無線LAN環境における結合振動子の 同期現象に基づくメディアアクセス

1
! IEEE802.11
LAN
: CSMA/CA
! 
LAN
" 
– 
CSMA/CA
2
3
! 
! 
[0, CW(Contention Window)]
! 
AP
LAN
SP-MAC
# 
# 
! 
CW
" 
2
SP-MAC
1. 
2.  CSMA/CA
4
! 
5
! 
! 
Ex:
! 
,
dθ i
K
= ωi +
dt
N
! 
! 
N
∑ sin(θ
j
− θ i ) (i =1,2,… N)
j =1
Ex:
i
K
i
(
(
)
)
N
SP-MAC
6
N
! 
! 
SP-MAC
7
! CSMA/CA
Backoff = Random() × SlotTime
[0,CW]
1
! 1
dθi
K N
= ωi + ∑ sin(θ j − θi )
dt
N j =1
! 
! 
! 
! 
! RTS/CTS
(
IEEE802.11g
CW=15)
N
! SP-MAC
Backoff = ((| cosθi (t) | ×α)mod N) × SlotTime
N:
α = 100
cos
8
SP-MAC
1
9
cos
cos
1. 
2.  N
cosθ1(t)
cosθ3(t’)
AP
ωi,'
θi(0)
cosθ2(t’)
cosθ2(t)
cosθ1(t’)
cosθ3(t)
t
SP-MAC
N
1
3
2
t’
2
10
SP-MAC
3
3. 
11
4. 
'
AP
K,
AP
Δt
θi(t)
'
N=3
'
θ1(t), θ2(t), θ3(t)
dθi
K N
=
ω
+
∑ sin(θ j − θi )
i
'
dt
N j =1
1
3
2
1
N,'
ωi,'
3
'
θi(0),'
K,'
ID i,'
Δt
2
SP-MAC
4
12
5. 
AP
ID
SP-MAC
5
SP6MAC
θi(t)
AP
3 N=3
1
'
'
'
Backoff = ((| cosθ3 (t) | ×α)mod 3)
×SlotTime
'
Ack
'
'
• 
• 
'
Data
13
Collision
Data
Data
3
2
1
IFS
ACK
CSMA/CA
3
6. 
'
'
'
2
'
'
'
14
15
! SP-MAC CSMA/CA
! 
! 
UDP or TCP
! SP-MAC CSMA/CA
IEEE802.11g
(54Mbit/s)
100Mbps
10ms
– 
100Mbps
10ms
Receivers
Router
! 
Wired
Senders
AP
WLAN
1
1
16
SP-MAC
K
Δt
ns2 (ver.2.34)
1000 [byte]
AP
17
θi(0)
ω
250 [packet]
UDP(Rate:30Mbit/s),
TCP(CUBIC)
5
10 [ms]
(0, 1)
[0, 2]
[rad]
[rad/s]
60 [s]
5, 10, 20
10
UDP
UDP20
18
Original CSMA/CA
! SP-MAC
1.0
3.2
10.2
10
The number of collisions
55234.9
94796.6
135802.5
The number of collisions
The number of flows Original CSMA/CA SP-MAC
5
10
20
SP-MAC
3000
! 
19
2500
2000
1500
1000
500
8
6
4
2
0
0
0
20
40
Time [s]
60
0
20
40
Time [s]
60
UDP
! SP-MAC
40
35
30
25
20
15
10
5
0
Original CSMA/CA
10
The number of flows
20
CUBIC-TCP
Total throughput [Mbit/s]
UDP
The number of flows Original CSMA/CA SP-MAC
5
18446.9
0
10
56168.3
0
20
75248.9
1.4
5
40
35
30
25
20
15
10
5
0
21
UDP
! 
SP-MAC
UDP
TCP
Original CSMA/CA
SP-MAC
CUBIC-TCP
22
!  SP-MAC
CSMA/CA
! 
5
10
The number of flows
20
0.25
Standard deviation [Mbit/s]
Total throughput [Mbit/s]
!  SP-MAC
! SP-MAC
CUBIC-TCP
20
Original CSMA/CA
SP-MAC
0.2
0.15
0.1
0.05
0
5
10
The number of flows
20
23
CUBIC-TCP
24
! CSMA/CA
! SP-MAC
Total throughput [Mbit/s]
35
30
20
25
! 
SP-MAC
CSMA/CA
SP-MAC
! SP-MAC
– CSMA/CA
25
# 
# 
20
15
– CSMA/CA
# CSMA/CA
10
5
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Number of CSMA/CA terminals
(
22
(C) (
26
)
24500091, 26420367)
26
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