Briefly discuss wireless and mobile computing, and various techniques used for wireless and mobile computing.

Wireless computing refers to the method of transferring information between computing devices without a physical connection. For example, transmission between a personal data assistant (PDA), and a data source. Not all wireless communications technologies are mobile. Wireless communication is simply data communication without the use of landlines. The computing device is continuously connected to the base network.

Mobile computing means that the computing device is not continuously connected to the base or central network. Mobile computing does not necessarily require wireless communication. It may not require communication between devices at all.

Various techniques used for wireless and mobile computing are as follows:

1. Global System for Mobile communications (GSM) — GSM uses narrowband TDMA (Time Division Multiple Access), which allows eight simultaneous calls on the same radio frequency. GSM users simply switch subscriber identification module (SIM) cards to access a particular wireless service provider.
2. Code-Division Multiple Access (CDMA) — It uses a spread-spectrum technique where data is sent in small pieces over a number of discrete frequencies. Each user's signal is spread over the entire bandwidth by unique spreading code. At the receiver end, the same unique code is used to recover the signal.
3. Wireless in Local Loop (WLL) — WLL is a system that connects subscribers to the public switched telephone network (PSTN) using radio signals as a substitute for other connecting media.
4. General Packet Radio Service (GPRS) — It is a technology for radio transmission of small packets of data especially between mobile devices and Internet.
5. First Generation (1G) — 1G networks were conceived and designed purely for voice calls with almost no consideration of data services.
6. Second Generation (2G) — They offered improved sound quality, better security and higher total capacity.
7. Third Generation (3G) — 3G mobile communications technology is a broad­ band, packet-based transmission of text, digitized voice, video, and multimedia at data rates up to and possibly higher than 2 megabits per second (Mbps), offering a consistent set of services to mobile computer and phone users no matter where they are located in the world.
8. Fourth Generation (4G) — 4G is a Mobile multimedia, Network System with anytime anywhere Global mobility support, integrated wireless solution, and Customized Personal Service.
9. Fifth Generation (5G) — 5G networks promise to provide speeds of upto 100 gigabits per second. 5G is set to be 40 to 100 times faster than 4G networks.