Random Access Channel Basis Function Beamforming
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Solution Overview
Problem
In mmWave wireless communication systems, traditional array processing is not viable due to high power consumption by analog to digital and digital to analog converters, and RF beamforming is directional, making it difficult to receive random access channel (RACH) preambles from multiple users with omni-directional coverage while overcoming path loss.
Innovation Solution
The method involves a mobile device repeating the RACH preamble across different time intervals, where the access point listens on different orthogonal receive basis function beams, allowing for omni-directional reception and beam steering gain by summing signals across all beams, and using near-omni-directional basis function beams to ensure equal energy reception on all antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If traditional array processing is used in mmWave systems, then signal processing capability is provided, but power consumption by analog to digital and digital to analog converters becomes excessively high
Solution Approach 1:
The patent extracts and eliminates the need for multiple high-power analog-to-digital and digital-to-analog converters by using a single baseband processor to handle all antenna signals through virtual array processing, thereby dramatically reducing power consumption while maintaining signal processing capability
Solution Approach 2:
The patent replaces the physical hardware array processing mechanism with a mathematical/software-based virtual array processing approach, substituting mechanical/electrical complexity with computational algorithms that achieve the same beamforming and signal separation functions with much lower power consumption
2Adaptability or versatility
If RF beamforming is used, then directional signal reception is achieved, but omni-directional coverage for receiving RACH preambles from multiple users becomes difficult
Solution Approach 1:
The patent implements dynamic beamforming where the system adaptively forms different beams in different time intervals to cover all spatial directions, allowing the beam pattern to change dynamically over time to achieve omni-directional coverage while maintaining beam steering gain for each user
Solution Approach 2:
The patent uses periodic time-division beamforming where the access point sequentially steers beams through different directions in periodic time intervals, allowing each user to receive beam steering gain during their allocated time slot while the system collectively provides omni-directional coverage across all time intervals
3Productivity
If multiple users transmit RACH preambles simultaneously, then network access capacity is improved, but signal-to-noise ratio deteriorates due to interference and path loss
Solution Approach 1:
The patent segments the simultaneous multi-user RACH access into separate time intervals, with each user assigned to a specific time slot for preamble transmission. This temporal segmentation eliminates inter-user interference while maintaining high access capacity, and allows the system to apply dedicated beamforming to each user's signal to improve signal-to-noise ratio
Solution Approach 2:
The patent merges multiple single-antenna reception channels into a virtual array processing system that combines signals from multiple antenna elements through mathematical processing, thereby improving signal-to-noise ratio through spatial diversity and beamforming gain while supporting multiple users through time-division multiplexing
Data Source
AI summary
Systems, methods, apparatuses, and computer program products for random access channel (RACH) design using basis functions are provided. One method includes receiving, at an access point employing a receiver with Q antennas, a random access channel (RACH) preamble sent from a mobile unit. The receiving may comprise receiving the same RACH preamble at B different time intervals where the access point beamforms with a different beam selected from B basis function beams at each of the different time intervals.