Open-Loop Distributed Beamforming for Coherent Multi-Destination Links
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Solution Overview
Problem
Existing wireless communication systems in mobile ad-hoc networks face challenges in achieving coherent beamforming due to unknown or unestimable RF phases among participating emitters, leading to non-coherent waveform combination and reduced performance.
Innovation Solution
Implementing an open-loop distributed beamforming technique that utilizes a reference node for phase calibration, enabling one-way signaling to align transmit phases across nodes without requiring explicit channel state information feedback, and employing time-domain multiple access to mitigate frequency offset and support multiple destinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If distributed beamforming is implemented without phase calibration, then device complexity is reduced, but waveform coherence deteriorates leading to reduced performance
Solution Approach 1:
A reference node is introduced as an intermediary to facilitate phase calibration. The reference node transmits probe signals to source cluster nodes, which use these probes to determine phase offsets. This intermediary approach enables coherent beamforming without requiring complex direct phase synchronization between all source nodes and destination nodes, thus maintaining waveform coherence while managing system complexity.
2Measurement precision
If closed-loop beamforming with CSI feedback is used, then beamforming accuracy is improved, but communication overhead and latency increase
Solution Approach 1:
Phase calibration is performed in advance using open-loop probe signals before actual data transmission. The source cluster nodes determine phase offsets from reference node probes and store these calibration values for use during subsequent beamforming operations. This preliminary calibration eliminates the need for real-time CSI feedback during data transmission, reducing latency and communication overhead while maintaining beamforming accuracy.
3Adaptability or versatility
If omnidirectional antennas are used in MANET nodes, then network flexibility is maintained, but beamforming capability is reduced
Solution Approach 1:
The system transitions from spatial beamforming (requiring directional antennas) to temporal/phasedomain beamforming by using probe signals and phase calibration in the time and frequency domains. Source nodes apply determined phase offsets to their transmitted signals, creating coherent beamforming capability with omnidirectional antennas. This dimensionality change allows beamforming functionality to be achieved through signal processing rather than physical antenna orientation.
Data Source
AI summary
Devices, systems and methods for collaborative wireless communication in a wireless network are described. One example method includes performing a bidirectional communication with a reference node in the source cluster, receiving, from a destination cluster comprising a second plurality of nodes, a probe generated using a phase associated with the destination cluster, estimating, based on a propagation delay of the probe, a delay parameter, generating, based on the phase associated with the destination cluster and the delay parameter, a channel estimate, and transmitting, to each of the second plurality of nodes, a common message generated using a phase value and a delay value, wherein the phase value and the delay value are derived based on the channel estimate, and wherein the destination cluster is remotely located from the source cluster.