Timing Advance Offset for MU-MIMO in IAB
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Solution Overview
Problem
Current wireless communication systems face challenges in aligning timing advance for both backhaul and access links in integrated access and backhaul systems, which is crucial for supporting Multiple User Multiple Input Multiple Output (MU-MIMO) in next-generation wireless networks, as existing synchronization schemes primarily focus on downlink timing and do not effectively align uplink subframes across different propagation delays.
Innovation Solution
An enhanced timing advance scheme is introduced that modifies the timing advance offset for access link transmissions by offsetting it with the timing advance of the backhaul link, ensuring that access link and backhaul link transmissions arrive simultaneously, thereby enabling MU-MIMO gains at the receiver side by applying a formula-based TA configuration that accounts for the distance and parent node timing advances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing synchronization schemes focus on downlink timing, then downlink timing alignment is improved, but uplink subframe alignment across different propagation delays deteriorates
Solution Approach 1:
The patent applies different timing advance values to different uplink transmissions based on their specific characteristics. Each uplink subframe is assigned a tailored TA value that accounts for its propagation delay, allowing precise alignment of uplink subframes while maintaining downlink timing focus. This local optimization resolves the contradiction by treating each transmission individually rather than applying a uniform approach.
Solution Approach 2:
The patent dynamically adjusts timing advance parameters for uplink transmissions based on measured propagation delays and network conditions. By changing the TA parameter values adaptively, the system maintains both downlink timing alignment precision and uplink subframe alignment reliability, resolving the contradiction through parameter optimization.
2Loss of time
If timing advance offset is modified to align access and backhaul link transmissions, then simultaneous arrival at receiver is improved, but system complexity increases
Solution Approach 1:
The patent calculates and configures timing advance values in advance before actual transmissions occur. The network determines appropriate TA offsets based on measured propagation delays and pre-configures them for upcoming uplink transmissions. This preliminary configuration ensures simultaneous arrival of access and backhaul link transmissions without requiring complex real-time adjustments during transmission.
Solution Approach 2:
The patent introduces a network controller as an intermediary that manages timing advance configurations. The controller receives propagation delay measurements, calculates appropriate TA offsets, and distributes them to relevant nodes. This intermediary simplifies the overall system complexity by centralizing the complex timing calculations and coordination functions.
3Measurement precision
If formula-based TA configuration accounts for distance and parent node timing advances, then MU-MIMO performance is improved, then timing alignment precision is improved, but calculation complexity increases
Solution Approach 1:
The patent segments the timing advance calculation into distinct components: a base TA value derived from distance measurements and adjustment factors derived from parent node timing advances. This segmentation allows the system to apply precise formula-based calculations while managing complexity through modular computation and reuse of pre-calculated values.
Data Source
AI summary
Various embodiments disclosed herein provide for an enhanced timing advance scheme to support MU-MIMO in an integrated access and backhaul system. The timing advance scheme disclosed herein aligns the arrival time between backhaul links and access links to enable MU-MIMO gain at the receiver side. In the integrated access and backhaul system, which comprises distributed nodes, the timing advance offset for an access link transmission (a transmission to a node further away in hops from the core network, or to a user equipment device) can be modified by offsetting it with the timing advance of the backhaul link (e.g., from a parent node). This enables the arrival time for transmissions, both access link transmissions from the UE or child node, and backhaul link transmissions from a parent node to arrive at the same time.