Communication system

• US RE41,003 E1
• Filed: 12/20/2000
• Issued: 11/24/2009
• Est. Priority Date: 03/26/1992
• Status: Expired due to Term

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Oshima, Mitsuaki
• Primary Examiner(s): Chevalier, Robert
• Application Number:
  US09/740,068
• Time in Patent Office: 3,261 Days
• Field of Search: 386/46, 386/1, 386/36, 386/37, 386/92, 386/123, 348/723, 348/729, 348/608, 348/725, 348/737, 348/17, 348/22, 348/21, 348/24, 348/636, 725/90, 725/95
• US Class Current: 386/263
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 2220/213 Read-only discs
• CPC Class Codes: G11B 2220/2545 CDs
• CPC Class Codes: G11B 27/034 on discs G11B27/036, G11B27/038 take precedence
• CPC Class Codes: G11B 27/105 of operating discs
• CPC Class Codes: H03M 13/253 with concatenated codes
• CPC Class Codes: H03M 13/256 with trellis coding, e.g. with convolutional codes and TCM
• CPC Class Codes: H03M 13/2936 comprising an outer Reed-Solomon code and an inner convolutional code
• CPC Class Codes: H03M 13/35 Unequal or adaptive error protection, e.g. by providing a different level of protection according to significance of source information or by adapting the coding according to the change of transmission channel characteristics
• CPC Class Codes: H03M 13/6538 ATSC VBS systems
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/006 Trellis-coded modulation
• CPC Class Codes: H04L 2027/0036 using a recovered symbol clock
• CPC Class Codes: H04L 2027/0053 Closed loops
• CPC Class Codes: H04L 2027/0067 Phase error detectors
• CPC Class Codes: H04L 27/02 Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation H04L27/32 takes precedence
• CPC Class Codes: H04L 27/04 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/183 Multiresolution systems
• CPC Class Codes: H04L 27/2602 : Signal structure
• CPC Class Codes: H04L 27/2604 : Multiresolution systems by means of multiresolution subcarriers H04L27/183, H04L27/3488
• CPC Class Codes: H04L 27/2605 : Symbol extensions, e.g. Zero Tail, Unique Word [UW]
• CPC Class Codes: H04L 27/2608 : Allocation of payload
• CPC Class Codes: H04L 27/34 : Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
• CPC Class Codes: H04L 27/3416 : in which the information is carried by both the individual signal points and the subset to which the individual points belong, e.g. using coset coding, lattice coding, or related schemes
• CPC Class Codes: H04L 27/3488 : Multiresolution systems
• CPC Class Codes: H04L 27/3854 : using a non - coherent carrier, including systems with baseband correction for phase or frequency offset
• CPC Class Codes: H04N 19/37 : with arrangements for assigning different transmission priorities to video input data or to video coded data
• CPC Class Codes: H04N 19/60 : using transform coding
• CPC Class Codes: H04N 19/63 : using sub-band based transform, e.g. wavelets
• CPC Class Codes: H04N 21/234327 : by decomposing into layers, e.g. base layer and one or more enhancement layers
• CPC Class Codes: H04N 21/2365 : Multiplexing of several video streams
• CPC Class Codes: H04N 21/2383 : Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/2385 : Channel allocation H04N21/266 takes precedence; Bandwidth allocation H04N21/24 takes precedence ; allocation of channels according to the instantaneous demands of the users in time-division multiplex systems H04J3/1682; admission control, resource allocation in open networks H04L12/5692; arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896; negotiating bandwidth in wireless networks H04W28/16
• CPC Class Codes: H04N 21/4347 : Demultiplexing of several video streams
• CPC Class Codes: H04N 21/4382 : Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/440227 : by decomposing into layers, e.g. base layer and one or more enhancement layers
• CPC Class Codes: H04N 21/44209 : Monitoring of downstream path of the transmission network originating from a server, e.g. bandwidth variations of a wireless network arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896
• CPC Class Codes: H04N 21/4425 : Monitoring of client processing errors or hardware failure
• CPC Class Codes: H04N 21/4621 : Controlling the complexity of the content stream or additional data, e.g. lowering the resolution or bit-rate of the video stream for a mobile client with a small screen arrangements for using the results of monitoring on user's side in broadcast systems H04H60/65; flow control in packet networks H04L47/10
• CPC Class Codes: H04N 21/631 : Multimode Transmission, e.g. transmitting basic layers and enhancement layers of the content over different transmission paths or transmitting with different error corrections, different keys or with different transmission protocols
• CPC Class Codes: H04N 21/64792 : Controlling the complexity of the content stream, e.g. by dropping packets intermediate media network packet handling H04L65/765; proxy provisioning conversion or adaptation for reducing the amount or size of exchanged application data H04L67/5651; negotiation of resources in wireless networks H04W28/16
• CPC Class Codes: H04N 5/4401 : for the reception of a digital modulated video signal
• CPC Class Codes: H04N 5/455 : Demodulation-circuits
• CPC Class Codes: H04N 5/782 : on tape
• CPC Class Codes: H04N 7/015 : High-definition television systems
• CPC Class Codes: H04N 7/24 : Systems for the transmission of television signals using pulse code modulation H04N21/00 takes precedence

Abstract

At the transmitter side, carrier waves are modulated according to an input signal for producing relevant signal points in a signal space diagram. The input signal is divided into, two, first and second, data streams. The signal points are divided into signal point groups to which data of the first data stream are assigned. Also, data of the second data stream are assigned to the signal points of each signal point group. A difference in the transmission error rate between first and second data streams is developed by shifting the signal points to other positions in the space diagram expressed at least in the polar coordinate system. At the receiver side, the first and/or second data streams can be reconstructed from a received signal. In TV broadcast service, a TV signal is divided by a transmitter into, low and high, frequency band components which are designated as a first and a second data streams respectively. Upon receiving the TV signal, a receiver can reproduce only the low frequency band component or both the low and high frequency band components, depending on its capability. Furthermore, a communication system based on an OFDM system is utilized for data transmission of a plurality of subchannels, wherein the subchannels are differentiated by changing the length of a guard time slot or a carrier wave interval of a symbol transmission time slot, or changing the transmission electric power of the carrier.

Claims

1. A digital TV receiver comprising:

a receiving section for receiving a PSK (Phase Shift Key) modulation signal comprising a plurality of signal points disposed on specific phases of a given constellation in a signal space diagram;

a demodulator for demodulating the received signal from said receiving section into a digital signal;

an error correcting section for error correcting a demodulation signal from said demodulator; and

an image expander for expanding an error-corrected signal from said error correcting section to a video signal, thereby outputting a video signal,

wherein said demodulator demodulates the receiving signal as first and second PSK signals, said first PSK signal representing a first data stream to be reproduced, said first PSK signal comprising n-value signal points, said second PSK signal representing both said first data steam and a second data stream to be reproduced, said second PSK signal comprising m-value signal points, where m is an integer larger than n,

wherein the m-value signal points of said second PSK signal are divisible into n groups of signal points which are distinguishable from one another in the signal space, and said demodulator distinguishes said n groups of signal points from one another as the n-value signal points of said first PSK signal by demodulating the received signal as said first PSK signal, and wherein high priority information is demodulated at least in said first data stream.

2. The digital TV receiver in accordance with claim 1, wherein said demodulator demodulates information relating to a low-resolution component of the video signal from said first data stream and demodulates information relating to a high-resolution component of the video signal from said second data stream.

3. The digital TV receiver in accordance with claim 1, comprising means for stopping output of said second data stream when an error rate of the received signal is high.

4. The digital TV receiver in accordance with claim 1, wherein said demodulator comprises first means for demodulating the received signal as a QPSK signal to reproduce the first data stream and second means for demodulating the received signal as a 8PSK signal to reproduce both of the first data stream and the second data stream.

5. A signal TV receiver comprising:

a receiving section for receiving a PSK (Phase Shift Key) modulation signal comprising m-value signal points disposed on specific phases of a given constellation in a signal space diagram and representing a first data stream and a second data stream to be reproduced;

a demodulator for demodulating the said PSK modulation signal from said receiving section into a digital signal;

an error correcting section for error correcting a demodulation signal from said demodulator; and

an image expander for expanding an error-corrected signal from said error correcting section to a video signal,

wherein said demodulator includes means for demodulating said PSK signal comprising m-value signal points as another PSK signal,

said another PSK signal comprising n-value signal points and representing only said first data stream, where n is an integer smaller than m, and wherein

high priority information is demodulated at least in said first data stream.

6. A signal transmission apparatus comprising:

a modulator operable to assign and interleave a data stream of a layer A and a data stream of a layer B to a respective constellation in a signal space to produce a modulated signal of the layer A and a modulated signal of the layer B;

an inverse fast Fourier transformer operable to convert the modulated signal of the layer A into a transmission signal on a time axis in the layer A and to convert the modulated signal of the layer B into a transmission signal on a time axis in the layer B, wherein each transmission signal comprises an effective symbol signal and a guard interval signal, and a period of the guard interval signal in the layer A is larger than the period of the guard interval signal in the layer B; and

a transmitter operable to transmit the transmission signals.

7. A signal receiving apparatus for use in receiving a modulation signal in a layer A and a modulation signal in a layer B, wherein the modulation signals each include a guard interval signal, said apparatus comprising:

a fast-Fourier transformer operable to convert the modulation signal in the layer A into a converted signal on a frequency axis in the layer A and to convert the modulation signal in the layer B into a converted signal on a frequency axis in the layer B; and

a demodulator operable to de-interleave the converted signals, demodulate the converted signal in the layer A into a data stream of the layer A and to demodulate the converted signal in the layer B into a data stream of the layer B;

wherein a period of the guard interval signal in the layer A is larger than a period of the guard interval signal in the layer B.

8. A signal transmission system comprising:

a signal transmission apparatus including

a modulator operable to assign and interleave a data stream of a layer A and a data stream of a layer B to a respective constellation in a signal space to produce a modulated signal of the layer A and a modulated signal of the layer B,

an inverse fast Fourier transformer operable to convert the modulated signal of the layer A into a transmission signal on a time axis in the layer A and to convert the modulated signal of the layer B into a transmission signal on a time axis in the layer B, wherein each transmission signal comprises an effective symbol signal and a guard interval signal, and a period of the guard interval signal in the layer A is larger than a period of the guard interval signal in the layer B, and

a transmitter operable to transmit the transmission signals; and

a signal receiving apparatus including

a receiver operable to receive the transmission signal in the layer A and the transmission signal in the layer B,

a fast-Fourier transformer operable to convert the transmission signal in the layer A into a converted signal on a frequency axis in the layer A and to convert the transmission signal in the layer B into a converted signal on a frequency axis in the layer B, and

a demodulator operable to de-interleave the transmission signals, demodulate the converted signal in the layer A into a data stream of the layer A and to demodulate the converted signal in the layer B into a data stream of the layer B.

9. A signal transmission method comprising:

assigning and interleaving a data stream of a layer A and a data stream of a layer B to a respective constellation in a signal space to produce a modulated signal of the layer A and a modulated signal of the layer B;

inverse fast Fourier transforming the modulated signal of the layer A into a transmission signal on a time axis in the layer A and inverse fast Fourier transforming the modulated signal of the layer B into a transmission signal on a time axis in the layer B, wherein each transmission signal comprises an effective symbol signal and a guard interval signal, and a period of the guard interval signal in the layer A is larger than a period of the guard interval signal in the layer B; and

transmitting the transmission signals.

10. A signal receiving method for use in receiving a modulation signal in a layer A and a modulation signal in a layer B, wherein the modulation signals each include a guard interval signal, and a period of the guard interval signal in the layer A is larger than a period of the guard interval signal in the layer B, said method comprising:

fast-Fourier transforming the modulation signal in the layer A into a converted signal on a frequency axis in the layer A and fast-Fourier transforming the modulation signal in the layer B into a converted signal on a frequency axis in the layer B; and

de-interleaving the modulation signals, demodulating the converted signal in the layer A into a data stream of the layer A and demodulating the converted signal in the layer B into a data stream of the layer B.