Andrijana Popovska Avramova

Application of Wireless Sensor Networks for Indoor Temperature Regulation

Wireless sensor networks take a major part in our everyday lives by enhancing systems for home automation, healthcare, temperature control, energy consumption monitoring, and so forth. In this paper we focus on a system used for temperature regulation for residential, educational, industrial, and commercial premises, and so forth. We propose a framework for indoor temperature regulation and optimization using wireless sensor networks based on ZigBee platform. This paper considers architectural design of the system, as well as implementation guidelines. The proposed system favors methods that provide energy savings by reducing the amount of data transmissions through the network. Furthermore, the framework explores techniques for localization, such that the location of the nodes can be used by algorithms that regulate temperature settings.

Towards future broadband public safety systems: Current issues and future directions

The vision of the Fifth generation (5G) of mobile communication is that it will be an umbrella for communications for various vertical industries that have different requirements for delay, data rates, reliability, availability, and security. 5G will not be a single technology - rather a convergence of not just new revolutionary technologies, but of the already existing, and evolving technologies as well. This paper analyses the impact of convergence and its importance to the evolution of critical communication systems, both with respect to the fundamental features of the public safety systems and the future broadband services that are becoming an integral part of the work of the first responders. This paper presents and discusses the recent standardization and research efforts in the area of public safety communication systems and indicates the technologies required to enable future broadband trusted communication system for safety and critical missions.

Radio access sharing strategies for multiple operators in cellular networks

Mobile operators are moving towards sharing network capacity in order to reduce capital and operational expenditures, while meeting the increasing demand for mobile broadband data services. Radio access network sharing is a promising technique that leads to reduced number of physical base station deployments (required for coverage enhancement), increased base station utilization, and reduced overall power consumption. Today, network sharing in the radio access part is passive and limited to cell sites. With the introduction of Cloud Radio Access Network and Software Defined Networking adoption to the radio access network, the possibility for sharing baseband processing and radio spectrum becomes an important aspect of network sharing. This paper investigates strategies for active sharing of radio access among multiple operators, and analyses the individual benefits depending on the sharing degree. The model used to assess the sharing strategies is based on multidimensional loss systems, and blocking probability is considered as performance metrics.

A framework for joint optical-wireless resource management in multi-RAT, heterogeneous mobile networks

Mobile networks are constantly evolving: new Radio Access Technologies (RATs) are being introduced, and backhaul architectures like Cloud-RAN (C-RAN) and distributed base stations are being proposed. Furthermore, small cells are being deployed to enhance network capacity. The end-users wish to be always connected to a high-quality service (high bit rates, low latency), thus causing a very complex network control task from an operators point of view. We thus propose a framework allowing joint overall network resource management. This scheme covers different types of network heterogeneity (multi-RAT, multi-layer, multi-architecture) by introducing a novel, hierarchical approach to network resource management. Self-Organizing Networks (SON) and cognitive network behaviors are covered as well as more traditional mobile network features. The framework is applicable to all phases of network operation like planning, deployment, operation, maintenance and therefore aids network operators in improving their business potential.

Cross layer scheduling algorithm for LTE downlink

The LTE standards is leading standard in the wireless broadband market. In order to accommodate the increased demand for mobile data services the radio interface in the LTE standard is enhanced with advanced technologies such as OFDMA (Orthogonal Frequency Division Multiple Access) and MIMO (multiple antenna) techniques. The Radio Resource Management at the base station plays major role in satisfying the users demand for high data rates and QoS. Resources for both downlink and uplink transmission need to be assigned such that the capacity, throughput, and cell edge performance are optimized. This paper evaluates a cross layer scheduling algorithm that aims at minimizing the resource utilization. The algorithm makes decisions regarding the channel conditions and the size of transmission buffers and different QoS demands. The simulation results show that the new algorithm improves the resource utilization as well as provides better guaranties for QoS.

Optimal Uplink Power Control for Dual Connected Users in LTE Heterogeneous Networks

In Dual Connectivity (DC), a User Equipment (UE) can be configured with two radio access nodes in order to aggregate the available resources at both nodes. As with dual connectivity each node has independent radio resource management, the maximum power allocation at the UE can be easily exceeded and the interference can be increased. Hence, the power distribution among the carriers needs to be optimized and has to minimize the required coordination among the nodes. In this paper we propose an optimal power allocation based on the load of the cells and cell effective interference. Additionally, we determine criteria for configuration of UEs with dual connectivity. The simulation results show performance improvement by the proposed algorithm with respect to the achieved user throughput. Performance gains (threefold gain in median user throughput) are evident in low as well as high loads in the cell.

Optimal Traffic Allocation for Multi-Stream Aggregation in Heterogeneous Networks

This paper investigates an optimal traffic rate allocation method for multi-stream aggregation over heterogeneous networks that deals with effective throughput aggregation over two or more heterogeneous links. The heterogeneity and the dynamics of radio is considered as an important factor for performance improvement by multi-stream aggregation. Therefore, in our model, the networks are represented by different queuing systems in order to indicate networks with opposite QoS provisioning, capacity and delay variations. Furthermore, services with different traffic characteristics in terms of QoS requirements are considered. The simulation results show the advantages of our model compared to traditional schemes for bandwidth aggregation.