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

The FLoWS Project

FLoWS Overview and Update

Andrea Goldsmith

DARPA’s ITMANET Challenge

• Develop and exploit a more powerful information theory for mobile wireless networks. • Anticipated byproducts include new separation theorems to inform wireless network "layering" as well as new protocol ideas.

Hypothesis: A better understanding of MANET capacity limits will lead to better network design and deployment.

Limitations in theory of MANETs today

Wireless Information Theory Wireless Network Theory Optimization Theory

– Success on narrowly-defined information theory of wireless networks.

– Large body of wireless (and wired) network theory that is ad-hoc, lacks a basis in fundamentals, and lacks an objective success criteria.

– Little cross-disciplinary work spanning these fields, except applying optimization techniques to existing wireless network designs.

Our Approach: Consummating Unions Wireless Information Theory Wireless Network Theory Optimization Theory

• When capacity is not the only metric, a new theory is needed to deal with nonasymptopia (i.e. delay, random traffic) and application requirements – Shannon theory generally breaks down when delay, error, or user/traffic dynamics must be considered • Fundamental limits are needed outside asymptotic regimes • Optimization provides the missing link to address these issues

FLoWS Program Objectives

•

Develop tractable and insightful metrics and models for MANET information theory.

•

Define fundamental performance limits for MANETs in terms of desired objective metrics.

•

Obtain upper and lower performance bounds for these metrics for a given set of MANET models.

•

Define the negotiation between the application and network for resource allocation and performance optimization of our given metrics

•

Bound the cost of using our set of metrics as the interface between the network and applications.

MANET Metrics New Paradigms for Upper Bounds Layerless Dynamic Networks Application Metrics and Network Performance Capacity and Fundamental Limits Capacity Upper Bound Delay Lower Bound Energy Source Coding and Network Utility Capacity

(C*,D*,E*)

Delay

Utility=U(C,D,E)

Energy/SNR Fundamental Limits of Wireless Systems Application Metrics Constraints Models and Dynamics Degrees of Freedom Metrics Models New MANET Theory

Thrust Objectives and Rationale

•

Models and Metrics

(Leads: Effros and Goldsmith): –

Objective:

Develop a set of metrics for dynamic networks that capture requirements of current and future applications –

Rationale:

Models for MANETs are needed that are tractable yet lead to general design and performance insights • •

New Paradigms for Upper Bounds

(Leads: Koetter and Medard) –

Objective:

Obtain bounds on a diversity of objectively-defined metrics for complex interconnected systems.

–

Rationale:

A comprehensive theory for upper bounding the performance limits of MANETs will help guide design

Layerless Dynamic Networks

– – (Lead: Zheng)

Objective:

Design of networking strategies as a single dynamic probabilistic mapping, without pre-assigned layered structure

Rationale

Remove layering and statics from MANET theory. •

End-to-End Metrics and Performance

– (Leads:Ozdaglar and Shah)

Objective

: Provide an interface between application metrics and network performance –

Rationale:

A theory of generalized rate distortion, separation, and network optimization will improve application performance

Thrust Synergies and New Intellectual Tools

Thrust 1

New Bounding Techniques Code Construction Combinatorial Tools Optimization Dynamic Network IT

Thrust 3 Thrust 2

Structured Coding Optimization Stochastic Network Analysis Game Theory CSI, Feedback, and Robustness

Progress since December

• New breakthroughs in generalized capacity and separation, robust source and channel coding, equivalence classes, scaling laws, wireless NUM, cross-layer optimization, and distributed resource allocation. • New synergies within and between our thrust areas • New and ongoing collaborations among PIs • Overview paper for Scientific American – Co-authors: Effros, Goldsmith, Medard – Paper near completion, will be submitted next month • JSAC Tutorial on MANET Capacity with Cognitive Radios – Co-authors: Goldsmith, Jafar, Maric, and Srinivasa – Paper accepted for publication, to appear in 2009. • Website updated with Dec. PI meeting slides, recent publications, and recent results.

Thrust 0 Achievements

Models

Boyd, Effros, Goldsmith, Zheng

: Fading with/without CSI

Goldsmith:

Finite State Markov Dynamics

Boyd, Goldsmith, Ozdaglar, Johari:

General Network State Distributions

Shah:

Arbitrary node placement and traffic

Boyd, Effros, Goldsmith, Koetter, Ozdaglar, Shah:

General traffic models, including multicast traffic

Effros, Goldsmith:

Expectation and Outage in Capacity and Distortion

Goldsmith:

Diversity/multiplexing/delay tradeoffs

Coleman, Medard, Koetter, Effros, Goldsmith :

Capacity Regions

Boyd, Ozdaglar, Medard, Goldsmith:

End-to-end optimization metrics subject to specific constraints (e.g. delay)

Ozdaglar, Medard:

Downloading delay

Moulin:

Error-erasure tradeoffs

Zheng:

Error exponents

Zheng, Medard:

Distortion-diversity tradeoffs

Metrics

Thrust 1 Achievements

Zheng:

error exponents unequal error protection, embedded control messages to reduce overhead.

Effros, Koetter:

A characterization of the source coding region of networks for “line networks”

Koetter:

likelihood forwarding

Zheng, Medard:

New techniques to unify multiple

Code construction

description and multi-resolution, distortion-diversity

Koetter, Effros, Medard:

channels, Equivalence classes of networks based on emulation of a channel or a building block by arbitrary including multipoint channels

Network information theory New bounding techniques

Goldsmith:

Interference channel with cognitive user, “asymmetric” cooperation

Moulin:

covert channel by timing information

Goldsmith, Effros:

generalized capacity and source-channel coding

Goldsmith, Medard, Katabi:

analog network coding

Ozdaglar, Medard:

Cross-layer optimization under different metrics and constraints

Ozdaglar, Medard:

Network coding for downloading delay

Ozdaglar, Medard:

Rate allocation in multiple access networks

Medard, Koetter:

network coding capacity via conflict graphs

Networking and optimization Combinatorial Tools

Thrust 2 Achievements

Dynamic Network Information Theory Goldsmith:

general relaying, soft combining

Goldsmith:

Interference forwarding

Goldsmith:

Degraded FS Broadcast Channels

Coleman:

Rate Distortion of Poisson Processes

Goldsmith:

DMT for multi-hop networks

Zheng:

Euclidean Information Theory

Moulin:

Information flow via timing

Coleman:

“E-type” broadcasting channels

Goldsmith:

Feedback and Directed Information

Goldsmith: Moulin:

Error/erasure tradeoff for compound channel Cognitive users and interference

Medard, Zheng:

Diversity-distortion tradeoff

Coleman:

Joint Source/Channel Coding in Networks

Moulin:

Universal Decoding in MANETs

Zheng:

Message embedding in feedback channels

Effros, Goldsmith

: Generalized capacity, distortion, and joint source/channel coding .

Zheng:

Embedded Coding and UEP

CSI, feedback, and robustness Goldsmith:

Broadcasting with layered codes

Structured coding

Thrust 3 Achievements

Boyd:

Efficient methods for large scale network utility maximization

Goldsmith:

Layered broadcast source-channel coding

Medard, Shah:

Distributed functional compression

Boyd, Goldsmith:

Wireless network utility maximization (dynamic user metrics, random environments and adaptive modulation )

Ozdaglar:

Distributed optimization algorithms for general metrics and with quantized information

Shah:

Capacity region characterization through scaling for arbitrary node placement and arbitrary demand

Shah:

Low complexity throughput and delay efficient scheduling

Meyn:

Generalized Max-Weight policies with performance optim- distributed implementations

Optimization Theory

Distributed efficient algorithms for resource allocation

Medard, Ozdaglar:

different application delay metrics and block by-block coding schemes

Medard, Ozdaglar:

Efficient resource allocation in non-fading and fading MAC channels using optimization methods and rate-splitting

Goldsmith, Johari:

cognitive radio design with incomplete channel information

Johari: Ozdaglar:

Cross-Layer optimization for Game-theoretic model for Local dynamics for topology formation Competitive scheduling in collision channels with correlated channel states

Stochastic Network Analysis

Flow-based models and queuing dynamics

Game Theory

New resource allocation paradigm that focuses on hetereogeneity and competition

Focus Talks and Posters

•

Thrust 1:

– Koetter: A tool oriented approach to network capacity (joint with Effros and Medard) •

Thrust 2:

– Goldsmith: Interference in MANETs:

Friend or Foe?

•

Thrust 3:

– Shah: Capacity region of large wireless networks (joint with Neisen and Gupta)

• Posters on all new (green) results

Progress Criteria: Phase 1 (completed)

• Upper and lower bounds characterization of n(n-1) capacity region for small networks with simple assumptions –

Koetter, Effros, Medard:

Equivalence classes of networks based on ability of a channel or a building block to emulate arbitrary channels –

Goldsmith, Medard, Katabi:

Joint relaying, combine symbols in PHY, bits, or network layer • Scaling and achievability results for large networks with fixed traffic –

Shah:

Optimal capacity scaling for arbitrary node placement and arbitrary multi-commodity flows –

Shah:

multiple access decomposition for constructive scaling laws • Analysis of tractability vs. practicality of channel models and robustness to modeling assumptions and system uncertainty –

Meyn, Zheng, Medard:

mismatched receiver, online robust algorithm to combat imperfect channel info.

–

Goldsmith:

Broadcasting with layered source code, graceful degradation for weaker users • Joint characterization of trade-offs among delay, energy and capacity – – –

Medard, Zheng: diversity-distortion tradeoff Shah:

Low complexity throughput and delay efficient scheduling

Goldsmith, Boyd

: Capacity and delay under Wireless NUM

Progress Criteria: Phase 1 (completed)

• Study of optimized node cooperation incorporating not only virtual MIMO, cooperation diversity, conferencing, and relaying but also network coding for networks of 5-10 nodes. Includes impact of generalized decode-forward and amplify-forward (list decoding, partial decoding). Includes impact of delay, energy, and outage probability.

– –

Goldsmith:

MANET capacity w/ node cooperation and cognition

Koetter:

Likelihood forwarding • Study dynamic allocation of rate, power, and the spatial degrees of freedom associated with multiple antennas, as well as dynamic spectrum allocation –

Goldsmith, Johari:

Game-theoretic model for cognitive radio design with incomplete channel information –

Medard, Ozdaglar:

Efficient resource allocation in non-fading and fading MAC channels using optimization methods and rate-splitting • Study strengths and vulnerabilities posed by addressing jamming with cooperating and non-cooperating nodes –

Moulin, Medard

: On Manet jamming

Progress Criteria: Phase 1 (completed)

• Study fundamental limits of the ability of inside attackers to observe and contaminate degrees of freedom in a MANET –

Medard, Effros

: Byzantine’s attacks • Study systematic techniques for bounding the achievable rate region for distributed source coding in complex networks, considering issues of robustness to unknown/imperfect source and network statistics and application of universal coding and decoding techniques to such systems.

– –

Coleman:

Joint Source/Channel Coding in Networks

Effros/Koetter:

A characterization of the source coding region of networks for “line networks” • Study network-aware design; stability of network operation with respect to application-aware optimization will be studied. – –

Boyd:

Dynamic and stochastic network utility maximization with delivery constraints

Ozdaglar:

Distributed optimization algorithms for general metrics and with quantized information

Progress Criteria: Phase 2 (next 12 months)

– Evolve results in all thrust areas to examine more complex models, robustness/security, more challenging dynamics, and larger networks. • • • • • • • •

Koetter, Effros, Medard:

Network equivalence

Ozdaglar, Medard:

Rate allocation in multiple access networks

Goldsmith:

Multihop networks: Cooperation, Cognition, and Robustness Tradeoffs

Moulin:

Error/erasure tradeoff for compound channel

Zheng:

Message embedding in feedback channels

Coleman:

“E-type” broadcasting channels

Johari:

Local dynamics for topology formation

Meyn:

Generalized Max-Weight policies with performance-optimal distributed implementations •

Shah:

Capacity scaling laws for arbitrary node placement and arbitrary demand – Demonstrate synergies between thrust areas: compare and tighten upper bounds and achievability results for specific models and metrics; apply generalized theory of distortion and utility based on performance regions developed in Thrusts 1-2. • • • •

Ozdaglar, Medard:

Cross-layer optimization under different metrics

Zheng, Medard:

Unifying multiple description and multi-resolution, distortion-diversity

Boyd, Goldsmith:

Wireless NUM with cooperative PHY

Medard, Ozdaglar:

Cross-Layer optimization for different application delay metrics and block-by-block coding schemes •

Ozdaglar:

Competitive scheduling in collision channels with correlated channel states

Progress Criteria: Phase 2 (next 12 months)

– Demonstrate that key synergies between information theory, network theory, and optimization/control lead to at least an order of magnitude performance gain for key metrics. • • •

Ozdaglar, Medard:

Network coding for downloading delay

Goldsmith:

Generalized capacity, distortion, and separation

Boyd, Goldsmith:

Wireless network utility maximization – Pose clearly defined community challenges related to evolving our theory that inspires other researchers to collectively make breakthrough progress. • Community challenges posed in plenary talks and tutorials, as well as invited papers and vision papers – Publish 2 vision papers, one for the community (e.g. in the IEEE Wireless Communications Magazine) and one for the broader technical community (e.g. in Nature or Science) illuminating our ideas, results, and their potential impact • Draft paper for Scientific American near completion. To be submitted in Oct.

• Outline of community paper will be discussed in Friday team meeting

Project Impact To Date

• Plenary Talks and Panels – Boyd: Dysco’07, S. Stevun Lecture’08, CNLS’08, ETH’08 – Effros: ISIT’07 – Goldsmith: ACC’07, Gomachtech’08, ISWPC’08, Infocom’08, LTE Wshp’09 – Medard: Gretsi’07, CISS’07, NRC’07, IT Winter School’08 – Koetter: ITW’07, WiOPT’08 – Meyn: Erlang Centennial’09 • Recent Tutorials – Boyd: MOCCS’08, WOSP’08 – Ozdaglar: Networks' challenge: Where game theory meets network optimization (ISIT’08) – Medard/Koetter: Intro. to Network Coding (PIMRC’08) – Maric/Dabora: Cooperation in Wireless Networks (PIMRC’08) • Conference Session/Program Chair – ISIT’07 Technical Program (Chairs: Medard and Goldsmith) – CTW’08 session (Chairs: Andrews and Goldsmith) • Invited journal papers – “Breaking spectrum gridlock through cognitive radios: an information theoretic approach”, IEEE Proc’09 (w/ Jafar, Maric, and Srinivasa)

Publications to date

• 10 accepted journal papers, 10 more submitted • 80 conference papers (published or to appear) • Publications website: – http://www.stanford.edu/~adlakha/ITMANET/flows_publications.htm

Summary

• Significant progress on all thrust areas • Significant progress on synergies between thrust areas • Ongoing and fruitful collaborations between PIs • Roadmap towards meeting Phase 2 goals underway • Significant impact of FLoWS research on the broader research community (IT, communications, networking, and control/optimization)