1. Information Theory for Mobile Ad-Hoc Networks (ITMANET): The FLoWS Project FLoWS Overview and Update Andrea Goldsmith

2. 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.

3. Limitations in theory of MANETs today –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. Wireless Information Theory Wireless Network Theory Optimization Theory B. Hajek and A. Ephremides, “Information theory and communications networks: An unconsummated union,” IEEE Trans. Inf. Theory, Oct. 1998.

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

5. 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.

6. Capacity Delay Energy Upper Bound Lower Bound Capacity and Fundamental Limits Application Metrics Capacity Delay Energy/SNR Utility=U(C,D,E) Source Coding and Network Utility (C*,D*,E*) Constraints Degrees of Freedom Models and Dynamics Application Metrics and Network Performance Layerless Dynamic Networks New Paradigms for Upper Bounds Models New MANET Theory MANET Metrics Metrics Fundamental Limits of Wireless Systems

7. 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

8. Structured Coding Thrust Synergies and New Intellectual Tools New Bounding Techniques Optimization Code Construction Combinatorial Tools Dynamic Network IT Thrust 1 Thrust 2 Game Theory Thrust 3 Optimization Stochastic Network Analysis CSI, Feedback, and Robustness

9. 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.

10. Thrust 0 Achievements Metrics Effros, Goldsmith: Expectation and Outage in Capacity and Distortion Zheng, Medard: Distortion-diversity tradeoffs Ozdaglar, Medard: Downloading delay Boyd, Ozdaglar, Medard, Goldsmith: End-to-end optimization metrics subject to specific constraints (e.g. delay) Models Coleman, Medard, Koetter, Effros, Goldsmith : Capacity Regions Goldsmith: Diversity/multiplexing/delay tradeoffs Moulin: Error-erasure tradeoffs Zheng: Error exponents Goldsmith:Finite State Markov Dynamics Boyd, Effros, Goldsmith, Zheng: Fading with/without CSI 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

11. New bounding techniques Thrust 1 Achievements Goldsmith, Medard, Katabi: analog network coding Koetter: likelihood forwarding Medard, Koetter: network coding capacity via conflict graphs Moulin: covert channel by timing information Koetter, Effros, Medard: Equivalence classes of networks based on emulation of a channel or a building block by arbitrary channels, including multipoint channels Goldsmith: Interference channel with cognitive user, “asymmetric” cooperation Effros, Koetter: A characterization of the source coding region of networks for “line networks” Code construction Network information theory Networking and optimization Combinatorial Tools Ozdaglar, Medard: Rate allocation in multiple access networks Zheng, Medard: New techniques to unify multiple description and multi-resolution, distortion-diversity Zheng: error exponents unequal error protection, embedded control messages to reduce overhead. Ozdaglar, Medard: Network coding for downloading delay Ozdaglar, Medard: Cross-layer optimization under different metrics and constraints Goldsmith, Effros: generalized capacity and source-channel coding

12. Goldsmith: general relaying, soft combining Goldsmith: Cognitive users and interference Zheng: Embedded Coding and UEP Moulin: Information flow via timing Goldsmith: Broadcasting with layered codes Coleman: Joint Source/Channel Coding in Networks Dynamic Network Information Theory CSI, feedback, and robustness Structured coding Effros, Goldsmith: Generalized capacity, distortion, and joint source/channel coding. Thrust 2 Achievements Zheng: Euclidean Information Theory Goldsmith: Degraded FS Broadcast Channels Moulin: Universal Decoding in MANETs Goldsmith: Feedback and Directed Information Coleman: Rate Distortion of Poisson Processes Moulin: Error/erasure tradeoff for compound channel Goldsmith: DMT for multi-hop networks Coleman: “E-type” broadcasting channels Zheng: Message embedding in feedback channels Medard, Zheng: Diversity-distortion tradeoff Goldsmith: Interference forwarding

13. Thrust 3 Achievements Shah: Low complexity throughput and delay efficient scheduling Ozdaglar: Distributed optimization algorithms for general metrics and with quantized information Johari: Local dynamics for topology formation Meyn: Generalized Max-Weight policies with performance optim- distributed implementations Goldsmith, Johari: Game-theoretic model for cognitive radio design with incomplete channel information Boyd, Goldsmith: Wireless network utility maximization (dynamic user metrics, random environments and adaptive modulation ) Optimization Theory Distributed efficient algorithms for resource allocation Stochastic Network Analysis Flow-based models and queuing dynamics Game Theory New resource allocation paradigm that focuses on hetereogeneity and competition Medard, Ozdaglar: Efficient resource allocation in non-fading and fading MAC channels using optimization methods and rate-splitting Shah: Capacity region characterization through scaling for arbitrary node placement and arbitrary demand Ozdaglar: Competitive scheduling in collision channels with correlated channel states Medard, Ozdaglar: Cross-Layer optimization for different application delay metrics and block- by-block coding schemes Boyd: Efficient methods for large scale network utility maximization Goldsmith: Layered broadcast source-channel coding Medard, Shah: Distributed functional compression

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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)

21. 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.htmhttp://www.stanford.edu/~adlakha/ITMANET/flows_publications.htm

22. 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)