Rotating FDD Transceiver for Massive MIMO CSI Overhead
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Solution Overview
Problem
Massive MIMO technology is not compatible with frequency division duplexing (FDD) systems due to high channel state information (CSI) overhead, and current FDD systems lack capacity adaptation between uplink and downlink, which is essential for next-generation wireless communication systems with asymmetric traffic dynamics.
Innovation Solution
The implementation of rotating frequency division duplexing (RFDD), synchronous dual band time division duplexing (STDD), and asynchronous dual band time division duplexing (ATDD) architectures, which allow for adaptive resource allocation and CSI acquisition between uplink and downlink in non-contiguous bands, reducing CSI overhead and enabling capacity adaptation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If frequency division duplexing (FDD) systems are used, then uplink and downlink can operate simultaneously, but channel state information (CSI) overhead increases significantly
Solution Approach 1:
The system dynamically switches between FDD and TDD modes based on traffic conditions and channel characteristics. By making the duplexing mode flexible rather than fixed, the system can adapt to varying requirements: using FDD when simultaneous operation is needed and TDD when CSI overhead can be reduced through uplink-downlink channel reciprocity.
Solution Approach 2:
The patent changes the operational parameters by allowing the system to transition between different duplexing configurations (FDD/TDD) and different band allocations (contiguous/non-contiguous). This parameter flexibility enables optimization of CSI overhead while maintaining simultaneous uplink-downlink capability when required.
2Productivity
If traditional FDD systems are used, then frequency resources are fixed, but capacity adaptation between uplink and downlink is lacking
Solution Approach 1:
The system implements dynamic capacity adaptation by allowing flexible adjustment of uplink and downlink resource allocation. The base station can dynamically determine the number of uplink and downlink subframes within a frame structure, enabling the system to adapt capacity distribution according to real-time traffic demands while maintaining fixed frequency operation when using FDD mode.
Solution Approach 2:
The patent creates a universal system that can function in multiple modes: FDD mode for simultaneous operation, TDD mode for adaptive capacity allocation, supporting both contiguous and non-contiguous band configurations. This multi-functionality allows the same system architecture to serve diverse capacity adaptation requirements.
3Productivity
If massive MIMO is implemented in FDD systems, then data rates increase, but CSI overhead becomes prohibitively high
Solution Approach 1:
The system dynamically selects between FDD and TDD operational modes to optimize the trade-off between data rate and CSI overhead. When TDD mode is selected for massive MIMO operation, the system exploits channel reciprocity to reduce CSI overhead significantly, while still achieving high data rates through multi-antenna technology.
Solution Approach 2:
The patent changes the operational parameters by enabling flexible mode selection (FDD/TDD) and configurable band structures (contiguous/non-contiguous). This allows the system to optimize for low CSI overhead by selecting TDD mode with appropriate subframe configurations when deploying massive MIMO, while maintaining the capability for high data rates.
4Productivity
If uplink and downlink use different frequency bands, then simultaneous transmission is enabled, but resource allocation flexibility is reduced
Solution Approach 1:
The system dynamically adjusts resource allocation within the frame structure by flexibly configuring the number and positions of uplink and downlink subframes. This dynamic subframe configuration allows the system to maintain simultaneous transmission capability while achieving fine-grained resource allocation flexibility to match varying traffic patterns.
Solution Approach 2:
The patent segments the frame structure into multiple configurable subframes that can be independently assigned as uplink or downlink. This segmentation enables flexible resource allocation by allowing different proportions of uplink and downlink resources across different time periods within the same frame structure, while preserving simultaneous transmission capability when using FDD mode.
Data Source
AI summary
A multi-input multi-output rotating frequency division duplexing transceiver in non-contiguous bands comprising an adaptive duplex filter, a controller coupled to the adaptive duplex filter, wherein an uplink band and a downlink band are rotated before each transmission sub-frame, and wherein at least two of the bands are non-contiguous, a multi-output adaptive frequency synthesizer coupled to the controller, a transmit mixer coupled to the adaptive duplex filter and to the multi-output adaptive frequency synthesizer and a receive mixer coupled to the adaptive duplex filter and to the multi-output adaptive frequency synthesizer.