Base Station Reference Signal Multiplexing for LTE-A Compatibility
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Solution Overview
Problem
In LTE systems, efficiently transmitting reference signals to user apparatuses with different numbers of physical antennas within the same cell is challenging, particularly when transitioning from LTE to LTE-Advanced systems, as it requires backward compatibility and optimal utilization of radio resources.
Innovation Solution
The base station apparatus divides its multiple physical antennas into two groups and categorizes radio resources into two resource blocks, each containing a specific arrangement of reference signals, allowing LTE and LTE-A user apparatuses to measure channel conditions using compatible reference signals, ensuring backward compatibility and efficient resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reference signals are transmitted using a fixed arrangement for LTE systems, then backward compatibility is maintained, but radio resource utilization efficiency deteriorates when LTE-A users are present
Solution Approach 1:
The reference signal arrangement is made dynamic by switching between a first arrangement (for LTE compatibility) and a second arrangement (for LTE-A efficiency) based on whether LTE-A user apparatus are present in the cell. This dynamic adaptation resolves the contradiction by allowing the system to optimize resource utilization when needed while maintaining backward compatibility when LTE-A users are absent.
2Productivity
If resource blocks are allocated dynamically between LTE and LTE-A users, then radio resource utilization efficiency improves, but system complexity increases due to multiple reference signal arrangements
Solution Approach 1:
The resource blocks are segmented into two distinct groups: a first group using a reference signal arrangement compatible with LTE systems, and a second group using an arrangement optimized for LTE-A systems. This segmentation allows the base station to allocate appropriate resource block groups to different user types, improving overall resource utilization while managing complexity through structured organization.
Solution Approach 2:
The base station implements a universal reference signal transmission capability that can adapt to both LTE and LTE-A user apparatus. By maintaining multiple reference signal arrangements and selecting the appropriate one based on user type, the system achieves multi-functionality, serving both legacy and advanced users efficiently without requiring separate systems.
3Measurement precision
If separate resource blocks are allocated for LTE and LTE-A users, then channel condition measurement accuracy improves, but loss of radio resources increases due to dedicated reference signals
Solution Approach 1:
Different reference signal arrangements are applied locally to different resource block groups based on the specific needs of the allocated user apparatus. LTE user apparatus receive reference signals in arrangements optimized for their capabilities, while LTE-A users receive arrangements that enable advanced features. This local optimization improves measurement accuracy for each user type without unnecessarily deploying complex arrangements system-wide, thereby reducing overall resource loss.
Data Source
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AI summary
A base station apparatus includes multiple antennas including M physical antennas (#1, #3, #5, #7) of a first group and M physical antennas (#2, #4, #6, #8) of a second group; a reference signal multiplexing unit which multiplexes at least M types of reference signals (P#1-P#4) to resource blocks of a downlink signal; and a transmitting unit which wirelessly transmits the downlink signal. The M types of reference signals are multiplexed to a first resource block and a second resource block in the same arrangement pattern. The M types of reference signals (P#1-P#4) within the first resource block are transmitted from the physical antennas (#1, #3, #5, #7) of the first group. The M types of reference signals within the second resource block are transmitted from the physical antennas (#2, #4, #6, #8) of the second group.