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M1gp2012
1. Design and Evaluation of a
Versatile and Efficient
Receiver-Initiated Link Layer
for Low-Power Wireless
P. Dutta et.al ACM SenSys 10 November 3-5 2010
2012年5月12日
電気系森川研究室
井上雅典1
9. Sender-‐Ini+atedとReceiver-‐Ini+ated
• Sender-‐Ini+ated（SenderがRequestを送信）
R
Data
Sender
L
L
L
Data
L
Receiver
L
:
Listen
Data
:
Data
Transmit
R
:
Request
9
10. Sender-‐Ini+atedの例
• Low-‐Power
Listening(LPL)
Long-‐
Data
Sender
Preamble
L
L
L
Data
L
Receiver
:
Long-‐Preamble
L
:
Listen
Data
:
Data
Transmit
○ Listen時間を非常に少なくできる
10
11. Sender-‐Ini+atedとReceiver-‐Ini+ated
• Receiver-‐Ini+ated（ReceiverがRequestを送信）
L
Data
Sender
R
R
Data
Receiver
L
:
Listen
Data
:
Data
Transmit
R
:
Request
11
12. Receiver-‐Ini+atedの例
• RI-‐MAC
L
Data
L
Sender
B
L
B
Data
B
B
L
Receiver
R
:
Beacon
L
:
Listen
Data
:
Data
Transmit
○ Beaconを送ってすぐDataが返ってくる⇒Duty比削減
× Listen時間がLPLより長くなってしまう
12
19. A-‐MACは干渉に強い！
• LPL
ムダ
• A-‐MAC
Noise
Receiver
L
Listening
OTHER
衝突か？？
ムダなし
P
L
OTHER
Noise
Receiver
• RI-‐MAC
AUTO-‐ACKが
来ていない！
OTHER
Noise
ムダ
B
Listening
Receiver
衝突か？？
19
30. RI-‐MACの衝突への対応
Beacon containing a larger backoff window
B DATA B DATA B
S1 Collision Backoff
B B DATA B DATA B
R
B DATA B DATA B DATA B
S2
Figure 6: DATA frame transmission from contending senders
in RI-MAC. For the first beacon, the receiver R requests
senders (here, S1 and S2 ) to start transmitting DATA imme-
30
32. MACアドレスの変更
Auto-‐Ackを返すためにSenderのMACアドレスを変更する
送り先のReceiverの
MacAddress+8000をセット
56789:999; 4.4 B
6<289:999!
6ΒΧ89:;≅
Broad
=>289:∀99;
#∃%&∋2 3,45&1 ! ∀ 6 !
range of
)0&1%&./ discover
(MAC=0X0001)
pend on
design of
nications
#∃%&∋( disables
! ∀ 6 ! 3
)∗&+&,−&./ 56789:∀99; 56789:∀99; hardware
(MAC=0X0002)
6<289:999; 6<289:999; auto-ack
>2?89:99;≅ they can
Α<=89:999!
When
Figure 3. Example of an A-MAC unicast communication it 32
th
sets
showing dynamic address changes and other frame fields. address,
33. Broadcast
Communica+onsを用いた
非同期ネットワークのwakeup
Node 1 Listen P A Listen
Node 2 P A Listen P A Listen P A Listen P A
DST=0xFFFF
SRC=0x0002
Node 3 P A Listen P A
DST=0xFFFF
SRC=0x0003
Node 4 P A Listen P A
DST=0xFFFF
SRC=0x0004
Node 5 P A
DST=0xFFFF
SRC=0x0005
Backcast
F
Figure 4. Asynchronous network wakeup with A-MAC. 33
te
34. Path
Delay/Power
Difference評価
• Ackの遅延/信号強度差による復号を評価した
500nsまでなら建設的 3dB以上の差があれば
実験環境
干渉となる
復号出来る
USB RF 1
Initiator 1
2
0.9 0.9
0.8 0.8
Packet Reception Rate
Packet Reception Rate
1 3
Circulator (2) 0.7 0.7
0.6 0.6
Channel 2
Channel 1
0.5 0.5
0.4 0.4
Wireless Channel Emulator
0.3 0.3
3 1 0.2
0.2
2 0.1 0.1
Responder 0 0
500 550 600 650 700 750 800 0.5 1 1.5 2 2.5 3 3.5
Faraday Cage Path Delay Difference (ns) Path Power Difference (dB)
(a) Experimental Setup (b) Intersymbol Interference (c) Power Capture
Figure 6. Figure (a) shows the experimental setup. Figure (b) shows the onset of destructive inter-symbol interference.
Packet reception rate falls sharply as the delay difference in two paths exceeds 0.5 µs. Figure (c) shows the effect of
power capture. When two frames collide, the first frame to arrive will be decoded correctly if its receive power is 3 dB
higher than the second frame. 34
35. 0.8 0.8
Packet Reception Rate
Packet Reception Rate
1 3
Circulator (2) 0.7 0.7
0.6 0.6
Channel 2
Channel 1
多数Ack同士のcollision
0.5 0.5
0.4 0.4
Wireless Channel Emulator
0.3 0.3
3 1 0.2
0.2
2 0.1 0.1
Responder 0 0
500 550 600 650 700 750 800 0.5 1 1.5 2 2.5 3 3.5
Faraday Cage Path Delay Difference (ns) Path Power Difference (dB)
(a) Experimental Setup (b) Intersymbol Interference (c) Power Capture
Figure 6. Figure (a) shows the experimental setup. Figure (b) shows the onset of destructive inter-symbol interference.
• 通常の室内環境において1個〜94個のAckをcollisionさせた場合の評価
Packet reception rate falls sharply as the delay difference in two paths exceeds 0.5 µs. Figure (c) shows the effect of
power capture. When two frames collide, the first frame to arrive will be decoded correctly if its receive power is 3 dB
higher than the second frame.
HACK
● ●
106 ●
●
●
102 ●
●
98 ● ●
●
94 ● ● ● ●
LQI
● ● ●
● ● ● ● ● ● ● ● ● ●
● ● ● ● ● ● ● ● ● ●
90 ● ● ●
●
● ●
●
●
●
● ● ●
●
●
●
● ●
●
● ●
●
●
●
●
●
●
●
● ●
● ● ● ● ● ● ● ● ● ● ● ● ● ●
86 ●
●
●
●
●
●
●
● ●
●
●
● ● ●
●
●
●
● ●
82
78
●
74
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82 85 88 91 94
Figure 7. The effect on LQI as the number of concurrent ACKs increases from 0 to 94 in a typical indoor deployment
setting. The median value of LQI falls quickly for the first six nodes and then falls slowly. Beyond approximately 30
nodes, the LQI values stabilize at approximately 100. The data suggest that even in the presence of a large number of
ACK collisions, the receiver can successfully decode the ACK frame. Note the y-axis ranges from 74 to 106.
35
36. Curre
Curre
5 5
Probe/Receive/Transmit/Idle
0
0 5 10 15
0
0 20 40 60 8
Time (ms) Time (ms)
• 各状態における電流/消費電力
（Telos
BProbe
(a)
mote）
(b) Receive (Len=127 by
1000
Primitive Cost (µJ)
Average current (uA)
800
Probe 253
TX only 1578 600
RX only 2670 400
CCA Check 194
200
20 20 20 20 0
0 0.5 1 1.5
15 15 15 15 Probe period (s)
Current (mA)
Current (mA)
Current (mA)
Current (mA)
10 10
(e) Primitive energy costs 10 10
(f) Probe
5 5 5 5
0 Figure 8. Link Power Model. Figures (a)-(c) show th
0 0 0
0 5 10
Time (ms)
15
asynchronous link primitives. Figure (d) shows the cu
0 20 40 60
Time (ms)
80 590 600 610 620
Time (ms)
630 0 200 400
Time (ms)
600 800
(a) Probe (b) Receive (Len=127 bytes)
1000
(c) Transmit (Len=127 bytes)
(e) shows the cost of each link primitive. Figures (f), (d) Idle (500 ms wait)
4 4
10 10
Primitive Cost (µJ) transmitting, respectively, as a function of the probe p Asynchronous
ent (uA)
ent (uA)
ent (uA)
800 36
Scheduled
Probe 253
37. 0 0
10 15 0 1000 2000 3000 0 50 100 150
me (ms) Time (ms) Time (ms)
mple detail
LPL -‐非干渉時/干渉時の評価-‐
(c) LPL sampling (w/ interfer-
ence)
(d) LPL overhearing detail
es leave receivers susceptible to noisy wireless environments, such as those
nd (b) show the macroscopic and microscopic behavior of the TinyOS 2.1
• LPLを外部から干渉時しない環境と、802.11のアクセス
r: the receiver immediately returns to sleep. Figures (c) and (d) show the
e a file transfer is in progress using a nearby 802.11 access point. Of the
ポイント付近(干渉あり)で動作させた場合の比較
ve are unnecessarily lengthened due to channel noise.
ence Primitive w/o 802.11 w/ 802.11 Increase
that employ Operation interference interference in Current
c is that they TinyOS LPL 175 µA 3,030 µA 17.3×
luding inter- RI-MAC LPP 383 µA 12,576 µA 54.7×
research has A-MAC LPP 206 µA 230 µA 1.12×
on the effec- Hui LPL 36 µA† 72 µA‡ 2.0ׇ
how that sig-
cted and ac- Table 1. The effect of interference on idle listening cur-
20 20 20 20
periments 15
to rent. The average current draw of three different syn-
chronization schemes under no-load conditions and a 15
15 15
Current (mA)
Current (mA)
Current (mA)
Current (mA)
yer operation
10
500 ms check/probe interval. Results are the average of 10
10 10
in which we
5
five samples, each one minute long. Although the LPL ex- 5
5 5
an office en- 500 hibits 1500 lowest power 10 15 ideal conditions, both the 0
the under
0 0 0 0
on schemes,
0
TinyOS LPL and RI-MAC LPP exhibit dramatic3000
1000
Time (ms)
0 5
Time (ms)
0 1000
Time (ms) power
2000 50 100
Time (ms)
150
increases under (b) LPL sample detail
P, under(a) LPL sampling (no interfer-
two interference while(c) LPL sampling (w/ mech- (d) LPL overhearing detail
A-MAC’s LPP interfer-
ence) ence)
out a nearby 10. LPL preamble sampling techniques leave receivers susceptible to noisyshows environments, such as those
anism shows a relatively negligible increase which 37
Figure A-MAC’s low-power probing is resilient to false positives. wireless
