Supplementary Uplink Carrier Selection in Wireless Systems
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing supplementary uplink (SUL) configurations, particularly in high-frequency environments where regular uplink (RUL) coverage is inadequate, leading to suboptimal cell selection and handover processes.
Innovation Solution
The implementation of supplementary uplink (SUL) configurations that allow Wireless Transmit/Receive Units (WTRUs) to autonomously switch between RUL and SUL based on specific conditions, such as downlink reference signal received power (DL-RSRP) thresholds, and utilize semi-persistent scheduling resources, while also considering radio resource control messages and radio link failure scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If WTRU uses regular uplink (RUL) for communication, then device complexity is reduced, but uplink coverage and reliability deteriorate in high-frequency environments
Solution Approach 1:
The patent implements dynamic switching between RUL and SUL based on real-time conditions. The WTRU autonomously selects the appropriate uplink carrier by evaluating DL-RSRP measurements against thresholds, enabling adaptive operation that maintains reliability without requiring complex manual configuration. The system dynamically adjusts its behavior based on environmental conditions.
Solution Approach 2:
The WTRU performs autonomous cell selection and uplink carrier selection without requiring network intervention. By measuring DL-RSRP and comparing it against stored thresholds, the WTRU independently determines whether to use RUL or SUL, reducing the need for complex network management while ensuring optimal uplink performance.
2Reliability
If WTRU performs frequent handovers between RUL and SUL, then uplink coverage is optimized, but handover frequency and system complexity increase
Solution Approach 1:
The system employs feedback mechanisms where the WTRU continuously measures DL-RSRP and compares it against predefined thresholds to determine the appropriate uplink carrier. This feedback loop enables automatic adaptation to changing radio conditions, optimizing coverage while keeping handover management simple through objective, threshold-based decision criteria.
Solution Approach 2:
The patent uses parameter changes in the form of threshold-based decision making. By changing the selection parameter from fixed RUL to conditional selection based on DL-RSRP threshold comparisons, the system achieves optimized coverage. The thresholds act as simple change points that trigger carrier switching without complex handover coordination.
3Reliability
If WTRU configures both SUL and RUL simultaneously, then uplink reliability is improved, but cell selection and handover procedures become more complex
Solution Approach 1:
The patent segments the uplink selection process into distinct phases: cell selection phase (where SUL cells are identified using modified criteria) and uplink carrier selection phase (where RUL/SUL choice is made based on DL-RSRP thresholds). This segmentation simplifies the overall procedure by dividing the complex decision-making into manageable stages with clear decision points.
Solution Approach 2:
The system dynamically adapts cell selection and handover procedures based on whether SUL is configured and available. The WTRU modifies its behavior dynamically by applying different cell suitability criteria when SUL is present, and by switching between RUL and SUL based on real-time DL-RSRP measurements, thereby managing complexity through adaptive rather than static procedures.
Data Source
AI summary
Supplementary uplink (SUL) may be used in wireless systems. Cell suitability criteria may be provided for cells configured with SUL. A Wireless Transmit/Receive Unit (WTRU) may receive paging with an indication of a carrier (e.g., SUL or regular uplink (RUL) in which to initiate part or all of an initial access. A WTRU that may be performing response-driven paging may provide (e.g. explicit) beam information for beamforming of a paging message on a non-beamformed SUL. A handover (HO) procedure (e.g., carrier selection, configuration handling, HO failure, etc.) may be provided for a WTRU with a configured SUL. A WTRU may request a change of a configured UL. A WTRU may (e.g., autonomously) perform a switch to a different (e.g., configured) uplink, for example, when one or more conditions may be met (e.g., conditional switch). Semi-persistent scheduling (SPS) resources/configuration may be relocated from a first UL to a second UL.