Communication system

• US 6,256,357 B1
• Filed: 08/24/1999
• Issued: 07/03/2001
• Est. Priority Date: 03/26/1992
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Oshima, Mitsuaki
• Primary Examiner(s): Le, Amanda T.
• Application Number:
  US09/379,746
• Time in Patent Office: 679 Days
• Field of Search: 375/261, 375/279, 375/280, 375/284, 375/298, 375/308, 375/324, 375/329, 375/332, 348/555, 348/426, 348/432, 348/433, 348/726, 329/304, 332/103
• US Class Current: 375/261
• CPC Class Codes: H03M 13/23 using convolutional codes, e.g. unit memory codes
• 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 13/356 Unequal error protection [UEP]
• 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 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0058 Block-coded modulation
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/006 Trellis-coded modulation
• CPC Class Codes: H04L 1/0065 Serial concatenated codes
• CPC Class Codes: H04L 1/007 Unequal error protection for format H04L1/0078; for codes per se H03M13/35
• CPC Class Codes: H04L 2001/0098 Unequal error protection
• 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 27/2627 : Modulators
• CPC Class Codes: H04L 27/2649 : Demodulators
• CPC Class Codes: H04L 27/3405 : Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
• CPC Class Codes: H04L 27/3488 : Multiresolution systems
• CPC Class Codes: H04L 27/36 : Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/38 : Demodulator circuits; Receiver circuits
• CPC Class Codes: H04L 27/3854 : using a non - coherent carrier, including systems with baseband correction for phase or frequency offset
• CPC Class Codes: H04L 5/0007 : the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0046 : Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04N 11/26 : involving two-channel transmission
• CPC Class Codes: H04N 19/30 : using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• 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 21/2383 : 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 21/426 : Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• 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 21/4383 : Accessing a communication channel
• CPC Class Codes: H04N 21/440272 : for performing aspect ratio conversion
• 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 5/455 : Demodulation-circuits
• 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. 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 stream 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.

Claims

1. A signal transmission apparatus for transmitting a first data stream and a second data stream, said signal transmission apparatus comprising:

a modulator operable to assign each data stream to a respective constellation in a signal space to produce modulated signals such that the number of signal points of the first data stream assigned in the signal space is different from the number of signal points of the second data stream assigned in the signal space, wherein the first data stream has data for demodulation including information representing the number of signal points of the second data stream assigned in the signal space;

an inverse Fast Fourier transformer operable to convert the modulated signals into a signal on a time axis to produce a transmission signal; and

a transmitter operable to transmit the transmission signal.

2. A signal receiving apparatus comprising:

a receiver operable to receive a received signal having information of a first data stream and a second data stream, wherein the number of signal points of the first data stream assigned in a signal space is different from the number of signal points of the second data stream assigned in a signal space, and the first data stream has data for demodulation including information representing the number of signal points of the second data stream assigned in the signal space;

a Fast Fourier transformer operable to convert the received signal into a signal on a frequency axis; and

a demodulator operable to demodulate the signal on the frequency axis from said Fast Fourier transformer to produce the first and second data streams and to demodulate the second data stream according to the data for demodulation in the first data stream.

3. A signal transmission system for transmitting and receiving a first data stream and a second data stream, said signal transmission system comprising:

a signal transmission apparatus for transmitting the first and second data streams, said signal transmission apparatus including a modulator operable to assign each data stream to a respective constellation in a signal space to produce modulated signals such that the number of signal points of the first data stream assigned in the signal space is different from the number of signal points of the second data stream assigned in the signal space, wherein the first data stream has data for demodulation including information representing the number of signal points of the second data stream assigned in the signal space, an inverse Fast Fourier transformer operable to convert the modulated signals into a signal on a time axis to produce a transmission signal, and a transmitter operable to transmit the transmission signal; and

a signal receiving apparatus including a receiver operable to receive a received signal having information of the first and second data streams, a Fast Fourier transformer operable to convert the received signal into a signal on a frequency axis, and a demodulator operable to demodulate the signal on the frequency axis from said Fast Fourier transformer to produce the first and second data streams and to demodulate the second data stream according to the data for demodulation in the first data stream.

4. A signal transmission method for transmitting a first data stream and a second data stream, said signal transmission method comprising:

assigning each data stream to a respective constellation in a signal space to produce modulated signals such that the number of signal points of the first data stream assigned in the signal space is different from the number of signal points of the second data stream assigned in the signal space, wherein the first data stream has data for demodulation including information representing the number of signal points of the second data stream assigned in the signal space;

inverse Fast Fourier transforming the modulated signals so as to convert the modulated signals into a signal on a time axis to produce a transmission signal; and

transmitting the transmission signal.

5. A signal receiving method comprising:

receiving a received signal having information of a first data stream and a second data stream wherein the number of signal points of the first data stream assigned in a signal space is different from the number of signal points of the second data stream assigned in the signal space, and the first data stream has data for demodulation including information representing the number of signal points of the second data stream assigned in the signal space;

Fast Fourier transforming the received signal so as to convert the received signal into a signal on a frequency axis; and

demodulating the signal on the frequency axis from said Fast Fourier transforming to produce the first and second data streams and demodulating the second data stream according to the data for demodulation in the first data stream.