THE G FAMILY : PART 2

2.5 G
2.5G is a stepping stone between 2G and 3G cellular wireless technologies. The term "second and a half generation" is used to describe 2G-systems that have implemented a packet switched domain in addition to the circuit switched domain. 2.5G provides some of the benefits of 3G (e.g. it is packet-switched) and can use some of the existing 2G infrastructure in GSM and CDMA networks. GPRS is a 2.5G technology used by GSM operators
3G
International Mobile Telecommunications-2000 (IMT-2000), better known as 3G or 3rd Generation, is a family of standards for mobile telecommunications defined by the International Telecommunication Union, which includes GSM EDGE, UMTS, and CDMA2000 as well as DECT and WiMAX. Services include wide-area wireless voice telephone, video calls, and wireless data, all in a mobile environment. Compared to 2G and 2.5G services, 3G allows simultaneous use of speech and data services and higher data rates (up to 14.0 Mbit/s on the downlink and 5.8 Mbit/s on the uplink with HSPA+). Thus, 3G networks enable network operators to offer users a wider range of more advanced services while achieving greater network capacity through improved spectral efficiency.
The new services which we will get from 3g are Fast Communication, Internet, Mobile T.V, Video Conferencing, Video Calls, Multi Media Messaging Service (MMS), 3D gaming, Multi-Gaming etc
TERMS TO GET CLEAR
NARROW BAND AND WIDE BAND
2G OPERATES IN NARROW BAND AND > 3G OPERATES IN WIDE BAND
Wireless systems can be classified according to whether they have a narrowband or wideband architecture. Narrowband systems support low-bit-rate transmission, whereas wideband systems support high-bit-rate transmission. A system is defined as narrowband or wideband depending on the bandwidth of the transmission physical channels with which it operates
The coherence bandwidth is defined as the frequency band within which all frequency components are equally affected by fading due to multipath propagation phenomena. Systems operating with channels substantially narrower than the coherence bandwidth are known as narrowband systems. Wideband systems operate with channels substantially wider than the coherence bandwidth. In narrowband systems, all the components of the signal are equally influenced by multipath propagation. Accordingly, although with different amplitudes, the received narrowband signal is essentially the same as the transmitted narrowband signal. In wideband systems, the various frequency components of the signal may be differently affected by fading.
In wireless telecommunications, multipath is the propagation phenomenon that results in radio signals reaching the receiving antenna by two or more paths. Causes of multipath include atmospheric ducting, ionospheric reflection and refraction, and reflection from water bodies and terrestrial objects such as mountains and buildings. The effects of multipath include constructive and destructive interference, and phase shifting of the signal. This causes Rayleigh fading.

THE G FAMILY : 0G 1G 2G 2.5G 3G , PART 1

In this article I am going to give a brief intro of G family , i.e 0G 1G 2G 3G , how they work and later economics related with 3G auction in india.
0G
The 0G or early mobile telephone systems can be distinguished from earlier closed radiotelephone systems in that they were available as a commercial service that was part of the public switched telephone network, with their own telephone numbers,rather than part of a closed network such as a police radio or taxi dispatch system.
These mobile telephones were usually mounted in cars or trucks, though briefcase models were also made. Typically, the transceiver (transmitter-receiver) was mounted in the vehicle trunk and attached to the "head" (dial, display, and handset) mounted near the driver seat.
IMTS AND RCC were the technlogy which were used. In public switched network, suppose two caller wants to talk , then the operator of respective caller will secure a common line and let them talk , and till these users don't end their talk the line will remain busy.
1G
1G (or 1-G) refers to the first-generation of wireless telephone technology, mobile telecommunications. These are the analog telecommunications standards that were introduced in the 1980s.
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.Although both systems use digital signaling to connect any two radio towers (which listen to the handsets),but to the rest of the telephone system, the voice itself during a call is encoded to digital signals in 2G whereas 1G is only modulated to higher frequency, typically 150MHz and up.
technologies used AMPS,NMT,RTMI and TACS
2G
Started in 1991 , it has three primary benefits over their predecessors ,that phone conversations were digitally encrypted, 2G systems were significantly more efficient on the spectrum allowing for far greater mobile phone penetration levels; and 2G introduced data services for mobile, starting with SMS text messages.
2G technologies can be divided into TDMA-based and CDMA-based standards. GSM is TDMA based, therefore we generally hears only about cdma and gsm phones.Also a third technolgy is FDMA which is generally used in combination with these
0G 1G AND 2G ALL WERE CIRCUIT SWITCH NETWORKS
TERMS TO GET CLEAR
1 CIRCUIT SWITCHING AND PACKET SWITCHING
In packet switching , the users data is grouped into packets of definite sizes generally in bytes . it is these packets which have to be switched between users ,whereas in circuit a definite route or resource or path is held by users ,and these are switched. we can take a example of trains to understand it . Suppose there are three parallel tracks , in case of CS the train will run over them ,so only three users can be connected at a time , whereas in PS ,the coaches of train are considered as packets , so more users can connect at a time ,as each train has number of coaches which are reserved by users
2 CDMA TDMA FDMA
FDMA stands for frequency division multiple access , we know that mobile works within a given spectrum ,which is range of frequency ,in FDMA it is divided b/w users , like a highway is divided into lans , but here on a lan one user at a time
TDMA stands for time division multiple access , it can be best understood by considering the that on the lans described in FDMA , we are setting a time interval of users that is from morning 9 to 11 mr sharma on lan 1 , from 11 to 12 mr bhaskar on lan 1 . but as you can see even now road is not fully utilise and idle times are present in between
CDMA stands for code division multiple access , it is little bit difficult to understand as in it we have to consider that the lan sizes can change with the car being use i e code , so what hapens is that depending whether a cycle is coming or truck is coming we can change lan size , that this is also what happens on roads , but like roads the fear of losing packets or accidents increases with increase in number of users