Clock skew invariant beamforming: for a wireless acoustic sensor network

This thesis is focused on Wireless Acoustic Sensor Networks (WASNs) used for beamforming in a speech enhancement task. Since each node in a WASN has its own clock, clock offsets and clock skews between the nodes are inevitable. Clock offsets and clock skew can be detrimental to the beamformer performance. In this thesis we focus on the effect of...

Wireless Clock Synchronisation for UWB Positioning

An Indoor Positioning System (IPS) is being developed at TOPIC Embed- ded Systems to track equipment in hospitals. The system should prevent the loss of equipment en make procedures more efficient. The IPS will con- sist of anchors and tags. Anchors are the radios that form an infrastructure in the building to localise tags that are placed on...

A Wireless Sensor Network for Machine Dynamics Performance Monitoring

The availability of photolithography machines is key in the semiconductor industry, as downtime generally incurs in immense economic loss. Time to market is also very important for suppliers of photolithography systems, such as ASML. Photolithography machines include numerous measurement systems that are frequently used for qualification and...

Joint Ranging and Clock Synchronization for Dense Heterogeneous IoT Networks

Synchronization and ranging in internet of things (IoT) networks are challenging due to the narrowband nature of signals used for communication between IoT nodes. Recently, several estimators for range estimation using phase difference of arrival (PDoA) measurements of narrowband signals have been proposed. However, these estimators are based...

A practical clock synchronization algorithm for UWB positioning systems

A clock synchronization scheme is crucial for obtaining accuracy in time-based positioning systems. Existing clock synchronization schemes are mostly based on a simplified linear clock model, which unfortunately have a poor long-term synchronization accuracy. Assuming a two-way time transfer protocol, we propose a novel clock synchronization...

Sparse Sensing for Statistical Inference: Theory, Algorithms, and Applications

In today's society, we are flooded with massive volumes of data in the order of a billion gigabytes on a daily basis from pervasive sensors. It is becoming increasingly challenging to locally store and transport the acquired data to a central location for signal/data processing (i.e., for inference). To alleviate these problems, it is evident...

Scalable Network Based Clock Synchronization for Digital PET System

Typically in synchronous digital systems time-based tasks are synchronized using hard-wired clock distribution networks. However in the growing application of large (wireless) sensor networks it is not always feasible to connect each sensor node to a hard-wired clock distribution network. Generally in such systems the sensor nodes are only...

Joint non-linear ranging and affine synchronization basis for a network of mobile nodes

Synchronization and localization are critical challenges for the coherent functioning of a wireless network of mobile nodes. In this paper, a novel joint non-linear range and affine time model is presented based on two way time stamp exchanges, extending an existing affine time-range model. For a pair of nodes, a closed form pairwise least...

Time Synchronization in Wireless Sensor Networks

Accurate time synchronization is crucial for many applications of Wireless Sensor Networks. Extensive research is performed on this topic, however, there are some aspects of time synchronization which still require attention. In this thesis we investigate aspects of the network which influence the accuracy of packed based time synchronization in...