Coordinated Media Access for Sensor Networks
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Solution Overview
Problem
Existing communications systems face challenges in achieving high data rates with low energy consumption, particularly in systems with multiple users and high traffic, where collisions and high energy consumption are prevalent, especially when nodes compete for access to a shared medium.
Innovation Solution
A communications system that employs a coordinated media access method with two transmission modes: a low-complexity first mode for initial reception and a higher-complexity second mode for higher data rates, dynamically selected based on message size, real-time requirements, and node ranking, allowing the control entity to manage access and optimize energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If competing methods (CSMA, ALOHA) are used for media access, then nodes can autonomously access the shared medium, but collisions occur resulting in lower data throughput and inability to guarantee real-time requirements
Solution Approach 1:
The patent introduces a coordinator entity as an intermediary that manages media access for battery-powered nodes. The coordinator receives access requests, grants permission selectively, and manages retransmissions, thereby preventing collisions while maintaining autonomous operation for end nodes. This resolves the contradiction by providing centralized coordination without requiring full autonomy at all nodes.
Solution Approach 2:
The patent segments the media access function into two parts: battery-powered nodes handle simple transmission initiation, while the coordinator handles collision prevention and retransmission management. This segmentation allows autonomous access at the node level while centralized control prevents collisions, resolving the throughput problem.
2Reliability
If coordinated methods (polling, scheduling) are used for media access, then collisions are avoided ensuring deterministic behavior, but system complexity and energy consumption increase
Solution Approach 1:
The patent applies different access mechanisms to different node types: battery-powered nodes use simple transmission initiation with coordinator-managed collision avoidance, while other nodes may use different methods. This local differentiation reduces overall system complexity and energy consumption by optimizing for the constraints of battery-powered devices without imposing unnecessary complexity on all nodes.
Solution Approach 2:
Battery-powered nodes autonomously initiate transmissions when they have data to send, eliminating the need for continuous polling or complex scheduling at the node level. The coordinator only intervenes when necessary for collision avoidance and retransmission management, reducing the energy burden on battery-powered nodes while maintaining deterministic behavior.
3Productivity
If high-complexity transmission methods are used to achieve high data rates, then throughput improves, but energy consumption increases particularly at receiving nodes
Solution Approach 1:
The patent implements selective activation of high-complexity transmission methods: only non-battery-powered receiving nodes continuously monitor for high-rate transmissions, while battery-powered nodes use simpler reception methods. This partial application of complex methods achieves high data rates where energy is available without imposing excessive energy consumption on battery-powered devices.
Data Source
AI summary
The present invention relates to a communications system (1) with at least one node (101, 102, 110), a control instance (10) and a shared communications medium (11). The at least one node is designed to receive messages that are or were transmitted in a first transmission mode. This first transmission mode has a lower data transmission rate and/or transmission complexity than a second transmission mode. The control instance (10) determines a first of the nodes in order to transmit data thereto in the second transmission mode or in order to release the shared communications medium (11) for the first node to transmit data in the second transmission mode. The control instance communicates this to the first node by means of a message (501, 502, 503, 504). This message is transmitted in the first transmission mode.