System and method for transmitting a low density parity check signal

Patent metadata

Field	Value
Publication number	US-9749090-B2
Application number	US-201414156834-A
Country	US
Kind code	B2
Filing date	Jan 16, 2014
Priority date	Sep 16, 2010
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

A system and method for transmitting LDPC parameters is provided. In the method, an initial number of OFDM symbols (Nsym_init) is determined for a packet that is based on the number of information bits to be delivered in the packet. An STBC value is also determined. A number of extra symbols (Nsym_ext) value is generated based on the Nsym_init value, wherein a Nsym value is based on said Nsym_init value and said Nsym_ext value. An Nldpc_ext value is determined based on the STBC value and the Nsym_ext value for purposes of determining LDPC parameters associated with the packet.

First claim

We claim:

1. A method for implementing low density parity check (LDPC) error coding, comprising:
determining an initial number of orthogonal frequency division multiplexing (OFDM) symbols corresponding to a number of information bits to be delivered in a packet;
determining a space time block coding (STBC) value that reflects whether STBC is to be employed in transmitting the packet;
determining a number of extra OFDM symbols to be added to the initial number of OFDM symbols based at least in part on one or more LDPC parameters used to encode the information bits, wherein a final number of OFDM symbols is based on the initial number of OFDM symbols and the number of extra OFDM symbols;
generating an LDPC extension value based on the STBC value and the number of extra OFDM symbols that are added to the initial number of OFDM symbols; and
transmitting the packet to a receiving device, wherein the packet includes information indicating the LDPC extension value and the final number of OFDM symbols to enable the receiving device to determine a one-to-one mapping between the initial number of OFDM symbols and a number of bits in a data structure and service field of the packet.

2. The method of claim 1 , further comprising:
performing shortening and puncturing operations to determine the final number of OFDM symbols.

3. The method of claim 1 , wherein the packet is in compliance with an IEEE 802.11ac standard or its derivatives.

4. The method of claim 1 , wherein:
the final number of OFDM symbols is an integer value; and
a number of code words in the packet is an integer value.

5. The method of claim 1 , further comprising:
maximizing a media access control layer (MAC) padding to a maximum number of bytes to provide the one-to-one mapping between the initial number of OFDM symbols and the number of bits in the data structure and service field of the packet.

6. The method of claim 1 , wherein:
the LDPC extension value is 0 when the STBC value is 0 and the number of extra OFDM symbols is 0;
the LDPC extension value is 1 when the STBC value is 0 and the number of extra OFDM symbols is 1;
the LDPC extension value is 0 when the STBC value is 1 and the number of extra OFDM symbols is 0; and
the LDPC extension value is 1 when the STBC value is 1 and the number of extra OFDM symbols is 2.

7. A system for implementing low density parity check (LDPC) error coding comprising:
an LDPC encoder configured to:
determine an initial number of orthogonal frequency division multiplexing (OFDM) symbols corresponding to a number of information bits to be delivered in a packet; and
determine a number of extra OFDM symbols to be added to the initial number of OFDM symbols based at least in part on one or more LDPC parameters used to encode the information bits, wherein a final number of OFDM symbols is based on the initial number of OFDM symbols and the number of extra OFDM symbols

an extension calculator configured to:
determine a space time block coding (STBC) value that reflects whether STBC is to be employed in transmitting the packet; and
generate an LDPC extension (Nldpc_ext) value based on the STBC value and the number of extra OFDM symbols that are added to the initial number of OFDM symbols; and

a transmitter configured to transmit the packet to a receiving device, wherein the packet includes information indicating the LDPC extension value and the final number of OFDM symbols enable the receiving device to determine a one-to-one mapping between the initial number of OFDM symbols and a number of bits in a data structure and service field of the packet.

8. The system of claim 7 , wherein the LDPC encoder is to perform shortening and puncturing operations to determine the final number of OFDM symbols.

9. The system of claim 7 , further comprising:
a media access control layer (MAC) padder configured to maximize a MAC padding to a maximum number of bytes to provide the one-to-one mapping between the initial number of OFDM symbols and the number of bits in the data structure and service field of the packet.

10. The system of claim 7 , wherein when the Nldpc_ext value is 1, the number of extra OFDM symbols is 1 when said the STBC value is 0; and the number of extra OFDM symbols is 2 when the STBC value is 1.

11. The system of claim 7 , wherein:
the Nldpc_ext value is 0 when the STBC value is 0 and the number of extra OFDM symbols is 0;
the Nldpc_ext value is 1 when the STBC value is 0 and the number of extra OFDM symbols is 1;
the Nldpc_ext value is 0 when the STBC value is 1 and the number of extra OFDM symbols is 0; and
the Nldpc_ext value is 1 when the STBC value is 1 and the number of extra OFDM symbols is 2.

12. A method for a low density parity check (LDPC) decoding, comprising:
receiving a packet including information indicating an LDPC extension value and a final number of OFDM symbols associated with the packet;
determining a number of extra OFDM symbols based on the LDPC extension value and a space time block coding (STBC) value that reflects whether STBC is employed in transmitting the packet; and
determining an initial number of OFDM symbols based on the number of extra OFDM symbols and the final number of OFDM symbols, wherein the initial number of OFDM symbols corresponds to a number of information bits delivered in the packet;
determining a one-to-one mapping between the initial number of OFDM symbols and a number of bits in a data structure and service field of the received packet;
determining one or more LDPC parameters used to encode the information bits based at least in part on the number of bits in the data structure and service field of the received packet; and
decoding the received packet based on the one or more LDPC parameters.

13. The method of claim 12 , wherein:
the number of extra OFDM symbols is 1 when the STBC value is 0 and the LDPC extension value is 1; and
the number of extra OFDM symbols is 2 when the STBC value is 1 and the LDPC extension value is 1.

14. The method of claim 12 , wherein the number of extra OFDM symbols is 0 when the LDPC extension value is 0.

15. The method of claim 12 , wherein the final number of OFDM symbols is provided in a signal field of the received packet.

16. The method of claim 12 , wherein the packet is in compliance with an IEEE 802.11ac standard or its derivatives.

17. A system for implementing low density parity check (LDPC) error coding, comprising:
one or more receivers configured to receive a packet including information indicating an LDPC extension value and a final number of OFDM symbols associated with the packet; and
an LDPC decoder configured to:
determine a number of extra OFDM symbols based on the LDPC extension value and a space time block coding (STBC) value that reflects whether STBC is employed in transmitting the packet;
determine an initial number of OFDM symbols based on the number of extra OFDM symbols and the final number of OFDM symbols, wherein the initial number of OFDM symbols corresponds to a number of information bits delivered in the packet;
determine a one-to-one mapping between the initial number of OFDM symbols and a number of bits in a data structure and service field of the received packet;
determine one or more LDPC parameters used to encode the information bits based at least in part on the number of bits in the data structure and service field of the received packet; and
decode the received packet based on the one or more LDPC parameters.

Assignees

• Qualcomm Inc

Inventors

• Shi Kai
• Zhang Ning

Classifications

• H04L69/22

  Parsing or analysis of headers · CPC title

• H04L1/0618

  Space-time coding · CPC title

• H04L1/0065

  Serial concatenated codes · CPC title

• H04L27/2627

  Modulators · CPC title

• H04L1/0042

  Encoding specially adapted to other signal generation operation, e.g. in order to reduce transmit distortions, jitter, or to improve signal shape (H04L1/0067 takes precedence) · CPC title