Superimposing Data and Reference Signals in MIMO Systems
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Solution Overview
Problem
In multiuser beamforming systems, the intensities of reference signals received by users are relatively small, leading to underutilization of orthogonal resources, as these signals occupy main layer resources without being fully utilized.
Innovation Solution
A method and apparatus for superimposing data signals and reference signals in a space division multiple access communication system, where the same time/frequency resources are used for both layers, with data signals being transmitted at positions of reference signals and employing orthogonal spreading sequences to ensure efficient resource utilization and minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reference signals occupy orthogonal resources in multiuser beamforming, then channel estimation can be performed, but resource utilization is insufficient and system throughput is limited
Solution Approach 1:
The patent combines reference signals and data signals into the same time-frequency resources by superimposing them. The base station transmits both signals simultaneously on the same resource elements, and the terminal separates them using different spreading sequences. This merging eliminates the need for separate orthogonal resources for reference signals, thereby improving resource utilization and system throughput.
Solution Approach 2:
The patent makes the same time-frequency resources serve dual purposes: carrying both reference signals for channel estimation and data signals for information transmission. By using spreading sequences to differentiate the signals, the system achieves multi-functionality of the transmitted resources, resolving the contradiction between maintaining reference signal functionality and improving resource efficiency.
2Productivity
If data signals are superimposed on reference signals, then resource utilization improves, but interference between signals may increase
Solution Approach 1:
The patent introduces spreading sequences as an intermediary mechanism to separate reference signals and data signals in the code domain. Each signal type is assigned a unique spreading sequence, allowing the terminal to correlate and separate the superimposed signals effectively. This intermediary approach enables resource sharing while controlling interference through orthogonal or quasi-orthogonal spreading codes.
Solution Approach 2:
The patent changes the signal domain from purely time-frequency to include the code domain by applying spreading sequences. This parameter change allows signals to coexist in the same time-frequency resources by differentiating them through code orthogonality, thereby improving resource utilization while managing interference through code design.
3Ease of operation
If orthogonal spreading sequences are used for reference signals and data signals, then signal separation is enabled, but system complexity increases
Solution Approach 1:
The patent applies spreading sequences to reference signals and data signals before transmission at the base station. This preliminary action embeds the separation mechanism into the transmitted signal structure, allowing the terminal to perform simple correlation operations to separate the signals. The complexity is shifted to the transmission side, simplifying the reception side while maintaining signal separation capability.
Data Source
AI summary
The present invention provides a method of superimposing data signals and reference signals in a space division multiple access communication system, a base station of the communication system transmitting the first layer resource block and another layer resource block to a terminal using the same time/frequency resources, reference signals in the first layer resource block and reference signals in the other layer resource block being orthogonal to each other, the method including superimposing data signals transmitted in the first layer resource block at positions of reference signals in the first layer resource block, making a spreading sequence of the superimposed data signals orthogonal to a spreading sequence of the reference signals in the first layer resource block. The present invention can effectively use resources consumed under a multiuser MIMO system and drastically improve the system performance.