Abstract: Methods, apparatus and systems for implementing an algorithm for N-symbol noncoherent processing of M-ary DPSK signals in a pilotless, wireless system is provided. The algorithm is carried out with (N?1) recurrent steps (iterations) plus a decision step. Each iterative step includes simple trigonometrical transformation of quadrature components of the current symbol and summation of the transforms with results of the previous step. A final N-symbol decision regarding the current transmitted symbol corresponds to the vector of maximum length, calculated after the (N?1)-th step of the iterative procedure. The general algorithm is optionally implemented with one or more intersymbol processors, one or more memory blocks for saving results of the intersymbol processors, and a decision block. In addition, shift registers for quadrature components of the received signal may be utilized.

Abstract: Systems, methods and apparatus are provided for demapping a received wireless signal. The wireless signal includes signal-bearing data without accompanying pilot signals, and demapping is accomplished by extracting information from the signal-bearing data by reducing and averaging differential quadrature components or quadrature components of the received signal. Two embodiments are provided for the demapping procedure within a phase tracking loop.

Abstract: Systems, methods and apparatus are provided for equalizing a received multicarrier wireless telecommunications data signal. The wireless signal includes data without accompanying pilot signals, and equalization is accomplished by extracting information from the data, by processing the information in order to obtain equalization indications, and by equalizing the multicarrier wireless telecommunications data signal by modifying indications of the wireless telecommunications data signal using the equalization indications.

Abstract: Methods, apparatus, and systems for mode assignment and mode adaptation to channel conditions are provided which are based on estimations of real signal-to-noise ratios (SNR) for each frequency carrier bearing information during a data transmission session. The invention utilizes two principal procedures: signal-to-noise ratio (SNR) estimation, and a corresponding mode assignment. SNR estimation is obtained by an averaging of squared Euclidean distances between normalized received signals and reference signals corresponding to either current hard decisions from the output of a demodulator or soft decisions provided by a decoder, for each frequency carrier bearing random information. Using the SNR estimations, various algorithms for determining mode assignment are provided.

Abstract: A modem includes an LDPC encoder which utilizes a deterministic H-matrix, optionally via a generation matrix, to generate redundant parity bits for a bit block. Ones are placed into the H-matrix in a completely diagonal manner with diagonals subdivided into sets of diagonals. The first diagonal in each set i begins with coordinates H(1,k), where k=(1+(i*Mj)). The remaining diagonals in the sets are offset from the first diagonals so that the column distances between any two pairs of diagonals is unique. In another embodiment, the H-matrix is determined by assigning “1s” in a first column, and then assigning “1s” of subsequent columns deterministically by causing each “1” in a previous ancestor column to generate a “1” in the next descendant column based on the rule that a descendant is placed one position below an ancestor except where rectangles would be generated. Interrupted descending diagonals are generated.

Abstract: Methods, apparatus and systems for implementing an algorithm for N-symbol noncoherent processing of M-ary DPSK signals in a pilotless, wireless system is provided. The algorithm is carried out with (N?1) recurrent steps (iterations) plus a decision step. Each iterative step includes simple trigonometrical transformation of quadrature components of the current symbol and summation of the transforms with results of the previous step. A final N-symbol decision regarding the current transmitted symbol corresponds to the vector of maximum length, calculated after the (N?1)-th step of the iterative procedure. The general algorithm is optionally implemented with one or more intersymbol processors, one or more memory blocks for saving results of the intersymbol processors, and a decision block. In addition, shift registers for quadrature components of the received signal may be utilized.

Abstract: Apparatus, methods and systems for frequency offset compensation in multipoint-to-point orthogonal frequency division multiplexing (OFDM) systems are provided. In the hub, frequency offset estimates are made in the frequency domain for each group of carriers of the OFDM system. The hub then transmits indications (parameters) of the frequency offset for each group of carriers to the nodes. Frequency offset compensation is then accomplished in each node, preferably in the time domain.

Abstract: An easily implementable soft decision decoding (SDD) metric is provided for telecommunications systems and apparatus. The SDD metric is based on weighted average distances or weighted minimum distances between scaled received signals and all reference signals related to the corresponding binary symbol. An important property of the SDD metric of the invention is that the distance weight is completely defined by the received signal scaling factor which is readily available as a result of conventional frequency domain equalization procedures. The invention is particularly advantageous in wireless systems having variable parameters such as wireless OFDM systems with selective fading.

Abstract: Systems, methods and apparatus are provided for equalizing a received multicarrier wireless telecommunications data signal. The wireless signal includes data without accompanying pilot signals, and equalization is accomplished by extracting information from the data, by processing the information in order to obtain equalization indications, and by equalizing the multicarrier wireless telecommunications data signal by modifying indications of the wireless telecommunications data signal using the equalization indications.

Abstract: Systems, methods and apparatus are provided for demapping a received wireless signal. The wireless signal includes signal-bearing data without accompanying pilot signals, and demapping is accomplished by extracting information from the signal-bearing data by reducing and averaging differential quadrature components or quadrature components of the received signal. Two embodiments are provided for the demapping procedure within a phase tracking loop.

Abstract: Methods, apparatus, and systems for mode assignment and mode adaptation to channel conditions are provided which are based on estimations of real signal-to-noise ratios (SNR) for each frequency carrier bearing information during a data transmission session. The invention utilizes two principal procedures: signal-to-noise ratio (SNR) estimation, and a corresponding mode assignment. SNR estimation is obtained by an averaging of squared Euclidean distances between normalized received signals and reference signals corresponding to either current hard decisions from the output of a demodulator or soft decisions provided by a decoder, for each frequency carrier bearing random information. Using the SNR estimations, various algorithms for determining mode assignment are provided.

Abstract: A method for determining the encoding law of an incoming signal in a network which possibly contains an A-&mgr; or &mgr;-A conversion includes obtaining digital impairment learning (DIL) probing data, generating an ordered table of levels therefrom, using the table to find two functions, and using a logical analysis of the functions to determine the encoding law of the signal. A first function is a maximum from the values DL(i) and the threshold Th1 which are less than T(i), with T(i)=a +bi, and DL(i)=L(i+16)−2L(i) with L(i) being the DIL signal corresponding to the transmitted Ucode=i.

Abstract: Handshake information for xDSL services is transmitted utilizing a spread spectrum modulated system where a plurality (n) of carrier tones (n>2) are summed and utilized as a spread spectrum carrier (SSC), and data is modulated onto the carrier (at all utilized frequencies). Preferably, phase shift keying (PSK) modulation or a variation thereof is used as the encoding/modulation technique.

Abstract: An easily implementable soft decision decoding (SDD) metric is provided for telecommunications systems and apparatus. The SDD metric is based on weighted average distances or weighted minimum distances between scaled received signals and all reference signals related to the corresponding binary symbol. An important property of the SDD metric of the invention is that the distance weight is completely defined by the received signal scaling factor which is readily available as a result of conventional frequency domain equalization procedures. The invention is particularly advantageous in wireless systems having variable parameters such as wireless OFDM systems with selective fading.

Abstract: Data carrier duplication (DCD) is used to implement power control in multipoint-to-point OFDM systems. In DCD, data on several carriers (i.e., frequencies) is utilized in order to increase the power of a channel. Data carrier duplication not only provides power control capabilities, but it also mitigates selective fading problems. In a “closed loop power control” (CLPC) scheme, a hub is provided with certain intelligence which allows it to provide optimal distribution of carriers among nodes. In an “open loop power control” (OLPC) scheme, the nodes are provided with more intelligence to allow them to determine the number of additional carriers they require for transmitting data.

Abstract: A method for determining the encoding law of an incoming signal in a network which possibly contains an A-&mgr; or &mgr;-A conversion includes obtaining digital impairment learning (DIL) probing data, generating an ordered table of levels therefrom, using the table to find two functions, and using a logical analysis of the functions to determine the encoding law of the signal. A first function is a maximum from the values DL(i) and the threshold Th1 which are less than T(i), with T(i)=a +bi, and DL(i)=L(i+16)−2L(i) with L(i) being the DIL signal corresponding to the transmitted Ucode=i.

Abstract: A DSL modem with a receiver and a transmitter includes an LDPC encoder which utilizes a generation matrix G which is derived from a substantially deterministic H matrix in order to generate redundant parity bits for a block of bits. The H matrix is determined by assigning “ones” of a first column Nj randomly or deterministically. Then, beginning with the second column, assignment of “ones” is carried out deterministically with each “1” in a previous ancestor column generating a “1” in the next descendant column based on the rule that a descendant is placed one position below or above an ancestor. As a result, descending or ascending diagonals are generated. When distributing “ones” in any given column, care is taken to ensure that no rectangles are generated in conjunction with other “ones” in the current column and previous columns. By avoiding generation of rectangles, diagonals are interrupted.

Abstract: An interleaver for a digital modem is provided where consecutive codeword symbols are written in parallel into first cells of registers. Reading from registers for-interleaving purposes is dictated by a permutation table containing N−1 numbers which represent registers from which the current symbol should be read. Prior to data transmission, a calculation is made of lengths of the registers and a permutation table is determined. During data transmission, the first symbol in each codeword is sent directly to the output, the other symbols are sequentially written into the first cells of the corresponding registers, and the last cells of the registers are sequentially read in the order determined by the permutation table. After writing the incoming codeword into memory and reading the outgoing codeword, the contents of all memory registers are synchronously shifted by one cell in the output direction. A corresponding deinterleaver is also provided.

Abstract: A method for determining the encoding law of an incoming signal in a network which possibly contains an A-&mgr; or &mgr;-A conversion includes obtaining digital impairment learning (DIL) probing data, generating an ordered table of levels therefrom, using the table to find two functions, and using a logical analysis of the functions to determine the encoding law of the signal. A first function is a maximum from the values DL(i) and the threshold Th1 which are less than T(i), with T(i)=a+bi, and DL(i)=L(i+16)−2L(i) with L(i) being the DIL signal corresponding to the transmitted Ucode=i.

Abstract: The receiver of a PCM modem utilizes the V.90 TRN1d training signal for detecting whether any of the six slots of the received signal may be subject to alternating robbed bit signaling (ARBS), and what the alternating robbed bit signaling pattern may be. This is accomplished by accumulating the received level over a plurality of frames for each slot and by comparing the received levels for each slot to an average level for that slot. If the difference between the received levels and the average levels exceeds a threshold, the slot is determined to be subject to ARBS. Where a slot is subject to ARBS, DIL sequence signals for frames of the alternating robbed bit signaling slot having LSB=0 and LSB=1 are accumulated separately (if available) in order to generate two translation tables (TRT0, TRT1) for that slot. Where the DIL sequence is found only in the frames having the alternating robbed bit signaling slot having LSB=0 or having LSB=1, only one translation table can be generated.