Timer-Based Transmission Delay Reduction on Shared Carriers
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Solution Overview
Problem
In wireless communication networks, the use of timers to trigger message transmissions and channel access procedures like LBT before using unlicensed carriers leads to transmission delays and network inefficiencies, as the full duration of the channel access procedure often delays timer-triggered messages.
Innovation Solution
A communication device initiates a first channel access procedure before the expiration of a timer that triggers a message transmission, allowing for earlier transmission if the carrier is available, and potentially initiating a second channel access procedure if the first ends before the timer expires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a device performs a channel access procedure (LBT) before transmitting a timer-triggered message on an unlicensed carrier, then fair co-existence with other radio access technologies is achieved, but the transmission delay increases by the full duration of the channel access procedure
Solution Approach 1:
The device initiates the channel access procedure before the timer expires, performing the LBT in advance of the actual transmission need. This allows the device to know ahead of time whether the channel will be available, enabling it to prepare the message for immediate transmission once the procedure completes, thereby reducing the effective delay while maintaining fair access to the unlicensed carrier
2Measurement precision
If a device waits for timer expiration before initiating channel access procedure, then transmission timing is precise, but network efficiency decreases due to unavoidable delays
Solution Approach 1:
The channel access procedure is initiated before the timer expires, allowing the device to perform the LBT in advance. The device then monitors the completion of the procedure and transmits the message at the appropriate time, balancing timing precision with network efficiency by overlapping the channel access procedure with the timer countdown
3Adaptability or versatility
If a device uses a variable-length contention window for LBT, then adaptability to channel conditions is improved, but transmission delay becomes harder to compensate for
Solution Approach 1:
By initiating the channel access procedure before the timer expires, the device creates a buffer that can accommodate the variable duration of the LBT with adaptive contention windows. The device can then calculate the actual delay incurred and compensate accordingly, making the system adaptable to varying channel conditions while maintaining predictable transmission timing
Data Source
AI summary
A method for reducing transmission delays, implemented in a communication device, includes starting (502) a first timer. An expiration (504) of the first timer corresponds to a desired transmission time for a first message. The method also includes, before the expiration of the first timer, starting (504) a first channel access procedure of one or more channel access procedures, and determining (508), using the one or more channel access procedures, whether a shared carrier is available for transmission after the expiration of the first timer. The method also includes, based on whether the shared carrier is available for transmission after the expiration of the first timer (510), either transmitting (512) or not transmitting (514) the first message to another communication device via the shared carrier.