Jan C.W. van Ommeren

Energy consumption in coded queues for wireless information exchange

We show the close relation between network coding and queuing networks with negative and positive customers. Moreover, we develop Markov reward error bounding techniques for networks with negative and positive customers. We obtain bounds on the energy consumption in a wireless information exchange setting using network coding.

Delay in a tandem queueing model with mobile queues: An analytical approximation

In this paper, we analyze the end-to-end delay performance of a tandem queueing system with mobile queues. Due to state-space explosion, there is no hope for a numerical exact analysis for the joint-queue-length distribution. For this reason, we present an analytical approximation that is based on queue-length analysis. Through extensive numerical validation, we find that the queue-length approximation exhibits excellent performance for light traffic load.

A two-echelon spare parts network with lateral and emergency shipments: A product-form approximation

We consider a single-item, two-echelon spare parts inventory model for repairable parts for capital goods with high down time costs. The inventory system consists of a central warehouse and multiple local warehouses, from where customers are served, and a central repair facility at an external supplier. When a part fails at a customer, his request for a ready-for-use part is immediately fullled by his local warehouse if it has a part on stock. At the same time, the failed part is sent to the central repair facility for repair. If the local warehouse is out of stock, then, via an emergency shipment, a ready-for-use part is sent from the central warehouse if it has a part on stock. Otherwise, it is sent via a lateral transshipment from another local warehouse or the external supplier. We assume Poisson demand processes, generally distributed leadtimes for replenishments, repairs, and emergency shipments, and a base-stock policy for the inventory control. Because our inventory system is too complex to solve for a steady-state distribution in closed form, we approximate it by a network of Erlang loss queues with so-called hierarchical jump-over blocking. We show that this network has a steady-state distribution in product-form. Further, this steady-state distribution and several relevant performance measures only depend on the distributions for the repair and replenishment lead times via their means (i.e., they are insensitive for the underlying probability distributions). The steady-state distribution in product-form enables an ecient heuristic for the optimization of base-stock levels, resulting in good approximations of the optimal costs.

Average Case Analysis of the MST-heuristic for the Power Assignment Problem: Special Cases

We present an average case analysis of the minimum spanning tree heuristic for the power assignment problem. The worst-case approximation ratio of this heuristic is 2. We have the following results: (a) In the one-dimension\-al case, with uniform

Energy-delay tradeoff in wireless network coding

\left[ 0,1 \right]

Threshold queueing describes the fundamental diagram of uninterrupted traffic

-distributed distances, the expected approximation ratio is bounded above by

Linear programming error bounds for random walks in the quarter-plane

2 - 2/(\myp+2)

A transient analysis of polling systems operating under exponential time-limited service disciplines

, where

A Stochastic model for inter-terminal container transportation

\myp

A successive censoring algorithm for a system of connected QBD-processes

denotes the distance power gradient. (b) For the complete graph, with uniform