Spatial Beamforming Modulation for mmWave Path Loss
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Solution Overview
Problem
Millimeter Waves (mmWaves) face high propagation loss and poor penetration through objects, making spatial multiplexing and spatial modulation impractical due to their unique propagation characteristics, particularly in urban environments where beams with different angles of departure result in distinct patterns of angles of arrival.
Innovation Solution
Spatial beamforming modulation is employed, using the angle of departure (AoD) of transmission beams as an additional source of information, with pilot transmissions enabling channel estimation and mapping between AoDs and symbol values, allowing for adaptive modulation schemes based on channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spatial multiplexing is used to transmit independent data signals from multiple antennas, then data rate increases, but it becomes impractical due to large path loss in mmWave spectrum
Solution Approach 1:
The patent transitions from traditional spatial multiplexing in the spatial domain to spatial beamforming modulation that exploits the angular domain. By mapping data symbols to specific angles of departure (AoD) through beamforming, the system creates a new dimension for information transmission that is suitable for mmWave channels with high path loss.
Solution Approach 2:
The patent changes the transmission parameter from simple antenna indexing to controlled angles of departure. By adjusting the AoD parameter through beamforming weights, the system can direct energy along specific paths, thereby overcoming the path loss problem while still utilizing multiple antennas for increased data rate.
2Productivity
If spatial modulation is used with antenna index as information source, then spectral efficiency improves, but mmWave transmissions from different antennas become indistinguishable due to dense packing
Solution Approach 1:
The patent moves the modulation dimension from antenna index selection to angle of departure control. Instead of relying on which antenna transmits (spatial modulation), the system uses which angle the beam forms (beamforming), creating distinguishable transmission patterns even with densely packed antennas.
Solution Approach 2:
The patent segments the spatial domain into distinct angular sectors through beamforming. Each data symbol is mapped to a specific AoD sector, creating well-separated transmission beams that are easily distinguishable at the receiver, thereby solving the indistinguishability problem of dense antenna packing.
3Loss of energy
If directional beamforming is used to achieve high gains, then propagation loss is compensated, but spatial modulation methods become impractical
Solution Approach 1:
The patent merges the benefits of directional beamforming (energy concentration for path loss compensation) with data transmission by embedding information in the AoD selection. This combination creates spatial beamforming modulation, which achieves both energy efficiency and high data rates suitable for mmWave communications.
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 increases transmission rates by leveraging multiple antennas for directional beamforming, enhancing spectral efficiency and uniqueness of signal patterns, while adapting to varying channel gains for improved data transmission in mmWave communication.
Implementation Method 1
a plurality of antennas for beamforming with different angles of departure (AoD)
Implementation Method 2
the modulator is to cause the plurality of antennas to perform pilot transmission with transmission beams having different AoDs to enable at least one receiver to estimate a pattern of arrival impinging upon antennas of the receiver for different transmission beams
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A transmitter includes a plurality of antennas for beamforming with different angles of departure (AoD), an information interface to receive a sequence of symbols including a first symbol and a second symbol and a modulator to cause the plurality of antennas to form a transmission beam with an AoD selected according to a value of the first symbol and modulated according to a value of the second symbol.