EPON EoC solution for the next generation cable TV broadcast network
The traditional cable network only supports unidirectional downlink broadcast services. To improve the ARPU value of users, operators urgently need to transform the hybrid fiber coaxial network (HFC) to provide two-way, interactive services. In the next-generation broadcast network (NGB), the next-generation broadcast network architecture based on EPON + EoC provides a simple end-to-end Ethernet-based packet network that can operate together with the existing cable TV network ...
The traditional cable network only supports unidirectional downlink broadcast services. To improve the ARPU value of users, operators urgently need to transform the hybrid fiber coaxial network (HFC) to provide two-way, interactive services. In the next-generation broadcast network (NGB), the next-generation broadcast network architecture based on EPON + EoC provides a simple end-to-end Ethernet-based packet network that can operate together with the existing cable TV network, as shown in Figure 1. Show.
Figure 1: Next-generation broadcast network architecture
In Figure 1, the EoC central office equipment includes a coaxial cable broadband access terminal (CBAT) and a cable TV signal mixer, which can provide bridge and management functions for the EoC network to realize two-way services of broadcast TV, such as: IPTV, VOD, HSD, VoIP and P2P games, etc. This article introduces the overall background of EPON and EoC technology, and discusses in depth the EPON EoC solution that can be used for two-way transformation of cable TV networks.
EPON, EoC technical characteristics
EPON: EPON technology can provide bidirectional 1Gbs link connection with a downstream wavelength of 1490nm and an upstream wavelength of 1310nm. The downstream data stream is transmitted to all ONUs (optical network units), and the LLID field is added to the preamble (logical link ID) to distinguish the destination of specific frames in the PON network; in the upstream data, the DBA is responsible for the registered ONU Dynamically allocate bandwidth. The advantages of EPON system are as follows:
â—Ž Easy to integrate and simple and practical-EPON is based on Ethernet technology, which can mix and propagate VoIP, IPTV, data and various RF data streams on the same architecture, while providing QoS mechanism to ensure the transmission quality of different data streams.
â—Ž Long distance-When the EPON network adopts forward error correction (FEC), it can be extended to 20 kilometers or even 30 kilometers. The loss caused by the fiber optic architecture is only 1dB per 2000 feet.
â—Ž Low cost-Due to the use of passive splitter, the cost of operation and maintenance will be lower than that of coaxial cable in the long run.
◎ High reliability—As a passive network that does not include any power-consuming electronic components, it has higher reliability.
EoC: Ethernet coaxial network (EoC) refers to the use of coaxial cable to transmit Ethernet signals between two or more points. Mainly include: baseband (passive system) or radio frequency modulation (active system) two transmission methods. The baseband system is easy to set up and use. The disadvantage is that it requires a point-to-point connection to obtain a data rate (> 10Mbps) suitable for the current application requirements of the IP network; the active system can support multiple client devices connected to the same coaxial cable, and all clients Both can be controlled by a central master located at the node. Currently, there are two types of active systems: systems based on the Coaxial Multimedia Alliance (MoCA) industry standard and systems based on the Home Telephone Line Network Alliance (HPNA) standard. The main difference between MoCA and HPNA is the frequency range they use: MoCA is used in the frequency range higher than 862MHz for local building distribution, and in the latest version 3.1, HPNA uses the frequency range of 4 ~ 52MHz.
EPON + EoC solution
In the domestic cable TV next-generation broadcast network, the EoC central office master device plays a key role-bridging fiber and 2 coaxial cables, and managing the authorization and transmission of client devices in the EoC network. The EoC master device can be divided into two types according to whether or not the ONU is integrated. as shown in picture 2:
Figure 2: EoC central office equipment type
In Type A, similar to the ONU currently deployed by telecommunications companies, its ONU is independent of the EoC's central office master device. The EoC master device consists of a silicon chip (HPNA Master, MoCA network controller device or HomePlug) that controls the CPU, EoC central office technology, and a mixer that can superimpose the cable TV signal on the output coaxial cable. When using this mode, PMC's MSP7150 is an ideal solution that can be used as the main control to control the CPU and PCI bus. In addition, in certain areas, EoC main device equipment needs to provide some functions of the third layer gateway, such as routing, NAT and firewall, etc., and the hardware and software platform of MSP7150 can fully support these functions.
In Type B, the ONU is integrated into the EoC master device. This solution greatly reduces the equipment and maintenance costs of cable operators. When using this technology, if the gateway function is not required, the CPU embedded in PMC PAS6301 can be used for the control CPU of the EoC network; otherwise, the system needs to add MSP7150 as the control CPU and provide the corresponding gateway function.
With mature EPON technology, high throughput and flexible software architecture, PMC's EPON EoC solution can accelerate the transitional development of cable TV networks. Figure 3 is a typical B-type device, which uses PMC's ONU, CPU solution and EoC central office master device products of third-party partners.
Figure 3: EPON EoC reference design
The design scheme in Figure 3 can support a throughput of more than 400Mbps, multiple EoC master node and the required network data processing functions, including VLAN, QinQ, PPPoE, DHCP, QoS, WebGUI and SNMP, in addition, it can also support Enhanced service functions including routing, firewall, NAT, Wi-Fi, and VoIP, and has rich expansion space to accommodate future applications.
Detailed EoC technology
The following briefly introduces the two EoC technologies of HPNA and MoCA based on the PMC scheme, which are currently used in the system. Other EoC solutions such as HomePlug are also more common.
HPNA: HomePNA technology can provide QoS bandwidth guarantee, remote management and diagnostic capabilities, and a physical data transmission rate of up to 320Mbps, its system central office master not only serves as a coaxial cable network and a connection gateway based on IP and Ethernet PON networks, And can manage all client devices. In a system based on HPNA 3.1 version, the host can support and control up to 32 client devices connected to a coaxial cable through any tree or star architecture. The typical HPNA architecture is shown in Figure 4.
Four operating modes are defined in the HPNA 3.1 version. These four modes occupy different spectrums, and different networks can choose to use their optimal operating mode.
Table 1: HPNA3.1 version operating mode
According to different frequency allocations, the physical data rate can reach up to 320Mbps, which can achieve dynamic allocation among up to 32 client devices in half-duplex mode. (For example, in the half-duplex mode, the HPNA system uses the same frequency range to transmit and receive to the client device).
The HPNA MAC layer protocol is responsible for managing client devices and at the same time ensuring the maximum bandwidth of each client device. In addition to managing client device management, the HPNA MAC layer also supports all functions required to manage QoS bandwidth guarantee and optimization, so that HPNA can be applied to VoIP or similar multimedia applications that require guaranteed transmission bandwidth.
MoCA: MoCA version 1.1 enables MoCA to achieve 175Mbps MAC layer data throughput at a physical data rate of 270Mbps. The performance improvement is mainly achieved by integrating multiple Ethernet packets into a single MoCA frame. The latest MoCA 2.0 will be used by The idle frequency band, which is higher than the cable TV service, further improves the data transmission rate, so that it becomes the EoC technology with the highest data transmission rate again. The MoCA network architecture is shown in Figure 5.
Figure 5: MoCA network architecture
In the MoCA network, the central network controller node is responsible for the authentication of the MoCA client device, controls the transmission of data in the terminal and manages the key through the MAP information. MoCA 1.1 version introduces parameterized QoS to support bandwidth reservation and device access control.
In view of the current situation of regional division of domestic cable networks, the author believes that in the future of network access technology competition, the two EoC technologies will not have the ultimate winner. Not only that, various other technologies that enable the transmission of Ethernet frames in the home network will also be adopted, such as HomePlug AV and WiFi based on coaxial cables.
For cable operators, no matter which access technology they choose in the future, EPON EoC solutions based on PMC's PON chips and CPUs can meet their needs well.
At present, the domestic Chinese cable TV network is being upgraded from a traditional HFC broadcast network to a two-way, interactive, high-speed, all-IP based next-generation broadcast network. As a mature technology, EPON is very suitable for replacing the optical fiber part in the HFC network. After years of development, EoC technology can be fully deployed as a solution for the last 1 kilometer network connection. PMC's reference design can help potential system providers to develop EPON EoC solutions in a timely manner.
* PMC-Sierra is the industry's leading provider of network architecture semiconductor solutions, supporting both EPON (IEEE 802.3ah) and GPON (ITU-T G.984) standards, and the industry's first symmetric and asymmetric 10G EPON reference design platform. The PMC-Sierra system-on-chip solution is currently running in more than 8 million PON ONU devices worldwide.
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