Uplink Scheduling Adaptation for FDD Resource Utilization
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Solution Overview
Problem
In LTE FDD systems, the use of Almost Blank Subframes (ABS) and half-duplex operation leads to significant loss of uplink transmission capacity due to subframe blanking, limiting flexibility and increasing energy consumption, as uplink grants cannot be transmitted during blanked subframes, resulting in 25% of uplink capacity being unschedulable.
Innovation Solution
Implementing a Time Division Duplex (TDD) configuration in the scheduling of resources, where the network node determines if a UE is prohibited from receiving an uplink grant and sends an indication to apply a TDD configuration, allowing uplink transmissions in previously unschedulable subframes by adjusting the timing of scheduling and HARQ protocol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If Almost Blank Subframes (ABS) are used to mitigate interference, then downlink interference is reduced, but uplink transmission capacity is significantly lost
Solution Approach 1:
The patent applies dynamics by making the uplink transmission timing flexible and adaptable. Instead of fixed FDD timing, the system dynamically adjusts uplink transmission timing based on downlink subframe availability, allowing the timing relationship to change according to traffic conditions and ABS patterns, thereby resolving the contradiction between interference mitigation and capacity utilization
Solution Approach 2:
The patent changes the timing parameter from fixed (N+4 in FDD) to variable, allowing different timing offsets based on subframe conditions. This parameter change enables the system to adapt to ABS patterns while maintaining uplink transmission capability, converting the rigid timing constraint into a flexible parameter that can be optimized for both interference reduction and capacity utilization
2Object-affected harmful factors
If subframe blanking is applied to reduce interference, then interference coordination is improved, but scheduling flexibility is limited
Solution Approach 1:
The patent introduces dynamic scheduling flexibility by allowing the network to adaptively determine uplink transmission timing based on downlink subframe conditions. The system can dynamically adjust timing relationships and select different uplink subframes for transmission, providing scheduling flexibility that adapts to both ABS patterns and varying traffic requirements, thus resolving the contradiction between interference coordination and scheduling adaptability
3Device complexity
If uplink grants are not transmitted during blanked subframes, then resource allocation is simplified, but uplink capacity utilization decreases
Solution Approach 1:
The patent applies preliminary action by having the network proactively determine the set of available uplink subframes based on downlink subframe conditions before actual uplink transmission occurs. The network pre-calculates which uplink subframes can be used and provides this information to the UE in advance, allowing the UE to prepare and transmit without waiting for dynamic grants during blanked subframes, thereby improving capacity utilization while maintaining manageable complexity
Solution Approach 2:
The patent enables self-service by allowing the UE to autonomously select uplink subframes for transmission based on pre-configured timing relationships and available downlink subframes. The UE can independently determine when to transmit uplink data without requiring explicit grants for each transmission opportunity, reducing the need for complex grant management while maximizing uplink capacity utilization through autonomous resource selection
Data Source
AI summary
A user equipment, a network node and methods thereof for timing of scheduling of resources in a frequency division duplex system are disclosed. The user equipment and network node operate in a frequency division duplex communication system. The network node determines (400) whether a user equipment is prohibited to receive an uplink grant in at least one downlink subframe, e.g. if the user equipment is configured with ABS or with half-duplex operation. Furthermore, if the user equipment is prohibited to receive an uplink grant in at least one downlink subframe, the network node sends (410) an indication to the user equipment to apply a time division duplex configuration to the timing of scheduling of resources. The user equipment receives (420) the indication and thereupon applies (430) the time division duplex configuration to the timing of scheduling of resources.