EP1334579A1

EP1334579A1 - Device and method for wireless broadcast on a number of carrier waves

Info

Publication number: EP1334579A1
Application number: EP01979151A
Authority: EP
Inventors: Jan Ossfeldt; Per Ruottinen; Christina Wittborn
Original assignee: Teracom AB
Current assignee: TB Invent AB
Priority date: 2000-10-23
Filing date: 2001-10-22
Publication date: 2003-08-13
Also published as: SE0003816D0; WO2002041547A1; AU2002211138A1

Abstract

the invention relates to a device comprising means for wireless broadcast on a number of carrier waves, a so-called multi-carrier broadcast, of a time multiplexed data stream, the multiplex (16), to a number of receivers. The invention further comprises means (15) for dividing the data stream into frames 822), and means (5, 6, 7, 8, 9, 13, 15) for letting certain frames contain information regarding the senders that are part of the time multiplexing. The invention is characterized in that the device comprises means (11) for gathering an dplacing all said information at a location known to the receiver in the frames (22) that contain such information.

Description

DEVICE AND METHOD FOR WIRELESS BROADCAST ON A NUMBER OF CARRIER WAVES

TECHNICAL FIELD

The present invention relates to a method for wireless broadcast on a number of carrier waves, a so-called multi-carrier broadcast, of a time multiplexed data stream, the multiplex, to a number of users. The method comprises division of the data stream into frames, and supplying some frames with information regarding the senders that are part of the time multiplexing. The invention solves problems that occurs at previously known methods which are inflexible and without dynamics. The invention also relates to a method for reception of a broadcast according to above, and means to realize the method.

BACKGROUND ART

At broadcast of radio and TV today, it is possible to make digital broadcasts, which may be transmitted on a number of frequencies at the same time with a number of carrier waves, a so-called multi-carrier broadcast, from one and the same or a number of different transmitters. Characterizing for all the broadcasts concerning radio and TV, is that it is a one-way communication from the transmitter to a number of receivers, a so-called broadcast system, where the receiver has the possibility of making certain choices, and where a digital broadcast system provides more opportunities than an analogue broadcast system.

In connection with digital broadcasts, one separates between DAB, Digital Audio Broadcast, digital broadcasts of audio, and DVB, Digital Video

Broadcast, digital TV broadcasts. Both DAB and DVB are based on similar methods for transferring a certain amount of data from a transmitter to one ore more mobile or stationary receivers. The digital broadcast may be done in a way previously known by dividing a large amount of information in the form of data into smaller data packages, frames, of which certain frames contain a head where the information regarding the order in which the frames are to be assembled by a receiver is present, and other necessary information. A DAB transmission, e.g. for radio, or a DVB transmission, e.g. for TV, to a number of receivers is done in the form of a multiplexed broadcast, which means that a number of applications may send data via a sole unit that adds data, multiplexes, from all the applications and thereafter broadcasts everything in a stream of data, preferably time multiplexed. The time multiplexed stream of data, called the multiplex, thus contains a mixture of data from the different applications, which have to be separated, i.e. be demultiplexed, in such a way that the receiver may identify information from the different applications.

Within several existing distribution systems for digital broadcasts, digital broadcast systems, there is a possibility of tunnelling IP traffic, i.e. protocols for internet traffic consisting of a frame with address information, i.e. where in the frame certain information lies, and remaining information. Tunnelling refers to a technique for enclosing datagrams in a protocol at the same level or a higher level and sending these enclosed datagrams via the transport system, which may be viewed upon as a tunnel between two nodes in a network. The datagrams are then enclosed at the starting point and de- enclosed at the end point. When tunnelling using the DAB technique, the tunnel is created between the data packet encoder, Packet Mode Encoder, and the data packet decoder, Packet Mode Decoder. Since the broadcast systems by nature are suited for one-way distribution, this opportunity is mainly used for distributing traffic with UDP/IP multicast protocols. A UDP/IP protocol is a connectionless transport protocol, which admits an application to send enclosed pure IP datagrams, i.e. frames with IP protocols, without necessarily establishing a connection to the receiver. For a time multiplexed broadcast of DAB and DVB, respectively, there is a possibility to signal to the receiver which services a DAB multiplex and a DVB multiplex, respectively, contain, and where that information is retrieved in the multiplex, which is done by configuring the receiver in advance to read said information at certain predetermined positions in the multiplex. If IP traffic is transmitted in the multiplex, the receiver may analyse that IP traffic is distributed, and where in the multiplex it is recovered, using the transmitted information. In order to utilize services distributed with IP multicast, the receiver also has to, in other words, know IP multicast addresses and UDP gate numbers. Using previously known technology, the receiver thus has to be configured with IP multicast addresses and UDP gate numbers known in advance, which configuration has to be made by the manufacturer or the user. The receiver thus has to be configured by the manufacturer or the user when a change in the multiplex is done for IP multicast addresses or when UDP gate numbers are changed, which leads to a quite inflexible system with a lot of extra work for manufacturer and user. As an example, it may be mentioned that a user that not continuously follows and makes the changes of IP addresses and UDP gate numbers that take place in the multiplex, loses the possibility to watch which new services that are offered, or loses the possibility to watch old services that has changed IP address or UDP gate number, and thus misses many of the advantages that DAB and DVB admit, respectively.

There is thus a problem present with previously known technology in the form of an inflexible system without dynamics, which results in disadvantages for both manufacturer and user. It would then be preferable if the input of IP addresses and UDP gate numbers for the receiver could be performed in a way that spares the manufacturer from re-configuring the receiver and spares the user from following and continuously performing the alterations mentioned above. DISCLOSURE OF INVENTION

A main purpose of the present invention is to provide a flexible and dynamic system comprising a transmitting device comprising means for wireless broadcast on a number of carrier waves, a so-called multi-carrier broadcast, of a time multiplexed data stream, the multiplex, to a number of receivers, further comprising means for dividing the data stream into frames, and means for letting certain frames contain information regarding the senders that are part of the time multiplexing where the disadvantages mentioned above are removed. The transmitting device also comprises means for gathering and placing all said information at a location known to the receiver in the frames that contain such information.

The advantages thus attained are that the supplier may change information regarding the senders that are part of the multiplex without the user having to perform corresponding changes at the receiver, which is necessary for previously known systems, which leads to a high degree of flexibility for the system for both the user and the supplier, together with large dynamics in the system.

The invention also relates to a receiving device, comprising means for reception of a wireless broadcast on a number of carrier waves, a so-called multi-carrier broadcast, of a time multiplexed data stream, the multiplex, intended for a number of receivers, preferably broadcasted by a transmitting device according to above, further comprising means for dividing the data stream into frames, and means for reading information regarding the senders that are part of the time multiplexing in frames comprising said information. The receiving device comprises means for reading all said gathered information at a location known to the receiver in the frames that contain such information. The present invention also relates to a method for using the device according to the invention.

The device and method according to the invention may be devised in different ways, but below a description of a preferred ambodiment referring to the enclosed figures is given.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described in connection to examples of preferred embodiments and the enclosed figures, there

Fig. 1 schematically shows a block diagram for a transmitting device for digital wireless broadcast of audio according to previously known technology.

Fig. 2 schematically shows a block diagram for a receiving device for reception of digital wireless broadcast of audio according to previously known technology.

Fig. 3 schematically shows an example of how a frame in a DAB multiplex may look like according to the invention.

MODES FOR CARRYING OUT THE INVENTION

Below, the invention will be described in greater detail starting from an embodiment example, which shall not be regarded upon as limiting for the invention, but only as a support for the description of the invention. Figure 1 and 2 show schematical block diagrams for devices according to previously known technology, which is used in the present invention, while figure 3 in greater detail describes the invention. In the text below, previously known technology in Fig. 1 and 2 will first be explained briefly, after which Fig. 3 is explained in greater detail together with a complete report on the present invention. Fig.1 and 2 will thereafter be described in greater detail.

Fig. 1 shows schematically a block diagram for a device for digital wireless broadcast of audio in the form of electromagnetic signals on a number of carrier waves, a so-called multi-carrier broadcast. The broadcast comprises a time multiplexed data stream, the multiplex, to a number of receivers. The transmitting device comprises a number of devices which are shown in the block diagram in Fig.1 and consists of; audio generator 1 ; audio encoder 2; audio channel encoder 3; first time divider 4; data encoder 6; data channel encoder 7; second time divider 8; MUX 9; control configurator 10; FIC generator 11 ; MUX control 12; frequency divider 13; sync generator 14; OFDM 15, comprising means for generation of a signal called the multiplex 16, which shall be transmitted to a number of receivers at a broadcast, e.g. a DAB signal (DAB multiplex) for radio and transmitter 17.

Fig. 2 shows schematically a block diagram for a device, receiving device, for reception of digital wireless broadcast of audio on a number of carrier waves, a so-called multi-carrier broadcast, of a time multiplexed data stream, the multiplex 16, intended for a number of receivers, preferably broadcasted by a transmitting device according to above. The receiving device comprises a number of devices which are shown in the circuit diagram in Fig. 2 and consists of; tuner 18, comprising means for reception of the multiplex 16; A/D-FFT 19; T/F demodulation/signal decoder 29 and user control control 21.

Fig. 3 shows schematically an example of how a frame 22 in a DAB multiplex may look like. The frame 22 consists of a synchronization channel 23 containing information from the sync generator 14, a "Fast Information Channel (FIC)" 24 containing information regarding the configuration of the multiplex and certain information regarding services, respectively, and a channel called "Main Service Channel (MSC)" 25 comprising channels for audio data e.g. radio channel one 26, radio channel two 27, etc., which channels also may contain other data information, e.g. information regarding services.

The FIC 24 comprises information from the FIC generator 11 and comprises a so-called "Multiple Configuration Information (MCI)" (not shown), which describes the contents of the multiplex. In the FIC there is also some information regarding services, so-called "Service Information (SI)" 28.

The services mentioned are delivered by different senders, which may deliver different text messages or links to different services of e.g. internet type. The services are supplied via the transmitting device where the computer generator 5 transforms the information to a suitable data format, preferably an IP protocol where the senders' IP multicast addresses for reception and UDP gate numbers are of special interest since these are necessary for enabling the receiver to use the services that are offered.

The present invention relates to the possibility of gathering information for all IP data streams regarding where in the multiplex datagrams with a certain IP multicast address and UDP gate number may be recovered and thereafter place the gathered information at a location in the multiplex. The present invention thus implies that a receiving device, e.g. such as mentioned above, only has to be configured to retrieve the information at one and the same location in order to get all the information regarding where in the multiplex datagrams with a certain IP multicast address and UDP gate number are. Advantages with this is that if the supplier wants to change IP addresses and UDP gate numbers, respectively, and their location in the multiplex, nothing changes for the receiver, who looks at the same location in the multiplex and acquires new information regarding where in the multiplex the new IP addresses and the UDP gate numbers, respectively, may be recovered. The receiving device may thus follow dynamically when changes occur, which grants a possibility to dynamically store the new information, and in that way be updated regarding changes all the time.

The present invention relates to gathering and placing all information regarding the senders that are part of the time multiplexing, i.e. IP multicasting addresses and UDP gate numbers, on a location known to the user in the frames containing such information. The information regarding the senders that are part of the time multiplexing may also contain information regarding links to services available in the time multiplex.

According to the present invention, the information regarding the senders in the frame that are part of the time multiplexing is placed as a part of FIC 24, Fast Information Channel. In the FIC, the information is preferably placed in SI 28, and in SI 28 preferably in User Application Data in User Application Information in FIG 0/13, Fast Information Group 0/13. There is no need to place the information in all frames, but the number of frames containing such information may vary.

According to previously known technology, the receiving device for said broadcasts has been configured in advance to find information in the multiplex. In order to use the services that are provided in the broadcast, it has, according to previously known technology, been necessary for the supplier to always place information at the same locations in the multiplex if the already configured receiver shall be able look at the correct locations and gather the information. The information that is of current interest for being gathered by the user at broadcasts that provide services, is preferably IP multicasting addresses which concern receiver addresses in an IP protocol that provides services, and UDP gate numbers. Previously, this kind of information has thus been located at pre-selected locations in one or some channels spread in the multiplex, which has forced the user to re-configure his receiving device when the supplier has changed or added some information of the type IP multicast addresses and UDP gate numbers, respectively, which implies disadvantages in the form of an inflexible system without dynamics.

In order to make the understanding of the invention easier, a more detailed description follows for Fig. 1 and 2, which show previously known technology that also is used in the present invention.

Fig. 1 shows schematically a block diagram for a device, a transmitting device, for digital wireless broadcast of audio in the form of electromagnetic signals on a number of carrier waves, a so-called multi-carrier broadcast. The broadcast comprises a time multiplexed data stream, the multiplex, to a number of receivers. The transmitting device comprises a number of devices connected according to the block diagram in Fig. 1 , which devices are;

-audio generator 1 , comprising means for audio generation of one or more linear digital audio signals, which device may consist of one or more devices that generates audio digitally, e.g. recordings of voice and music; -audio encoder 2, comprising means for encoding the linear digital audio signals, audio encoder 2, from the audio generator 1 , to other formats of digital audio signals, e.g. MPEG, which encoding also states the character of the audio signal, e.g. mono or stereo sound;

-audio channel encoder 3, comprising means for encoding the audio channels which consist of parts of the digital audio signal and additional information, e.g. extra protection of some of the parts that are part of the source coded digital audio signal in the channel;

-first time divider 4, comprising means for time division of the digital audio signals from the audio channel encoder 3, i.e. the digital audio signals are divided into smaller parts with a certain time interval and are mixed in order to distribute possible errors;

-data generator 5, comprising means for data generation of one or more linear data streams, which device may consist of one or more devices which generate linear data streams for different purposes, e.g. such information regarding services that the supplier wants to include, e.g. advertisement, programme schedules or links to senders of information or services or control means for a receiver of the data streams; -data encoder 6, comprising means for encoding the data streams from the data generator 5 to other formats of data streams, which also may state the character of the data stream, e.g. if the data stream is of a text message type or of a control means type; -data channel encoder 7, comprising means for encoding data channels which consist of parts of the data stream and additional information, e.g. extra protection of some of the parts that are part of the source coded data signal in the channel;

-other time dividers 8, comprising means for time division of the data streams from the data channel encoder 7, i.e. the data streams are divided into smaller parts with a certain time interval and are mixed in order to distribute possible errors;

-MUX 9 comprising means for time multiplexing of the digital audio signals which emanate from the first time divider 4 and the data streams that emanate from the second time divider 8, i.e. the digital audio signals are woven together with the data streams in a way that is controlled via the MUX; -control configurator 10, comprising means for configuring control functions, which configuration contains information for controlling the MUX; -FIC generator 11 , comprising means for generation of channels containing information regarding the construction of the time multiplex and also information regarding where in the time multiplex certain information may be found and possibly control information for the channel, said FIC generator 11 is not based on time division;

-MUX control 12, comprising means for controlling the MUX, which controls the time multiplexing according to the information from the control configurator 10, which information is forwarded to the FIC generator 11 together with synchronization information for the FIC in relation to the MUX; -frequency divider 13, comprising means for frequency division, which puts together the data stream with information regarding services from the FIC generator 11 with the time multiplex, i.e. the combined text data stream and audio data stream from the MUX 9, to a common data stream, the frequency multiplex, where the time independent information regarding services from the FIC generator always is found at the same location in relation to the time divided data streams that emanate from the MUX 9, where the frequency divider 13 divides the multiplex on a number of different carriers with different frequencies; -synch generator 14, comprising means for generation of synchronization symbols;

-OFDM 15, comprising means for dividing the frequency multiplex into frames and where the OFDM 15 comprises means for adding the synchronization symbols to the frames with the method "Orthogonal Frequency Division Multiplexing" (OFDM), which method modulates individual orthogonal carriers for the different frames, which in turn provides a final product in the form of a signal, the multiplex 16, which shall be transmitted to a number of receivers during a broadcast, e.g. a DAB signal for radio; -transmitter 17, comprising means for broadcasting the multiplex, e.g. in the form of a DAB signal.

Fig. 2 shows schematically a block diagram for a device, a receiving device, for reception of digital wireless broadcast of audio on a number of carrier waves, a so-called multi-carrier broadcast. The broadcast comprises a time multiplexed data stream, the multiplex 16, intended for a number of receivers, preferably broadcasted by a transmitting device according to above. The receiving device comprises a number of devices connected according to the circuit diagram in Fig. 2, which devices are; -tuner 18, comprising means for reception of the multiplex 16; -A/D-FFT 19, comprising means for transforming an analogue signal to a digital signal (A/D transformation) and a unit for fourier transformation "Fast Fourier Transformation (FFT)"; -T/F demodulation/signal decoder 20, comprising means for time and frequency demodulation and means for decoding the digital audio streams, encoded in the audio encoder 2 and the data streams, encoded in the data encoder 6, which T/F demodulation/signal decoder 20 brings back the time divided and frequency divided encoded signal, via division of the data stream into frames, to respective original linear digital audio streams and data streams, respectively, which thus become available for a user in a suitable way, e.g. a radio with a text display;

-user control control 21 , for user interface comprising means for control and synchronization of the devices that are part of the receiving device.

The invention is not limited to what has been shown in the embodiment example above, but may vary within the scope of the claims. It may be mentioned, for example, that the present invention is described emanating from a DAB multiplex, but also may be used for a DVB multiplex, i.e. a digital broadcast for TV, "Digital Video Broadcast". However, for DVB it may be necessary to change the actual location for storage of information, but the invention as such is applicable anyway for storing said information at a location in the multiplex as a pointer for where in the multiplex certain information is located.

Claims

1. Device comprising means for wireless broadcast on a number of carrier waves, a so-called multi-carrier broadcast, of a time multiplexed data stream, the multiplex (16), to a number of receivers, further comprising means (15) for dividing the data stream into frames (22), and means (5, 6, 7, 8, 9, 13, 15) for letting certain frames contain information regarding the senders that are part of the time multiplexing characterized in that the device comprises means (11) for gathering and placing all said information at a location known to the receiver in the frames (22) that contain such information.

2. Device comprising means for reception of a wireless broadcast on a number of carrier waves, a so-called multi-carrier broadcast, of a time multiplexed data stream, the multiplex (16), intended for a number of receivers, preferably broadcasted by a device according to claim 1, further comprising means for dividing the data stream into frames (22), and means for reading information regarding the senders that are part of the time multiplexing in frames comprising said information characterized in that the device comprises means for reading all said gathered information at a location known to the receiver in the frames (22) that contain such information.

3. Device according to any one of the preceding claims, characterized in that the device comprises means for letting the information regarding the senders that are part of the time multiplexing comprise IP multicasting addresses at which broadcast is done.

4. Device according to any one of the preceding claims, characterized in that the device comprises means for letting the information regarding the senders that are part of the time multiplexing comprise UDP gate numbers at which broadcast is done.

5. Device according to any one of the preceding claims, characterized in that the device comprises means for letting the information regarding the senders that are part of the time multiplexing comprise information regarding links to services available in the time multiplex.

6. Device according to any one of the preceding claims, characterized in that the information regarding the senders in the frame that are part of the time multiplexing is placed as a part of FIC (24), Fast Information Channel.

7. Device according to claim 6, characterized in that the information regarding the senders in the frame that are part of the time multiplexing is placed as a part of SI (23), Service Information.

8. Device according to claim 7, characterized in that the information regarding the senders in the frame that are part of the time multiplexing is placed as User Application Data in User Application Information in FIG 0/13, Fast Information Group 0/13.

9. Device according to any one of the preceding claims, characterized in that the time multiplexed data stream is DAB, Digital Audio Broadcast.

10. Device according to any one of the claims 1-5, characterized in that the time multiplexed data stream is DVB, Digital Video Broadcast.

11. Device according to any one of the claims 2-10, characterized in that the receiver stores information regarding the senders that are part of the time multiplexing.

12. Method for wireless broadcast on a number of carrier waves, a so-called multi-carrier broadcast, of a time multiplexed data stream, the multiplex, to a number of receivers, which method comprises;

-division of the data stream into frames, -supplying certain frames with information regarding the senders that are part of the time multiplexing, characterized in that ;

-all said information is gathered and placed in a location known to the receiver in the frames that contain such information.

13. Method for reception of a wireless broadcast on a number of carrier waves, a so-called multi-carrier broadcast, of a time multiplexed data stream, the multiplex, intended for a number of receivers preferably broadcasted by a method according to claim 12, which method comprises; -division of the data stream into frames, -reading information in frames comprising information regarding the senders that are part of the time multiplexing, characterized in that;

-all said gathered information is read at a location known to the receiver in the frames that contain such information.

14. Method according to any one of the claims 12 to 13, characterized in that;

-IP multicasting addresses are placed as information regarding the senders that are part of the time multiplexing.

15. Method according to any one of the claims 12 to 14, characterized in that;

-UDP gate numbers are placed as information regarding the senders that are part of the time multiplexing.

16. Method according to any one of the claims 12 to 15, characterized in that;

-information regarding links to services available in the time multiplex are placed in the information regarding the senders that are part of the time multiplexing.

17. Method according to any one of the claims 12 to 16, characterized in that;

-the information regarding the senders in the frame that are part of the time multiplexing is placed as a part of FIC, Fast Information Channel.

18. Method according to any one of the claims 12 to 17, characterized in that;

-the information regarding the senders in the frame that are part of the time multiplexing is placed as a part of SI, Service Information.

19. Method according to any one of the claims 12 to 18, characterized in that;

- the information regarding the senders in the frame that are part of the time multiplexing is placed as User Application Data in User Application Information in FIG 0/13, Fast Information Group 0/13.

20. Method according to any one of the claims 12 to 19, characterized in that; -the time multiplexed data stream, on which the method is applied, is DAB, Digital Audio Broadcast.

21. Method according to any one of the claims 12 to 16, characterized in that; -the time multiplexed data stream, on which the method is applied, is DVB, Digital Video Broadcast.

22. Method according to any one of the claims 12 to 21, characterized in that;

- the receiver stores information regarding the senders that are part of the time multiplexing.