JENNA: a Jamming Evasive Network-coding Neighbor

Dynamic Spectrum Access/Cognitive Radio Networks
Single Hop Networks
MAC
Control
protocol channel
Primary User
Detection
Multi Hop Networks
Neighbor
Discovery
CC for limited Spectrum-aware
size networks clustering protocol
MAC
protocol
Spectrum
Reuse
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

Nodes operate over multiple channels
Limited spectrum resources shared with:
› Primary users
 Assure interference-free communications
› Primary user emulation attackers (static jammers)
 Detection and neighbor advertisement
› Random hopping attackers (reactive jammers)
 Prompt evasion of jammed channel
< step prior to network deployment
First
Neighbor Discovery
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
Need not know actual number of nodes, n.
› Nodes know the label set size N and channel
set M

Follow deterministic channel hopping
patterns
› Use round-robin pattern easy to detect
› Easy for jammers to disrupt neighbor
discovery
› Hopping pattern spans over all channels M

Guarantee neighbor discovery in finite time
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Requires knowledge of number of nodes n
Nodes are globally time-synchronized (GPS)
Different pseudo-random hopping patterns
› Single Frequency Channel selection (Caval = 1)
 Fast neighbor discovery
 Susceptible to reactive jamming attacks
› Pseudo-random channel hopping (SLF scheme)
 Slow neighbor discovery
 Robust to jamming attacks
› Other hopping patterns with reduced neighbor
discovery delay but susceptible to jamming
attacks (internal jammers or compromised
nodes).
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
Randomized algorithm
› Nodes hop randomly over Caval

Fully distributed
› No central entity for coordination

Asynchronous time-slotted architecture
› need no global time synchronization among
nodes
Does not require to know n to terminate
 Assure faster neighbor discovery w.h.p.

› Discovery delay depends on number of
nodes, n

Very robust to jamming attacks
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
Node wake up (Idle mode)
› Spectrum scanning phase
 Energy detection
 Cyclo-stationary feature detection
 Matched filter etc.
› Prior to first transmission (or after first packet reception)
include all gathered data in the ctrl packet and store
it in the buffer.

Active mode
› Transmit randomly in channel c in Cfree every slot if
channel is sensed free otherwise defer transmission
› Transmitted packets are linear combinations of the
packets stored in the buffer so far.
› On receiving a packet store it in the buffer and
perform Gaussian elimination to the decoding matrix.
› If matrix has full rank activate time-out period T.
Afterwards consider neighbor discovery terminated.
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channels
nodes
5
5
4
3
2
1
10
7
J1
6
P1
8
8
J1 J1
8
J1
7
J1
8 J1
5
6
8
8
J1
3
9
J1
1
J1
J1 7
3 J1
2 8
6
1
J1 J1
4
5
7
6
9
2
5
7
2
1
3
8
J1 J1
time [slots]
2
3
9
6
1
7
4
10
5
8
IDLE
ACTIVE
Rall estimate
scanning
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transition phase
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DET : Deterministic algorithm M*n*log(N)
 RMS : Random Message Selection

› Nodes send a random packet in their buffer

SLF : Selfish
› Nodes send only their packet

GF(x) Unsync: NetCod Unsynchronized
› Discovery ends independently for each node

GF(x) Sync: NetCod Synchronized
› Discovery ends at the same time-slot
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We propose a neighbor discovery algorithm
for single hop cognitive radio networks, able
to provide full neighbor discovery in a timeasynchronous and distributed way.
Future work is looking towards the extension
of the algorithm to multi-hop cognitive radio
networks
Provide a joint solution for neighbor
discovery and cluster formation in very
challenging wireless environments
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