Signal Transmission Filtering in MIMO F-OFDM Systems
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Solution Overview
Problem
In filtered-orthogonal frequency division multiplexing (F-OFDM) systems, particularly in MIMO technology, the high complexity of filtering operations across multiple antenna ports leads to increased implementation complexity and costs, especially in uplink transmission scenarios.
Innovation Solution
The proposed method involves filtering time domain OFDM signals at each spatial transmission layer with a higher-order digital shaping filter, followed by spatial precoding and mapping to transmit antenna ports, where the number of filtering operations is proportional to the number of spatial transmission layers rather than transmit antenna ports, thereby reducing filtering complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If filtering operations are performed on time domain signals at each transmit antenna port in MIMO F-OFDM systems, then out-of-band performance is improved, but filtering complexity increases significantly
Solution Approach 1:
The patent segments the filtering operation from the antenna port processing. Instead of filtering at each antenna port independently, the system performs filtering on the time domain signal at each spatial transmission layer once, then applies spatial precoding to distribute the filtered signal across multiple antenna ports. This segmentation reduces the total number of filtering operations from Nt (number of antenna ports) to M (number of spatial layers), where M ≤ Nt.
Solution Approach 2:
The patent applies filtering as a preliminary action before spatial precoding. By filtering the time domain signal at each spatial transmission layer before the spatial distribution stage, the system ensures that all antenna ports receive already-filtered signals, eliminating the need for redundant filtering operations at each antenna port while maintaining the required out-of-band performance.
2Object-affected harmful factors
If higher-order digital shaping filters are used for filtering, then out-of-band performance is improved, but implementation complexity increases
Solution Approach 1:
The patent segments the filtering operation to be performed only M times (once per spatial layer) rather than Nt times (once per antenna port). This reduces the total computational burden of higher-order filtering operations, making implementation more feasible while still achieving the required out-of-band performance through the use of higher-order digital shaping filters on the reduced set of signals.
Data Source
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AI summary
Embodiments of this application provide a signal transmission method and apparatus, and the method includes: filtering a first time domain OFDM signal at each of M spatial transmission layers, where M is an integer greater than or equal to 1; performing spatial precoding on the filtered first time domain OFDM signal at each of the M spatial transmission layers, and mapping the filtered first time domain OFDM signal at each of the M spatial transmission layers to each of Nt transmit antenna ports, where Nt is an integer greater than or equal to M; and superposing and transmitting the first time domain OFDM signals that are at the M spatial transmission layers and that are mapped to all the Nt transmit antenna ports. By adjusting a sequence of performing spatial precoding and filtering, a quantity of filtering operations may be directly proportional to a quantity of spatial transmission layers, so that filtering complexity during signal transmission can be reduced.