Multiple-access code generation
First Claim
1. A method for generating at least one multiple-access code wherein a transmitter is configured for performing the steps of;
- constructing a trellis having;
a plurality K×
N of state transition points,each of the K×
N state transition points including L nodes, whereinK is a number of multiple-access codes,N is a code length, andL is a number of a plurality of code-chip parameters;
constructing a fitness function that is computable for each of the plurality of state transition points;
appending at least one of the plurality of code-chip parameters to each multiple-access code corresponding to a winning path terminating at each of a plurality of nodes of a previous state transition point;
computing the fitness function for each multiple-access code; and
determining a winning path terminating at each node of a current state transition point.
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Accused Products
Abstract
Multiple-access codes are generated using an asymptotically optimal decoding algorithm, such as the Viterbi algorithm. A trellis may be constructed using a number of desired users, at least one code length, and a number of code-chip parameters. A fitness function is derived from a mathematical relationship between the multiple-access codes, and may include some measure of correlation of the codes. The multiple-access codes correspond to paths having optimal path metrics derived from the fitness function. Multiple iterations through the trellis may be performed to refine a selection of multiple-access codes.
39 Citations
14 Claims
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1. A method for generating at least one multiple-access code wherein a transmitter is configured for performing the steps of;
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constructing a trellis having; a plurality K×
N of state transition points,each of the K×
N state transition points including L nodes, whereinK is a number of multiple-access codes, N is a code length, and L is a number of a plurality of code-chip parameters; constructing a fitness function that is computable for each of the plurality of state transition points; appending at least one of the plurality of code-chip parameters to each multiple-access code corresponding to a winning path terminating at each of a plurality of nodes of a previous state transition point; computing the fitness function for each multiple-access code; and determining a winning path terminating at each node of a current state transition point. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A multiple-access coder, comprising:
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a first module configured for calculating branch metrics based on at least one fitness function for possible state transitions between two successive states; and a second module configured for calculating, as a function of said branch metrics, path metrics for possible paths constituted by successive state transitions and ending in each of said states, wherein the second module is further configured for appending at least one of a plurality of code-chip parameters to each multiple-access code corresponding to a winning path terminating at each of a plurality of nodes of a previous state transition point, computing the fitness function for each multiple-access code, and determining a winning path terminating at each node of a current state transition point.
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Specification