Distributed Radio Clock Dithering With Synchronized FSMs
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Solution Overview
Problem
Distributed radio systems face challenges in maintaining a high signal-to-noise ratio (SNR) during clock transfer due to radiated power limitations imposed by electromagnetic interference (EMI) and radio frequency interference (RFI) regulations, which can be exacerbated by dithering methods that fail to account for temporal shifting of clock edges, leading to reduced bandwidth and synchronization issues.
Innovation Solution
Implementing faster dithering with synchronized Finite State Machines (FSMs) in both primary and secondary radio heads (RHs) to provide exact dithering parameters, ensuring phase information is maintained without limiting bandwidth, by using identical FSMs in secondary RHs to learn the dithering sequence from the primary RH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dithering is applied to clock signal transfer, then spectral purity and random jitter performance improve, but bandwidth is reduced and synchronization issues occur due to temporal shifting of clock edges
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing Finite State Machines in both primary and secondary radio heads before dithering begins. This ensures that all system components are ready to handle the temporal shifts caused by dithering, preventing synchronization issues while maintaining the spectral purity benefits of dithering.
Solution Approach 2:
The patent implements feedback mechanisms where secondary radio heads learn dithering sequences from primary radio heads and adjust their local oscillators accordingly. This feedback loop compensates for temporal shifting effects, maintaining synchronization while allowing dithering to improve spectral purity.
2Measurement precision
If dithering is applied to clock signal transfer, then spectral purity and random jitter performance improve, but synchronization issues occur due to temporal shifting of clock edges
Solution Approach 1:
The system performs preliminary synchronization of Finite State Machines before enabling dithering. This preparatory step ensures all radio heads are synchronized and ready to handle the temporal variations introduced by dithering, maintaining reliability while improving random jitter performance.
Solution Approach 2:
Secondary radio heads copy the dithering sequence information from primary radio heads. By replicating the same dithering pattern across all system components, the patent maintains synchronization while benefiting from the improved random jitter performance that dithering provides.
3Adaptability or versatility
If faster dithering is implemented, then clock spreading capability increases, but complexity of coordinating dithering sequences across multiple radio heads increases
Solution Approach 1:
The patent implements universal Finite State Machines with identical functionality across all primary and secondary radio heads. This universality allows faster dithering rates to be coordinated easily, as each radio head independently executes the same dithering logic, reducing coordination complexity while enhancing clock spreading capability.
Solution Approach 2:
Each radio head autonomously generates and applies dithering sequences based on its local Finite State Machine, rather than requiring centralized coordination. This self-service approach enables faster dithering rates while minimizing the complexity of coordinating dithering sequences across multiple radio heads.
Data Source
AI summary
A radio-head apparatus can comprise memory to store dithering information of the apparatus. The radio-head can further include radio-head circuitry to generate a clock signal according to the dithering information and to provide a wakeup signal, subsequent to commencement of clock signal generation, to instruct a secondary RH to use the clock signal of the RH. The same wakeup signal is also used to synchronize the finite state machines of both RHs that govern and report the dithering information. Synchronization of the FSM allows estimation of information to be used in the secondary RH for compensation of the clock dithering applied in the primary RH. Other systems and apparatuses are described.