Mobile Ad hoc Networks (MANETs) are wireless networks, which consist of a collection of mobile nodes with no fixed infrastructure, where each node acts as a router that participates in forwarding data packets. They are a new paradigm of wireless communications for mobile hosts that are resource-constrained with only limited energy, computing power and memory. Previous studies on MANETs concentrated more on energy conservation in an idealistic environment without taking into consideration, the effects of realistic mobility, interference and fading. The definition of realistic mobility models is one of the most critical and, at the same time, difficult aspects of the simulations of networks designed for real mobile ad hoc environments. The reason for this is that most scenarios for which ad hoc networks are used have features such as dynamicity and extreme uncertainties. Thus use of real life measurements is currently almost impossible and most certainly expensive. Hence the commonly used alternative is to simulate the movement patterns and hence the reproduction of movement traces quite similar to human mobility behavior is extremely important. The synthetic models used for movement pattern generation should reflect the movement of the real mobile devices, which are usually carried by humans, so the movement of such devices is necessarily based on human decisions. Regularity is an important characteristic of human movement patterns. All simulated movement models are suspect because there is no means of accessing to what extent they map reality. However it is not difficult to see that random mobility models such as Random Walk, Random Waypoint (default model used in almost all network simulations), etc., generate movements that are most non-humanlike. Hence we need to focus on more realistic mobility models such as Gauss Markov, Manhattan Grid, Reference Point Group Mobility Model (RPGM), Column, Pursue and other Hybrid mobility models. These models capture certain mobility characteristics that emulate the realistic MANETs movement, such as temporal dependency, spatial dependency and geographic restriction. Also a Rayleigh/Ricean fading channel is introduced to obtain a realistic fading environment. The energy consumed by the data, MAC, ARP and RTR packets using IEEE 802.11 MAC protocol with the various mobility models in fading and non-fading channel conditions are obtained using ns-2 simulations and AWK programs. The realistic movement patterns are generated using three different mobility generators BonnMotion Mobility Generator, Toilers Code and Scengen Mobility Generator. This thesis work performs an in-depth study on th eeffects of realistic mobility and fading on energy consumption, packet delivery ratio and control overhead of MANETs.

Ad hoc networks have emerged recently as an important trend of future wireless systems. The evolving wireless networks are seriously challenging the traditional OSI layered design. In order to provide high capacity wireless access and support new multimedia network, the various OSI layers and network functions should be considered together while designing the network. In this thesis, we briefly discuss performance optimization challenges of ad hoc networks and cross-layer design. Ad hoc wireless networks were implemented by using Network Simulator NS-2 and the wireless physical, data link, dynamic source routing (DSR) routing protocol models have been included in the simulation. Simulations show that the performance begins to drop at the moderate offered load due to congestion. In addition, the mobility and fading cause the route failures and packet loss in wireless environment. To improve the performance for wireless networks, we implemented a congestion-aware cross-layer design in NS-2. The MAC layer adaptively selects a transmission data rate based on the channel signal strength information from physical layer and congestion information from network layer. The MAC layer utilization gathered at MAC layer is sent to DSR as a congestion aware routing metric for optimal route discovery. We modified the source codes of 802.11 MAC layer and DSR protocol. The simulations show that rate adaptation in MAC layer improves the network performance in terms of throughput, delivery ratio, and end-to-end delay; using congestion information from MAC layer in routing discovery improves the performance of the network benefited from overall network load balance.

BSD Socket API for Simulator is a project to run untouched Real World Application (RWA) binaries on the powerful modern general-purpose network simulators. BSD Socket API for Simulator is designed to eliminate most of the drawbacks of previous works. It is simulator independence, so it can make use of the powerful functionality and versatile tools provided by modern general-purpose simulators such as NS-2. It is fully compatible with BSD Socket API, so RWA can be run on it without re-linking and re-compiling. It is transparent to the RWA, so RWAs are run on BSD Socket API for Simulator as they are on normal operating systems. BSD Socket API for Simulator is built on the concept of message redirecting. It has two critical parts: shared library and customized simulator application. The shared library is loaded into the address space of RWA. On one hand, messages sent by RWA are captured by the shared library and redirected to the customized simulator application. On the other hand, messages from simulator are redirected by the customized simulator application to the shared library. BSD Socket API for Simulator has been intensively tested. The test results show that it functions as expected and it has an acceptable performance.

<p>Enhanced packet-data access is a trend in third generation mobile communication system. WCDMA Release 5 introduces HSDPA (High Speed Packet Data Access) with a brand new downlink transport channel HS-DSCH (High Speed Downlink Shared Channel) into 3GPP specification to provide greater capacity. HS-DSCH supports some new feature such as fast link adaptation, fast scheduling and fast HARQ (hybrid ARQ) so as to increase system performance. It efficiently improves power utilization, shortens retransmission time and increases system throughput. </p><p>The focus for this thesis is implementation and simulation of HSDPA functionality with ns-2. There is some previous work has been done, such as EURANE. EURANE is an end to end extension which adds several HSDPA modules to ns-2. This paper addresses the analysis of HSDPA by simulating on HS-DSCH based on EURANE, and extends the power consumption on HS-DSCH.</p>

Enhanced packet-data access is a trend in third generation mobile communication system. WCDMA Release 5 introduces HSDPA (High Speed Packet Data Access) with a brand new downlink transport channel HS-DSCH (High Speed Downlink Shared Channel) into 3GPP specification to provide greater capacity. HS-DSCH supports some new feature such as fast link adaptation, fast scheduling and fast HARQ (hybrid ARQ) so as to increase system performance. It efficiently improves power utilization, shortens retransmission time and increases system throughput. The focus for this thesis is implementation and simulation of HSDPA functionality with ns-2. There is some previous work has been done, such as EURANE. EURANE is an end to end extension which adds several HSDPA modules to ns-2. This paper addresses the analysis of HSDPA by simulating on HS-DSCH based on EURANE, and extends the power consumption on HS-DSCH.

This thesis presents a general simulation framework used for evaluating the performance of bilateral teleoperation systems under consistent and controllable network conditions. A teleoperation system is where an operator uses a master device to control a slave robot through a communication link. The communication link between the master and slave has an important impact on the system performance. Network emulation using ns-2 has been proposed as a way of simulating the communication link. It allows for the network conditions to be controlled and for repeatable results. The proposed setup was used to test the performance of a hydraulic actuator under various conditions of wired and wireless networks. Three control schemes were evaluated using various combinations of time delay and packet loss. The system was also tested simulating wireless communication between the master and slave to determine the effects of transmission power and distance on the performance of the system.

This thesis presents a general simulation framework used for evaluating the performance of bilateral teleoperation systems under consistent and controllable network conditions. A teleoperation system is where an operator uses a master device to control a slave robot through a communication link. The communication link between the master and slave has an important impact on the system performance. Network emulation using ns-2 has been proposed as a way of simulating the communication link. It allows for the network conditions to be controlled and for repeatable results. The proposed setup was used to test the performance of a hydraulic actuator under various conditions of wired and wireless networks. Three control schemes were evaluated using various combinations of time delay and packet loss. The system was also tested simulating wireless communication between the master and slave to determine the effects of transmission power and distance on the performance of the system.

This thesis focuses on the enhancement of the IEEE 802.15.4 beaconless-enabled MAC protocol as a solution to overcome the network bottleneck, less flexible nodes, and more energy waste at the centralised wireless sensor networks (WSN). These problems are triggered by mechanism of choosing a centralised WSN coordinator to start communication and manage the resources. Unlike IEEE 802.11 standard, the IEEE 802.15.4 MAC protocol does not include method to overcome hidden nodes problem. Moreover, understanding the behaviour and performance of a large-scale WSN is a very challenging task. A comparative study is conducted to investigate the performance of the proposed ad hoc WSN both over the low data rate IEEE 802.15.4 and the high data rate IEEE 802.11 standards. Simulation results show that, in small-scale networks, ad hoc WSN over 802.15.4 outperforms the WSN where it improves 4-key performance indicators such as throughput, PDR, packet loss, and energy consumption by up to 22.4%, 17.1%, 34.1%, and 43.2%, respectively. Nevertheless, WSN achieves less end-to-end delay; in this study, it introduces by up to 2.0 ms less delay than that of ad hoc WSN. Furthermore, the ad hoc wireless sensor networks work well both over IEEE 802.15.4 and IEEE 802.11 protocols in small-scale networks with low traffic loads. The performance of IEEE 802.15.4 declines for the higher payload size since this standard is dedicated to low rate wireless personal access networks. A deep performance investigation of the IEEE 802.15.4 beaconless-enabled wireless sensor network (BeWSN) in hidden nodes environment has been conducted and followed by an investigation of network overhead on ad hoc networks over IEEE 802.11 protocol. The result of investigation evinces that the performance of beaconless-enabled ad hoc wireless sensor networks deteriorates as indicated by the degradation of throughput and packet reception by up to 72.66 kbps and 35.2%, respectively. In relation to end-to-end delay, however, there is no significant performance deviation caused by hidden nodes appearance. On the other hand, preventing hidden node effect by implementing RTS/CTS mechanism introduces significant overhead on the network that applies low packet size. Therefore, this handshaking method is not suitable for low rate communications protocol such as IEEE 802.15.4 standard. An evaluation study of a 101-node large-scale beaconless-enabled wireless sensor networks over IEEE 802.15.4 protocol has been carried out after the nodes deployment model was arranged. From the experiment, when the number of connection densely increases, then the probability of packet delivery decreases by up to 40.5% for the low payload size and not less than of 44.5% for the upper payload size. Meanwhile, for all sizes of payload applied to the large-scale ad hoc wireless sensor network, it points out an increasing throughput whilst the network handles more connections among sensor nodes. In term of dropped packet, it confirms that a fewer data drops at smaller number of connecting nodes on the network where the protocol outperforms not less than of 34% for low payload size of 30 Bytes. The similar trend obviously happens on packet loss. In addition, the simulation results show that the smaller payload size performs better than the bigger one in term of network latency, where the payload size of 30 Bytes contributes by up to 41.7% less delay compared with the contribution of the payload size of 90 Bytes.

With the advent of new multimedia applications the demand for in time delivery of data is increased as compared to the reliability. Usually the Transport Layer Protocols, User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) are used to transfer the data over the IP based network like Internet. TCP provides a reliable mechanism to transfer the data but its reliable mechanism results in increase in delay. UDP lacks in providing any acknowledgment mechanism and it does not provide any congestion control mechanism also. However the unreliable behavior of UDP results in less delay in data transfer. Now a days one of the important issues is the Quality of Service (QoS) assurance as the behavior of transport layer protocols can affect the QoS. So in order to avoid these issues some new transport layer protocols have been developed by Internet Engineering Task Force (IETF). Two important transport layer protocols, Datagram Congestion Control Protocol (DCCP) and Stream Control Transmission Protocol (SCTP) are used in this study. DCCP is specially designed to avoid congestion in the network. DCCP is suitable for in time delivery of data and also for its congestion control mechanism. DCCP is an unreliable transport layer protocol, as the real time applications demands for in time delivery rather than reliability. SCTP is another transport layer protocol that provides reliable data transfer. In this research work performance of SCTP, DCCP and UDP has been evaluated using MPEG-4 video over Mobile WiMAX/IEEE 802.16e. The performance of these three transport layer protocols is analyzed in terms of performance metrics like packet loss, jitter, delay and throughput. By analyzing these performance measures it is found that the performance of DCCP and SCTP is much better as compared to UDP but DCCP gives much better performance then SCTP when compared in terms of throughput and packet loss. Comparing SCTP and DCCP with UDP in terms of delay and jitter shows that UDP has less delay and jitter as compared to SCTP and DCCP, but because of less throughput and large number of packet loss, UDP can badly degrade the video quality. So, it is found that the DCCP is the most suitable transport layer protocol for transportation of MPEG-4 traffic over Mobile WiMAX/IEEE 802.16e.

Mobile Ad Hoc Networks are flexible, self configuring networks that do not need a fixed infrastructure. When these nets are simulated, mobility models can be used to specify node movements. The work in this thesis focuses on designing an extension of the random trip mobility model on a city section from EPFL (Swiss federal institute of technology). Road data is extracted from the census TIGER database, displayed in Google Earth and used as input for the model. This model produces output that can be used in the open source network simulator ns-2. We created utilities that take output from a database of US counties, the TIGER database, and convert it to KML. KML is an XML based format used by Google Earth to store geographical data, so that it can be viewed in Google Earth. This data will then be used as input to the modified mobility model and finally run through the ns-2 simulator. We present some NAM traces, a network animator that will show node movements over time. We managed to complete most of the goals we set out, apart from being able to modify node positions in Google Earth. This was skipped because the model we modified had an initialization phase that made node positions random regardless of initial position. We were also asked to add the ability to set stationary nodes in Google Earth; this was not added due to time constraints.