Mobile Adhoc Network

A mobile ad hoc network (MANET), is a self-configuring infra structureless network of mobile devices connected by wireless links. ad hoc is Latin and means "for this purpose".
Each device in a MANET is free to move independently in any direction, and will therefore change its links to other devices frequently. Each must forward traffic unrelated to its own use, and therefore be a router. The primary challenge in building a MANET is equipping each device to continuously maintain the information required to properly route traffic. Such networks may operate by themselves or may be connected to the larger Internet.
MANETs are a kind of wireless ad hoc networks that usually has a routeable networking environment on top of a Link Layer ad hoc network.
The growth of laptops and 802.11/Wi-Fi wireless networking have made MANETs a popular research topic since the mid 1990s. Many academic papers evaluate protocols and their abilities, assuming varying degrees of mobility within a bounded space, usually with all nodes within a few hops of each other. Different protocols are then evaluated based on measure such as the packet drop rate, the overhead introduced by the routing protocol, end-to-end packet delays, network throughput etc.

Voice Over Internet Protocol

Voice over Internet Protocol (Voice over IP, VoIP) is one of a family of internet technologies, communication protocols, and transmission technologies for delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. Other terms frequently encountered and often used synonymously with VoIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony, and broadband phone.
Internet telephony refers to communications services—Voice, fax, SMS, and/or voice-messaging applications—that are transported via the Internet, rather than the public switched telephone network (PSTN). The steps involved in originating a VoIP telephone call are signaling and media channel setup, digitization of the analog voice signal, encoding, packetization, and transmission as Internet Protocol (IP) packets over a packet-switched network. On the receiving side, similar steps (usually in the reverse order) such as reception of the IP packets, decoding of the packets and digital-to-analog conversion reproduce the original voice stream. Even though IP Telephony and VoIP are terms that are used interchangeably, they are actually different; IP telephony has to do with digital telephony systems that use IP protocols for voice communication while VoIP is actually a subset of IP Telephony. VoIP is a technology used by IP telephony as a means of transporting phone calls.
VoIP systems employ session control protocols to control the set-up and tear-down of calls as well as audio codecs which encode speech allowing transmission over an IP network as digital audio via an audio stream. The codec used is varied between different implementations of VoIP (and often a range of codecs are used); some implementations rely on narrowband and compressed speech, while others support high fidelity stereo codecs.
There are three types of VoIP tools that are commonly used; IP Phones,Software VoIP and Mobile and Integrated VoIP. The IP Phones are the most institutionally established but still the least obvious of the VoIP tools. Of all the software VoIP tools that exist, Skype is probably the most easily identifiable. The use of software VoIP has increased during the global recession as many persons, looking for ways to cut costs have turned to these tools for free or inexpensive calling or video conferencing applications. Software VoIP can be further broken down into three classes or subcategories; Web Calling, Voice and Video Instant Messaging and Web Conferencing. Mobile and Integrated VoIP is just another example of the adaptability of VoIP. VoIP is available on many smartphones and internet devices so even the users of portable devices that are not phones can still make calls or send SMS text messages over 3G or WIFI.

Cloud Computing

Cloud computing refers to the provision of computational resources on demand via a computer network, such as applications, databases, file services, email, etc. In the traditional model of computing, both data and software are fully contained on the user's computer; in cloud computing, the user's computer may contain almost no software or data (perhaps a minimal operating system and web browser only), serving as little more than a display terminal for processes occurring on a network of computers far away. A common shorthand for a provided cloud computing service (or even an aggregation of all existing cloud services) is "The Cloud".
The most common analogy to explain cloud computing is that of public utilities such as electricity, gas, and water. Just as centralized and standardized utilities free individuals from the difficulties of generating electricity or pumping water, cloud computing frees users from certain hardware and software installation and maintenance tasks through the use of simpler hardware that accesses a vast network of computing resources (processors, hard drives, etc.). The sharing of resources reduces the cost to individuals.
The phrase “cloud computing” originated from the cloud symbol that is usually used by flow charts and diagrams to symbolize the internet. The principle behind the cloud is that any computer connected to the internet is connected to the same pool of computing power, applications, and files. Users can store and access personal files such as music, pictures, videos, and bookmarks or play games or use productivity applications on a remote server rather than physically carrying around a storage medium such as a DVD or thumb drive. Almost all users of the internet may be using a form of cloud computing though few realize it. Those who use web-based email such as Gmail, Hotmail, Yahoo, a Company owned email, or even an e-mail client program such as Outlook, Evolution, Mozilla Thunderbird or Entourage are making use of cloud email servers. Hence, desktop applications which connect to cloud email would be considered cloud applications.

cache memory

A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations. As long as most memory accesses are cached memory locations, the average latency of memory accesses will be closer to the cache latency than to the latency of main memory.
When the processor needs to read from or write to a location in main memory, it first checks whether a copy of that data is in the cache. If so, the processor immediately reads from or writes to the cache, which is much faster than reading from or writing to main memory.
Most modern desktop and server CPUs have at least three independent caches: an instruction cache to speed up executable instruction fetch, a data cache to speed up data fetch and store, and a translation lookaside buffer (TLB) used to speed up virtual-to-physical address translation for both executable instructions and data. Data cache is usually organized as a hierarchy of more cache levels (L1, L2, etc.; see Multi-level caches).