The recent years WSNs have had a tremendous growth in interest. Many see the huge potential in this technology and the vast possibilities with small wireless autonomous nodes. WSN nodes have a few limitations like their small size and limited power consumption. A network might exist for years without any major maintenance, putting tight restrictions on available power. The price is also an important aspect, and cheap production technologies like CMOS is preferred.
The applications vary from cargo tracking to medical implants, and the requirements are as diverse. One requirement is present in almost all applications, and that is the need of localisation information. The localisation problem is yet to be solved for all applications. Almost all present systems rely on rigid infrastructure with anchor nodes or super nodes with extra capabilities. In this thesis a suggested algorithm for WSNs with no anchor nodes is presented, operating without any infrastructure. It is tested using different position estimation techniques.
An important part of all localisation algorithms is the data acquisition phase. This is to gather range, angle or connectivity information about the network. In WSNs angle information is hard to acquire, so connectivity and range information is the viable option. Existing range estimation techniques rely on highly inaccurate and imprecise RSS measurements. To improve the precision and accuracy of ranging a TDMC circuit was implemented. A digital real time circuit implemented i 90nm CMOS technology capable of measuring sub-10-picosecond time differences.