Variable spacing pulse position modulation for ultra-wideband communication links
First Claim
1. A method for modulating a communications signal across a communications channel, comprising:
- receiving the communications signal including a plurality of input data bits, each input data bit having a first value or a second value;
receiving at least one time hopping code sequence comprising Nc elements, each element having a code value;
encoding each set of M input data bits into a symbol having a symbol value in the range of 0 to (2M−
1), the symbol comprising Nc chips, each chip consisting of 2M sub-chips, wherein each of the 2M sub-chips comprises Np time slots;
generating a pulse in one of the 2M sub-chips that corresponds to the symbol value;
associating the at least one time hopping code sequence with each symbol value;
associating each code value in the at least one time hopping code sequence with at least one chip in the symbol; and
shifting the position of the pulse within the sub-chip in each chip to at least one of the Np time slots, wherein the time slot corresponds to the code value associated with that chip.
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Abstract
Methods and systems for generating a variable spacing pulse position modulated (VSPPM) signal for transmission across an ultra-wideband communications channel. The variable pulse position modulated spread spectrum signal is created by encoding every M input data bits from an input data stream into a symbol consisting of Nc chips. Each chip is divided into 2M sub-chips and each sub-chip is further divided into Np time slots. A pulse is transmitted for each chip in the symbol. During each chip period, the pulse is placed in the sub-chip corresponding to the binary M-tuple (or symbol) value. A time hopping code sequence consisting of Nc elements with a one-to-one chip association is then applied to each symbol so that the position of each pulse is shifted to the appropriate time slot that corresponds to the time hopping code value.
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Citations
14 Claims
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1. A method for modulating a communications signal across a communications channel, comprising:
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receiving the communications signal including a plurality of input data bits, each input data bit having a first value or a second value; receiving at least one time hopping code sequence comprising Nc elements, each element having a code value; encoding each set of M input data bits into a symbol having a symbol value in the range of 0 to (2M−
1), the symbol comprising Nc chips, each chip consisting of 2M sub-chips, wherein each of the 2M sub-chips comprises Np time slots;
generating a pulse in one of the 2M sub-chips that corresponds to the symbol value;associating the at least one time hopping code sequence with each symbol value; associating each code value in the at least one time hopping code sequence with at least one chip in the symbol; and shifting the position of the pulse within the sub-chip in each chip to at least one of the Np time slots, wherein the time slot corresponds to the code value associated with that chip. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An ultra-wideband (UWB) transmitter operable for transmitting a pulse position spread spectrum signal over a communications channel, comprising:
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a spread spectrum encoder operable for; receiving at least one time hopping code sequence comprising Nc elements, each element consisting of a code value; receiving a signal including a plurality of input data bits comprising a plurality of binary bits; applying the at least one time hopping code sequence to encode M binary bits into symbols with values in the range of 0 to (2M−
1), each symbol consisting of a number of predefined chips, Nc, each chip consisting of 2M sub-chips, and each sub-chip consisting of Np time slots;associating the at least one time hopping code sequence with each symbol value; and associating at least one code value with each sub-chip in each chip in the symbol; a time-hopping code generator connected to the spread spectrum encoder for generating the least one time hopping code sequence; a pulse generator for generating a plurality of pulses; and a pulse position modulator for modulating the encoded symbols with the plurality of pulses generated by the pulse generator; and a transmission unit for transmitting the symbols from the spread spectrum encoder as the pulse position spread spectrum signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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Specification