Cable Modem SBC for VoIP DQoS Allocation
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Solution Overview
Problem
VoIP devices without NCS messaging capabilities or embedded in local area networks supported by cable modems lack access to Dynamic Quality of Service (DQoS) mechanisms, which are essential for ensuring reliable VoIP services by managing bandwidth allocation and commitment within HFC networks.
Innovation Solution
A cable modem integrated session border control circuit operates between a local area network and a DOCSIS network, utilizing Session Initiation Protocol (SIP) messages to communicate with the Cable Modem Termination System (CMTS) for dynamic service flow management, enabling DQoS allocation and commitment without requiring NCS messaging or PCMM network infrastructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DOCSIS Dynamic Service Flow messages are used to request bandwidth allocation, then QoS for VoIP is improved, but devices without NCS messaging capabilities or embedded DOCSIS modems cannot access DQoS mechanisms
Solution Approach 1:
The patent introduces a Session Border Controller (SBC) as an intermediary device that bridges VoIP devices without NCS/DOCSIS capabilities and the DOCSIS network infrastructure. The SBC receives SIP messages from legacy VoIP devices, translates them into DOCSIS Dynamic Service Flow requests, and manages bandwidth allocation on behalf of these devices, enabling them to access DQoS mechanisms indirectly through the SBC mediator.
Solution Approach 2:
The system architecture is segmented into distinct functional components: the SBC handles SIP messaging and VoIP device management, while the DOCSIS cable modem handles network bandwidth management. This segmentation allows each component to operate independently with specialized protocols, enabling legacy VoIP devices to maintain their simplicity while still accessing advanced QoS features through the distributed architecture.
2Reliability
If multiple service flows are established for multiple VoIP devices, then each device can have dedicated bandwidth, but network complexity and resource management overhead increase
Solution Approach 1:
The patent merges the QoS management functions for multiple VoIP devices into a single DOCSIS service flow when possible. The SBC consolidates bandwidth requirements from multiple devices and establishes unified service flows to the CMTS, reducing the total number of service flows needed while still guaranteeing dedicated bandwidth for each device. This combining approach simplifies network resource management while maintaining individual QoS guarantees.
3Reliability
If DQoS resource reservation is implemented through network-based servers, then bandwidth allocation is reliable, but devices coupled to local area networks without external management servers lack access to DQoS
Solution Approach 1:
The SBC is configured with local DQoS policies and rules that enable it to autonomously make bandwidth allocation decisions without requiring external network-based servers. The SBC self-manages the translation of SIP messages into DOCSIS service flow requests and autonomously negotiates bandwidth allocation with the CMTS, providing DQoS capabilities to devices on local area networks independently of external server infrastructure.
Data Source
AI summary
A cable modem integrated session border controller operates as a point of demarcation between a local area network (LAN) and a DOCSIS network and, in response to receiving a Session Initiation Protocol (SIP) message, which includes Session Description Protocol (SDP), from a VoIP device coupled to the LAN, communicates with a Cable Modem Termination System (CMTS) to take advantage of DOCSIS Dynamic Quality of Service (DQoS). If required service flow attributes, as determined from the SDP of the SIP message, matches service flow attributes of an existing UGS service flow with a CMTS, a DOCSIS Dynamic Service Change (DSC) request is used to add an additional sub flow to the existing UGS service flow. If attributes fail to match attributes of all existing UGS service flows, a DOCSIS Dynamic Service Change (DSC) request is used to initiate an additional UGS service flow with the required service flow attributes.