Data Transfer Schemes for 3G Mobile Telecommunication Systems J.G.Markoulidakis,G.L.Lyberopoulos, D.F.Tsirkas, C.N.Konstantinopoulou,K.A.Koutsopoulos National Technical University of Athens (NTUA) Department of Electrical and Computer Eng. 9, Heroon Polytechniou Str. 157 73, Zografou, Athens, GREECE e-mail: ckonsta@,telecom.ntua.gr Keywords: 3G, Data Transfer Schemes, Permanent Node Scheme, Local Node Scheme, the Domain Scheme, Transaction Load, Signaling Load, Procedure Execution Delay, Simulation Model Abstract In mobile communications, distributed database systems fulfill the requirements of storing, accessing and updating user-related data (serviceprojle, location and charging data, security related parameters, etc.). Second generation systems adopt the Home Location Register @Eh’) 1 Visitor Location Register (VLR) concept, while for Third Generation (3C) systems, a number of advanced schemes has been proposed. A common issue inherent in all schemes is the transfer of user data from one database node to another whenever the user changes node area. In this paper, we propose a general data transfer scheme, which allows the grouping of database nodes into “domains”. The advantage of this scheme is that user data is transfirred to a new node, only in case that the user changes domain. The applicability of the proposed scheme for both second and third generation system is investigated from the functional and performance viewpoints. The performance analysis is based on a simulation model and focuses on the transaction load, the signaling load and the procedure execution delay, The results indicate that the database performance improves as the domain size increases. The limiting factor, is the resulting procedure execution delay, due to the increased distance between the actual user location and the node where the user data is stored. Possible enhancements, which aim at firther pe$ormance improvements (e.g., taking into account the user mobility characteristics) are also discussed. 1 Introduction It is anticipated that 3G mobile telecommunication systems will be brought into service by 2001-2. Aiming at the ‘mass market’, 3G will offer a plethora of services (voice, low and high bitrate data, video, etc.) via a range of Mobile Terminals o, operating in both public and private environments (e.g., office and residential areas, transportation media, etc.). This necessitates the existence of a DataBase (DB) system, where huge amount of information (user, terminal, subscription, security and charging related data) should be stored, manipulated and accessed from different locations. As far as the DB implementation is concemed, a centralized solution seems to be completely inefficient (if not feasible). This is because, although all DB queries can be satisfied by a single transaction, a huge amount of real-time transactions has to be satisfied by the centralized node. In addition, the distance between the involved MU and the DB node may introduce extra delays in the procedure execution time. On the contrary, a DistributedDataBase (DDB) system exhibits: o P reduced transaction load per DB node and reduced access delay, by storing Mobile User (MU) data close to the actual MU location. The penalty paid, is the cost due to the additional number of DB nodes, the required intra-DDB communication signaling load, as well as the increased number of transactions per procedure. In this context, DDB solutions should be properly specified to optimize network performance at a minimum cost. Second generation systems adopt the HLRNLR concept [2-41, while for 3G systems, a number of advanced schemes has been proposed. A common issue inherent in all schemes is the transfer of user data from one DB node to another whenever the user changes node area. In this paper, we propose a generic data transfer scheme, which allows the grouping of database nodes into “domains”. The advantage of this scheme is that user data is transferred to a new node, only whenever the user changes a domain. The applicability of the proposed scheme for both second and third generation 0-7803-6684-0/00/$10.00 0 2000 IEEE 34