Balaji Prabhakar
Professor of Electrical Engineering and of Computer Science and, by courtesy, of Management Science and Engineering and of Operations, Information and Technology at the Graduate School of Business
Bio
Prabhakar's research focuses on the design, analysis, and implementation of data networks: both wireline and wireless. He has been interested in designing network algorithms, problems in ad hoc wireless networks, and designing incentive mechanisms. He has a longstanding interest in stochastic network theory, information theory, algorithms, and probability theory.
Academic Appointments

Professor, Electrical Engineering

Professor, Computer Science

Professor (By courtesy), Management Science and Engineering

Professor (By courtesy), Operations, Information & Technology

Affiliate, Precourt Institute for Energy
Professional Education

PhD, UCLA (1994)
201516 Courses
 Analysis and Modeling of Big Data from Things That Move
EE 392K (Win)  Introduction to Statistical Signal Processing
EE 278 (Spr) 
Independent Studies (25)
 Advanced Reading and Research
CS 499 (Aut, Win, Spr, Sum)  Advanced Reading and Research
CS 499P (Aut, Win, Spr, Sum)  Computer Laboratory
CS 393 (Aut, Win, Spr, Sum)  Curricular Practical Training
CS 390A (Aut, Win, Spr, Sum)  Curricular Practical Training
CS 390B (Aut, Win, Spr, Sum)  Curricular Practical Training
CS 390C (Aut, Win, Spr, Sum)  Independent Database Project
CS 395 (Aut, Win, Spr, Sum)  Independent Project
CS 399 (Aut, Win, Spr, Sum)  Independent Project
CS 399P (Aut, Win, Spr, Sum)  Independent Work
CS 199 (Aut, Win, Spr, Sum)  Independent Work
CS 199P (Aut, Win, Spr, Sum)  Master's Thesis and Thesis Research
EE 300 (Aut, Win, Spr)  PartTime CPT
CS 390S (Aut)  PartTime CPT
CS 390T (Win)  PartTime Curricular Practical Training
CS 390Q (Spr)  PartTime Curricular Practical Training
CS 390U (Spr)  Parttime Curricular Practical Training
CS 390P (Win, Spr)  Programming Service Project
CS 192 (Aut, Win, Spr, Sum)  Senior Project
CS 191 (Aut, Win, Spr, Sum)  Special Studies and Reports in Electrical Engineering
EE 191 (Aut, Win, Spr)  Special Studies and Reports in Electrical Engineering
EE 391 (Aut, Win, Spr, Sum)  Special Studies and Reports in Electrical Engineering (WIM)
EE 191W (Aut, Win, Spr)  Special Studies or Projects in Electrical Engineering
EE 190 (Aut, Win, Spr)  Special Studies or Projects in Electrical Engineering
EE 390 (Aut, Win, Spr, Sum)  Writing Intensive Senior Project (WIM)
CS 191W (Aut, Win, Spr)
 Advanced Reading and Research

Prior Year Courses
201314 Courses
 Designing LargeScale Nudge Engines
OIT 558 (Win)
201213 Courses
 Incentive Mechanisms for Societal Networks
OIT 258 (Win)  Introduction to Statistical Signal Processing
EE 278B (Aut)
 Designing LargeScale Nudge Engines
All Publications
 EyeQ: Practical Network Performance Isolation for the Multitenant Cloud REM 2013; 1005 (A1): A2
 INSINC: A Platform for Managing Peak Demand in Public Transit Land Transport Authority, Journeys 2013
 Deconstructing Datacenter Packet Transport 2013

The Regulation of Ant Colony Foraging Activity without Spatial Information
PLOS COMPUTATIONAL BIOLOGY
2012; 8 (8)
Abstract
Many dynamical networks, such as the ones that produce the collective behavior of social insects, operate without any central control, instead arising from local interactions among individuals. A wellstudied example is the formation of recruitment trails in ant colonies, but many ant species do not use pheromone trails. We present a model of the regulation of foraging by harvester ant (Pogonomyrmex barbatus) colonies. This species forages for scattered seeds that one ant can retrieve on its own, so there is no need for spatial information such as pheromone trails that lead ants to specific locations. Previous work shows that colony foraging activity, the rate at which ants go out to search individually for seeds, is regulated in response to current food availability throughout the colony's foraging area. Ants use the rate of brief antennal contacts inside the nest between foragers returning with food and outgoing foragers available to leave the nest on the next foraging trip. Here we present a feedbackbased algorithm that captures the main features of data from field experiments in which the rate of returning foragers was manipulated. The algorithm draws on our finding that the distribution of intervals between successive ants returning to the nest is a Poisson process. We fitted the parameter that estimates the effect of each returning forager on the rate at which outgoing foragers leave the nest. We found that correlations between observed rates of returning foragers and simulated rates of outgoing foragers, using our model, were similar to those in the data. Our simple stochastic model shows how the regulation of ant colony foraging can operate without spatial information, describing a process at the level of individual ants that predicts the overall foraging activity of the colony.
View details for DOI 10.1371/journal.pcbi.1002670
View details for Web of Science ID 000308553500045
View details for PubMedID 22927811

Asymptotic independence of queues under randomized load balancing
QUEUEING SYSTEMS
2012; 71 (3): 247292
View details for DOI 10.1007/s1113401293110
View details for Web of Science ID 000305730300002
 EyeQ: Practical Network Performance Isolation at the Edge 2012
 Less Is More: Trading a Little Bandwidth for UltraLow Latency in the Data Center 2012
 Stability Analysis of QCN: The Averaging Principle 2011
 Analysis of DCTCP:Stability, Convergence, and Fairness 2011

Data Center TCP (DCTCP)
ASSOC COMPUTING MACHINERY. 2010: 6374
View details for DOI 10.1145/1851275.1851192
View details for Web of Science ID 000284879800007
 AFQCN: Approximate fairness with quantized congestion notification for multitenanted data centers 2010
 Data Center TCP (DCTCP) 2010
 Incentive mechanisms for decongesting roads 2009
 Approximate bandwidth partitioning—from academia to industry 2008
 ElephantTrap: A low cost device for identifying large flows 2007
 Detailed network measurements using sparse graph counters: The theory 2007
 Analysis of randomized load balancing with general services using the cavity method 2007

Optimal throughputdelay scaling in wireless networks  Part II: Constantsize packets
IEEEINST ELECTRICAL ELECTRONICS ENGINEERS INC. 2006: 51115116
View details for DOI 10.1109/TIT.2006.883548
View details for Web of Science ID 000241805700026

Optimal throughputdelay scaling in wireless networks  Part I: The fluid model
IEEE TRANSACTIONS ON INFORMATION THEORY
2006; 52 (6): 25682592
View details for DOI 10.1109/TIT.2006.874379
View details for Web of Science ID 000238319400019

Randomized gossip algorithms
IEEE TRANSACTIONS ON INFORMATION THEORY
2006; 52 (6): 25082530
View details for DOI 10.1109/TIT.2006.874516
View details for Web of Science ID 000238319400016
 Congestion control in networks with no congestion drops 2006
 Optimal throughputdelay tradeoff in wireless networks – Part II: Constantsize packets IEEE Transactions on Information Theory 2006; 11 (52): 51115116

SHRiNK: A method for enabling scaleable performance prediction and efficient network simulation
IEEEACM TRANSACTIONS ON NETWORKING
2005; 13 (5): 975988
View details for DOI 10.1109/TNET.2005.857080
View details for Web of Science ID 000233270900004

Systems with multiple servers under heavytailed workloads
ELSEVIER SCIENCE BV. 2005: 456474
View details for DOI 10.1016/j.peva.2005.07.030
View details for Web of Science ID 000231922700030
 Belief propagation based multiuser detection 2005
 Systems with multiple servers under heavytailed workloads 2005
 SIFT: A simple algorithm for tracking elephant flows and taking advantage of power laws 2005
 Mixing times for random walks on geometric random graphs 2005
 Network hardware algorithms 2005
 Bloom filters: Design innovations and novel applications 2005

Nearoptimal depthconstrained codes
IEEE TRANSACTIONS ON INFORMATION THEORY
2004; 50 (12): 32943298
View details for DOI 10.1109/TIT.2004.838345
View details for Web of Science ID 000225363000023

Modeling correlations in web traces and implications for designing replacement policies
COMPUTER NETWORKS
2004; 45 (4): 379398
View details for DOI 10.1016/j.comnet.2004.01.004
View details for Web of Science ID 000222046800001

Delay bounds for combined inputoutput switches with low speedup
ELSEVIER SCIENCE BV. 2004: 113128
View details for DOI 10.1016/S01665316(03)001032
View details for Web of Science ID 000187739800007
 A new proof of Parisi’s conjecture for the finite random assignment problem 2004
 Analysis and opti+A69mization of randomized gossip algorithms 2004
 Delay bounds for combined inputoutput switches with low speedup Performance Evaluation 2004; 12 (55): 113128

The existence of fixed points for the ./GI/1 queue
ANNALS OF PROBABILITY
2003; 31 (4): 22162236
View details for Web of Science ID 000186821800020

The attractiveness of the fixed points of a ./GI/1 queue
ANNALS OF PROBABILITY
2003; 31 (4): 22372269
View details for Web of Science ID 000186821800021

Randomized scheduling algorithms for highaggregate bandwidth switches
IEEEINST ELECTRICAL ELECTRONICS ENGINEERS INC. 2003: 546559
View details for DOI 10.1109/JSAC.2003.810496
View details for Web of Science ID 000182857900007

Invariant rate functions for discretetime queues
ANNALS OF APPLIED PROBABILITY
2003; 13 (2): 446474
View details for Web of Science ID 000182617800003

Approximate fairness through differential dropping
COMPUTER COMMUNICATION REVIEW
2003; 33 (2): 2339
View details for Web of Science ID 000186532800003

Incentive mechanisms for smoothing out a focused demand for network resources
COMPUTER COMMUNICATIONS
2003; 26 (3): 237250
View details for Web of Science ID 000181133200004

Entropy and the timing capacity of discrete queues
IEEEINST ELECTRICAL ELECTRONICS ENGINEERS INC. 2003: 357370
View details for DOI 10.1109/TIT.2002.807287
View details for Web of Science ID 000181265500001

Approximate fair allocation of link bandwidth
IEEE MICRO
2003; 23 (1): 3643
View details for Web of Science ID 000180930100006
 Constrained wireless scheduling: throughput, energy and delay 2003
 The attractiveness of the fixed points of a ·/GI/1 queue Annals of Probability 2003; 4 (31): 22372269
 The existence of fixed points for the ·/GI/1 queue Annals of Probability 2003; 4 (31): 22162236
 Randomized scheduling algorithms for highaggregate bandwidth switches IEEE Journal on Selected Areas in Communications 2003; 4 (21): 546559

The scaling hypothesis: Simplifying the prediction of network performance using scaleddown simulations
ASSOC COMPUTING MACHINERY. 2003: 3540
View details for Web of Science ID 000183263400006

Energyefficient packet transmission over a wireless link
IEEEACM TRANSACTIONS ON NETWORKING
2002; 10 (4): 487499
View details for DOI 10.1109/TNET.2002.801419
View details for Web of Science ID 000177635200005

Efficient randomized webcache replacement schemes using samples from past eviction times
IEEEACM TRANSACTIONS ON NETWORKING
2002; 10 (4): 441454
View details for DOI 10.1109/TNET.2002.801414
View details for Web of Science ID 000177635200001

An implementable parallel scheduler for inputqueued switches
IEEE MICRO
2002; 22 (1): 1925
View details for Web of Science ID 000173795900006
 On Parisi’s conjecture for the random assignment problem 2002
 Flow tablebased design to approximate fairness 2002
 A study of the applicability of a scaling hypothesis 2002
 An implementable parallel scheduler for input queued switches IEEE Micro 2002; 1 (22): 1925
 Towards simple, highperformance schedulers for high aggregate bandwidth switches 2002

Efficient randomized algorithms for inputqueued switch scheduling
IEEE MICRO
2002; 22 (1): 1018
View details for Web of Science ID 000173795900005

Maintaining statistics counters in router line cards
IEEE MICRO
2002; 22 (1): 7681
View details for Web of Science ID 000173795900012

Approximate fairness through differential dropping  (summary)
COMPUTER COMMUNICATION REVIEW
2002; 32 (1): 7272
View details for Web of Science ID 000174890100021

Approximate fair dropping for variablelength packets
IEEE MICRO
2001; 21 (1): 4856
View details for Web of Science ID 000166764900018
 Smoothing out focused demand for network resources 2001
 Packet dropping schemes, some examples and analysis 2001
 An efficient randomized algorithm for inputqueued switch scheduling 2001
 An implementable parallel scheduler for inputqueued switches 2001
 Approximate fair dropping for variable length packets by invitation, IEEE Micro, 2001; 1 (21): 4856
 The randomness in randomized load balancing 2001
 Entropy and the timing capacity of discrete queues 2001

The synchronization of Poisson processes and queueing networks with service and synchronization nodes
ADVANCES IN APPLIED PROBABILITY
2000; 32 (3): 824843
View details for Web of Science ID 000165116500014
 A randomized cache replacement approximating LRU 2000
 An approximate fair dropping scheme for variable length packets 2000
 CHOKe — a stateless active queue management scheme for approximating fair bandwidth allocation 2000
 Nearoptimal routing lookups with bounded worst case performance 2000
 The throughput of data switches with and without speedup 2000

On the speedup required for combined input and outputqueued switching
AUTOMATICA
1999; 35 (12): 19091920
View details for Web of Science ID 000083587700004

Induction of experimental autoimmune Graves' disease in BALB/c mice
JOURNAL OF IMMUNOLOGY
1999; 163 (9): 51575164
Abstract
We immunized BALB/c mice with M12 cells (H2d) expressing either mouse (mM12 cells) or human thyrotropin receptor (TSHR) (hM12 cells). Immunized mice developed autoantibodies to native TSHR by day 90 and, by day 180, showed considerable stimulatory Ab activity as measured by their ability to enhance cAMP production (ranging from 6. 52 to 20.83 pmol/ml in different treatment groups relative to 1.83 pmol/ml for controls) by TSHRexpressing Chinese hamster ovary cells. These mice developed severe hyperthyroidism with significant elevations in both tetraiodothyronine and triiodothyronine hormones. Tetraiodothyronine levels in different experimental groups ranged from a mean of 8.6612.4 microg/dl, relative to 4.8 microg/dl in controls. Similarly, mean triiodothyronine values ranged from 156.18 to 195.13 ng/dl, relative to 34.99 ng/dl for controls. Next, we immunized BALB/c mice with a soluble extracellular domain of human TSHR (TBP), or TBP expressed on human embryonic kidney cells (293 cells) (293TBP cells). These mice showed severe hyperthyroidism in a manner very similar to that described above for mice immunized with the mouse TSHR or human TSHR, and exhibited significant weight loss, with average weight for treatment groups ranging from 20.6 to 21.67 g, while controls weighed 24.2 g. Early after onset of the disease, histopathological examination of thyroids showed enlargement of colloids and thinning of epithelial cells without inflammation. However, later during disease, focal necrosis and lymphocytic infiltration were apparent. Our results showed that conformationally intact ectodomain of TSHR is sufficient for disease induction. Availability of a reproducible model in which 100% of the animals develop disease should facilitate studies aimed at understanding the molecular pathogenesis of Graves' disease.
View details for Web of Science ID 000083256000066
View details for PubMedID 10528222

Matching output queueing with a combined input/outputqueued switch
IEEEINST ELECTRICAL ELECTRONICS ENGINEERS INC. 1999: 10301039
View details for Web of Science ID 000081210100003
 The entropies of queue arrivals and queue departures 1999
 Invariant rate functions for discrete time queues 1999
 CHOKe — A stateless mechanism for providing quality of service in the Internet 1999
 On the speedup required for combined input and output queued switching invited paper, Automatica 1999; 12 (35): 19091920
 Stochastic analysis of stable marriages in combined input output queued switches 1999
 Entropy and the Shannon capacity of queueing systems 1999
 A twobit scheme for routing lookup 1999
 On the synchronization of Poisson processes and queueing networks with service and synchronization nodes Stanford University Computer Science Department Technical Report, STANCSTR981613 1998
 A large deviations characterization of the fixed point of a ·/G/1 queue 1998

Multicast scheduling for inputqueued switches
IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
1997; 15 (5): 855866
View details for Web of Science ID A1997XF29000009
 Matching output queueing with combined input and output queueing 1997
 The Cesaro limit of departures from certain ·/GI/1 queueing tandems Stochastic Networks: Theory and Applications edited by Kelly, F., P., Zachary, S., Ziedins, I. Royal Statistical Society Lecture Note Series, Clarendon Press, Oxford. 1996: 309322
 Tetris models for multicast switches 1996
 Convergence of departures in tandem networks of ·/GI/1 queues Probability in the Engineering and Informational Sciences 1996; 10: 487500
 The entropy and delay of processes in ATM networks 1995
 IMA Volumes in Mathematics and its Applications edited by Kelly, F., Williams, R. Springer Verlag, New York. 1995
 Entropy methods for high speed communications 1995
 On the weak convergence of departures from an infinite series of ·/M/1 queues Annals of Applied Probability 1995; 1 (5): 121127
 Designing a multicast switch scheduler 1995
 Convergence of departures from an infinite sequence of queues 1994
 The asymptotics of traffic processes in large queueing networks 1994
 On infinite queueing tandems Systems & Control Letters 1994; 4 (23): 305314
 Estimation of wind profile from laser beam propagation distortion 1992