Uplink Control Channel Cyclic Shift Assignment for User Separation
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Solution Overview
Problem
Future radio communication systems face challenges in maintaining the quality of uplink control channels due to interference between user terminals, particularly when using cyclic shift for code-multiplexing.
Innovation Solution
A user terminal determines cyclic shifts for uplink control channels based on orthogonal cover codes and time resources, ensuring distinct cyclic shifts are used among multiple user terminals to minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cyclic shift is used for code-multiplexing uplink control channels, then the capacity for multiple user terminals is improved, but interference between user terminals increases and channel quality degrades
Solution Approach 1:
The patent applies different cyclic shift values to different user terminals based on their specific channel conditions and resource allocations. By customizing the cyclic shift parameter for each terminal rather than using a uniform approach, the system achieves better separation between multiplexed users while minimizing inter-terminal interference, thus resolving the contradiction between multiplexing capacity and interference levels
Solution Approach 2:
The patent dynamically adjusts cyclic shift parameters based on channel state information, resource block allocations, and user terminal characteristics. By changing the cyclic shift parameter values adaptively rather than using fixed values, the system optimizes the balance between supporting multiple users and maintaining signal quality, effectively managing the trade-off between productivity and harmful interference
2Adaptability or versatility
If cyclic shift is applied to demodulation reference signals, then code-multiplexing capability is enhanced, but uplink control channel quality may be degraded due to interference
Solution Approach 1:
The patent pre-calculates and assigns appropriate cyclic shift values to demodulation reference signals before actual transmission, based on predicted channel conditions and user terminal configurations. This preliminary assignment ensures that reference signals from different users are sufficiently separated in the cyclic shift domain, preventing interference before it occurs and maintaining both multiplexing capability and channel quality
Solution Approach 2:
The patent introduces carefully selected cyclic shift values as intermediary parameters that mediate between the need for code-multiplexing and the requirement for signal quality. By using cyclic shift as a controllable intermediary variable, the system can achieve user separation while maintaining reference signal integrity, thus resolving the contradiction between adaptability and reliability
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3A~3B
AI summary
The present invention is designed to improve the performance of uplink control channels that are code-multiplexed among a plurality of user terminals. A user terminal has a transmission section that transmits an uplink control channel, containing data, to which an orthogonal cover code is applied before discrete Fourier transform, and a demodulation reference signal, to which a cyclic shift is applied, and a control section that executes control so that the cyclic shift is determined based on an index of the orthogonal cover code, a time resource of the demodulation reference signal and a length of the orthogonal cover code or a maximum value of the length.