Full Duplex Wireless Medium Utilization via CEDA and Self-Interference Cancellation
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in medium utilization and increased latency due to half-duplex transmission methods, which lead to reduced throughput and poor user experience, especially in environments with many active stations.
Innovation Solution
The integration of Collision Early Detection and Avoidance (CEDA) mechanism with full-duplex transmission, utilizing dual-layer antenna arrays for self-interference cancellation and radio parameter calibration, allows for simultaneous downlink and uplink transmissions over a single frequency channel, enhancing medium usage efficiency and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If half-duplex transmission methods are used, then device complexity is reduced, but medium utilization efficiency deteriorates and transmission latency increases
Solution Approach 1:
The patent segments the transmission medium access into distinct phases: contention phase where stations compete for medium access, and transmission phase where full-duplex communication occurs. This segmentation allows the system to maintain simple CSMA/CA for medium access control while enabling complex full-duplex operations only when needed, thus improving medium utilization without proportionally increasing overall system complexity.
Solution Approach 2:
The patent transitions from traditional half-duplex time-division or frequency-division approaches to spatial dimension by using multiple antennas for simultaneous transmission and reception. This dimensional change enables full-duplex communication where downlink and uplink transmissions occur simultaneously in the same frequency channel, dramatically improving medium utilization efficiency.
2Productivity
If full-duplex transmission is implemented, then medium utilization efficiency is improved, but self-interference cancellation complexity increases
Solution Approach 1:
The patent performs preliminary calibration of radio parameters for RF and digital cancellation algorithms using the preamble as training sequence during the station's contending the medium. This preliminary action prepares the self-interference cancellation system in advance, reducing the complexity of real-time cancellation operations during actual full-duplex transmission.
Solution Approach 2:
The patent introduces dual-layer antenna arrays as an intermediary structure to facilitate self-interference cancellation. The dual-layer configuration provides spatial separation between transmit and receive antennas, creating a physical basis for effective self-interference cancellation while managing the complexity of the cancellation process.
3Loss of time
If collision detection is performed in early stage, then transmission latency is reduced, but medium access control complexity increases
Solution Approach 1:
The patent implements feedback mechanism where transmitting stations monitor the medium during transmission and detect collisions in early stage. When collision is detected, the system provides feedback to fast release the medium for new contention. This feedback approach reduces transmission latency by quickly identifying and aborting collided transmissions, while maintaining relatively simple medium access control through the familiar CSMA/CA framework.
4Productivity
If multiple pairs of DL and UL simultaneous transmissions are scheduled, then throughput is improved, but scheduling complexity increases
Solution Approach 1:
The patent makes the access point capable of simultaneously performing multiple functions: scheduling multiple pairs of downlink and uplink transmissions, calibrating radio parameters, performing self-interference cancellation, and managing medium access. This multi-functionality allows the system to achieve high throughput through coordinated full-duplex communications while centralizing the scheduling complexity in the access point rather than distributing it across all stations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves medium utilization efficiency, reduces transmission latency, and enhances user experience by enabling reliable simultaneous transmissions and mitigating hidden node issues in wireless local area networks.
Implementation Method 1
a full-duplexer to cancel self-interference using dual-layer antenna arrays for better cancellation performance
Implementation Method 2
a full-duplexer to calibrate radio parameters for RF and digital cancellation algorithms using the preamble as training sequence during the station's contending the medium
Data Source
AI summary
Multiple wireless devices in a network perform full duplex communication in which the transmission path and receiving path are spatially separated to allow simultaneous transmission and receiving. The wireless devices can either be controlled using a centralized, or point, coordination function or a distributed coordination function. A full-duplex wireless device senses the medium during transmission by itself and selectively continues the transmission when a signal is sensed on the medium. A full-duplex wireless device measures signal being transmitted by its transmitter and estimates parameters that can be used to cancel the contribution of the locally transmitted signal to the locally received signal concurrently being received during the transmission. The transmit antenna and the receive antenna of a full-duplex wireless device can be configured to be spatially isolated from each other to minimize interference between the antenna functions.