FI119313B - Broadband data transmission in a cable TV network - Google Patents

Description

119313

Broadband data transmission over cable television network

Field of the Invention

The invention relates to an arrangement for transmitting a broadband data signal in a cable television network.

Background of the Invention

The increasing use of the Internet and the transformation of various services to IP-based (Internet Protocol) are constantly increasing the demand for broadband data connections. The broadband subscriptions currently available are typically either xDSL or cable modem subscriptions. Especially in the 10 areas where the television signal is brought to households via a cable network, the cable network also provides a ready-made transmission path for the transmission of data signals.

In a DOCSIS (Data-Over-Cable Service Interface Specifica-15 tions) cable television system (CATV), the data signal is modulated to its own frequency (channel) like TV signals, whereby the signals can be transmitted on the same cable and separated at the receiver. For households ... the disadvantage is that a special additional cost cable modem (CM) 20 is needed to modulate / demodulate the signals - * ··; to establish a data connection to the computer. The problem for my cable network; * operators is that the cable modem:: expensive CMTS (Cable Modem)

Termination System) can only provide a limited number of connections. The CMTS controls all cable modems connected to the cable network within its domain, which requires the CMTS to maintain a register of active cable modems and distribute the available · ·. · **; a transmission band between all cable modems. Again, this requires that each cable modem should be allocated sufficient time to · ·: "30 submit upstream channel requests and range parameters. If the user needs more bandwidth in upst:; *; ream direction. , through the cable modem CM, a request may be made to the CMTS to request a higher bandwidth alloy 119313 2, but this will always cause a significant delay before a higher bandwidth is available.

In addition, in DOCSIS, channel allocation between downstream and upst-5 ream channels is typically strongly asymmetric, thus making the upstream bandwidth provided by the system easily insufficient for new two-way IP-based services such as VoIP and peer-to-peer applications, at the same time as other data services. Providing a higher bandwidth of 10 upstream directions will in most cases require the construction or upgrade of an expensive fiber optic network arrangement for the reverse channel. All in all, the DOCSIS-based CMTS centralized data network is cumbersome to manage and quite inflexible in terms of capacity expansion. One of the 15 CMTS manages thousands of household subscriptions, which share the available data transfer capacity in both frequency and time division. When the capacity of an existing CMTS runs out, a new CMTS is needed for new users, which is typically under-utilized, at least initially.

20

A further problem is that the "last 100 meters",; j 'of CATV networks are implemented with various network topologies, such as coaxially cabled *: * star or tree or cascade networks. Buildings may: also include a complete local area network or local area network ···:. *. 25, such as Cat1 or Cat5, whereby it would be advantageous to be able to utilize this existing cabling.

· · ('"A In each of these network topologies and end-to-end LANs, data connections must be organized differently.

* * 30 Applicant's earlier patent application Fl 20045502 (also EP 1675288) describes an arrangement for transmitting a baseband Ethernet signal in a bidirectional cable connection together with a CATV signal. with. Since transmission of the baseband data signal does not require * · * modulation / demodulation, passive components may be used to combine and separate the CATV signal and the baseband Ethernet signal. However, this application focuses specifically on the so called '' To the last 100 meters '', i.e. the CATV network arrangement, in the essential proximity of the household connections 119313 3 from the distribution point (EMT, Ethernet multitap) as a coaxial cable network to the household access point. However, the application does not further elaborate on the introduction of a broadband Ethernet data signal to the Ethernet switch EMT.

5 In view of these problems, it is clear that there is a need for a network arrangement that allows more flexible and efficient data connection management in a general manner, while respecting the constraints of different network topologies for organizing data connections.

Brief Description of the Invention

An improved arrangement has now been developed to reduce the above problems. Various aspects of the invention are provided by a communication system, a modulation unit and a demodulation unit, characterized by what is stated in the independent claims. Preferred embodiments of the invention are claimed in the dependent claims.

The invention is based on providing a communication system for transmitting a data signal over a cable television signal in an adapted coaxial cable network, the communication system comprising a ··· coaxial cable connection for distributing a cable TV signal to a cable television network distribution point. The communication system further comprises "! ·. A first data network switching point for baseband broadband ·" ·. for supplying a data signal to said telecommunication system; A '25 modulation unit for generating a modulated data signal from said baseband broadband data signal, which is a modulated »· * ··· * data signal comprising at least two signal components logically connected but modulated to different communication channels; a connector fitted to said coaxial cable to adapt said modulated data signal to its own frequency channel for transmission on said coaxial cable; a separator adapted for said coaxial cable connection to separate said modulated data signal into a separate signal; a demodulation unit for demodulating and combining said signal components into a baseband * "·: 35 wideband data signal; and a second data network switching point 119313 for forwarding a baseband wideband data signal to at least one node of the data processing device.

In other words, one of the starting points of the invention is that by establishing a communication system as described above, a CATV network portion based on a coaxial cable can advantageously provide a transmission path for an Ethemet data signal which is separable and manageable by available network topology and cabling. . The modulated Ethernet signals are fed into a coaxial cable instead of an optical fiber, which thus forms a kind of "virtual" optical fiber for system operation.

As essential aspects of Ethernet signal modulation, a modulation unit adaptable to a coaxial cable network, comprising an input for supplying a baseband broadband data signal to said modulation unit, is also disclosed; separating means for dividing a baseband broadband data signal into at least two separate signal components, modulating means for modulating said signal components into different data transmission channels; and a control unit for controlling said separator means and modulation means so that said signal components can be logically combined into a single data signal, and a coaxial: * · cable adaptable demodulation unit comprising * 1 «: at least two inputs of at least two modulated * *! "·! To supply a signal component to said demodulation unit, said signal components being logically combinable into a single data signal; demodulation means for demodulating said signal component to baseband data components; - · * · .. for controlling the warping and combining means to combine said. ···. Signal components into a single data signal.

• · ·: .. v 35 Such modulation / demodulation units allow at least 100

Mbps or even higher data rate Ethernet-119313 5 signal transmission over a coaxial cable network without the receiving node having to include a cable modem.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further described in connection with preferred embodiments, with reference to the accompanying drawings, in which:

Figure 1 is a simplified block diagram of a network arrangement according to the invention; Figure 2a shows a preferred embodiment of a network modem according to the invention in a simplified block diagram;

Figure 2b shows a preferred embodiment of a terminal modem according to the invention in a simplified block diagram;

Fig. 3 is a block diagram illustrating an embodiment for applying a network arrangement according to the invention 15;

Fig. 4 is a block diagram showing another embodiment for applying a network arrangement according to the invention; and Figure 5 is a block diagram illustrating a third embodiment for applying a network arrangement according to the invention; and FIG. 6 is a block diagram illustrating a fourth embodiment of a network arrangement according to the invention.

** ·· • * * * ···:.: V Detailed Description of the Invention * ·! ·· β! Figure 1 illustrates a network arrangement according to the invention by means of a simplified block diagram. The network arrangement comprises a fiber optic network ··· end node 100 serving as a television signal generator.

The node 100 is fed as input to the CATV network's main: V: optical cable TV signal from the optical fiber · ***: (CATV), which is converted at the node 100 into an electrical signal, ··· 30 modulated to the desired frequency and further divided into multiple coils. Further, the network arrangement comprises an Ethernet splitter 102, which is provided with an input of a very wide bandwidth, preferably ·: ··· Ethernet signal (GbE) transmitted over either a pair: cable or fiber connection. The Ethernet 35 branch splitter 102 splits the signal into a plurality of narrowband Ethernet signals, e.g., 100 or 200 Mbps. Each shared signal (e.g., 100 Mbps) comprises data that is dynamically assigned to specific Ethernet MAC destination addresses. In this way, each 100 Mbps Ethernet signal can be transmitted on its own channel to a common distribution point for home-5 economic connections, such as a home switchboard.

Each split signal branch of Ethernet splitter 102 is further coupled to modem 104 to modulate Ethernet signals before being fed into a coaxial cable. Ethernet signals are modulated by any one of 10 efficient modulation methods, such as 64-QAM modulation or 256-QAM modulation. Modulation can thus be performed, for example, in the same manner as in DOCSIS systems using a cable modem. Modulated Ethernet signals are fed into a coaxial cable, which now forms a virtual fiber for system operation. For combining Ethernet signals and CATV signals, the network arrangement comprises, for example, a connector 106 implemented by bandpass filters (if certain frequency bands are reserved for Ethernet signals). The modem 104 and connector 106 may advantageously be implemented as an integrated network device (dashed line) call an Ethernet network modem ENM.

tt; j · By using an 8 MHz channel bandwidth compatible with the channel bandwidth of the European · ··· PAL PAL TV standard, • t · ·. . ·. 256-QAM modulation achieves a data rate of about 50 Mbps per channel. Figure 2a illustrates a preferred embodiment of the Ethernet network modem ENM 200 in a simplified block diagram, wherein an incoming baseband 100 Mbps signal 202 is supplied to a separator circuit 204 which comprises means for dividing the signal into two 50 Mbps signal components. The isolation circuit may be implemented, for example, as a PLD (Prog- vv rammable Logic Device) circuit, such as an FPGA (Field Programmable Gate Array) circuit. From the isolator circuit, these signal components are applied to modulation units 206, 208 which match these two signal components! ···. preferably by 256-QAM modulation to two separate 8 MHz channels. The ENM further comprises a Media Access Control (MAC) unit 210, 35, which controls channel allocation and signal distribution to components based on Ethernet MAC addresses. Each of the two signal components is divided into data packets fed into its own channels having 119313 7 channels. bandwidth and modulation, and hence time delay, are substantially the same, which greatly facilitates synchronization and combining of the signal components at the receiving end.

Referring again to Figure 1, the coaxial cable assembly 108 comprises a required number of repeaters and amplifiers 110, the positioning and feature measurements of which are known to those skilled in the art and are not directly related to the implementation of the present invention. Before the distribution point 114 of the household connections (e.g., a house exchange), the separator 112 on the coaxial connection 10 separates the modulated Ethernet signals and the CATV signals, whereby the signals on the Ethernet channels (50 Mbps) are routed to the modem 116 for demodulation. Correspondingly, the CATV signals are typically routed to an amplified distribution point 114. In Figure 1, the separator 112 and modem 116 are shown as an integrated device (dashed line), which may be called an Ethernet terminal modem EAM.

Figure 2b shows a preferred embodiment of the Ethernet terminal modem EAM 220 in a simplified block diagram comprising the corresponding components as the ENM described above. Preferably, the EAM comprises two inputs for two 8 MHz channels comprising kaksi the two 50 Mbps signal components 222, 224 described above, which logically belong to a single 100 Mbps Ethernet signal. Each signal ·. The base component is demodulated in separate demodulation units 226, 25 228, and the baseband signal components thus formed are applied to a · · · "V combinator circuit 230 which bundles the signal components into a 100 Mbps baseband signal 232 for forwarding on the * MAC. Since each of the signal components is divided into data packets transmitted to the EAM advantageously: .v 30 in two channels with similar characteristics, the signal arrives the data packets to the EAM in the correct order for bundling, whereby the bundling of signal components in the receiving end Similarly, the combiner circuit may also be implemented, for example, as a PLD (Programmable Logic Device) circuit, such as 35 Field Programmable Gate Array (FPGA) circuits. The EAM also comprises a * "*: Media Access Control (MAC) 234, which together With ENM's MAC unit o controls channel allocation and signal component mapping based on Ethernet MAC addresses. MAC units control the sharing of a combined baseband 100 Mbps Ethernet signal dynamically according to the Ethernet protocol between the IP addresses of end users such as households, i.e., subscriptions.

5 With regard to DOCSIS's clumsy bandwidth allocation, signal distribution between end users is greatly facilitated.

Thus, the CATV network portion based on the coaxial cable can advantageously provide a transmission path for the Ethernet data signal, which is separable and manageable in a manner suitable for the available network topology and cabling for further distribution of the Ethernet signal to households. The examples below illustrate the advantages of using such a network arrangement to circumvent the constraints imposed by various network topologies on the provision of da-15 connections. In any case, the great advantage of the user interface is that no cable modem is needed for data connections, but the existing coaxial cable network can be utilized for broadband data transmission.

20 From the network operator's point of view, data connection management is simplified because active cable modems no longer need to maintain a re - *: · register and cable modems do not need to reserve time slots. for upstream channel requests, i.e. DOCSIS-! *! ·. the so-called system. The request-grant process can be omitted completely.

· "·, 25 Since a certain number of destination addresses (e.g., 10-20 IP addresses) are allocated a single modulated data channel transmitted in a coaxial cable, new users do not have to make reservations as in the CMTS; ··· * address time division can be organized much more efficiently compared to DOCSIS, and the system latency will be reduced as the request-grant process that causes the delay can be omitted from C !.

·· • · • ··] ···. In addition, adding new data interfaces to the system is easy and inexpensive. When a certain number of new subscribers arrive 35, a new Ethernet branch can be formed for them, with a dedicated channel for the broadband Ethernet signal. In this context, it is also possible to redistribute new and old subscription subscribers 119313 9 between new and existing channels, provided that this can optimize the distribution of data signals to different subscription subscribers. The capacity increase is flexible and no additional and expensive CMTS hardware is needed when existing capacity runs out.

5

The network arrangement according to the invention also provides a upstream data channel from a household connection through an access network to an Et-hernet terminal modem EAM and from there through a coaxial cable connection back to an Ethernet network modem ENM. The Ether-10 net-terminal modem EAM shown in Figure 2b naturally comprises a modulator for the reverse channel used in the coaxial-cable connection, and the Ethernet network modem ENM shown in Figure 2a, respectively, comprises a demodulator. Accordingly, by logically combining two 256-QAM modulated 50 Mbps channels, a symmetric 100 to 15 Mbps capacity is provided in both directions. If, on the other hand, the reverse channel does not require the same bandwidth and data rate as the downstream data channel, for example, only one 50 Mbps channel may be used on the reverse channel or QPSK modulation (or 16-QAM-20 modulation) providing lower data rates like DOCSIS .

It will be apparent to one skilled in the art that the above examples of an 8 MHz channel and 256-QAM modulation are only one embodiment of the invention. . ·. embodiments thereof. Obviously, the available channel bandwidth may vary depending on, for example, the TV system (e.g. NTSC 6.4 • · ·

Mhz) and, on the other hand, a modulation other than 256-QAM- * * ··· * modulation, either more efficient or less effective. In addition, while it is possible to meet current and near-term broadband communication needs cost-effectively by using two signal components per Ethernet-C! 1 terminal modem, the number of signal components in the future: ·! Ββ may also be higher than today. presented two. Thus, many of these I ···. Because of these variables, different embodiments of the invention may vary T such that a baseband signal 35 output from one Ethernet terminal modem may have a data rate greater than or equal to 100 Mbps.

119313 10

The following illustrates various embodiments for connecting the network arrangement of the invention to various CATV network arrangements implemented in the close proximity of household connections (the so-called last 100 meters). The invention is not limited to the following Example 5 but is intended to illustrate how the network arrangement of the invention can advantageously be applied to a wide variety of access networks.

In Fig. 3, the network arrangement is connected to a coaxial social access network implemented as a star network, by means of which the Ethernet signal and the CATV signal are further distributed to houses 300, 302, 304 and 306. This enables the Ethernet output signal of the Ethernet terminal modem EAM and CATV from the CATV network. signal to a common distribution point EMT (Ethernet Multitap) and utilizes 15 solutions known from Fl 20045502. In this solution, an Ethernet signal supplied to a distribution point over a broadband data network is transmitted bidirectionally to a computer in a coaxial access network such that a baseband data signal transmitted over a cable network is filtered by a bandpass filter and combined with a filtered CATV signal to form a interconnect. Similarly, in the reception of a combined signal (in a household interface), the baseband data signal and the CATV signal are separated from the combined signal by means of filters, whereby the data signal is supplied to a computer. ! ·. typically via a network interface card and a CATV signal to the TV.

· "*. 25 Further, the coaxial access network provides a reverse data channel • · · * 'V from the household connection through the distribution point back to the Internet operator.

In this way, the coaxial access network can be utilized to transmit both the CATV signal 9 9 * ··· * and, for example, a computer-controlled data signal without a cable modem. Since baseband data signal transmission does not require modulation / demodulation, cheap passive filters can be used for coupling / isolation and expensive and power-consuming cable modems are not required.

In Fig. 4, the network arrangement is connected to a coaxial access network in the form of a tree, or cascade, network, by means of which the Ethernet signal and CATV's ”signal are further distributed to houses 400, 402, 404 and 406. the Ethernet signal from the EAM switch and the CATV signal from the 119313 11 CATV network can be connected to a common distribution point, but the passive filter solution described in Fl 20045502 does not work on a cascade network because the access network includes multiple splitters before the home interface. Instead, the access network may employ the solution of WO2004 / 080075, which utilizes transceivers for power network communication (PLC) with modems to generate OFDM modulated data that can be transmitted alongside a TV signal in ka-10 game television media.

In Figure 5, the network arrangement is utilized by distributing the CATV signal over a coaxial access network and feeding the Ethernet data signal into, for example, a telephone exchange 500 of a block of flats and from there to a local area network (LAN) of the house. The LAN can be implemented in many different ways. One arrangement that is suitable for almost all apartment buildings is a broadband LAN implemented using HomePNA technology (ITU-989.1 standard), where an Ethernet signal is fed into the house telephone network through a HomePNA switch. HomePNA technology does not set high requirements for cabling of 20 telephone networks, but a standard Cat 1 pair is sufficient to implement a LAN on an existing telephone network. Ho ·: * mePNA uses the higher frequencies 5.5 - 9.5 MHz of the twin cable so that the Ho · «·· mePNA traffic and the lower frequency telephone services do not cause interference. On the other hand, most new Apartment Houses are built with telephone • cabling (eg Cat5 paired cabling), which also allows LAN traffic to be transmitted over the telephone network at the same time (so-called IRB, Internet Ready Building). ·· * The connection may include a LAN hub (repeater and / or switch) to convey LAN traffic.

O! · 30:. * Γ The above examples (HomePNA and IRB) are intended to illustrate embodiments that seek to make the most of mass-based cabling. The network arrangement according to the invention * Y * for introducing a broadband data signal into a 35 local area network is of course not limited to these examples, but *: * ·; it can also be applied in situations where new cables need to be pulled between the access points.

119313 12

Figure 6 shows another embodiment for applying the network arrangement according to the invention. The network arrangement disclosed therein provides a Broadband Ethernet data connection to a Broadband LAN 5 (WLAN) base station 500. Such a solution is particularly useful for establishing various WLAN Hot Spots at locations with a large number of potential WLAN users such as hotels, airports, trains and buses. car stations, etc.

It will be obvious to a person skilled in the art that as technology advances, the basic idea of the invention can be implemented in many different ways. The invention and its embodiments are thus not limited to the examples described above, but may vary within the scope of the claims.

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Claims (17)

119313 13 A communication system for transmitting a data signal in a cable television television signal transmission in an adapted coaxial cable network, the communication system comprising a coaxial cable connection (108) for distributing the cable television signal to a cable television network distribution point (114); characterized in that the communication system comprises a first data network switching point (102) for supplying a baseband broadband data signal (202) to said communication system; a modulation unit (ENM) for generating a modulated data signal from said baseband broadband data signal (202), the modulated data signal comprising at least two signal components (212,214) logically connected but modulated for different communication channels; a connector (106) adapted for said coaxial cable connection to adapt signal components of said modulated data signal to its own frequency channels for transmission on said coaxial cable connection; a separator fitted to said coaxial cable connection for separating the signal components of said modulated data signal into separate signals; An M. · 'demodulation unit (EAM) for demodulating and combining said signal components (222, 224) into a baseband ΐ'ΐ wideband data signal (232); and: * · *: a second data network switching point (118) for forwarding a baseband wide band data signal to at least one node of the data processing device. *:!: * 30 • · The communication system according to claim 1, characterized by: * ·· that the signal components comprise data packets which are in- | ·. 35 channels to have substantially the same time delay for each of the signal components. 119313 14 Telecommunication system according to claim 1 or 2, characterized in that the modulated data signal comprises two 50 Mbps signal components modulated by 256-QAM modulation to 8 MHz bandwidth data channels. The communication system according to any one of claims 1 to 3, characterized in that said modulated data signal comprises data intended for predetermined destination addresses which is modulated on its own frequency channel. The telecommunications system according to any one of claims 1 to 4, characterized in that said second data network switching point is integrated with said cable television network distribution point, wherein said integrated data network switching point (EMT) is arranged to combine said baseband data signal and cable television signal 20 to one node on a cable TV network. A communication system according to any one of claims 1 to 4, characterized in that said second data network connection point is an integrated mains connection; 25 cable television network distribution point, whereby said integrator. . ·. a data network switching point (EMT) arranged to modulate said. baseband data signal for power network communication (PLC) to be transmitted by modulation and to transmit modulated data signal and cable. . a vision signal for at least one node in the cable television network. • · · Ϊ:; 30 A communication system according to any one of claims 1 to 4, characterized in that said second data network switching point is arranged in a feed. said baseband data signal to at least one telephone network node to distribute the data signal over the telephone network to the home subscriptions. 119313 15 A communication system according to claim 7, characterized in that said at least one telephone network node comprises a HoPeNA switch. 5 Telecommunication system according to claim 7, characterized in that said at least one telephone network node comprises a local area network hub. 10 Modulation unit adaptable to a coaxial cable network, characterized in that the modulation unit (200) comprises an input terminal (202) for supplying a baseband wideband data signal to said modulation unit; 15 separating means (204) for dividing a baseband broadband data signal into at least two separate signal components, modulating means (206, 208) for modulating said signal components (212, 214) on different communication channels; and a control unit (210) for controlling said separator means and modulation means so that said signal components can be logically combined into a single data signal. 9 ♦ * » Modulation unit according to claim 10, characterized in that ··· • j *; 25, said modulation means are arranged to supply data packets comprising said signal components to their own frequency channel -. ** ·. still, the channel parameters of which are selected to provide substantially the same time delay for each signal component. • · • · · Modulation unit according to claim 10 or 11, characterized in that said modulation means are arranged to modulate a data signal comprising two 50 Mbps signal components, which are. modulated by 256-QAM modulation for 8 MHz bandwidth • »· * ·: · * 35 communication channels. • ♦ 119313 16 Modulation unit according to one of claims 10 to 12, characterized in that said control unit is arranged to control the logical connection of said signal components based on Ethernet MAC addresses 5. A coaxial cable network adaptable demodulation unit, characterized in that the demodulation unit (220) comprises at least two inputs for supplying at least two separate 10 modulated signal components (222, 224) to said demodulation unit, said signal components being logically combinable into a single data signal; demodulation means * (226, 228) for demodulating said signal components into baseband signal components; Combining means (230) for combining baseband signal components into a wideband data signal (232); and a control unit (234) for controlling said demodulation means and combining means to combine said signal components into a single data signal. 20 Demodulation unit according to claim 14, characterized in that said combining means are arranged to combine demodulated data packets comprised by said signal components essentially:. 25 women in their first come first served order. IM · • * · • · · Demodulation unit according to claim 14 or 15, characterized in that said signal components comprise a 50 Mbps data signal modulated by a 256-QAM modulation for an 8 MHz bandwidth data transmission channel. t · •. ·· *. Demodulation unit according to one of Claims 14 to 16, characterized in that said control unit is configured to control the logical connection of said signal components based on Ethernet MAC addresses. 119313 17