Cable Modem Upstream Bandwidth Allocation with Predictive Grants
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Solution Overview
Problem
Conventional cable modem communication networks face issues of latency in upstream bandwidth allocation due to one-to-one request and response interactions, and inefficiencies in proactive grant services when service flows stop using allocated bandwidth.
Innovation Solution
A new technique that combines best-effort and proactive grant services by predicting bandwidth needs and allocating upstream bandwidth based on service flow requests, guaranteed requirements, and proactive grants, ensuring efficient and reduced latency allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional best-effort technique is used for upstream bandwidth allocation, then bandwidth can be allocated based on actual requests, but latency increases due to one-to-one request-response interactions
Solution Approach 1:
The CMTS proactively allocates upstream bandwidth to service flows before actual data transmission is needed. The system predicts bandwidth requirements and pre-assigns timeslots, eliminating the waiting time associated with request-response cycles. This preliminary action directly reduces latency while maintaining efficient bandwidth utilization through predictive algorithms.
2Productivity
If conventional proactive grant services are used for upstream bandwidth allocation, then latency is reduced through proactive allocation, but bandwidth allocation efficiency decreases when service flows stop using allocated bandwidth
Solution Approach 1:
The system continuously monitors actual bandwidth usage of service flows and uses this feedback to adjust proactive bandwidth allocations. When service flows stop using allocated bandwidth, the CMTS detects this through feedback mechanisms and reassigns those timeslots to other active service flows. This closed-loop feedback system eliminates wasted bandwidth while maintaining the low-latency benefits of proactive allocation.
Solution Approach 2:
The proactive bandwidth allocation is made dynamic rather than static. The CMTS continuously adapts bandwidth assignments based on real-time service flow activity, increasing allocation when needed and decreasing it when service flows become inactive. This dynamic adjustment ensures optimal bandwidth utilization without the waste associated with static proactive grants.
3Ease of operation
If conventional proactive grant services are used, then fewer requests need to be transmitted by modems, but inefficient bandwidth allocation occurs when service flows stop using allocated bandwidth
Solution Approach 1:
The system maintains the simplified operation of proactive grants (fewer modem requests) while adding feedback mechanisms that allow the CMTS to monitor actual bandwidth usage. This feedback enables the CMTS to detect when service flows become inactive and adjust allocations accordingly, resolving the inefficiency without increasing the number of requests modems must transmit.
Data Source
AI summary
In a cable modem network, upstream bandwidth is allocated to service flows by receiving requests from modems, wherein each request identifies an amount of requested bandwidth for a corresponding requesting service flow; determining how much best-effort bandwidth to allocate for each requesting service flow; determining how much remaining bandwidth is available after taking into account all of the best-effort bandwidth for the requesting service flows; determining how much of the remaining bandwidth to allocate as proactive grant service (PGS) upstream bandwidth to PGS service flows; determining, for each requesting service flow, a summed bandwidth as a sum of any corresponding best-effort bandwidth and any corresponding PGS bandwidth; determining, for each requesting service flow, an amount of allocated bandwidth as a minimum of the summed bandwidth and a maximum allowable bandwidth; and transmitting grants to the modems identifying the amounts of allocated upstream bandwidth for the corresponding service flows.