Jose M. Jimenez

Underwater Acoustic Modems

Due to the growing interest using underwater acoustic networks, there are more and more research papers about underwater communications. These papers are mainly focused on deployments and studies about the constraints of the underwater medium. The underwater acoustic channel is highly variable and the signal transmission can change according to environmental factors, such as the temperature, pressure, or salinity of the water. For this reason, it is important to know how these devices are developed and the maximum distance and data transfer rates they can achieve. To this end, this paper presents an exhaustive study of existing underwater acoustic modems where their main features are highlighted. We also review the main features of their hardware. All presented proposals in the research literature are compared with commercial underwater acoustic modems. Finally, we analyze different programs and improvements of existing network simulators that are often used to simulate and estimate the behavior of underwater networks.

Study of Multimedia Delivery over Software Defined Networks

Software Defined Networks (SDN) have become a new way to make dynamic topologies. They have great potential in both the creation and development of new network protocols and the inclusion of distributed artificial intelligence in the network. There are few emulators, like Mininet, that allow emulating a SDN in a single personal computer, but there is lack of works showing its performance and how it performs compared with real cases. This paper shows a performance comparison between Mininet and a real network when multimedia streams are being delivered. We are going to compare them in terms of consumed bandwidth (throughput), delay and jitter. Our study shows that there are some important differences when these parameters are compared. We hope that this research will be the basis to show the difference with real deployments when Mininet is used.

Multimedia sensors embedded in smartphones for ambient assisted living and e-health

Nowadays, it is widely extended the use of smartphones to make human life more comfortable. Moreover, there is a special interest on Ambient Assisted Living (AAL) and e-Health applications. The sensor technology is growing and amount of embedded sensors in the smartphones can be very useful for AAL and e-Health. While some sensors like the accelerometer, gyroscope or light sensor are very used in applications such as motion detection or light meter, there are other ones, like the microphone and camera which can be used as multimedia sensors. This paper reviews the published papers focused on showing proposals, designs and deployments of that make use of multimedia sensors for AAL and e-health. We have classified them as a function of their main use. They are the sound gathered by the microphone and image recorded by the camera. We also include a comparative table and analyze the gathered information.

A QoS-Based Wireless Multimedia Sensor Cluster Protocol

Wireless Sensor Networks (WSNs) provide a wireless network infrastructure for sensed data transport in environments where wired or satellite technologies cannot be used. Because the embedded hardware of the sensor nodes has been improved very much in the last years and the number of real deployments is increasing considerably, they have become a reliable option for the transmission of any type of sensed data, from few sensed measures to multimedia data. This paper proposes a new protocol that uses an ad hoc cluster based architecture which is able to adapt the logical sensor network topology to the delivered multimedia stream features, guaranteeing the quality of the communications. The proposed protocol uses the quality of service (QoS) parameters, such as bandwidth, delay, jitter, and packet loss, of each type of multimedia stream as a basis for the sensor clusters creation and organization inside the WSN, providing end-to-end QoS for each multimedia stream. We present real experiments that show the performance of the protocol for several video and audio cases when it is running.

An architecture to connect disjoint multimedia networks based on node's capacity

TCP/IP protocol suite allows building multimedia networks of nodes according to nodes’ content sharing. Some of them have different types of protocols (some examples given in unstructured P2P file-sharing networks are Gnutella 2, FastTrack, OpenNap, eDonkey and so on). This paper proposes a new protocol to connect disjoint multimedia networks using the same resource or content sharing to allow multimedia content distribution. We show how nodes connect with nodes from other multimedia networks based on nodes’ capacity. The system is scalable and fault-tolerant. The designed protocol, its mathematical model, the messages developed and their bandwidth cost are described. The architecture has been developed to be applied in multiple types of multimedia networks (P2P file-sharing, CDNs and so on). We have developed a general-purpose application tool with all designed features. Results show the number of octets, the number of messages and the number of broadcasts sent through the network when the protocol is running.

A new multimedia-oriented architecture and protocol for wireless ad hoc networks

The number of smart phones, tablets, PDAs and other type of mobile devices used regularly by the population is growing fast. They are able to offer high processing capacities while having several wireless interfaces. Wireless ad hoc networks are currently widely used to share resources between users. In this paper, we propose a new multimedia-oriented application layer protocol. It takes into account the multimedia services offered by the nodes in the wireless ad hoc network to select the best multimedia service provider node and to provide the best QoE and quality of service QoS to the nodes participating in the ad hoc network. We will explain the designed protocol and decision algorithms to provide the best multimedia service to the end users. Then, we will show a study case and we will validate our proposed system through the measurements taken from a real test bench. There is no protocol designed such as the one presented in this paper.

802.11g WLANs Design for Rural Environments Video-surveillance

There is a lot of literature where researches show the best way to develop WLANs inside buildings. Their approaches try to provide large coverage and high performance taking into account wall looses and other issues. WLAN outdoor deployments are usually used to provide Internet access for citizens. In this article we show all parameters taken into account and the measurements taken to develop a new type of WLANs: WLAN for rural environments video-surveillance. These types of wireless networks are usually covered by other wireless frequencies, not by 802.11g. First we will start from the election of the MPEG-4 codec that will be used for transmission. It will be chosen as a function of the devices used in the deployment. Second, we will show the issues of a rural environment design and the wireless coverage area mathematical design. We will take into account signal looses given in rural environments. Finally we will show the number of octets per second, the number of messages per second and the network utilization in % measured from a public natural park deployment

Underwater Communications for Video Surveillance Systems at 2.4 GHz

Video surveillance is needed to control many activities performed in underwater environments. The use of wired media can be a problem since the material specially designed for underwater environments is very expensive. In order to transmit the images and videos wirelessly under water, three main technologies can be used: acoustic waves, which do not provide high bandwidth, optical signals, although the effect of light dispersion in water severely penalizes the transmitted signals and therefore, despite offering high transfer rates, the maximum distance is very small, and electromagnetic (EM) waves, which can provide enough bandwidth for video delivery. In the cases where the distance between transmitter and receiver is short, the use of EM waves would be an interesting option since they provide high enough data transfer rates to transmit videos with high resolution. This paper presents a practical study of the behavior of EM waves at 2.4 GHz in freshwater underwater environments. First, we discuss the minimum requirements of a network to allow video delivery. From these results, we measure the maximum distance between nodes and the round trip time (RTT) value depending on several parameters such as data transfer rate, signal modulations, working frequency, and water temperature. The results are statistically analyzed to determine their relation. Finally, the EM waves’ behavior is modeled by a set of equations. The results show that there are some combinations of working frequency, modulation, transfer rate and temperature that offer better results than others. Our work shows that short communication distances with high data transfer rates is feasible.

Providing security and fault tolerance in P2P connections between clouds for mHealth services

The mobile health (mHealth) and electronic health (eHealth) systems are useful to maintain a correct administration of health information and services. However, it is mandatory to ensure a secure data transmission and in case of a node failure, the system should not fall down. This fact is important because several vital systems could depend on this infrastructure. On the other hand, a cloud does not have infinite computational and storage resources in its infrastructure or would not provide all type of services. For this reason, it is important to establish an interrelation between clouds using communication protocols in order to provide scalability, efficiency, higher service availability and flexibility which allow the use of services, computing and storage resources of other clouds. In this paper, we propose the architecture and its secure protocol that allows exchanging information, data, services, computing and storage resources between all interconnected mHealth clouds. The system is based on a hierarchic architecture of two layers composed by nodes with different roles. The routing algorithm used to establish the connectivity between the nodes is the shortest path first (SPF), but it can be easily changed by any other one. Our architecture is highly scalable and allows adding new nodes and mHealth clouds easily, while it tries to maintain the load of the cloud balanced. Our protocol design includes node discovery, authentication and fault tolerance. We show the protocol operation and the secure system design. Finally we provide the performance results in a controlled test bench.

Oceanographic Multisensor Buoy Based on Low Cost Sensors for Posidonia Meadows Monitoring in Mediterranean Sea

There are some underwater areas with high ecological interest that should be monitored. Posidonia and seagrasses exert considerable work in protecting the coastline from erosion. In these areas, many animals and organisms live and find the grassland food and the protection against predators. It is considered a bioindicator of the quality of coastal marine waters. It is important to monitor them and maintain these ecological communities as clean as possible. In this paper, we present an oceanographic buoy for Posidonia meadows monitoring. It is based on a set of low cost sensors which are able to collect data from water such as salinity, temperature, and turbidity and from the weather as temperature, relative humidity, and rainfall, among others. The system is mounted in a buoy which keeps it isolated to possible oxidation problems. Data gathered are processed using a microcontroller. Finally the buoy is connected with a base station placed on the mainland through a wireless connection using a FlyPort module. The network performance is checked in order to ensure that no delays will be generated on the data transmission. This proposal could be used to monitor other areas with special ecological interest and for monitoring and supervising aquaculture activities.