Base Station Reference Signal Allocation for LTE-LTE+ Coexistence
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Solution Overview
Problem
LTE terminals do not recognize reference signals (RSs) allocated to LTE+ terminals, leading to incorrect signal reception and deteriorated performance when both types of terminals coexist, as LTE terminals mistakenly receive RSs intended for LTE+ terminals, causing error rate and throughput issues.
Innovation Solution
A method where first reference signals are allocated to all resource blocks for both LTE terminals and LTE+ terminals, while second reference signals are allocated to part of the resource blocks specifically for LTE+ terminals, allowing for distinct allocation patterns based on subframes to prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reference signals are allocated to all resource blocks for LTE+ terminals, then LTE+ terminals can achieve high-speed transmission with 8 antennas, but LTE terminals mistakenly receive these RSs as data signals causing error rate deterioration
Solution Approach 1:
The patent segments reference signal allocation by terminal type: LTE terminals receive cell-specific RSs (CRS) on all resource blocks for reliable reception, while LTE+ terminals receive additional CRS plus terminal-specific RSs (UE-RS) on allocated resource blocks for high-speed transmission. This segmentation allows each terminal type to receive appropriate RSs without interference.
Solution Approach 2:
The patent applies local quality by making RS allocation patterns different for different terminal types and resource blocks. LTE terminals use CRS on all RBs with specific patterns, while LTE+ terminals use CRS plus UE-RS on allocated RBs. The base station transmits different RS patterns to different terminals based on their capabilities and allocation.
2Productivity
If reference signals are transmitted from all 8 antennas, then LTE+ terminals can perform MIMO transmission for high throughput, but LTE terminals cannot correctly receive signals designed for 4 antennas
Solution Approach 1:
The patent makes the base station universally compatible with both LTE and LTE+ terminals by transmitting CRS that both terminal types can use, while additionally providing UE-RS for LTE+ terminals. The same base station infrastructure supports both 4-antenna and 8-antenna operations through different RS allocation patterns.
Solution Approach 2:
The patent enables dynamic RS allocation where the base station adaptively transmits different RS patterns (CRS only for LTE terminals, CRS plus UE-RS for LTE+ terminals) based on terminal capability and resource block allocation. This dynamic approach allows the system to optimize for each terminal type while maintaining compatibility.
3Reliability
If reference signals are allocated to part of resource blocks only for LTE+ terminals, then LTE terminals can maintain correct signal reception, but LTE+ terminals cannot achieve high-speed transmission with full 8 antenna utilization
Solution Approach 1:
The patent segments RS allocation into two layers: CRS on all resource blocks for reliable reception by both terminal types, and UE-RS on allocated resource blocks specifically for LTE+ terminals to enable high-speed MIMO transmission. This dual-layer segmentation resolves the contradiction between reliability and speed.
Data Source
AI summary
Disclosed is a wireless communication base station apparatus whereby it is possible to prevent degradation of throughput of LTE terminals, even when LTE terminals and LTE+ terminals are present together. In this apparatus, a setting section (105) sets in each subframe a resource block in which is arranged a reference signal that is employed solely by LTE+ terminals, based on the pattern of arrangement of reference signals employed solely by LTE+ terminals. In the case of symbols that are mapped to antennas (110-1) to (110-4), an arrangement section (106) arranges the characteristic cell reference signals employed by both LTE terminals and LTE+ terminals in all of the resource blocks in a single frame. In contrast, in the case of the symbols that are mapped to the antennas (110-5) to (110-8), the arrangement section (106) arranges in some of the resource blocks, that are set in accordance with the setting results input from a setting section (105), the characteristic cell reference signals that are employed solely by the LTE+ terminals.