Cyclic Shift Control for Demodulation Reference Symbols
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Solution Overview
Problem
In cellular communication networks, misinterpretation of ACK as NACK by wireless devices can lead to uplink conflicts and failed transmissions due to resource allocation errors, which are not resolved until the maximum number of retransmissions is reached.
Innovation Solution
A method and network node that dynamically control cyclic shift parameters for demodulation reference symbols based on the subframe index, ensuring that retransmissions have a different cyclic shift than the original transmission, allowing the network node to differentiate and suppress interfering signals, thereby reducing conflicts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same cyclic shift parameter is used for original transmission and retransmission, then the wireless device maintains consistent signal characteristics, but uplink conflicts occur when ACK is misinterpreted as NACK causing resource allocation errors
Solution Approach 1:
The patent applies dynamics by making the cyclic shift parameter time-varying through its dependency on the subframe index. The network node determines a first cyclic shift parameter based on the current subframe index, and this parameter changes over time. This dynamic approach ensures that retransmissions have a different cyclic shift than the original transmission, allowing the network node to differentiate and suppress interfering signals, thereby resolving uplink conflicts while maintaining transmission reliability.
Solution Approach 2:
The patent changes the cyclic shift parameter dynamically based on the subframe index. By determining the first cyclic shift parameter based on the current subframe index, the system modifies the parameter value over time. This parameter change ensures that when ACK is misinterpreted as NACK, the retransmission uses a different cyclic shift than the original transmission, preventing resource allocation conflicts and allowing the network node to correctly decode signals from multiple wireless devices.
2Object-affected harmful factors
If dynamic cyclic shift control based on subframe index is implemented, then uplink conflicts are reduced, but the system complexity increases due to additional parameter determination and control message generation
Solution Approach 1:
The patent implements dynamic cyclic shift control by determining the first cyclic shift parameter based on the current subframe index. This parameter change approach reduces uplink conflicts while the complexity is managed by integrating the determination process into the existing network node operations. The network node generates control messages containing the first cyclic shift parameter and transmits them to wireless devices, implementing the dynamic control in a systematic manner that balances conflict reduction with operational complexity.
Data Source
AI summary
It is presented a method for controlling cyclic shift for demodulation reference symbols for uplink communication in a cellular communication network. The method is performed in a network node and comprises the steps of: determining a first cyclic shift parameter for demodulation reference symbols based on a current subframe index; generating a control message comprising the first cyclic shift parameter; and transmitting the control message to a wireless device of the cellular communication network. Corresponding network nodes, computer program and computer program product are also presented.