Download presentation
Presentation is loading. Please wait.
1
Effectively Capturing Attention Using the Capture Effect
Michael König Roger Wattenhofer
2
The Capture Effect
3
The Capture Effect
4
The Capture Effect – Power Difference
[“Sharing a Medium Between Concurrent Protocols Without Overhead Using the Capture Effect”, 2016]
5
The Capture Effect – Packet Timing
(weaker) (stronger) Preamble SFD Len Payload ... Preamble SFD Len Payload ... Time
6
The Capture Effect – Packet Timing
(weaker) (stronger) Preamble SFD Len Payload ... 160 µs Preamble SFD Len Payload ... Time
7
The Capture Effect – Packet Timing
8
Prior Work: Protocol Layering
9
Prior Work: Protocol Layering
-64 dBm -70 dBm -75 dBm -81 dBm Layer 4 Layer 3 Layer 2 Layer 1
10
This work: going one step further …
… beyond the granularity of packets!
11
Injecting into Longer Packets
long, latency insensitive packet latency sensitive packet (weaker) (stronger)
12
Naïve Injecting
13
Chip Sequences in IEEE Symbol … 16 µs 0.5 µs
14
Improving Symbol Alignment
TelosB clock: 4 MHz, but not stable Error Sources: Clock synchronization Transmission timing Travel time SA SB = < 0.25 µs (75%) S < 0.25 µs R SA SB < µs
15
Improved Symbol Alignment
16
Symbol Descrambling Repairing Mapping
m(s, a) = s – (s mod 8) + ((s + a) mod 8) for 0 ≤ a < 8
17
Symbol Descrambling Interpret 4 chips late 00 11 22 33 44 55 66 77 88
99 aa bb cc dd ee ff 16 18 20 12 14 1 2 3 4 5 6 7 8 9 a b c d e f
18
Symbol Descrambling Interpret 6 chips late 00 11 22 33 44 55 66 77 88
99 aa bb cc dd ee ff 16 14 18 1 2 3 4 5 6 7 8 9 a b c d e f
19
Symbols Descrambled
20
Overview Packet Injection
Loose Synchronization Tight Synchronization No Mapping | With Mapping No Mapping | With Mapping
21
We can decouple the synchronization header from the payload!
Generalized Result We can decouple the synchronization header from the payload! (for a price) Sync Header ... Sender A Sender B Data Sender C Len
22
Application: Chasm Crossing
23
Wakeup Headers
24
Combining Weak Packets
1b1f21ffdedededededededededededededededededede 1b1f229fd3dedededededeeed2dedddededededede8ede 1b1f21ffdeded4dededededededededededededededede 1b1f21ffde2ede1ed77eddd92ed2ded0deded7dede6e94
25
Chasm Crossing Results
26
Chasm Crossing Results
No Wakeup Wakeup Wakeup + Mapping
27
Chasm Crossing Results
a Complete Copy was Reassembled Fraction of Cases in which
28
Future Work Beyond proof of concept, integrate into MACs
Transfer to other hardware and wireless specifications
29
Summary Sender A Sender B Sender C Sync Header ... Data Len 00 11 22
33 44 55 66 77 88 99 aa bb cc dd ee ff 16 18 20 12 14 1 2 3 4 5 6 7 8 9 a b c d e f
30
Questions Michael König
Similar presentations
