Dynamic Bandwidth Allocation in Coherent Optical Access Networks
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Solution Overview
Problem
Conventional optical access networks face challenges in meeting the increasing demand for upstream bandwidth efficiency and improving packet delay characteristics, particularly due to the limitations of intensity modulation and direct detection methods.
Innovation Solution
The implementation of a dynamic bandwidth allocation method in a coherent optical access network, which dynamically controls the modulation and coding schemes based on the communication channel quality by measuring the received optical power and using pre-defined mapping tables to determine the appropriate modulation and coding scheme.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If intensity modulation and direct detection methods are used, then implementation is simple and cost-effective, but upstream bandwidth efficiency and packet delay characteristics deteriorate
Solution Approach 1:
The patent changes the modulation and coding scheme parameters dynamically based on channel quality. By selecting different modulation orders (e.g., QPSK, 16-QAM, 64-QAM) and coding rates, the system optimizes upstream bandwidth efficiency while maintaining implementation feasibility through standardized coherent detection techniques.
Solution Approach 2:
The patent introduces dynamic bandwidth allocation that adjusts modulation and coding schemes in real-time based on channel conditions. The transport node dynamically selects MCS indices and allocates bandwidth accordingly, transforming the static intensity modulation system into a dynamic coherent system that adapts to varying channel quality.
2Use of energy by moving object
If intensity modulation and direct detection methods are used, then power consumption is low, but performance requirements for increasing transmission bandwidth are not met
Solution Approach 1:
The patent adjusts modulation order and coding rate parameters based on received optical power measurements. When channel quality is good, higher-order modulation (e.g., 64-QAM) is used to increase data rate. When quality degrades, lower-order modulation (e.g., QPSK) is selected, maintaining reliable transmission across varying power conditions.
Solution Approach 2:
The system performs preliminary channel quality assessment by measuring received optical power before transmitting data. Based on this preliminary measurement, the transport node pre-determines the appropriate modulation and coding scheme, ensuring optimal performance before actual data transmission begins.
3Productivity
If coherent optical communication technology is applied, then spectral efficiency and receiver sensitivity improve, but optical complexity and cost increase
Solution Approach 1:
The patent makes the coherent detection system universally adaptable by implementing dynamic selection of modulation and coding schemes. The same coherent detection infrastructure can handle multiple modulation formats (QPSK, 16-QAM, 64-QAM) and coding rates, making the system versatile for different service requirements and channel conditions without requiring separate hardware for each mode.
Solution Approach 2:
The patent manages optical complexity by dynamically adjusting modulation parameters rather than deploying fixed high-complexity systems. By selecting appropriate modulation orders and coding rates based on actual channel quality, the system achieves high spectral efficiency only when necessary, reducing overall system complexity compared to always using maximum-order modulation.
4Ease of operation
If fixed modulation and coding schemes are used, then system operation is simple, but bandwidth efficiency and packet delay characteristics deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the transport unit measures received optical power and reports channel quality information to the transport node. Based on this feedback, the transport node dynamically adjusts the modulation and coding scheme for subsequent transmissions, optimizing bandwidth efficiency while maintaining operational simplicity through automated closed-loop control.
Solution Approach 2:
The system transitions from static fixed modulation schemes to dynamic adaptive modulation and coding. The transport node dynamically selects MCS indices based on real-time channel quality feedback, enabling the system to adapt to varying bandwidth requirements and channel conditions without manual intervention.
Data Source
AI summary
Proposed is an apparatus and method of dynamic bandwidth allocation for a coherent optical communication having a variable modulation and coding scheme in an optical access network, wherein the method includes determining an index of a received signal quality (IRSQ) by measuring a received optical power (ROP) for downstream transmission, receiving a message of granting authority from a transport node (TN), transmitting a message of a buffer status report (BSR) to the TN in response to the message of grating authority, receiving from the TN a message of bandwidth allocation (BA) including an index of a modulation and coding scheme (IMCS), and determining a modulation and coding scheme (MCS) corresponding to the index of the modulation and coding scheme (IMCS) on the basis of the BA message.