Reference Signal Cyclic Shift Randomization for Lower Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems like LTE and NR, reference signals from different terminal devices interfere with each other due to fixed cyclic shift values, leading to increased interference and reduced channel estimation accuracy, especially at cell edges.
Innovation Solution
Randomize the cyclic shift values of reference signals using pseudo-random sequences based on first and second parameters, ensuring that the cyclic shift values are determined differently for each terminal device, thereby reducing interference and improving channel time-domain filtering performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed cyclic shift values are used for reference signals, then orthogonality between reference signals from different terminal devices is ensured, but interference between reference signals from different base sequences cannot be eliminated
Solution Approach 1:
The patent applies dynamics by making the cyclic shift value variable rather than fixed. The cyclic shift value changes according to a pseudo-random sequence that depends on time parameters (slot number, symbol number) and device-specific parameters (device identifier, base sequence identifier). This dynamic adjustment allows the system to maintain orthogonality while reducing interference through randomized phase differences between reference signals from different base sequences.
Solution Approach 2:
The patent changes the parameter of cyclic shift value from a static allocation to a dynamic parameter that varies with time and device characteristics. By introducing pseudo-random sequences based on slot numbers, symbol numbers, and device identifiers, the cyclic shift parameter becomes a function of multiple variables, thereby transforming fixed orthogonality into adaptive orthogonality that also provides interference randomization.
2Measurement precision
If different cyclic shift values are allocated to different terminal devices, then orthogonality is maintained within a cell, but interference between reference signals from different base sequences remains non-zero
Solution Approach 1:
The patent converts the harmful fixed cyclic shift pattern into a beneficial randomized pattern. By using pseudo-random sequences, the previously harmful deterministic interference between different base sequences is transformed into random interference that can be averaged out through time-domain filtering, thereby converting a detrimental fixed pattern into a beneficial randomization mechanism.
Solution Approach 2:
The patent implements periodic action through the use of time-varying pseudo-random sequences that change with slot numbers and symbol numbers. This periodic variation in cyclic shift values ensures that interference patterns change over time, allowing the receiver to perform time-domain filtering to average out the interference and improve channel estimation accuracy.
3Measurement precision
If randomization of cyclic shift values is implemented, then interference is reduced and channel estimation accuracy is improved, but system complexity increases due to pseudo-random sequence generation
Solution Approach 1:
The patent applies self-service by enabling terminal devices to autonomously generate their own cyclic shift values using pseudo-random sequences based on their own device identifiers and the current time parameters. Each device independently computes its cyclic shift without requiring complex network coordination or additional signaling, thereby reducing system-level complexity while achieving interference randomization.
Data Source
AI summary
A signal sending method, a signal detection method, and an apparatus are disclosed. In the signal sending, a sequence of a reference signal is generated first, where the cyclic shift value of the sequence is determined based on a first parameter and a second parameter, the first parameter is a value from 0 to Q−1, the second parameter is a value from 0 to Z−1, Z and Q are positive integers, and Z is not equal to Q. The reference signal is then sent based on the sequence. According to the method, a difference between the cyclic shift values used by any two terminal devices to determine the sequences of reference signals can be randomized. Further, interference between reference signals generated by using the cyclic shift values obtained by terminal devices according to the method disclosed here can be reduced, the interference can be randomized, and the channel time-domain filtering performance can be improved.