PRS Scheduling Across Subcarrier Spacings to Avoid BWP Collisions
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Solution Overview
Problem
The lack of consistent numerology across different frequency ranges and carrier bandwidths in 5G NR networks causes difficulties for UEs in allocating sufficient resources to receive and decode positioning reference signals (PRS) simultaneously from multiple carrier bandwidths, particularly when PRSs are transmitted at the same time, leading to collisions and resource allocation challenges.
Innovation Solution
A mechanism is introduced to schedule PRS transmissions across different subcarrier spacings (SCSs) to avoid collisions, allowing UEs to receive and decode PRSs from multiple carrier bandwidths by staggering the transmission patterns to accommodate the capabilities of different UEs, ensuring minimal gaps between PRSs on different carrier bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PRS transmissions are aligned in time across different SL BWPs, then positioning accuracy is improved through simultaneous reception, but resource allocation becomes inefficient and collisions occur between PRS transmissions
Solution Approach 1:
The patent applies periodic action by configuring PRS transmissions with different periodicities for different SL BWPs. Instead of aligning all PRS transmissions simultaneously, the network configures different periodic intervals for PRS in first SL BWP versus second SL BWP, ensuring they do not collide while maintaining regular transmission patterns for positioning accuracy.
Solution Approach 2:
The patent uses preliminary action by pre-configuring different numerologies and periodicities for PRS transmissions in different SL BWPs before actual positioning operations. This advance configuration prevents collisions from occurring in the first place, allowing UEs to efficiently allocate resources without needing to handle dynamic collision resolution.
2Adaptability or versatility
If multiple PRS transmissions are scheduled with different periodicities, then resource flexibility is improved, but time alignment becomes inconsistent causing reception difficulties for UEs
Solution Approach 1:
The patent applies parameter changes by systematically varying the periodicity parameter for PRS transmissions across different SL BWPs. Each BWP is assigned a specific periodicity value that is a multiple of a base periodicity, allowing flexible resource allocation while maintaining predictable time relationships that UEs can handle.
Solution Approach 2:
The patent resolves the time alignment issue by introducing an additional dimension of control through numerology configuration. Different SL BWPs use different numerologies (subcarrier spacings) in combination with different periodicities, creating a two-dimensional resource space that provides flexibility while avoiding direct time conflicts.
3Device complexity
If PRS transmissions are staggered across different carrier bandwidths, then UE reception capability requirements are reduced, but positioning latency increases due to non-simultaneous reception
Solution Approach 1:
The patent applies dynamics by making the PRS transmission configuration adaptive to UE capabilities. The network can dynamically adjust which SL BWPs are activated for PRS transmission based on the receiving UE's receiver chain capabilities, allowing staggered transmissions for UEs with limited capabilities while enabling more simultaneous transmissions for advanced UEs.
Solution Approach 2:
The patent uses partial action by selectively activating only the necessary subset of SL BWPs for PRS transmission based on UE capabilities and positioning requirements. Instead of always transmitting on all available BWPs simultaneously, the system transmits on fewer BWPs when needed, reducing the burden on receiver chains while maintaining acceptable positioning performance.
Data Source
AI summary
A method for a UE is provided. The method transmits to a second UE a first PRS in a first set of symbols of a first slot of a first BWP and determines that a second PRS is to be transmitted in a second BWP that overlaps the first BWP in the time domain. The method receives information to determine whether the second UE is capable of successfully decoding the first and second PRSs. When the method determines that the second UE is not capable of such, the method modifies a scheduling of transmission of the second PRS by identifying a second set of symbols of a second slot of the second BWP for carrying the second PRS, such that a start of a first symbol of the second set of symbols follows an end of a second symbol of the first set of symbols in the time domain.