HFC (Hybrid Fiber-Coaxial), or hybrid fiber coaxial cable network, is an economical and practical comprehensive broadband network access technology for digital services. Hybrid fiber/coaxial networks (HFC) evolved from traditional cable networks. Traditional cable networks are mostly coaxial cable systems or microwave cable systems, which can only transmit dozens of TV programs.
With the development of social economy and the increasing demand for information, traditional cable TV networks have been difficult to meet the demand.
In the early 90s of the 20th century, with the maturity and development of optical transmission technology, people began to consider the use of optical transmission in cable TV systems, and this cable TV network using optical transmission is Hybrid Fiber Coax (HFC), which has the advantages of frequency bandwidth and large capacity.
With the development of technology, HFC networks are often given new meanings, especially CATV networks that use hybrid fiber coaxial for broadband digital communication. Therefore, HFC networks that can operate various digital services in both directions are usually called HFC, while HFC that can only operate broadcasting services in one direction are called CATV.
HFC is usually composed of three parts: optical fiber trunk, coaxial cable branch and user wiring network, and the program signal from the cable TV station first becomes an optical signal and is transmitted on the trunk line; After reaching the user area, the optical signal is converted into an electrical signal, which is distributed by the distributor and sent to the user through a coaxial cable. The main difference between HFC and early CATV coaxial cable networks is that optical signals are transmitted with optical fibers on the trunk line, and the point power-optical conversion needs to be completed in the front section, and the optical-electric conversion must be completed after entering the user area.
The various services that the HFC network can carry:
-Analog and digital television transmission business
- Cable broadcasting business
-INTERNET data access services
- Data interaction applications
- IP telephony services
-Video on demand business
HFC main features:
1. Large transmission capacity, easy to achieve two-way transmission, theoretically, a pair of optical fibers can transmit 1.5 million telephones or 2,000 sets of TV programs at the same time
2. Good frequency characteristics, no need to equalize in the cable TV transmission bandwidth
3. The transmission loss is small, which can extend the transmission distance of cable TV, and there is no need for relay amplification within 25 kilometers
4. There will be no crosstalk between optical fibers, which is not afraid of electromagnetic interference and can ensure the transmission quality of the signal.
5. Compared with the traditional CATV network, its network topology is also somewhat different: first, the optical fiber trunk adopts a star or ring structure; second, the coaxial cable part of the branch and wiring network adopts a tree or bus structure; Third, the entire network is divided into a service area according to the optical nodes; This network structure can meet the requirements of providing users with a variety of business services.
The global direction of hybrid fiber coaxial cable (HFC) networks:
1. Europe Liberty Global upgraded its HFC network with CommScope's vCMTS technology to achieve 1.8GHz spectrum expansion with downlink speeds of up to 8 Gbit/s. Mediacom plans to increase uplink bandwidth through DOCSIS 3.1 upgrades and spectrum segmentation, and gradually transition to DOCSIS 4.0, aiming to achieve 10Gbps network speeds. Harmonic set a record download speed of 14 Gbps in interoperability tests, validating the technical potential of HFC networks.
2. Huawei's D-CCAP solution optimizes the HFC architecture through PON technology, reducing the use of analog devices, saving space and energy consumption in the data center, and supporting smooth FTTH evolution. Hefei Cable uses Huawei's OTN solution to build a full fiber optic network with "gigabit interaction and 10000 gigabit broadcasting" to support 4K/8K video and smart city services.
3. Companies like Charter, Rogers, and others are exploring Next-Gen Radio over Coax (NRoC) technology to transmit 5G signals over HFC networks, expanding network capacity to the frequency band beyond 4GHz.
4. Developed countries such as North America and Europe are focusing on promoting DOCSIS 4.0 upgrades, such as CableLabs in the United States, which achieved a downlink rate of 14Gbps to verify the feasibility of HFC competition with fiber optics.
Developing countries such as China are gradually improving urban and rural network coverage through HFC network optimization and fiber into the home.
