Communication system

• US 6,728,467 B2
• Filed: 12/21/2000
• Issued: 04/27/2004
• Est. Priority Date: 03/26/1992
• Status: Expired due to Fees

• 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): Chevalier, Robert
• Application Number:
  US09/741,429
• Publication Number:
  US 20020097336A1
• Time in Patent Office: 1,223 Days
• Field of Search: 386/46-83, 386/95, 386/92, 386/36, 375/261, 375/279, 375/280, 375/295, 375/298, 375/308, 375/324, 375/321, 375/329, 375/332, 348/555, 348/432.1, 348/433.1, 348/726, 348/723, 329/304, 332/103
• US Class Current: 375/261
• CPC Class Codes: H03M 13/256 with trellis coding, e.g. with convolutional codes and TCM
• 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: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0042 Encoding specially adapted to other signal generation operation, e.g. in order to reduce transmit distortions, jitter, or to improve signal shape H04L1/0067 takes precedence
• CPC Class Codes: H04L 1/0047 Decoding adapted to other signal detection operation in conjunction with sequence estimation or equalization H04L25/03286
• 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 1/006 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 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 27/34 Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
• 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: H04N 19/36 : Scalability techniques involving formatting the layers as a function of picture distortion after decoding, e.g. signal-to-noise [SNR] scalability
• 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 21/426 : Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• 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 21/4621 : 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 21/64792 : 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 5/455 : Demodulation-circuits
• CPC Class Codes: H04N 5/46 : for receiving on more than one standard at will deflecting circuits of multi-standard receivers H04N3/27
• 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 signal transmission apparatus comprising:

a modulator operable to assign a first data stream to a respective constellation in a vector space diagram to produce a modulated signal,

a converter operable to convert the modulated signal into a converted signal having an effective symbol part and a guard interval, according to Orthogonal Frequency Division Multiplexing, and

a transmitter operable to transmit the converted signal,

wherein the effective symbol part is selected to have a predetermined time period.

7. A signal transmission apparatus according to claim 1, wherein the converter is an inverse Fast Fourier Transformer.

2. A signal receiving apparatus comprising:

a converter operable to convert a received signal, having an effective symbol part and a guard interval, into a converted signal according to Orthogonal Frequency Division Multiplexing, the effective symbol part being selected to have a predetermined time period,

the received signal having information of a data stream, wherein the data stream is assigned to a respective constellation in a vector space diagram, and

a demodulator operable to demodulate the converted signal to produce the data stream.

8. A signal receiving apparatus according to claim 2, wherein the converter is a Fast Fourier Transformer.

3. A signal transmission system comprising:

a signal transmission apparatus comprising;

a modulator operable to assign a data stream to a respective constellation in a vector space diagram to produce a modulated signal,

a frequency-time converter operable to frequency-time convert the modulated signal into a frequency-time converted signal, having an effective symbol part and a guard interval, according to Orthogonal Frequency Division Multiplexing, and

a transmitter operable to transmit the frequency-time converted signal; and

a signal receiving apparatus comprising;

a time-frequency converter operable to time-frequency convert the frequency-time converted signal into a time-frequency converted signal according to Orthogonal Frequency Division Multiplexing, and

a demodulator operable to demodulate the time-frequency converted signal to produce the data stream,

wherein the effective symbol part is selected to have a predetermined time period.

9. A signal transmission system according to claim 3, wherein the frequency-time converter is an inverse Fast Fourier Transformer, and the time-frequency converter is a Fast Fourier Transformer.

4. A signal transmission method comprising:

assigning a data stream to a respective constellation in a vector space diagram to produce a modulated signal,

converting the modulated signal into a converted signal having an effective symbol part and a guard interval, according to Orthogonal Frequency Division Multiplexing, and

transmitting the converted signal,

wherein the effective symbol part is selected to have a predetermined time period.

5. A signal receiving method comprising:

converting a received signal, having an effective symbol part and a guard interval, into a converted signal according to Orthogonal Frequency Division Multiplexing, the effective symbol part being selected to have a predetermined time period,

the received signal having information of a data stream, wherein the data stream is assigned to a respective constellation in a vector space diagram, and

demodulating the converted signal to produce the data stream.

6. A signal transmitting and receiving method comprising:

assigning a data stream to a respective constellation in a vector space diagram to produce a modulated signal,

frequency-time converting the modulated signal into a frequency-time converted signal having an effective symbol part and a guard interval, according to Orthogonal Frequency Division Multiplexing,

transmitting the frequency-time converted signal,

time-frequency converting the frequency-time converted signal into a time-frequency converted signal according to Orthogonal Frequency Division Multiplexing, and

demodulating the time-frequency converted signal to produce the data stream,

wherein the effective symbol part is selected to have a predetermined time period.