Method and telecommunications network for carrying a digital broadcast signal

Abstract

 The object of the invention is a method and a telecommunications network (1) for carrying a digital broadcast signal to a wireless terminal device (5). In the method, at least one transmitter (4) transmits a digital broadcast signal and at least one wireless terminal device (5) receives said digital broadcast signal. Further, in the method at least one receiver (7) receives the digital broadcast signal transmitted by the transmitter (4) and carries the received digital broadcast signal to at least one master antenna network (3). An antenna means (6) forwards the digital broadcast signal received from the master antenna network (3) to the wireless terminal device (5) over the air.

Description

Field of the invention

[0001] The present invention relates to a method according to the preamble of appended claim 1 for carrying a digital broadcast signal to a wireless terminal device. The invention also relates to a telecommunications network according to the preamble of appended claim 6 .

Background of the invention

[0002] In future communications, digitalization will play an important role. Telecommunications networks and services are already mostly digitalized; the digitalization of the television and radio will be completed in about 5 to 10 years. The digital television standard in Europe is DVB. In practice, the digitalization of television networks, i.e. building of DVB networks (Digital Video Broadcasting), means that the transmitters and the consumers' receiving sets are converted to digital.

[0003] The most important DVB standards are DVB-S, DVB-C and DVB-T. DVB-S (Digital Video Broadcasting - Satellite) is the first of the DVB standards. DVB-S is described by the "onion model". The actual message lies in the core of the onion, and the layers around the core protect the signal and adjust it for the transmission. All data to be transported has been packaged as a standard-form MPEG-2 transport stream. Upon transmission, the data is first formatted into a standard-form structure. The content is then scrambled and error-correction is added to the package. Finally, the signal is modulated to the satellite carrier wave using QPSK modulation (Quadrature Phase Shift Keying).

[0004] DVB-C (Digital Video Broadcasting - Cable) is based on DVB-S but uses different modulation (QAM - Quadrature Amplitude Modulation). Also, package error correction is not needed.

[0005] DVB-T (Digital Video Broadcasting - Terrestrial) is based on the above standards but, again, it uses different modulation (OFDM - Orthogonal Frequency Division Multiplexing). Further, it is optimized for different transmission environments, which makes it a noteworthy candidate for even a worldwide standard for traditional TV broadcasting.

[0006] In addition, the first mobile phones with television reception functionality are being developed for the market. In Europe, these mobile phones will deploy IPDC technology (IP Datacast) in DVB-H network (Digital Video Broadcast - Handheld) using the DVB-H broadcast standard. The standard is based on the terrestrial DVB-T standard, but it has been modified to enable battery-saving functions in the receiving sets, for example, and to allow the terminal devices to move at even a high speed. Consequently, DVB-H is particularly well suited for wireless terminal devices. IPDC makes it possible to use digital television broadcast technology to broadcast Internet, or IP-based data to a large number of users of wireless terminal devices at a high speed of up to 12 Mbit/s. Mobile data services broadcast to several or all subscribers are part of the advancement brought about by digital TV technology and the associated efficient use of frequencies.

[0007] Mobile IPDC services are designed for use in wireless terminal devices provided with a digital TV receiver. A new digital terrestrial network using the DVB-H standard is therefore needed. The network will be very different from the current television networks, for the signal reception requires a considerably higher field strength, better indoor coverage and mobility support. The design of the DVB-H network will be based on low-power transmitters and gap fillers. This kind of network is closely related to current mobile communications networks. This means that even in a country of the size of Finland, the network will comprise at least hundreds, maybe even thousands of base stations. Building such a network with good coverage requires considerable economic efforts and lasts long, especially if a good indoor coverage familiar to us from mobile communications is to be achieved.

Brief description of the invention

[0008] An object of the current invention is to provide a method and a telecommunications network with which at least some of the above problems can be overcome. A specific object of the invention is to provide a method and a telecommunications network with which the indoor coverage of the DVB-H network can be greatly improved in an easy and cost-effective manner.

[0009] The invention is based on the idea that an existing master antenna system or cable television network (hereafter jointly referred to as a master antenna system) is used for carrying a DVB-H signal in buildings where improved indoor coverage is needed. The signal can be supplied to the master antenna network using the same channel as is used in the original DVB-H transmission. The DVB-H signal is carried from the master antenna network to a wireless terminal device using retransmitting antennas or gap fillers. The DVB-H signal can be supplied to a retransmitting antenna or gap filler either from normal antenna sockets of the master antenna network or alternatively from access points separately installed for them.

[0010] More specifically, the method of the current invention is primarily characterized by what is stated in the characterizing part of appended claim 1. The telecommunications network of the current invention, in turn, is primarily characterized by what is stated in the characterizing part of appended claim 6.

[0011] With the present invention, major advantages are achieved over the methods of the prior art. The indoor coverage of the DVB-H network can be improved very cost-effectively, because the indoor coverage may be improved only in those places where it is necessary, using inexpensive antennas or gap fillers. The indoor coverage and quality can be easily improved even in those places that are the most problematic in respect of wireless data transmission, such as the basement of a building. Further, the users can improve the indoor coverage of the DVB-H network on their own initiative, independently of the operator.

List of figures

[0012] In the following, the invention is described in greater detail with reference to the attached drawings, where

Fig.1

shows a telecommunications network according to a preferred embodiment of the invention.

Detailed description of the invention

[0013] Fig. 1 shows a telecommunications network where the invention can be applied. In the figure, the example is illustrated by means of a block diagram. The detailed structure and operation of the individual blocks are known per se or can be arranged for the operation according to the present invention based on this description. A more detailed implementation is obvious to a person skilled in the art from the following description, and it may vary, so a more detailed description is not needed. In the description, the DVB-H standard is used only by way of example. The invention can thus also be applied to other corresponding wireless broadcasting networks.

[0014] A telecommunications network 1 comprises at least a digital wireless broadcasting network 2 (hereafter: DVB-H network) and a master antenna network 3. The DVB-H network comprises at least one transmitter 4, at least one wireless terminal device 5, at least one receiver 7 and at least one antenna means 6. The transmitter 4 here refers to an actual transmitter of the DVB-H network or to a gap filler. The receiver 7 and the antenna means 6 are connected to the master antenna network 3. The receiver 7 receives a DVB-H signal that the transmitter 4 has transmitted preferably over the air and carries it in the appropriate format to the master antenna network 3. In the master antenna network 3 the signal is preferably carried using the same channel as is used in the original DVB-H transmission. The antenna means 6 receives the DVB-H signal carried by the master antenna network 3, filters out the other signals of the master antenna network 3 and retransmits the desired signal over the air to at least one wireless terminal device 5.

[0015] Said antenna means 6 can be arranged in problematic places, such as the basement of a building or a space in the middle of a large building where the field strength of the DVB-H network 2 is otherwise weak. In these places, the antenna means 6 is connected to the master antenna network 3 preferably via a TV antenna socket. After this, the antenna means 6 can receive the DVB-H signal carried in the master antenna network 3. Before forwarding the signal, the antenna means 6 performs effective filtering on the received signal, with the aim of separating out the DVB-H signal to be forwarded from the other signals of the master antenna network. The filtering is preferably performed using bandpass filtering. The wireless terminal device 5 can now receive the DVB-H signal transmitted from the antenna means 6. The wireless terminal device 5 cannot detect that the received DVB-H signal has passed through the master antenna network 3. From the point of view of the wireless terminal device 5 the situation is the same as when the wireless terminal device 5 receives a DVB-H signal directly from the transmitter 4. Another essential point is that the wireless terminal device 5 can receive the same DVB-H signal from at least two sources 4, 6 substantially simultaneously, whereby the DVB-H signals received from the sources 4, 6 are summed together to form a stronger overall signal in the wireless terminal device 5.

[0016] The antenna means 6 can be a parasitic antenna, if a sufficiently high field strength of the DVB-H network is achieved with it in a desired space. If the parasitic antenna does not provide a sufficient field strength as such, a separate or built-in gap filler, amplifying the signal received from the master antenna network, can additionally be used as the antenna means 6. The field strength of the signal output from the antenna means 6 is then adjusted in the gap filler as required by the space in question. As the number of antenna means 6 is not limited, antenna means can be connected even to all antenna sockets of the master antenna network 3. If necessary, access points can be added preferably by using the regular techniques of building a master antenna network. In other words, the desired indoor coverage can also be improved by arranging several antenna means 6 appropriately in the desired space.

[0017] Obviously, the current invention is not limited to the above embodiments but can be varied within the scope of the attached claims.

Claims

1. A method of carrying a digital broadcast signal to a wireless terminal device (5), with at least one transmitter (4) transmitting a digital broadcast signal and at least one wireless terminal device (5) receiving said digital broadcast signal, the method being characterized in that the digital broadcast signal transmitted by the transmitter (4) is received by at least one receiver (7), the digital broadcast signal received by said receiver (7) is carried to at least one master antenna network (3) and the digital broadcast signal received from the master antenna network (3) is forwarded over the air by at least one antenna means (6) to the wireless terminal device (5).

2. A method according to claim 1, characterized in that before forwarding the signal, the antenna means (6) perform filtering to separate out the desired digital broadcast signal to be forwarded from the other signals of the master antenna network (3) preferably using bandpass filtering.

3. A method according to claim 1 or 2, characterized in that before forwarding the signal, the antenna means (6) amplify said digital broadcast signal received from the master antenna network (3) to increase the field strength.

4. A method according to claim 1, 2 or 3, characterized in that the digital broadcast signal is a DVB-H signal.

5. A method according to claim 1,2, 3 or 4, characterized in that the digital broadcast signal is carried to the master antenna network (3) using the same channel as is used by the original digital broadcast signal transmitted by the transmitter (4).

6. A telecommunications network (1) comprising at least a wireless broadcasting network (2) that comprises at least one transmitter (4) and at least one wireless terminal device (5) receiving a digital broadcast signal transmitted by the transmitter (4), characterized in that the telecommunications network (1) further comprises at least one master antenna network (3), at least one means (7) for carrying the digital broadcast signal transmitted by the transmitter (4) to the master antenna network (3) and at least one means (6) for carrying the digital broadcast signal from the master antenna network (3) to the wireless terminal device (5).

7. A telecommunications network (1) according to claim 6, characterized in that the telecommunications network (1) further comprises at least one means (6) for separating out the digital broadcast signal received from the master antenna network (3) from the other signals of the master antenna network (3) preferably using bandpass filtering.

8. A telecommunications network (1) according to claim 6 or 7, characterized in that the telecommunications network (1) further comprises at least one means (6) for amplifying the digital broadcast signal received from the master antenna network (3).

9. A telecommunications network (1) according to claim 6, 7 or 8, characterized in that the digital broadcast signal is a DVB-H signal.

10. A telecommunications network (1) according to claim 6, 7, 8 or 9, characterized in that the telecommunications network (1) further comprises at least one means (7) for carrying a digital broadcast signal using the same channel as is used by the original digital broadcast signal transmitted by the transmitter (4).

Drawing