Maria-Dolores Cano

State of the Art in LP-WAN Solutions for Industrial IoT Services

The emergence of low-cost connected devices is enabling a new wave of sensorization services. These services can be highly leveraged in industrial applications. However, the technologies employed so far for managing this kind of system do not fully cover the strict requirements of industrial networks, especially those regarding energy efficiency. In this article a novel paradigm, called Low-Power Wide Area Networking (LP-WAN), is explored. By means of a cellular-type architecture, LP-WAN–based solutions aim at fulfilling the reliability and efficiency challenges posed by long-term industrial networks. Thus, the most prominent LP-WAN solutions are reviewed, identifying and discussing the pros and cons of each of them. The focus is also on examining the current deployment state of these platforms in Spain. Although LP-WAN systems are at early stages of development, they represent a promising alternative for boosting future industrial IIoT (Industrial Internet of Things) networks and services.

Subjective QoE analysis of VoIP applications in a wireless campus environment

The quality perceived by the user, a concept known as Quality of user Experience (QoE), is gaining momentum. Together with the efforts of providing appropriate architectures able to deliver the expected level of Quality of Service (QoS), users’ perception of the level of quality could play a key role in making a VoIP multimedia application to succeed or to fail. QoE can be measured from different approaches; subjective ones are based on polls while objective ones are mainly based on QoS network performance parameters. Although a subjective evaluation could be costly and time consuming, it gives the most accurate results. Moreover, wireless environments incorporate new challenges in terms of QoS and QoE because of inherent wireless communication characteristics. In this way, our contribution is twofold. First, we carry out a subjective QoE assessment for VoIP applications in a real wireless environment. Skype, Gizmo5, ooVoo, and Damaka are the selected VoIP applications under study. Next, we contrast QoE results with QoS evaluation from the captured video calls made during the poll. Results show that there is no precise match on both assessments, because of QoE parameters that cannot be inferred from QoS analysis, because of the different effect of some QoS parameters which prevail, or even because of the popularity of the VoIP application.

Internet measurements and data study over the regional

We present the most significant results studying the Internet network traffic measurements obtained in Ciez@net. Ciez@net is a citizen subnet located in the village of Cieza that belongs to the regional network of the autonomous community of Murcia in Spain. This subnet is one of the firsts pilot experiences of a digital city in Europe and the first in the region of Murcia. The goal is the seamless introduction of the information society in a medium-size population. Access to advanced electronic information services is stimulated or subsidized for effective penetration. These measurements will allow a qualitative and quantitative knowledge of the network traffic in order to achieve a most effective network resource provisioning and Internet traffic forecasting in a real scenario. A suitable dimensioning of the network as well as an adequate provisioning of quality of service to users may depend partially on these results. Measurements were taken from a frame relay link connecting Ciez@nets users to Internet through the main node located in Murcia city. We used a promiscuous network analyzer that avoids interfering with the network traffic. We report the results of the traffic load, network performance, percentage composition of traffic by protocol and type of application, and IP packet size distribution in both, up and down communications streams.

Performance Evaluation of BATMAN Routing Protocol for VoIP Services: A QoE Perspective

MANETs are experiencing unstoppable growth due to their decentralized topology and their easy and low-cost deployment. The dynamic nature of MANETs entails the use of appropriate routing protocols to obtain good performance in the services supported by the network; even more if these services present tough temporal requirements, such as multimedia or VoIP services. One routing protocol to which notable research effort has been devoted is the BATMAN protocol, which proposes an interesting paradigm avoiding the explicit interchange of routing information among nodes. In this paper, we focus on evaluating the performance of BATMAN supporting VoIP traffic on low power-consumption nodes, from a Quality of Experience (QoE) point of view. Specifically, we evaluate the impact on BATMAN performance of 1) the PHY layer, by employing a fading characterization of the transmission channel; 2) the number and density of ad-hoc nodes; and 3) node mobility. All the results obtained for BATMAN are compared with those attained by using the widely used OLSR routing protocol. From the results, we conclude that neither BATMAN nor OLSR in their respective current implementations are suitable enough for VoIP traffic support in MANETs composed of energy-saving nodes.

An approach to a cross layer-based QoE improvement for MANET routing protocols

Currently, multimedia communications are monopolizing Internet traffic. These services present highly demanding real-time requirements that need great bandwidths in order to provide acceptable quality levels. Meanwhile, the variety of network architectures employed by final users to access these contents is wider and wider. One of the most attractive access networks due to its ease-of-deployment and decentralized architecture is the Mobile Ad-hoc NETworks (MANETs). The inherent dynamic nature of these networks entails the use of appropriate routing protocols in order to obtain good performance in the services supported by the system. In this work, we focus on evaluating the performance of the novel routing protocol Better Approach To Mobile Ad-hoc Networking (BATMAN) and the widely extended IETF experimental drafts Optimized Link State Routing (OLSR) and Ad hoc On-Demand Distance Vector (AODV) protocols supporting video traffic. The results obtained from a chain-topology network have been improved in terms of Quality of Experience (QoE) by means of different modifications at different OSI layers. We have found out that each protocol presents low performance in different scenarios that can be enhanced by means of the proposed techniques. As we show in this work, taking a proper action in the right OSI layer permits an improvement on the multimedia traffic support in MANETs.

A secure energy-efficient m-banking application for mobile devices

Mobile banking is one of the emerging services in telecommunications due to the explosive increase in the number of mobile customers around the world. Solutions for mobile banking are varied, ranging from the use of Wireless Transport Layer Security, Security Socket Layer, or application-layer based options. Whereas security at the transport layer is a good choice for e-banking, using it in a mobile device presents several disadvantages such as high energy consumption. In this work, we present a secure energy-efficient m-banking solution for mobile devices. We propose an application-layer protocol whose message formats and message exchanges are designed to reduce time processing, bandwidth use, and energy consumption. Through experimentation, we demonstrate that our secure solution reduces power and energy consumption in more than 30% compared to a secure web-access from the mobile device.

Counters-based modified traffic conditioner

Traffic conditioners play a key role in implementing the Assured Service in the framework of the DiffServ approach. In this paper, we propose a traffic conditioner for the Internet Assured Service called Counters-Based Modified (CBM) that strictly guarantees target rates and performs a fair share of the excess bandwidth among TCP sources. The fairness in the outbound bandwidth distribution is met by probabilistically dropping OUT packets in the traffic conditioner. To determine the dropping probability of an OUT packet, some sort of signaling is needed. Although, it results more feasible than other proposed intelligent traffic conditioners. The CBM traffic conditioner is evaluated under different conditions by simulation using TCP Reno sources.

An Experimental QoE Performance Study for the Efficient Transmission of High Demanding Traffic over an Ad Hoc Network Using BATMAN

Multimedia communications are attracting great attention from the research, industry, and end-user communities. The latter are increasingly claiming for higher levels of quality and the possibility of consuming multimedia content from a plethora of devices at their disposal. Clearly, the most appealing gadgets are those that communicate wirelessly to access these services. However, current wireless technologies raise severe concerns to support extremely demanding services such as real-time multimedia transmissions. This paper evaluates from QoE and QoS perspectives the capability of the ad hoc routing protocol called BATMAN to support Voice over IP and video traffic. To this end, two test-benches were proposed, namely, a real (emulated) testbed and a simulation framework. Additionally, a series of modifications was proposed on both protocols’ parameters settings and video-stream characteristics that contributes to further improving the multimedia quality perceived by the users. The performance of the well-extended protocol OLSR is also evaluated in detail to compare it with BATMAN. From the results, a notably high correlation between real experimentation and computer simulation outcomes was observed. It was also found out that, with the proper configuration, BATMAN is able to transmit several QCIF video-streams and VoIP calls with high quality. In addition, BATMAN outperforms OLSR supporting multimedia traffic in both experimental and simulated environments.

Performance Evaluation of Video Streaming Using MPEG DASH, RTSP, and RTMP in Mobile Networks

Nearly three-fourths of the worlds mobile data traffic will be video in the next 5 years. Video is one of the most demanding services in terms of network efficiency, reliability, and quality. In this work, we present a comparative performance evaluation of three different video streaming protocols, namely MPEG-DASH, RTSP, and RTMP for both on-demand and live video streaming over 4G and Wi-Fi (under different network conditions) in terms of Quality of user Experience (QoE). QoE measurements have been done (i) applying the recently standardized ITU-T Rec P-1201.1, which specifies the model algorithm for non-intrusive monitoring of video quality of IP-based video services based on packet header information for the lower resolution application area, and (ii) an extended non-standardized parametric model for comparative purposes. Results suggest that RTSP is more efficient than MPEG DASH for starting the video playback, but at the expense of decreasing QoE due to packet losses. We have also detected that PLR has a bigger influence over re-buffering events than end-to-end delay both in 4G/LTE and Wi-Fi, and that a slightly best quality is achieved by using QPSK at 20 MHz in 4G/LTE. QoE is noticeably higher with MPEG DASH than that attained by using RTSP, but slightly worse than that obtained with RTMP. Finally, our findings suggest that the use of parametric models for video QoE evaluation should be carefully review in terms of the weight that packet losses should have when streaming protocols based on reliable transport protocols (e.g., TCP) are used.

Performance evaluation of QoE in VoIP traffic under fading channels

Voice over IP (VoIP) and wireless networks are technologies that are receiving an increasing interest by both, the research community and the final users. For instance, the effect of layer two handoffs, delay constraints, channels with constant bit error rates, packet size, UDP traffic, TCP traffic, overheads from different layers, etc., have been exhaustively evaluated for VoIP over wireless networks. Surprisingly, the effect of the physical layer has been barely addressed in the related literature. This paper evaluates, via computer simulation, the effect of fading channels on VoIP traffic for IEEE 802.11 systems and its influence on the Quality of user Experience (QoE). We use the Nakagami-m propagation model in order to represent different physical radio propagation environments. A complete study about the effect of fading over system capacity, coverage range, and QoE is provided. To this end, we simulate several scenarios, with different codecs, different packetization time intervals, and different bandwidths. From the results achieved, we observe that fading channels have i) a severe impact on the network capacity, represented by a reduction in the maximum number of valid VoIP supported calls, ii) a reduction of the network coverage accepting VoIP calls, and iii) a degradation of the QoE evidenced by a reduction of the assessed Mean Opinion Score.