General Packet Radio Service Support Node Research Articles

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 Credit Re-authorization Cost in UMTS Online Charging System

During an online charging general packet radio service (GPRS) session, a number of mid-session events, such as changes of quality of service (QoS), could dynamically affect the rating of the in-progress service. When such events occur, the GPRS support node needs to re-authorize the granted credit units with the online charging system (OCS). This paper proposes a threshold-based scheme that utilizes a threshold parameter delta to reduce the signaling traffic for the credit re-authorization procedure. By selecting an appropriate delta value, the signaling overhead in the OCS can be significantly reduced while the inaccuracy of the credit information insignificantly increases. The mobile operator can choose appropriate parameter values in the threshold-based scheme based on our study.

Overload control for short message transfer in GPRS/UMTS networks

In the General Packet Radio Service (GPRS)/Universal Mobile Telecommunications System (UMTS) short message service (SMS) network, the serving GPRS support node (SGSN) stores the message in a queue until it is successfully transferred to the mobile device or its maximum waiting time expires. The queued message is forwarded to the new SGSN and is immediately removed from the waiting queue of the old SGSN, if the corresponding mobile device leaves the old SGSN area before the valid queueing time expires. Once the SGSN's buffer is full, all incoming messages must be discarded and retransmitted later. Under this situation, the messages, especially the forwarded messages, suffer from a longer delay before being successfully delivered. To prevent messages from being excessively delayed, this paper proposes an SGSN overload control scheme called the N- overload scheme. According to this scheme, a newly arriving message is discarded if the buffer is full upon its arrival. A forwarded message, however, is queued in an overload space of size N. Taking the forwarding and the expiration effects of queued messages into account, this paper also develops an analytical model to study the performance for the SGSN using the N-overload scheme. On the basis of the analysis, the optimal value of N is numerically determined so that the loss probability for the forwarded messages is minimized.

GPRS security as a QoS in the telecommunication industry case of Vodafone Egypt

The changes taking place in the world today are largely due to the developments and evolution in a number of industries; one of which is information and communication technology. Focusing on communications solutions with an emphasis on business applications, it is obvious to claim that business applications that are being deployed with 2.5G wireless networks fall into two general categories: (a) horizontal applications “mobile office” such as electronic mailing, voice communications, Internet access, short messaging and personal information management (PIM) tools and (b) vertical applications “sales force automation”(SFA) and field force automation (FFA), fleet management, government communications and public safety, telemetry and remote monitoring, point-of-sale as well as financial services. The new generation of wireless devices being introduced to the market for 2.5G global system for mobile communications (GSM) and general packet radio service (GPRS) services is designed to support these applications, with features ranging from small standard keyboards to high resolutions rich colored screens. The impressive growth of cellular mobile telephony as well as the number of Internet users promises an exciting potential for a market that combines both innovations. The general packet radio service (GPRS) is a new non-voice value-added service that allows information to be sent and received across a mobile telephone network. Users of GPRS benefit from shorter access time and higher data rates. It is important to note that the standard GPRS network itself does not offer a reasonably secure solution for providing mobile access to a corporate local area network (LAN). Although, the air interface ciphering and the GPRS authentication process are secured, the IP traffic is unencrypted all the way from the serving GPRS support node (SGSN) to the corporate LAN gateway. The most feasible solution for secure remote connections would be to use an end-to-end virtual private network (VPN) solution from the mobile station (MS) to the corporate LAN gateway where the traffic is encrypted for the whole connection and the user can slip to the Internet from the nearest access point. It is important to separate the user traffic from the control traffic to guarantee high level of security with a minor impact on quality of service (QoS) which means providing consistent and predictable data delivery service that can lead to customer application requirement satisfaction. However, to achieve that security has to be looked at as the key player in the new GSM data networks when deploying GPRS. This paper 1 1 The paper is based on a research conducted by Mohammed M M El Sayed in 2002 as part of fulfilling his Master of Science requirements for a degree in business information technology from Middlesex University in the UK. demonstrates the case of Vodafone Egypt, one of the mobile operators, in deploying GPRS networks while focusing on exploring the business opportunities and motivating factors to implement GPRS. Moreover, the paper proposes solutions on how to create secure connections over GPRS networks while proposing a security policy for Vodafone Egypt.

A mobility management strategy for gprs

In general packet radio service (GPRS), a mobile station (MS) is tracked at the cell level during packet transmission, and is tracked at the routing-area (RA) level when no packet is delivered. A READY timer (RT) mechanism was proposed in 3GPP 23.060 to determine when to switch from cell tracking to RA tracking. In this mechanism, a threshold interval T is defined. If no packet is delivered within T, the MS is tracked at the RA level. When a packet arrives, the MS is tracked at the cell level again. However, the RT mechanism has a major fallacy in that the RTs in both the MS and the serving GPRS support node may lose synchronization. This paper considers another mechanism called READY counter (RC) to resolve this problem. In this approach, a threshold K is used. Like the RT approach, the MS is tracked at the cell level during packet transmission. If no packets are delivered after the MS has made K cell crossings, the MS is tracked at the RA level. We also devise an adaptive algorithm called dynamic RC (DRC). This algorithm dynamically adjusts the K value to reduce the location update and paging costs. We propose analytic and simulation models to investigate RC, RT, and DRC. Our study indicates that RC may outperform RT. We also show that DRC nicely captures the traffic-mobility patterns and always adjusts the K threshold close to the optimal values.

Determining the optimal buffer size for short message transfer in a heterogeneous GPRS/UMTS network

Multimedia messaging service (MMS) enables the transmission of messages with full content versatility between mobile devices and from applications to these devices, which can be used over the general packet radio service (GPRS)/universal mobile telecommunications system (UMTS) short message service (SMS) network. In the GPRS/UMTS SMS network, the serving GPRS support node (SGSN) stores the mobile-terminated message in a queue until it is successfully transferred to the mobile device or its maximum waiting time expires. If the mobile device moves from one SGSN area to another before the waiting time has expired, the queued message is forwarded to the new SGSN and is immediately removed from the waiting queue of the old SGSN. Taking the forwarding and the expiration effects of queued messages into account, the paper develops an analytical model to study the system performance of a heterogeneous GPRS/UMTS SMS network, in which the parameters (e.g., message arrival rate, SGSN area residence time, buffer size, etc.) of SGSNs can be varied. On the basis of the analytical model, an iterative method is proposed to determine the optimal buffer size so that the available bandwidth is fully utilized and the message loss probability is minimized.