Beamforming Synchronization Using Repeated Pilots Under High Pathloss
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Solution Overview
Problem
Millimeter Wave (mmW) beamforming systems face challenges in synchronization due to high pathloss and the need for efficient resource utilization, as existing solutions do not adequately address time-frequency and spatial synchronization, leading to increased overhead and complexity in channel estimation and device identification.
Innovation Solution
A beamforming system synchronization architecture that uses periodically configured time-frequency resource blocks with repeated pilot signals for all stages of synchronization, including initial coarse synchronization, device identification, and channel estimation, employing Inverse Fast Fourier Transfers (IFFTs) and cyclic prefixes to simplify the detection process at receiving devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple pilot signals are used for time-frequency synchronization and channel estimation, then synchronization accuracy and channel estimation performance are improved, but system overhead increases
Solution Approach 1:
The patent merges multiple pilot signal functions into a single integrated synchronization signal structure. The same signal serves for time synchronization, frequency synchronization, and channel estimation simultaneously, eliminating the need for separate pilot signals for each function and thereby reducing system overhead while maintaining measurement precision
Solution Approach 2:
The synchronization signal is designed with multi-functionality to perform time-frequency synchronization and channel estimation in a single signal. By making the signal universal for multiple purposes, the patent avoids redundant signaling and reduces the overall quantity of pilot signals required in the system
2Power
If directional transmissions with narrow beams are used, then beamforming gains and data rates are improved, but synchronization complexity and vulnerability to channel variations increase
Solution Approach 1:
The patent employs preliminary action by transmitting synchronization signals before actual data communication begins. This allows receiving devices to establish time-frequency synchronization and channel estimates in advance using the synchronization signal, so that when directional data transmissions start, the devices are already synchronized and can process the narrow beam data efficiently without increased complexity
Solution Approach 2:
The synchronization signal acts as an intermediary that bridges the transmitter and receiver before actual data transmission. It provides a common reference signal that both ends can use to align their time and frequency references and estimate channels, thereby simplifying the synchronization process even when narrow directional beams are used for data communication
3Reliability
If existing synchronization solutions are used in mmW beamforming systems, then device identification and basic synchronization are achieved, but spatial synchronization is not considered and resource utilization is inefficient
Solution Approach 1:
The patent extends synchronization from the traditional time-frequency domain to include the spatial dimension. By adding spatial synchronization capability to the existing time-frequency synchronization framework, the system can now handle beamforming operations in mmW frequencies where directional spatial alignment is critical, thereby improving adaptability while maintaining reliable device identification
Data Source
AI summary
A beamforming system synchronization architecture is proposed to allow a receiving device to synchronize to a transmitting device in time, frequency, and spatial domain in the most challenging situation with very high pathloss. A periodically configured time-frequency resource blocks in which the transmitting device uses the same beamforming weights for its control beam transmission to the receiving device. A pilot signal for each of the control beams is transmitted in each of the periodically configured time-frequency resource blocks. Pilot symbols are inserted into pilot structures and repeated for L times in each pilot structure. The L repetitions can be implemented by one or more Inverse Fast Fourier Transfers (IFFTs) with corresponding one or more cyclic prefix (CP) lengths.