low Latency DOCSIS and precise timing could carry O-RAN fronthaul to an RU at the node. NRoC’s approach is slightly different (it transports the RF via coax rather than digitized samples via DOCSIS frames), but one can imagine a hybrid: for example, an O-RAN Distributed Unit (DU) at the headend and an RU at the node, with the digital fronthaul running over the fiber or even over a reserved portion of the DOCSIS network. Indeed, the Air5 architecture in Fig. 2 shows a split gNB with fiber fronthaul between DU/CU and RU. The cable plant could potentially carry that fronthaul either by a dedicated wavelength or by using the existing digital fiber link of a DAA node. The benefit is the cable node and coax bring the RU physically close to users (reducing wireless distance). This use case overlaps with the small cell one – essentially it’s how you’d implement small cells via a centralized baseband.

• Macro Cell Backhaul: Cable operators can also offer their HFC network as backhaul links for traditional mobile macro sites or enterprise 5G networks. In areas where fiber to a cell tower is unavailable, the cable coax network (with its new spectrum or even just DOCSIS) could serve as a high-speed backhaul. DOCSIS 3.1 can already deliver hundreds of Mbps upstream which may suffice for a 5G macro’s needs; future DOCSIS 4.0 symmetric service or an NRoC channel could offer gigabit backhaul. The advantage is quick connectivity using existing plant. The challenge is ensuring QoS and synchronization on a shared medium. NRoC could dedicate a portion of its 5G channel capacity specifically for backhaul traffic, isolated from residential traffic by 5G QoS slicing.

• Fronthaul to Indoor DAS/Small Cells: In venues like stadiums or large buildings that have cable wiring, NRoC could feed indoor 5G radios. For instance, a sports arena with coax distribution (for TV) could utilize that coax to drive 5G antennas throughout the facility (like a DAS – distributed antenna system – but using 5G tech). This is speculative, but leveraging pre-wired coax in buildings could avoid pulling new fiber for indoor 5G systems.

Overall, NRoC extends the cable operator’s reach into wireless by turning the HFC plant into an instant infrastructure for cellular densification. It complements strategies like MVNO (which cablecos use to offer mobile service via partnerships) by enabling the cable operator to offload mobile data onto their own network at the last mile. Charter and Comcast are already deploying CBRS small cells to offload MVNO traffic in some cities . NRoC can turbocharge this by making deployment plug-and-play at each node. It effectively marries the cable node to the 5G cell site concept.

3. Private Networks and Enterprise Solutions

NRoC can also play a role in enterprise and private 5G networks, especially in venues or campuses where the cable operator has a presence. Some potential scenarios:

• Multi-Dwelling Units (MDUs) and Campus Environments: Many office campuses, apartment complexes, or college campuses are already wired with coax for cable service. NRoC hardware could be installed to create a private 5G network that runs over that coax plant. For example, an operator could install a 5G RU in the basement telecom room (where coax distribution starts) and use building coax to propagate 5G to each office or apartment via a small indoor antenna or directly to a 5G cable modem. Vecima explicitly notes that its 4 GHz-capable GAP node is “optimized for multiple-dwelling unit (MDU) and enterprise applications”, and can be deployed in various modes including NRoC . This suggests cable vendors see a market for using NRoC to serve business campuses or MDUs with dedicated 5G capacity. A private 5G core could be used in tandem, giving the enterprise control over its own slice of the network.

• Industrial IoT and Sensor Networks: With NRoC providing a parallel data path across the HFC, one idea is to dedicate that path to IoT sensor traffic or out-of-band management. The high frequencies could support technologies like NR-Light (RedCap) for low-power devices. Charter has mused that the “extra bandwidth could be used for new products, such as supporting communications with IoT sensors.”  . A cable operator could run a private NB-IoT or LTE-M network over coax for utilities, smart city sensors, etc., without impacting regular internet service.

• Satellite Connectivity Backhaul: An intriguing use case mentioned by analysts is using NRoC to “distribute earthbound traffic from direct-to-satellite cellular communications.”  . As satellite-to-phone services (like AST/SpaceMobile or Lynk) emerge, the idea is that when a satellite connects to a phone, the backhaul of that traffic could be handed off to a local cable plant when the user is in range. The NRoC channel could carry that traffic within neighborhoods to gateways. Though speculative, it shows the breadth of applications when you have a second data path in the cable plant.

• Converged Business Services: Cable operators already sell business internet and Ethernet services. With NRoC, they could offer 5G coverage as a service on top. For example, a factory could get wired broadband plus on-premises 5G for AGVs (automated vehicles) or wireless sensors, all delivered by the cable provider over hybrid infrastructure. The operator could manage a 5G core that interconnects with the factory’s network. Because NRoC shares the same cable fiber nodes that deliver business internet, it’s convenient to overlay.

In summary, private 5G and enterprise IoT networks are a promising adjunct use case for NRoC, leveraging coax in places fiber or Ethernet might not be readily available to every desired radio location. By converging services, cablecos can position themselves as one-stop connectivity providers, delivering both wired and wireless solutions with unified SLAs.

4. Enhanced In-Home Experiences

NRoC could also indirectly improve consumer wireless experiences inside the home. If the cable gateway has a 5G radio (as envisaged), the operator might use it to create an in-home 5G network that links to consumer devices. While Wi-Fi is predominant for home networking, future AR/VR or ultra-low latency applications might benefit from 5G’s scheduling and QoS. A cable operator could deploy a “5G LAN” in the home by enabling the NRoC modem’s 5G transceiver to act as a local small cell (using either licensed or unlicensed 5G bands). For instance, using CBRS, the gateway could provide coverage that seamlessly hands off to the outdoor CBRS network – improving indoor mobile reception and allowing the home’s capacity to be shared by mobile devices. This is a more futuristic use case and depends on regulatory allowance (e.g. using CBRS indoors by subscribers) and chipset support in consumer devices (phones supporting the operator’s band). But it underscores the convergence theme: the line between fixed and mobile access blurs, with the home gateway becoming part of the mobile network.

Technical Challenges of NRoC

While NRoC is promising, it introduces significant technical challenges that must be overcome:

• RF Interference and Coexistence: Although DOCSIS and 5G channels are in separate frequency bands on coax, careful engineering is needed to prevent interference and leakage. Coax plant components (taps, splitters, amplifiers) must have good isolation so that the strong downstream DOCSIS signals don’t bleed into the sensitive 5G upstream spectrum or vice versa. Filters will be required at the diplex boundaries (around 1.2 GHz) to ensure a clean separation . Ingress and egress are concerns too: coax is shielded, but at 3–4 GHz even small connector leaks could radiate. If the operator’s 5G overlay uses licensed spectrum (e.g. CBRS), any leakage could interfere with nearby radios or violate regulations. Conversely, external RF noise in those bands could enter the coax if shielding isn’t perfect, raising the noise floor for NRoC. Maintaining high shielding integrity and perhaps using improved coax cables/connectors in the home (which historically were only certified to ~1 GHz) will be important. Technologies like directional couplers and isolation amplifiers may be needed at certain points to segregate legacy and 5G signals. CableLabs has acknowledged the need for the NRoC system to “coexist with DOCSIS” or serve as an extension, meaning extensive testing for interference issues  .

• Spectrum Planning and Signal Quality: Sending signals up to 4–5 GHz over coax pushes the limits of the legacy plant. Attenuation (dB loss per distance) is much higher at these frequencies – coax that has, say, 6 dB attenuation at 1 GHz might have 20+ dB at 4 GHz over the same length. This drastically reduces reach or requires more amplification. Full-band amplifiers from 50 MHz to 5 GHz with flat gain are difficult; likely the new amps will treat the bands separately (FDD low band and TDD high band). There’s also group delay and tilt to consider – coax and amps may introduce frequency-dependent latency or gain slope that needs equalization. 5G OFDM is robust, but if the coax response is poor, subcarrier orthogonality can be affected. The NRoC gear will need sophisticated RF conditioning (perhaps adaptive EQ or pre-distortion). Additionally, if the operator is also using the 1.2–1.8 GHz range for Extended DOCSIS 4.0 (ESD), they must coordinate that with NRoC plans. One scenario is that NRoC replaces the push to 1.8 GHz DOCSIS: operators might cap DOCSIS at 1.2 GHz and allocate all spectrum above to 5G, avoiding the need for DOCSIS 4.0 amplifiers at 1.8 GHz  . But others may still pursue 1.8 GHz DOCSIS in parallel. In any event, coax spectrum up to several GHz will require new design rules and characterization. CableLabs is even studying pushing HFC to 6 GHz in the future  – likely in context of NRoC. The higher the frequency, the more critical the coax plant condition (oxidized connectors, water ingress, etc., could impact performance at RF extremes).

• Time Synchronization (TDD Coordination): Operating TDD across a distributed coax network requires tight time sync. All RUs (node radios) should align their transmit/receive switch times to a common reference (e.g., GPS or network grandmaster) to avoid interference at boundaries. If coax segments in adjacent nodes leak RF or if any over-the-air reuse is planned, unsynchronized TDD could cause one segment’s downlink to interfere with another’s uplink. Cable networks historically use DOCSIS Timing Protocol or Sync-E over fiber to synchronize remote PHY devices ; a similar approach can distribute timing to NRoC nodes. The DOCSIS network clock can possibly be tied to 5G’s clock (e.g., using PTP IEEE 1588 and timing packets delivered to the node). 5G frames are 10 ms with 10 subframes – the node must adhere to this timeline. Also, upstream scheduling from multiple modems (UEs) on coax needs timing alignment at the node receiver. Today’s cable modems already maintain time offsets to align bursts at the CMTS within a microsecond. This capability can be repurposed: each 5G CPE (UE) will likewise need to adjust timing advance so that its uplink arrives in the correct TDD uplink period at the node. The challenge is ensuring the legacy DOCSIS timing system and the 5G TDD frame timing can be unified or kept stable relative to each other.

• Low Latency and Jitter: To use NRoC for fronthaul or low-latency applications, any added delay in coax must be minimized. Amplifier switching in TDD introduces a small latency (and perhaps jitter if switching isn’t perfectly periodic). The processing in the CPE (which now includes a 5G protocol stack) adds some overhead vs. the simple modem bridging of DOCSIS. If the 5G core is used, packets might traverse a different path (to the 5GC and out) rather than directly to a CMTS and internet, possibly affecting latency. One way to mitigate jitter is to schedule critical traffic in one domain – for example, keep a VR application entirely on the 5G channel and dedicate a slice with guaranteed periodic resources. The complexity comes if traffic needs to move between DOCSIS and 5G channels (multi-path) – then differing latencies could cause reordering. CableLabs’ convergence lab is working on solutions for multi-access steering and switching (ATSSS) which might help manage that.

• Quality of Service and Traffic Engineering: Running two parallel systems (DOCSIS and 5G) means operators must coordinate QoS across them. A user could be using bandwidth on both links – the network should enforce overall service tiers. DOCSIS uses a provisioning system with service flows and QoS parameters, while 5G uses QoS flows and slicing. Mapping these will be important. For instance, a cable subscriber paying for 500 Mbps should get that whether data goes over DOCSIS or 5G or both, without exceeding the cap. This may entail the CPE or core doing traffic splitting intelligently (ATSSS rules could split flows by type – e.g., video over one, web over another). If the 5G channel is shared by multiple homes, the 5G scheduler will ensure each UE gets its share according to priority. This is analogous to how a CMTS scheduler works, but policies need to align. A challenge arises if different homes have different DOCSIS service tiers yet contend on the same 5G cell – the 5G scheduler would need awareness of those tiers to enforce fairness. Such interworking will likely require new control software or convergence policy controllers that orchestrate resource allocation across DOCSIS and 5G domains.

• Device and Network Handovers: In scenarios where the 5G overlay is also providing mobile service (e.g., a phone moving from macro 5G to an NRoC small cell at home), handovers need to be managed. A phone coming onto the coax-based cell might see a very strong signal but the network has to know it’s the same user as their cable account (if a unified core, this is possible). This delves into the converged core challenge – not technical impossibility but operational complexity for service providers not used to mobile handoffs and authentication on their fixed plant.

• Standards and Interoperability: Until formal standards are set, early NRoC deployments will be proprietary or experimental. Ensuring multi-vendor compatibility (e.g., a Technetix amp works with a Vecima node and a CommScope modem with Qualcomm 5G chip) will require industry-wide specs. CableLabs aims to develop NRoC specifications as a “bona fide set of CableLabs specs” once feasibility is proven . These would cover the physical layer, amplification, and perhaps the interface to 5G core. Likewise, in 3GPP, if a “cable friendly” mode or profile is desired, that has to be standardized (Air5 has talked of advocating a “cable branch” in 5G standards  ). Until then, risk of vendor lock-in or integration hiccups is high.

Despite these challenges, the industry is actively addressing them. Prototype systems have already demonstrated feasibility (Charter’s early demos showed 5G over coax working in principle ). The next hurdles are mainly engineering refinements and scale testing. As Jeff Baumgartner observed, “we’ve passed feasibility and are discussing the potential to find and develop a system”  . The coming 12–18 months will likely see these technical issues being worked out through CableLabs trials and supplier collaborations.

Vendor Ecosystem and Trials

Although NRoC is in early stages, a nascent ecosystem of operators and vendors is coalescing around the concept:

• Cable Operators (MSOs): Charter Communications (Spectrum) is the most vocal proponent of NRoC. Charter has a fixed-mobile convergence strategy (it offers Spectrum Mobile service via MVNO and is deploying its own cellular infrastructure in CBRS). Charter’s CEO has hinted at extending HFC spectrum and not stopping at DOCSIS 4.0 , and NRoC aligns with that vision. Charter, along with Rogers Communications (a Canadian MSO), partnered with CableLabs to launch CableLabs North in late 2023 specifically to develop 5G-over-cable technologies  . Rogers, being a major wireless operator as well, sees leveraging its coast-to-coast HFC plant to “accelerate [its] 5G wireless network” as a strategic move  . Both Charter and Rogers emphasize that NRoC is additive, not a replacement – they continue to invest in DOCSIS 4.0 and fiber upgrades, but view NRoC as a parallel convergence path  . Comcast, another giant MSO, has been quieter publicly on NRoC, focusing on its own FDX DOCSIS 4.0 rollout. However, Comcast and Broadcom did discuss extending spectrum to 3 GHz at SCTE Expo, which “appears to fit hand-in-glove with the NRoC concept.”   Comcast’s participation might hinge on how NRoC evolves in CableLabs specs. Other MSOs like Cox or European operators (e.g., Vodafone, which has both cable and mobile assets) are keeping an eye on these developments, likely through CableLabs and SCTE forums.

• CableLabs: As the industry R&D consortium, CableLabs is spearheading research and coordination on NRoC. They have not released a formal spec yet, but as noted, plan to if the project gains traction . CableLabs is also working on broader convergence initiatives (the 10G Lab, etc.) which include running 5G cores alongside cable networks . They see NRoC as one piece of the convergence puzzle, complementing efforts in core network integration and multi-access edge computing.

• Network Hardware Vendors: The companies that supply cable access equipment are gearing up for NRoC:

• Vecima Networks – a Canada-based vendor (which acquired Cisco’s cable access business) – unveiled a new Entra EN3400 Compact GAP Node that is “4 GHz-capable” and explicitly references support for “New Radio over Coax (NRoC)” in its roadmap  . The EN3400 is a modular node that can host R-PHY or PON today and later a 5G module. Vecima’s SVP noted particular interest in 3.65 GHz CBRS for NRoC and confirmed the intent to support it when it “comes to fruition.”   Charter, a Vecima customer for nodes, was cited as a key backer.

• Technetix – a vendor known for cable amplifiers and passives – is rumored to be developing the specialized TDD amplifiers NRoC needs . This is crucial since no off-the-shelf amplifier today handles 5 GHz TDD cable signals. If Technetix or others (CommScope, Teleste, etc.) can crack that design, it will be a cornerstone piece of NRoC deployments.

• Broadcom – the dominant DOCSIS silicon provider – has “unified” DOCSIS 4.0 chips that can do both FDX and ESD (to 1.8 GHz). At Expo 2022, Broadcom and MSOs indicated those chips could be extended to ~3 GHz  . This suggests Broadcom is willing to support higher spectrum if operators demand. Support to full 4 GHz might need a new generation, but it’s on the radar. If Broadcom sees a market, they could develop RF front ends and ADC/DACs optimized for 5G NR waveforms on coax.

• MaxLinear – another chip vendor (with the Puma family) – might also pivot to support NRoC, though they’ve been more focused on standard DOCSIS 4.0 ESD. A lot depends on scale: if NRoC looks to be widely adopted, all silicon vendors will adjust roadmaps accordingly.

• CommScope (Arris) – a major CMTS and CPE supplier – has discussed extended DOCSIS 3.1 testing and is deeply involved in DAA rollouts  . CommScope hasn’t publicly discussed NRoC, but as a leading node/amplifier maker, one can expect they are investigating how their E6000 CMTS or Remote PHY nodes could integrate 5G. They also have a small cell division (via the Airspan acquisition) which could come into play.

• Harmonic – a vendor of virtual CMTS (vCMTS) – similarly may look at how a vCMTS could coexist with a 5G core or share infrastructure. No public info yet, but as a forward-looking company, likely keeping an eye on CableLabs outputs.

• Startups and New Players: Air5 is a notable startup founded by veterans from wireless and cable, aiming “to invent the future of cable by blending DOCSIS with 5G”  . Air5 has developed an architecture (as depicted in Fig. 2) and claims to have solved key integration challenges, creating an internal proof-of-concept and seeking to trial with vendors/operators  . They emphasize developing “integrated products that support both DOCSIS and 5G” for network and home, with a goal of a more seamless design than bolting together off-the-shelf parts  . Air5 sees itself as an evangelist for standards, intending to push its converged approach in both cable and 3GPP forums  . Their leadership includes notable figures (former Ericsson CTO, former Liberty Global CTO, etc.), indicating a serious effort . Air5’s emergence shows the interest in solving NRoC not just within incumbents but also via agile innovators.

• Trials and Deployments: So far, activity has been in labs and limited field demos:

• In May 2024, Charter demonstrated NRoC concepts to the CableLabs board of directors, which was “popular” and was to be followed by a tech committee demo  . This indicates a working prototype exists, likely in a controlled environment.

• Charter executives have hinted at exploring NRoC to “broaden 5G CBRS deployments at lower costs” , and they are actively deploying CBRS small cells in markets like Charlotte, NC (not yet NRoC-based, but setting the stage) .

• Vecima presumably tested its GAP node at 4 GHz to validate RF performance, given they publicly launch it with NRoC in mind.

• CableLabs 10G Lab is likely running multi-vendor trials of convergence scenarios. They had already hosted multiple 5G cores and vRAN systems alongside HFC in a cloud-native setup . The next step is tighter integration of wireless and cable at the access level, and NRoC fits that bill. We may see CableLabs announce more on NRoC trials at upcoming conferences (SCTE Cable-Tec Expo 2025, etc.).

• No large-scale deployment yet (NRoC products are not commercially ready). The timeline mentioned by industry sources is that commercial products are a year or more away as of mid-2024 . So late 2025 or 2026 might see initial rollouts if all goes well.

• Perspective of Traditional Mobile Vendors: It’s interesting that typical mobile infra OEMs (Ericsson, Nokia) are not explicitly in this mix yet. They might see NRoC as a niche or something the cable industry will handle with their own vendors. However, partnerships could form – for example, Nokia has cable modem heritage via Motorola/Arris, and Ericsson has massive 5G expertise. If NRoC opens a market for, say, millions of 5G cable gateways, companies like Qualcomm or MediaTek would be keen to supply the chipsets for those CPE. Indeed, one analyst noted “you’d like to have Qualcomm or MediaTek involved” as cable dives into 5G, to broaden the silicon sources  . We might anticipate those conversations happening behind the scenes.

In summary, the NRoC ecosystem is building through a collaboration of cable operators (demand and testbeds), cable vendors (nodes, amps, CMTS/CCAP), mobile tech suppliers (5G silicon, software), and startups bridging the knowledge gap. Early trials are validating the concept, and suppliers are beginning to advertise NRoC-ready capabilities (like 4 GHz nodes). Within the next 1–2 years, we can expect announcements of field pilots – for example, a city neighborhood where a cable operator trials live 5G-over-coax service to a small set of subscribers, possibly in tandem with CBRS small cell offload. Those results will inform standardization and larger deployments.

Relevant Standards and Specifications

NRoC sits at the intersection of cable and wireless standards. The development and adoption of common specifications will be crucial to ensure interoperability. Key standards relevant to NRoC include:

• 3GPP 5G NR Standards: The foundation of NRoC’s wireless aspect is 3GPP’s 5G NR, defined in the 38-series specifications (38.101, 38.211, etc. for physical layer, MAC, RLC, PDCP, RRC protocols). Release 15 introduced the baseline NR air interface (OFDM, LDPC coding, TDD operation, etc.), which NRoC leverages directly. For example, 5G NR’s flexible numerology and frame structure allow it to be used on a non-mobile medium (coax) with minor modification. The 3GPP Band n48 (CBRS 3.5 GHz) or other bands could be used for NRoC – though if signals are confined to coax, the “band” concept is mostly relevant for the radio hardware; interference management is local. 3GPP Release 16/17 are very relevant for convergence: Rel.16 introduced the concept of 5G for wireline access, known as 5G Wireless-Wireline Convergence (WWC). In 3GPP TS 23.316 and related specs (developed in coordination with Broadband Forum’s TR-456), the standard defines how a cable/DSL/fiber fixed broadband network can integrate with the 5G Core. It introduced network elements like the Wireline Access Gateway Function (W-AGF) which interfaces a Cable Hub to the 5G core, and the notion of a 5G Cable Residential Gateway (5G-CRG) which acts as a 5G UE over a fixed network  . This architecture basically allows a cable modem (residential gateway) to register on the 5G core through an intermediate function that translates cable authentication to 5G authentication. CableLabs has contributed to these specs (they published a Technical Report on 5G wireline convergence architecture). For NRoC, if the operator chooses to use a 5G core for NRoC traffic, these standards ensure that the cable system can appear as a seamless extension of the 5G network. For example, an NRoC CPE could actually be a 5G-RG that communicates via the W-AGF in the headend to the 5G Core’s AMF  . This enables unified subscriber management and mobility anchor, fulfilling the convergence goal. Release 17 and 18 continue to refine convergence and even mention Flexible Duplex enhancements to address uplink latency issues in TDD (which could benefit NRoC by reducing switching delays)  . It’s notable that 3GPP has embraced Fixed-Mobile Convergence as part of 5G’s vision, allowing 5G services to run over non-3GPP accesses like cable – “the 5G standard also supports fixed-mobile convergence architecture — for example, Wireless-Wireline Convergence (WWC).”  . This provides a standards-based path for NRoC to become a truly integrated part of 5G networks, rather than a proprietary overlay.

• CableLabs DOCSIS & DAA Specifications: On the cable side, the Data Over Cable Service Interface Specification (DOCSIS) family is fundamental. DOCSIS 3.1 and DOCSIS 4.0 specs (CM-SP- DOCSIS3.1-Ixx, CM-SP-D4.0) define the physical and MAC layers for cable modems and CMTS. DOCSIS 4.0 comes in two flavors: Extended Spectrum DOCSIS (ESD) up to 1.8 GHz and Full Duplex (FDX) up to 684 MHz shared spectrum. NRoC potentially represents a beyond-DOCSIS-4.0 extension. There is talk that an eventual DOCSIS 5.0 (or DOCSIS 4.1) might target 3 GHz spectrum   – which overlaps with NRoC frequencies. Indeed, the exploration of NRoC has prompted discussion whether to extend DOCSIS to 3 GHz or let 5G have that realm . If NRoC moves forward, CableLabs may incorporate an annex to DOCSIS or a parallel spec that specifies how to transmit 5G NR signals over HFC. We might see a “CableLabs NRoC Specification” emerge, or perhaps updates to the Remote PHY (R-PHY) spec and Flexible MAC Architecture (FMA) specs to accommodate wireless modules. The Distributed CCAP/DAA specifications (like CableLabs CM-SP-R-PHY and the FMA specs for R-MACPHY) already provide a framework to split MAC and PHY. CableLabs could add a standard interface for a 5G RU module in a node (for example, a definition of how a R-PHY Device communicates with a co-resident 5G radio module – perhaps via Ethernet fronthaul or a virtualization interface). Also relevant is the CableLabs Generic Access Platform (GAP) specification (issued via SCTE as a standard for node hardware). GAP is mentioned in context that it “uses a standardized housing and interfaces for service and compute modules… those GAP nodes could also be equipped with 5G small cells.”  . The SCTE | ISBE standard (SCTE 216) for GAP ensures that a 5G module can be physically and electrically integrated.

• SCTE & Industry Standards: The Society of Cable Telecommunications Engineers (SCTE) conducts an annual Cable-Tec Expo with technical papers (we referenced one on 5G Fronthaul over DOCSIS ). SCTE’s standards arm (now part of CableLabs) might publish best practices or standards recommended practices for NRoC deployment (e.g., how to do timing, how to manage interference). One SCTE paper title suggests work on “Enabling 6 GHz Spectrum for HFC”  – which likely touches on NRoC as that’s beyond DOCSIS 4.0’s 1.8 GHz. Additionally, the Broadband Forum (BBF) has been collaborating on wireline convergence (they have TR-456, TR-470 etc. for 5G FMC). The BBF and CableLabs have alignment on 5G-CRG and W-AGF specs, so any cable-specific issues (like mapping QoS or multicast to 5G) might be standardized there.

• Device Certification and Regulation: Cable modems are certified via CableLabs programs for DOCSIS compliance. With 5G radios being added, certification might need to extend to ensure both DOCSIS and 3GPP compliance. The FCC or other regulators might also weigh in: if NRoC uses licensed spectrum (like CBRS PAL), the coax system must adhere to those rules (e.g., CBRS SAS registration if it’s radiating, though if fully contained in coax, perhaps not). There may need to be an understanding that coax leaks are minimal so that using spectrum over coax doesn’t count as “transmission” in regulatory terms. Conversely, if using unlicensed 5G (NR-U) inside coax, interference is less a regulatory issue but ensuring it doesn’t interfere with in-home Wi-Fi (which also goes up to 6 GHz now) could be important – e.g., if a home uses MoCA networking at 1.6 GHz or Wi-Fi6E at 5–6 GHz, the CPE design should isolate these or coordinate channel usage.

• Future 6G Considerations: While not directly a standard yet, looking ahead, 6G discussions emphasize built-in convergence. CableLabs notes that “the industry has new opportunities to reconsider seamless connectivity and convergence” for 6G, hopefully simplifying integration of wireline from the start  . So NRoC might be an intermediate step that influences 6G architecture. If NRoC proves valuable, 6G standards could include a mode for guided media or at least not preclude non-wireless links in RAN design.

In summary, NRoC will be governed by a mixture of 3GPP and CableLabs/SCTE standards. The 5G air interface (3GPP) part is standardized and ready – that’s why NRoC uses “off-the-shelf 5G technologies” and can progress quickly  . The coax-specific adaptations will be new ground for CableLabs and partners to formalize. As Air5 indicated, they will try to push the concept into 3GPP RAN discussions (for example, ensuring 5G has hooks for cable) . Likewise, CableLabs will likely produce an NRoC Technical Report or specification in the CableLabs family (perhaps labeled WR-NRoC if under Wireless or as part of DOCSIS extensions). The convergence of DOCSIS and 5G in standards is a critical enabler – it ensures that down the line a 5G phone and a cable modem could be two interfaces on one 5G network, fulfilling the vision of a unified communications fabric.

Conclusion

NRoC (Next-Gen Radio over Coax) represents a bold convergence of cable and wireless engineering – it seeks to turn the extensive HFC cable plant into a backbone for 5G networks. Architecturally, NRoC overlays 5G NR signals on existing coaxial infrastructure (HFC), using Distributed Access Architecture nodes as injection points and new TDD-capable amplifiers and CPE to extend 5G’s reach directly to homes  . This approach converges the traditionally separate DOCSIS and mobile worlds into a single platform, allowing fixed and mobile services to be delivered over the “same infrastructure” .

Compared to legacy DOCSIS, NRoC offers massive new spectrum and dynamic capacity, leveraging 5G’s advanced PHY/MAC to boost throughput and responsiveness on coax  . Versus standalone 5G, NRoC offers a shortcut to densification – cable nodes become ready-made small cells with built-in backhaul and power, saving cost and time  . Use cases range from ultra-fast residential broadband (10G services, low-latency gaming) to mobile xHaul (cheaply backhauling 5G sites or extending coverage) to private 5G networks in enterprises and venues using existing cable wiring  . Early field applications target offloading mobile traffic (e.g. Charter’s CBRS microcells) and adding capacity in high-demand areas without pulling new fiber  .

Realizing this vision comes with challenges: the cable plant must be overhauled to handle 3–5 GHz TDD signals, requiring innovative amplifier design and careful RF planning . Precise synchronization and scheduling are needed to marry 5G’s TDD frame with the shared coax medium, and QoS coordination is essential to maintain service fairness. Integration with a 5G core network, while optional at first, is a key step to unlock full convergence – enabling seamless service continuity between coax and cellular connectivity  . The effort is non-trivial, but the industry’s progress is evident: feasibility has been demonstrated, and vendors are building NRoC-capable nodes and CPE .

The vendor ecosystem is coalescing with both established players (cable equipment vendors adding support for NRoC, chipmakers considering extended spectrum) and new entrants (startups like Air5 focusing purely on DOCSIS-5G fusion)  . CableLabs and SCTE are poised to codify the needed standards, drawing on both DOCSIS evolution and 3GPP’s convergence frameworks. Importantly, 3GPP has already laid groundwork for integrating cable access into 5G systems via WWC (Wireless-Wireline Convergence) , signaling that the broader telecom community sees value in unifying access technologies.

In the big picture, NRoC can be viewed as a stepping stone toward the future of converged networks. It blurs the line between “wired” and “wireless” – using a wired medium to carry a wireless format – and in doing so, maximizes the utility of the cable network while bringing the benefits of 5G to more places. As 5G Advanced and eventually 6G standards are developed, the lessons from NRoC could inform more integrated designs that treat fiber, coax, and wireless holistically. Cable operators, meanwhile, gain a strategy to remain competitive in both fixed broadband and mobile arenas, potentially offering a truly seamless connectivity experience to customers.

NRoC is still in early days, but it carries a lot of momentum. In the next couple of years, keep an eye on CableLabs and operator announcements of field trials and the first commercial NRoC deployments (perhaps in a high-traffic city zone or an enterprise campus). Success of those trials could lead to NRoC becoming an official CableLabs spec and a deployable technology by the later 2020s . If that happens, the converged network dream – where your home’s broadband and your mobile phone and even IoT devices all share a common 5G-based infrastructure – will be a significant step closer to reality, delivered over the very same coax cable that once only carried television.

Sources:

• Baumgartner, J. “Cable’s secretive ‘NRoC’ project explores way to run 5G on HFC.” Light Reading (May 20, 2024)      .

• Dawson, D. “New Radio over Coax.” POTs and PANs (May 8, 2025)   .

• Benton Institute, “New Radio over Coax” (analysis summary, May 2025)  .

• Light Reading, “Vecima puts ‘New Radio over Coax’ in sight with 4GHz-capable node.” (June 6, 2025)   .

• Light Reading, “Cable operators see surge in network upgrade options.” (Oct 2023)  .

• Light Reading, “Startup Air5 aims to fuse DOCSIS with 5G.” (Sep 2025)   .

• CableLabs blog, “Driving 5G and HFC Convergence with Multi-Tenancy at the Edge.” (May 5, 2022) .

• CableLabs, “CableLabs 5G Challenge White Paper – Best Practices for Deploying 5G in a Shared Environment.” (2022) .

• CableLabs Insights, “Cable: 5G Wireless Enabler.” (Winter 2017)  .

• CableLabs blog, “The 6G Network Is On the Horizon.” (Jan 25, 2024) .