Upload
dagmar
View
48
Download
0
Tags:
Embed Size (px)
DESCRIPTION
An Improved CDMA-Based MAC Protocol for Underwater Acoustic Wireless Sensor Networks. Guangyu Fan, Huifang Chen, Lei Xie , Kuang Wang. IEEE WICOM 2011. Introduction. The world's oceans cover over 70 % of its surface Underwater Wireless Sensor Networks (UWSNs). Introduction. - PowerPoint PPT Presentation
Citation preview
An Improved CDMA-Based MAC Protocol for Underwater Acoustic
Wireless Sensor Networks
Guangyu Fan, Huifang Chen, Lei Xie, Kuang Wang
IEEE WICOM 2011
The world's oceans cover over 70 % of its surface Underwater Wireless Sensor Networks (UWSNs)
Introduction
Underwater sensor network technology can be applied in many fields Environment monitoring Geographic data collection Offshore exploration Assisted navigation Disaster prevention Tactical surveillance
Introduction
Transmission rate WSN: 3 x 108 m/s UWSN: 1500 m/s
Propagation delay
Introduction
A
B
Propagation delay
B A
Problem Long propagation delay
Introduction
RTS
RTS
RTS
CTS
CTS
DATA
DATA
RTS
CTS
A
B
C
CDMA-based protocols Transmitter-oriented code assignment (TOCA) Receiver-oriented code assignment (ROCA) Path-oriented code assignment (POCA)
Introduction
Slotted FAMA
Related works
RTS
RTS
RTS
CTS
CTS
DATA
DATA
RTS
CTS DEFERS TRANSMISSIONS
A
B
C
MaximumPropagation Delay+CTS
Waste time !
RIPT
Related works
Disadvantage
Related works
Collision
In the paper, POCA-CDMA-MAC is proposed for UWASNs. It utilizes a round-robin method and CDMA technology to reduce
collisions of packets.
Goal
Assumption Sink can receive packets from multiple neighbors at the same time Routes will be built All sensor nodes are equipped with a half-duplex, omni-directional
transceiver
Network environment
POCA-CDMA-MAC
AP1
BP1
AP2
BP2
CP2 BP3BP4
AP5
BP5
CP5
AP6
BP6
CP6
CP7
Surface station
Sink
POCA-CDMA-MAC
AP1
BP1
AP2
BP2
CP2 BP3BP4
AP5
BP5
CP5
AP6
BP6
CP6
CP7
Sink
(s1,s2,s3,s4,s5,s6,s7)
POCA-CDMA-MAC
AP1
BP1
AP2
BP2
CP2 BP3BP4
AP5
BP5
CP5
AP6
BP6
CP6
CP7
Sink
(s2,s3,s4,s5,s6,s7)s1
POCA-CDMA-MAC
AP1
BP1
AP2
BP2
CP2 BP3BP4
AP5
BP5
CP5
AP6
BP6
CP6
CP7
Sink
(s2,s3,s4,s5,s6,s7)
s1
POCA-CDMA-MAC
AP1
BP1
AP2
BP2
CP2 BP3BP4
AP5
BP5
CP5
AP6
BP6
CP6
CP7
Sink
(s5,s6,s7)
s1
s2s3
s4
POCA-CDMA-MAC
AP1
BP1
AP2
BP2
CP2 BP3BP4
AP5
BP5
CP5
AP6
BP6
CP6
CP7
Sink
(s5,s6,s7)
s1
s2s3 s4
POCA-CDMA-MAC
AP1
BP1
AP2
BP2
CP2 BP3BP4
AP5
BP5
CP5
AP6
BP6
CP6
CP7
Sinks1
s2s3 s4
s5
s6
s7
POCA-CDMA-MACAP2
BP2
CP2
Sink
CP2
BP2
AP2
Sink
POCA-CDMA-MACAP2
BP2
CP2
Sink
CP2
BP2
AP2
Sink
POCA-CDMA-MACAP2
BP2
CP2
Sink
CP2
BP2
AP2
Sink
POCA-CDMA-MACAP2
BP2
CP2
Sink
CP2
BP2
AP2
Sink
Problem
POCA-CDMA-MACAP2
BP2
CP2
Sink
CP2
BP2
AP2
Sink
Solution
POCA-CDMA-MACAP2
BP2
CP2
Sink
CP2
BP2
AP2
Sink
Passing token
Simulation
Parameter Value
Transmission range 7.5 km
Data packet 500 bytes
Static Nodes 8
Control packet 12.5 bytes
Simulation
Simulation
Simulation
In the proposed MAC protocol prevent collision of packets and the length of the spreading sequence codes is shortened by using round-robin method CDMA technology
Each node encodes its packets with a spreading sequence, so the sink can receive packets from multiple neighbors at the same time.
Conclusion