Ramtin Rabiee

Umeå University | UMU · Department of Applied Physics and Electronics

Intelligent transportation system significantly relies on accurate positioning information of land vehicles for both safety and non-safety related applications, such as hard-braking ahead warning and red-light violation warning. However, existing Global Navigation Satellite System (GNSS) based solutions suffer from positioning performance degradati...

The advancements in sensor and communication technologies drive the rapid developments in the applications of occupancy and indoor environmental monitoring in buildings. Currently, the installation standards for sensors are scarce and the recommendations for sensor positionings are very general. However, inadequate sensor positioning might diminish...

Knowledge about the indoor occupancy is one of the important sources of information to design smart buildings. In some applications, the number of occupants in each zone is required. However, there are many challenges such as user privacy, communication limit, and sensor’s computational capability in development of the occupancy monitoring systems....

Environmental sustainability in academic buildings can be improved with management interventions such as improving space use efficiency supported by large data from the Internet of Things (IoT). Due to the potentials, the interest in the use of IoT tools for facility management is high among universities. However, empirical studies on this topic ar...

Building in higher education institutions (HEIs) are characterized as energy intensive Experience from practice showing large discrepancies between predicted and actual energy performance. The deviation can sometimes reach 100%. Explanations often originate from occupant’s behaviour along with building operation. IoT-based smart tools can provide e...

Vehicle self-positioning is of significant importance for intelligent transportation applications. However, accurate positioning (e.g., with lane-level accuracy) is very difficult to obtain due to the lack of measurements with high confidence, especially in an environment without full access to a global navigation satellite system (GNSS). In this p...

The quality of energy detector is quite challenging when the system parameters are not stable. On the other hand, in a cognitive radio network, primary users are licensed to use the desired radio spectrum band(s) and the throughput of the primary network has the highest priority to be kept satisfied. Therefore, it is quite important to secure the q...

Status changing of the primary user and the number of secondary users (SUs) are crucial issues for designing a reliable cognitive radio network. In this paper, a medium-traffic primary network is assumed when secondary users are stochastically distributed over an area around a secondary base station. By using cooperative spectrum sensing over Rayle...

Cognitive radio (CR) has been viewed as a promising solution to spectrum scarcity. In order to design a reliable CR system, many improvements have been proposed to enhance spectrum sensing performance of secondary users (SUs) in a CR network (CRN). Sensing reliability and transmission throughput of SUs are two important performance criteria, which...

By considering spectrum-sensing periods of secondary users in a cognitive radio network besides the traffic rate of primary users, it is probable to have a medium-traffic primary network in which the primary user may change its state, either idle or active, at most once during the time period of spectrum sensing, resulting in performance degradatio...

In a medium-traffic primary network, primary user (PU) changes its state (either idle or active) at most once during a frame period, resulting in the performance degradation of the secondary network. In this work, we evaluate the performance of the proposed improved double-threshold energy detector (IDED) in the case of cooperative spectrum sensing...

The status of a primary user (PU) within sensing time is one of the important parameters, which is considered to be fixed in many studies of spectrum sensing in cognitive radio networks. In this paper, we consider a medium traffic of a primary network, in which the PU changes its state (either idle or active) at most once during the sensing period...

For a cognitive radio network (CRN), there are many studies on transmission throughput of secondary users (SUs) with a fixed status for the primary user (PU) during the test period. In this paper, we consider a medium-traffic primary network, in which the PU changes its state (either idle or active) at most once during the frame time. This instabil...

Cognitive radio (CR) has been proposed as a promising solution to overcome the spectrum scarcity problem. Many works have been reported to improve spectrum sensing performance of secondary users (SUs) as an essential step to design a CR network (CRN). Spectrum sensing optimization is able to improve spectral efficiency and protect a primary user (P...