Simultaneous broadcasting system, transmitter and receiver therefor

• US 6,256,508 B1
• Filed: 11/17/1998
• Issued: 07/03/2001
• Est. Priority Date: 02/27/1998
• Status: Expired due to Fees

• Current Assignee: Masao Nakagawa
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Oguchi, Masashi, Koyama, Atsumi, Abe, Masanori, Nakagawa, Masao, Oonaka, Satoru, Mori, Masashi
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): BEAMER, TEMICA M
• Application Number:
  US09/192,511
• Time in Patent Office: 959 Days
• Field of Search: 455/502, 455/503, 455/67.1, 455/67.3, 455/67.6, 370/203, 370/208, 370/478, 375/260, 348/21
• US Class Current: 370/312
• CPC Class Codes: H04H 20/67 Common-wave systems, i.e. using separate transmitters operating on substantially the same frequency
• CPC Class Codes: H04H 2201/20 digital audio broadcasting [DAB]

Abstract

A simultaneous broadcasting system, a transmitter, and a receiver therefor use a first frequency bandwidth for a wide area broadcasting and a second frequency bandwidth for a local area broadcasting obtained by dividing a frequency bandwidth of one broadcasting channel. In the simultaneous broadcasting system, a same program for the wide area broadcasting is transmitted based on an OFDM modulation method by using the first frequency bandwidth and a different program for each local area station is transmitted by using a different spreading code allocated for each local are station based on a SS modulation method.

Claims

1. A simultaneous broadcasting system in which a plurality of broadcasting stations broadcast a same program as a wide area broadcasting and each of said broadcasting stations broadcasts a different program as a local area broadcasting by using one broadcasting channel, simultaneously, said simultaneous broadcasting system comprises:

dividing a frequency bandwidth of said broadcasting channel into a first frequency bandwidth for said wide area broadcasting and a second frequency bandwidth for said local area broadcasting; and

modulating signals of said same program for said wide area broadcasting in said first frequency bandwidth based on an Orthogonal Frequency Division Multiplex (OFDM) method, and signals of said different program in said second frequency bandwidth based on a Spread Spectrum (SS) method by using different spreading codes corresponding to said local area broadcasting stations.

2. A simultaneous broadcasting system as claimed in claim 1, wherein said second frequency bandwidth for said local area broadcasting is used for data transmission transmitted from each of said plurality of broadcasting stations.

3. A simultaneous broadcasting system as claimed in claim 1, wherein a different spreading code is allocated for each user contracted with each station of said plurality of broadcasting stations, and said second frequency bandwidth for said local area broadcasting is used for a down link in a two-way communication between said each broadcasting and said each user.

4. A simultaneous broadcasting system as claimed in claim 1, wherein a broadcasting area of each of at least one or more said broadcasting stations is divided into a plurality of sectors, and each broadcasting station broadcasts different programs to each sector by using different spreading codes corresponding to each sector based on said SS method.

5. A simultaneous broadcasting system as claimed in claim 1, wherein said second frequency bandwidth allocated for said local area broadcasting is further divided into a plurality of sub-frequency bandwidth, and each broadcasting station broadcasts a different local area broadcasting program based on a Frequency Division Multiple Access (FDMA) method in each of said plurality of sub-frequency bandwidth allocated for each broadcasting station.

6. A simultaneous broadcasting system as claimed in claim 1, wherein said second frequency bandwidth allocated for said local area broadcasting is further divided based on a Time Division Multiplex Access (TDMA), and each broadcasting station broadcasts a different local area broadcasting program based on said TDMA method.

7. A broadcasting transmitter for transmitting a same program as a wide area broadcasting from a plurality of broadcasting stations and a different program as a local area broadcasting from one of said plurality of broadcasting stations by using one broadcasting channel, simultaneously, comprising:

an Orthogonal Frequency Division Multiplex (OFDM) modulator for modulating broadcasting signals, based on a OFDM modulation method, for said wide area broadcasting in a first frequency bandwidth obtained by dividing a frequency bandwidth of said broadcasting channel;

a Spread Spectrum (SS) modulator for modulating signals for said local area broadcasting by using a different spreading code allocated corresponding to each of said broadcasting stations based on a SS modulation method in a second frequency bandwidth obtained by dividing said frequency bandwidth of said broadcasting channel; and

a frequency synthesizer for synthesizing signals from said OFDM modulator and signals from said SS modulator and for outputting synthesized signals.

8. A broadcasting transmitter as claimed in claim 7, wherein said SS modulator comprises a plurality of SS modulators for modulating said signals for said local area broadcasting, said frequency synthesizer, for synthesizing said signals from said wide area broadcasting and said signal from said local area broadcasting corresponding to each broadcasting station, comprises a plurality of frequency synthesizer, each frequency synthesizer is formed corresponding to each of said plurality of SS modulators, and further comprises a plurality of directional antennas, and wherein each directional antenna corresponds to a pair of each SS modulator and each frequency synthesizer.

9. A broadcasting transmitter as claimed in claim 7, wherein a Frequency Division Multiple Access (FDMA) modulator is incorporated instead of said SS modulator, wherein said OFDM modulator modulates said signals for said local area broadcasting by using one of a plurality of sub-broadcasting frequency bandwidths obtained by dividing said second frequency bandwidth allocated for each of said plurality of broadcasting stations.

10. A broadcasting transmitter as claimed in claim 7, wherein a Time Division Multiple Access (TDMA) modulator is incorporated instead of said SS modulator, wherein said TDMA modulator modulates said signals for said local area broadcasting based on a Time Division Multiple Access (TDMA) method in said second frequency bandwidth.

11. A broadcasting receiver for receiving a same program as a wide area broadcasting from a plurality of broadcasting stations and a different program as a local area broadcasting from one of said plurality of broadcasting stations by using one broadcasting channel, simultaneously, comprising:

a frequency divider for dividing broadcasting signals of said wide area broadcasting and said local area broadcasting transmitted through said broadcasting channel into signals on a first frequency bandwidth and a second frequency bandwidth;

an Orthogonal Frequency Division Multiplex (OFDM) demodulator for demodulating said signals on said first frequency bandwidth based on a OFDM demodulation method; and

a Spread Spectrum (SS) demodulator for demodulating said signals on said second frequency bandwidth by using a different spreading code allocated corresponding to each of said plurality of broadcasting stations based on a SS demodulation method.

12. A broadcasting receiver as claimed in claim 11, wherein a Frequency Division Multiple Access (FDMA) demodulator is incorporated instead of said SS demodulator, wherein said OFDM demodulator demodulates said signals for said local area broadcasting by using one of a plurality of sub-broadcasting frequency bandwidths obtained by dividing said second frequency bandwidth allocated for each of said plurality of broadcasting stations.

13. A broadcasting transmitter as claimed in claim 11, wherein a Time Division Multiple Access (TDMA) demodulator is incorporated instead of said SS demodulator, wherein said TDMA demodulator demodulates said signals for said local area broadcasting based on a Time Division Multiple Access (TDMA) method in said second frequency bandwidth.