Media Arbitration Using Static and Dynamic Time Slots

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Solution Overview

Problem

Current communication protocols for multi-node distributed systems in automotive applications, such as FlexRay, fail to meet all Media Access Scheme (MAS) requirements, particularly in handling fault-free conditions, oscillator drifts, and collision avoidance.

Innovation Solution

A system and method for media arbitration that utilizes a combination of static and dynamic communication slots, with alternating matching and mismatching time slots, and a synchronized time base to ensure periodic recurrence and fault tolerance, addressing the limitations of existing protocols.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a TDMA scheme with FTDMA arrangement is used for FlexRay protocol, then static and dynamic media arbitration can be implemented, but collision avoidance and oscillator drift compensation cannot be simultaneously satisfied

Engineering Contradiction:

Improvemedia arbitration capabilityVSAvoidcollision avoidance and drift compensation

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The communication cycle is segmented into multiple communication slots, each further divided into timeslots. This hierarchical segmentation allows static slots for predetermined communications and dynamic slots for run-time determined arbitration, resolving the contradiction between adaptability and reliability by handling different traffic types separately

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The arbitration scheme uses periodically recurring communication cycles with synchronized time bases. Each cycle contains predetermined communication slots followed by dynamic slots, creating a periodic structure that ensures collision avoidance through synchronization while maintaining adaptability for dynamic communications

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If synchronized time base is used for media arbitration, then communication jitter is well defined, but handling large oscillator drifts becomes difficult

Engineering Contradiction:

Improvecommunication jitter definitionVSAvoidoscillator drift compensation

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The system dynamically adjusts the interpretation of time slot boundaries based on synchronization status. During synchronization, strict time base alignment provides precise jitter definition. During drift compensation, the system dynamically adapts by allowing flexible slot boundary interpretation, resolving the contradiction between precision and adaptability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The arbitration mechanism changes parameters such as slot boundary timing and synchronization reference points based on detected oscillator drift. This allows the system to maintain precise jitter measurement during normal operation while adapting to large drifts when they occur

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If predetermined communication slots are used for static communication, then communication pattern is stable, but dynamic communication flexibility is reduced

Engineering Contradiction:

Improvecommunication pattern stabilityVSAvoiddynamic communication allocation

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The communication cycle is divided into distinct predetermined slots for stable communications and dynamic slots for flexible allocation. This segmentation maintains stability for time-critical communications while providing adaptability for variable traffic, resolving the contradiction between stability and versatility

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8085700B2System node and method for providing media arbitration

Publication Date: 2011.12.27 NXP USA INC

AI summary

A multi-node communications system is provided with communications protocol using both static (11, 12, 13, 18) (pre-determined) and dynamic (51, 52, 53 . . . ) (run-time determined) consecutive communication slots is used. The system has a number of distributed communication nodes, each node being arranged for communicating frames of data with the other nodes during both the static (11, 12, 13 . . . ) and the dynamic (51, 52, 53 . . . ) communication slots. Each node includes a synchronized time base 5 made up of consecutive timeslots (11, 12, 13 . . . , 51, 52, 53 . . . ). The timebase 5 has substantially the same error tolerance in each node. For static communication (10), a predetermined number of timeslots (20) are utilized for each static communication slot. For dynamic communication a dynamically allocated number of timeslots (60) are utilized for each dynamic communication slot. In this way both static and dynamic media arbitration is provided within a periodically recurring communication pattern. Communication jitter is well defined and dealt with, and large oscillator drifts are compensated for.