TDD Relay Characteristic Switching for Asymmetric Uplink and Downlink
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Solution Overview
Problem
Existing communication systems using relays for radio base stations and terminals face inefficiencies due to differences in the number and distribution of terminals between downlink and uplink communications, leading to suboptimal relay characteristics that do not adequately support both directions.
Innovation Solution
Implementing a time division duplex (TDD) scheme to separately determine and switch relay characteristics for downlink and uplink periods, allowing flexible adjustment of coverage areas to match the specific needs of each communication direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the relay characteristic is set to concentrate transmission paths on the radio terminal in downlink communication, then communication quality is improved, but the relay characteristic becomes inappropriate for uplink communication
Solution Approach 1:
The relay characteristic is made dynamic by switching between downlink relay characteristic and uplink relay characteristic according to the communication direction. The relay control section receives switching control signals from the base station and dynamically adjusts the relay characteristic to match the current communication direction, enabling the system to adapt to different transmission scenarios while maintaining optimal performance.
Solution Approach 2:
The relay characteristic parameters (such as beamforming weights, reflection coefficients, or signal routing) are changed based on the communication direction. The base station determines appropriate relay characteristics for each direction and transmits control signals to the relay, causing the relay to adjust its parameters to optimize performance for either downlink or uplink communication.
2Device complexity
If a single relay characteristic is used for both downlink and uplink communications, then device complexity is reduced, but communication performance is not sufficiently optimized
Solution Approach 1:
The relay communication is segmented into downlink and uplink phases with distinct relay characteristics. The base station transmits switching control signals that divide the communication timeline into segments, each optimized for its specific direction. This segmentation allows each phase to use tailored relay characteristics without requiring the relay to handle both directions simultaneously with a single configuration.
Solution Approach 2:
The relay characteristic switching operates periodically according to the TDD frame structure. The base station sends switching control signals at regular intervals corresponding to the transition between downlink and uplink periods. This periodic switching enables the relay to maintain optimal performance for each communication direction while following a predictable, manageable pattern that does not excessively increase control complexity.
3Length of moving object
If beamforming is used to compensate for radio wave attenuation, then transmission distance is increased, but the number of spatial multiplexing is limited to one or two
Solution Approach 1:
The relay acts as an intermediary that enables multiple spatial multiplexing while maintaining beamforming benefits. Instead of the base station directly performing beamforming to a single terminal, the relay receives beamformed signals and retransmits them to multiple terminals. This intermediary approach allows the system to achieve both extended transmission distance through beamforming and increased spatial multiplexing capacity through the relay's ability to serve multiple users.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances communication performance by ensuring appropriate transmission paths are formed for both downlink and uplink communications, improving quality and spatial multiplicity.
Implementation Method 1
The relay reflects a signal transmitted from the radio base station or the radio terminal, or receives and reradiates the signal
Data Source
AI summary
A radio base station and a radio terminal perform radio communication based on a TDD scheme. A slot configuration includes allocation of a downlink period and an uplink period to the radio terminal. The relay reflects a signal transmitted from the radio base station or the radio terminal or receives and reradiates the signal to form a transmission path between the radio base station and the radio terminal. A relay characteristic includes a parameter determining a coverage area in which the transmission path is formed. A downlink relay characteristic during the downlink period and an uplink relay characteristic during the uplink period are not common but determined separately. Then, the relay characteristic during the downlink period is set to the downlink relay characteristic, and the relay characteristic during the uplink period is set to the uplink relay characteristic. In other words, the relay characteristic is switched between downlink communication and uplink communication.