With fast and prosperous development in communication technology, desktop or mobile devices may be equipped with wired and wireless network interfaces. Hence, users need a multihoming technique to help them making use of the network in- terfaces effectively. The Stream Control Transmission Protocol (SCTP) is a new transport protocol approved by the SIGTRAN Working Group of IETF (Internet Engineering Task Force) as RFC 2960 in October 2000 where it includes this useful characteristic. However, this feature may lead to some secure pitfalls. In this thesis, we come up with some approaches to improve SCTP against some existing tough problems raised from multihoming and provide more sufficient protection methods based on cryptography. Finally, a comparison of the existing security solutions is also given to demonstrate our contributions.

With the advent of telecommunication technology, the need to transport multimedia content is increasing day by day. Successful video transmission over the wireless network faces a lot of challenges because of the limited resource and error prone nature of the wireless environment. To deal with these two challenges, not only the video needs to be compressed very efficiently but also the compression scheme needs to provide some error resilient features to deal with the high packet loss probability. In this thesis, we have worked with the H.264/ Advanced Video Coding (AVC) video compression standard since this is the most recent and most efficient video compression scheme. Also H.264 provides novel error resilient features e.g. slicing of the frame, Flexible Macroblock Ordering (FMO), data partitioning etc. In this thesis, we investigate how to utilize the error resilient schemes of H.264 to ensure a good quality picture at the receiving end. In the first part of the thesis, we find the optimum slice size that will enhance the quality of video transmission in a 3G environment. In the second part, we jointly optimize the data partitioning property and partial reliability extension property of the new transport layer protocol, Stream Control Transmission Protocol (SCTP). In the third and last part, we focus more on the network layer issues. We obtain the optimum point of application layer Forward Error Correction (FEC) and Medium Access Control (MAC) layer retransmission in a capacity constrained network. We assume that the bit rate assigned for the video application is more than the video bit rate so that the extra capacity available can be used for error correction.

The research reported in this thesis investigates the performance of the transport layer Stream Control Transfer Protocol (SCTP) for streaming video over CDMA2000 cellphone and data wireless networks. The main measure of performance was quality of the received video at a given buffer size, as cellphones have memory of limited capacity. The hypothesis was that SCTP would be able to improve the quality of streamed video over UDP under the same memory requirements. Our study involved two series of simulation experiments and measurements in a testbed on the Telecom NZ CDMA2000 network, to test the performance of video streaming under SCTP and under UDP. It was found that SCTP did not improve the quality in streamed video with up to 5 second buffers. While other scenarios that have been tested by other people with high packet loss or congestion have shown that SCTP can improve the quality, the CDMA2000 network does not suffer from the impairments that SCTP could neutralise, and because of that, in this scenario, the quality of video streaming under SCTP and UDP are similar. The complexity that SCTP adds does not correspond to an increase in quality.

With the advent of telecommunication technology, the need to transport multimedia content is increasing day by day. Successful video transmission over the wireless network faces a lot of challenges because of the limited resource and error prone nature of the wireless environment. To deal with these two challenges, not only the video needs to be compressed very efficiently but also the compression scheme needs to provide some error resilient features to deal with the high packet loss probability. In this thesis, we have worked with the H.264/ Advanced Video Coding (AVC) video compression standard since this is the most recent and most efficient video compression scheme. Also H.264 provides novel error resilient features e.g. slicing of the frame, Flexible Macroblock Ordering (FMO), data partitioning etc. In this thesis, we investigate how to utilize the error resilient schemes of H.264 to ensure a good quality picture at the receiving end. In the first part of the thesis, we find the optimum slice size that will enhance the quality of video transmission in a 3G environment. In the second part, we jointly optimize the data partitioning property and partial reliability extension property of the new transport layer protocol, Stream Control Transmission Protocol (SCTP). In the third and last part, we focus more on the network layer issues. We obtain the optimum point of application layer Forward Error Correction (FEC) and Medium Access Control (MAC) layer retransmission in a capacity constrained network. We assume that the bit rate assigned for the video application is more than the video bit rate so that the extra capacity available can be used for error correction.

Licentiatavhandling Karlstad : Karlstads universitet, 2008.

There are several weaknesses in the popular transport protocol TCP (Transmission Control Protocol). A possible replacement to TCP would be the newer protocol SCTP (Steam Control Transmission Protocol). This thesis presents three different proposed implementations of SCTP: HTTP over SCTP, online games over SCTP and IP mobility over SCTP. The proposed implementations are analyzed, based on relevant literature, and recommendations are issued on the importance of moving forward with them. The result of the thesis is that HTTP over SCTP is recommended. SCTP features such as multi-streaming, multi-homing and the four-way handshake addresses the inherent weaknesses with using TCP for HTTP traffic. IP mobility over SCTP is also recommended since it results in lower delay in the handover process compared to MIPv6 (Mobile IPv6). Online games over SCTP, however, is not recommended since the existing implementations of SCTP results in poor latency for the kind of traffic online games produce.

With the advent of telecommunication technology, the need to transport multimedia content is increasing day by day. Successful video transmission over the wireless network faces a lot of challenges because of the limited resource and error prone nature of the wireless environment. To deal with these two challenges, not only the video needs to be compressed very efficiently but also the compression scheme needs to provide some error resilient features to deal with the high packet loss probability. In this thesis, we have worked with the H.264/ Advanced Video Coding (AVC) video compression standard since this is the most recent and most efficient video compression scheme. Also H.264 provides novel error resilient features e.g. slicing of the frame, Flexible Macroblock Ordering (FMO), data partitioning etc. In this thesis, we investigate how to utilize the error resilient schemes of H.264 to ensure a good quality picture at the receiving end. In the first part of the thesis, we find the optimum slice size that will enhance the quality of video transmission in a 3G environment. In the second part, we jointly optimize the data partitioning property and partial reliability extension property of the new transport layer protocol, Stream Control Transmission Protocol (SCTP). In the third and last part, we focus more on the network layer issues. We obtain the optimum point of application layer Forward Error Correction (FEC) and Medium Access Control (MAC) layer retransmission in a capacity constrained network. We assume that the bit rate assigned for the video application is more than the video bit rate so that the extra capacity available can be used for error correction. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The mass popularization of telecommunication services in recent years have resulted in a heavily loaded signaling network. The Signaling System number 7 (SS7) is used in fixed and wireless networks and is needed for call control and services such as caller ID, roaming, and for sending SMS. The traditional SS7 networks are expensive to lease and to expand, hence a new suite of protocols have been designed to carry signaling messages over IP. This suite contains a transport protocol called Stream Control Transmission Protocol (SCTP) and various user adaptation layer protocols such as M2PA, M2UA, M3UA, and SUA. To transport the highly loss and delay sensitive signaling messages over IP, it is mandatory that the transport protocol meets the high performance requirements of SS7. Not before the IP-solution has been tested in detail, will it replace significant parts of the national telephone network. In this thesis, the failover duration in the case of link failure was tested using the feature of SCTP called multi-homing. The results suggest that carrying SS7 signaling traffic over IP is possible, since the failover duration does not exceed the required limit. / Under de senaste åren har telekommunikationstjänster blivit allt mer populära, vilket har lett till ett tungt belastat signaleringsnätverk. The Signaling System number 7 (SS7) används i fasta och trådlösa nätverk och behövs för att kontrollera telefonsamtal och för tjänster såsom caller ID, roaming och för att skicka SMS. De traditionella SS7- nätverken är dyra att hyra och att expandera, varför en ny grupp av protokoll har designats för att bära signaleringsmeddelanden över IP. De nya protokollen innehåller ett transportprotokoll som heter Stream Transmission Control Protocol (SCTP) och flera adaptionslagerprotokoll, bl.a. M2PA, M2UA, M3UA och SUA. För att transportera de förlust- och förseningskänsliga signaleringsmeddelandena över IP, måste transportprotokollet möta de höga krav som SS7 har. Inte förrän IP-lösningen har testats ingående, kommer den att ersätta betydelsefulla delar av det nationella telefonnätet. I detta examensarbete har failovertiden mätts då en nätverkslänk mellan två noder har utsatts för ett avbrott. Resultaten pekar på att det är möjligt att bära SS7-trafik över IP eftersom failovertidskraven inte överstigs.

Today mobile network operators utilize IP Packet exchange (IPX) carriers to interconnect their networks with other operators. Mobile network operators are free to choose one IPX carrier for their data traffic and another for their control traffic. This thesis examines the case of control traffic, specifically Stream Control Transmission Protocol (SCTP) carrying Diameter protocol traffic arising from users roaming from their home Long Term Evolution (LTE) network to another operator’s LTE network. The thesis project aims to identify a set of SCTP parameter configurations that can provide improved application/service level availability between two Diameter nodes in different network connectivity environments, specifically for IPX carriers who are Diameter service providers. These service providers provide Diameter connectivity for their customers who are mobile network operators. These mobile network operators in turn provide LTE roaming services to their customers. Unfortunately, applying the ‘One size fits all’ configuration recommendations given in the SCTP documentation is unsuitable for different network environments. In addition, the amount of Diameter signaling traffic is growing at a very rapid rate. Therefore, it is valuable to identify suitable parameter selection criteria for Diameter service providers to ensure 100% Diameter connectivity reliability for their customers. In this thesis project, author investigated how tuning SCTP parameter values affect Diameter message transmission in terms of Round Trip Delay and identified its determining parameters for packet loss recovery performance. Both IPX carriers and mobile network operators may use these values as reference when attempting to ensure high availability of Diameter transmissions under reliable, semi reliable, and unreliable network transport conditions. / Mobilnätsoperatörer använder sig av IP Packet exchange (IPX) tjänstetillhandahållare för att koppla ihop sina nät med andra operatörers nät. Mobilnätsoperatörer kan fritt välja en IPX tjänstetillhandahållare för sin datatrafik och en annan för sin kontrolltrafik. Denna uppsats undersöker fallet för kontrolltrafik, specifikt Stream Control Transmission Protocol (SCTP) kommunikationsprotokoll för Diameter protocol-trafik vid användares roaming från sitt Long Term Evolution (LTE)-hemmanät till en annan operatörs LTE-nät. Examensarbetet avser etablera en uppsättning av SCTP-parameterkonfigurationer som ger förbättrad applikations-/tjänstetillgänglighetsnivå mellan två Diameter-noder i olika nätmiljöer, särskilt för IPX tjänstetillhandahållare som är Diameter tjänstetillhandahållare.  Dessa tjänstetillhandahållare erbjuder Diameter-konnektivitet till sina kunder, som är mobilnätsoperatörer. Dessa mobilnätsoperatörer tillhandahåller i sin tur LTE-roamingtjänster till sina kunder. Tyvärr är det olämpligt att tillämpa de enhetliga konfigurationsrekommendationer, som ges i SCTP- och Diameter-protokollens dokumentation, i olika nätmiljöer. Samtidigt ökar Diameter-signaleringstrafiken mycket snabbt. Därför är det värdefullt att identifiera lämpliga parameterkriterier för Diameter-tjänstetillhandahållare att säkerställa 100% tillförlitlig Diameter-tillgänglighet för sina kunder. I detta examensarbete har författaren undersökt hur trimning av SCTP-parametervärden påverkar Diameter-meddelandeöverföring vad avser överföringstiden tur- och retur, och identifierat de avgörande parametrarna för återställande av paketförluster. Både IPX tjänstetillhandahållare och mobilnätsoperatörer kan använda dessa värden som referens för att åstadkomma hög tillgänglighet för Diameter-överföring vid tillförlitliga, halvtillförlitliga och otillförlitliga nättransportförutsättningar.

In recent years, Internet and IP technologies have made inroads into almost every commu- nication market ranging from best-effort services such as email and Web, to soft real-time applications such as VoIP, IPTV, and video. However, providing a transport service over IP that meets the timeliness and availability requirements of soft real-time applications has turned out to be a complex task. Although network solutions such as IntServ, DiffServ, MPLS, and VRRP have been suggested, these solutions many times fail to provide a trans- port service for soft real-time applications end to end. Additionally, they have so far only been modestly deployed. In light of this, this thesis considers transport protocols for soft real-time applications. Part I of the thesis focuses on the design and analysis of transport protocols for soft real- time multimedia applications with lax deadlines such as image-intensive Web applications. Many of these applications do not need a completely reliable transport service, and to this end Part I studies so-called partially reliable transport protocols, i.e., transport protocols that enable applications to explicitly trade reliability for improved timeliness. Specifically, Part I investigates the feasibility of designing retransmission-based, partially reliable transport protocols that are congestion aware and fair to competing traffic. Two transport protocols are presented in Part I, PRTP and PRTP-ECN, which are both extensions to TCP for partial reliability. Simulations and theoretical analysis suggest that these transport protocols could give a substantial improvement in throughput and jitter as compared to TCP. Additionally, the simulations indicate that PRTP-ECN is TCP friendly and fair against competing congestion- aware traffic such as TCP flows. Part I also presents a taxonomy for retransmission-based, partially reliable transport protocols. Part II of the thesis considers the Stream Control Transmission Protocol (SCTP), which was developed by the IETF to transfer telephony signaling traffic over IP. The main focus of Part II is on evaluating the SCTP failover mechanism. Through extensive experiments, it is suggested that in order to meet the availability requirements of telephony signaling, SCTP has to be configured much more aggressively than is currently recommended by IETF. Fur- thermore, ways to improve the transport service provided by SCTP, especially with regards to the failover mechanism, are suggested. Part II also studies the effects of Head-of-Line Blocking (HoLB) on SCTP transmission delays. HoLB occurs when packets in one flow block packets in another, independent, flow. The study suggests that the short-term effects of HoLB could be substantial, but that the long-term effects are marginal.