Shared Memory Communication Between Embedded Cable Modem and Set-Top Box
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Solution Overview
Problem
Existing communication protocols between embedded cable modems and set-top boxes are limited in complexity, cost, and reliability, particularly in supporting high-speed data transfers and out-of-band messaging over HFC infrastructure, as they require dedicated hardware and do not efficiently utilize hardware resources.
Innovation Solution
A digital communication system using shared memory between embedded cable modems and set-top boxes, implemented via packet transfer mechanisms without extra header overhead, utilizing Direct Memory Access (DMA) engines and System-On-Chip (SoC) processors with separate CPUs and a high-speed data bus protocol, establishing communication links mainly in layer 2 and partly in layer 1 of the OSI model to accelerate data transfer and reduce CPU load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated hardware is used for communication between eCM and eSTB, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the communication functionality between eCM and eSTB into the existing HFC infrastructure by utilizing the downstream and upstream paths already present in the cable network. Instead of adding dedicated communication hardware, the invention uses the existing DOCSIS-defined paths (downstream from CMTS to eSTB via eCM, and upstream from eSTB to CMTS via eCM) to carry OOB messages, thereby maintaining reliability while reducing hardware complexity and cost.
Solution Approach 2:
The patent makes the HFC infrastructure serve multiple functions by using the same downstream and upstream paths for both data communication and OOB messaging. The DOCSIS-defined paths are utilized not only for standard data traffic but also for carrying OOB messages between eCM and eSTB, eliminating the need for separate dedicated communication channels and reducing overall system complexity.
2Adaptability or versatility
If multiple unidirectional ports are used for different message types, then communication versatility is improved, but device complexity increases
Solution Approach 1:
The patent uses a universal communication path (the DOCSIS-defined downstream and upstream paths) to handle multiple types of messages including OOB messages, data traffic, and control information. Instead of implementing multiple specialized unidirectional ports, the invention makes the existing downstream and upstream paths multi-functional, allowing them to carry different types of traffic as needed, thereby maintaining versatility while reducing interface complexity.
Solution Approach 2:
Instead of creating multiple specialized ports for different message types, the patent inverts the approach by using a single bidirectional communication path (downstream and upstream) to handle all message types. This inversion simplifies the interface structure while maintaining the ability to communicate various types of information by utilizing the flexibility of the DOCSIS-defined paths.
3Reliability
If TCP or UDP with USB or Ethernet is used for physical transmission, then communication reliability is improved, but ease of manufacture decreases
Solution Approach 1:
The patent leverages the existing HFC infrastructure and DOCSIS protocol stack that are already widely deployed in cable networks. By using the established downstream and upstream paths defined in DOCSIS, the invention avoids the need to manufacture and integrate additional physical transmission hardware such as USB or Ethernet interfaces, thereby improving ease of manufacture while maintaining communication reliability through the proven HFC infrastructure.
Data Source
AI summary
The present disclosure discloses a digital communication between the embedded cable modem (eCM) and embedded set-top box (eSTB) via a shared memory. The communication is carried out by packet transfer mechanism as per the protocol without adding any extra header overhead. The communication link is established between the eSTB and eCM mainly in layer 2 and partly in layer 1 according to an implementation of the OSI model. Further, eSTB is used as an eSAFE device coupled to eCM where the eCM and eSTB are considered to be placed on two SoCs with a separate CPU to each SoC (System-On-Chip) with a shared memory (via high speed data bus protocol). DMA (Direct Memory Access) engines are used to accelerate data transfer and to reduce load. DMA of only eCM, SoC is used to minimize hardware resources.