<p>Gateways handle many functions in todays telecommunication networks and as the move towards IP-based telecommunication networks continue, their importance is growing. Many vendors offer a tiered architecture where logic is separated from the gateways for easy extensibility. Currently gateway control and gateway communication is handled using the H.248 protocol. As more and more equipment starts moving over to SIP based communication there has been a degree of interest in homogenizing the system and possibly replacing the H.248 protocol with a SIP based protocol.</p><p>In this paper we examine how the communication between a gateway controller and gateway may look if implemented in SIP. We also examine the performance characteristics of the proposed protocol from both an execution time, communication size and memory consumption perspective. Implementation and tests will be performed using a language, developed by Ericsson specifically for the telecommunication sector, called Erlang. The protocol designed herein is not intended for production use and is only examined for viability. It is NOT the official stance of Ericsson that H.248 will be replaced with the protocol or any like it.</p>

<p>Nowadays a lot of research efforts focus on Mobile Ad-hoc NETworks (MANETs). A MANET is a collection of mobile autonomous nodes, which can move arbitrary, leading to a constantly changing network topology. However, today most of the information is still stored on wired servers. A wired network has a hierarchical topology, while in a MANET the topology is usually flat to allow for nodes to easily change there position in the network. Due to the different topological natures of these systems, interconnectivity is not trivial.</p><p>To further complicate the situation the Transmission Control Protocol (TCP) is designed for wired networks, in a MANET with different link and route characteristics, as multihop and frequent packet losses, the performance of current TCP proposals drop considerably.</p><p>The purpose of this report is to give an overview of the current MANET – Internet connectivity situation and to evaluate TCP performance in a hybrid MANET where mobile nodes connect to a wired network through a gateway.</p><p>The report is divided into two parts. The first theoretical part will evaluate the different routing and mobility problems that occur in a realistic scenario with multiple gateways. Main problems that will be discussed are: path selection, gateway discovery, handover between gateways and address configuration in current solutions.</p><p>In the last part, a simulation-based evaluation will be made on a simplified scenario where one gateway is linking the two different networks. The simulation will be conducted with ns-2.28, which is extended with support for Uppsala University version of Ad-hoc On-demand Distance Vector (AODVUU) as routing and gateway discovery protocol and TCP AP (Adaptive Pacing) as transport protocol. In the performance evaluation, AODVUU and Destination-Sequenced Distance-Vector Routing (DSDV) combined with TCP Newreno, TCP Vegas and TCP AP will be used. The simulation based evaluation concluded that the best performance was achieved with TCP Vegas in conjunction with AODVUU.</p>

No description available.

UDP (User Datagram Protocol) and RTP (Real-time Transport Protocol), using fixed bit rate to convey data every time period, are the most pervasive transport protocols for multimedia traffic in communications networks. However, unexpected packet delay/jitter may occur when network becomes congested or channel interference remains unresolved. To reduce packet delay and packet loss for real-time traffic in a hybrid network from wired to wireless ad-hoc, this thesis presents RTP rate control with an ad-hoc gateway to dynamically adjust the transmission rate according to network conditions. With the proposed scheme, a source node can distinguish the two network conditions, congestion and interference, by monitoring RTCP (RTP control protocol) packets regularly reported from destination nodes and the associated ad-hoc gateway. Based on the RTCP reports, a sender node can dynamically change its encoding bit rate to improve the quality of real-time traffic. For the purpose of demonstration, we implement the proposed adaptive rate control scheme on a Linux platform for SIP-phone communications. The experimental results have shown that our proposed scheme not only relieves traffic congestion but also increases the number of received data even in the case of severe channel interference.

With the rapid growth of communication, applications in traffic sensor network such as the multimedia service Server Push, are indispensable to business advertising. The applications of server push, for example, the service Push Mail provided by ISP (Internet Service Provider), became much more hot and popular. This paper aims to design a mobile vehicular network to let the people who received the advertisement communicate with the providers of the service. Nevertheless, the handoff problem that arises when traveling brings down the quality of communication. Therefore, seamless handoff becomes a very important issue for us to research. This thesis uses the new SCTP (Stream Control Transmission Protocol) to solve the problem. SCTP not only keeps the advantages of TCP/IP but also provides new support. Allowing the user to own several IP addresses at the same time is one of its important characteristics, which allows you to switch to any other available IP immediately if the transmission is interruptted. With this characteristic, the user barely notices any interruption in the process of handoff. Finally, we propose a new design for SCTP to achieve a response time, and can be used in applications that require a fast response time.

In this thesis, we propose a personal gateway for wireless body area network(WBAN). By using wireless communication and a proper WBAN topology, patients¡¦ physiological signal could be recorded without restricting their mobility. Moreover, integration of several kinds of signals from different sensor nodes in one data platform, personal gateway (PG), can reduce the redundant hardware of individual links as well as the complexity of WBAN. A device for long-term bladder urine pressure measurement is designed as a sensor node of PG. Not only is the design cost reduced, but also the reliability is enhanced by using a 1-atm canceling sensing IA (instrumentation amplifier). Because the urine pressure inside the bladder does not vary drastically, both the sleeping and working modes are required to save the battery power for the long-term observation. To integrate circuits with different supply voltages in PG, a 0.9/1.2/1.8/2.5/3.3/5.0 V wide-range I/O buffer carried out using a typical CMOS process is designed. An input buffer with a logic calibration circuit is used for receiving a low voltage signal. A novel floating N-well circuit is employed to remove the body effect at the output PMOS. Moreover, a dynamic driving detector is included to equalize the turn-on voltages for the output PMOS and NMOS transistors. ZigBee is used as a communication channel in this thesis because of its features, including low power, low complexity, medium range, and medium data rate. The 868/915 MHz mode has lower cost and power consumption than those of 2.4 GHz mode, and the data rate is far enough for WBAN applications. Moreover, lower carrier frequency causes less unnecessary power absorbed by human tissue. Therefore, the ZigBee tranceiver with 868/915 MHz mode is explored. A low power all digital phase lock loop (ADPLL) using a controller which employs a binary frequency searching method is also proposed as a clock generator of PG. Glitch hazards and timing violations which occurred very often in prior ADPLLs are avoided by a novel control method and a new digital-controlled oscillator (DCO) with multiplexers. Besides, the feedback DCO is disabled half a cycle in every two cycles so as to reduce 25% of dynamic power theoretically.

<p>Internet är det mest populära och kraftfulla nätverksbaserade informationssystem, som erbjuder stora mängder data liggande på servrar runt om på olika platser i världen. Det ständiga uppväxandet av Internet, som framför allt var märkvärdig under de senaste åren, har lett till en informationsrevolution som förmodligen kommer att fortsätta ett antal år framåt i tiden. Databaser som sedan flera år tillbaka varit en grund för lagrings- och sökningsfält är tydligen inte mindre efterfrågat, för dess användning på så väl små som stora företag. Sammanslagning av dessa två världar (Internet och databaser) kommer att ge nya möjligheter för skapandet av avancerade informationshanteringsapplikationer. Sammankopplingen av databaser på Internet utförs med hjälp av olika tillvägagångssätt som kallas för gateway, och två av dessa är CGI och ASP som studeras i denna rapport med avseende på deras säkerhet och effektivitet. Under genomförandet av arbetet behandlas varje teknologi enskilt. Teknologierna jämförs sedan och detta leder fram till det slutgiltiga resultatet som visar att ASP är bättre lämpat än CGI vad gäller säkerhet och effektivitet.</p>

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / Network switches are a critical component in any networked FTI data acquisition system in order to allow the forwarding of data from the DAU to the target destination devices such as the network recorder, PCM gateways, or ground station. Larger configurations require one or more switch boxes to handle aggregation, routing, filtering and synchronization via the IEEE 1588 Precision Time Protocol. However, for smaller configurations where space and weight restrictions are more stringent, a separate switch box may not be practical This paper discusses how all the essential features of an FTI network, such as flexible forwarding and filtering and IEEE 1588 synchronization, can be maintained without the need for the separate switch box thus making significant savings on weight and size and reducing cost.

Στην εργασία αυτή, μελετήθηκε η δομή του σύγχρονου ίντερνετ από την σκοπιά του δικτύου και κατέστη σαφές το πως διασυνδέονται οι πάροχοι υπηρεσιών και οι τερματική χρήστες, πως γίνεται η δρομολόγηση και ποιοί αλγόριθμοι χρησιμοποιούνται για τιν επίτευξη της. / This diploma thesis focus on how modern networks connect together in order to create the internet and which algorithms used for the routing of informations that traverse through them.

Intelligent Transport System (ITS) has become a hot research topic over the past decades. ITS is a system that applies the following technologies to the whole transportation management system efficiently, including information technique, wireless communication, sensor networks, control technique, and computer engineering. ITS provides an accurate, real time and synthetically efficient transportation management system. Obviously, Vehicular Ad Hoc NETworks (VANETs) attract growing attention from both the research community and industry all over the world. This is because a large amount of applications are enabled by VANETs, such as safety related applications, traffic management, commercial applications and general applications. When connecting to the internet or communicating with different networks in order to access a variety of services using VANETs, drivers and passengers in different cars need to be able to exchange messages with gateways from their vehicles. A secure gateway discovery process is therefore critical, because vehicles should not be subject to security attacks while they are communicating; however, currently there is no existing protocol focusing on secure gateway discovery. In this thesis, we first analyze and compare current existing secure service discovery protocols and then we propose a Secure Gateway Localization and Communication System for Vehicular Ad Hoc Networks (SEGAL), which concentrates on the security issue in gateway discovery. We focus on the authentication aspect by proposing secure cluster based VANETs, that can ensure the gateway discovery messages exchanged through secure clusters. We present the principle and specific process of our SEGAL protocol and analyze its performance to guarantee its outstanding practical applicability.