Emanuel Puschita

Wireless LAN medium access techniques QoS perspective

Different people and communities perceive and interpret Quality of Services (QoS) in different ways. We consider that QoS problem has two major perspectives: (1) network perspective and (2) application/user perspective. Networks receive from the applications implicitly or explicitly their QoS parameters and need to respond to these requests by supplying QoS services. The papers analyze QoS parameters from the network perspective looking on medium access control layer (DCF and EDCF medium access techniques). The essential aim of the paper is to illustrate and demonstrate 802.11e effects on traffic priority. We use ns-2.26 simulator in our simulation scenarios.

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.

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.

Assessing VoLTE performances for fundamental E-UTRAN technologies

As the LTE network infrastructure is currently in development, this paper provides an objective assessment of the VoIP performances for an LTE cell deployed in a 3D modeled urban area. Fundamental E-UTRAN technologies have been tested in the LTE cell used at full capacity for the 1.4MHz and 5MHz channel bandwidths. The VoLTE performance improvements are evaluated in terms of QoS and QoE parameters. The simulation results provide useful insights for the operators regarding an efficient LTE network planning.

Spectral efficiency improvement for the under-11GHz Broadband Wireless Access

Our evaluation is performed in the context of a study of adaptive radio techniques, in the attempt to improve link availability and transmission quality of BWA (broadband wireless access) systems, and to achieve an efficient use of radio resources. As part of an evaluation of coexistence issues in the under-11 GHz bands, we have analysed several adaptive techniques currently in use in IEEE 802.16 and IEEE 802.11 (a, b, g) standards. This paper is focused on the spectral efficiency and BER performance of the 802.16 FEC block. One of our goals was to study the effect of the interleaving process on the spectrum efficiency for different environments modelled by different radio channels. Another goal was to measure the system throughput and the delay introduced by the interleaver in the presence of noise, these enabling us to investigate from which BER and/or SNR threshold the interleaver can increase the overall spectrum efficiency. In the end, we identify six evaluation criteria for an adaptive FEC (forward error correction) scheme that can improve the performance, in terms of throughput, in an 802.16 SC system. The detailed observations will enable us to set the premour evaluation is performed in the context of a study of adaptive radio techniques, in the attempt to improve link availability and transmission quality of BWA (broadband wireless access) systems, and to achieve an efficient use of radio resources. As part of an evaluation of coexistence issues in the under-11 GHz bands, we have analysed several adaptive techniques currently in use in IEEE 802.16 and IEEE 802.11 (a, b, g) standards. This paper is focused on the spectral efficiency and BER performance of the 802.16 FEC block. One of our goals was to study the effect of the interleaving process on the spectrum efficiency for different environments modelled by different radio channels. Another goal was to measure the system throughput and the delay introduced by the interleaver in the presence of noise, these enabling us to investigate from which BER and/or SNR threshold the interleaver can increase the overall spectrum efficiency. In the end, we identify six evaluation criteria for an adaptive FEC (Forward Error Correction) scheme that can improve the performance, in terms of throughput, in an 802.16 SC system. The detailed observations will enable us to set the premises for new adaptive strategies at the PHY and MAC layer is set for new aadaptivedaptive strategies at the PHY and MAC layer.

GPStation-6 employment for GNSS TEC monitoring in SIRIUS project

HF communications have proved to be a quick and reliable solution for encrypted data transmissions in scenarios where other infrastructure is damaged or inexistent. However, the behavior of the ionosphere has to be predicted in order to model a suitable radio link and overcome the errors introduced during ionospheric propagation. As a partner in the SIRIUS project, the Technical University of Cluj-Napoca has acquired, installed and employed the NovAtel GPStation-6, a GNSS ionospheric scintillation and TEC monitor receiver to estimate the electronic density and to be used in the validation of the ionospheric model developed within the project. This paper aims at presenting the capabilities of the GNSS receiver, its installation, the calibration process, and TEC measurements.

Performance evaluation of a fuzzy-based QoS support implementation

The task of Quality-of-Service (QoS) routing is to find a path in the network that satisfies certain constraints on metrics such as delay, jitter, bandwidth and packet loss. All routing algorithms are designed for intra-domain QoS support, and when multiple technologies are interconnected, a proper end-to-end QoS support cannot be guaranteed. This paper proposes a method for the most suitable end-to-end path selection in a unified network architecture. The solution is implemented in two phases: firstly, the network is tested in order to obtain a list of all possible routes and secondly, the best path is selected using the fuzzy logic algorithm. This solution has been implemented and validated through network simulations.

HCCA support in IEEE 802.11 networks QoS and QoE performance evaluation

The profile of the service users in telecommunication networks shows a continuous growth in the interest towards real-time applications (streaming and interactive video, web conferences, voice over IP). In order to assure the optimal parameters for this kind of transmissions, the implementation of mechanisms that provide service quality support is mandatory. One way of assuring the QoS support in IEEE 802.11 networks is to enable the HCCA mechanism. This paper provides an objective analysis of the performances of the HCCA mechanism regarding voice and video applications by means of the evaluation of specific QoS/QoE parameters: delay, jitter and MOS.

WiMAX in-network QoS dependencies: Application requests and network capabilities

The purpose of this paper is to evaluate the effect of scheduling algorithms over the guaranteed QoS level of services in a WiMAX network, by identifying and indicating the in-network QoS dependencies. Due to the fact that the IEEE 802.16 standard does not specify the scheduling algorithm for the five classes of services, the network operator must choose one of the traffic scheduling techniques in order to maintain the QoS support level. Therefore, this paper shows that selecting a technique for traffic scheduling is defined at the conjunction of application requirements and network capacity, identified as in-network QoS dependencies.