General Packet Radio Service Support Research Articles

Multi Service Proxy: Mobile Web Traffic Entitlement Point in 4G Core Network

Core part of state-of-the-art mobile networks is composed of several standard elements like GGSN (Gateway General Packet Radio Service Support Node), SGSN (Serving GPRS Support Node), F5 or MSP (Multi Service Proxy). Each node handles network traffic from a slightly different perspective, and with various goals. In this article we will focus only on the MSP, its key features and especially on related security issues. MSP handles all HTTP traffic in the mobile network and therefore it is a suitable point for the implementation of different optimization functions, e.g. to reduce the volume of data generated by YouTube or similar HTTP-based service. This article will introduce basic features and functions of MSP as well as ways of remote access and security mechanisms of this key element in state-of-the-art mobile networks.

Global gateway-based UMTS/WLAN integration for improved delay performance

This paper proposes a loose coupling-based integration between universal mobile telecommunication system (UMTS) and wireless local area networks (WLANs) using mobile Internet protocol (MIP)-based vertical handoff between the two networks. In loose coupling, an integrated network must provide home agent (HA) functionality when a UMTS subscriber moves to WLAN. The position of HA effects the performance of an integrated network. If HA is deployed at gateway GPRS (general packet radio service) support node (GGSN), delay for data as well as control packets increases when both receiving and transmitting mobile stations (MSs) reside in WLAN. Because each packet travels to GGSN through Gi interface, and routed back to WLAN through the same interface. HA can also be deployed in WLAN Internet protocol (IP) network. This improves delay for data packets, but handoff delay from WLAN to UMTS increases because an MS cannot send MIP registration request to HA before the establishment of packet data protocol context in UMTS network. We propose an efficient integration by fixing the position of HA in a global gateway router which is deployed in WLAN IP network. The proposed interworking technique reduces packet delay when both sending and receiving MSs are in WLANs. The methods also update location of a user in UMTS as well as WLAN so that he/she is always reachable from each network irrespective of current position. ns-2-Based simulation results show that our new handoff methods reduce handoff delay from UMTS to WLAN by 10% and that from WLAN to UMTS by 18%.

Reducing authentication signaling traffic in third-generation mobile network

In the Universal Mobile Telecommunication System (UMTS), authentication functions are utilized to identify and authenticate a mobile station (MS) and validate the service request type to ensure that the user is authorized to use the particular network services. The authenticating parties are the authentication center (AuC) in the home network and the MS. In the UMTS, the serving general packet radio service support node (SGSN) accesses the AuC to obtain the authentication data, and delegates the AuC to perform mutual authentication with the MS. Since the cost for accessing AuC is expensive, the SGSN may obtain an array of authentication vectors (AVs) at a time so that the number of accesses can be reduced. On the other hand, if the size K of the AV array is large, the AV array transmission from the AuC to the SGSN may be expensive. Thus, it is desirable to select an appropriate K value to minimize the authentication network signaling cost. We propose an analytic model to investigate the impact of K on the network signaling traffic, which is validated by simulation experiments. Then, we propose an automatic K-selection mechanism that dynamically selects the size of the AV array to reduce the network signaling cost. Our study indicates that the automatic K-selection mechanism effectively identifies appropriate size of the authentication vector array.