Mobile computing is the discipline for creating an information management platform, which is free from spatial and temporal constraints. The freedom from these constraints allows its users to access and process desired information from anywhere in the space.The state of the user, static or mobile, does not affect the information management capability of the mobile platform. A user can continue to access and manipulate desired data while traveling on plane, in car, on ship, etc. Thus, the discipline creates an illusion that the desired data and sufficient rocessing power are available on the spot, where as in reality they may be located far away.
The discipline of mobile computing has its origin in Personal Communications Services (PCS). PCS refers to a wide variety of wireless access and personal mobility services provided through a small terminal (e.g., cell phone), with the goal of enabling communications at any time, at any place, and in any form. PCS are connected to Public Switched Telephone Network (PSTN) to provide access to wired telephones. PCS include high-tier digital cellular systems for idespread vehicular and pedestrian services and low-tier telecommunication system standards for residential, business, and public cordless access applications
High-tier digital cellular systems include
Global System for Mobile Communications (GSM)
IS-136 TDMA based Digital Advanced Mobile Phone Services (DAMPS)
Personal Digital Cellular (PDC)
IS-95 CDMA-based cdmaOne System
Low-tier telecommunication systems include
Cordless Telephone 2 (CT2)
Digital Enhanced Cordless Telephone (DECT)
Personal Access Communication Systems (PACS)
Personal Handy Phone Systems (PHS)
Several wideband wireless systems and special data systems have been developed to accommodate internet and multimedia services. We do not include these specialized systems in this course. We will discuss in detail all essential aspects of PCS and use this platform to introduce the discipline of mobile computing. However, from now on we will always use the term mobile computing in our iscussion. In mobile computing platform information between processing units flows through wireless channels. The processing units (client in client/server paradigm) are free from temporal and spatial constraints. That is, a processing unit (client) is free to move about in the space while being connected to the server. This temporal and spatial freedom provides a powerful facility allowing users to reach the data site (site where the desired data is stored) and the processing site (the geographical location where a processing must be performed) from anywhere. This capability allows organizations to set their offices at any location. It is interesting to learn some of the historical milestones achieved in mobile systems, which appeared some time ago. The events can be listed as follows:
April 7, 1928: The first mobile radio system went into operation in Detroit. It was used by the Detroit Police Department.
Year 1935: Frequency modulation has been developed and tested.
Year 1943: AT&T developed and introduced the Improved Mobile Telephone Service (IMTS). It consisted of a broadcast system with a higher-power transmitter. This system was followed shortly with limited cellular networks and the implementation of the first mobile radio system to connect with a fixed telephone number.
Year 1950s: Paging systems began to appear. During this period, Bell Labs continued to test the cellular techniques.
Year 1970: Federal Communication Commission (FCC) allocated spectrum space for cellular systems. At this time, AT&T proposed the cellular system that is now known as the Advanced Mobile Phone System (AMPS).
Year 1983: The cellular service was commercially implemented in Chicago and Baltimore.
To facilitate the data management activities, users can carry Personal Digital Assistant (PDA), laptop, cell phones, etc. At present the current technology only provides limited transaction processing capabilities but soon such facilities will be available on all mobile devices such as cell phones, laptops, palmtops, etc. This discipline allows us to define a connectivity mode, which we refer to as "Mobile Connectivity".
Year 1935: Frequency modulation has been developed and tested.
Year 1943: AT&T developed and introduced the Improved Mobile Telephone Service (IMTS). It consisted of a broadcast system with a higher-power transmitter. This system was followed shortly with limited cellular networks and the implementation of the first mobile radio system to connect with a fixed telephone number.
Year 1950s: Paging systems began to appear. During this period, Bell Labs continued to test the cellular techniques.
Year 1970: Federal Communication Commission (FCC) allocated spectrum space for cellular systems. At this time, AT&T proposed the cellular system that is now known as the Advanced Mobile Phone System (AMPS).
Year 1983: The cellular service was commercially implemented in Chicago and Baltimore.
To facilitate the data management activities, users can carry Personal Digital Assistant (PDA), laptop, cell phones, etc. At present the current technology only provides limited transaction processing capabilities but soon such facilities will be available on all mobile devices such as cell phones, laptops, palmtops, etc. This discipline allows us to define a connectivity mode, which we refer to as "Mobile Connectivity".
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