Uplink Channel Estimation Using Orthogonal Sequences
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Solution Overview
Problem
Current channel estimation methods for large numbers of UEs in IoT scenarios are inefficient due to sequential channel estimation and high interference among UEs, leading to increased time and computational complexity, especially in scenarios where multiple UEs need to perform channel estimations simultaneously.
Innovation Solution
A method for uplink channel estimation in a base station that determines whether multipath signals from UEs pass through the same beam sector, assigns orthogonal training sequences to UEs, and performs channel estimation using Zadoff-Chu sequences to mitigate multi-UE interference, allowing simultaneous channel estimation across multiple UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If UEs perform channel estimations sequentially using traditional methods, then interference among UEs is reduced, but the time required for channel estimation increases significantly when many UEs are served simultaneously
Solution Approach 1:
The patent enables multiple UEs to perform channel estimations simultaneously through parallel processing at the base station. The receiver processes reference signals from multiple UEs in parallel using matrix operations, eliminating the need for sequential estimation and significantly reducing the total time required while maintaining estimation accuracy through orthogonal training sequences that prevent mutual interference.
Solution Approach 2:
The patent segments the channel estimation process by assigning different orthogonal training sequences to different UEs. This segmentation allows the base station to separate and process each UE's channel estimation independently through correlation operations, enabling simultaneous estimation without interference while maintaining the precision of individual estimations.
2Loss of time
If UEs perform channel estimations simultaneously by transmitting training sequences, then channel estimation time is reduced, but interference among training sequences from multiple UEs increases
Solution Approach 1:
The patent applies local quality by assigning different orthogonal training sequences to different UEs based on their specific channel conditions and beam sectors. This localized differentiation ensures that each UE's training sequence is optimized for its specific context, allowing simultaneous transmission without mutual interference while maintaining estimation accuracy.
Solution Approach 2:
The patent converts the potentially harmful effect of multiple simultaneous training sequences into a benefit by using orthogonal sequences. The orthogonality property transforms what would be interfering signals into separable signals, allowing the base station to extract each UE's channel information independently through correlation operations, thus turning simultaneous transmission from a source of interference into a means of parallel processing.
3Device complexity
If TRDMA is used for broadband communication, then computational complexity at the receiver is reduced, but channel estimation errors cause mismatch between time-reversal and corresponding channel
Solution Approach 1:
The patent applies preliminary action by performing accurate channel estimation during the training phase using orthogonal sequences before actual data transmission. This preliminary estimation establishes reliable channel state information that is then used for time-reversal operations, ensuring that the TRDMA processing is based on accurate channel knowledge and minimizing mismatch errors.
Solution Approach 2:
The patent incorporates feedback mechanisms where the base station uses the estimated channel information to adjust and refine the time-reversal processing. The channel estimation results feed back into the TRDMA system to optimize the signature waveforms, ensuring that the simplified receiver structure maintains high reliability through continuous adaptation based on actual channel conditions.
Data Source
AI summary
A method of performing uplink channel estimation and a base station using the same are provided. The method is applicable to serve at least two UE equipments (UEs) in a communication system. The at least two UEs are located in at least two beam sectors respectively. The base station comprises a plurality of antennas. The method includes: determining whether multipath of the at least two UEs passing through a same beam sector; assigning a first and a second training sequence for a first UE and a second UE of the at least two UEs respectively; receiving a reference signal, wherein the reference signal is transmitted by the first UE and the second UE according to the first and the second training sequence; and performing channel estimation for the first UE and the second UE according to the reference signal, the first and the second training sequence.