In the cable access market, the traditional cable TV service is shrinking, while the broadband service becomes a new growing point. Following this trend, MSOs are intend to provide higher bandwidth service and build a converged full service access network. To meet this requirement, Huawei proposed the converged broadband cable solution, which integrates FTTx and distributed CCAP (D-CCAP), to help MSOs build ultra-broadband and converged service access network.

As global networks move towards ultra-broadband ubiquity, people are demanding a better bandwidth experience at all times and in all locations. To meet these requirements, efforts are not only made by telecommunications carriers to upgrade existing networks and deploy new technologies, but also by MSOs to seize new broadband development opportunities to speed up networks and increase bandwidth. Major measures taken by MSOs to increase bandwidth include accelerating the node-segmentation process, introducing DOCSIS 3.1 technology, and implementing hybrid fiber coaxial (HFC) networks. Using a distributed architecture, MSOs can improve the deployment efficiency of these measures and save investment at the same time.

Huawei D-CCAP (Distributed-CCAP) solution is based on distributed access architecture. By this solution, optical line terminals (OLTs) are deployed in the headend room and CCAP devices formerly deployed in the headend are transferred to optical nodes.

This solution has the following advantages over the traditional CCAP solution:

Save 30% investment, 70% headend space and 80% fiber resource

Compared to distributed architecture, traditional node-segmentation requires more equipment, including deploying CMTS and CCAP plug-in frames, boards, and optical transmitters and receivers at the headend, and connecting even more optical fibers to new optical nodes. Therefore, traditional solutions need more headend space, larger power supplies, and additional optical fibers. Whereas in a distributed solution, only a few optical line terminals (OLTs) need to be deployed at the headend, fibers can be reused through digital fibers, and DOCSIS-compatible coaxial media converters (CMCs) are deployed without adding optical transmitters and receivers. This simplified solution can reduce headend space usage by 70%, power consumption by 50% and fiber resource usage by 80%. The D-CCAP solution can also be applied in demand-based speed acceleration scenarios in high-bandwidth areas, reducing both investment and deployment time while continuing to support the existing CMTS network.

Increase DOCSIS3.1 bandwidth by 30%

In a few years, DOCSIS 3.1 technology will be gradually introduced to the CCAP network to facilitate the deployment of new modulation technologies to increase bandwidth. How can DOCSIS 3.1 be deployed to fully leverage bandwidth potential? To achieve this, higher-order modulation methods must be adopted, such as, 1024QAM or higher-order ones, which require a higher Carrier noise ratio (CNR) of lines. However, the analog fiber modulation and transmission mode used in traditional CMTS often reduce CNR, making it impossible to adopt higher-order modulation methods. In comparison, an attenuation of 6 to 9 dB for CNR can be achieved in D-CCAP through digital fibers and transmission technology, paving the way for higher-order modulation methods. For example, in a distributed architecture, the bandwidth for each channel of DOCSIS3.1 can be increased from 1382M@256QAM to 1900M@2048QAM. Empirical research data shows that D-CCAP can increase the average bandwidth by 30%.

One platform for FTTx and DOCSIS

When deploying CCAP networks with access over coaxial cables, MSOs often apply FTTP methods for newly constructed areas and commercial users, such as, passive optical network (PON), RFoverlay, DPoE/DPoG, and RFoG. PON technology, with a mature industrial chain and robust bandwidth expansion capabilities, is the standard method for future FTTx. A distributed network can converge with PON where both PON and DOCSIS can be deployed on one access platform without changing the O&M process of the DOCSIS system. Therefore distributed networks have become the primary choice for carriers implementing network convergence.

With high deployment efficiency, huge bandwidth potential, and compatibility with other technologies and networks, distributed networks have become a strongly favored solution for MSOs. Since its release in 2012, the D-CCAP solution has been put into large scale commercial use in China, Russia, Europe, Latin America, and the Asia-Pacific region.