OFDM-PON Upstream Registration and Ranging Method
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Solution Overview
Problem
The existing registration and ranging methods in PON systems are not applicable to OFDM-PON systems due to the separate registration and ranging processes, which are not feasible in OFDM technology, and the delay between the MAC and physical layers is not fixed, causing collisions and inefficiencies.
Innovation Solution
A method involving a central office device and a terminal device that uses an upstream registration window with a correlation sequence symbol and OFDM symbols, where the correlation sequence symbol meets specific peak-to-average ratio conditions, and access information is modulated using differential phase modulation in the frequency domain, allowing for simultaneous upstream registration and ranging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate registration and ranging processes are used in PON systems, then registration can be completed with acknowledgment mechanisms, but at least two upstream windows greater than propagation delay are needed, increasing time consumption
Solution Approach 1:
The patent combines registration and ranging operations into a single integrated process. The ONU sends both registration information and ranging information (timestamp) simultaneously in one upstream transmission window, and the OLT processes both functions together, eliminating the need for separate registration and ranging windows that would otherwise be required.
Solution Approach 2:
The upstream transmission window is designed to serve multiple functions simultaneously: it carries both registration requests and ranging timestamps. The OLT's response window similarly serves dual purposes by providing both registration acknowledgments and ranging adjustments, making the communication protocol more efficient and reducing the number of separate communication rounds needed.
2Adaptability or versatility
If traditional PON registration and ranging methods are applied to OFDM-PON systems, then the methods cannot be applied due to non-fixed delay between MAC and physical layers, causing collisions and inefficiencies
Solution Approach 1:
The patent adapts the registration and ranging mechanism to OFDM-PON by changing the timing reference parameters. Instead of relying on fixed delays between MAC and physical layers, the system uses timestamp-based ranging where the ONU records the exact OFDM symbol boundary timestamp and the OLT calculates round-trip time based on these precise timing references, accommodating the variable delays inherent in OFDM processing.
Solution Approach 2:
The system dynamically adjusts to the actual transmission delays observed in OFDM-PON operations. Rather than assuming fixed delays, the ranging process continuously measures and compensates for the actual variable delays between MAC layer timestamp generation and physical layer transmission/reception, making the system adaptive to changing conditions and OFDM-specific timing characteristics.
Data Source
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AI summary
Embodiments of the present invention disclose a terminal device registration method and a device. The method includes: sending upstream registration window information to a terminal device, where the upstream registration window information is used to indicate a starting position of an upstream registration window to the terminal device; receiving an upstream access signal sent by the terminal device from the starting position of the upstream registration window, where the upstream access signal includes a correlation sequence symbol and at least one OFDM symbol following the correlation sequence symbol, the correlation sequence symbol is constituted by a first sequence that meets a preset condition, and the at least one OFDM symbol is used to modulate access information by means of differential phase modulation in a frequency domain; and performing upstream ranging according to the starting position of the upstream registration window and the correlation sequence symbol, so as to obtain an upstream ranging result. In the embodiments of the present invention, upstream registration and upstream ranging can be implemented in an OFDM PON system.