Listen After Talk Wireless Interference Avoidance
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Solution Overview
Problem
Listen before talk (LBT) procedures are ineffective in millimeter wave (mmW) systems due to increased overhead from frequent acknowledgments and channel state information feedback, which can lead to collisions when switching beams.
Innovation Solution
Implement a 'listen after talk' (LAT) procedure where a wireless transmission includes an interference avoidance preamble that indicates resources for an interference avoidance request, allowing devices to enable mechanisms like LBT, FDM, TDM, or spatial multiplexing after detecting interference, thereby reducing overhead until necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT procedures are used to avoid interference, then collision avoidance is improved, but overhead increases due to frequent acknowledgments and channel state information feedback
Solution Approach 1:
The transmitter performs LBT procedure in advance before transmitting the signal to the receiver. This preliminary channel access check ensures the channel is clear before transmission, avoiding collisions and reducing the need for retransmissions and feedback, thereby reducing overall overhead while maintaining reliability
Solution Approach 2:
The system dynamically adjusts the LBT procedure based on channel conditions and transmission requirements. The transmitter can adaptively select between different LBT modes (Type 1, Type 2a, Type 2b) and adjust parameters like contention window size and backoff counters, optimizing the balance between collision avoidance and overhead reduction
2Reliability
If LBT procedures are performed frequently to ensure reliable communication, then interference avoidance is improved, but communication efficiency decreases due to increased overhead
Solution Approach 1:
The LBT procedure is performed once in advance before the transmission begins, establishing channel access rights for the entire transmission duration. This eliminates the need for continuous LBT checks during data transmission, maintaining interference avoidance while significantly improving communication efficiency
Solution Approach 2:
Once the transmitter successfully accesses the channel through LBT, it maintains continuous transmission without interruption or repeated LBT checks. This continuous useful action maximizes productivity while the preliminary LBT ensures reliability, resolving the contradiction between interference avoidance and communication efficiency
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A transmitter may include an interference avoidance preamble in a wireless transmission. The interference avoidance preamble may identify resources for transmitting an interference avoidance request associated with the wireless transmission. A receiver may experience interference between the wireless transmission and another wireless transmission, and the receiver may transmit the interference avoidance request using the resources identified in the interference avoidance preamble. The transmitter may receive the interference avoidance request and, in response, may enable an interference avoidance mechanism, for example, a listen before talk (LBT) procedure, a frequency-division multiplexing (FDM) scheme, a time-division multiplexing (TDM) scheme, a spatial multiplexing scheme, or a combination.