FDD Massive MIMO Backhaul Channel Estimation
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Solution Overview
Problem
Conventional wireless backhaul connections for small cells face limitations in range and flexibility due to radiated power requirements and alignment issues, especially under non-line-of-sight conditions and in all-weather scenarios, particularly with radio frequency and millimeter-wave technologies.
Innovation Solution
Implementing a Massive MIMO system with a frequency-division duplex (FDD) backhaul link for relay cells, utilizing a disproportionately large number of antennas to enable simultaneous and robust communication with multiple relay cells, and employing channel estimation methods involving long- and short-duration pilot signals to accurately determine uplink and downlink channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If radio frequency backhaul connections are used, then coverage range can be extended, but radiated power requirements increase significantly under non line-of-sight conditions
Solution Approach 1:
The patent combines multiple antenna elements into a MIMO array system, merging their individual capabilities to achieve spatial diversity and multiplexing gains. This allows the system to extend coverage range through spatial processing while managing radiated power requirements by distributing transmission across multiple antenna paths.
Solution Approach 2:
The patent transitions from traditional single-antenna or simple diversity systems to a multi-dimensional MIMO spatial domain. By utilizing multiple antennas in both transmit and receive arrays, the system creates additional spatial dimensions for signal transmission, enabling improved range and power efficiency through spatial processing techniques.
2Power
If millimeter-wave technology is used for backhaul, then high-gain directional communication is achieved, but line-of-sight requirements and alignment precision increase
Solution Approach 1:
The patent segments the communication function across multiple antenna elements rather than relying on a single high-gain directional antenna. This segmentation allows the system to achieve signal gain through array processing while maintaining adaptability to different propagation conditions and deployment scenarios through spatial diversity.
Solution Approach 2:
The MIMO array system provides multi-functionality by simultaneously supporting directional high-gain communication when needed and omnidirectional or multi-directional coverage in other scenarios. The same antenna array can be configured for different beamforming patterns, making the system universally adaptable to various deployment requirements without sacrificing signal gain.
3Ease of manufacture
If conventional wireless backhaul is used, then deployment simplicity is maintained, but reliability deteriorates in all-weather and non line-of-sight conditions
Solution Approach 1:
The MIMO system provides self-service through automatic channel estimation and adaptive spatial processing. The system autonomously adapts to varying propagation conditions by estimating channel state information and adjusting transmit/receive beamforming accordingly, maintaining reliability in all-weather conditions without requiring complex manual configuration or intervention.
Data Source
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AI summary
A central node of a MIMO system may transmit, to one or more communication terminals of the MIMO system, a long-duration downlink pilot signal carrying a pilot sequence having a first duration. The first duration may be equal to or greater than a quantity of antennas of the central node. The central node may receive retransmitted long-duration downlink pilot signals from the communication terminals. The central node may further transmit, to one or more communication terminals, a short- duration downlink pilot signal carrying a pilot sequence having a second duration. The second duration may be less than or equal to the quantity of antennas. The central node may receive a retransmitted short- duration downlink pilot signal from the one or more communication terminals. An uplink and downlink between the central node and one or more communication terminals may be estimated based on the received signals.