WO2012079782A1

WO2012079782A1 - Method and device for distribution of multimedia communication channels in a passive optical network

Info

Publication number: WO2012079782A1
Application number: PCT/EP2011/060232
Authority: WO
Inventors: Carlos MARÍN ARRIAZA; José Alfonso TORRIJOS GIJÓN; Manuel SÁNCHEZ YANGÜELA
Original assignee: Telefonica, S.A.
Priority date: 2010-12-17
Filing date: 2011-06-20
Publication date: 2012-06-21
Also published as: AR084327A1

Abstract

Method and system for the distribution of multimedia communication channels, e.g. TV digital channels, through a passive optical network (e.g. GPON). The present invention try to solve the technical problems related to PPV or customized multimedia services, including new functionalities in the optical access network termination point, the ONT. These functionalities are specifically targeted to permit the usage of the ONT PPV capable as an end user device for a basic PPV service with standard Digital TV decoders (e.g. the ones already integrated in DTT TV sets).

Description

METHOD AND DEVICE FOR DISTRIBUTION OF MULTIMEDIA

COMMUNICATION CHANNELS IN A PASSIVE OPTICAL NETWORK

D E S C R I P T I O N

TECHNICAL FIELD

The present invention relates generally to communication signals distribution and more particularly to a method and device for the transmission and reception of television channels in a Passive Optical Network (PON).

DESCRIPTION OF THE PRIOR ART

Networks for television channels broadcasting that are currently available can be classified into four categories:

• Terrestrial broadcast networks, which use a regulated frequency band, like current analogue television and DTT (Digital Terrestrial Television) in accordance to DVB-T (Digital Video Broadcast - Terrestrial) standard released by ETSI (European Standards Telecommunications Institute).

• Satellite broadcast networks.

• Cable TV networks, based on HFC (Hybrid Fibre Coaxial) networks.

• And recently, IPTV (IP Television) systems which allow incumbent telecommunications operators to provide to their basic telephone service customers, television channels over IP using broadband accesses based on digital subscriber line (DSL) technologies over metallic pairs.

Meanwhile telecommunications operators are now deploying new optical access networks in order to improve their service portfolio. This optical access networks will replace current access networks based on copper twisted pairs.

Some of these new access networks based on optical fibre do not use any active device that must be remotely fed, and that's why these networks are called Passive Optical Networks (PON) which have a point to multipoint topology.

International Telecommunications Union has standardized these optical access networks over fiber with a point to multipoint topology. This standard is known as GPON (Gigabit capable Passive Optical Networks, ITU-T G.984.1 ) and it includes the available wavelengths for information transmission in both ways, downstream (from the network to the user) and upstream (from the user to the network). In this standard, the access network termination point at customer premises is the

ONT (Optical Network Termination). In the evolution process that telecommunications operators are now undertaking, they are matching their IPTV systems developed for broadband accesses based on DSL technologies to the new frequencies and capacities provided by GPON access networks.

ITU-T included enhancement bands for optical access based on GPON standard in 2007 (ITU-T G.984.5 Enhancement band for gigabit capable optical access networks), as it was previously done with the enhancement band for BPON optical access, Broadband Passive Optical Networks.

The enhancement bands open the way for new mechanisms for RF Television (TV) channels distribution services over passive optical networks with a point to multipoint topology. RF Television (TV) currently uses two formats:

• The analog one, in which a RF carrier, either in the VHF { Very High Frequency) or UHF {Ultra High Frequency) bands, is modulated analogically by the video and audio signals, either using AM {Amplitude Modulation) or FM {Frequency Modulation) modulation schemes.

· And the digital one, in which a RF carrier, either in the VHF or UHF bands, is modulated digitally by a set of digital TV contents, typically in MPEG (Motion Picture Experts Group) format, using QPSK {Quadrature Phase-Shift Keying), QAM {Quadrature Amplitude Modulation) or COFDM (Coded Orthogonal Frequency Division Multiplexing) modulation schemes.

In the case of analog TV there are different TV formats like NTSC ( National Television System Committee) in USA, Canada, Mexico and Japan; PAL {Phase Alternating Line), with different implementations in the different geographical areas in Europe or China and SECAM (Sequentiel Couleur Avec Memoire) in France, Russia, Belarus or Morocco. But all of those systems use 6MHz, 7 MHz and 8 MHz width channels in the VHF and UHF bands. And that's the reason why all the commercial TV sets 600 include a frequency tuner that covers a frequency range which starts typically at 47 MHz and ends at 870 MHz. In the case of Digital Terrestrial Television (DTT), there are different standards like DVB-T (Digital Video Broadcasting - Terrestrial) in Europe, Australia and India, ATSC (Advanced Television Standards Committee) in USA, Canada and Mexico, or ISDB-T (Integrated Services Digital Broadcasting - Terrestrial) in Japan, Brazil, Argentina, Chile and Peru. The progressive replacement of analog television by the digital one is reducing the available RF channels for television services.

So, in those countries where DTT is being deployed in accordance to ETSI DVB-T standard and analog TV is being suppressed, the number of RF channels available for television is reduced to (in figure 1 , the current frequency assignment for Digital Terrestrial Television is shown):

• Eight 7 MHz channels, from 174 MHz to 230 MHz, in the VHF /// band or High Band (frequency range 'C in Figure 1 ).

• Seventeen 8 MHz channels, from 470 MHz to 606 MHz in the UHF IV band (frequency range 'F' in Figure 1 ).

• And thirty three 8 MHz channels in the UHF V band, from 606 MHz to 870 MHz ('G' and 'H' frequency ranges in Figure 1 ).

In Spain, available spectrum for digital television is even lower: DTT can only use the frequency range comprised between 470 and 862 MHz ('F' and 'G' frequency ranges in Figure 1 ).

In a first stage this reduction will be balanced by the fact that using DTT, a RF channel can support simultaneously several digital television and radio channels, instead of a unique analog channel. But this balance will disappear progressively as broadcasters move from Standard Definition (SD) television to High Definition (HD) television or 3D television. At that point, each RF channel can support only one HD television channel using MPEG-2 coding format, or two HD television channels using MPEG-4/H.264 coding format. Digital terrestrial television services use a licensed band. So it is not possible to ignore this regulation meanwhile television signals are radio transmitted signals. In the same way, it cannot be ignored the deadline for the analog television service decided by different National Regulatory Authorities. The capacity decrease will be higher if finally part of the frequency range initially reserved for DTT is re-assigned for mobile communication services, a reassignment which is also known as Digital Dividend (see figure 2):

• Area 1 (Europe): Spectral reassignment of the frequency band between 790 to 862 MHz for mobile services (nine 8 MHz channels, from channel 61 to 69, both inclusive). In Spain this spectral reassignment will happen before January the 1 ^st of 2015.

• Area 2 (America): Spectral reassignment of the frequency band between 698 to 806 MHz for mobile services (eighteen 6 MHz channels).

• Area 3 (Asia-Pacific): Spectral reassignment of the frequencies band between 790 to 862 MHz for mobile services, and in some countries the frequencies band between 698 to 806 MHz.

The usage of current IPTV solutions over the new fiber access networks based on PON (as for example, on Gigabit Capable Passive Optical Networks GPON) poses some problems:

• IPTV contents demand access bit rates which reduce in a significant way available bandwidth for other services. So, access bit rate increase provided by PON access networks can be not enough to provide High Definition multi-room IPTV services in an efficient economic way. Efficient economic way means a passive optical point to multipoint network with a high split ratio that permits to share the same network equipment, known as OLT (Optical Line Termination) 40, between as many end users as possible, making the price per connected user as small as possible.

• IPTV solutions require a decoder (Set Top Box or STB) per each TV set at home. The usage of Set Top Boxes is expensive because it supposes a high investment costs due to Set Top Boxes purchase and high operational costs due to STBs upgrades and breakdowns, which many times involves the displacement of specialized staff at customer premises. The aforementioned enhancement bands offer the possibility of transmitting several TV channels multiplex by means of DTT. But this possibility is only valid for broadcast TV. If a Pay Per View service is demanded or different groups of TV channels want to be offer (bundling), it will be necessary to include additional control mechanisms which means again the usage of STBs, with the operational costs previously explained.

SUMMARY OF THE INVENTION

The present invention uses a new method and system that will reduce or eliminate the deficiencies of current tools.

Figure 3 shows, as an example of PON network, the general GPON architecture including both conventional RF capable GPON ONT 50 (as in the standards GPON architecture) and new RF and PPV capable GPON ONT 70 (as proposed in the present invention).

The present invention try to solve the technical problems related to PPV or customized (packaging) multimedia services previously explained, including new functionalities in the XPON optical access network termination point, the GPON ONT 50. These functionalities are specifically targeted to permit the usage of the XPON ONT PPV capable 70 as an end user device for a basic PPV service with standard Digital TV decoders (e.g. the ones already integrated in DTT TV sets) so no additional STB is needed.

.Hence, the main problems found in the prior art systems, are solved.

In order to implement such functionalities, the present invention includes an interferences generator block (PPVC) 75 in a RF capable GPON ONT 50, which origins a RF and PPV capable GPON ONT 70:

• This block 75 generates several RF signals in the frequency band used by DTT (in Europe, typically the UHF frequency range, from 470 MHz to 862 or 870 MHz). • Each of these signals have a central frequency inside the frequency range occupied by one of the DTT multiplex transmitted by the GPON access network, so each of these signals is interfering a DTT multiplex (that is, a DTT multiplex will be interfered by the signal whose central frequency is inside the frequency range of the DTT multiplex). In an exemplary embodiment, the central frequency of the signals will correspond to central frequency of one of the DTT multiplex transmitted by the PON access network.

• Later, the interference signals are combined with de whole RF signal obtained by the video services receiver 55 preventing that the corresponding DTT channels can be played by the customer's DTT decoder.

• The central frequency of each interfering signal can be programmed and activated or deactivated by means of the usage of new OMCI (ONT Management Control Interface) commands which may be generated by a new OMCI managed entity. These commands will include parameters to indicate the multiplex to be interfered, (eg. PPV channel or group of channels), if it must be activated or deactivated (interference respectively deactivated or activated) and the duration of activation for PPV service. Because of the nature of this kind of contents (sports events, live performances, etc.) the activation of the corresponding multiplex must be carried out for a limited period of time.

Hence, the present invention offers the Digital Terrestrial Television (DTT) Pay Per View or other multimedia services, for example over GPON enhancement band, without DTT re-modulation in the RF capable PON ONT 70. The addition of the PPVC block allows, by means of the generation of several interferences, the selection of a set of digital TV channels transmitted over the same DTT multiplex or RF channel (in DTT, typically UHF).

In a first aspect, it is presented a Optical Network Terminal, ONT, belonging to a passive optical network which distributes multimedia communications channels, the Terminal comprising at least an input/output optical port for receiving a signal from the optical network and means for extracting from said signal a first radiofrequency signal composed by a plurality of multimedia communication channels, the Optical Network Terminal further comprising: A module which comprises m signal generators called Interference Generators, IG, being m a design parameter, each Interference Generator generates, if activated, one or more signals, called interfering signals, each interfering signal having a certain bandwidth and a certain central frequency, the central frequency of each interfering signal being inside the frequency range occupied by one of the multimedia communication channels transported by the first radiofrequency signal;

Control means for configuring the parameters for the generation of the interfering signals of each Interference Generator and for activating or deactivating the generation of each interfering signal;

A first combiner which adds all the signals generated by the m Interference generators;

A second combiner which adds the first radiofrequency signal and the signal generated by the first combiner to generate a second radio frequency signal, being therefore this second radio frequency signal an interfered signal where the multimedia communication channels whose frequency range includes the central frequency of any of the interfering signals generated by the Interference generators, will be interfered.

In a second aspect, it is presented a method for the distribution of multimedia communications channels in a passive optical network, the network having at least an Optical network Terminal ONT, the method comprising the following steps:

- The ONT receiving a signal from the optical network and extracting from said signal a first radiofrequency signal composed by a plurality of multimedia communication channels

- Control means situated in the ONT configuring the parameters of m signals generator called Interference Generators situated in the ONT and activating or deactivating the generation of signals by each interference generator, where m is a design parameter - Generating by each activated Interference Generator, IG, one or more signals, called interfering signals, with a certain bandwidth and with a certain central frequency, the central frequency of each interfering signal being inside the frequency range occupied by one of the multimedia communication channels transported by the first radiofrequency signal

- Adding the signals generated by the m Interference generators by a first combiner;

- Adding the first radiofrequency signal and the signal generated by the first combiner, by a second combiner, to generate a second radio frequency signal, being therefore this second radio frequency signal an interfered signal where the multimedia communication channels whose frequency range includes the central frequency of any of the interfering signals generated by the Interference generators, will be interfered

Finally, a computer program comprising computer program code means adapted to perform the above-described method is presented.

Further aspects of the invention are described in the dependent claims.

For a more complete understanding of the invention, its objects and advantages, reference may be had to the following specification and to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

To complete the description and in order to provide for a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the description and illustrate a preferred embodiment of the invention, which should not be interpreted as restricting the scope of the invention, but rather as an example of how the invention can be embodied. The drawings comprise the following figures: Figure 1 shows a graphic representing the current frequency assignment for Digital Terrestrial Television is shown):

Figure 2 shows a graphic representing the future frequency assignment for Digital Terrestrial Television, after the so called Digital Dividend.

Figure 3 shows a block diagram of a General GPON architecture with RF capable

ONT and RF and PPV capable ONT as proposed in one embodiment of the present invention.

Figure 4 shows a block diagram of the PPVC according to one embodiment of the present invention.

Figure 5 shows a graphic representing the RF spectrum obtained at ONT's in different scenarios according to one embodiment of the present invention.

Corresponding numerals and symbols in the different figures refer to corresponding parts unless otherwise indicated.

DETAILED DESCRIPTION OF THE INVENTION

Current invention consists of a change into a RF capable GPON ONT 50 equipped with a receiver 55 for video services over the GPON enhancement band. The change consists of the addition of one block PPVC (Pay Per View Control) 75 which allow, by means of the generation of several interferences, the selection of DTT multiplex, to obtain a RF and PPV capable GPON ONT 70.

As it can be seen in figure 3, the GPON architecture is composed by at least an Optical line Termination OLT (40), a distribution optical network 20 with at least an optical splitter 30 and several Optical Network Terminals ONT 50, 70. The OLT is in charge of managing the network, performing several functionalities as resources assignment, synchronization, remote configuration, distribution of the channels and contents of a telecommunication operator. It has optical receiver and transmitter connected to a Wavelength Division Multiplexer WDM and the control logic necessary for the operations ("Logic" block in figure 3). The output of this OLT will be a signal in an intermediate frequency that we will call I F_GPON.

The OLT with the capacity to distribute the channels and contents of a telecommunication operator V-OLT, 45, further comprise a video transmitter (V-Tx). The output of this OLT will be a signal in an intermediate frequency that we will call IFVIDEO₎, connected to a second Wavelength Division Multiplexer WDM.

These output signals will be distributed over an Optical Distribution Network (ODN). The complementary structure is found in the ONT, which comprise optical receiver and transmitter (65), connected to a Wavelength Division Multiplexer WDM, and the logic control to operate the different elements. If the ONT has the capacity to receive content of a telecommunications operator (TDT channels), it will further comprise a video receiver (55) and optionally wavelength blocking filters, WBF. The goal of the present invention is to implement a contents distribution service (e.g.

Pay per View contents) using an optical carrier in the GPON enhancement band, without any external decoder (i.e. STB) and without any kind of DTT re-modulation. An interference Generator 85 permits to eliminate, among the whole range of DTT RF channels, one specific RF channel which transports one or several digital TV channels selected by end user. The invention requires a contents selection mechanism which allows end users to select dynamically the TV channel they want to see. As it has been explained previously, the preferred embodiment of current proposal uses the generation of several interferences as the mechanism to control the activation and deactivation of DTT multiplex. Furthermore, the central frequency of each one of the interferences and its status (activated or deactivated) will be controlled through OMCI (ONT Management Control Interface) commands generated by an OMCI managed entity. The activation of an interference implies the deactivation of the DTT multiplex whose frequency range includes the central frequency of the interfering signal.

Figure 4 shows the module that must be added to a conventional RF capable GPON ONT 50, in order it can support DTT PPV services over the GPON enhancement band without any kind of DTT re-modulation, obtaining an RF and PPV capable GPON ONT 70. This module is called Pay Per View Control (PPVC) 75.ln this embodiment of the invention, a GPON network is used as an example, but any other types of Passive Optical Networks could be used.

The first step consists of the addition of an Interferences Generator and Control (IGC) block 80. The Interferences Generator and Control IGC 80 is composed by m Interference Generators (85) (IGi , IG₂,..., IG_m), generating in total n interfering signals (being m<=n, because a single interference generator can generate several interfering signals) where n means the total number of DTT multiplex that can be controlled (i.e. interfered), activated or deactivated (e.g. in Spain n would preferably be between 1 and 49). This number (n) will depend on the implementation carried out (for instance it can be designed the RF and PPV capable GPON ONT 70 that will be able to control 5 DTT multiplex, other model 10, 15...). In the example, exposed in figure 4, m=n, that is, each interference generator generates 1 interfering signal.

Each IG 85 can generate, if activated, (one or more interfering signals) an interfering signal with:

• A certain bandwidth BW (see detail D, figure 5), for example, in an exemplary embodiment BW could be 1 MHz.

• A power level sufficient to impede the contents visualization of the DTT multiplex being interfered by the signal. For example, a power level higher that the one of the DTT multiplex being interfered by the signal

• A central frequency, in the band used by DTT (in Europe, typically the UHF frequency range, from 470 MHz to 862 or 870 MHz), that is inside the frequency band occupied by the DTT multiplex to be interfered. In an exemplary embodiment the central frequency of the interfering signal corresponds to the central frequency of DTT multiplex to be interfered. The value of this frequency will be defined in the appropriated parameter of an OMCI command.

Each interference can be activated or deactivated by means of the corresponding OMCI commands (this commands will be typically received at GPON block 65, because this block is the standard part of ONT that transmits and receives the PON stream. After receiving the commands, it will send it to the corresponding block, in this case, block 75) that includes the suitable aforementioned parameters (central frequency, power level, bandwidth...) for the generation of interfering signals and for activating or deactivating the generation of each interfering signal. Next, all interfering signals generated by the IGC, are added by means of an adder or combiner 90, generating a new RF interfering signal that contains all the activated interferences (spectrum B, figure 5). Interfering signal, in this way generated, is added by means of another adder or combiner 95 with the RF signal obtained in V- Rx 55 (spectrum A, figure 5), which is composed by the whole DTT multiplex transmitted from V-OLT block 45.

This new RF multiplex thus obtained contains both the digital open TV channels and the PPV channels requested by end user, which are interfered by the corresponding signals IG1 to IGn (spectrum C figure 5). DTT multiplex interfered in this way can't be played by DTT decoder because of the interfering signal, put on top of DTT multiplex, prevents it.

In order to activate a DTT multiplex, it is needed to deactivate the corresponding interference (spectrum C figure 5). The order will be sent from OLT with an OMCI command that includes the suitable aforementioned ME parameters. For the opposite action (DTT multiplex deactivation) will be needed the activation of the corresponding interference by means of the aforementioned procedure.

Figure 5 C shows the RF spectrum obtained at ONT's 70 RF output when the customer has subscribed a determined multiplex and the operator has activated it by means of an OMCI command, that supposes the deactivation of the corresponding

IG 85. Whereas the other PPV channels remain deactivated and the customer's DTT decoder is not able to play it. This mechanism permits a simplified selection (Pay Per View) service consisting of the access to a set of digital TV channels (DTT channels) transmitted in the same RF channel. If the RF channel transports a MPEG Transport Stream made of only one digital TV channel (i.e. a HDTV or High

Definition TV channel), only one digital TV channel is available. But if the selected RF channel carries a MPEG Transport Stream consisting of a multiplex of several digital TV channels (i.e. several SDTV or Standard Definition TV channels), end user can see all the digital channels transported by the selected RF channel.

The preferred option is the case of homes connected through point to multipoint passive optical networks which receive television signal, both broadcast or pay per view, through BPON enhancement band, GPON (ITU-T G.984.5) enhancement band, XG-PON systems enhancement band or any other wavelength range that in the future can be specified for overlay video distribution signals over optical fibre access networks.

As it has been explained previously, coaxial point to multipoint access networks can also benefit from current invention, but it is not the preferred option because coaxial cables can radiate digital television signals and disturb other signals distributed through the radioelectric spectrum and so point to multipoint coaxial networks, only in the last drop inside buildings.

The proposed invention increases the performance for Digital Television services for those broadcasters which use wired (fiber and coaxial) access networks. So, with the improvements included in current proposal, a RF and PPV capable GPON ONT 70 can select a RF channel modulated by a DTT multiplex (a MPEG Transport Stream). But the selected contents decoding is performed by the DTT (DVB-T) receiver included by customer television set (user interface, that is, it is not necessary to decode or demodulate the signals on RF and PPV capable GPON

ONT 70 for selecting the DTT multiplex.

Summarizing, the main advantages of the invention are: · The addition of a set of interference generators permits the implementation of a PPV service without any external decoder or STB. The STB suppression simplifies the service and also reduces the cost of this type of services. The cost reduction is achieved by two ways: the suppression of STB purchase and simplifying the service operation.

· Moreover the suppression of the DTT re-modulation, reduces even more the provision cost of a DTT PPV service over the GPON enhancement band.

• Current proposal provides a new and more complete way to deploy multi- room digital TV services, both open TV and PPV TV, with standard quality (SDTV) and also with high definition quality (HDTV). The deployment is made from the very network without any additional decoder or STB at customer premises. End user requires exclusively a RF and PPV capable GPON ONT 70 with the modifications included in current proposal. Service is not dependant on customer premises equipment updates, with the subsequent savings in the service operation. • As it has been explained in the previous paragraph, this proposal is valid for both broadcast TV and PPV services and so it would allow the provision of both services, reducing significantly the CAPEX (Capital expenditures) and OPEX (Operational expenditures) costs of current IPTV services provided by telecommunications operators, and in addition to this, taking advantage of DTT economies of scale. So this innovation provides a competitive advantage to those telecommunication operators which deploy optical fibre access networks.

Although the present invention has been described with reference to specific embodiments, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions in the form and detail thereof may be made therein without departing from the spirit and scope of the invention as defined by the following claims.

Claims

1 . Optical Network Terminal, ONT, belonging to a passive optical network which distributes multimedia communications channels, the Terminal comprising at least an input/output optical port for receiving a signal from the optical network and means for extracting from said signal a first radiofrequency signal composed by a plurality of multimedia communication channels, the Optical Network Terminal further comprising: A module which comprises m signal generators called Interference Generators, IG, being m a design parameter, each Interference Generator generates, if activated, one or more signals, called interfering signals, each interfering signal having a certain bandwidth and a certain central frequency, the central frequency of each interfering signal being inside the frequency range occupied by one of the multimedia communication channels transported by the first radiofrequency signal;

A first combiner which adds all the signals generated by the m Interference generators; A second combiner which adds the first radiofrequency signal and the signal generated by the first combiner to generate a second radio frequency signal, being therefore this second radio frequency signal an interfered signal where the multimedia communication channels whose frequency range includes the central frequency of any of the interfering signals generated by the Interference generators, will be interfered.

2. The Optical Network Terminal according to claim 1 where each multimedia communication channel may carry a single Digital Terrestrial Television, DTT, channel or a multiplex of a group of Digital Terrestrial Television, DTT, channels.

3. The Optical Network Terminal according to claim 2 where the multimedia communication channels carry the Digital Terrestrial Television, DTT, channels in the form of a MPEG Transport Stream.

4. The Optical Network Terminal according to any of the previous claims where the first and second radio frequency signals will be in the frequency band used by the Digital Terrestrial Television, DTT channels or in the UHF or VHF frequency band

5. The Optical Network Terminal according to any of the previous claims, where the central frequency of each interfering signal correspond to the central frequency of one of the multimedia communication channels transported by the first radiofrequency signal.

6. The Optical Network Terminal according to any of the previous claims where the control means are managed by ONT Management Control Interface, OMCI, commands, the OMCI commands including the parameters needed to configure the Interference Generators

7. The Optical Network Terminal according to claim 6 where the parameters included in the OMCI command, further includes the duration of the activation of each Interference generator

8. The Optical Network Terminal according to claim 6 where the parameters included in the OMCI command, includes the multimedia communication channel to be interfered by each interfering signal.

9. The Optical Network Terminal according to claim 6 where the OMCI command is transmitted by an Optical Line Termination, OLT, node and received by the ONT through the optical network

10. The Optical Network Terminal according to any of the previous claims where the bandwidth of the signals generated by the interference generators will be big enough, so the multimedia channels interfered by the signal generated by the interference generators will not be playable by an user equipment when receiving the second radio frequency signal.

1 1 . The Optical Network Terminal according to any of the previous claims where the control means will configure the central frequency of the interfering signals so multimedia channels opens to all the users will not be interfered and where the control means will configure the central frequency of the interfering signals so said multimedia channels which correspond to pay per view channels or selected channels to which the first user has no access, will be interfered

12. The Optical Network Terminal according to any of the previous claims where each Interference Generator generates only one interfering signal.

13. The Optical Network Terminal according to any of the previous claims where the passive optical network is a Gigabit capable Passive Optical Network and the frequency bands used in the Passive Optical Network for the multimedia channel distribution are the enhancement bands for optical access based on Gigabit capable Passive Optical Network.

14. Method for the distribution of multimedia communications channels in a passive optical network, the network having at least an Optical network Terminal ONT, the method comprising the following steps:

15. A computer program comprising computer program code means adapted to perform the method according to claim 14 when said program is run on a computer, a digital signal processor, a field-programmable gate array, an application-specific integrated circuit, a micro-processor, a micro-controller, or any other form of programmable hardware.