Mobile Databases

·         Recent advances in portable and wireless technology have led to mobile computing, a new dimension in data communication and processing.

·         Portable computing devices coupled with wireless communications allow clients to access data from virtually anywhere and at any time.

·         This feature is especially useful to geographically dispersed organizations.

·         Some of the software problems, which may involve data management, transaction management, and database recovery—have their origins in distributed database systems.

Explanation:

·         It is a distributed architecture where a number of computers, generally referred to as Fixed Hosts (FS) and Base Stations (BS), are interconnected through a high-speed wired network.

·         Fixed hosts are general purpose computers that are not typically equipped to manage mobile units but can be configured to do so.

·         Base stations are Mobile Units' (MU) gateways to the fixed network. They are equipped with wireless interfaces and offer network access services of which mobile units are clients.

Wireless Medium:

·         The wireless medium on which mobile units and base stations communicate have bandwidths significantly lower than those of a wired network.

·         The current generation of wireless technology has data rates that range from the tens to hundreds of kilobits per second (2G cellular telephony) to tens of megabits per second (wireless Ethernet, popularly known as WiFi).

·         Modern (wired) Ethernet, by comparison, provides data rates on the order of hundreds of megabits per second.

·         Besides data rates, other characteristics also distinguish wireless connectivity options. Some of these characteristics include range, interference, locality of access, and support for packet switching.

·         Some wireless access options allow seamless roaming throughout a geographical region (e.g., cellular networks), whereas WiFi networks are localized around a base station.

·         Some networks, such as WiFi and Bluetooth, use unlicensed areas of the frequency spectrum, which may cause interference with other appliances, such as cordless telephones.

·        Finally, modern wireless networks can transfer data in units called packets, which is commonly used in wired networks in order to conserve bandwidth.