WLAN HARQ Soft Combining Through Early Descrambling
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Solution Overview
Problem
Wireless local area networks (WLANs) face limitations in range and signal quality due to low Modulation and Coding Scheme (MCS) indices and the inability to perform soft combining of multiple transmissions due to scrambling, which restricts the use of hybrid automatic repeat request (HARQ) and affects packet error rate (PER) and signal-to-noise ratio (SNR).
Innovation Solution
Implementing HARQ and soft combining of multiple transmissions by descrambling received frames before decoding, allowing for the combination of payloads and improving SNR, PER, and channel capacity, and extending communication range by using a processor to generate and combine descrambled bit estimate sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scrambling processing is applied at the transmitter, then security and signal randomization are improved, but the receiver cannot use soft combining of multiple transmissions
Solution Approach 1:
The patent inverts the conventional processing order by performing descrambling before decoding instead of after. This allows the receiver to apply soft combining to the descrambled payloads from multiple transmissions, improving reliability while managing complexity through the linear property of the encoding operation.
2Reliability
If HARQ is implemented without soft combining, then retransmission capability is provided, but packet error rate and signal-to-noise ratio performance are degraded
Solution Approach 1:
The patent performs descrambling as a preliminary action before decoding and soft combining. By preparing the payloads in advance through descrambling, the system enables effective soft combining of multiple transmissions, which improves both packet error rate and throughput efficiency by maximizing the benefit of retransmissions.
3Adaptability or versatility
If maximum range is limited by lowest MCS index, then compatibility is maintained, but communication range and signal quality are constrained
Solution Approach 1:
The patent changes the processing parameters by reversing the descrambling and decoding order. This parameter change enables soft combining of multiple transmissions at the lowest MCS indices, effectively extending communication range and improving signal quality while maintaining compatibility with existing MCS schemes.
Data Source
AI summary
Some embodiments enable improved packet error rate (PER), signal to noise ratio (SNR), channel capacity, aggregated throughput, and communication range in wireless communication systems. For example, an electronic device includes a buffer that stores a first descrambled bit estimate sequence. The electronic device further includes an encoder that receives a descrambling sequence and generates an encoded descrambling sequence and a multiplier circuit that receives a bit estimate sequence and the encoded descrambling sequence and generates a second descrambled bit estimate sequence. The electronic device also includes an adder circuit that combines the first descrambled bit estimate sequence and the second descrambled bit estimate sequence and a decoder that decodes the combined descrambled bit estimate sequence.