Flexible Frame Structure for Sub-Frame Retransmission in 5G URLLC
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Solution Overview
Problem
Current 5G wireless systems face challenges in achieving high reliability for decoding control and data information, particularly in ultra-reliable low-latency communications (URLLC), as existing frame structures require retransmissions to occur after at least one sub-frame duration, potentially violating latency constraints.
Innovation Solution
A flexible frame structure is introduced that enables retransmission of control and data information within a single sub-frame, allowing for immediate correction of decoding errors and efficient data transmission, even in cases where control information is missed, by incorporating special symbols for retransmission during the same sub-frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retransmission is performed after at least one sub-frame duration as in existing frame structures, then decoding reliability is improved, but latency constraint is violated
Solution Approach 1:
The patent applies dynamics by making the frame structure flexible and adaptable. Specifically, it allows the retransmission timing to be dynamic rather than fixed at one sub-frame duration. The base station can determine retransmission timing based on channel conditions and decoding status, enabling faster retransmission when possible while maintaining reliability. This is evident in the flexible frame structure where retransmission can occur within the same sub-frame or at optimized intervals, rather than following a rigid timing schedule.
Solution Approach 2:
The patent implements preliminary action by performing retransmission preparation and channel assessment before the standard sub-frame duration elapses. The base station monitors decoding status and prepares retransmission resources in advance, allowing it to execute retransmission sooner when conditions permit. This proactive approach enables the system to achieve reliable delivery without waiting for the full sub-frame duration, thus reducing latency while maintaining decoding reliability.
2Loss of time
If retransmission occurs in the same sub-frame, then latency requirement is met, but control information may be missed
Solution Approach 1:
The patent heavily utilizes feedback mechanisms to resolve this contradiction. The base station receives feedback about decoding status from user equipment and uses this information to determine whether retransmission is necessary. The flexible frame structure incorporates feedback loops where the base station monitors whether control information was successfully received and decoded, then adjusts retransmission timing accordingly. This feedback-driven approach ensures that retransmission only occurs when needed, maintaining reliability while minimizing latency.
Solution Approach 2:
The patent makes the retransmission process dynamic by allowing the timing and necessity of retransmission to be determined in real-time based on channel conditions and decoding status. Rather than blindly retransmitting at fixed intervals, the system dynamically adjusts retransmission behavior based on actual system state. This dynamic approach allows the system to meet latency requirements by avoiding unnecessary retransmissions while ensuring reliability when decoding failures occur.
3Loss of time
If flexible frame structure with same-subframe retransmission is implemented, then latency constraint is satisfied, but system complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the frame structure into distinct functional segments that can be independently managed. The flexible frame structure is segmented into control information regions, data regions, and retransmission regions, allowing each to be optimized independently. This segmentation simplifies the overall complexity by providing clear boundaries and roles for different frame components, making the system more manageable despite the increased flexibility required for same-subframe retransmission.
Solution Approach 2:
The patent implements universality by designing a flexible frame structure that can serve multiple functions within the same framework. The same frame structure handles both initial transmission and retransmission, and can adapt to different latency requirements and channel conditions. This multi-functional design reduces overall system complexity compared to having separate rigid structures for different transmission scenarios, as the flexible structure unifies multiple operations under a single adaptable framework.
Data Source
AI summary
Apparatus, methods, systems, and computer program products for flexible frame structure in control information delivery are provided. An exemplary embodiment provides an apparatus comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to receive, at a first device, a sub-frame comprising at least one symbol transmitted over a network from a network node, wherein the at least one symbol comprising control information to the first device, and transmit, from the first device, scheduled data towards the network node based on the control information.