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Tuesday, 30 June 2015

piconet (red informática)

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Un piconet es una red informática que une un grupo de usuarios de dispositivos inalámbricos que utilizan protocolos de tecnología Bluetooth. Una piconet consta de dos o más dispositivos que ocupan el mismo canal físico (sincronizado con un reloj común y secuencia de salto). Se permite que un dispositivo maestro para interconectar con hasta siete dispositivos esclavos activos. Hasta 255 más dispositivos esclavos pueden estar inactivo, o estacionado, que el dispositivo maestro puede poner en estado activo en cualquier momento.
Algunos ejemplos de piconets incluyen un teléfono celular conectado a un ordenador, un ordenador portátil y una cámara digital compatible con Bluetooth, o varias PDAs que están conectados entre sí
Un grupo de dispositivos se conectan a través de la tecnología Bluetooth de manera ad hoc. Un piconet comienza con dos dispositivos conectados, y puede crecer hasta ocho dispositivos conectados. Comunicación Bluetooth siempre designa uno de los dispositivos Bluetooth como una unidad de control principal o unidad principal. Otros dispositivos que siguen a la unidad principal son unidades esclavas. Esto permite que el sistema Bluetooth para ser no basado en contienda (colisiones). Esto significa que después de un dispositivo Bluetooth se ha añadido a la piconet, cada dispositivo se le asigna un período de tiempo específico para transmitir y no chocan o se superponen con otras unidades que operan en la misma piconet.
Gama Piconet varía de acuerdo a la clase de dispositivo Bluetooth. Tasas de transferencia de datos varían entre 200 y 2100 kilobits por segundo.
Debido a que el sistema Bluetooth lúpulo más de 79 canales, la probabilidad de interferir con otro sistema Bluetooth es menor que 1,5%. Esto permite que varias piconets Bluetooth para operar en la misma zona al mismo tiempo con una mínima interferencia.
El piconet original era un tipo de red utilizado en las computadoras producidas por Nimbus RM plc.

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Piconet (computer network)


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piconet is a computer network which links a wireless user group of devices using Bluetooth technology protocols. A piconet consists of two or more devices occupying the same physical channel (synchronized to a common clock and hopping sequence). It allows one master device to interconnect with up to seven active slave devices. Up to 255 further slave devices can be inactive, or parked, which the master device can bring into active status at any time.
Some examples of piconets include a cell phone connected to a computer, a laptop and a Bluetooth-enabled digital camera, or several PDAs that are connected to each other
A group of devices are connected via Bluetooth technology in an ad hoc fashion. A piconet starts with two connected devices, and may grow to eight connected devices. Bluetooth communication always designates one of the Bluetooth devices as a main controlling unit or master unit. Other devices that follow the master unit are slave units. This allows the Bluetooth system to be non-contention based (no collisions). This means that after a Bluetooth device has been added to the piconet, each device is assigned a specific time period to transmit and they do not collide or overlap with other units operating within the same piconet.
Piconet range varies according to the class of the Bluetooth device. Data transfer rates vary between about 200 and 2100 kilobits per second.
Because the Bluetooth system hops over 79 channels, the probability of interfering with another Bluetooth system is less than 1.5%. This allows several Bluetooth Piconets to operate in the same area at the same time with minimal interference.
The original piconet was a networking type used on Nimbus computers produced by RM plc.
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Monday, 29 June 2015

wireless local area network (WLAN)


wireless local area network (WLAN) is awireless computer network that links two or more devices using a wireless distribution method (often spread-spectrum or OFDM radio) within alimited area such as a home, school, computer laboratory, or office building. This gives users the ability to move around within a local coverage area and still be connected to the network, and can provide a connection to the wider Internet. Most modern WLANs are based on IEEE 802.11standards, marketed under the Wi-Fi brand name.
Wireless LANs have become popular in the home due to ease of installation and use, and in commercial complexes offering wireless access to their customers; often for free. New York City, for instance, has begun a pilot program to provide city workers in all five boroughs of the city with wirelessInternet access.
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mobile computing devices

Some of the most common forms of mobile computing devices are as follows.
  • portable computers, compacted lightweight units including a full character set keyboard and primarily intended as hosts for software that may be parametrized, as laptops, notebooks, notepads, etc.
  • mobile phones including a restricted key set primarily intended but not restricted to for vocal communications, as cell phones, smart phones, phonepads, etc.
  • Smart cards that can run multiple applications but typically payment, travel and secure area access
  • wearable computers, mostly limited to functional keys and primarily intended as incorporation of software agents, as watches, wristbands, necklaces, keyless implants, etc.
The existence of these classes is expected to be long lasting, and complementary in personal usage, none replacing one the other in all features of convenience.
Other types of mobile computers have been introduced since the 1990s including the:

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Saturday, 27 June 2015


Smartphone (or smart phone) is a mobile phone with an advanced mobile operating system.They typically combine the features of a cell phone with those of other popular mobile devices, such as personal digital assistant (PDA), media player and GPS navigation unit. Most smartphones have a touchscreen user interface, can run third-partyapps and are camera phones. Most Smartphones produced from 2012 onwards also have high-speed mobile broadband 4G LTE internet, motion sensors, and mobile paymentmechanisms.
In 2014, sales of smartphones worldwide topped 1.2 billion, which was up 28% from 2013.
Devices that combined telephony and computing were first conceptualized byTheodore Paraskevakos in 1971 and patented in 1974, and were offered for sale beginning in 1993. He was the first to introduce the concepts of intelligence, data processing and visual display screens into telephones which gave rise to the "smartphone." In 1971, Paraskevakos, working with Boeing in Huntsville, Alabama, demonstrated a transmitter and receiver that provided additional ways to communicate with remote equipment, however it did not yet have general purposePDA applications in a wireless device typical of smartphones. They were installed at Peoples' Telephone Company in Leesburg, Alabama and were demonstrated to several telephone companies. The original and historic working models are still in the possession of Paraskevakos

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Friday, 26 June 2015

Personal digital assistant (PDA)

personal digital assistant (PDA), also known as a handheld PC, orpersonal data assistant, is a mobile device that functions as a personal information manager. The term evolved from Personal Desktop Assistant, a software term for an application that prompts or prods the user of a computer with suggestions or provides quick reference to contacts and other lists. PDAs were largely discontinued in the early 2010s after the widespread adoption of highly capable, in particular iOS and Android-based, smartphones.
Nearly all PDAs have the ability to connect to the Internet. A PDA has anelectronic visual display, enabling it to include a web browser, all models also have audio capabilities enabling use as a portable media player, and also enabling most of them to be used as mobile phones. Most PDAs can access the Internet, intranets or extranets via Wi-Fi or Wireless Wide Area Networks. Most PDAs employ touchscreen technology.
The first PDA was released in 1984 by Psion, the Organizer. Followed by Psion's Series 3, in 1991, which began to resemble the more familiar PDA style. It also had a full keyboard. The term PDA was first used on January 7, 1992 by Apple Computer CEO John Sculley at the Consumer Electronics Show in Las VegasNevada, referring to the Apple Newton. In 1994, IBM introduced the first PDA with full mobile phone functionality, the IBM Simon, which can also be considered the first smartphone. Then in 1996, Nokia introduced a PDA with full mobile phone functionality, the 9000 Communicator, which became the world's best-selling PDA. The Communicator spawned a new category of PDAs: the "PDA phone", now called "smartphone". Another early entrant in this market was Palm, with a line of PDA productswhich began in March 1996.

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A thread of execution in computer science

In computer science, a thread of execution is the smallest sequence of programmed instructions that can be managed independently by a scheduler, which is typically a part of the operating system. The implementation of threads and processes differs between operating systems, but in most cases a thread is a component of a process. Multiple threads can exist within the same process and share resources such as memory, while different processes do not share these resources. In particular, the threads of a process share its instructions (executable code) and its context (the values of its variables at any given moment).
On a single processor, multithreading is generally implemented by time slicing(as in multitasking), and the central processing unit (CPU) switches between different software threads. This context switching generally happens frequently enough that the user perceives the threads or tasks as running at the same time. On a multiprocessor or multi-core system, threads can be executed in a true concurrent manner, with every processor or core executing a separate thread simultaneously; on a processor or core with hardware threads, separate software threads can also be executed concurrently by separate hardware threads.
Threads made an early appearance in OS/360 Multiprogramming with a Variable Number of Tasks (MVT) in 1967, in which they were called "tasks". Process schedulers of many modern operating systems directly support both time-sliced and multiprocessor threading, and the operating system kernel allows programmers to manipulate threads by exposing required functionality through the system call interface. Some threading implementations are called kernel threads, whereas lightweight processes (LWP) are a specific type of kernel thread that share the same state and information. Furthermore, programs can have user-space threads when threading with timers, signals, or other methods to interrupt their own execution, performing a sort of ad hoc time-slicing

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Mobile application development

Mobile application development is a term used to denote the act or process by which application software is developed for handheld devices, such as personal digital assistantsenterprise digital assistants or mobile phones. These applications can be pre-installed on phones during manufacturing platforms, or delivered as web applications using server-side or client-side processing (e.g. JavaScript) to provide an "application-like" experience within a Web browser. Application software developers also have to consider a lengthy array of screen sizes, hardware specifications and configurations because of intense competition in mobile software and changes within each of the platforms.[1] Mobile app development has been steadily growing, both in terms of revenues and jobs created. A 2013 analyst report estimates there are 529,000 direct App Economy jobs within the EU 28 members, 60% of which are mobile app developers.
As part of the development process, Mobile User Interface (UI) Design is also an essential in the creation of mobile apps. Mobile UI considers constraints & contexts, screen, input and mobility as outlines for design. The user is often the focus of interaction with their device, and the interface entails components of both hardware and software. User input allows for the users to manipulate a system, and device's output allows the system to indicate the effects of the users' manipulation. Mobile UI design constraints include limited attention and form factors, such as a mobile device's screen size for a user's hand(s). Mobile UI contexts signal cues from user activity, such as location and scheduling that can be shown from user interactions within a mobile application. Overall, mobile UI design's goal is primarily for an understandable, user-friendly interface. The UI of mobile apps should: consider users' limited attention, minimize keystrokes, and be task-oriented with a minimum set of functions. This functionality is supported by Mobile enterprise application platforms or Integrated development environments (IDEs).

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Thursday, 25 June 2015

Mobile computing

Mobile computing is human–computer interaction by which a computer is expected to be transported during normal usage. Mobile computing involves mobile communication, mobile hardware, and mobile software. Communication issues include ad hoc and infrastructure networks as well as communication properties, protocols, data formats and concrete technologies. Hardware includes mobile devices or device components. Mobile software deals with the characteristics and requirements of mobile applications.
Mobile Computing is "taking a computer and all necessary files and software out into the field and the system".[1] There are several different dimensions under which mobile computers can be defined: (1) in terms of physical dimensions; (2) in terms of how devices may be hosted; (3) in terms of when the mobility occurs; (4) in terms of how devices are networked; (5) in terms of the type of computing that is performed. [2]
In terms of dimensions, mobile computers tend to be planar and tend to range in size from centimeters to decimeters. Mobile computer may themselves be mobile, e.g., it is embedded into a Robot or Vehicle that is mobile or itself may not be mobile, but is carried by a mobile host, e.g., the mobile phone is not mobile but it is carried by a mobile human. The most flexible mobile computer is one that can move during its operation or user session but this depends in part on the range of any wireless network it is connected to. A tablet or laptopcomputer connected via Wi-Fi can move while staying connected within the range of its WLAN transmitter. To move between multiple different located WLANs, the device must interrupt, suspend, or close its current user session before connecting to another WLAN transmitter in another session. A device such as a tablet or mobile phone can move much further while staying connected within the range of a GSM network as it can seamlessly move between multiple GSM transmitters or Base stations. Mobile computers may also support or form part of a more local network that moves as the devices, i.e., mobile computers may also be used as part of a Wireless Body Area NetworkWireless Personal Area Network or a piconet. Depending on the type of application the mobile computer runs, the computation of the applications may run only locally, e.g., a PC game. The majority of mobile computers for personal use tends to be used for communication or for remote data downloads such as remote Web access (see Mobile Internet device). As some mobile computers contain an array of sensors, microphones and cameras, these can be used for local data capture, filtering tagging and remote uploads. Increasing mobile computers are also being used to access services such as travel, payment or for access to controlled physical spaces.
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Mobile broadband

Mobile broadband is the marketing term for wireless Internet access through a portable modemmobile phoneUSB wireless modemtablet or other mobile devices. The first wireless Internet access became available in 1991 as part of the second generation (2G) of mobile phone technology. Higher speeds became available in 2001 and 2006 as part of the third (3G) and fourth (4G) generations. In 2011, 90% of the world's population lived in areas with 2G coverage, while 45% lived in areas with 2G and 3G coverage.[1] Mobile broadband uses the spectrum of 225 MHz to 3700 MHz.
Mobile broadband is the marketing term for wireless Internet access delivered through mobile phone towers to computers, mobile phones (called "cell phones" in North America and South Africa), and other digital devices usingportable modems. Although broadband has a technical meaning, wireless-carrier marketing uses the phrase "mobile broadband" as a synonym for mobile Internet access. Some mobile services allow more than one device to be connected to the Internet using a single cellular connection using a process calledtethering.[3]
The bit rates available with Mobile broadband devices support voice and video as well as other data access. Devices that provide mobile broadband to mobile computers include:
Internet access subscriptions are usually sold separately from mobile phone subscriptions.

Mobile ”Best practices"

Best practices” is a loaded term when it comes to creating mobile web experiences. It’s a unique context with it’s own challenges and opportunities. While there’s no silver bullet, this site will help you ask the right questions and help solve problems so you can start creating future-friendly web experiences.
A strong mobile web strategy is an increasingly-important component of planning for the future. It requires careful planning, an understanding of the available tools and most importantly a strong focus on helping your users achieve their goals.

There’s a lot of great frameworks out there to help you make great mobile web sites and apps. Whether or not to use a framework depends on what you’re trying to do with your mobile web project. Be mindful of the differences and advantages/disadvantages of each and find the right fit for your project.
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