Radio Propagation Channel Estimation via Null Space Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High Peak to Average Power Ratio (PAPR) in OFDM transmissions leads to in-band and out-of-band distortion, deteriorating system performance and making it difficult to meet stringent Error Vector Magnitude (EVM) requirements, especially for high modulation schemes.
Innovation Solution
Accurate estimation of the radio propagation channel's null space using uplink reference signals and Demodulation Reference Signals (DMRS) to reduce PAPR while maintaining EVM requirements, by configuring single port transmission and determining channel and null space estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM transmission is used to increase data rate, then throughput is improved, but PAPR increases causing in-band and out-of-band distortion
Solution Approach 1:
The patent segments the channel frequency response into multiple sections and performs separate null space estimation for each section. This allows the system to handle the high PAPR distortion effects in different frequency segments independently, reducing overall distortion while maintaining high throughput OFDM transmission
Solution Approach 2:
The patent performs preliminary null space estimation using uplink reference signals before actual data transmission. By pre-characterizing the channel nulls and distortion patterns, the system can compensate for PAPR-induced distortion in advance, ensuring both high throughput and low distortion during data transmission
2Object-generated harmful factors
If PAPR is reduced to minimize distortion, then in-band and out-of-band distortion is reduced, but transmission efficiency decreases
Solution Approach 1:
The patent uses null space estimation as an intermediary mechanism to decouple the relationship between PAPR reduction and distortion minimization. By identifying and exploiting channel nulls, the system can reduce distortion through targeted power allocation without requiring aggressive PAPR reduction that would harm transmission efficiency
Solution Approach 2:
The patent changes the power allocation parameters across different frequency subcarriers based on null space estimation results. By adjusting power distribution to match channel conditions, the system achieves low distortion in critical frequency regions while maintaining overall transmission efficiency
3Measurement precision
If single port transmission is configured for null space estimation, then null space estimation accuracy is improved, but transmission flexibility is reduced
Solution Approach 1:
The patent implements dynamic port configuration where the transmission port is selected based on real-time channel conditions and estimation requirements. Single port transmission is used when null space estimation accuracy is prioritized, while multi-port transmission can be activated when transmission flexibility is needed, allowing the system to adapt to different operational scenarios
Data Source
AI summary
There is provided mechanisms for estimating a radio propagation channel. A method is performed by a network node. The network node serving a user equipment over the radio propagation channel. The method comprises configuring (S104) the user equipment to use single port transmission for transmitting on an uplink data channel to the network node. The method comprises transmitting (S106) downlink control information towards the user equipment. The downlink control information indicates which port the user equipment is to use for transmission of DMRS on the uplink data channel. The method comprises receiving (S108) uplink reference signals from the user equipment and uplink data and the DMRS on the uplink data channel from the user equipment. The method comprises determining (Slid) a channel estimate of the radio propagation channel, and a null space estimate of the radio propagation channel, from the received uplink reference signals and the received DMRS.