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Wireless multi-hop self-organizing network time synchronization system base on parallel transmission

A time synchronization system and wireless multi-hop technology, applied in synchronization devices, wireless communication, network topology, etc., can solve the problems of long time synchronization convergence time, large time delay, and data transmission packet conflicts in the entire network

Active Publication Date: 2014-09-03
浙江孕橙医疗科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In a multi-hop self-organizing network, for the time synchronization protocol, the main problems brought by the CSMA / CA protocol are: 1) the time delay is large, resulting in a long time for the time synchronization convergence of the entire network; 2) the control frame occupies a large amount of network bandwidth; 3) Packet loss due to data transmission packet collision, which affects synchronization performance
[0032] To sum up, the single-hop time synchronization technology is relatively mature, but the multi-hop time synchronization, especially the time synchronization protocol applied to the multi-hop ad hoc network, uses the CSMA / CA MAC layer access mechanism, resulting in large time delay and data Packet conflicts, relay node clock instability have a great impact on subsequent node synchronization errors, etc., the present invention proposes a parallel transmission technology based on plastic interference to achieve fast, low power consumption, and time synchronization system applicable to dynamic topology

Method used

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  • Wireless multi-hop self-organizing network time synchronization system base on parallel transmission
  • Wireless multi-hop self-organizing network time synchronization system base on parallel transmission
  • Wireless multi-hop self-organizing network time synchronization system base on parallel transmission

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Embodiment 1

[0093] see Figure 7 , the embodiment of the present invention provides a time synchronization system based on parallel transmission applied to a wireless multi-hop ad hoc network. The network node adopts the IEEE 802.15.4 communication standard. Specifically, the network node can adopt the widely used TMOTE SKY node, which includes four parts: sensor module, computing module, wireless communication module and power supply module. The sensor module has nothing to do with this time synchronization system and can be ignored. The calculation module adopts TI's MSP430F149 low-power single-chip microcomputer, and an external 4MHz crystal oscillator O 1 . The wireless communication module adopts the CC2420 module of TI company, and the external 16MHz crystal oscillator O 2 . The computing module and wireless communication module can also be integrated in a unified chip, using a single crystal oscillator, such as TI's new low-power microcontroller CC430, thereby reducing the nod...

Embodiment 2

[0109] In this embodiment, the nodes in the network are in a static or quasi-static state, and the network topology remains basically unchanged, such as Image 6 shown.

[0110] This embodiment is mainly applied to occasions where the nodes will not move after being fixedly deployed, such as atmospheric environment monitoring, agricultural and forestry monitoring, and the like.

[0111] On the basis of ensuring coverage, by reducing the number of nodes in parallel transmission, the probability of beacon packet collision is reduced and energy consumption is reduced.

[0112] Given a network topology map, first use the BFS algorithm to traverse the network topology map, calculate the shortest number of hops from each node to the sink node, and classify the points with the same shortest number of hops as a set at the same level, such as Φ 1 , Φ 2 ,…,Φ M . set Φ i Represents the set of nodes that are i hops away from the sink node.

[0113] from Φ 1 Start selecting the mini...

Embodiment 3

[0124] Embodiment 1 and Embodiment 2 also have a variant, that is, the node adopts another linear recursive method to estimate the clock frequency deviation and the variance of the clock frequency deviation. At this time, the node may not perform step S51, that is, the phase deviation correction is not performed, and the rest Same as Embodiment 1 or Embodiment 2.

[0125] When the i-th beacon packet is received, the measurement time of the local clock is c i , then the estimated value p of the clock phase deviation after linear recursion is used 校 , the clock frequency deviation estimate f 校 , the variance of the clock frequency deviation estimate var(f 校 )for:

[0126] c ‾ = 1 w Σ i = 1 w c i - - - ( 5 ...

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Abstract

The invention relates to a wireless multi-hop self-organizing network time synchronization system base on a parallel transmission mechanism; the network comprises a plurality of nodes, wherein one node (called Sink node) is externally connected with a public reference clock source; full network time synchronization can be realized through the following steps: the sink node regularly sends a beacon packet containing time synchronization information; the beacon packet is broadcasted in the full network in a parallel broadcasting mode through plasticity interference; the sink node measures starting sending time of the beacon packet in a time synchronization period, and inserts the sending time into the beacon packet; a calculation module updates forwarding times in the beacon packet and immediately forwards the beacon packet after the node receiving the beacon packet; after the node receives the beacon packet, the time synchronization information in the beacon packet can be used to carry out local clock phase deviation correction and frequency deviation correction, and phase deviation and frequency deviation correction values can be used for completing time synchronization.

Description

technical field [0001] The invention relates to the field of wireless multi-hop self-organizing networks, in particular to a fast, low power consumption time synchronization method and system based on parallel transmission. Background technique [0002] A wireless ad hoc network is an autonomous system. The entire network has no fixed infrastructure, no strict control center, and all nodes have equal status. Nodes can join and leave the network at any time, and the network topology can dynamically adapt to changes in the network environment. [0003] A wireless multi-hop network means that due to the limited transmission power and coverage of the nodes, the nodes in the network that are far away need to communicate by means of forwarding by other relay nodes. A wireless ad hoc network is generally a multi-hop network, also known as a wireless multi-hop ad hoc network. It is worth noting that, different from the multi-hop transmission in the Internet, the multi-hop routing ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04W56/00H04W84/18
Inventor 不公告发明人
Owner 浙江孕橙医疗科技有限公司
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