UNIVERSAL MOBILE TELECOMMUNICATION SYSTEM(UMTS)

EVOLUATION OF MOBILE COMMUNICATION 1 st Generation : Analog Cellular 2 nd Generation : Multiple Digital System 2 nd -3 rd Generation: GSM Evaluation IMT-2000

TOWARDS UMTS GSM—A digital, mobile, radio standard developed for mobile, wireless, voice communications. GPRS—An extension of GSM networks. UMTS—An extension of GPRS networks.

INTRODUCTION OF UMTS INTRODUCTION OF UMTS Specified by the Third Generation Partnership Project (3GPP). Goal is the delivery of multimedia services to the user in the mobile domain. In GSM only data rates of 9.6 kbit/s are currently supported. In UMTS, data rates of from 144kbit/s to 2 Mbit/s are supported.

Provide the user with an even higher data rate capability. Key requirement is evolution of the core network architecture used in GSM to allow current GSM operators to upgrade of networks to support UMTS.

Spectrum allocation

WARC allocated 230 MHz of spectrum for the implementation of a single world-wide 3G mobile system from the year allocation split into the frequency bands  1885–2025 MHz.  2110–2200 MHz. subbands 1980–2010 MHz and 2170–2200 MHz are for the satellite component. Remainder for the terrestrial component. ERC of the CEPT is responsible for the allocation of radio frequencies.

155 MHz of spectrum reserved for the terrestrial component of 3G systems. 155 MHz is split into  Paired bands.  Unpaired bands. Paired bands -FDD operation Unpaired bands -TDD operation

UMTS STANDARDS Vital that standards exist to define ‘open’ interfaces between the various system components. ITU sets its timetable in 1995 for process of its 3G standard, IMT ETSI is responsible for the technical development of GSM and UMTS.

ITU timeline for 3G standardizations

SMG committee compared five alternative proposals for the multiple access scheme. Alpha, Beta, Gamma, Delta and Epsilon. FMA1 with spreading provided the basis for the Delta Concept. FMA1 without spreading the basis for the Gamma concept. FMA2 the basis for the Alpha concept.

ETSI UTRA air interface technology proposals

UTRA parameters

UTRA system architecture UMTS Terrestrial Radio Access Network, or UTRAN. A UTRAN consists of one or more radio network subsystems (RNSs). RNS:  Base stations (termed Node Bs).  Radio network controllers (RNCs). Node B serve one or multiple cells.

UTRAN system architecture

The use of multiple radio links across multiple cells in support of a single UTRAN–UE connection. links may exist across different Node Bs in neighboring RNCs. Iur participates in mobility switching.

Simplified protocol diagram

Running between a UE and the UTRAN. Transport channels carry control plane or user plane data between the UE and RNC. MAC and RLC layer reside in the RNC. FP is responsible for the relaying of transport channels between the UE and the RNC via Node B.

Radio resource control signalling protocols

NBAP runs over the Iub interface. RNSAP over the Iur interface. RANAP over the Iu interface. NBAP responsible for allocation and control of radio resources. RNSAP responsible for co-ordination of radio resources between Bs and RNCs.

RANAP is used  To support signaling across the Iu interface.  For the establishment of layer connection between UTRAN and core network.

UMTS SECURITY The 3GPP Mutual authentication in UMTS Cryptographic algorithms for UMTS

1. 3GPP leading ideas for 3G was to ensure fully global roaming. To use the mobile system services all over the world. success of GSM had a two-fold effect on the development of the new generation system.  Positive Effect  Negative Effect

UMTS was done on theoretical basis only. Lots of effort was put on the security side. Options remained open. ETSI from Europe, ARIB and TTC from Japan, ANSI from North America, TTA from South Korea formed the 3GPP. Sixth partner from China.

2. 2. Mutual authentication in UMTS  Home environment and Authentication Center (AuC).  Serving network with Visitor Location Register (VLR).  Terminal, more specially USIM (typically in a smart card).

AuC has a copy of the subscriber's master key K. AuC derives authentication vectors of five components RAND, XRES, CK, IK, and AUTN. In GSM, serving network checks subscriber's identity by a challenge response technique. Terminal checks that the serving network has been authorized By the home environment to do so. In UMTS, in serving network, one authentication vector is needed for each authentication instance.

The result of the computation gives USIM the ability to verify whether the parameter AUTN was indeed generated in AuC, and was not sent before to USIM. Verification is based on the value of SQN. Two counters are maintained synchronized in the AuC and in the USIM. Serving network compares RES with the expected response XRES.

3. 3. Cryptographic algorithms for UMTS Three specification strategies: 1. Select an algorithm. 2. Invite submissions. 3. Commission a special group to design an algorithm. Different implications to suitability, security, and timely delivery of the algorithm.

Feasibility of each strategy is based on different assumptions about availability of resources. Separate strategy must be defined for the security evaluation of the specified algorithm before it is adopted for use.

UMTS SERVICES Internet Access. Intranet/Extranet Access. Customized information. Multimedia Messaging. Location Based Services.

CONCLUSION UMTS summarized as a revolution of the air interface accompanied by an evolution of the core network. Handover and backward compatibility with GSM will ensure that both technologies will coexist for many years. The UMTS Forum predicts that the number of mobile phone users will increase to 1800 million world-wide by 2010.