Wireless Communication

Wireless Communication -The transmission of information signals without a physical connection, through technologies such as cordless telephones, cellular telephones or microwave is also defined as the transfer of electromagnetic signals from one location to another without cables, often using infrared light or radio waves. Communication that takes place via airwaves as opposed to cables or telephone lines is known as Wireless Communication.
Wireless means transmitting signals over invisible radio waves instead of wires. Garage door openers and television remote controls were the first wireless devices to become a part of everyday life. Now the cordless keyboard & mouse, PDAs and digital, cellular phones’ are commonplace.



The future of wireless lies in faster, more reliable methods of transferring data and to a increased use of voice commands and audio improvements. A laptop is a mobile device if you had a inclination to carry it around with you. A wireless device has some sort of network connectivity. A cell phone is wireless and a laptop or PDA would be wireless if they had a wireless modem. Similarly an application are wireless when they connect and exchange data with a network.
 

Wireless Communication – Types

Wireless can be divided into following categories:
Fixed Wireless:
The operation of wireless devices or systems in fixed locations, such as homes and offices comes under fixed wireless is known as Fixed Wireless. A example would be equipment connected to the Internet via specialized modems.
Mobile Wireless:
The use of wireless devices or systems in motorized and moving vehicles comes under mobile wireless such as automotive cell phone and personal communication services.
Portable Wireless:
The operation of autonomous, battery powered wireless devices or systems outside the office, home or vehicle comes under portable Wireless. Example: Handheld cell phones.
IR Wireless:
The use of devices that convey data via infrared radiation comes under IR wireless. Example: portable wireless devices that derive their power from batteries.
 

Evolution – Mobile Generation

Mobile Generation – 1G

1G:

• 1G is short for first-generation wireless telephone technology, cell phones. These are the analog cellphone standards that were introduced in the 1980s and continued until being replaced by 2G digital cellphones. The main difference between two succeeding mobile telephone systems, 1G and 2G, is that the radio signals that 1G networks use are analog, while 2G networks are digital.
• Example: AMPS (Advanced Mobile Phone System)

2G:

• 2G is short for second-generation wireless telephone technology. 2G networks are digital.
• Using digital signals between the handsets and the towers increases system capacity in two key ways:
• Digital voice data can be compressed and multiplexed much more effectively than analog voice encodings through the use of various Codec’s, allowing more calls to be packed into the same amount of radio bandwidth.
• The digital systems were designed to emit less radio power from the handsets. This meant that cells could be smaller, so more cells could be placed in the same amount of space. This was also made possible by cell towers and related equipment getting less expensive.

Advantages:

• Digital systems were embraced by consumers for several reasons:
• The lower powered radio signals require less battery power, so phones last much longer between charges, and batteries can be smaller.
• The digital voice encoding allowed digital error checking which could increase sound quality by reducing dynamic and lowering the noise floor.
• The lower power emissions helped address health concerns.
• Going all-digital allowed for the introduction of digital data services, such as SMS and email.

Disadvantages:

• The downsides of 2G systems, not often well publicized, are:
• In less populous areas, the weaker digital signal will not be sufficient to reach a cell tower.
• Analog has a smooth decay curve, digital a jagged steppy one. This can be both an advantage and a disadvantage. Under good conditions, digital will sound better. Under slightly worse conditions, analog will experience static, while digital has occasional dropouts. As conditions worsen, though, digital will start to completely fail, by dropping calls or being unintelligible, while analog slowly gets worse, generally holding a call longer and allowing at least a few words to get through.
• With analog systems it was possible to have two or more “cloned” handsets that had the same phone number. This was widely abused for fraudulent purposes. It was, however, of great advantage in many legitimate situations. One could have a backup handset in case of damage or loss, a permanently installed handset in a car or remote workshop, and so on. With digital systems, this is no longer possible, unless the two handsets are never turned on simultaneously.
• While digital calls tend to be free of static and background noise, the lossy compression used by the CODECs takes a toll; the range of sound that they convey is reduced. You’ll hear less of the tonality of someone’s voice talking on a digital cellphone, but you will hear it more clearly.
• Example: GSM (Global System for Mobile communications)

3G :

• 3G is the third generation of mobile phone standards and technology, superseding 2G. The most significant feature of 3G mobile technology is that it supports greater numbers of voice and data customers — especially in urban areas — and higher data rates at lower incremental cost than 2G. It also allows the transmission of 384 kbit/s for mobile systems and 2 Mb/s for stationary systems. As of 2005, the evolution of the 3G networks was on its way for a couple of years, due to the limited capacity of the existing 2G networks. 2G networks were built mainly for voice data and slow transmission. Due to rapid changes in user expectation, they do not meet today’s wireless needs.
•  2.5 G are technologies such as i-mode data services, camera phones, high-speed circuit-switched data (HSCSD) and General packet radio service (GPRS) were created to provide some functionality domains like 3G networks, but without the full transition to 3G network. They were built to introduce the possibilities of wireless application technology to the end consumers, and so increase demand for 3G services.
• Example: UMTS (Universal Mobile Telecommunications System)

4G :

• 4G is the fourth generation of mobile phone mobile communications standards. It is a successor of the third generation (3G) standards. A 4G system provides mobile ultra-broadband Internet access, for example to laptops with USB wireless modems, to smartphones, and to other mobile devices. Conceivable applications include amended mobile web access, IP telephony, gaming services, high-definition mobile TV, video conferencing and 3D television.