MU-MIMO Pilot Signal Spatial Orthogonality
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Solution Overview
Problem
In MU MIMO systems, the number of orthogonal pilots increases with paired data streams, leading to increased overhead and reduced system gain due to higher interference, which affects spectral efficiency and capacity.
Innovation Solution
The use of precoding technology to make pilot signals spatially orthogonal, ensuring that the number of pilots remains fixed regardless of the number of paired data streams, by determining transmitting precoding vectors for primary and secondary pilot signals based on spatial channel information, allowing them to be orthogonal to each other.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of orthogonal pilots is increased to support more paired data streams in MU MIMO system, then the system capacity and spectral efficiency are improved, but the pilot overhead occupies more transmission resources and reduces the useful data transmission capacity
Solution Approach 1:
The patent transitions from traditional code-division or frequency-division orthogonal pilot designs to spatial-division orthogonal pilot design. By utilizing the spatial dimension through precoding technology, the system achieves pilot orthogonality across different spatial channels, allowing multiple users to share the same time-frequency resources with reduced pilot overhead while supporting increased data streams.
Solution Approach 2:
The patent changes the orthogonality parameter from code domain or frequency domain to spatial domain. By determining transmitting precoding vectors based on spatial channel information and making pilot signals spatially orthogonal, the system reduces pilot overhead while maintaining the ability to support multiple paired data streams in MU MIMO transmission.
2Adaptability or versatility
If more orthogonal pilots are used to support increased paired data streams, then more users can be served concurrently, but the interference between multiple streams increases and reduces system gain
Solution Approach 1:
The patent applies different precoding vectors to different spatial channels, creating locally optimized pilot signals for each user's specific channel conditions. This spatial differentiation allows the system to serve multiple users concurrently while minimizing inter-user interference through channel-specific precoding tailored to each receiver's spatial characteristics.
Solution Approach 2:
The patent changes the orthogonality parameter from code domain or frequency domain to spatial domain. By determining transmitting precoding vectors based on spatial channel information and making pilot signals spatially orthogonal, the system reduces pilot overhead while maintaining the ability to support multiple paired data streams in MU MIMO transmission.
3Measurement precision
If traditional code division or code division and frequency division orthogonal pilots are used, then the receiver can obtain clean channel information, but the pilot overhead is high and occupies 14.3% of all transmission resources
Solution Approach 1:
The patent transitions from traditional code-division or frequency-division orthogonal pilot designs to spatial-division orthogonal pilot design. By utilizing the spatial dimension through precoding technology, the system achieves pilot orthogonality across different spatial channels, allowing multiple users to share the same time-frequency resources with reduced pilot overhead while maintaining clean channel information estimation.
Solution Approach 2:
The patent makes pilot signals spatially orthogonal through precoding, allowing the same time-frequency resources to be shared by multiple users simultaneously. This multi-functional approach enables the pilot signals to serve both channel estimation and spatial multiplexing purposes, reducing overall overhead while maintaining measurement precision.
Data Source
AI summary
Embodiments of the present invention provide a method and apparatus for sending and receiving a signal, and relate to the field of wireless communication, where a quantity of pilots does not increase with increasing paired data streams of an MU-MIMO system, and overheads of the pilots are fixed. The method includes: determining, by a transmitter, a transmitting precoding vector of a primary pilot signal of a first receiver and an estimated receiving filtering vector; determining a transmitting precoding vector of a secondary pilot signal of the first receiver; determining a to-be-sent primary pilot signal, to-be-sent user data of the first receiver, and a to-be-sent secondary pilot signal; and sending the first receiver the to-be-sent primary pilot signal, the to-be-sent user data of the first receiver, and the to-be-sent secondary pilot signal.