Bit interleaving for orthogonal frequency division multiplexing in the transmission of digital signals
AssigneeQUALCOMM Incorporated
InventorsRajiv Vijayan, Joseph P. Odenwalder, Jack K. Wolf, Chong U. Lee, Ephraim Zehavi
Life of this patent
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Abstract
In an orthogonal frequency division multiplexing (OFDM) system which uses an outer Reed-Solomon encoder and interleaver an inner convolutional encoder, after the inner convolutional encoding the data bits are interleaved, and then grouped into symbols, each symbol having “m” bits. After grouping, the symbols are mapped to a complex plane using quadrature amplitude modulation (QAM). Thus, bits, not symbols, are interleaved by the inner interleaver. A receiver performs a soft decision regarding the value of each bit in each complex QAM symbol received.
Claims32
For an orthogonal frequency division multiplex (OFDM) signal receiver for receiving complex symbols in the OFDM signal, each symbol representing “m” data bits, a computer logic device comprising:
- a computer logic storage device readable by a digital processing system;
- and
- instructions embodied in the logic storage device, the instructions being executable by the digital processing system for performing method steps for undertaking a soft decision regarding a value of each symbol, the method steps comprising:
- determining a first set of possible values for each symbol, each value in the first set having a binary value of “0” in a predetermined bit;
- determining, for each symbol, a magnitude difference between the symbol and each possible value in the first set of possible values;
- and
- determining the smallest magnitude difference and generating a first signal representative thereof;
- determining a second set of possible values for each symbol, each value in the second set having a binary value of “1” in a predetermined bit;
- determining, for each symbol, a magnitude difference between the symbol and each possible value in the second set of possible values;
- determining the smallest magnitude difference and generating a second signal representative thereof, wherein determining a first set of possible values for each symbol further comprises:
- determining a first set of estimated values of the symbol, and determining a second set of possible values for each symbol further comprises:
- determining a second set of estimated values for each symbol and wherein the first and second set of estimated values is based on a pilot signal.
For a receiver receiving “n” substreams of an orthogonal frequency division multiplexed (OFDM) signal containing complex phase-adjusted symbols, each symbol representing “m” data bits, a device, comprising:
- for each substream, a soft decision quantizer for determining a binary value of each bit represented by each symbol in the substream, the soft decision quantizer further comprising:
- means for determining a first set of possible values for each symbol, each value in the first set having a binary value of “0” in a predetermined bit;
- means for determining, for each symbol, a magnitude difference between the symbol and each possible value in the first set of possible values;
- and
- means for determining the smallest magnitude difference and generating a first signal representative thereof.
For an orthogonal frequency division multiplex (OFDM) signal receiver for receiving complex symbols in the OFDM signal, each symbol representing “in” data bits, a computer logic device comprising:
- a computer logic storage device readable by a digital processing system;
- and
- instructions embodied in the logic storage device, the instructions being executable by the digital processing system for performing method steps for undertaking a soft decision regarding a value of each symbol, the method steps comprising:
- determining a first set of possible values for each symbol, each value in the first set having a binary value of “0” in a predetermined bit;
- determining, for each symbol, a magnitude difference between the symbol and each possible value in the first set of possible values;
- and
- determining the smallest magnitude difference and generating a first signal representative thereof.
For a receiver receiving “n” substreams of an orthogonal frequency division multiplexed (OFDM) signal containing complex phase-adjusted symbols, each symbol representing “m” data bits, a method for determining a binary value of each bit represented by each symbol in the substeam, the method comprising:
- determining a first set of possible values for each symbol, each value in the first set having a binary value of “0” in a predetermined bit;
- determining, for each symbol, a magnitude difference between the symbol and each possible value in the first set of possible values;
- and
- determining the smallest magnitude difference and generating a first signal representative thereof.
A device for receiving “n” substreams of an orthogonal frequency division multiplexed (OFDM) signal including complex phase-adjusted symbols, each symbol representing “m” data bits, the device comprising:
- a plurality of soft decision quantizers corresponding to the “n” substreams, each soft decision quantizers configured to determine a value of each symbol in a corresponding substream;
- a parallel to serial converter to combine the data bits from the plurality of soft decision quantizers;
- a de-interleaver to reorder the data bits into an order that the data bits were in before being interleaved;
- and
- a decoder to decode the data bits.
A method for receiving “n” substreams of an orthogonal frequency division multiplexed (OFDM) signal including complex phase-adjusted symbols, each symbol representing “m” data bits, the method comprising:
- using a plurality of soft decision quantizers corresponding to the “n” substreams to determine a value of each symbol in a corresponding substream;
- combining the data bits generated by the plurality of soft decision quantizers;
- re-ordering the combined data bits into an order that the data bits were in before being interleaved;
- and
- decoding the re-ordered data bits.
For a receiver receiving “n” substreams of an orthogonal frequency division multiplexed (OFDM) signal containing complex phase-adjusted symbols, each symbol representing “m” data bits, a method for determining a binary value of each bit represented by each symbol in the substeam, the method comprising:
- determining a first set of possible values for each symbol, each value in the first set having a binary value of “0” in a predetermined bit;
- determining, for each symbol, a magnitude difference between the symbol and each possible value in the first set of possible values;
- and
- determining the smallest magnitude difference an generating a first signal representative thereof;
- determining a second set of possible values for each symbol, each value in the second set having a binary value of “1” in a predetermined bit;
- determining, for each symbol, a magnitude difference between the symbol and each possible value in the second set of possible values;
- and
- determining the smallest magnitude difference an generating a second signal representative thereof, wherein the means for determining a first set of possible values for each symbol further comprises:
- determining a first set of estimated values of the symbol, and determining a second set of possible values for each symbol further comprises:
- determining a second set of estimated values for each symbol and wherein the first and second set of estimated values is based on a pilot signal.
Computer logic storage device storing instructions for use in receiving complex symbols in the orthogonal frequency division multiplex (OFDM) signal for undertaking a soft decision regarding a value of each symbol, wherein each symbol represents “m” data bits, the computer logic device comprising:
- instructions for determining a first set of possible values for each symbol, each value in the first set having a binary value of “0” in a predetermined bit;
- instructions for determining, for each symbol, a magnitude difference between the symbol and each possible value in the first set of possible values;
- and
- instructions for determining the smallest magnitude difference and generating a first signal representative thereof;
- instructions for determining a second set of possible values for each symbol, each value in the second set having a binary value of “1” in a predetermined bit;
- instructions for determining, for each symbol, a magnitude difference between the symbol and each possible value in the second set of possible values;
- instructions for determining the smallest magnitude difference and generating a second signal representative thereof, wherein the instructions for determining a first set of possible values for each symbol further comprises:
- instructions for determining a first set of estimated values of the symbol, and the instructions for determining a second set of possible values for each symbol further comprises:
- instructions for determining a second set of estimated values for each symbol and wherein the first and second set of estimated values is based on a pilot signal.
Dependencies are inferred from the claim text.