Interference-Cancellation-Based CCA Adjustment in Distributed WLAN
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Solution Overview
Problem
Existing wireless local area network (WLAN) systems face challenges in efficiently managing interference between multiple radio heads, leading to suboptimal channel utilization and reduced data transmission capabilities due to the inability to accurately assess clear channel availability amidst interference from other radio heads and client devices.
Innovation Solution
A distributed system comprising a central controller and multiple radio heads, where the central controller performs Clear Channel Assessment (CCA) and mitigates interference by canceling out interfering signals, allowing simultaneous data transmission and reception while ensuring energy received at each radio head meets the CCA threshold, thereby enabling parallel communication with multiple client devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple radio heads transmit simultaneously in parallel, then data transmission efficiency and channel utilization are improved, but interference between radio heads increases causing CCA threshold violations
Solution Approach 1:
The system converts the harmful interference between radio heads into a beneficial signal by having the central controller calculate and cancel the interfering signal from the transmitting radio head at the receiving radio head, allowing simultaneous parallel transmissions while maintaining CCA threshold compliance
Solution Approach 2:
The central controller acts as an intermediary that coordinates between multiple radio heads, managing their transmissions and receiving operations to enable parallel communication while mitigating interference through signal cancellation calculations
2Productivity
If CCA threshold is lowered to allow more simultaneous transmissions, then channel utilization improves, but reliability of signal detection deteriorates
Solution Approach 1:
The system dynamically adjusts the CCA threshold parameter based on the calculated interference from simultaneous transmissions, allowing the threshold to be lowered when interference cancellation is available while maintaining reliable signal detection through adaptive parameter modification
3Measurement precision
If a radio head performs CCA to detect clear channel, then channel availability is determined, but interfering signals from other radio heads cause false busy detection
Solution Approach 1:
The system converts the harmful interfering signals that cause false busy detection into a calculable and cancellable component, allowing the receiving radio head to accurately detect clear channels even when other radio heads are transmitting by subtracting the known interference signal
Data Source
AI summary
Embodiments herein describe a distributed system that includes a central controller coupled to a plurality of separate radio heads. Each of the radio heads is coupled to the central controller via respective wired backends (e.g., cables). The radio heads includes one or more transceivers (e.g., radios) and antennas for wireless communicating with client devices. In the embodiments herein, the central controller can perform a variant of CCA to determine if a first one of the radio head can transmit wireless signals to, or receive wireless signals from, a first client device while a second radio head is communicating with a second client device using a combination of RTS/CTS, channel sensing, and interference cancellation techniques.