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self organisation & syncronization
Typology: Slides
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Wireless systems
Fireflies
Synchronization
Self-Organization
c
Raises requirements:• Adaptability• Distributed operation• Autoconfiguration
Trend Toward Self-Organization in Computing & Communications
(a
d hoc networks
)
Increased dynamics and
complexity
c
Point-to-point synchronization:Network synchronization:
Master-slave synchronization
(monarchy)
Mutual synchronization
(base democracy)
Mix of master-slave and mutual synchronization
(oligarchy)
frequency correction bursts
Adjustment of the sending and receiving frequencies of a MS to thefrequencies of the BTS
(frequency correction, synchronization bursts
repeating transmit frame
The BTS sends signals on the
Broadcast
Control Channel (BCCH)
to enable the
MS to synchronize itself to the BTS.
BTS
MS
Step #2:Compute average: R. Gusella and S. Zatti: The accuracy of the clock synchronization achieved by TEMPO in Berkeley UNIX 4.3BSD,
IEEE Trans.
on Software Engineering
, 15 (7): 847–853, 1989. © 1989 IEEE. Figure used with kind permission from the IEEE IPR Office.
Step #3:Correct clocks: R. Gusella and S. Zatti: The accuracy of the clock synchronization achieved by TEMPO in Berkeley UNIX 4.3BSD,
IEEE Trans.
on Software Engineering
, 15 (7): 847–853, 1989. © 1989 IEEE. Figure used with kind permission from the IEEE IPR Office.
Master-slave synchronization
(monarchy)
Mix of master-slave and mutual synchronization
(oligarchy)
Mutual synchronization
(base democracy)
(P. Laurent,
Science
BBC : “Trials of Life”, Video , 1917)
A video is shown here.
Early hypotheses of the mechanism • Environment (e.g. wind, thunder) triggers the synchronization• Some “leader” firefly controls the synchronized flashing Experimental work (1960s to 80s) • Firefly in a dark room flashes with quite constant frequency• Exposed to generated light flashes, it responds to these stimuli
A: no influenceB: delay in flashingC: earlier 2nd next flash
J. Buck
et al.
: Control of Flashing in Fireflies V
. Journal of Comparative Physiology A
, 144:630–633, 1981.
Values in ms
Phase
Φ
( t
)
0
T
2
T
t
FIRE
FIRE
FIRE
Threshold
2 π
LISTEN
Internal clock
