FDD-TDD Resource Allocation for Interference Reduction
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Solution Overview
Problem
Current radio communication systems face challenges in efficiently allocating resources to frequency bands, particularly in preventing interference between base stations using Time Division Duplex (TDD) while maintaining flexibility and accommodating asymmetrical traffic conditions.
Innovation Solution
A method that allocates resources in two FDD frequency bands, where one band is primarily used for downlink TDD and uplink FDD, and the other for uplink TDD and downlink FDD, with synchronized allocation of resources to minimize interference and adapt to traffic loads, allowing for both symmetrical and asymmetrical traffic support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TDD is used for short-range transmissions, then channel estimation accuracy is improved through reciprocity, but interference between base stations deteriorates due to uncoordinated uplink/downlink switching
Solution Approach 1:
The system divides the frequency spectrum into separate FDD bands for uplink and downlink, while within each band segments time into TDD slots. This segmentation allows uplink FDD transmissions to occur in dedicated frequency bands during specific time periods, preventing them from interfering with downlink TDD transmissions in other bands, thus resolving the interference problem while maintaining channel estimation accuracy
Solution Approach 2:
The patent implements a nested structure where TDD time-slot segmentation is embedded within FDD frequency band allocation. The outer layer uses FDD to separate uplink and downlink in frequency, while the inner layer uses TDD to further segment time slots for additional flexibility. This nested approach allows simultaneous FDD and TDD operations without mutual interference
2Object-affected harmful factors
If FDD is used for long-range transmissions, then interference conditions are improved with clearly defined separation, but flexibility to accommodate asymmetrical traffic deteriorates due to fixed frequency allocation
Solution Approach 1:
The system dynamically allocates time slots within FDD bands based on traffic demands. The network device can adjust the number and duration of uplink FDD time periods and downlink TDD time periods in response to changing traffic conditions, allowing the system to adapt to asymmetrical traffic while maintaining the interference benefits of FDD separation
Solution Approach 2:
Each FDD band is designed to serve multiple functions: it can operate as an uplink FDD band during designated time periods and as a downlink TDD band during other periods. This multi-functionality allows the same frequency resources to accommodate both FDD and TDD transmission modes, providing flexibility for asymmetrical traffic while maintaining clear interference boundaries
3Adaptability or versatility
If resources are allocated for secondary transmission direction in TDD, then system flexibility is improved, but capacity loss occurs due to no resources allocated for counter transmission direction
Solution Approach 1:
The system implements periodic alternation between uplink FDD time periods and downlink TDD time periods. During uplink FDD periods, resources are allocated for uplink transmissions, and during downlink TDD periods, resources are allocated for downlink transmissions. This periodic switching allows the system to flexibly adapt to traffic demands in each direction while minimizing capacity loss by ensuring that resources are continuously utilized in the dominant transmission direction
Data Source
AI summary
Resources of two frequency division duplex (FDD) frequency bands at a distance from each other are allocated for transmissions by a time division duplex (TDD) transmission method. The resources in the first FDD frequency band are allocated for FDD transmissions in the uplink and for TDD transmissions predominantly in the uplink as the primary transmission direction, and in a secondary manner in the downlink as the secondary transmission direction. The resources in the second FDD frequency band are allocated for FDD transmissions in the downlink and for TDD transmissions predominantly in the downlink as the primary transmission direction and in a secondary manner in the uplink as the secondary transmission direction. No resources are allocated for time periods of an allocation of resources for one of the secondary transmission directions in the first and second frequency bands, for FDD transmissions in the counter transmission direction to this secondary transmission direction.