Packet Format Detection via Repeated Legacy Signal Field
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently detecting and decoding packets in different formats, particularly in high-density scenarios where 802.11ax packets coexist with legacy 802.11a/g/n/ac packets, leading to issues with AGC resetting and packet format differentiation.
Innovation Solution
A transmission method and apparatus that generate and transmit packets with a repeated legacy signal field (RL-SIG) configured based on the presence of a second non-legacy signal field, allowing for efficient detection and decoding by using BPSK mapping rules, pilot patterns, or modified L_Rate fields to indicate the presence of additional signal fields and differentiate packet formats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 802.11ax packets use repeated legacy signal field (RL-SIG) with optional second non-legacy signal field, then packet format detection accuracy is improved, but packet structure complexity increases
Solution Approach 1:
The packet preamble is segmented into distinct fields including legacy signal field (L-SIG), repeated legacy signal field (RL-SIG), first non-legacy signal field (HE-SIG-A), and optional second non-legacy signal field (HE-SIG-B). Each field serves specific detection functions, allowing receivers to identify packet formats through systematic field analysis.
Solution Approach 2:
The RL-SIG field is transmitted immediately after L-SIG to provide preliminary format indication before the receiver needs to process the full packet. This preliminary signal field enables early packet format detection and AGC resetting preparation, improving detection accuracy without requiring complex analysis of subsequent fields.
2Adaptability or versatility
If receiver supports multiple packet formats for coexistence, then network compatibility is improved, but AGC resetting timing becomes more difficult to manage
Solution Approach 1:
The RL-SIG field provides preliminary information about packet format and duration before the actual data transmission begins. This allows the receiver to pre-configure AGC resetting timing and other reception parameters in advance, ensuring proper AGC adjustment is completed before the data field starts, thereby managing multi-format compatibility without timing conflicts.
Solution Approach 2:
The repeated legacy signal field structure provides feedback mechanisms that allow receivers to verify packet format assumptions and adjust AGC resetting accordingly. The consistent repetition pattern in RL-SIG gives reliable timing information that feedback loops can use to synchronize AGC adjustments with packet boundaries.
3Measurement precision
If legacy signal field is repeated to enable format detection, then packet differentiation capability is improved, but transmission time increases
Solution Approach 1:
The RL-SIG field uses parameter variations (such as modulation scheme, coding rate, or field content) to encode packet format information efficiently. By changing these parameters rather than simply repeating the entire L-SIG field, the system achieves improved packet differentiation with minimal additional transmission time overhead.
Data Source
AI summary
A transmission apparatus comprises circuitry that generates a physical protocol data unit (PPDU) that contains a legacy signal field and a first signal field wherein both of the legacy signal field and the first signal field comprise an Orthogonal Frequency Division Multiplexing (OFDM) symbol, and the first signal field is derived from the legacy signal field, and a transmitter, which, in operation, transmits the PPDU. A format of the PPDU is indicated based on whether a part of bits of the first signal field is inverted or not. The format of the PPDU is a first format or a second format, and data subcarriers of the first signal field in the second format have inverted values of corresponding values in the legacy signal field, and pilots of the first signal field in the second format are not inverted and have same values of corresponding values in the legacy signal field.