What is 3G?
The third generation of wireless telecommunication technology is known as 3G. (First generation of wireless telecommunication technology is known as analog cellular, Second generation of wireless telecommunication technology is known as Digital PCS). Third generation of wireless telecommunication technology is a combination of wireless communication and Internet. 3G has super imposed the lower generations of wireless telecommunication technology in terms of design (same design is used world wide), compatible service, use of small terminals which supports Internet , Multi Media Access and Roaming. 3G is mainly used in Mobile. Using 3G technologies network operators can provide wide range of advanced services to the user with higher speed. User can now surf the internet , upload or download the data , make video call , audio and video streaming , use GPS (Global Positioning System), video conferencing at the blink of eye using 3G technologies. 3G supports IPTV (TV through the Internet) too. Using 3G in Fixed Wireless Lans data can be transferred at the speed of 5-8 Mb per second, whereas for moving device the speed may decrease. A device supporting 3G can work as computer, Television, Newspaper, ipod, Dairy, credit card etc. Using 3G technology our mobile just works like a mini computer supporting multitasking (supports different services at the same time on a same device).
What is 3G Technology?
3G the third generation of wireless telecommunication technology has given a new dimension to telecommunication industry with data transmission at lighting fast speed, more digital clarity and various multimedia services. 3G technology has made our mobile work just like a mini computer with large number of mobile applications. User can now surf the internet , upload or download the data , make video call , audio and video streaming , use GPS (Global Positioning System) at the blink of eye using 3G technologies . The main aim of 3G services is to provide user with highest speed for Data and voice transfers, GPS and other applications in secure manner. In 3G services the transmitted data is in the encrypted format only the end users can decrypt the data hence providing security to the transmitted information. 3G technology is able to provide many services because it consists of large number of Radio Technologies. 3G mostly uses CDMA and TDMA methods; FDMA is only used in DECT. According to IMT-2000 standard the following technologies can be called as 3G Technology. Code Division Multiple Access 2000 (CDMA 2000) named as IMT Multicarrier (IMT-MC) in IMT-2000 standard,Time Division Synchronous Code Division Multiple Access (TD-SCDMA) named as IMT Time Code (IMT-TC) in IMT-2000 standard, Universal Mobile Telecommunications Services (UMTS) also known as Wideband Code Division Multiple Access (W-CDMA) named as IMT Direct Spread (IMT-DS), UWC-136 named as IMT Single Carrier (IMT-SC) and Digital enhanced cordless telecommunications (DECT) named as IMT Frequency Time (IMT-FT).
Code Division Multiple Access 2000(CDMA 2000) was used to move from 2G to 3G in an efficient manner in North America. As Code Division Multiple Access 2000(CDMA 2000) is backward compatible it was easier for the providers to deploy CDMA 2000 and IS-95 in the same frequency band at the same instance of time.CDMA2000 operates on synchronous network; using synchronous network results in greater efficiency which attracted the GSM Operators. These operators were interested in utilizing an efficient network so they used CDMA2000 instead of upgrading to any other technology. Code Division Multiple Access 2000 (CDMA 2000) is used to get highest speed for data transfers with more efficiency.
Universal Mobile Telephony System (UMTS) also known as Wideband Code Division Multiple Access (W-CDMA) uses a minimum bandwidth of 5 MHz; since 5 MHz is sufficient to transmit with data rates of 144 to 384 Kbps. WCDMA provides total control on uplink and downlink i.e. can vary the data rate .WCDMA can also transmit at a data rate up to 2Mbps.This was mostly used in Europe as some frequency bands can either be used for uplink or downlink (paired bands) or both using timesharing (unpaired bands). WCDMA consist of two modes Frequency Division Duplex for paired bands and time division duplex for unpaired bands. This technology was more expensive for network operators than others as it requires new infrastructure and WCDMA is very Complex.
Time Division Synchronous Code Division Multiple Access (TD-SCDMA) was proposed by china. Time Division Synchronous Code Division Multiple Access (TD-SCDMA is a narrow frequency carrier system. And this feature of Time Division Synchronous Code Division Multiple Access (TD-SCDMA) attracts the operators as it contributes to more frequencies available for the operator. This is most fruitful for the operators with small spectrum allocations. It also increases the system (network operator system) capacity to handle more users at the same time. As name indicates Time Division Synchronous Code Division Multiple Access (TD-SCDMA) uses time division duplex system. This system can easily handle asymmetric traffic with different data rates on uplink and downlink by adjusting the timeslots for uplink and downlink. Here the uplink signals are time synchronized at base station resulting in minimum interference among the users at the same timeslot differentiated by various codes and hence increasing the capacity of the network operator system. The only disadvantage is that this system has complex hardware in order to attain uplink synchronization.
UWC-136 system also known as IMT- SC is based on Time Division Multiple Access technology and is compatible with IS-136 standard. It uses carrier of 30 KHz, 200 KHz and 1.6 MHz. The carrier of 30 KHz is compatible with IS-136. The carrier of 200 KHz transmits data at the speed upto 384 Kbps and has similar parameters as that of EDGE and GSM. This was mainly used by traffic outdoors. The carrier of 1.6 MHz transmits data at the speed upto 2 Mbps and was used as indoor.
Digital enhanced cordless telecommunications (DECT) as name indicates is the digital radio access standard for cordless communication which was developed by ETSI. The main concentration of this system was on ISDN access and telephony. This system is mainly used in small business system, corporate offices, residential systems and public cordless access systems. It is reliable and can be used in any environment it can also be used in underground mines. It works on the 1880-1900 MHz band in Europe While in other countries it uses 1900-1930 band. The band used is divided to form ten carrier frequencies and each frequency is divided to form 23 slots (time slot). Any two time slots are selected and used for communication. DECT uses TDMA/FDMA\TDD techniques. DECT provides various services like voice service, fax service, data service and multimedia service with the help of various DECT profiles. It also provides text messaging, two way communication, alarms, place locator, third party interfacing etc. With large number of features, secure communication and better voice calls DECT has become very popular around the world. On this system we can use various products like answering machines, menu driven handsets with user interface or cordless adapters. This system selects and allocates the channel dynamically and use of Time division duplex radio access method results in use of cellular systems even if they are in busy environment. Because of using the above techniques DECT can be used in various systems.
1) Introduction To 3G Mobile Communication – By Juha Korhonen
2)Wireless Networks – By P. Nicopolitidis
3) Voice & Data Communication Handbook – By Regis J. Bates, Donald W. Gregory