OTFS PDCCH Segmentation for Doppler Robustness
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing the physical downlink control channel (PDCCH) communications, particularly in handling orthogonal time frequency space (OTFS) modulation, which is affected by high residual frequency offset and large Doppler spread.
Innovation Solution
The implementation of a user equipment (UE) and base station configuration that includes receiving and transmitting PDCCH communications with OTFS precoding in a delay-Doppler domain, along with a first stage PDCCH communication to indicate whether OTFS modulation is scheduled, allowing for selective buffering of time domain samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If OTFS modulation is applied to PDCCH communications, then robustness against high residual frequency offset and large Doppler spread is improved, but device complexity increases
Solution Approach 1:
The PDCCH communications are segmented into two stages: first stage PDCCH communications transmitted without OTFS precoding for basic control information, and second stage PDCCH communications transmitted with OTFS precoding for additional robustness. This segmentation allows the system to apply OTFS modulation selectively rather than universally, reducing overall complexity while maintaining robustness where needed.
Solution Approach 2:
OTFS precoding is applied partially rather than completely to all PDCCH communications. The base station determines based on channel conditions and UE capabilities whether to apply OTFS precoding to second stage PDCCH communications, applying the complex modulation only when necessary to achieve the required robustness level.
2Reliability
If the UE continuously monitors for PDCCH communications, then communication reliability is improved, but power consumption increases
Solution Approach 1:
The UE monitors PDCCH communications in a periodic manner rather than continuously. The UE wakes up at scheduled intervals to monitor first stage PDCCH communications, processes them to determine if second stage communications are present, and can enter sleep mode between monitoring occasions. This periodic monitoring maintains communication reliability while significantly reducing power consumption compared to continuous monitoring.
3Measurement precision
If the UE buffers time domain samples for OTFS modulation block, then decoding accuracy is improved, but memory requirements and processing overhead increase
Solution Approach 1:
The UE applies different processing quality to different stages of PDCCH communications. For first stage PDCCH communications, the UE uses standard processing without extensive buffering. For second stage PDCCH communications with OTFS precoding, the UE buffers time domain samples associated with the OTFS modulation block to improve decoding accuracy. This local quality approach applies high-quality processing only where needed rather than uniformly across all communications.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a base station, a configuration of a control region in a delay-Doppler domain. The UE may receive, from the base station, a physical downlink control channel (PDCCH) communication with orthogonal time frequency space (OTFS) precoding. The UE may decode the PDCCH communication with OTFS precoding based at least in part on the configuration of the control region in the delay-Doppler domain. Numerous other aspects are described.