Wideband access system based on HFC (Hybrid Fiber Coaxial) network

Abstract

The invention discloses a wideband access system based on an HFC (Hybrid Fiber Coaxial) network, comprising a front-end access system, the HFC network and a terminal access system. The wideband access system is characterized in that the front-end system is provided with a cable forwarder modem termination system (CFMTS) and a channel dispatch controller (CDC); the terminal access system is provided with a cable forwarder modem (CFM) and a transmission multimedia to a user terminal, wherein the CFMTS is connected with an IP (Internet Protocol) backbone network; a mixer, an optical transmitter,a photoelectric converting node, an upper frequency converter, an optical receiver and an uplink allocator are arranged between the CFMTS and the CMF. By improving a network structure, network equipment and the network wideband allocation of the traditional structure, the wideband of an uplink channel is enlarged, the uplink noise brought by an access cable can be blocked off and the transmissioncapability of the network can be enhanced. The wideband access system provides the function of multiplexing and de-multiplexing video streams of the uplink channel and the downlink channel, ensures the mixed transmission of uplink data, voice and video and meets the requirement of three-network integration while the traditional simulation television, an edge quadrature amplitude modulator (EQAM),a set top box and other equipment are ensured to normally work.

Description

technical field [0001] The invention relates to broadband network access technology, in particular, a broadband access system based on HFC network. Background technique [0002] At present, the broadband access network based on the HFC (Hybrid Fiber Coaxial) network adopts the DOCSIS (Data-Over-Cable Service Interface Specifications) standard, which is a technology proposed by the United States and accepted by the International Telecommunication Union. standard. Europe proposed the EUR-DOCSIS standard on the basis of DOCSIS, that is, the European DOCSIS standard, and China proposed the "HFC Cable TV Data Transmission System" standard with reference to the EUR-DOCSIS V1.1 standard. Although these three technical standards are in the physical layer Bandwidth, QAM (Quadrature Amplitude Modulation, Quadrature Amplitude Modulation, Quadrature Amplitude Modulation) modulation constellation and the frequency range used by the reverse channel are somewhat different, but they are ba...

AI Technical Summary

Problems solved by technology

[0006] ①The coaxial cable network is a tree structure, and there is serious funnel noise in the reverse channel, so that the uplink signal can only be modulated by 16QAM and QPSK (Quadrature Phase Shift Keying, Quadrature Phase Shift Keying) with strong anti-interference ability format, it is difficult to use 64QAM or 256QAM with high frequency band utilization efficiency

Moreover, the uplink bandwidth is too narrow, so it is difficult to guarantee the needs of future services

[0007] ②The standard before DOCSIS 3.0 has no channel bonding technology, and multiple users share one downlink and one uplink channel. For 64QAM modulation, the maximum rate of a downlink channel is 41.712Mb / s, and it is impossible to provide an interface rate of 100 Mb / s

DOCSIS 3.0 uses channel bonding technology, which can provide high-speed interfaces, but requires multiple CMTS and multiple CMs, and users need multiple CMs, and the cost is high

[0008] ③ Although the transmission equipment CMTS and CM of this network can mix and transmit downlink data and video streams, they only process data information, and do not process issues such as multiplexing / demultiplexing of video signals, and cannot transmit at the same time multiple single program streams

[0009] ④ Multiple users of this network share an uplink channel and work in TDMA or CDMA mode. When TDMA is used, the users must first synchronize with the clock of the cable modem head-end system, and need to continuously measure distance , bandwidth allocation, clock synchronization, etc., not only the operation is complicated, but also the extra overhead is large, so that the utilization efficiency of the available bandwidth is low

[0010] ⑤ Due to the complexity of the DOCSIS protocol, both CMTS and CM must perform complex protocol processing, the equipment is relatively expensive, and the network construction cost is relatively high to provide broadband transmission capabilities

[0012] ⑦The uplink channel of DOCSIS cannot use the convergence sublayer, which is not suitable for the mixed transmission of data and video stream signals

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