MIMO Transmitter Polarization for Interference Reduction
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Solution Overview
Problem
Distributed antenna systems face interference issues due to lack of spatial separation in MIMO communications signals, especially in line-of-sight configurations, leading to performance degradation and limited coverage, particularly at higher frequencies.
Innovation Solution
Configuring multiple MIMO transmitters in remote units with multiple antennas to transmit in different polarization states, and employing phase shifting to provide phase separation between signals received by MIMO receivers, allowing for improved spatial separation and reduced interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple MIMO transmitters are configured in line-of-sight (LOS) to provide higher frequency signals for larger channel bandwidth, then data throughput increases, but spatial separation is reduced causing interference and performance degradation
Solution Approach 1:
The patent introduces polarization as an additional dimension for signal separation. Instead of relying solely on spatial separation in the horizontal plane, the system uses vertical polarization states (e.g., vertical and horizontal polarizations) to differentiate between multiple data streams. This allows MIMO transmitters to operate in LOS configuration while maintaining distinguishable signal paths through polarization diversity.
Solution Approach 2:
The patent changes the signal parameter from spatial position to polarization state. By modulating signals with different polarization orientations, the system enables the MIMO algorithm to distinguish between multiple data streams even when transmitters are closely spaced in LOS configuration, thus resolving the interference issue while maintaining high data throughput.
2Area of stationary object
If remote units are arranged for line-of-sight (LOS) communications to allow higher frequencies, then channel bandwidth increases, but antenna isolation requirements increase leading to device complexity
Solution Approach 1:
The patent changes the differentiation parameter from spatial separation distance to polarization state. This allows the system to maintain coverage area with LOS configurations while reducing antenna isolation requirements, as polarization diversity provides signal separation without requiring large physical distances between antennas.
3Area of stationary object
If MIMO transmitters are closely located to improve spatial efficiency, then device density increases, but phase separation is reduced causing interference
Solution Approach 1:
The patent compensates for reduced spatial phase separation by introducing polarization as another dimension. Even when transmitters are closely located, signals maintain distinguishable polarization states that provide sufficient phase separation for the MIMO algorithm to function effectively, thus preserving spatial efficiency without losing signal information.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances high-data rate wireless coverage and efficiency, particularly at higher frequencies, by enabling more effective phase separation and reducing the need for high antenna isolation, thereby improving communication performance and coverage area.
Implementation Method 1
Configuring multiple MIMO transmitters in remote units with multiple antennas to transmit in different polarization states
Data Source
AI summary
Components, systems, and methods for reducing location-based interference in distributed antenna systems operating in multiple-input, multiple-output (MIMO) configuration are disclosed. Interference is defined as issues with received MIMO communications signals that can cause a MIMO algorithm to not be able to solve a channel matrix for MIMO communications signals received by MIMO receivers in client devices. These issues may be caused by lack of spatial (i.e., phase) separation in the received MIMO communications signals. Thus, to provide phase separation of received MIMO communication signals, multiple MIMO transmitters are each configured to employ multiple transmitter antennas, which are each configured to transmit in different polarization states. In certain embodiments, one of the MIMO communications signals is phase shifted in one of the polarization states to provide phase separation between received MIMO communication signals. In other embodiments, multiple transmitter antennas in a MIMO transmitter can be offset to provide phase separation.