Synchronous Sensor Network Beacon Collision Reduction
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Solution Overview
Problem
Conventional synchronous ubiquitous sensor networks experience significant delays in beacon packet transmission due to increased number of nodes and hops, leading to inaccurate time synchronization and unreliable data transmission, especially in emergency situations.
Innovation Solution
The method involves outputting a beacon frame to control active and inactive periods of sensor nodes, using a single or multiple channels, and employing a carrier sense multiple access/collision avoidance (CSMA/CA) algorithm to prevent collisions, while maintaining a higher output power for beacon frames and reduced power for data transmission, allowing for efficient emergency data transmission and reduced initialization time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the number of nodes and hops is increased to expand network coverage, then the sensor network coverage is improved, but the beacon packet transmission delay is greatly increased
Solution Approach 1:
The network is divided into multiple sensor fields, each managed by a coordinator node that independently handles beacon packet transmission and node synchronization within its field, reducing the propagation delay across the entire network
Solution Approach 2:
Coordinator nodes act as intermediary devices between the PAN coordinator and end nodes, receiving and forwarding beacon packets to reduce the number of hops and transmission delay for nodes in extended sensor fields
2Reliability
If beacon packets are routed through multiple coordinators to reach end nodes, then network connectivity is maintained, but serious delay occurs in synchronization
Solution Approach 1:
The network is divided into multiple sensor fields, each managed by a coordinator node that independently handles beacon packet transmission and node synchronization within its field, reducing the propagation delay across the entire network
Solution Approach 2:
Coordinator nodes pre-establish routing paths and synchronize their clocks with the PAN coordinator before transmitting beacon packets to end nodes, ensuring minimal delay in the synchronization process
3Reliability
If emergency data is transmitted through routing nodes, then data reaches the PAN coordinator, but great delay occurs due to synchronization requirements
Solution Approach 1:
Emergency data transmission is extracted from the normal synchronized communication protocol, allowing end nodes to transmit urgent information immediately through routing nodes without waiting for the next beacon packet cycle or active period
Solution Approach 2:
The system allows emergency data packets to skip the normal synchronization waiting period and be transmitted immediately through the network, rushing through the routing nodes to reach the PAN coordinator without the usual delay
Data Source
AI summary
A method and apparatus using a synchronous sensor network medium access control (MAC) protocol, such as a ZigBee or IEEE 802.15.4 low-rate wireless personal area network (WPAN), is disclosed. A method and apparatus for constructing a ubiquitous sensor network (USN) of which a life is increased by using power beacons and reducing the number of unnecessary control packets (beacon packets), thereby reducing an initialization time between nodes and preventing beacon collision, is also disclosed. A beacon packet channel having a large output power and a data channel of which a transmission range is restricted by reducing an output power to be less than that of the beacon packet channel, may be simultaneously used.