Selective Pilot Signal Transmission for MIMO Channel Estimation
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Solution Overview
Problem
Existing wireless communication systems, such as LTE and UMTS, face challenges in supporting 4×4 MIMO transmissions due to the need for additional pilot signals, which can interfere with legacy UEs and reduce energy availability for data transmission, leading to performance degradation for non-legacy UEs when pilot powers are minimized.
Innovation Solution
The system selectively transmits common and demodulation pilot signals, with legacy common pilot signals at higher powers and non-legacy common pilot signals at lower powers, and adjusts pilot powers based on UE capabilities and environmental conditions to enhance demodulation performance while minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional non-legacy common pilot signals are transmitted to support 4x4 MIMO transmissions, then channel estimation capability is improved, but interference with legacy UEs increases and energy availability for data transmission decreases
Solution Approach 1:
The patent segments pilot signal transmission by identifying and separating legacy common pilot signals from non-legacy common pilot signals. The base station determines which UEs are legacy and which are non-legacy, then transmits different pilot signal sets accordingly. This segmentation allows channel estimation for 4x4 MIMO while minimizing interference to legacy UEs by avoiding unnecessary pilot transmissions to them.
Solution Approach 2:
The patent applies local quality by transmitting non-legacy common pilot signals only to non-legacy UEs that require 4x4 MIMO support, while legacy UEs continue to receive only legacy common pilot signals. This localized approach ensures that enhanced channel estimation capability is provided only where needed, without causing widespread interference.
2Use of energy by moving object
If pilot signal powers are minimized to increase energy availability for data transmission, then energy efficiency is improved, but demodulation performance deteriorates
Solution Approach 1:
The patent changes the power allocation parameter dynamically based on UE type and transmission conditions. Non-legacy common pilot signals are transmitted at reduced power levels compared to legacy common pilot signals, optimizing the balance between energy efficiency and demodulation performance. The base station adjusts pilot signal powers according to the specific requirements of each UE type.
3Adaptability or versatility
If legacy common pilot signals are transmitted at higher powers, then compatibility with legacy UEs is maintained, but energy consumption increases
Solution Approach 1:
The patent segments the UE population into legacy and non-legacy categories, allowing differentiated power allocation. Legacy UEs receive higher power common pilot signals to maintain compatibility, while non-legacy UEs receive lower power non-legacy common pilot signals. This segmentation reduces overall energy consumption compared to transmitting high-power pilot signals to all UEs.
Data Source
AI summary
Multiple antennas employed at transmitting and receiving nodes can significantly increase a MIMO system capacity, especially when channel knowledge of link(s) between the transmitting and receiving nodes is available at the transmitting node. Channel knowledge may be acquired through feedback provided by the receiving node based on a plurality of common pilots transmitted by the transmitting node. The common pilots may include legacy and non-legacy pilots. If the feedback indicates that data demodulation at the receiving node can be enhanced, the transmitting node may also transmit demodulation pilot signal(s), which may coincide with the transmission of data. The receiving node can use the demodulation pilot signal(s), alone or with the common pilot signal(s), to demodulate data received from the transmitting node. The transmitting node may notify the receiving node to monitor for the demodulation pilot signal(s) through higher layer signaling and/or scheduling orders over a control channel.