Uplink Reference Signal Sequence Selection for Interference Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, interference occurs when uplink signals and demodulation reference signals from multiple terminals have the same characteristics, leading to reduced accuracy in channel state estimation and demodulation.
Innovation Solution
A terminal device varies the base sequence number of its uplink demodulation reference signal to reduce interference, using cyclic shifts and sequence hopping to orthogonalize the reference signals, thereby minimizing interference with other terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple terminals transmit uplink signals and demodulation reference signals with the same characteristics, then the system can maintain simplicity in signal design and implementation, but interference occurs between terminals leading to reduced accuracy in channel state estimation and demodulation
Solution Approach 1:
The patent applies parameter changes by varying the base sequence number of demodulation reference signals based on terminal identification information. This changes the signal characteristics parameter (base sequence number) to differentiate between terminals, thereby reducing interference while maintaining relatively simple signal design. The base sequence number is selected from multiple candidate sequences according to terminal ID, achieving orthogonality or near-orthogonality between terminals.
2Measurement precision
If the base sequence number of demodulation reference signals is varied to reduce interference, then channel state estimation accuracy improves, but the complexity of signal generation and management increases
Solution Approach 1:
The patent manages the complexity of varying base sequence numbers by establishing a deterministic mapping between terminal identification information and candidate base sequence numbers. This mapping rule allows terminals to autonomously select appropriate base sequence numbers without complex coordination, improving channel state estimation accuracy while keeping signal generation manageable through predefined selection criteria.
Solution Approach 2:
Each terminal autonomously determines its base sequence number based on its own identification information and the predefined mapping rules. This self-service mechanism eliminates the need for centralized assignment or complex inter-terminal coordination, reducing signaling overhead and management complexity while achieving interference reduction through differentiated base sequence numbers.
3Object-affected harmful factors
If orthogonal sequences are used to mitigate interference between demodulation reference signals, then interference reduction is achieved, but the available sequence resources are limited and system adaptability decreases
Solution Approach 1:
The patent extends the interference mitigation capability beyond strict orthogonal sequences by utilizing multiple candidate base sequences with varying degrees of correlation. This allows the system to adapt to different terminal combinations and channel conditions by selecting from a larger pool of sequences, reducing interference while maintaining system adaptability. The mapping from terminal ID to candidate sequences provides flexibility in sequence selection.
Solution Approach 2:
The system dynamically selects base sequence numbers based on terminal identification information and channel conditions. Rather than assigning fixed orthogonal sequences, the patent enables dynamic adaptation of sequence selection, allowing the system to respond to changing traffic patterns and interference conditions, thereby maintaining both interference reduction and system versatility.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
There are provided a terminal device, a base station device, and an integrated circuit that enable a base station device and a terminal device to determine parameters related to uplink signals or uplink reference signals and to perform efficient communication. A terminal device that transmits a demodulation reference signal associated with a physical uplink shared channel to a base station device includes determining a base sequence number on the basis of a value of a parameter configured by a higher layer, determining the base sequence number on the basis of a physical layer cell identity, and generating a sequence of the demodulation reference signal on the basis of the base sequence number, wherein the base sequence number is determined on the basis of the physical layer cell identity in a case where a transmission on the physical uplink shared channel corresponding to a downlink control information format to which CRC parity bits scrambled by a Temporary C-RNTI are attached is performed in a random access procedure.