Wireless TXOP Preemption Using RTS/CTS for Priority Traffic
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Solution Overview
Problem
In conventional wireless communication technologies, high-priority access category (AC) traffic experiences excessive latency due to competing for the medium during a transmission opportunity (TXOP) burst of lower-priority AC traffic, leading to inefficient resource allocation.
Innovation Solution
Implementing a preempt mechanism through an initiator apparatus that transmits a request to send (RTS) frame with a flag indicating whether a preempt operation is allowable during the TXOP duration, and suspending the TXOP if a clear-to-send (CTS) frame is not received, along with utilizing short inter-frame spaces (SIFS) and abort frames to manage preempt operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high-priority AC traffic competes for the medium during a TXOP burst of lower-priority AC traffic, then medium access opportunity is maintained, but latency of high-priority AC traffic becomes too long
Solution Approach 1:
The patent applies preliminary action by having the initiator apparatus transmit an RTS frame before the actual data transmission to reserve the medium and establish TXOP parameters in advance. This preliminary reservation mechanism allows high-priority traffic to preemptively claim medium access rights, preventing delays while maintaining efficient resource allocation.
Solution Approach 2:
The patent implements dynamics by introducing a preemptable flag in the RTS frame that dynamically adjusts TXOP behavior based on priority conditions. When high-priority traffic detects a need to preempt, the system dynamically suspends the current TXOP burst and reallocates medium access, transforming the static TXOP mechanism into an adaptive one that responds to priority-based demands.
2Loss of time
If TXOP operation is suspended for preempt operations, then latency of high-priority traffic is reduced, but complexity of TXOP management increases
Solution Approach 1:
The patent uses the RTS frame as an intermediary mechanism that carries preempt indication information between apparatuses. This intermediary structure simplifies the preempt operation by encoding complex suspension decisions into a simple flag field, avoiding the need for complex negotiation protocols while enabling timely high-priority access.
Solution Approach 2:
The patent implements feedback through the CTS frame response mechanism. When the responder apparatus receives an RTS frame with preempt indication, it responds with a CTS frame that confirms the suspension decision. This feedback loop ensures coordinated TXOP management, reducing complexity by providing clear, unambiguous confirmation of the preempt state to all involved apparatuses.
Data Source
AI summary
An initiator apparatus is provided. The initiator apparatus may include a transceiver and a processor. The transceiver may be configured to perform wireless transmission and reception to and from a responder apparatus. The processor may be coupled to the transceiver. The processor may perform the following operations. The processor may transmit, via the transceiver, a request to send (RTS) frame to the responder apparatus for a transmission opportunity (TXOP) burst during a TXOP duration of a TXOP operation, wherein the RTS frame indicates whether a preempt operation is allowable during the TXOP duration. The processor may also determine to suspend the TXOP operation in the event that the initiator apparatus does not receive a clear-to-send (CTS) frame corresponding to the RTS frame from the responder apparatus.