Information Theory for Mobile Ad-Hoc Networks (ITMANET): The FLoWS Project

Thrust 2 Layerless Dynamic Networks

Lizhong Zheng, Todd Coleman

Capacity Delay

Power

Upper Bound

Lower Bound

Capacity and Fundamental Limits

Capacity

Delay

Power

Utility=U(C,D,E)

Application and Network Optimization

(C*,D*,E*)

Constraints

Degrees ofFreedom

Models andDynamics

Application Metrics and

Network Performance

LayerlessDynamic Networks

New Paradigmsfor Upper

Bounds

MANET Metrics

Fundamental Limitsof Wireless Systems Application Metrics

Models

New MANET Theory

Metrics

Layerless Dynamic Networks

• Dynamic : Separation of functionalities by different time scales no longer optimal. – Time varying channel/network environments, lack of information, high

overhead costs;– Data/side information available in a variety of forms, with a wide range of

quality/precision/reliability;– Broadcasting and interference, beyond point-to-point communications;

• Layerless: New signaling schemes, new metrics– Network information theory: cooperative/cognitive transmissions, relay and

soft information processing;– Dynamic information exchange, feedbacks and multi-way communication;– Heterogeneous data processing, prioritizing data by different levels of

reliability; networking based on new interface to the physical layer;– The principle of network coding, transmit-collect-combine pieces of

information, generalized form and coordination in dynamic networks;– Operating with imperfect side information, robustness and universal

designs.

Thrust Areas

• Network information theory– Multi-terminal communication schemes with cooperative and

cognitive signaling, interference mitigation, broadcast/relay;

• Generalizing network coding

• Structured code designs– Efficient transmission of heterogeneous data and applications;

• Universal and robust algorithms

• Feedback and dynamic communication problems

Recent Thrust Achievements:Relaying, forwarding, and combining soft information

• Likelihood forwarding – Koetter

• General relaying for multicast – Goldsmith

• Interference forwarding -- Goldsmith

• Broadcasting Channel with Cognitive Relay – Goldsmith

• Multicasting with relay – Goldsmith– Structured codes based on the structure of the network;– Finite field channel / linear codes vs. Gaussian channel / nested

lattice codes

• Sum capacity for deterministic interference channels -- El Gamal

• Broadcasting Channel with 3+ receivers – El Gamal (focus talk)

• Analytical study for zig-zag decoding -- Medard

Recent Thrust Achievements:Structured codes and Applications

• Broadcasting with layered source codes – Goldsmith

• Generalized capacity/distortion for joint source channel codes – Effros & Goldsmith

• UEP: performance limits and applications – Zheng

• Joint source channel coding with limited feedback -- Goldsmith

– Successive refinement with progressive transmissions– Dynamic of channel blocks between layers

• Distortion-outage tradeoff -- Medard & Zheng– Comparison between multiple description and multi-resolution

codes– New interface to the physical layer

• Low complexity channel coding with Polar codes – Effros

Recent Thrust Achievements:Generalized Network Coding

• Generalization to finite state broadcast channels (FSBC) - Goldsmith

• Control principles for feedback channels – Coleman• Dynamic coding problem interpreted with stochastic control • Reverse iterated function system (RIFS) decoding algorithms (w/

linear complexity) achieve capacity• Lyapunov exponents of dynamical systems provide clean way to

demonstrate how posterior matching achieves capacity• Tilted posterior matching for feedback channels

-- Zheng (focus talk)

• Joint source channel code with outage, with limited feedback-- Goldsmith

• Exploiting mobility in relay networks -- Moulin

Recent Thrust Achievements:Feedback, channel memory, and dynamics

Provide building blocks for large networks, translate design constraints into network modeling assumptions

Thrust Synergies

Thrust 2Dynamic Network Information theory: improving performance in presence of interference, cooperation, and dynamic environment

Thrust 3

Application Metrics and Network Performance

Guide problem formulation by identifying application constraints and relevant performance metrics

Provide achievable performance region, based on which distributed algorithms and resource allocation over large networks are designed

Thrust 1

New Paradigm of outer boundsPerformance benchmark and design justification

General Relaying, interference forwarding

-- Goldsmith

Posterior matching for feedback channels – Coleman, Zheng

Joint source channel coding with outage

– Goldsmith

Network scalability, robust and distributed algorithms

Dynamic Network Information Theory

CSI, feedback, and robustness Structured coding

Thrust 2 Achievements Overview

Goldsmith: general relaying, soft combining

Zheng: Mismatched receivers Goldsmith: Broadcasting with layered code

Effros: two stage polar codes Moulin: Universal Decoding in MANETs

Goldsmith: Feedback and Directed Information

Coleman: Control principle for feedback channels

Zheng: tilted matching for feedback channels

Medard, Zheng: Diversity-distortion tradeoff

Goldsmith: Joint source channel coding / outage

Effros: linear representation of network coding

Goldsmith: Interference forwarding

Cover: coordination capacity

El Gamal: BC with 3+ receivers

Effros: distributed network coding with coded side information

Goldsmith: Multicast with relay; BC with cognitive relay Moulin: exploiting mobility

of relay networks

Thrust Achievement Summary1. Revolutionize upper bounding techniques (thrust 1)2. Determine the optimal channel/network “coding” that achieves these capacity upper

bounds when possible, and characterize for which classes of networks gaps still exist between achievability and upper bounds, and why.

– Coordination capacity – Cover (focus talk);

3. Develop new achievability results for key performance metrics based on networks designed as a single probabilistic mapping with dynamics over multiple timescales

– General framework for systematic development and comparison of signaling schemes– New metrics and new interfaces

• Error-erasure, distortion-outage, joint source channel codes;– New signaling techniques

• Generalized network coding, soft information combining, interference management;• Message embedding, layered codes;• Robust and universal algorithms;• Dynamic communication problems, feedback, mobility;

4. Develop a generalized theory of rate distortion and network utilization (thrust 3)5. Demonstrate the consummated union between information theory, networks, and

control; and why all three are necessary ingredients in this union.– Large network results;– Control view of dynamic information exchange

Thrust Challenges• Formulations beyond capacity

– Philosophical alignment of achievability and converse methodologies– Bounds vs. approximations– New metrics focusing on delays and robustness– Hidden dimensions of limits

• Coordination and Networks– Not all communication has to be reliable: how to measure/utilize soft

information for end-to-end reliability?– Robustness and imperfect side information– Coordination overhead

• Coded side info. / unintended helper / confidential messages• Feedback and dynamic communication problems: are rate and error

exponent the right metrics?

• Impacts and insights to practical problems