Capacity allocation for OFDM

Claim 2

A method according to claim 1, characterized in that in said communication network, said data elements are provided by a plurality of services, said predetermined carrier criterion being the sensitivity of a said carrier for occasional noise increase, and said predetermined data criterion being the service dependent requirements for protection against said occasional noise increase.

Claim 3

A method according to claim 2, characterized in that said occasional noise increase is due to burst errors on connections in said communication network.

Claim 4

A method according to claim 2, characterized in that said occasional noise increase is due to clipping of signals transmitted in said communication network.

Claim 5

A method according to claim 2, characterized in that said sensitivity of a said carrier for said occasional noise increase is equal to a differential d(SNRdB)/d(No), wherein SNRdB represents the signal noise ratio in decibels measured on said carrier and wherein No represents the noise power measured on said carrier, said differential representing a variation of said signal noise ratio SNRdB at a variation of said noise power No and being proportional to 1/No.

Claim 6

A method according to claim 2, characterized in that said sensitivity of a said carrier for said occasional noise increase is equal to a differential d(BER)/d(No), wherein BER represents the bit error rate measured for said carrier and wherein No represents the noise power measured on said carrier, said differential representing a variation of said bit error rate BER at a variation of said noise power No.

Claim 7

A method according to claim 2, characterized in that said sensitivity of a said carrier for said occasional noise increase is obtained from a spectrum for impulsive noise.

Claim 8

A method according to claim 1, characterized in that N-1 of said carriers are mixed carriers, each being shared between two neighbouring ones of said subsets of carriers and allowed therefore to be allocated said data elements classified in two of said groups of data elements associated with one of said two subsets of carriers respectively.

Claim 9

A method according to claim 1, characterized in that for each carrier an associated signal noise ratio margin is minimized to thereby eliminate the possibility to reduce overall power transmission by removing a data element allocated to a said carrier from said carrier to another said carrier, said associated signal noise ratio margin for each said carrier being equal to SNR-SNRR wherein SNR represents the signal noise ratio measured for said carrier and wherein SNRR represents the required signal noise ratio allowing to modulate on said carrier the number of data elements allocated thereto, SNRR being obtained from a said 'required SNR per data element'-table.

Claim 10

A method according to claim 1, characterized in that, when said carriers are fictively arranged in decreasing or increasing order of signal noise ratio measured thereon, no intermediate carriers are left unoccupied, an intermediate carrier being a carrier between a first and last carrier in a sequence of carriers obtained by fictively arranging said carriers in decreasing or increasing order of said signal noise ratio.

Claim 11

A method according to claim 1, characterized in that said communication network is an Asymmetric Digital Subscriber Loop (ADSL) access network wherein said data elements are Discrete Multi Tone (DMT) modulated on a said set of carriers having equidistant frequencies.

Claim 12

A method according to claim 10, characterized in that no one bit constellations occur.

Claim 13

A mapping unit (MAP) for allocating data elements to a set of carriers for transmission thereof in a communication network, said mapping unit (MAP) including an SNR memory (SNRM) provided to store for each carrier of said set of carriers a signal noise ratio value, a table memory (TM) provided to store a 'required SNR per data element'-table defining the required signal noise ratio per data element allocated to a said carrier, and a processor (PROC) to a first input (I1) of which said data elements are applied, and to second (I2) and third (I3) inputs of which, outputs of said SNR memory (SNRM) and said table memory (TM) are connected respectively, said processor (PROC) being adapted to combine for each said carrier, said signal noise ratio value with information in said 'required SNR per data element'-table to decide which number of said data elements to allocate to each said carrier, characterized in that said table memory (TM) is subdivided into N table memories (TM1 ... TMN) being associated one by one with N subsets of carriers and provided thus to store a 'required SNR per data element'-table defining the required signal noise ratio per data element allocated to a carrier of said associated subset of carriers, and furthermore that said processor (PROC) is adapted to divide said set of carriers, according to a predetermined carrier criterion, into said N subsets of carriers constituting an adaptable partition of said set of carriers, to classify said data elements, according to a predetermined data criterion, into N groups of data elements, said predetermined carrier criterion and said predetermined data criterion having a relation on the basis of which each of said N groups of data elements is associated with a said subset of carriers, and to allocate said data elements to said carriers in such a way that said data elements classified in a said group of data elements are allocated to said carriers forming part of said subset associated with said group.

Claim 14

A modulator (MOD) for modulation of data elements applied to an input (MI1) thereof on a set of carriers for transmission thereof in a communication network coupled to an output (MO) thereof, said modulator (MOD) including between said input (MI1) and said output (MO) a cascade connection of a mapping unit (MAP), a transformation unit (IFFT, CPA), a parallel to serial converter (PSC) and a digital to analog converter (DAC), said mapping unit (MAP) being provided to allocate said data elements to said set of carriers and to thereby generate a frequency domain parallel sequence of data, said transformation unit (IFFT, CPA) being included to transform said frequency domain parallel sequence of data applied to its input and to thereby generate a time domain parallel sequence of data, said parallel to serial converter (PSC) being adapted to convert said time domain parallel sequence of data into a serial sequence of data which is applied to said digital to analog converter included to transform said serial sequence of data into an analog signal and to supply said analog signal to said output (MO) of said modulator (MOD), said mapping unit (MAP) including an SNR memory (SNRM) provided to store for each carrier of said set of carriers a signal noise ratio value, a table memory (TM) provided to store a 'required SNR per data element'-table defining the required signal noise ratio per data element allocated to a said carrier, and a processor (PROC) to a first input (I1) of which said data elements are applied, and to second (I2) and third (I3) inputs of which, outputs of said SNR memory (SNRM) and said table memory (TM) are connected respectively, said processor (PROC) being adapted to combine for each said carrier, said signal noise ratio value with information in said 'required SNR per data element'-table to decide which number of said data elements to allocate to each said carrier, characterized in that said table memory (TM) is subdivided into N table memories (TM1 ... TMN) being associated one by one with N subsets of carriers and provided thus to store a 'required SNR per data element'-table defining the required signal noise ratio per data element allocated to a carrier of said associated subset of carriers, and furthermore that said processor (PROC) is adapted to divide said set of carriers, according to a predetermined carrier criterion, into said N subsets of carriers constituting an adaptable partition of said set of carriers, to classify said data elements, according to a predetermined data criterion, into N groups of data elements, said predetermined carrier criterion and said predetermined data criterion having a relation on the basis of which each of said N groups of data elements is associated with a said subset of carriers, and to allocate said data elements to said carriers in such a way that said data elements classified in a said group of data elements are allocated to said carriers forming part of said subset associated with said group.