Coordinating Cell Data Transmission for URLLC Reliability
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Solution Overview
Problem
The 5G mobile communications system faces challenges in achieving the required reliability of 99.999% within 1 ms latency for URLLC services, especially for user equipment at the cell edge with poor signal-to-noise ratios, where multiple transmissions are needed, but are limited by the short scheduling unit duration.
Innovation Solution
A data transmission method where user equipment receives data from a serving cell and a coordinating cell, with the coordinating cell assisting the serving cell in retransmitting data based on decoding results, allowing flexible resource allocation and multiple access points to improve reliability within the stringent latency requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple transmissions are performed to achieve 99.999% reliability, then transmission reliability is improved, but transmission latency increases beyond the 1 ms requirement
Solution Approach 1:
The patent segments the transmission task across multiple access network devices (serving cell and coordinating cells). Instead of one device performing multiple retransmissions sequentially, the data is divided and transmitted simultaneously through multiple devices, achieving both reliability and low latency by parallelizing the transmission path
Solution Approach 2:
The patent introduces a spatial dimension to the transmission system by involving multiple access network devices at different locations (serving cell and coordinating cells). This transforms the problem from temporal repetition (multiple transmissions over time) to spatial diversity (multiple transmissions across different devices simultaneously), thereby achieving reliability without increasing latency
2Loss of time
If a short scheduling unit of 0.125 ms is used to meet latency requirements, then transmission latency is reduced, but the maximum number of transmissions within 1 ms is limited to 8
Solution Approach 1:
The patent merges the transmission capabilities of multiple access network devices (serving cell and coordinating cells) to effectively increase the number of available transmission opportunities. By combining resources from multiple devices, the system can perform more transmissions within the 1 ms window than a single device could achieve alone with 0.125 ms scheduling units
Solution Approach 2:
The patent adds a spatial dimension to transmission resources by utilizing multiple access network devices. This allows the system to overcome the limitation of 8 transmissions per 1 ms imposed by single-device time-division multiplexing, achieving higher effective transmission counts through spatial parallelism
3Reliability
If the second access network device always transmits data to the UE, then transmission reliability is improved, but resource waste occurs when the UE has already decoded the data successfully
Solution Approach 1:
The patent implements a feedback mechanism where the UE sends decoding results (ACK/NACK signaling) back to the access network devices. The second access network device uses this feedback to determine whether retransmission is necessary, transmitting data only when the decoding result is NACK, thereby avoiding unnecessary transmissions and resource waste while maintaining reliability
Solution Approach 2:
The patent makes the transmission behavior of the second access network device dynamic rather than static. Instead of always transmitting or never transmitting, the device adjusts its transmission decisions based on real-time feedback from the UE, optimizing resource utilization while ensuring reliability when needed
Data Source
AI summary
This application relates to the field of wireless communications technologies, and in particular, to a data transmission method, an apparatus, and a system. Random access resource information: receiving, by user equipment UE, data from a first access network device to which a serving cell belongs; sending, by the UE, a decoding result of the data to the first access network device and a second access network device to which a coordinating cell belongs; and if the decoding result is negative acknowledgment NACK signaling, receiving, by the UE from the first access network device, the data that is retransmitted, and receiving, by the UE, the data from the second access network device.