UMTS Wireless Communication System (2)

UMTS Wireless Communication System (2)

Wireless Communications

UMTS network architecture:

(RNC)  Radio Network Controller

(MSC)  Mobile Switching Center
(UE)     User Equipment
(SGSN) Serving Gprs Support Node
(PDN)   Packet Data Network
(PSTN) Public Switched Telephony Network

Spectrum allocation:

The 2100 MHz band (downlink around 2100 MHz and uplink around 1900 MHz) allocated for UMTS in Europe and most of Asia is already used in North America. The 1900 MHz range is used for 2G (PCS) services, and 2100 MHz range is used for satellite communications. Regulators have, however, freed up some of the 2100 MHz range for 3G services, together with a different range around 1700 MHz for the uplink.

Interoperability and global roaming:

UMTS phones (and data cards) are highly portable—they have been designed to roam easily onto other UMTS networks (if the providers have roaming agreements in place).

In addition, almost all UMTS phones are UMTS/GSM dual-mode devices, so if a UMTS phone travels outside of UMTS coverage during a call the call may be transparently handed off to available GSM coverage. Roaming charges are usually significantly higher than regular usage charges. Most UMTS licensees consider ubiquitous, transparent global roaming an important issue. To enable a high degree of interoperability, UMTS phones usually support several different frequencies in addition to their GSM fallback. Different countries support different UMTS frequency bands – Europe initially used 2100 MHz while the most carriers in the USA use 850 MHz and 1900 MHz

 T-Mobile has launched a network in the US operating at 1700 MHz (uplink) /2100 MHz (downlink), and these bands are also being adopted elsewhere in the Americas.

 A UMTS phone and network must support a common frequency to work together. Because of the frequencies used, early models of UMTS phones designated for the United States will likely not be operable elsewhere and vice versa. There are now 11 different frequency combinations used around the world—including frequencies formerly used solely for 2G services.

UMTS phones can use a Universal Subscriber Identity Module, USIM (based on GSM's SIM) and also work (including UMTS services) with GSM SIM cards. This is a global standard of identification, and enables a network to identify and authenticate the (U) SIM in the phone. Roaming agreements between networks allow for calls to a customer to be redirected to them while roaming and determine the services (and prices) available to the user.

Converting from GSM/GPRS to UMTS:

From a GSM/GPRS network, the following network elements can be reused:

ü Home Location Register (HLR)

ü Visitor Location Register (VLR)

ü Equipment Identity Register (EIR)

ü Mobile Switching Center (MSC) (vendor dependent)

ü Authentication Center (AUC)

ü Serving GPRS Support Node (SGSN) (vendor dependent)

ü Gateway GPRS Support Node (GGSN)

From a GSM/GPRS communication radio network, the following elements cannot be reused:

ü Base station controller (BSC)

ü Base transceiver station (BTS)

They can remain in the network and be used in dual network operation where 2G and 3G networks co-exist while network migration and new 3G terminals become available for use in the network.

The UMTS network introduces new network elements that function as specified by 3GPP:

ü Node B (base transceiver station)

ü Radio Network Controller (RNC)

ü Media Gateway (MGW)

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