Positioning in Wireless Communications Systems

Chapter 1Introduction

The determination of position is an art that has fascinated scientists for centuries. First positioning methods were probably developed several millennia ago when people realized the necessity of knowing their position for systematic travel. Orientation at natural landmarks such as mountains, rivers, or coastlines are straightforward methods for that purpose. Early man made landmarks were trails and ways that were often built for trading, for example, the famous Silk Road, which has its origins around 500 B.C., and connected Europe and Eastern Asia. Other man made landmarks are lighthouses. They provide orientation in monotonous environments even at night, for example, for ships relatively close to the coastline. On the high seas, however, landmarks are missing. Keeping track of a journey by measuring direction and velocity, called the dead reckoning method, was the straightforward approach used by early ocean navigators. Celestial navigation is another method that utilizes well-known objects as position references. Measuring the angle of the pole star above the horizon directly provides the latitude. The major problem for a long time has been the determination of the longitude directly related to the exact measurement of time due to the Earth's rotation. As the Earth rotates around each day, a deviation of 4 s in time keeping results in a position error ...