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Latin America is living the migration towards the digital terrestrial television (DTT) with the ISDB-Tb standard. Some countries have even had the analog blackout. In relation to the Emergency Warning Broadcast System (EWBS), the process of transmission and reception is defined. In recent years, tests have been coordinated for the process of implementing EWBS for DTT. The Common Alert Protocol (CAP) allows emergency alerts to be exchanged between different communication systems. This article presents the implementation of a CAP module in a Spatial Data Infrastructure for risk management and integration of the EWBS for DTT in a single platform for emergency alerts. A web service that contains the codes representing the cantons of Ecuador was obtained, selected through the use of a map viewer and integrated with an application that processes this information and generates the alert to be transmitted via DTT. The main objective is the storage of the information in a database, and a WEB RSS service that contains the information in conformance with CAP format. A series of experiments show successful outcomes.

Being part of the so-called “Pacific Ring of Fire” and “Belt of Low Pressure,” Ecuador is located in one area most likely to suffer seismic, volcanic, and hydrometeorological threats, which make it possible to catalog as a country with a high vulnerability. For this reason, the use of alert systems such as Emergency Warning Broadcasting System EWBS is necessary for the face of one of these threats, which can be implemented in analog and digital broadcast signals such as Digital Terrestrial Television. In an emergency, the receivers compatible with the EWBS are currently the decoders or digital televisions that include this system. They turn on automatically and emit a visual and audible alert signal that gives time to the population to act more quickly to an event. This article presents the design proposal of a receiver that replicates the warning emergency alert EWBS for digital terrestrial television with the ISDB-Tb standard, through an institutional telephone PBX, implementing an IP telephony server that receives the EWBS system and replicates it to landlines, infocast systems, and mobile phones connected to it, thus avoiding a percentage of losses in the economic and human fields.

This article presents an architectural solution to incorporate Ecuadorian sign language into the country’s free and open digital television system. Initially, a transport stream was generated with the Closed Caption service as a result of automatic transcription from audio to text, based on the regulations of the ISDB-T digital television standard, established by the Association of Broadcasting Industries and Negotiations. Later, an algorithm was developed that allows the extraction of the Closed Caption text and generates the insertion of video tracks in Ecuadorian sign language, called LSEC tracks, in the original multimedia content.

This article presents a pilot solution for the automatic insertion of video tracks in Ecuadorian sign language in the multimedia content of Digital Terrestrial Television, in order to reduce the barriers that are inserted for people with hearing disabilities when accessing to information due to their inherent difficulties in dealing with spoken and written languages. Initially, a transport type TS (Transport Stream) with Closed Caption service was generated, based on the standards of the ISDB-Tb digital television standard, established by ARIB (Association of Broadcasting Industries and Businesses). Later an algorithm is specified that allows the extraction of the Closed Caption text and generates the insertion of Ecuadorian sign language video tracks, called LSEC tracks, in the original multimedia content. These video tracks were created by the authors and represent words from the oral language, in Ecuadorian sign language through a 3D-avatar. Finally, a qualitative evaluation was carried out on the accessible content generated by the proposed solution and an analysis of the results obtained is presented.

As telecommunication systems evolve towards new-generation architectures, likewise, new protocols are created in order to improve efficiency. One of these protocols is Transmission Control Protocol (TCP), which controls the transmission bit rate in function of network congestion. Nevertheless, in wireless communications, there appear problems such as noise and interference, for which TCP was not designed. Based on these problems, there exist some methods trying to mitigate congestion, such as explicit loss notifications and the use of end-to-end codification. The aim of this work was to propose a wireless TCP protocol improvement, considering a negative acknowledgment (NACK), which allows to differentiate between losses due to congestion and losses due to wireless channel issues. NACK employs a small protocol packet and produces improvement in the quality of service metrics. The experiments were carried out in in-door and out-door environments, over an online video game scenario, and over a long-distance wireless link between two islands. The average results show a 25-percent delay improvement and a 5-percent jitter improvement when compared to the original TCP Reno protocol, while for throughput a 90-percent improvement was achieved for distances between 100 and 414 m.

This paper presents the performance analysis of a new TCP algorithm designed for wireless networks on a realtime scenario compared to the generic TCP algorithm. Our work considers two network scenarios: indoor and outdoor with point-multipoint topology. The performance evaluation considers the throughput, jitter and delay metrics, to obtain these metrics the intrusive traffic injection technique was used using the D-ITG software, while for the qualitative analysis the Mean Opinion Score technique was used through a survey to establish a subjective measure of the quality perceived by the user based on the different network conditions. The results indicate that the new TCP algorithm presents a significant improvement of reduction by approximately 6% compared to jitter and delay metrics.

Several images are used as a part of the interactive data in the Nipo-Brazilian digital TV system that require good subjective quality while using the lowest possible bandwidth but the well-known traditional compression systems are already applied by default to these images. The concept of a mosaic image (several images forming one) has been formerly used in the steganography application field. The mosaic image is obtained by reordering the image-blocks of a secret image disguised as another image, the so-called target image, and then feeding both to a near reversible color-transformation algorithm. Its use is a possible solution to this need in digital interactive television, for which the main challenge is to achieve this by using less bandwidth for transmission. We propose here a procedure to reduce the amount of data needed to recover the secret image from the mosaic image, as well as a criterion to select the target image and therefore improve the quality of the recovered secret image in interactive data applications. The main objective is to efficiently transmit two images as one using a lower bandwidth. On the one hand, the number of bits needed to recover a given secret image is highly reduced by modeling the image-block standard deviation statistical distribution. On the other hand, the entropy of the image-block means and standard deviations per color component are used to identify the most convenient target image among the images set present in the interactive application of interest. A series of experiments with a set of 20 mostly natural images showed a reduction in the number of bits close to 3-to-1 with respect to techniques of reference. The proposed method allows us to improve the bandwidth use by reducing the number of bits needed to recover the secret image, it preserves the subjective quality of recovered secret images, and it gives the possibility to determine the best target images available in several multimedia and digital terrestrial television applications.

El dinero electrónico es un medio de pagos implementado por el Banco Central del Ecuador, el cual permite a las personas realizar transacciones comerciales desde su celular; este se puede utilizar para efectuar pagos en grandes establecimientos comerciales denominados “macro agentes”, entre los que se encuentran las cadenas de supermercados, pero también se puede utilizar para realizar consumos en todo tipo de negocios particulares como restaurantes, tiendas, etc., mediante transferencias de “persona a persona” denominadas P2P. Sin embargo, el sistema de dinero electrónico, SDE, tal como está concebido induce ciertas desventajas competitivas entre los negocios particulares y los macro agentes; la principal radica en que los primeros no cuentan con un sistema que les permita llevar registro de los cobros efectuados con dinero electrónico. El presente artículo detalla la creación de una plataforma tecnológica que permite actualmente a todo tipo de negocios y personas llevar registro de sus transacciones P2P, mediante una solución automatizada con capacidad de generar balances de los pagos recibidos, los cuales se pueden visualizar fácilmente a través de Internet. Para esto se llevó a cabo un análisis profundo del funcionamiento del SDE, con el fin de establecer una solución eficiente al problema, procurando siempre optimizar recursos.

This work shows the implementation of a hybrid STB (Set Top Box) that receives real-time digital signals for ISDB-Tb and IPTV. The implementation integrates middleware GINGA for interactive DTT applications based on low cost platforms. The features of the hardware platform for this implementation are analyzed so that they can integrate USB reception modules for digital TV, support interactive middleware versions and also be compatible with TV playback software by means of internet protocols. After the analysis and evaluation, we found that the most suitable board to achieve this implementation was Raspberry Pi 3. The development of the Android mobile graphic interface is also shown, which emulates a remote control by Bluetooth technology. Finally, the results of the implemented hybrid STB’s evaluation are presented; evaluation performed by reception tests of DTT channels with interactivity and free IPTV channels. Also, quantitative readings were made to test the performance and correct operation, as well as qualitative MOS polls to get the quality of user experience when handling the decoder.

The results of transmission and reception broadcast tests of the Emergency Warning Broadcast System (EWBS) for Digital Terrestrial Television in the city of Quito-Ecuador with the ISBD-T standard are presented in this paper, in coordination with government agencies and private companies. The system consists of an EWBS server developed and implemented by the authors, which modifies the text overlay message and the PSI tables for some-emergency-codes transmission, as established in the EWBS international harmonization document, while re-configuring the multiplexing and transmission stage of the television station. The tests were carried out in two stages, on the one hand working directly with the multiplexers and modulators of digital terrestrial television from Pichincha hill, and on the other hand from television station with a microwave transport network to Pichincha hill. It was possible make the activation of the EWBS receivers in the coverage region, select codes, and reception of the overlay message, with an nearly imperceptible delay in the complete system, within real time requirements.

In this paper we propose the implementation of the digital terrestrial television receiver under the ISDB-Tb (Integrated Services Digital Broadcasting-Terrestial Build-in) standard for the mobile service in the device based in Radio Defined by Software USRP (Universal Software Radio Peripheral). The implemented reception system allows recovering the digital signal in narrow band to observe in real time the different channels and at the same time determine its quality through objective measures. A mathematical algorithm was implemented for the perfect synchronization in time and frequency of the signal of OFDM (Orthogonal Frequency Division Multiplexing), reducing the harmful effects of channel and increasing receiver efficiency.

This project presents the analysis and performance evaluation for digital terrestrial television transmitter stations for mobile broadcasting using ISDB-T standard over AWGN and fading channel. A main broadcast transmitter with a secondary transmitter has been evaluated. The second station works with a lower power regarding the main broadcast transmitter, for this project with a 100:1 ratio. Under this scenario, two working options has been defined: (i) both stations transmit the same information, where the secondary station was considered as a repeater station, and (ii) both stations transmit different information, building an environment of co-channel interference. The performance by the bit error rate as a function of the receiver location was presented. The simulation and theoretical results show the improvement or deterioration of the signal, respectively to the working options stablished for the ISDB-T standard's A layer in order to validate repeater stations for digital terrestrial television mobile broadcasting.

This article presents a mobility application of navegation directed to people with visual deficiency and disability. Visually disabled people cope with daily challenges in mobility and in their automony. VOICE-TOUCH GPS is an application that has two forms in order to interact with them. The first one lets the person use a smartphone with touch screen to have an auditory feedback. The second one interacts by means of a synthesizer which generates a text by voice and vice-versa. The application presents a graphic interface easy to use along with the help of a GPS. It will help the user know the latest location, the nearest bus stop, buses routes, make phone calls and send messages predetermined to the location. Furthermore, this article presents the functions of the application, requirements of functioning, social impact and the results obtained in people with total and partial visual deficiency in Ecuador.

The present article describes the creation of a MPEG-2 Transport Stream (TS)/Broadcast Transport Stream (BTS) Analyzer for Digital Television. This analyzer recognizes TS and BTS files in a decimal or hexadecimal format and it shows the components of the PSI (Program Service Information)/SI (Service Information) Tables, such as: Program Association Table (PAT), Program Map Table (PMT), Network Information Table (NIT), and Service Descriptor Table (SDT); in the case of the BTS files it also shows the content of the Transmission and Multiplexing Configuration (TMCC) table. The software has a package search system where you can look for a package through his PID (Program Identification) number or his package number. It also allows surfing between all the packages or the packages with the same PID number.

This paper shows the design, implementation and evaluation of an algorithm that allows the extraction of Transport Stream's (TS) data section for Digital Terrestrial Television (DTT), with the organization in a hierarchical file system and directories based on MPEG-2 standard ISO-13818-6: Extension for Digital Storage Media Command and Control (DSM-CC), in order to fully recover the media from interactive applications contained by the MPEG-2 TS stream. To check the validity of the algorithm, it was implemented in a software to evaluate the application extraction of different TS, verifying its correct operation, as it successfully recovered all directories and files from interactive applications.

Two important aspects about UMTS/HSPA (Universal Mobile Telecommunications Service/High Speed Packet Access) and LTE (Long Term Evolution) systems are analyzed. First, an analysis of the frequency bands allocated in Ecuador for the cellular systems is made. Then, expressions for the mean bit error rate in a AWGN channel and the presence of co-channel interference is carried out both for WCDMA (Wideband - Code Division Multiple Access) and OFDMA (Orthogonal Frequency Division Multiple Access). Because the necessity of support the increase of traffic due to the emergence of new mobile broadband services, the deployment of LTE networks is necessary. Hence, in Ecuador, new spectrum bands were allocated to the cellular systems. Initially, the bands of 850 MHz and 1900 MHz were available for GSM (Global System for Mobile Communications), EDGE (Enhanced Date Rates For GSM Evolution) and UMTS/HSPA techniques. Nowadays, the country also has the bands of 700 MHz, 1700–2100 MHz (AWS - Advanced Wireless Services) and 2.5 GHz to deploy cellular systems. Also, it is shown that WCDMA provides higher immunity against the co-cell interference, but due to the computational simplicity of the OFDMA technique, it is employed in the new cellular systems.

In this paper we evaluate the performance of the new algorithm of the TCP protocol for a long distance wireless link in the Galapagos Islands. In order to achieve this goal, it has been started from a study of different standards and tools for this project, besides of the amendments to the TCP protocol for wireless environments. Finally, the network was implemented and preceded to inject traffic to evaluate the performance of the TCP protocol. The results showed that the modified TCP protocol with a window of 15 is more appropriate, however, it was noted the need to optimize the sensing mechanism of the error type to improve wireless TCP performance by using cross layer design. With the intention of optimizing the TCP performance, we have mathematically modeled the RTT value that should be used to calculate the appropriate RTO.

In this article, the normalized throughput and the normalized average delay for the transport layer at the reverse link of multicellular CDMA systems are obtained. For the transport layer the Transport Control Protocol (TCP) with consecutive retransmissions control is employed. On the radio link layer three TCP error control strategies are evaluated and compared. The first strategy is based on the radio-link-protocol (RLP), which breaks down the TCP packets into smaller blocks and uses an error detecting procedure to protect those RLP blocks. The second strategy uses forward-error-control (FEC) procedure at the radio link layer. In this case, two kinds of FEC are compared: convolutional and turbo coding. The third one is a hybrid between the first and second strategies with coding at the RLP layer. A frequency-selective Rayleigh fading channel with shadowing and power control loop error is considered.

This article describes the performance evaluation of a new wireless TCP algorithm in real environments, in order to identify the advantages and disadvantages of its operation. We evaluate the proposed wireless TCP algorithm with respect to generic TCP, considering an intrusive technique by using traffic injection. These tests were performed over point-to-point WiFi and WiMAX links in out-door and in-door environments. The proposed amendment for wireless TCP was incorporated in a virtual machine under Linux operating system, and using D-ITG tool for the traffic injections. We assess the performance of the proposed algorithm in terms of the main parameters of Quality of Service (QoS) as throughput, delay, and jitter. Our primary results demonstrate that our new proposal of the TCP algorithm presents better results in comparison with the generic TCP referred to all terms of QoS in wireless environments.

The evolution of wireless networks and the low cost of WiFi technology, have enabled a promising scenario for deployment of these kind of networks in rural areas, as an effective alternative to interconnect distanced sites above tens kilometers. This work presents the results of the performance evaluation of a network with WiLD technology, based on simulation and a deployment in the Andean region of Ecuador, between a station located at Special Forces in Latacunga with an station located at Cerro Pilisurco, distanced approximately 32 km. The main difference between the results obtained in simulation and in the experimental deployment refers, while the simulator allowed to change values corresponding to the physical and link layer, we were unable to control values concerning to delays due to processing and the propagation model, which did not consider regional climatic factors. The link presents a normalized throughput of 0.3 and a mean delay of 5s.

This article describes the analysis of return channel for digital terrestrial television (DTT), through the development of interactive application called Shopping Car buying and selling. Using the middleware Ginga-NCL, Lua and MySQL, to get evidence of the return path for the interactive application and determines the capacity of server performance.