Uplink Synchronization Signaling for Cooperative UE Timing Advance
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Solution Overview
Problem
Devices with limited antenna resources, such as AR glasses or watches, face challenges in achieving MIMO gains due to high antenna correlation and propagation delays when cooperating with network entities, leading to asynchronous uplink transmissions that violate the cyclic prefix.
Innovation Solution
Cooperative communication between an anchor UE and a companion UE, where the network entity provides timing information to synchronize uplink transmissions using Timing Advance (TA) values, ensuring that signals from both UEs arrive at the network entity within the cyclic prefix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If devices with limited antenna resources cooperate with network entities, then device mobility and form factor are improved, but antenna correlation and propagation delays increase causing asynchronous uplink transmissions
Solution Approach 1:
The network entity performs preliminary timing measurements by receiving reference signals from both the first UE and the second UE before actual data transmission. Based on these measurements, the network entity calculates timing advance values and provides timing information to the first UE in advance, enabling the first UE to pre-adjust its transmission timing and ensure synchronous arrival of signals from both UEs at the network entity.
2Reliability
If Timing Advance adjustments are applied to synchronize uplink transmissions, then transmission synchronization is improved, but device complexity increases due to coordinated TA adjustments
Solution Approach 1:
The network entity acts as an intermediary that centralizes the timing coordination function. Instead of each UE independently calculating and adjusting its own timing, the network entity measures propagation delays, calculates appropriate timing advance values, and provides timing information to the UEs. This intermediary approach simplifies the complexity by centralizing the coordination burden at the network side while maintaining synchronization at the uplink transmissions.
3Device complexity
If signals from multiple UEs are transmitted asynchronously, then device simplicity is maintained, but MIMO gains and system throughput are reduced
Solution Approach 1:
The network entity continuously monitors the timing of uplink transmissions from multiple UEs and provides feedback in the form of timing information. This feedback mechanism enables the UEs to adjust their transmission timing based on actual network conditions and propagation delays, ensuring that signals arrive synchronously at the network entity. This feedback-driven synchronization maintains simple device operation while maximizing MIMO gains and system throughput.
Data Source
AI summary
Some examples of the techniques described herein may help to ensure that uplink transmissions from two separate UEs (e.g., an anchor UE and an companion UE) reach a network within a cyclic prefix. In some approaches, a network entity may determine timing information based on signaling with an anchor UE and a companion UE. The network entity may output the timing information to the anchor UE or companion UE, which may enable the anchor UE or companion UE to synchronize transmissions to the network entity. The anchor UE may utilize the timing information to time a sidelink transmission (for relay to the network entity) and an uplink transmission (to the network entity) such that the transmissions may reach the network entity at approximately the same time (e.g., within a cyclic prefix).