Multi-TRP Mobility Procedures With Limited Reference Signals
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing the diverse requirements of 5G networks, including support for improved broadband performance, industrial control and communications, vehicular applications, and massive machine-type communications, particularly in terms of spectrum flexibility, latency, reliability, and mobility for varying use cases.
Innovation Solution
A 5gFLEX design is proposed, which incorporates flexible radio access technology that supports multiple frequency ranges, dynamic duplexing methods, variable TTI lengths, and coexistence of different waveforms like OFDM-OQAM and UF-OFDM, enabling efficient spectrum utilization and aggregation across fragmented bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional handover procedures are used among multiple coordinated TRPs, then connectivity is maintained, but latency increases and signaling overhead increases
Solution Approach 1:
The WTRU performs measurements on reference signals from multiple TRPs in advance and maintains measurement results for quick decision-making during handover events, eliminating the need for extensive real-time signaling
Solution Approach 2:
The WTRU autonomously determines the target TRP for handover based on pre-collected measurement data and current channel conditions, making handover decisions without extensive network intervention and reducing signaling overhead
2Reliability
If random access procedures are performed with multiple TRPs using separate resources, then connection establishment is reliable, but signaling overhead increases
Solution Approach 1:
The WTRU transmits a single random access preamble that can be detected by multiple TRPs simultaneously using the same time-frequency resources, merging what would traditionally be separate access procedures into one unified transmission
Solution Approach 2:
The random access resources are designed to serve multiple TRPs universally, allowing the same preamble transmission to be received and processed by any TRP in the coordinated set, eliminating the need for TRP-specific resources
3Reliability
If the WTRU continuously monitors all coordinated TRPs, then mobility performance is improved, but power consumption increases
Solution Approach 1:
The WTRU performs full measurements on a subset of TRPs based on current needs and channel conditions rather than continuously monitoring all TRPs, using partial measurement action to maintain mobility performance while reducing power consumption
Solution Approach 2:
The WTRU performs measurements on coordinated TRPs periodically or event-triggered rather than continuously, updating its knowledge of TRP conditions at intervals that maintain mobility performance while significantly reducing average power consumption
Data Source
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AI summary
Methods to perform, maintain and report measurements on a transmission-reception point (TRP) using limited reference signal transmission are described herein. The mobility measurement reports may utilize physical channels. Methods to obtain measurements on neighbor TRPs using limited RS transmissions are also described herein. Random-Access procedures to enable the addition of a neighbor TRP or handover without requiring higher layer signaling (and possibly without an interface between source and target TRP) are also described herein. New triggers to perform RA in order to decrease handover latency are also described herein. Wireless Transmit/Receive Unit (WTRU) behavior upon receiving RAR from multiple possible TRPs are also described herein. For example, a WTRU may store RAR information and use it later in an interrupted RA procedure.