Pervasive Computing

1. INTRODUCTION

Pervasive computing environments involve the interaction, coordination, and cooperation of numerous, casually accessible, and often invisible computing devices. These devices will connect via wired and wireless links to one another as well as to the global networking infrastructure to provide more relevant information and integrated services. Existing approaches to building distributed applications, including client/server computing, are ill suited to meet this challenge. They are targeted at smaller and less dynamic computing environments and lack sufficient facilities to manage changes in the network configurations. Networked computing devices will proliferate in the user's landscape, being embedded in objects ranging from home appliances to clothing. Applications will have greater awareness of context, and thus will be able to provide more intelligent services that reduce the burden on users to direct and interact with applications. Many applications will resemble agents that carry out tasks on behalf of users by exploiting the rich sets of services available within computing environments.

Mobile computing and communication is one of the major parts of the pervasive computing system. Here data and computing resources are shared among the various devices. The coordination between these devices is maintained through communication, which may be wired or wireless. With the advent of Bluetooth and Ad hoc networking technologies the wireless communication has overtaken the wired counterpart.

The reduction in size and cost of processor chips made it possible to implement it in every field of life. Nowadays about 99% of processors made are for embedded devices compared to the PC applications. Voice and Gesture recognition along with steerable interface will make the interactions and use of these devices more users friendly. Efficient security and privacy policies along with power management can enhance the performance of such systems.

2. CURRENT EMBEDDED TECHNOLOGY

Embedded technology is the process of introducing computing power to various appliances. These devices are intended to perform certain specific jobs and processors giving the computing power are designed in an application oriented way. Computers are hidden in numerous information appliances which we use in our day to day life. These devices find their application in every segment of life such as consumer electronics, avionics, biomedical engineering, manufacturing, process control, industrial, communication, defence etc...

Embedded systems, based on their functionality and performance requirement are basically categorized as:

i. Stand alone systems

ii. Real time systems

iii. Networked systems

iv. Mobile devices

Stand alone systems work in stand alone mode, taking inputs and producing desired outputs. They do not have any dependence on other systems. Embedded systems in which some specific work has to be done in a specific time period are called Real time systems. Meeting the dead line is the most important requirement of a real time system. In Hard real time systems, missing a deadline may lead to a catastrophe and in Soft real time systems such problem is not present. Systems which are provided with network interfaces and accessed by networks such as LAN or the Internet are called Networked Systems. Networking may be wired or wireless. Mobile devices are devices which move from one location to another, like mobile phones, PDA'S etc.

Today, many people carry numerous portable devices, such as laptops, mobile phones, PDAs and mp3 players, for use in their professional and private lives. For the most part, these devices are used separately i.e., their applications do not interact. However, if they could interact directly, participants at a meeting could share documents or presentations, business cards would automatically find their way into the address register on a laptop and the number register on a mobile phone, as commuters exit a train, their laptops could remain online; likewise, incoming email could now be diverted to their PDAs.

In such a distributed environment where several embedded devices has to communicate and co-ordinate with each other. For this a communication link is required which may be wired or wireless. In initial stages of Networked embedded system environments wired connection was preferred as it provided a safer and faster channel for communication. But the cost, immovability and the cables running around the floorboards became less attractive. On top of this, dishing out the cash for network cards, cables and a hub/switch reserved this practice to the more elite computer users, until wireless networking hit the scene.

Infrared communication was initially used for wireless communication because of the low cost offered by it. But it suffered from the limitation that it can be used only within Line Of Sight. IEEE introduced 802.11 as the international standard for wireless LANs. This used a 2.4GHz transmission band while maintaining a steady 1-2 Mbps bandwidth rate. Being that this was extremely slow compared to 100Mbit wired LANs, it took a while for the 802.11 standard to develop into a viable solution, achieved shortly after with the 802.11a, b and g standards, offering bandwidth ranging from 11Mbps to 54Mbps. Although this is still considerably short of the 100Mbit found in cabled networks, 802.1 x wireless technologies is now literally regarded as the future of networking. Bluetooth, Wi-Fi, Wi-Max are the latest solutions, under the 802.1x standard, for wireless communication over short, medium and long range communication respectively.

3. UBIQUITOUS PERVASIVE COMPUTING

Pervasive computing can be explained in two different perspectives:

i. User view

ii. Technology view

3.1User view

For an end user Pervasive approach act as a method of augmenting human abilities in context of tasks. It provides Interaction transparency which means that the human user is not aware that there is a computer embedded in the tool or device that he or she is using.

3.2Technological view

It means access to information and software applications are available everywhere and anywhere. Technically pervasive computing involves in embedding intelligence and computing power to devices

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