Publications (29)
Transition time asymptotics of queue-based activation protocols in random-access networks
Sem Borst, Frank den Hollander, Francesca R. Nardi +1
We consider networks where each node represents a server with a queue. An active node deactivates at unit rate. An inactive node activates at a rate that depends on its queue lengt…
Induced idleness leads to deterministic heavy traffic limits for queue-based random-access algorithms
Eyal Castiel, Sem Borst, Laurent Miclo +2
We examine a queue-based random-access algorithm where activation and deactivation rates are adapted as functions of queue lengths. We establish its heavy traffic behavior on a com…
Lingering Issues in Distributed Scheduling
Florian Simatos, Niek Bouman, Sem Borst
Recent advances have resulted in queue-based algorithms for medium access control which operate in a distributed fashion, and yet achieve the optimal throughput performance of cent…
Optimal Hyper-Scalable Load Balancing with a Strict Queue Limit
Mark van der Boor, Sem Borst, Johan van Leeuwaarden
Load balancing plays a critical role in efficiently dispatching jobs in parallel-server systems such as cloud networks and data centers. A fundamental challenge in the design of lo…
Stability of a Stochastic Ring Network
Jaap Storm, Wouter Kager, Michel Mandjes +1
In this paper we establish a necessary and sufficient stability condition for a stochastic ring network. Such networks naturally appear in a variety of applications within communic…
Redundancy scheduling with scaled Bernoulli service requirements
Youri Raaijmakers, Sem Borst, Onno Boxma
Redundancy scheduling has emerged as a powerful strategy for improving response times in parallel-server systems. The key feature in redundancy scheduling is replication of a job u…
Queue-Based Random-Access Algorithms: Fluid Limits and Stability Issues
Javad Ghaderi, Sem Borst, Phil Whiting
We use fluid limits to explore the (in)stability properties of wireless networks with queue-based random-access algorithms. Queue-based random-access schemes are simple and inheren…
Scaling Laws for Maximum Coloring of Random Geometric Graphs
Sem Borst, Milan BradonjiÄ
We examine maximum vertex coloring of random geometric graphs, in an arbitrary but fixed dimension, with a constant number of colors. Since this problem is neither scale-invariant…
Delay versus Stickiness Violation Trade-offs for Load Balancing in Large-Scale Data Centers
Qingkai Liang, Sem Borst
Most load balancing techniques implemented in current data centers tend to rely on a mapping from packets to server IP addresses through a hash value calculated from the flow five-…
Threshold-based rerouting and replication for resolving job-server affinity relations
Youri Raaijmakers, Sem Borst, Onno Boxma
We consider a system with several job types and two parallel server pools. Within the pools the servers are homogeneous, but across pools possibly not in the sense that the service…
Optimal Service Elasticity in Large-Scale Distributed Systems
Debankur Mukherjee, Souvik Dhara, Sem Borst +1
A fundamental challenge in large-scale cloud networks and data centers is to achieve highly efficient server utilization and limit energy consumption, while providing excellent use…
Delay Performance and Mixing Times in Random-Access Networks
Niek Bouman, Sem Borst, Johan van Leeuwaarden
We explore the achievable delay performance in wireless random-access networks. While relatively simple and inherently distributed in nature, suitably designed queue-based random-a…
Subexponential asymptotics of hybrid fluid and ruin models
Bert Zwart, Sem Borst, Krzystof Debicki
We investigate the tail asymptotics of the supremum of X(t)+Y(t)-ct, where X={X(t),t\geq 0} and Y={Y(t),t\geq 0} are two independent stochastic processes. We assume that the proces…
Power-of-two sampling in redundancy systems: the impact of assignment constraints
Ellen Cardinaels, Sem Borst, Johan S. H. van Leeuwaarden
A classical sampling strategy for load balancing policies is power-of-two, where any server pair is sampled with equal probability. This does not cover practical settings with assi…
Stability of Redundancy Systems with Processor Sharing
Youri Raaijmakers, Sem Borst, Onno Boxma
We investigate the stability condition for redundancy-d systems where each of the servers follows a processor-sharing (PS) discipline. We allow for generally distributed job sizes,…
Fork-join and redundancy systems with heavy-tailed job sizes
Youri Raaijmakers, Sem Borst, Onno Boxma
We investigate the tail asymptotics of the response time distribution for the cancel-on-start (c.o.s.) and cancel-on-completion (c.o.c.) variants of redundancy- scheduling and t…
Exact asymptotics for fluid queues fed by multiple heavy-tailed on-off flows
Bert Zwart, Sem Borst, Michel Mandjes
We consider a fluid queue fed by multiple On-Off flows with heavy-tailed (regularly varying) On periods. Under fairly mild assumptions, we prove that the workload distribution is a…
Stability of parallel queueing systems with coupled service rates
Sem Borst, Matthieu Jonckheere, Lasse Leskelä
This paper considers a parallel system of queues fed by independent arrival streams, where the service rate of each queue depends on the number of customers in all of the queues. N…
Multi-dimensional state space collapse in non-complete resource pooling scenarios
Ellen Cardinaels, Sem Borst, Johan S. H. van Leeuwaarden
The present paper establishes an explicit multi-dimensional state space collapse (SSC) for parallel-processing systems with arbitrary compatibility constraints between servers and…
Hyper-Scalable JSQ with Sparse Feedback
Mark van der Boor, Sem Borst, Johan van Leeuwaarden
Load balancing algorithms play a vital role in enhancing performance in data centers and cloud networks. Due to the massive size of these systems, scalability challenges, and espec…
Deep Reinforcement Learning for Intelligent Transportation Systems
Xiao-Yang Liu, Zihan Ding, Sem Borst +1
Intelligent Transportation Systems (ITSs) are envisioned to play a critical role in improving traffic flow and reducing congestion, which is a pervasive issue impacting urban areas…
A stochastic network with mobile users in heavy traffic
Sem Borst, Florian Simatos
We consider a stochastic network with mobile users in a heavy-traffic regime. We derive the scaling limit of the multi-dimensional queue length process and prove a form of spatial…
Stability of Random Admissible-Set Scheduling in Spatially Continuous Wireless Systems
Niek Bouman, Sem Borst, Johan van Leeuwaarden
We examine the stability of wireless networks whose users are distributed over a compact space. A subset of users is called {\it admissible} when their simultaneous activity obeys…
Achievable Stability in Redundancy Systems
Youri Raaijmakers, Sem Borst
We consider a system with parallel servers where incoming jobs are immediately replicated to, say, servers. Each of the servers has its own queue and follows a FCFS dis…
Deep Reinforcement Learning for Traffic Light Control in Intelligent Transportation Systems
Ming Zhu, Xiao-Yang Liu, Sem Borst +1
Smart traffic lights in intelligent transportation systems (ITSs) are envisioned to greatly increase traffic efficiency and reduce congestion. Deep reinforcement learning (DRL) is…
Heavy-Traffic Universality of Redundancy Systems with Assignment Constraints
Ellen Cardinaels, Sem Borst, Johan S. H. van Leeuwaarden
Service systems often face task-server assignment-constraints due to skill-based routing or geographical conditions. Redundancy scheduling responds to this limited flexibility by r…
Load Balancing in Large-Scale Systems with Multiple Dispatchers
Mark van der Boor, Sem Borst, Johan van Leeuwaarden
Load balancing algorithms play a crucial role in delivering robust application performance in data centers and cloud networks. Recently, strong interest has emerged in Join-the-Idl…
Heavy Loads and Heavy Tails
Sem Borst
The present paper is concerned with the stationary workload of queues with heavy-tailed (regularly varying) characteristics. We adopt a transform perspective to illuminate a close…
Crossover times in bipartite networks with activity constraints and time-varying switching rates
Sem Borst, Frank den Hollander, Francesca Nardi +1
In this paper we study the performance of a bipartite network in which customers arrive at the nodes of the network, but not all nodes are able to serve their customers at all time…