Wi-Fi Preamble Detection Using Barker Code Spreading
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Solution Overview
Problem
Traditional 802.11 Wi-Fi technologies face challenges in providing reliable low-power and long-distance wireless communication for IoT devices due to low detection performance of preamble and header fields under weak-signal conditions, limiting their ability to meet market requirements for IoT devices with large coverage areas and low power consumption.
Innovation Solution
The proposed solution involves replacing scrambled pseudo-random bit sequences in the SYNC field with fixed patterns and extending the spreading codes for the SYNC, SFD, and header fields using Barker codes, which increases the length of the spreading codes to improve detection and reception rates without altering chip rates or signal bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If channel encoding and decoding of MPDU data portion is added to normal 802.11b mode, then data receiving reliability is improved, but detection performance of SYNC field, SFD field, and PLCP header field remains insufficient under weak-signal conditions
Solution Approach 1:
The patent applies parameter changes by replacing the scrambled pseudo-random bit sequence in the SYNC field with a fixed pattern and by extending the spreading code length for SFD and PLCP header fields. These parameter modifications enhance the detection performance of these fields under weak-signal conditions without compromising the channel encoding/decoding improvements for MPDU data portion.
2Measurement precision
If detection performance of SYNC field, SFD field, and PLCP header field is improved, then packet detection bottleneck is removed, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent uses a fixed pattern instead of a scrambled pseudo-random sequence in the SYNC field, which simplifies the detection process by providing a known, predictable pattern that can be easily correlated with received signals. This inversion of the approach (from random to fixed) improves detection performance while actually reducing processing complexity.
Solution Approach 2:
The patent extends the spreading code length for SFD and PLCP header fields in advance, creating a more robust signal structure before transmission. This preliminary enhancement of the signal structure allows for better detection performance without requiring complex real-time processing during reception.
3Measurement precision
If spreading code length is extended for SFD field and header field, then reception sensitivity is improved, but signal bandwidth remains unchanged requiring higher processing rates
Solution Approach 1:
The patent extends the spreading code length by using periodic repetitions of the Barker code sequence. This periodic structure allows the extended spreading code to be processed in a systematic manner, improving reception sensitivity while maintaining a regular processing rhythm that can be efficiently implemented in hardware.
Data Source
AI summary
The present invention discloses a method for processing a preamble sequence and header for a data packet, comprising the following steps of: using a bit sequence of a fixed pattern to replace a scrambled pseudo-random bit sequence in a SYNC field in the preamble sequence, and spreading the SYNC field by a Barker code; extending a length of a spreading code and spreading an SFD field in the preamble sequence by the extended spreading code; and extending a length of a spreading code and spreading a header field by the extended spreading code. The present invention may significantly improve the performance of reception and detection for the preamble sequence (the SYNC field and the SFD field) and the PLCP header field, better overcome long-distance channel conditions, enhance the signal stability of transmission; and meanwhile the present invention is easy to implement and only requires little modifications to the circuit of a conventional Wi-Fi device.