Semi-Persistent Scheduling for Autonomous Uplink in Unlicensed Spectrum
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Solution Overview
Problem
Current wireless cellular communication systems, particularly in unlicensed spectrum, face performance degradation due to double Listen-Before-Talk (LBT) requirements in scheduled systems like LTE, leading to uplink starvation when coexisting with non-scheduled systems like Wi-Fi, which affects uplink transmission efficiency.
Innovation Solution
Implementing autonomous uplink (AUL) transmission mechanisms, including semi-persistent scheduling (SPS) and new DCI formats, to improve uplink performance by allowing flexible activation and release of resources, reducing latency and overhead, and enabling efficient coexistence with other wireless systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If scheduled uplink transmission with double LBT is used, then system compatibility with LTE is maintained, but uplink transmission efficiency deteriorates due to uplink starvation when coexisting with Wi-Fi
Solution Approach 1:
The patent implements dynamic switching between scheduled uplink transmission and autonomous uplink transmission modes. The system can adaptively select the appropriate transmission mode based on channel conditions and coexistence requirements with Wi-Fi, thereby resolving the contradiction between transmission efficiency and reliability. This dynamic approach allows the system to achieve high uplink transmission efficiency when using autonomous mode while maintaining compatibility with LTE scheduled mode when needed.
2Productivity
If autonomous uplink transmission is implemented, then uplink transmission efficiency is improved, but device complexity increases due to new DCI formats and activation/release mechanisms
Solution Approach 1:
The patent designs DCI format 0A to serve multiple functions: it can indicate both scheduled uplink transmissions and autonomous uplink transmissions, and can convey activation and release commands for semi-persistent scheduling. By making this existing DCI format multi-functional, the patent avoids introducing entirely new DCI formats, thereby improving uplink transmission efficiency while minimizing the increase in device complexity.
Solution Approach 2:
The autonomous uplink transmission mechanism allows the UE to autonomously activate and release uplink resources based on pre-configured parameters and DCI indications, without requiring continuous network scheduling. This self-service capability reduces the signaling overhead and simplifies the interaction between network and device, thereby improving transmission efficiency while keeping device complexity manageable.
3Loss of time
If semi-persistent scheduling with autonomous activation is used, then latency is reduced, but overhead increases due to activation and release signaling
Solution Approach 1:
The patent performs preliminary configuration of uplink transmission parameters through RRC signaling before actual transmission occurs. The network pre-configures the UE with all necessary parameters for autonomous uplink transmission, including resource allocation, modulation and coding schemes, and activation conditions. This preliminary action eliminates the need for real-time signaling during transmission, thereby reducing latency while managing signaling overhead efficiently.
Solution Approach 2:
The patent uses parameter changes in existing DCI fields to convey activation and release commands for semi-persistent scheduling. By interpreting existing DCI format 0A fields in different contexts (e.g., specific values of resource allocation fields indicating activation vs. release), the system can switch between transmission modes without adding dedicated signaling bits, thus reducing overhead while maintaining low latency.
Data Source
AI summary
Described is an apparatus of a User Equipment (UE). The apparatus may comprise a first circuitry and a second circuitry. The first circuitry may be operable to process a first Downlink Control Information (DCI) format 0A transmission indicating a semi-persistent scheduling (SPS) activation. The first circuitry may also be operable to process a second DCI format 0A transmission indicating an SPS release. The second circuitry may be operable to generate one or more Uplink (UL) transmissions for an unlicensed spectrum of the wireless network after the SPS activation and before the SPS release in accordance with a configured schedule.