Full-Duplex WLAN Access Point Scheduling and Self-Interference Cancellation
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Solution Overview
Problem
Conventional WLAN systems are half-duplex, preventing simultaneous uplink and downlink data transmission, which limits spectral efficiency and requires effective self-interference cancellation, currently lacking an effective full-duplex communication solution.
Innovation Solution
A full-duplex communication method and apparatus for WLAN systems, involving a channel contention unit, scheduling information determination, and transmission units to manage simultaneous uplink and downlink transmissions, including interrupt mechanisms and channel self-interference measurement, enabling centralized scheduling and control by the access point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full-duplex transmission is implemented in WLAN system, then spectral efficiency is improved, but self-interference cancellation complexity increases
Solution Approach 1:
The patent segments the self-interference cancellation process into three distinct stages: antenna-level cancellation (physically separating transmit and receive paths), RF-level cancellation (using analog circuits to cancel interference before digital processing), and baseband-level cancellation (using digital signal processing to remove residual interference). This segmentation allows each stage to handle a portion of the cancellation task, reducing the overall complexity at any single point while achieving the goal of enabling full-duplex transmission to improve spectral efficiency
Solution Approach 2:
The patent performs preliminary self-interference channel estimation and cancellation setup before actual full-duplex data transmission begins. The access point first establishes the self-interference channels during calibration phases, pre-computes cancellation coefficients, and configures the cancellation circuits in advance. This preliminary action reduces the real-time processing complexity during actual transmission, allowing the system to achieve high spectral efficiency without being overwhelmed by complex real-time cancellation computations
2Productivity
If simultaneous uplink and downlink transmission is enabled, then resource utilization is improved, but channel contention complexity increases
Solution Approach 1:
The patent inverts the traditional WLAN channel access model by having the access point centrally schedule full-duplex transmissions instead of allowing distributed contention among stations. The access point determines which stations will transmit uplink and which will receive downlink simultaneously, allocating resources in advance through scheduling decisions. This inversion from distributed contention to centralized scheduling reduces the complexity of coordinating simultaneous transmissions while improving resource utilization by eliminating idle time and conflicts
3Reliability
If self-interference cancellation is performed at multiple levels, then transmission reliability is improved, but system complexity increases
Solution Approach 1:
The patent divides the self-interference cancellation system into three hierarchical levels: antenna-level (physical separation and isolation), RF-level (analog cancellation circuits operating at radio frequency), and baseband-level (digital signal processing). Each level handles a specific portion of the interference cancellation task, with the antenna level providing gross isolation, the RF level providing analog cancellation of strong interference components, and the baseband level providing digital refinement. This segmentation improves transmission reliability through multi-layer protection while managing system complexity by distributing functions across different domains and layers, avoiding the need for any single component to be overly complex
Data Source
AI summary
A method includes: obtaining, by an access point AP, use permission of a channel; determining, by the AP after obtaining the use permission of the channel, scheduling information for a station STA participating in full-duplex transmission, where the scheduling information includes information about a first station that performs uplink transmission on the channel and information about a second station that performs downlink transmission on the channel at the same time, or the scheduling information includes information about a third station that simultaneously performs uplink and downlink transmission on the channel; and sending, by the AP, a trigger frame, where the trigger frame includes the scheduling information.