Hybrid Contention Polling MAC Mechanism for Coaxial Networks
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Solution Overview
Problem
Conventional MAC layer mechanisms, such as DCF and PCF, do not perform effectively in bidirectional data transmission over coaxial cable networks like ADoC systems due to differences in signal transmission environments and network architectures, leading to inefficiencies in controlling data transmission between access points and multiple stations.
Innovation Solution
An access point device and communication units exchange media access request messages with assigned durations, allowing for a contention mode followed by a polling period to manage media access, reducing contention through Clear To Send (CTS) messages and Request to Transmit (RTT) frames, ensuring controlled access during the polling period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional MAC layer mechanisms (DCF or PCF) are used in ADoC systems, then the system can provide bidirectional data transmission over coaxial cable, but the transmission efficiency and media access control performance deteriorate due to mismatch with the cable transmission environment
Solution Approach 1:
The patent modifies the MAC layer parameters and mechanisms to adapt to coaxial cable transmission characteristics. Specifically, it changes the media access control parameters such as contention period duration, polling period structure, and message timing parameters to match the signal propagation and transmission characteristics of coaxial cable networks, thereby resolving the mismatch between conventional wireless-oriented MAC mechanisms and wire-line cable transmission environment
Solution Approach 2:
The patent introduces dynamic adjustment of media access parameters based on network conditions. The system dynamically configures contention period lengths, polling intervals, and station allocation durations according to real-time traffic load and network status, enabling the MAC layer to adapt flexibly to varying transmission conditions in the coaxial cable network
2Productivity
If multiple communication units transmit data simultaneously in contention mode, then the media utilization increases, but transmission conflicts and data loss increase
Solution Approach 1:
The patent implements periodic alternation between contention mode and polling mode. During contention period, multiple stations can attempt transmission simultaneously to maximize media utilization. During polling period, the access point systematically polls each station to ensure conflict-free transmission. This periodic switching between two modes balances media utilization and transmission reliability
Solution Approach 2:
The patent segments the media access process into distinct phases: contention period for simultaneous access attempts and polling period for controlled sequential access. This segmentation allows the system to exploit parallelism during contention while ensuring reliability during polling, effectively separating the conflicting requirements of high utilization and low conflict rate
3Reliability
If the access point polls each communication unit individually, then transmission conflicts are eliminated, but the access delay and latency increase
Solution Approach 1:
The patent implements preliminary action by having stations send media access request messages during the contention period before the polling period begins. Stations indicate their transmission needs in advance, allowing the access point to prepare the polling sequence beforehand. This preliminary declaration of intent reduces the actual waiting time during polling compared to pure demand-based sequential access
Data Source
AI summary
The present invention provides an access point device, a communication unit and a method for access to a communication media in a communication network. The access point comprises a communication interface for exchanging data with a plurality of communication units in the communication network via the communication media; and a processor for receiving a media access request message in a contention mode from at least one communication unit of the plurality of communication units via the communication interface; and polling the at least one communication unit by assigning a media access duration to each of the at least one communication unit according to a corresponding duration information for media access in the received media access request message.