05-10-2016, 04:10 PM
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DEFINITION
Mobile computing is a generic term describing one's ability to use technology while moving, as opposed to portable computers, which are only practical for use while deployed in a stationary configuration. Many types of mobile computers have been introduced since the 1990s, including the: Wearable computer Personal digital assistant /Enterprise digital assistant Smart phone Carputer UMPC Pocket PC
Limitations of mobile computing :
Limitations of mobile computing Insufficient bandwidth Security standards Power consumption Transmission Interferences Potential Health Hazards Human Interface with devices
Goal of Wireless and Mobile Computing :
Goal of Wireless and Mobile Computing “People and their machines should be able to access information and communicate with each other easily and securely, in any medium or combination of media –voice, data, image, video, or multimedia –anytime, anywhere, in a timely, cost-effective way.”
What is Mobility?:
What is Mobility? A person who moves Between different geographical locations Between different networks Between different communication devices Between different applications A device that moves Between different geographical locations Between different networks
MOBILE COMPUTING & AUTOMATIC CHARGING
(HOW MUCH YOU TALK YOUR MOBILE WILL BE CHARGED ACCORDINGLY )
Wireless Charging Of Mobile Phones Using Microwaves (solar charging)
With mobile phones becoming a basic part of life, the recharging of mobile phone batteries has always been a problem. The mobile phones vary in their talk time and battery standby according to their manufacture and batteries. All these phones irrespective of their manufacturer and batteries have to be put to recharge after the battery has drained out.
The main objective of this current proposal is to make the recharging of the mobile phones independent of their manufacturer and battery make. In this paper a new proposal has been made so as to make the recharging of the mobile phones is done automatically as you talk in your mobile phone! This is done by use of microwaves. The microwave signal is transmitted from the transmitter along with the message signal using special kind of antennas called slotted wave guide antenna at a frequency is 2.45 GHz.
There are minimal additions, which have to be made in the mobile handsets, which are the addition of a sensor, a Rectenna, and a filter. With the above setup, the need for separate chargers for mobile phones is eliminated and makes charging universal. Thus the more you talk, the more is your mobile phone charged! With this proposal the manufacturers would be able to remove the talk time and battery stand by from their phone specifications.
Introduction of Wireless Charging Of Mobile Phones Using Microwaves
The basic addition to the mobile phone is going to be the rectenna. A rectenna is a rectifying antenna, a special type of antenna that is used to directly convert microwave energy into DC electricity.
Its elements are usually arranged in a mesh pattern, giving it a distinct appearance from most antennae. A simple rectenna can be constructed from a Schottky diode placed between antenna dipoles. The diode rectifies the current induced in the antenna by the microwaves.
Rectenna are highly efficient at converting microwave energy to electricity. In laboratory environments, efficiencies above 90% have been observed with regularity. Some experimentation has been done with inverse rectenna, converting electricity into microwave energy, but efficiencies are much lower--only in the area of 1%. With the advent of nanotechnology and MEMS the size of these devices can be brought down to molecular level.
It has been theorized that similar devices, scaled down to the proportions used in nanotechnology, could be used to convert light into electricity at much greater efficiencies than what is currently possible with solar cells. This type of device is called an optical rectenna.
Theoretically, high efficiencies can be maintained as the device shrinks, but experiments funded by the United States National Renewable energy Laboratory have so far only obtained roughly 1% efficiency while using infrared light. Another important part of our receiver circuitry is a simple sensor.
Receiver Design :
The basic addition to the mobile phone is going to be the rectenna. A rectenna is a rectifying antenna, a special type of antenna that is used to directly convert microwave energy into DC electricity.
Rectifies received microwaves into DC current a rectenna comprises of a mesh of dipoles and diodes for absorbing microwave energy from a transmitter and converting it into electric power. Its elements are usually arranged in a mesh pattern, giving it a distinct appearance from most antennae. A simple rectenna can be constructed from a Schottky diode placed between antenna dipoles as shown in Fig...
The diode rectifies the current induced in the antenna by the microwaves. Rectenna are highly efficient at converting microwave energy to electricity.
In laboratory environments, efficiencies above 90% have been observed with regularity. In future rectennass will be used to generate large-scale power from microwave beams delivered from orbiting SPS satellites.
The sensor circuitry is a simple circuit, which detects if the mobile phone receives any message signal. This is required, as the phone has to be charged as long as the user is talking. Thus a simple F to V converter would serve our purpose. In India the operating frequency of the mobile phone operators is generally 900MHz or 1800MHz for the GSM system for mobile communication.
GSM (Global System using Mobile computing)
GSM (Global System for Mobile communication) is a digital mobile telephony system that is widely used in Europe and other parts of the world. GSM uses a variation of time division multiple access (TDMA) and is the most widely used of the three digital wireless telephony technologies (TDMA, GSM, and CDMA). GSM digitizes and compresses data, then sends it down a channel with two other streams of user data, each in its own time slot. It operates at either the 900 MHz or 1800 MHz frequency band.
Mobile services based on GSM technology were first launched in Finland in 1991. Today, more than 690 mobile networks provide GSM services across 213 countries and GSM represents 82.4% of all global mobile connections. According to GSM World, there are now more than 2 billion GSM mobile phone users worldwide. GSM World references China as "the largest single GSM market, with more than 370 million users, followed by Russia with 145 million, India with 83 million and the USA with 78 million users."
Since many GSM network operators have roaming agreements with foreign operators, users can often continue to use their mobile phones when they travel to other countries. SIM cards (Subscriber Identity Module) holding home network access configurations may be switched to those will metered local access, significantly reducing roaming costs while experiencing no reductions in service.
GSM, together with other technologies, is part of the evolution of wireless mobile telemmunications that includes High-Speed Circuit-Switched Data (HSCSD), General Packet Radio System (GPRS), Enhanced Data GSM Environment (EDGE), and Universal Mobile Telecommunications Service (UMTS).
Mobile satellite services
Mobile satellite services are set to change with the imminent launch of satellite personal communication services (S-PCS), through the use of non-geostationary satellites. This new generation of satellites will be placed in low earth orbit or medium earth orbit, hence, introducing new satellite design concepts. One of the first texts to cover this rapidly evolving field, this text provides the reader with an overview of mobile satellite systems, from their initial introduction (Inmarsat), current satellite-PCS (referring to such systems as Globalstar), through to Satellite-UMTS and an understanding of the following:
* The design concepts associated with non-geostationary satellite systems (constellation, link budgets, Doppler)
* The concepts of UMTS (network architecture, aims, in the context of IMT-2000) and the role foreseen for the satellite component (complementary to terrestrial network, network extension, global availability)
* Inter-working between satellite and terrestrial networks (network architecture, ATM Adaptation Layer)
* Radio interface technologies (WB-CDMA, TDMA, transmission environment)
* Regulatory issues
* Future services and applications