RLC PDU Transmission Sequencing for Wireless Latency Reduction
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Solution Overview
Problem
The increasing number of user equipment (UEs) and the amount of data and control information in wireless communication systems pose challenges for base stations (BS) to efficiently manage limited radio resources, particularly in reducing delay and latency, which is critical for performance in various applications.
Innovation Solution
A communication device and method that construct and transmit radio link control (RLC) protocol data units (PDUs) by prioritizing and sequencing RLC service data units (SDUs) with lower sequence numbers for initial transmission, using a poll to trigger status reporting, and retransmitting PDUs with higher sequence numbers when necessary, to optimize resource utilization and reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station transmits all M RLC PDUs including all M RLC SDUs, then the complete data is delivered to the UE, but the transmission delay increases and resource efficiency decreases
Solution Approach 1:
The base station performs preliminary actions by constructing all M RLC PDUs in advance but only submits L PDUs (where L < M) with the lowest sequence numbers to the MAC layer for immediate transmission. The remaining M-L PDUs are held in buffer and retransmitted later when resources are available or upon receiving a poll signal, thus reducing initial transmission delay while ensuring complete data delivery
Solution Approach 2:
The transmission of M RLC PDUs is segmented into two phases: first transmission of L critical PDUs with lowest sequence numbers, and subsequent retransmission of the remaining M-L PDUs. This segmentation allows the system to prioritize essential data while deferring less critical transmissions, balancing reliability and delay
2Reliability
If the base station transmits all M RLC PDUs, then all data is sent to the UE, but the utilization of limited radio resources becomes inefficient
Solution Approach 1:
The base station prepares all M RLC PDUs in advance but selectively submits only L PDUs to the MAC layer for immediate transmission, holding the remaining M-L PDUs in buffer. This preliminary filtering action ensures that only the most critical data (lowest sequence numbers) consumes radio resources immediately, improving resource utilization efficiency while maintaining complete data delivery
Solution Approach 2:
Instead of transmitting all M RLC PDUs equally, the system applies partial action by transmitting only L critical PDUs in the first opportunity. The remaining M-L PDUs are transmitted partially in subsequent opportunities based on resource availability and poll signals, optimizing radio resource utilization while ensuring complete data delivery
3Speed
If the base station transmits RLC PDUs with higher sequence numbers first, then advanced data is delivered, but the sequence integrity and reliability of data reception are compromised
Solution Approach 1:
The system inverts the conventional approach by transmitting RLC PDUs with the lowest sequence numbers first rather than highest sequence numbers. This inversion ensures that data is delivered in the correct sequence order, maintaining sequence integrity and reliability, while still achieving efficient transmission by sending L critical PDUs immediately and deferring the rest
Data Source
AI summary
A communication device, processing device or method constructs M RLC PDUs including M RLC SDUs, respectively, where M is larger than 1; submits, for a transmission opportunity, only L RLC PDUs for L RLC SDUs with lowest L SNs among the M RLC PDUs to a MAC layer, where L<M and the L RLC PDUs include a first RLC PDU having a poll to trigger status reporting at a receiving device; transmits the L RLC PDUs to the receiving device; constructs a second RLC PDU including a second RLC SDU having a highest SN among SNs of RLC SDUs submitted to the MAC layer, when the poll retransmission timer started upon submitting the first RLC PDU having the poll expires and no new RLC SDU or RLC SDU segment can be transmitted.