Inband Relay Node Self-Interference Elimination via Transmission Indication
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Solution Overview
Problem
Inband Relay Nodes (RN) in LTE mobile communication systems suffer from self-interference due to operating at the same frequency for both downlink and uplink transmissions, preventing simultaneous data reception and transmission across interfaces, leading to data loss.
Innovation Solution
A method is introduced to allocate specific time areas for transmission and reception using transmission indications, allowing RNs to manage time areas for signal transmission and reception on the Uu and Un interfaces without simultaneous operations, thereby avoiding self-interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an inband Relay Node operates at the same frequency for both downlink and uplink transmissions, then frequency resource utilization is improved, but self-interference occurs preventing simultaneous data reception and transmission
Solution Approach 1:
The patent implements dynamic time allocation where the RN can flexibly switch between reception and transmission modes based on traffic conditions. The transmission indication mechanism allows the RN to dynamically adjust its operation state, enabling it to receive downlink data from the BS and transmit uplink data to the BS at different time instances, thus resolving the self-interference issue while maintaining high frequency utilization.
Solution Approach 2:
The patent employs periodic time division where the RN alternates between reception periods and transmission periods. By using transmission indications to schedule these periodic actions, the RN ensures that downlink reception and uplink transmission do not occur simultaneously at the same frequency, eliminating self-interference while maintaining efficient resource usage through structured periodic operation.
2Object-generated harmful factors
If the RN cannot simultaneously receive and transmit data on the same frequency, then self-interference is avoided, but data loss occurs due to inability to handle concurrent communications
Solution Approach 1:
The patent uses transmission indications to preliminarily schedule and coordinate the RN's reception and transmission operations. By receiving advance indication of when transmission should occur, the RN can proactively prepare to switch modes and ensure that reception and transmission are properly time-separated, preventing data loss while avoiding self-interference through coordinated preliminary action.
Solution Approach 2:
The transmission indication mechanism establishes a feedback loop where the BS informs the RN about scheduled transmission opportunities. This feedback enables the RN to adjust its operation accordingly, ensuring that it does not transmit when reception is required and vice versa, thereby maintaining data integrity while avoiding self-interference through informed adaptive behavior.
3Productivity
If the RN uses the same frequency for Un and Uu interfaces, then spectrum efficiency is improved, but simultaneous operations on downlink and uplink become impossible
Solution Approach 1:
The patent implements dynamic time switching for the RN's interfaces, allowing the RN to flexibly alternate between Un interface reception, Un interface transmission, Uu interface reception, and Uu interface transmission based on traffic requirements and BS scheduling. This dynamic operation maintains spectrum efficiency by utilizing the same frequency for both interfaces while avoiding simultaneous conflicting operations through time-division coordination.
Solution Approach 2:
The patent employs periodic time-division multiplexing where the RN systematically alternates between different interface operations in scheduled periods. Transmission indications coordinate these periodic actions to ensure that when the RN is transmitting on the Un interface, it does not simultaneously receive on the Uu interface, and vice versa, thus maintaining spectrum efficiency while enabling sequential operation of both interfaces.
Data Source
AI summary
To prevent the self-interference of an inband relay node, a base station transmits a transmission indication on the downlink of a Un interface. Only when the base station receives an ACKnowledgment (ACK) signal in response to the transmission indication from the relay node, the base station transmits a Un interface downlink signal to the relay node in a specific time area. The time area allocated by the transmission indication may be a time area added to a statically allocated time area.