WLAN Receiver Early Decision on Single or Dual Channel Transmission
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Solution Overview
Problem
In Wireless Local Area Networks (WLANs), the latency in decoding bandwidth mode bits is long, causing receivers to fail in tuning secondary TX/RX chains in time to prepare for receiving the second part of a frame preamble, especially when operating in dual-channel modes like 160/(80+80)MHz, leading to potential data loss and inefficiency.
Innovation Solution
Implementing a method where the control circuitry decodes the first part of the frame preamble to determine whether the second part is transmitted over a single channel or both channels, allowing early tuning of secondary TX/RX chains to the appropriate channel, using techniques such as Viterbi decoding, matched filters, or correlating signals across sub-bands, and utilizing a Local Oscillator (LO) multiplexer to dynamically switch between channel modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the receiver decodes the entire first part of the frame preamble before making a decision on transmission mode, then the decision accuracy is improved, but the latency increases causing the receiver to fail in tuning secondary TX/RX chains in time
Solution Approach 1:
The receiver performs preliminary decoding of the first part of the frame preamble to detect transmission mode indicators before the entire preamble is received. This allows the receiver to proactively tune secondary TX/RX chains to the appropriate channel (first or second channel) in advance, resolving the contradiction by making an early informed decision rather than waiting for complete preamble reception.
Solution Approach 2:
The frame preamble is segmented into a first part containing transmission mode indicators and a second part containing data. The receiver processes the first part separately and makes tuning decisions based on decoded indicators from this segment, allowing parallel processing and reducing overall latency while maintaining decision accuracy.
2Measurement precision
If the receiver waits to receive the entire first part before decoding, then decoding accuracy is improved, but the receiver cannot prepare secondary TX/RX chains in time for dual-channel modes
Solution Approach 1:
The receiver performs preliminary decoding of the first part of the frame preamble as soon as it is received, extracting transmission mode indicators before the entire preamble arrives. This enables the receiver to proactively configure secondary TX/RX chains for the correct channel, ensuring reliable reception of subsequent dual-channel data without compromising decoding accuracy through premature processing.
3Device complexity
If the system uses fixed channel tuning for all frames, then device complexity is reduced, but the system cannot support dynamic bandwidth usage including 160/(80+80)MHz modes
Solution Approach 1:
The system dynamically tunes secondary TX/RX chains based on transmission mode indicators decoded from the frame preamble. The control circuitry adjusts channel configuration in real-time according to the detected mode (single-channel or dual-channel), enabling flexible support for various bandwidth modes including 160/(80+80)MHz while maintaining manageable device complexity through automated adaptation.
Solution Approach 2:
The secondary TX/RX chains are designed to be multi-functional, capable of operating on either the first channel or the second channel depending on the transmission mode. This universal design allows the same hardware resources to serve multiple bandwidth configurations without requiring dedicated chains for each mode, balancing adaptability with complexity.
Data Source
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AI summary
A Wireless Local Area Network (WLAN) device (20) includes multiple transmission/reception (TX/RX) chains (36), and control circuitry (124, 130). The TX/RX chains include first TX/RX chains (36A, 36B) tuned to a first channel, and second TX/RX chains (36C, 36D) that are selectively tuned to the first channel or to a different second channel. The control circuitry is configured to receive, via at least one of the TX/RX chains, a frame preamble signal including a first part and a second part, which are both transmitted over either the first channel alone or over both the first and second channels, and the first part is decoded from the first channel alone, to make a decision, before receiving the entire first part, whether the second part is transmitted over the first channel alone or over both the first and second channels, and to tune the second TX/RX chains to the first channel or to the second channel, based on the decision.