SSB Auxiliary Sequences for Fast Sub-THz Beam Acquisition
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Solution Overview
Problem
Existing 5G New Radio (NR) systems face challenges in fast beam acquisition at sub-THz band due to high path-loss and large overhead in beam sweeping, particularly in initial access procedures and reference signal configurations, with limited deployment and utilization in synchronization signal-physical broadcast channel (SSB) transmission.
Innovation Solution
Implementing an SSB pattern with auxiliary sequences transmitted on overlapping wide beams, using different time slots or frequencies, to facilitate fast beam acquisition by considering beam steering delay, wide bandwidth, and RF chain availability, enabling methods for initial access processes and reducing overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If beam sweeping is performed to acquire narrow beams in sub-THz band, then beamforming gain is improved, but overhead increases significantly
Solution Approach 1:
The patent segments the beam acquisition process into two stages: first transmitting wide beams for initial signal detection, then transmitting narrow beams only in directions where signals were detected. This segmentation reduces overhead by avoiding unnecessary narrow beam transmissions in directions without signals, while maintaining beamforming gain where needed.
Solution Approach 2:
The patent performs preliminary action by first transmitting wide beams to detect signal presence before committing to narrow beam transmissions. This preliminary wide beam transmission stage provides directional information that guides subsequent narrow beam transmissions, reducing overall overhead while preserving beamforming gain in relevant directions.
2Speed
If narrow beams are acquired directly from wide beams without additional sweeping, then beam acquisition speed is improved, but measurement precision may deteriorate
Solution Approach 1:
The patent implements feedback by having the UE measure signal strengths from wide beams and feed this information back to the gNodeB. The gNodeB uses this feedback to determine which directions require narrow beam transmissions, enabling fast beam acquisition while maintaining precision through targeted narrow beam transmissions only where signals were detected.
Solution Approach 2:
The patent applies partial action by transmitting narrow beams only in directions where wide beam signals were detected, rather than performing complete beam sweeping. This partial approach speeds up acquisition by skipping unnecessary directions while maintaining sufficient precision through the targeted narrow beam transmissions in relevant directions.
3Device complexity
If hierarchical beam sweeping is used to reduce overhead, then overhead is reduced, but beam acquisition time increases
Solution Approach 1:
The patent performs preliminary wide beam transmissions before narrow beam transmissions, allowing the UE to detect signals and provide feedback quickly. This preliminary action enables the gNodeB to immediately start narrow beam transmissions in promising directions without waiting for complete hierarchical sweeping, reducing overall acquisition time while maintaining reduced overhead.
Solution Approach 2:
The patent introduces dynamic adaptation where the gNodeB adjusts the beam acquisition process based on real-time UE feedback about wide beam signal strengths. This dynamic approach allows the system to flexibly switch between wide and narrow beam transmissions based on actual signal conditions, optimizing both overhead reduction and time efficiency.
Data Source
AI summary
Methods and devices are provided in which a synchronization signal block (SSB) pattern is transmitted on overlapping wide beams that include one or more auxiliary sequences that do not include physical broadcast channel (PBCH) payload. The auxiliary sequences may be transmitted on different time slots, for example different OFDM symbols, or different frequencies, or both. In some embodiments, for each SSB transmission, auxiliary sequences may be sent on a same frequency as the SSB, but different time slots or OFDM symbols. In some embodiments, the one or more auxiliary sequences are sent on the same time slot or OFDM symbol, but via a different radio frequency (RF) chain.