Reference Signal Overhead Reduction in 5G Spatial Modulation
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Solution Overview
Problem
The multi-carrier spatial modulation (SM) technique faces significant overheads in downlink physical channel training, which decreases system spectral efficiency due to the need for accurate channel state information and synchronization between multiple antennas, especially as the number of antennas increases.
Innovation Solution
The solution involves inserting physical resource blocks to reduce reference signal overheads by superimposing data symbols and reference signals, using data symbols as supplementary reference signals, and employing self-adaptive resource mapping and non-periodic insertion of conventional and reduced physical resource blocks to optimize channel estimation and training efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional reference signal transmission is used in multi-carrier spatial modulation systems, then channel estimation can be performed, but training overheads increase and spectral efficiency decreases
Solution Approach 1:
The patent combines reference signals and data symbols into the same time-frequency resources through superposition. The transmitted signal is formulated as y = h*x + w, where reference signals and data symbols are superimposed with different power scaling factors. This merging allows simultaneous channel estimation and data transmission, reducing training overhead while maintaining channel estimation accuracy.
Solution Approach 2:
The patent makes data symbols serve dual functions: as data carriers and as supplementary reference signals for channel estimation. By using data symbols with known structure and power scaling, they can function as additional training pilots, especially in scenarios where traditional reference signals are reduced or removed, thereby improving spectral efficiency without sacrificing channel estimation capability.
2Measurement precision
If more reference signals are transmitted for accurate channel estimation, then channel state information quality improves, but frequency resource overhead increases
Solution Approach 1:
The patent enables data symbols to serve themselves as reference signals for channel estimation. By utilizing the inherent structure and power properties of data symbols, the system performs self-channel-estimation without requiring additional dedicated reference signal resources. The data symbols inherently contain information that can be used for channel estimation when properly scaled and processed.
3Measurement precision
If conventional physical resource blocks are used for channel training, then training accuracy is maintained, but resource efficiency decreases
Solution Approach 1:
The patent dynamically adjusts the mixing ratio between reference signals and data symbols based on channel conditions, signal-to-noise ratio, and system requirements. The power scaling factors for reference signals and data symbols are optimized adaptively to maintain training accuracy while minimizing resource overhead. This dynamic approach allows the system to flexibly trade off between training accuracy and resource efficiency depending on operational conditions.
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AI summary
The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method for transmitting reference signals is provided. In the method, a transmitting apparatus inserts at least one physical resource block for reducing reference signal overheads between adjacent first physical resource blocks, and then transmits first physical resource blocks and the at least one physical resource block for reducing the reference signal overheads. Also disclosed are methods and apparatuses for transmitting and receiving reference signals in the physical resource blocks for reducing the reference signal overheads, such that training overheads can be effectively decreased, and overheads caused by downlink physical channel training can be reduced, resulting in an improved system spectral efficiency.