## 1 Introduction  
In recent years, the interest in positioning and navigation has become increasingly important, as evidenced by systems and services developed using this technology. The use of GNSS receivers has increased considerably with the integration of GNSS chips in cellular phones and mobile devices that are used for potential applications in several domains, including location-based services (LBS) and intelligent transportation systems (ITS). Constantly increasing the number of GNSS signals and the diversity of navigation satellites is an important advantage, because it can improve the overall performance of the signal processing in a multi-constellation multi-frequency hybrid architecture. Traditional satellite navigation receivers must therefore be improved in order to allow the reception of all GNSS signals (current and future). These receivers must be designed to acquire as many satellite signals as possible from different constellations. The diversity and redundancy of GNSS measurements will further open the door to new developments and applications that are impossible to achieve with current receivers, which are designed for outdoor environments. Increasing the number of signals and the diversity of GNSS satellites provides significant benefits in many areas of application because it can improve the sensitivity performance of the signal processing in a hybrid architecture combining all GNSS signals. Overcoming the problem of positioning in hostile environments is best achieved using high sensitivity (HS) and robust receivers. Several techniques have been proposed to deal with this problem of receiving weak signals in urban environments. For indoor environments, many technologies have been proposed for localization purposes, because GNSS signals cannot be received with a sufficiently high signal-to-noise ratio [1]. Moreover, most techniques require a dedicated physical infrastructure. The Collective Detection (CD) technique is considered as a promising approach to perform GNSS signal reception and processing in harsh environments. It is a powerful method for acquiring highly attenuated satellite signals in constrained environments as it can process all visible satellites collectively taking advantage of the spatial correlation between GNSS signals as a vector acquisition scheme. The major advantage of CD as a collective acquisition method lies in its ability to use stronger signals to facilitate the acquisition of weaker ones and acquisition in harsh environments could be used directly for positioning without the need for standard tracking loops [2; 3; 4]. Indeed, the GNSS receiver antenna receives at least one strong signal which is then used to detect weak satellite signals in view, in a sort of multi-satellite collaborative processing. In the CD approach, the projection of the code phase onto the position/clock bias domain is done differentially with respect to the pseudorange measurements provided by a reference station with known position. As the number of mobile devices in use increases, applying the CD approach becomes easier since devices that are capable of receiving good satellite signals can assist others in difficulty [5]. The main objective of this paper is to propose an architecture of a smart high sensitivity GNSS receiver based on the CD approach. To design the architecture of an intelligent HS GNSS receiver, called as HS Smart GNSS Receiver (HS-SGR), we will begin by defining its basic operation according to the number of satellites detected as shown in Figure 1. If there are enough strong satellites (greater than or equal to 4) available to calculate the position of the receiver, a conventional sequential acquisition is carried out, otherwise, the CD process is used. Following this, the intelligence of the receiver must consider other parameters according to the acquisition method used to process the received satellite signals.