Downlink Reference Signal Orthogonalization for Multi-Layer Transmission
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Solution Overview
Problem
The existing LTE (Long Term Evolution) downlink reference signal structure is inadequate for supporting an increased number of transmission layers, which limits the efficiency and effectiveness of wireless communications.
Innovation Solution
A radio base station device and communication method that utilize orthogonal reference signals based on two-dimensional orthogonal codes to orthogonalize downlink reference signals in frequency, time, and between layers, allowing for an increase in the number of transmission layers and improving orthogonality between users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the existing LTE downlink reference signal structure is used, then the system maintains compatibility with current standards, but the number of transmission layers is limited and cannot be increased
Solution Approach 1:
The patent extends the reference signal structure from one dimension to two dimensions by introducing frequency-domain orthogonal codes in addition to time-domain orthogonal codes. This two-dimensional orthogonal code structure allows reference signals for multiple transmission layers to be orthogonalized both in time and frequency domains, enabling support for increased number of transmission layers while maintaining system compatibility
Solution Approach 2:
The patent segments the orthogonal code resources into two independent dimensions: time-domain orthogonal codes and frequency-domain orthogonal codes. This segmentation allows each dimension to independently contribute to the orthogonality of reference signals across different transmission layers, thereby scaling the system capacity without proportionally increasing overall complexity
2Productivity
If the number of transmission layers is increased, then communication capacity is improved, but orthogonality between reference signals becomes difficult to maintain
Solution Approach 1:
By introducing frequency-domain orthogonal codes as a second dimension complementing time-domain orthogonal codes, the patent creates a two-dimensional orthogonal code space. This extended space provides sufficient orthogonal resources to maintain reference signal orthogonality even when the number of transmission layers increases, thereby preserving communication reliability while enhancing capacity
Solution Approach 2:
The patent combines time-domain orthogonal codes and frequency-domain orthogonal codes into a composite orthogonal coding structure. This composite approach leverages the orthogonal properties of both dimensions simultaneously, creating a robust orthogonalization mechanism that can support increased transmission layers while maintaining signal integrity and orthogonality
Data Source
Figure 1(a)~1(b)
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AI summary
Provided is a downlink reference signal structure suitable for increase in number of transmission layers. A radio base station device (20) has a plurality of transmission antennas; a orthogonal RS sequence generator (22) for generating orthogonal reference signals based on a two-dimensional orthogonal code, the orthogonal reference signals being orthogonalized between downlink reference signals adjacent in two-dimensional directions of frequency direction and time direction to each other in one transmission layer and being orthogonalized in different transmission layers assigned to one radio resource; a multiplexer (23) for multiplexing transmission data and the orthogonal reference signals in the one transmission layer; and a transmitter for transmitting a transmission signal obtained by multiplexing the transmission data and the orthogonal reference signals, via the transmission antenna in transmission layers simultaneously.