Relay Node Timing Synchronization for In-Band Interference Reduction
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Solution Overview
Problem
In-band relay nodes in wireless communication systems face limitations in half-duplex mode, leading to increased interference and data buffer lengths, which result in decreased data-rate performance and delays due to the inability to send and receive on the same channel simultaneously.
Innovation Solution
A method and apparatus for synchronizing wireless communication between a main unit and two radio units, where the main unit computes timing differences for signal propagation between the radio units to align the access link and backhaul link, avoiding interference by adjusting transmission timing without reserving special OFDM symbols for switch times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If in-band relay nodes operate in half-duplex mode to share the same spectrum for backhaul and access links, then spectrum efficiency is improved, but interference increases and data-rate performance decreases
Solution Approach 1:
The patent changes the timing parameter by computing propagation delays and adjusting transmission timing offsets. The main unit calculates the time difference for signals to travel between radio units and adjusts the transmission timing accordingly, transforming the half-duplex operation from a source of interference into a synchronized communication scheme that maintains spectrum efficiency while eliminating self-interference through precise timing control
2Adaptability or versatility
If in-band relay nodes operate in half-duplex mode, then spectrum resources are efficiently utilized, but data buffer lengths increase causing delays
Solution Approach 1:
The patent applies preliminary action by computing propagation delays in advance and pre-adjusting transmission timing before actual data transmission occurs. The main unit calculates the timing offset based on the distance between radio units and configures the transmission schedule accordingly, allowing the relay node to operate in half-duplex mode without accumulating data buffers or introducing delays, as the timing is optimized beforehand
3Object-generated harmful factors
If transmission timing is adjusted to align access link and backhaul link, then interference is reduced, but timing synchronization complexity increases
Solution Approach 1:
The patent applies self-service by having the main unit automatically compute propagation delays using the known distances between radio units and the speed of light, then autonomously adjust transmission timing without requiring complex external synchronization protocols. The system uses its own geometric configuration information to self-correct timing offsets, reducing interference while keeping the synchronization mechanism simple and self-contained
Data Source
AI summary
Relay node (110), main unit (113) for a relay node and method in a main unit (113) for a relay node (110), which main unit (113) is connectible to a first radio unit (111) and to a second radio unit (112), for synchronising wireless communication over the second radio unit (112) with wireless communication over the first radio unit (111). The method comprises transmitting a synchronisation signal at the second radio unit (112), receiving the signal at the first radio unit (111), to compute a first timing difference corresponding to the signal propagation time and to adjust the downlink transmission timing at the second radio unit (112) according to the first timing difference. Similar signalling, estimation of timing difference and adjustment is made for signals to be received from the user equipment (130) at the second radio unit (112).