KR20040045952A - High speed subscriber access network technology for the age of converging broadcasting and communication technologies - Google Patents

Abstract

PURPOSE: A very high speed subscriber network technique for broadcasting communication convergence service is provided to minimize investment cost for building a very high speed subscriber network and facilitate application to an existing building. CONSTITUTION: In order to build a very high speed subscriber network, a 6MHz bandwidth channel is modulated through a QAM(Quadrature Amplitude Modulation) method and a plurality of QAM modules are processed in parallel to increase a transmission speed. An MAC layer adopts a 802.3 ethernet MAC type, so existing hardware and software techniques can be utilized as it is. IEEE 802.3z GMAC(Gigabit ethernet MAC) and parts modulated and demodulated through the QAM method follow a GMII(Gigabit Media Independent Interface) standard interface. A modulated signal is transmitted to a cable network and the signal received from the cable network is demodulated, and then transmitted to a GMAC terminal. A transmitter and receiver can be implemented by two semiconductors or can be integrated to one semiconductor.

Description

High speed subscriber access network technology for the age of converging broadcasting and communication technologies

The convergence of broadcasting and communication has enabled a variety of new services that were not available in the past, such as multimedia high-speed Internet, VOD, and Internet broadcasting. One of the problems to solve in order for these new services to be universally spread is to greatly speed up the subscriber network. Currently, many popular subscriber network technologies, xDSL and cable modem, have technical limitations to provide new types of services. Ultimately, the application of FTTH technology can solve the problem, but it requires a large-scale new investment in the construction of the optical cable infrastructure, and it is not easy to install in the existing building rather than the new construction work.

The present invention is a technique for minimizing new investment costs and easily applying to an existing building for establishing a high-speed subscriber network for broadcasting communication convergence service, and is a technique for solving the problems of the prior art.

Figure 1 shows a simplified diagram of the connection between the CATS (center equipment) applying the EtherModem technology and a plurality of subscriber station CAE.

2 shows a method of creating channels in units of 6Mhz, separating these channels into upper and lower Txs and Rxs, and allocating 10 channels to implement 1Gbps transmission rates.

FIG. 3 is a connection diagram applying CATS and CAS interconnections to a general house and apartment with a product using EtherModem technology.

4 is a block diagram when implementing a TX PHY ASIC to which EtherModem technology is applied.

5 is a block diagram when implementing the RX PHY ASIC to which EtherModem technology is applied.

CATV coaxial cable, which is widely used at present, has a cable network that supports 450Mhz bandwidth, but most of it will be replaced with a cable network that supports 750Mhz or more. In order to transmit analog TV signals, such a cable network is currently used by allocating a frequency range for each channel. Cable modems are used for data transmission by utilizing frequency ranges not used in cable TV. The data rates of cable modems are up to 10Mbps and down to 40Mbps. By applying QAM technology, Cable Modem has an effective distance of 16Km to 24Km and a data rate of up to 40Mbps using 8bit, 256QAM, and 5M symbol rates for one 6Mhz channel bandwidth.

Cable Modem adopts highly precise Forward Error Correction technology (Reed Solomon coding or Trellis Coding), taking into account the noisy network characteristics by sharing the line with CATV image signal.

If 1) shorten the effective distance between the center equipment CMTS and subscriber equipment Cable Modem, 2) improve the characteristics of the cable network by limiting the number of subscribers connected to one cable jointly, and 3) channel for data transmission. By multiplying the data in parallel to transmit data in parallel, the data transfer rate can be greatly improved.

That is, data is transmitted at 100Mbps per 6Mhz channel using 1024 QAM and 10M Symbol / s as the basic technology. In parallel, 10 channels are used to achieve a transmission rate of 1 Gbps. Theoretically, when 750Mhz coaxial cable is used for digital transmission, the number of 6Mhz channels can be 120 and up to 100Mbps for each channel, so the transmission speed can be up to 12Gbps. The technology applying the above basic principle is EtherModem technology.

Conceptually, it is a new technology using IEEE802.3z Gigabit Ethernet MAC Layer as the Data Link layer in the OSI 7 Layer structure and Quadrature Amplitude Modulation as the core technology in the Physical layer. It is a technology for providing integrated broadcasting and telecommunication information to a home via cable.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, CATS (Cable Access Termination System) and CAE (Cable Access Equipment) are equipments using EtherModem technology. CATS, which is connected to the backbone network via optical cable, is connected to CAE equipment located in each home through coaxial cable.

That is, CATS has a function similar to the existing Cable Modem Termination System (CMTS) or Digital Subscriber Line Access Multiplexer ( DSLAM), and CAE has a function similar to Cable Modem (CM) or ADSL Modem.

FIG. 2 illustrates, for example, a frequency band to be allocated when implementing EtherModem having a transmission rate of 1Gbps. In the figure, it is assumed that 6Mhz channels are represented by one line in the Tx and Rx frequency bands, and 10 are allocated to each. By using 1024 QAM and symbol rate per unit channel as 10M Symbol / s as the basic technology, the transmission speed is 100Mbps per channel. Video Downstream can be an analog TV signal or a digital TV signal. The transmission and reception bands do not necessarily need to be separated as shown in FIG. 2, and both bands can be allocated according to the higher frequency.

In order to construct a high-speed subscriber network suitable for broadcasting communication convergence service using coaxial cable, 6Mhz bandwidth channel is modulated by QAM method, and multiple QAM modules are processed in parallel to increase transmission speed. At the MAC layer, the 802.3 Ethernet MAC specification can be used to leverage existing hardware and software technologies.

Modulation and demodulation using the IEEE 802.3z Gigabit Ethernet MAC (GMAC) and Quadrature Amplitude Modulation (QAM) methods follow the GMII standard interface standard. The modulated signal is transmitted to the cable network, and the signal received from the cable network is demodulated and transferred to the GMAC stage through the GMII interface.

The transmitter and receiver may be implemented separately from two semiconductors, or may be composed of one semiconductor incorporating two functions. Basically, transmitter and receiver

4 and 5 show the block diagram structure in ASIC. In each figure, the interface with the upper MAC is exemplified by GMII, but in fact, it can be any form of Media Independent Interface.

Next, each specific function will be described with reference to the block diagrams of FIGS. 4 and 5.

EtherModem TX PHY Function

Among the major components, Gigabit Media Independent Interface (GMII) Tx implements the signaling protocol for receiving data from GMAC and sends data to the Transmission Framer stage at 125Mhz in 8bit units in compliance with the rules defined in IEEE802.3z. Framer reconstructs data received in 8-bit units in 100-bit units, processes them in the Screambler stage, and transmits them in 50-bit units to the FEC stage. FEC block is composed of two blocks to increase the density of ASIC. The FEC block is RS Encoder of Block Encoding method and processes data in 50 bit unit and transfers to Interleaver. Interleaver can reduce the burst noise error by one million units by distributing the burst error into multiple RS codewords. In the final stage of the FEC block, Trellis Encoder is used to minimize the influence of channel noise. The 10 QAM modulators in the final stage are processed in 100 bits in parallel. It transmits to each DAC stage.

EtherModem Rx PHY Features

Signals received from the ADC are processed in 10 QAM demodulators in 10 channels, respectively, and deliver 5 QAM demodulators to two FEC stages.

The FEC stage performs Trellis Decoder, deinterleaving, and RS decoding, and simultaneously transmits 100 bits from each of the two FECs to the next frame, the Reception Framer, and transmits data at 125Mhz in 8-bit units to GMAC according to the GMII signal.

Thus far, the present invention has been described in connection with specific examples.

1) By utilizing existing CATV coaxial cable connected to the general home, large-scale investment is unnecessary for new network facilities as in the case of optical cable networks.

2) It provides a large data transmission speed to the general home, and provides an integrated broadcast communication network that can be used not only with the current analog broadcasting but also with the digital broadcasting in the future.

3) The terminal devices share a single coaxial cable, which is realized as a simple network.

4) From the point of view of the communication layer, the MAC layer of this technology uses Ethernet MAC technology, which is now commonly used, to guarantee the continuity of existing equipment investment by using existing hardware and software products as they are.

Claims (6)

As a subscriber network technology, the MAC layer applies the MAC technology defined in IEEE802.3 Ethernet and the QAM type modulation technology is applied to the physical layer according to the communication standard. Method of increasing the data transmission rate per unit time by simultaneously arranging QAM modulators in parallel and assigning specific frequency bands to each modulator at the same time The method of claim 1, wherein the interface between the MAC layer and the physical layer QAM modulator is connected using the Gigabit Ethernet Media Independent Interface (GMII) standard used in Gigabit Ethernet, or the MII standard defined at 100 Mbps. Integrated network system for broadcasting communication that enables bidirectional transmission for communication packet in the same transmission network and transmits broadcast signal only in a single direction of subscriber side. A method of reducing the size of a chip in an ASIC implementation by sharing a FEC block located in front of a QAM modulator in claim 1 with a plurality of QAM modulators The method of claim 1, wherein a plurality of FECs share a framer / scrambler block located in front of the FEC.