Ensemble modem structure for imperfect transmission media

Claim 3

A method according to claim 1 wherein said varying step includes the steps of: determining the equivalent noise component for every carrier frequency in the ensemble; determining the marginal power requirement to increase the complexity of the data element on each carrier from n information units to n + 1 information units, n being an integer between 0 and N; ordering the marginal powers of all the carriers in the ensemble in order of increasing power; assigning available power to the ordered marginal powers in order of increasing power; determining the value, MP(max) at which point the available power is exhausted; and allocating power and data to each carrier frequency where the power allocated is equal to the sum of all the marginal powers less than or equal to MP(max) for that carrier and the number of data units allocated is equal to the number of marginal powers for that carrier less than or equal to MP(max).

Claim 4

A method according to claim 1 or claim 2 where said step of ordering comprises the steps of: providing a table or arbitrary marginal power levels; and rounding the value of each determined marginal power level to one of the values of the table of arbitrary marginal power levels to decrease computational complexity.

Claim 6

A method according to claim 4 wherein: each modem (26,26′) has an input buffer (32,32′) for storing data to be transmitted: said invention further includes steps of operating said modems (26,26′) to compensate for frequency dependent phase delay, where the maximum estimated magnitude of the phase delay is T ph , to prevent intersymbol interference, to allocate control of the transmission link between modem A(26) and modem B(26′) and for initiating a sampling interval having a given time sample offset equal to the receiprocal of the sampling frequency, said further steps comprising: transmitting a symbol encoded on one of said carrier frequencies where said symbol is a predetermined time duration, T s ; retransmitting the first T PH seconds of said symbol to form a transmitted waveform of duration T E + T PH ; allocating control of the transmission link to modem A(26); determining the volume of data stored in the input buffer (32) of modem A(26); determining the number, K, of packets of data required to transmit the volume of data stored in the input buffer (32) of modem A(26); transmitting L packets of data from modem A(26) to modem B(26′) where L is equal to I A if K is less than I A , where L is equal to K if K is greater than or equal to I A , and where L is equal to N A if K is greater than N A so that the minimum number of packets transmitted is I A and the maximum is N A ; allocating control of the transmission link to modem B(26′); determining the volume of data in the input buffer (32′) of modem B(26′); determining the number, J, of packets of data required to transmit the volume of data stored in the input buffer (32′) of modem B (26′); transmitting M packets of data from modem B (26′) to modem A(26) where M is equal to I B if J is less than I B , where M is equal to J if J is greater than or equal to I B , and where L is equal to N B is J is greater than N B so that the minimum number of packers transmitted is I B and the maximum is N B ; where allocation of control between modem A(26) and B(26′) is dependent on the volume of data stored in the input buffers (32,32′) of modems A(26) and B(26′); generating an analog waveform at modem A(26) including first and second frequency components at f₁ and f₂; transmitting said waveform from modem A(26) to modem B(26′) at time T A ; adjusting the phases of said first and second frequency components so that their relative phase difference at time T A is equal to about 0°; detecting energy at frequency f₁ at modem B(26′) to determine the estimated time, T EST , that said waveform arrives at modem B(26′); determining the relative phase difference at modem B (26′) between said first and second frequency components at time T EST ; calculating the number of sampling time offsets, N I , required for the relative phase of said first and second carriers to change from 0 to said relative phase difference; and changing the magnitude of T EST by N I sampling intervals to obtain a precise timing reference, T₀.

Claim 7

A high speed modem (26) of the type for transmitting a signal on a communication medium (48) comprising: means (30) for receiving an input digital data stream and means (32) for storing said input digital data; means (34) for generating a modulated ensemble of carriers to encode said input digital data; means for measuring the signal loss and noise loss of the communication medium for each carrier; characterizes in that: each carrier has data elements of variable complexity encoded thereon and there is provided; means (128) for varying the complexity of the data element encoded on each carrier and the amount of power allocated to each carrier to compensate for the measured signal loss and noise level.

Claim 8

A high speed modem (26) of the type for transmitting a signal on a communication medium (48) comprising: means (30) for receiving an input digital data stream and means (32) for storing said input digital data; means (34) for generating a modulated ensemble of carriers to encode said input digital data; means for measuring the signal loss and noise loss of the communication medium for each carrier; characterizes in that: each carrier has data elements of variable complexity encoded thereon and there is provided; means (128) for varying the complexity of the data element encoded on each carrier and the amount of power allocated to each carrier to compensate for the measured signal loss and noise level.

Claim 9

A high speed modem (26) according to claim 6, wherein said varying means includes: means for determining the equivalent noise component for every carrier frequency in the ensemble; means for determing the marginal power requirement to increase the complexity of the data element on each carrier from n information units to n + 1 information units, n being an integer between 0 and N; means for ordering the marginal powers of all the carriers in the ensemble in order of increasing power; means for assigning available power to the ordered marginal powers in order of increasing power; means for determining the value, MP (max) at which point the available power is exhausted; and means allocating power and data to each carrier frequency where the power allocated is equal to the sum of all the marginal powers less than or equal to MP(max) for that carrier and the number of data units allocated is equal to the number of marginal powers for that carrier less than or equal to MP(max).

Claim 10

A high speed modem according to claim 7 where said means for ordering comprises: means for providing a table of arbitrary marginal power levels; and means for rounding the value of each determined marginal power level to one of the values of the table of arbitrary marginal power levels to decrease computational complexity.

Claim 11

A high speed modem according to any one of the preceding claims includes: a digital electronic processor (120); a digital electronic memory (133); and bus means (135) for coupling said processor and said memory.

Claim 12

A high speed modem according to any one of the preceding claims wherein an A and B modem (26,26′) are connected by a communication medium (48) and the means for determining equivalent noise comprises: means for establishing a communication link between said A and B modems (26,26′); means for accumulating line noise data a no transmission time interval at said A and B modems (26,26′); means for transmitting a first ensemble of frequency carriers from said A modem (26) to said B modem (26′) where the amplitude of each carrier has a predetermined value; means for receiving said first ensemble at said B modem (26′); means for measuring the amplitude of each carrier received at said B modem (26′); means for comparing the measured amplitudes at said B modem (26′) with said predetermined amplitudes to determine signal loss at each carrier frequency; means for determining the value of the component, in dB, at each carrier frequency of the accumulated noise; and means for adding the signal loss at each carrier frequency to the noise component at each carrier frequency to determine noise.