Zhaleh Sadreddini

PSO-optimized Instant Overbooking Framework for cognitive radio networks

Nowadays, the emerging wireless communication technologies cause rapid growth in radio spectrum usage. However, the radio spectrum is a limited resource and has almost been fully assigned by the current network operators (NOs). Although numerous studies have been accomplished on the spectrum management, there are rare evolutionary techniques dealing with booking spectrum on cognitive radio. Instant Overbooking Framework for Cognitive Radio networks (IOFCR) is used to maximize both spectrum utilization and the revenue of NOs under several over-booking and pricing policies. In such a network, when a primary user (PU) activity is sensed, the control of which requesting secondary users (SUs) can be denied and which Active SUs can be ejected is managed by IOFCR. In this paper, the Particle Swarm Optimization (PSO) algorithm is applied into the IOFCR to find optimal values of the over-booking price and the Compensation Cost (CC) ratio to optimize revenue and achieve high performance.

Dynamic Resource Sharing in 5G with LSA: Criteria-Based Management Framework

Owing to a steadily increasing demand for efficient spectrum utilization as part of the fifth-generation (5G) cellular concept, it becomes crucial to revise the existing radio spectrum management techniques and provide more flexible solutions for the corresponding challenges. A new wave of spectrum policy reforms can thus be envisaged by producing a paradigm shift from static to dynamic orchestration of shared resources. The emerging Licensed Shared Access (LSA) regulatory framework enables flexible spectrum sharing between a limited number of users that access the same frequency bands, while guaranteeing better interference mitigation. In this work, an advanced user satisfaction-aware spectrum management strategy for dynamic LSA management in 5G networks is proposed to balance both the connected user satisfaction and the Mobile Network Operator (MNO) resource utilization. The approach is based on the MNO decision policy that combines both pricing and rejection rules in the implemented processes. Our study offers a classification built over several types of users, different corresponding attributes, and a number of MNO’s decision scenarios. Our investigations are built on Criteria-Based Resource Management (CBRM) framework, which has been specifically designed to facilitate dynamic LSA management in 5G mobile networks. To verify the proposed model, the results (spectrum utilization, estimated Secondary User price for the future connection, and user selection methodology in case of user rejection process) are validated numerically as we yield important conclusions on the applicability of our approach, which may offer valuable guidelines for efficient radio spectrum management in highly dynamic and heterogeneous 5G environments.

Multi-path route discovery algorithm for cognitive radio ad hoc networks using algebraic connectivity

Cognitive Radio Technology has brought new insights to the problems of spectrum scarcity and inefficiency, in which spectrum holes are opportunistically accessed when the licensed users (primary users) are not using the frequencies that are assigned to those users. In this paper, we propose a multi-path route discovery algorithm for cognitive radio ad hoc networks (CRAHN) using algebraic connectivity. The employed routing mechanism takes into account the impact of the primary users on the non-licensed users (secondary users) in a way that the secondary users choose the paths which are less affected by the non-licensed users. With regard to proposed route discovery algorithm, data traffic congestions are tried to be avoided in the secondary network by reducing the number of all possible paths from source to destination. The results show that the devised method overcomes the technique of the route request (RREQ) message flooding between a source and a destination.

Pre-reservation based spectrum allocation for cognitive radio network

Studies on the current usage of the radio spectrum by several agencies have already revealed that a large fraction of the radio spectrum is inadequately utilized. This basic finding has led to numerous research initiatives. Cognitive radio technology is one of the key candidate technologies to solve the problems of spectrum scarcity and low spectrum utilization. However, random behavior of the primary user (PU) appears to be an enormous challenge. In this paper, a Pre-reservation based spectrum allocation method for cognitive radio network is proposed to apply a PU behavior aware joint spectrum band (SB) selection and allocation scheme. In the first step, the SB is observed in terms of PU usage statistics whereas in the second phase, a network operator (NO) using a spectrum allocation scheme is employed to allocate SBs among secondary users (SUs). We also introduce the concept of reservation and exchange functionality under the priority serving strategy in a time-varying framing process. Simulation results show that the proposed scheme outperforms existing schemes in terms of the spectrum utilization and network revenue. In addition, it helps NO to manage the spectrum on a planned basis with a systematical spectrum reservation management where the NO has the status of time slots. Moreover, SUs have an opportunity to reserve or instantly request a SB that maximizes the SUs satisfaction in terms of quality of experience.

Modeling of spectrum handoff in 3GPP LTE-A indoor deployment

The lack of available radio spectrum and inefficiency in its usage necessitate a new communication paradigm requiring to exploit the existing spectrum opportunistically. One of the perspective spectrum sharing methods, which is currently under a heavy investigation by academia and industry as well across whole Europe, is called Licensed Shared Access (LSA). This novel technology allows for controlled sharing of spectrum between an original owner (primary user, incumbent) and a licensee (secondary user), such as the mobile network operators (MNOs), which coexist geographically. Despite certain benefits, there are still several issues to be solved before the LSA framework will be implemented in commercial infrastructure. One of them is the need to move secondary users (SUs) from the rented LSA band whenever the incumbent needs it. The potential solution for this problem is represented by spectrum handoff, which aims to help SUs to vacate the occupied licensed spectrum and find suitable network resources to resume the unfinished transmissions somewhere else. Inspired by this, we propose a decision making model considering several SUs attributes (RSSI, RSRP, RSRQ, SINR) in order to efficiently implement the handoff procedure and treat SUs to maximize total service time, spectrum utilization and SUs satisfaction. As an input for our simulation model, we have used the set of measurements performed in real 3GPP LTE-A indoor cellular system located at Brno University of Technology, Czech republic. Our achieved simulation results evaluate the spectrum utilization of three LTE cells and provide the total service time for each active SU, while different values of primary users activity ratio are considered for each cell.

Performance analysis of dynamic spectrum management in cognitive radio networks

With the development of new applications, the number of users in telecommunication networks is increasing considerably. Cognitive radio (CR) is a promising solution to manage radio resources by opening up the underutilized parts of the licensed spectrum for secondary reuse. A proper radio resource management (RSM) policy should be implemented to improve overall network performance with paying regard to both network operator (NO) and user satisfaction. Instant Overbooking Framework for Cognitive Radio Network (IOFCR) is provided in order to pave the way for better utilization of radio resources in the network. In this study, performance of dynamic switch IOFCR is evaluated in peak/off-peak hours. Simulation results show the overbooking limit of each IOFCR overbooking policies in both peak/off-peak hours. Based on the dynamic switch system, NO tradeoffs cost-performance of IOFCR via different overbooking thresholds. Simulation results show that the selecting appropriate overbooking policy leads to decrease the number of eliminated active secondary users (ASUs) then increase network revenue as NO pays reasonable compensation cost (CC) for eliminated ASUs.

Performance analysis of the dynamic switch system based on user activity in cognitive radio network

According to the peak hours of the day, the number of sensed primary users (PUs) and also requesting secondary users (RSUs) will be dramatically increased. Since the radio spectrum is a limited resource, efficient spectrum management techniques on cognitive radio is necessary to manage all PUs, active secondary users (ASUs) and RSUs where all three types of the users have unknown activity ratios. Instant Overbooking Framework for Cognitive Radio Networks (IOFCR) is used to maximize both spectrum utilization and the network revenue under several spectrum management policies. In this paper, dynamic switch system based on user activity is designed for IOFCR. Accordingly, IOFCR automatically switches to the convenient policy to minimize the elapsed time and to get high spectrum utilization with minimal policy complexity in peak hours. Simulation results show that a considerable amount of improvement is achieved through taking user activities into account.

A distance measurement method using single camera for indoor environments

A distance measurement method for a single-camera condition is proposed. The aim is to implement a way to find the distance of an object in front of the imaging system in indoor environment. In this method, the first step is to extract the appropriate vertical floor line from the snapshots sequence. Moreover, the line passing through the base side of the object is found simultaneously with the floor line. Then, the part of the floor line starting from this point is measured in pixels, by taking the intersection point of these lines, and converted to distance between the camera and the object. The proposed method is applicable for flat indoor buildings with regular lines on the floor, while many buildings are in such a situation. Experimental results are carried out by using MATLAB to estimate the measured distance by the proposed method.