MOBILE COMMUNICATIONS

Mobile Communications



Mobile Communications

Introduction

Mobile Computing Architecture

Mobile technologies have evolved in recent years due to reduced growth and laptop (wireless) network. Expanding opportunities to use computers, but is vital problem. Mobile users have to deal with the problems of slowness, but the trunk to face frequent interruptions of wireless connections, as well as limited performance. The requirements for mobile services are stability, bandwidth / cost considerations, integration into family environment, application transparency, security and scalability. Moreover, the few major functions of a mobile computing architecture are mentioned below:

Manage the relationship between the two: Check the lines, the selection of the fittest, watching the line of violation to implement the line and in these cases, after a certain strategy, including attempts to return to the connection.

Line management parameters such as definition of service quality and cost parameters, as compared with the requirements specified by notifying the user in case of problems, and provide a set of alternatives.

Authentication and encryption

Management of the site, including access to resources in a foreign environment and track users when necessary (Tooker, 2000, pp 26).

Source: http://ubicomp.teco.edu/mobile_computing.html

Discussion

Protocols for Mobile Internet

FTP (File Transfer Protocol)

The most common is that individual users using software clients FTP to get programs hosted on servers FTP, typically found in universities, companies, or suppliers on the Internet. To connect to an FTP server requires a software client. The browsers such as Netscape Navigator or Microsoft Explorer often have built programs that act as clients and allow you to take files from a server. To be able to leave files on a server, you need an FTP transfer program (in addition, the server has to allow that user is entitled to leave files). Windows '95 has the FTP command, which can run from the command line.

TFTP (Trivial File Transfer Protocol):

It is extremely simple protocol to transfer files. Is implemented over UDP and lacks most of the features of FTP. The only things you can do is read / write a file from / to a server. It has no means to authenticate users: it is an insecure protocol. Any transfer begins with a request for reading or writing a file. If the server grants the request, the connection is opened and the file is sent in blocks of 512 bytes (fixed length) (Mitchell, 2005, Pp 101). An acknowledgment packet must acknowledge each packet of data before the next can be sent. It assumes the completion of the transfer when a data packet is less than 512 bytes. Almost all errors will cause the termination of the connection (for lack of reliability). If a packet is lost in the network, a timeout will occur after the broadcast of the last packet (data or acknowledgment) took place.

SMTP (Simple Mail Transfer Protocol):

The 'Simple Mail Transfer Protocol'-SMTP-defines the mechanism for moving mail between different machines. There are two involved in this mechanism, the point of origin and the destination of the mail. The origin point opens a TCP connection to the destination. The port used by the receiver is standard on ...