CSMA/CD Token Access for TDMA Collision Management
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Solution Overview
Problem
In TDMA radio communication systems, collisions occur when multiple terminals attempt to transmit on a shared broadcast channel simultaneously, leading to data reception failures due to the inability to detect collisions and the limited availability of the medium within specific time intervals.
Innovation Solution
A method based on the CSMA/CD protocol, where terminals listen to the medium, issue a token, and receive responses to determine if a collision has occurred, adjusting their transmission accordingly, with the use of pure sinusoidal tokens and district-based message transmission to facilitate efficient access and reduce collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple terminals transmit simultaneously on a shared broadcast channel, then communication efficiency is improved, but collisions occur causing data reception failures
Solution Approach 1:
The patent implements a preliminary action by requiring terminals to send a token before transmitting data. This token serves as a preliminary request for permission to use the shared medium. The terminal waits for an acknowledgment from the base station before proceeding with data transmission, thus preventing simultaneous transmissions and collisions while maintaining communication efficiency.
2Reliability
If terminals wait for medium availability before transmitting, then collisions are reduced, but transmission delay increases
Solution Approach 1:
The patent implements feedback through the acknowledgment mechanism. When a terminal sends a token, it waits for an acknowledgment from the base station. This feedback loop provides real-time information about medium availability, allowing terminals to transmit immediately upon receiving acknowledgment without unnecessary waiting periods, thus reducing transmission delay while avoiding collisions.
3Productivity
If the broadcast channel is shared among all terminals, then resource utilization is improved, but collision detection capability is lost
Solution Approach 1:
The patent introduces an intermediary mechanism where the base station acts as a central coordinator. Instead of terminals attempting to detect collisions directly among themselves, the base station receives tokens from multiple terminals and provides centralized arbitration by sending acknowledgments. This intermediary approach maintains high resource utilization through the shared broadcast channel while eliminating the need for complex collision detection capabilities at terminal level.
Data Source
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AI summary
The present invention relates to the field of methods for managing access to a communication medium shared by a plurality of radio communication devices. The invention describes a method of accessing a radio communication medium shared between a plurality of communication terminals. This method is based on a variant of the CSMA/CD access protocol. This method is based on monitoring of the medium and the emission of a token to request permission to emit. The terminals that receive this token then emit an acknowledgement intended to signal that the medium can be used, or a collision message if they receive a plurality of tokens simultaneously. In the latter case, the emitter retries its attempt to use the medium later on.