Dynamic Radio Format Adjustment for Doppler Shift Compensation
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Solution Overview
Problem
The conventional LTE radio access scheme is inadequate for the 5G radio access system, particularly when high frequencies are used, leading to degraded communication capability due to Doppler shift and increased FFT size issues, and cannot meet requirements for low data latency and wide frequency bands.
Innovation Solution
A communication system where the base station sets a radio format for each communication terminal device based on its type of use, including moving speed, to accommodate various devices and improve spectral efficiency by adjusting OFDM subcarrier intervals and cyclic prefix lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LTE radio access scheme is used, then system compatibility is maintained, but communication capability degrades due to Doppler shift at high frequencies
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting OFDM subcarrier intervals based on terminal moving speeds. The base station sets different subcarrier intervals (e.g., first subcarrier interval for low speed, second subcarrier interval for high speed) to compensate for Doppler shift effects, thereby maintaining communication capability across varying frequency conditions
2Productivity
If fixed OFDM subcarrier interval is used, then system simplicity is maintained, but spectral efficiency decreases when accommodating terminals with different moving speeds
Solution Approach 1:
The patent implements dynamics by making the OFDM subcarrier interval adjustable rather than fixed. The base station dynamically selects between multiple subcarrier intervals based on terminal capabilities and moving speeds, enabling the system to adapt to different spectral efficiency requirements while managing device complexity through predefined configuration options
Solution Approach 2:
The patent applies local quality by configuring different radio formats with specific subcarrier intervals for different terminal types or moving speed ranges. This allows optimized spectral efficiency for each local condition (terminal type/speed category) while maintaining overall system coherence
3Area of stationary object
If large FFT size is used to support wide frequency bands, then frequency band coverage is improved, but implementation complexity and power consumption increase
Solution Approach 1:
The patent applies parameter changes by adjusting the relationship between subcarrier interval and FFT size. By varying the subcarrier interval based on terminal capabilities, the system can achieve wide frequency band coverage with smaller FFT sizes for specific terminal types, thereby reducing implementation complexity and power consumption while maintaining necessary frequency coverage
4Loss of time
If uniform radio format is used for all terminals, then system simplicity is maintained, but data latency increases due to inability to optimize for high-speed terminals
Solution Approach 1:
The patent implements dynamics by enabling the base station to dynamically select radio formats optimized for different terminal types and moving speeds. This allows low data latency for high-speed terminals through appropriate format selection while maintaining system simplicity through the use of predefined format configurations
Data Source
AI summary
A base station device is configured to set, for each communication terminal device, a radio format for signals transmitted to and received from the communication terminal device. The radio format is set for each communication terminal device in accordance with, for example, a type of use including a moving speed of the communication terminal device. The base station device may be configured to change the radio format for the communication terminal device based on the information about a change in the environment of a radio communication between the communication terminal device and the base station device and a change including the communication terminal device's location. The signals transmitted and received between the base station device and the communication terminal device include radio formats in which at least one of a length of a symbol of the signal and a length of a cyclic prefix in an OFDM scheme differs.