Uplink Waveform Selection via Downlink Characteristics
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Solution Overview
Problem
In wireless communication networks, especially in half-duplex systems like mmWave, there is uncertainty about the waveform type used by user equipment (UE) during RRC reconfiguration, leading to inefficiencies and complexities in uplink transmissions due to the need for negotiation between different waveform types such as OFDM and DFTS-OFDM.
Innovation Solution
The UE selects the uplink waveform based on characteristics of the downlink transmission, such as the search space, control resource sets, modulation and coding schemes, or RNTI, to align with the network's expectations, thereby reducing uncertainty and improving transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If waveform negotiation is performed between UE and network during RRC reconfiguration, then waveform compatibility is ensured, but transmission efficiency decreases due to uncertainty period and additional signaling overhead
Solution Approach 1:
The network pre-configures multiple waveform types (e.g., CP-OFDM, DFTS-OFDM) and their associated parameters in the RRC reconfiguration message before the actual uplink transmission. This allows the UE to have waveform information ready in advance, eliminating the need for real-time negotiation and reducing the uncertainty period.
Solution Approach 2:
The patent introduces waveform indication parameters (such as waveformType, subcarrierSpacing, cyclicPrefixLength) that can be dynamically changed and signaled from network to UE. By changing these parameters through preconfiguration rather than negotiation, the system maintains reliability while improving transmission efficiency.
2Adaptability or versatility
If multiple waveform types are supported for uplink transmission, then system flexibility and adaptability improve, but device complexity increases due to need to handle multiple waveform configurations
Solution Approach 1:
The network side is designed to universally support multiple waveform types (CP-OFDM, DFTS-OFDM, and future waveforms) and configure them through a unified RRC signaling mechanism. This multi-functionality at the network side simplifies the UE implementation, as the UE only needs to follow the configured waveform instructions without implementing multiple waveform generation and selection mechanisms.
Solution Approach 2:
The complex waveform configuration and management functionality is extracted from the UE and relocated to the network side. The network handles waveform selection, parameter configuration, and updates, while the UE simply executes the configured waveform. This extraction reduces device complexity while maintaining system flexibility.
3Productivity
If waveform information is signaled dynamically in each uplink grant, then transmission efficiency improves, but signaling overhead increases
Solution Approach 1:
Waveform information is preliminarily signaled in the RRC reconfiguration message rather than being dynamically included in each uplink grant. This pre-signaling approach reduces the signaling overhead in individual uplink grants while maintaining transmission efficiency, as the UE already has the waveform configuration ready before the uplink transmission occurs.
Data Source
AI summary
Methods and related radio network nodes and user equipment are described for the indication of waveform in wireless communication networks. The methods include, and related radio network nodes and user equipment adapted to, receiving a downlink transmission from a radio network node, where the downlink transmission having at least one characteristic; selecting one waveform from two or more waveforms for an upcoming uplink transmission to the radio network node, where the waveform being selected based at least in part on the at least one characteristic of the downlink transmission; and transmitting the uplink transmission to the radio network node using the selected waveform.