Paging and RAR Scheduling for Low-Cost UEs
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Solution Overview
Problem
Current paging and random access response (RAR) scheduling in LTE systems are not optimized for low-cost user equipment (UEs) with limited bandwidth, leading to high power consumption and resource inefficiencies, particularly in scenarios requiring repeated transmissions such as extreme coverage areas and Machine-Type Communication (MTC).
Innovation Solution
The proposed solution involves separate scheduling and transmission of system information-paging (SI-paging) and call-paging using distinct DCI formats, with SI-paging carrying value tags and bitmaps to indicate updates, and RAR scheduling based on UE coverage enhancement levels, allowing for efficient resource allocation and reduced power consumption by grouping UEs with similar characteristics and using repetition numbers for enhanced coverage modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If separate scheduling and transmission of SI-paging and call-paging is implemented, then power consumption and resource overhead are reduced, but device complexity increases
Solution Approach 1:
The paging procedure is segmented into two separate DCI formats: SI-Paging-DCI for system information paging and Call-Paging-DCI for call paging. This segmentation allows the UE to selectively decode only the relevant DCI format based on its current state and requirements, reducing overall power consumption and resource overhead despite the increased complexity of handling multiple DCI formats.
2Reliability
If RAR scheduling is based on CE level with repetition numbers, then coverage is improved in extreme scenarios, but resource overhead increases
Solution Approach 1:
The RAR scheduling is optimized by applying different repetition numbers based on the UE's CE level. UEs in extreme coverage scenarios (higher CE levels) are allocated more repetitions and appropriate RAR modes, while UEs in normal coverage use fewer repetitions. This local quality approach ensures reliable coverage for vulnerable UEs without unnecessarily increasing resource overhead for all UEs.
3Productivity
If multiple RAR mode is used for plurality of UEs, then resource efficiency is improved, but measurement precision for individual UE decreases
Solution Approach 1:
The system dynamically selects between single RAR mode and multiple RAR mode based on the number of UEs in the random access procedure and their CE levels. When multiple UEs are detected, the system switches to multiple RAR mode to improve resource efficiency. The selection of appropriate RAR modes for different CE levels ensures that measurement precision is maintained for individual UEs while achieving overall resource efficiency.
Data Source
AI summary
Methods and apparatus are provided for paging and random access response (RAR) scheduling and downlink control information (DCI) for a user equipment (UE). In one novel aspect, an SI-paging and a call-paging are transmitted separately, and scheduled by SI-Paging-DCI and call-Paging-DCI respectively. In one embodiment, a special PO is introduced for stand-alone SI-Paging scheduled by SI-Paging-DCI, and the special PO is different from the PO for call-Paging. In another novel aspect, SI-Paging is scheduled together with call-paging in the same PDSCH scheduled by call-Paging-DCI. In one embodiment, the SI-paging carries a value tag and a bitmap, wherein the value tag indicates whether any SI updates, and the bitmap indicates which one or more SIs updates. In another embodiment, the SI-Paging carries several valuetags, and the number of valuetag corresponds to the number of SI. The UE compares a current valuetag to a stored valuetag to verify whether a SI changes.