Irina Vermesan

Study of co-channel cross-layer interference for the downlink communication in femtocell networks

The paper is concerned with the study of the co-channel cross-layer interference which appears in evolved mobile networks, in which femtocell access points (FAPs) have been deployed. We will investigate the levels of interference for the downlink communication channel, in two cases: macrocell base station (MacroBS) interference at the femtocell user (FUE), and FAP interference at the macrocell user (MUE). The simulations are carried out in a combined indoor-outdoor environment. The performances of the network are evaluated according to the signal to interference plus noise ratio, measured on the downlink communication channel. The results of the study reveal the impact of the deployment of femtocells in existing mobile networks.

Multi antenna STBC transmission technique evaluation under IEEE 802.11n conditions

In this paper, the STBC (Space-Time Block Codes) transmission technique is used in order to evaluate the link availability and transmission quality of multi antenna systems that operate under various channel conditions. The propagation channel follows the IEEE 802.11n specifications. The influence of the diversity order and the spatial correlation is investigated in terms of error performance and throughput. The efficient use of the space and the power resources leads to significant improvement in the link reliability, if channel state is available at the transmission. The throughput enhancement of a 2×2 MIMO system relatively to the basic SISO (Single Input Single Output) mode is evaluated considering a fix antennas separation and different channel models.

An Innovative QoS Paradigm Based on Cognitive In-network Management of Resources for a Future Unified Network Architecture: I-NAME QoS Model

The goal of this paper is to present an innovative QoS solution of managing resources by knowing the service requests and the network context in a unified network architecture. Considering the nowadays technical solutions and the holistic vision of the future network of information, this solution is proposing a cognitive QoS model of self-managing resources by using the network virtualization concept in conjunction with the in-network management concept. Thus, the main goal of the paper is to solve resource management problem inside a unified network architecture remodeled by the actual trends in the field – virtualization and in-network management – by validating while evaluating the I-NAME QoS proposed model.

Spatial multiplexing and diversity in a MIMO based WLAN system

Spatial processing techniques are considered as means to enhance the performance of WLANs systems. Different multi-antenna methods exploit different properties of the radio channel, so in this paper, we identify, based on the channel state, the physical layer parameters that can be controlled in the attempt to satisfy the user/application requirements, with an efficient use of the available radio resources. Performance criteria considered for the evaluation are the packet error rate and the throughput. Channel state information at the transmitter provides link speed enhancement especially for high transmit diversity system and low values of the signal to noise ratio.

Some aspects regarding radio resources management in multi-antenna systems

In this paper, multi-antennas transmission techniques, based on spatial multiplexing and space diversity, are considered as means to enhance the performance of WLANs systems. Link adaptation is introduce in order to determine the most appropriate PHY configuration in terms of achievable throughput and error performance, for different configuration of transmit and receive antennas, modulation scheme and coding rates. The physical layer parameters selection is done according to the application requirements, in the attempt to efficiently use the available radio resources.