Standard UMTS

1) IMT 2000 and allocation of the band:

IMT 2000 is a standardization for the cellular systems of third generation, is constituted from a family of standards that find application in various areas of the world, ovunque uses but one band comprised around to the 2GHz.

For Europe the standard is called UMTS and previews one land member and one member to satellitare , it is not joints to a true one and just standards in how much as an example for the UMTS come implemented are solution FDD that gives place to the W-CDMA that that TDD that gives place to the TD-CDMA, first more adapted to the connections voice and the second one more adapted to the typical asymmetric connections of Internet.

 

2) Requirement of service for a system 3G:

to)       the system ability it does not have to be inferior to that one of the systems of 2ª generation

b)       total cover obtained for means of the member to satellitare

c)       variable binary rhythms

d)       tariffazione based on the volume rather than on the time

 

3) Architecture interface radio:

There are 3 layers, the physical layer is to level 1 while the control layer is to level 2 and it subdivides in layer MAC (…control of the access to means) and RLC (…control of the radio duct) then is the layer of net to level 3.

 

4) Typology of channels:

There are the physical channels uses you for the transport of the numerical flow in physical means and the transport channels use you from the physical layer in order to supply services to the advanced layers. The modalities in which the physical channels they are associate to you to the transport channels are various in the TDD and FDD case.

 

5) Structure weft UMTS:

There is a composed superweft from 72 wefts, every hard weft 10ms and contains 15 Time slot every compound from 2560chip for chip-installments total of 3,84Mbit/s.

 

6) physical Layer FDD/W-CDMA:

To every physical channel of the cell it comes associated a code, we have two physical channels for the logons of customer, the DPDCH (Dedicated Given Phisical Channel) for the data of customer and the DPCCH (Dedicated Phisical Control Channel) for the associate signallings.

to)       draft in climb

To DPDCH the various one regarding that Q comes associated a canalization code that comes associated to the DPCCH. They are codes to tree OVSF (Orthogonal Variable Spreading Factor) that they guarantee the ortogonalità also in the case of channels with different binary rhythms. Beyond to these codes it comes then carried out unoscrambling that it is typical of the determined customer.

b)       draft in reduction

Every logon is characterized from a various code of canalization, marks assigns them to the various customers comes before sincronizza you subsequently comes on they executed the operation of scrambling by means of various sequences from cell cell.

For both the drafts then harmonic modulation is previewed one.

 

7) physical Layer TDD/TD-CDMA:

Every slot it can be attributed indifferently to the uplink or to downlink moreover the 16 various logons they can be multiplate in the same one, to ciascuna of they is associated a various code OVSF (Orthogonal Variable Spreading Factor).

The physical channel consists in a slot that it is repeated to regular intervals of time. The attribution of a physical channel to a determined customer consists in the attribution of the slot and the weft of departure.

Beyond to the canalization code that it characterizes the channel then has also a code of scrambling that it characterizes the cell.

 

8) Infrastructure of net:

The really innovative part is the interface radio that takes to the name of UTRAN (UMTS Terrestrial Radio Access Network), it is constituted from the B NODES that carry out the logon with finish them mobile and that these are connected to a RNC (Radio Network Controller) are connected are between of they that towards the fixed net, is commutata it in the which case is passed for a MSC that to package in the which case is passed for a SGSN (Serving GPRS Support Node) which then Gateway GPSR Support Node is connected to a GGSN ().

 

9) Procedure of handover:

The handover in atmosphere UMTS it tries to reduce the probability of interruption of the communication, it can be due is to indisponibilità of resource radio near the cell in which it is arrived or to indisponibilità to connect itself to the fixed net of the same cell, those that is made therefore is to connect between they the BTS by means of fixed net, when the handover happens between two cells, takes advantage of the connection to the net of the BTS origin and it is connected to the destinataria BTS which then with calm will try to realize one logon to the fixed net so as to to avoid that forms one long chain.