Relay Node Backhaul Sub-Frame RF Switching Delay
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Solution Overview
Problem
In wireless relay systems, particularly in Layer-3 (L3) relay systems, the RF transmission/reception switching time delay causes overlap between transmission and reception timing, leading to inefficiencies and interference, and existing designs struggle to minimize this delay while maintaining compatibility with conventional uplink and downlink sub-frame structures.
Innovation Solution
The proposed solution involves designing uplink and downlink backhaul sub-frame structures that account for RF transmission/reception switching time delays by employing techniques such as rate matching, multiplexing, and de-multiplexing, using predefined symbols as blanks at the beginning or end of sub-frames, and optimizing resource allocation to avoid interference and improve resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF transmission/reception switching is performed in L3 relay systems, then transmission and reception links are separated, but time delay occurs at the relay node
Solution Approach 1:
The patent applies preliminary action by performing RF transmission/reception switching before backhaul sub-frames begin. The relay node switches its RF mode in advance (before the backhaul sub-frame timing) so that when the backhaul transmission or reception occurs, the switching is already complete, eliminating switching delay during the critical backhaul operation.
Solution Approach 2:
The patent segments the sub-frame structure by designating specific symbols (first and/or last symbols) as blank symbols that are not used for data transmission. This segmentation creates dedicated time intervals for RF switching operations within the sub-frame structure, allowing the relay node to perform mode switching during these blank periods without interfering with data transmission.
2Productivity
If backhaul sub-frames are designed to minimize switching delay, then time efficiency improves, but compatibility with conventional sub-frame structures becomes difficult to maintain
Solution Approach 1:
The patent achieves universality by making the blank symbol configuration flexible and adaptable. The system can configure 1st, 2nd, or both symbols as blank symbols depending on whether uplink or downlink backhaul is performed, and adjust the number of blank symbols based on switching time requirements. This allows the same basic sub-frame structure to serve multiple functions (different backhaul directions and different switching time requirements) while maintaining compatibility with conventional LTE sub-frame structures.
Solution Approach 2:
The patent applies dynamics by making the blank symbol configuration changeable based on operational conditions. The relay node and base station can dynamically adjust which symbols are blank and how many blank symbols are used, depending on whether uplink or downlink backhaul is active and what switching time is required. This dynamic adaptation allows the system to optimize for time efficiency while maintaining structural compatibility.
3Loss of time
If predefined symbols are used as blanks in sub-frames, then RF switching time delay is reduced, but resource utilization decreases due to unused symbols
Solution Approach 1:
The patent applies partial action by using only the minimum necessary number of blank symbols required for RF switching. Instead of making entire sub-frames blank or using excessive blank symbols, the system configures only the specific symbols (1st, 2nd, or both) that are actually needed for switching operations. This minimizes the impact on resource utilization while still achieving the goal of reducing switching delay.
Data Source
AI summary
In a relay based wireless communication system, a method for transmitting an uplink backhaul sub-frame of a relay node includes obtaining scheduling information for an uplink backhaul sub-frame through a downlink backhaul control channel from a base station, and performing a rate matching and mapping of data by regarding at least one predefined symbol as a blank symbol. The predefined symbol is located at a front part or a rear part of the scheduled uplink backhaul sub-frame. The transmitting method further includes performing a multiplexing of the uplink backhaul sub-frame, and transmitting the multiplexed uplink backhaul sub-frame. This method can eliminate an overlap of transmission and reception timing in a relay node due to an RF transmission/reception switching time delay. Also, the method can make better use of wireless backhaul resources and minimize an influence on conventional systems by offering the compatibility with conventional uplink and downlink sub-frame structures.