LDPC Parameter Derivation for IEEE 802.11ac Wireless Transmitters
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Solution Overview
Problem
The proposed IEEE 802.11ac standard introduces changes to the conventional LDPC encoding process, leading to issues with LDPC decoding on the receiving side, where the device may not recognize new signaling components or experience mapping issues between LDPC components, affecting error correction in wireless communication systems.
Innovation Solution
A method and system for LDPC encoding that determines initial and extra OFDM symbols to generate LDPC parameters, including an Nldpc_ext value based on STBC and extra symbols, ensuring correct LDPC parameter derivation at both transmitting and receiving devices, without requiring changes to the IEEE 802.11n encoding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the conventional LDPC encoding process is changed to comply with IEEE 802.11ac standard, then data throughput and channel efficiency are improved, but the receiving device may not recognize new signaling components or experience mapping issues between LDPC components
Solution Approach 1:
The transmitting device determines and signals the number of extra OFDM symbols (Nsym_ext) and LDPC extra symbols (Nldpc_ext) in advance within the packet header, allowing the receiving device to pre-calculate all necessary LDPC parameters before decoding begins. This preliminary action ensures that the receiver is properly prepared to recognize and correctly decode the LDPC signal according to the new 802.11ac standard.
2Measurement precision
If more bits are used for LDPC parameter determination, then decoding accuracy is improved, but the number of bits available for actual data transmission is reduced
Solution Approach 1:
The patent extracts the LDPC parameter information (Nsym_ext and Nldpc_ext) from the data payload and places it in the packet header as signaling information. This separation allows the parameters to be communicated efficiently without consuming data transmission bits, as they are transmitted as control information rather than payload data.
3Reliability
If puncturing is reduced to improve error correction, then reliability is improved, but data throughput decreases
Solution Approach 1:
The patent changes the LDPC code rate parameter by controlling the number of extra symbols (Nldpc_ext) added to the encoded signal. By adjusting this parameter, the system can achieve higher code rates with less puncturing, thereby improving error correction capability while maintaining higher data throughput compared to traditional approaches that rely on more aggressive puncturing.
Data Source
AI summary
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.