1. Providing Real-time Security Support for Multi-level Ad-hoc Networks
Jiejun Kong, Mario Gerla
Computer Science Department
University of California, Los Angeles

2. Real-time Security Support: Characteristics
Capable of processing vast amount of data in short period
Raises performance concerns on mobile devices
This work studies performance aspects of security solutions in mobile ad hoc networks
Delay sensitive
Packets that incur an extra end-to-end delay are essentially useless
Loss-tolerant (nearly solved)
Occasional data loss/corruption only causes insignificant glitches
Solutions: TESLA, IPsec/ESP
What does “adaptive” mean here? ……

3. Mobile Real-time Applications
Mobile real-time data collector
Useful in tactical environments, paramedic emergency, news report, personal communications
On-device encoding and encryption
Motivation 1.
Mobile client of multimedia streaming
Pocket TV broadcasting
On-device decryption and decoding

4. Application Domain: Digital Battlefields
Level 1: Regular Ground Nodes
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Level 3: Aerial Mobile Backbone
Level 2: Ground Mobile Backbone

5. Multi-level Heterogeneous Ad-hoc Networks
Problem of homogeneous mobile ad-hoc networks
Network capacity approaches 0 when network scale increases
Multi-level heterogeneous ad-hoc network provides scalability and throughput guarantees
Regular ground nodes
Ground mobile backbone (MBN nodes)
Aerial mobile backbone structure (UAV nodes)
Network capacity approaches the bottleneck link capacity
E.g., 11Mbps in b, 54Mbps in a

6. Communication Bandwidth  vs. Computation Bit-rate 
Communication bandwidth t
Max: W
Min: 0
Capacity of a MANET with N nodes: (N)
Computation processing bit-rate t
Must catch up with t t = t
Otherwise packet drop-off or buffer overflow

7. Communication Bandwidth  vs. Computation Bit-rate  (detail)
Major processing overheads come from
Operation A: compression (of encoding)
Operation B: encryption (of security protection)
A is limited due to heavy workload
352x240 resolution image, 24-bit color, 30frame/sec  60Mbps
On-device compression 60Mbps  1.5Mbps MPEG stream
B is limited due to inflexible encryption schemes designed for large servers
When t is at the scale of Mbps speed, can t catch up with t ?

8. Experiments on Mobile Device
iPAQ3670, Intel StrongARM 206MHz CPU, 16M ROM, 64M RAM

9. Case Study: t <t ok failed
Encoding A = 2Mbps. Encryption B = measured previously. Will the overall data rate t reach the line t =1.5Mbps (MPEG I)?

10. Proposals Call for rate-adaptive security protection
Notion of adaptive “real-time” protection
Actual protection varies with network condition
Yet, a guaranteed lower-bound on protection
Data (adaptable
rate/content)
secured data
secret
Adaptable strength
Adaptable bitrate
Security Module
(adaptable)
(bandwidth estimation etc.)
network feedback