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US 9,432,234 B2Granted
Frequency interleaving and de-interleaving for OFDM modulation
AssigneeBroadcom Corporation
InventorRichard Stephen Prodan
Life of this patent
Estimating the term…
Abstract
A device implements orthogonal frequency division multiplexing (OFDM) techniques. In particular, the device includes a frequency interleaver and/or de-interleaver for OFDM modulation. The frequency interleaver provides random frequency interleaving for the symbols transmitted by OFDM modulation. The frequency de-interleaver provides random frequency de-interleaving for the symbols received by OFDM demodulation.
Claims20
A communication device comprising:
- a transceiver for data communication in a transmission spectrum over a channel;
- a memory;
- and
- system circuitry in data communication with the memory and the transceiver, the system circuitry configured to format data symbols for transmission by the transceiver over the channel, the system circuitry configured to:
- receive data for transmission over the channel;
- modulate respective subcarriers of a plurality of subcarriers with the data to define subcarrier data;
- store the subcarrier data in a subcarrier matrix in the memory in a pseudo-random order, including applying a row rotation of subcarriers in the subcarrier matrix and a column rotation of the subcarriers in the subcarrier matrix to substantially randomize location of the respective subcarriers across the transmission spectrum when the subcarrier data is read from the subcarrier matrix;
- and
- provide the subcarrier data from the subcarrier matrix to the transceiver for generation of the respective subcarriers and communication of the respective subcarriers on the channel.
6 more elements
A method comprising:
- at a data communication device,
- receiving data symbols to be transmitted over a channel;
- frequency interleaving the data symbols to be transmitted, including
- writing frequency subcarrier identifiers into a memory in a pseudo-random order as a two dimensional array having a plurality of rows and a plurality of columns, the subcarrier identifiers identifying respective subcarriers of a plurality of subcarriers to be modulated with data to be transmitted, including:
- rotating subcarrier identifiers of the two-dimensional array along one or more rows of the plurality rows, and
- rotating subcarrier identifiers of the two-dimensional array along one or more columns of the plurality of columns;
- and
- determining frequency subcarriers for transmitting the symbols by indexing into the memory.
5 more elements
A method comprising:
- at a data communication device,
- receiving data symbols to be transmitted over a channel;
- frequency interleaving the data symbols to be transmitted, including
- writing frequency subcarrier identifiers into a memory in a pseudo-random order as a two dimensional array, the subcarrier identifiers identifying respective subcarriers of a plurality of subcarriers to be modulated with data to be transmitted, the pseudo-random order being determined by:
- using a linear feedback shift register (LFSR);
- determining a cyclic redundancy check (CRC) value for a bit row address of the two-dimensional array;
- and
- wherein writing the frequency subcarrier identifiers into the two dimensional array comprises writing the frequency subcarrier identifiers into a row of the two dimensional array given using the CRC value;
- rotating the frequency subcarrier identifiers written into a respective row of the two dimensional array by the CRC value of the bit row address for the respective row modulo a number of columns in the respective row, using the CRC value of [K−1 minus a column address for the particular column], wherein K is a number of columns in the two dimensional array;
- wherein the pseudo-random order comprises an ordering of the frequency subcarrier identifiers written in the two dimensional array read column-wise from row 0, column 0 to row C−1, column K−1 of the two dimensional array, wherein C=NI2L(K−1) and wherein 2L is a number of rows in the two dimensional array and NI is the number of frequency subcarriers in the symbols to be transmitted, including data subcarriers and pilot placeholder subcarriers, and where C comprises a number of subcarriers and where the two dimensional array comprises 2L rows;
- and
- determining frequency subcarriers for transmitting the symbols by indexing into the memory.
9 more elements
A method comprising:
- at a data communication device,
- receiving input subcarrier numbers for data communication of an orthogonal frequency division multiplexed (OFDM) symbol over a channel;
- storing respective input subcarrier numbers in sequential order in a two-dimensional subcarrier matrix in a memory device;
- relocating each respective input subcarrier number in row r, column c of the subcarrier matrix into a permuted output subcarrier number in the subcarrier matrix at a position given by:
- sc
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- where K is the total number of columns of the subcarrier matrix, C is the number of rows in the last column of the subcarrier matrix, and where sc(r,c) ε [0, 1, . . . , NI−1] and sc0[n] is an array of 2L elements, where each element contains the cumulative number of input subcarriers previously written into the subcarrier matrix prior to writing input row n into the permuted output row;
- and
- reading the subcarrier numbers from the subcarrier matrix to transmit the OFDM symbol over the channel.
114 more elements
Dependencies are inferred from the claim text.