Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via frequency channels
Patent
1997-01-13
1999-08-31
Nguyen, Chau
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via frequency channels
370522, 370538, 370208, 348385, 348 7, H04J 1100
Patent
active
059463260
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to data transmission utilizing a digital transmission channel that enables the transmission of audio and data services and the selective reception of these services. The information transmitted on the transmission channel can either be in a continuous data stream or packet form.
2. Description of the Related Art
In the digital audio system DAB (Digital Audio Broadcasting), developed for using frequency bands efficiently, the transmission path is completely digital and the system is intended to replace the present generally used analog broadcast system using frequency modulation. The DAB is especially designed for a mobile environment, that is, the receiver can be mobile so that different attenuations and disturbances produced by the propagation of a radio signal can be prevented by the combined effect of suitable modulation and channel coding. A DAB receiver is capable of enduring several echoes originating from the same source and thus a country-wide radio coverage can be achieved with one frequency channel since the signal of stations other than the one to be listened to is interpreted as an echo and will be eliminated.
The DAB determines the digital radio channel, based on many carriers, that is suitable for the. transmission of both audio and data services. A completely digital transmission channel may be either a continuous data stream or packet channel. Packet switching is more flexible and more easily enables the transmission of data units of a finite length. The transmission, transfer and reception of the DAB system is explained in detail in Kimmo Hakkarainen, MSc Thesis, A Channel Encoder/Decoder for DAB Demonstrator, 1995, Tampere University of Technology, pages 2 to 13. For the receiver the highest abstraction level of the DAB system is called an ensemble. One ensemble is divided into several services and each service is further divided into service components. A service component is either an audio channel or a data channel.
FIG. 1 discloses one DAB system in a simplified way. At the transmission end a control device 1 controls the transmission. A FIC and control block 2 produces SI (Service Information) information relating to audio and data services, Multiplex Configuration Information MCI and CA (Conditional Access) information relating to conditional access that can be information relating to chargeability/encryption of the services. Taken together, they form a fast information channel FIC. Audio information, such as music, supplied by producers 3 of audio services is compressed in a MPEG encoder 4 and is led to audio channel encoders 5. Similarly, the data supplied by producers 6 of data services is encoded in data channel encoders 7. The channel encoded data, audio and FIC information are led to a block carrying out orthogonal frequency division multiplexing OFDM. The OFDM symbol produced by an inverse fast Fourier transformation of the block is a group of subcarriers with an exactly determined duration. Individual subcarriers are modulated by a D-QPSK (Differential Quaternary Phase Shift Keying) method and at the end it results in a DAB transmission signal that comprises successive transmission frames. Each frame is time multiplexed between a synchronization channel, a fast information channel FIC and a channel MSC (Main Service Channel) containing audio and data services. Transmission mode I intended for a radio network on the ground using one frequency has 1,536 carriers, a frame has 76 symbols and the duration of a frame is 4* 24 ms=96 ms. Transfers can be made in the frame. Mode II intended for ground-level and satellite transmissions has 384 carriers, a frame has 76 symbols and the duration of a frame is 24 ms. 55,296 MSC bits and 1,024 FIC bits are transferred in a frame. Mode III intended for ground-level, satellite and cable transmissions has 192 carriers, a frame has 153 symbols and the duration of a frame is 24 ms. 55,296 MSC bits and 1,024 FIC bits are transferred in a frame.
The signal receiv
REFERENCES:
patent: 4713758 (1987-12-01), De Kelaita
patent: 5124943 (1992-06-01), Lubarsky
patent: 5359601 (1994-10-01), Wasilewski et al.
patent: 5400401 (1995-03-01), Wasilewski et al.
patent: 5446888 (1995-08-01), Pyne
patent: 5452288 (1995-09-01), Rahuel et al.
patent: 5799192 (1998-08-01), Yasuda
Kimmo Hakkarainen, "A Channel Encoder/Decoder for DAB Demonstrator", Mar. 1995, pp. I-51.
Nguyen Chau
Nokia Telecommunications Oy
Vu Thinh
LandOfFree
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