An Indoor Positioning System using Cognitive Radio

Background

With the introduction of the new Galileo and Compass systems and the modernization of the GPS and Glonass systems, we can expect new satellites, signals and frequencies to emerge in the coming years. They will open the door for countless applications in a wide range of fields, including telecommunications. Soon, mobile phones will be able to use navigation systems to determine a person’s position inside a building—something that is currently very difficult.

Challenges

GPS navigation signals cannot be captured within buildings because the signal strength is too weak. It is almost impossible to acquire and track the signals autonomously because of signal attenuation caused by various materials (Table 1).

Table 1 Signal attenuation caused by different materials [1]

Figure 1 Indoor positioning challenges

Objectives

The objectives of this research project are to:

• Develop new methods and architectures for robust high-sensitivity GNSS receivers able to overcome interference
• Create new algorithms to be integrated into hybrid GNSS receivers that can work inside buildings thanks to the use of:
  • All GNSS signals
  • A collective-detection approach for acquiring satellite signals
  • New cognitive-radio concepts

The final objective is to design a new high-sensitivity cognitive receiver that can effectively capture the new GNSS signals.

Methodology

This methodology includes using cognitive radio technology and software-defined radio on a platform that includes receivers for the four main navigation systems: GPS, Glonass, Galileo and Compass. For Benmammar [2], “the term ‘cognitive radio’ is used to describe a system with the ability to sense and recognize its context of use, in order to enable it to adjust its radio operating parameters dynamically and autonomously and learn from the results of its actions and its environmental setting operation”

In their article “Software-defined radio to support aviation efficiency,” published on Substance ÉTS, William Coady and René Jr. Landry define software-defined radio as “systems that can be used to transmit and/or receive radio signals. But in contrast to the functions of dedicated radio equipment, those of software-defined radio systems are programmed in software written by the user. Thus the same radio system can be used to perform multiple tasks. Moreover, it can be reprogrammed at any time.” [3]

Figure 2 Software-defined radio design, source [Img1]

Optimizing the receiver will make it possible to increase its sensitivity by at least 6 dB above current industry levels while maintaining precision in positioning. Cognitive radio will be used to ensure that the receiver operates intelligently and autonomously (choosing the best satellites to process) and makes optimal use of available resources (Figure 3).

Figure 3 Overview of the research proposal

Cognitive Radio

Cognitive radio (CR) technology has been successfully applied in the telecommunications field and recently included in satellite navigation systems. Table 2 indicates how cognitive radio technology offers more flexibility than software-developed radio (SDR). For this reason, we want to include it in the platform used at the LASSENA Laboratory. In fact, by simply adding an extra cognitive layer to the whole SDR portion already in use, we hope to create a system that is both more flexible and intelligent. Moreover, the specific CR properties seen in Table 2 (data gathering on channel conditions, learning about the environment and experimenting with different settings) are essential considerations in the proposed receiver design.

Table 2 Comparison of SDR and CR radio technologies [4]

To Be Continued

The article A Cognitive Receiver for Indoor Positioning will present the High Sensitivity Cognitive GNSS Receiver – HS-CGR, the experiments conducted and the conclusion.

This project is carried out between the École de technologie supérieure (ÉTS) and the Institut supérieur de l’aéronautique et de l’espace (ISAE) in Toulouse, France.

Research Article

An article on the collective detection portion entitled “A New Method of Collective Acquisition of Multiple GNSS Satellite Signals in Challenging Environments” was presented at the Navitec Conference, held December 3 to 5, 2014 in Noordwijk, Netherlands.