The Effect of Carrier Mismatch on RSS Ranging and Localization

Indoor localization is a core technology for many position-aware applications. This is often based on the mea-surement of the signal strength at the receiver end, which is available for many commercial radio protocols without additional costs, e.g., for WiFi, Bluetooth or Zigbee. However, a major limitation with received signal strength (RSS)-based methods are high inaccuracies resulting mainly from physical propagation effects. But these effects are not the only cause for erroneous position estimates. In this paper we first present a RSS measure-ment system and localization setup based on Software Defined Radio (SDR)s, which reduces protocol-specific influences such as transmit power management. In addition, the RSS value can be measured with a much higher resolution and sampling rate, which gives more headroom to analyze its statistical and temporal properties. The measurement data is then evaluated to get an insight on the errors and disturbances commonly associated with RSS localization schemes. This allows us to identify a problem in the basic way RSS-based localization methods process the measurement data, which could be partially responsible for the high variance typically associated with RSS measurements and the elusive fast fading effect. The goal of this work is to investigate some fundamental aspects of RSS localization to better understand the limitations of the technology.