Hierarchical OFDM system

Claim 2

A hierarchical quadrature frequency multiplex signal transmission system for transmitting multiple layers of hierarchical information data modulated using a plurality of hierarchically graded modulation forms with required C/N ratios different from each other, characterized in that the multiple layers of the hierarchical information data are constituted into a frame comprising a plurality of symbols of the information data, the symbols in a prescribed layer of the hierarchical information data having a particular grade modulation form are interleaved in both directions of the time axis and the frequency axis, and the plurality of hierarchically graded modulation forms are respectively associated with individually predetermined carriers, and wherein at least one of the modulation forms is differentially encoded.

Claim 3

A hierarchical quadrature frequency multiplex signal transmission system as claimed in claim 1, characterized in that the plurality of hierarchically graded modulation forms include a QPSK modulation, a 16QAM modulation and a 64QAM modulation.

Claim 4

A hierarchical quadrature frequency multiplex signal transmission system as claimed in claim 2, characterized in that the plurality of hierarchically graded modulation forms include a QPSK modulation, a 16QAM modulation and a 64QAM modulation, and wherein the QPSK modulation is differentially encoded.

Claim 5

A hierarchical quadrature frequency multiplex signal transmission apparatus comprising: means for producing a plurality of modulated signals in which multiple layers of hierarchical information data are associated with a plurality of hierarchically graded modulation forms respectively conveying required C/N ratios: means, in a frame constituted by symbols of the multiple layers of the hierarchical information data, for interleaving the symbols in a prescribed layer of the hierarchical information data associated with a particular grade modulation form in both directions of the time axis and the frequency axis; and means for performing an inverse Fourier transform on every symbol, by allocating a plurality of hierarchically graded modulation forms to respective predetermined carriers.

Claim 6

A hierarchical quadrature frequency multiplex signal transmission apparatus comprising: means for producing a plurality of modulated signals in which multiple layers of hierarchical information data are associated with a plurality of hierarchically graded modulation forms respectively conveying required C/N ratios: means, in a frame constituted by symbols of the multiple layers of the hierarchical information data, for Interleaving the symbols in a prescribed layer of the hierarchical information data associated with a particular grade modulation form in both directions of the time axis and the frequency axis; and means for performing an inverse Fourier transform on every symbol, by allocating a plurality of hierarchically graded modulation forms to respective predetermined carriers, and wherein at least one of the of the hierarchically graded modulation forms is differentially encoded.

Claim 7

An quadrature frequency multiplex signal transmission apparatus as claimed in claim 6, characterized in that the differential encoding is associated to the lowest grade hierarchical modulation form.

Claim 8

A hierarchical quadrature frequency multiplex signal receiving apparatus, comprising: means for receiving to demodulate signals transmitted by means of hierarchical quadrature frequency multiplex signal transmission system for transmitting multiple layers of hierarchical information data modulated using a plurality of hierarchically graded modulation forms with required C/N ratios different from each other, characterized in that the multiple layers of the hierarchical information data are constituted into a frame comprising a plurality of symbols of the information data, the symbols in a respective layer of the hierarchical information data having a particular grade modulation form are interleaved in both directions of the time axis and the frequency axis, and the plurality of hierarchically graded modulation forms are respectively associated with individually predetermined carriers; means for performing a Fourier transform for every symbols of the demodulated output; means for recovering carriers using the Fourier transform output of a particular carrier allocated to the lowest hierarchical modulation form among the plural modulation forms; means for coherently detecting signals associated with all of the hierarchically graded modulation forms using the recovered carriers; means for reconstructing the detected signals into a frame composed of a plurality of symbols; means for deinterleaving frame symbols in a prescribed layer of the hierarchical information data having a particular grade modulation form in both directions of the time axis and the frequency axis; and means for recovering a plurality of hierarchical information data from the respective differing modulation forms with required C/N ratios different from each other.

Claim 9

A hierarchical quadrature frequency multiplex signal receiving apparatus, comprising: means for receiving to demodulate signals transmitted by means of hierarchical quadrature frequency multiplex signal transmission system for transmitting multiple layers of hierarchical information data modulated using a plurality of hierarchically graded modulation forms with required C/N ratios different from each other, characterized in that the multiple layers of the hierarchical information data are constituted into a frame comprising a plurality of symbols of the information data, the symbols in a respective layer of the hierarchical information data having a particular grade modulation form are interleaved in both directions of the time axis and the frequency axis, and the plurality of hierarchically graded modulation forms are respectively associated with individually predetermined carriers; means for performing a Fourier transform for every symbols of the demodulated output; means for recovering carriers using the Fourier transform output of a particular carrier allocated to the lowest hierarchical modulation form among the plural modulation forms; means for reconstructing the detected signals into a frame composed of a plurality of symbols; means for coherently detecting signals associated with the hierarchically graded modulation forms other than the lowest grade modulation form using the recovered carriers; means for demodulating signals associated with the lowest grade modulation form by means of a differential detection; means for deinterleaving frame symbols in a prescribed layer of the hierarchical information data having a particular grade modulation form in both directions of the time axis and the frequency axis; and means for recovering a plurality of hierarchical information data from the respective differing modulation forms with required C/N ratios different from each other.

Claim 10

A hierarchical quadrature frequency multiplex signal transmission system, characterized in that in a frame plotted its time axis and frequency axis with symbols and carriers, respectively, a set of carrier regions associated with the lowest grade, an intermediate grade and the highest grade hierarchical modulation forms is repeatedly arranged in the frequency axis of the frame, as well as the carriers being allocated with a plurality of hierarchical information data, and the hierarchical information data in a prescribed layer associated with a particular grade modulation form are interleaved in both directions of the time axis and the frequency axis, and data associated with the lowest grade modulation form are differentially encoded.

Claim 11

A hierarchical quadrature frequency multiplex signal transmission system as claimed in claim 10, characterized in that the plurality of hierarchical information data are signals differentiated their degrees of importance in originated from different signal sources.

Claim 12

A hierarchical quadrature frequency multiplex signal transmission system as claimed in claim 10, characterized in that the plurality of hierarchical information data are signals differentiated their degrees of importance by hierarchically assorted the signals originated from a single signal source.