3com Corporation

Other

Vlad Mitlin

Richard G C Williams

A Joseph Mueller

Tim Murphy

Timothy F Murphy

A method and apparatus implementing the method, of selecting a bit load b for a channel in a carrier system. The carrier system encodes data based on a constellation of points. Each point represents a tuple of data. The constellation has a self-similarity property. The bit load for the channel is selected based on the self-similarity property of the constellation. In an alternate embodiment, the method and apparatus are used to determine the bit load of the sub-channels in a multi-carrier system.

Method and apparatus for evaluating error control parameters of self-similar constellations

The present invention includes a method for selecting appropriate forward error correction and automatic repeat request parameters for protection of a multicarrier communication channel. The multicarrier communication channel may be wired or wireless. Particular aspects of the present invention are described in the claims, specification and drawings.

Method and apparatus for selection of ARQ parameters and estimation of improved communications

A method, and apparatus implementing the method, encodes bits to be transmitted over a channel. The channel may be a single carrier or a multi-carrier channel. Bits are encoded based on a constellation that has a self-similarity property and also has an improved bit error rate. The constellation was iteratively generated using a mirroring technique. In addition, a method, and apparatus, implementing the method, decodes bits that were received from a channel. The bits are decoded for a constellation that has a self-similarity property and that was generated using the mirroring technique.

Method and apparatus for improving error control properties for encoding and decoding data

A method and apparatus determines an uncoded bit error rate pbased on a target symbol error rate &#x3b5;. The uncoded bit error rate pis determined based on a weighted series expansion of the target symbol error rate &#x3b5;, comprising weights W that are a function of a maximum number of symbol errors that can be corrected t and a number of symbols in an information field K. The maximum number of symbol errors t and the number of symbols in the information field K is selected such that the uncoded bit error rate pthat produces a symbol error rate that is less than or equal to the target symbol error rate &#x3b5;is largest.

Performance evaluation of multicarrier channels

In accordance with the present invention, there are provided methods for estimating the level of interferers and the level of a useful signal in a spectral window of a given bandwidth in a communications channel in a complex multipath propagation environment. The first method of estimating the level of interferers comprises generating and transmitting several sets of sine waves on the Nyquist frequency. Each set is characterized by a certain phase so that the sequence of phase values evenly spans the interval (0, 2&#x3c0;) radians. The second method comprises generating and transmitting several sets of sine waves of the same phase, with frequencies evenly spanning a vicinity of the Nyquist frequency. The method of estimating the level of a useful signal comprises transmitting several repetitions of the signal used for actual data transmission and processing it by the receiving station.

Method for determining the quality of a communication channel

A method and apparatus selects forward error correction parameters in a channel having a plurality of subchannels in a multicarrier communications system. A signal-to-noise ratio representing a subset of the subchannels is determined. A number (s) of discrete multi-tone symbols in a forward-error-correction frame, a number (z) of forward-error-correction control symbols in the discrete multitone symbol associated with the signal-to-noise ratio, a number of subchannels associated with the signal-to-noise ratio, and a net coding gain for different values of s, z, signal-to-noise ratios and numbers of subchannels is stored in a table. Forward error correction parameters of the channel are selected based on the net coding gain by applying an approximation to a subset of values in the table.

Performance evaluation of a G.dmt-compliant digital subscriber line system

In one embodiment, a method and apparatus increases a bit load of a multicarrier system comprising a channel having a plurality of subchannels. A bit load is determined for at least one subchannel based on a target symbol error rate &#x3b5;a maximum number of symbol errors that can be corrected t, a number of symbols in an information field K, and a maximum number of transmissions k, and a number of bits per subchannel. The maximum number of symbol errors t, the number of symbols in the information field K and the maximum number of transmissions k, is selected such that a net coding gain is increased. In another embodiment, a method determines data flow for a channel having a plurality of subchannels in a multi-carrier system.

Performance evaluation of multicarrier channels with forward error correction and automatic retransmission request

In accordance with the present invention, there are provided peak-to-average power ratio optimal phase shifters for multi-carrier communications. An optimal shifter is shown to be a complex, constant envelope sequence mapped by a multi-tone transformation used to another complex, constant envelope sequence. In the case of the inverse discrete Fourier transform being the multi-tone transformation, a family of principal shifters of the form z(r)=exp(&#xb1;j*&#x3c0;*p*r/q), where j=&#x2212;1, 0&#x2266;r&#x3c;q, q is a number of subcarriers, and p and q are mutually prime integers of different parity, has been analytically constructed. These phase shifters outperform the best existing phase shifter by as much as 2.6 dB.

Phase shifters for peak-to-average power ratio reduction in multi-carrier communication systems

The present invention includes alternative methods for selecting forward error correction parameters to be used in multi channel communications. Method embodying aspects of the present invention may include acquiring signal to noise ratio data for a set of communications channels, counting, estimating or identifying channels to carry data, computing an average signal to noise ratio for channels used and selecting set(s) of FEC parameters. It may predicting net SNR gains and storing these predictions as splines or in interpolation tables. This invention is specifically applicable to Reed-Solomon encoding for FEC and selecting the Reed-Solomon parameters S and R/S. Symbol sets, represented by S may consist of dmt symbols or of data carried by multiple channels in one transmission interval. The computations for selecting parameters may include adjusting the average signal to noise ratio by a safety margin. The selected sets of parameters may be chosen from sets identified by a sending terminal and may be forwarded from a receiving terminal to a sending terminal.

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San Diego, CA, United States of America

Vlad Mitlin