<p>Abstract</p><p>This master thesis investigates several di®erent channel estimation techniques in an SC-</p><p>FDMA (Single Carrier Frequency Division Multiple Access) system with parameters set</p><p>according to the standards of 3GPP LTE (3rd Generation Partnership Project Long Term</p><p>Evolution). 3GPP LTE is the name given to a project within the 3GPP to improve the</p><p>mobile phone standard to cope with future requirements. In this thesis, we ¯rst introduce</p><p>the SC-FDMA system, which is a transmission technique that utilizes single carrier mod-</p><p>ulation, then ¯ve types of estimators are investigated. Essential to all channel estimatiors</p><p>is the use of pilot symbols. In the last part we compare the performance of the channel</p><p>estimation techniques with each other in di®erent environments by analysing their symbol</p><p>error rates. All simulations are done in a Matlab environment.</p>

The problem of ensuring Quality of Service (QoS) on a TCP/IP based fixed-infrastructure network has been well studied and several working proposals exist. An allied problem is that of ensuring QoS on an ad-hoc wireless network, where the requirements are similar, but the operating conditions are different enough to warrant this problem to be dealt with separately and extensively. The QoS reservation and management schemes which work on a fixed infrastructure network perform poorly in ad-hoc wireless networks, mainly because of the difficulty in reserving bandwidth on a contention-based medium, and problems which arise from the possible motion of the hosts and the variability of the quality of the connection. This thesis is a proposal to use the concept of active nodes to set up and maintain QoS. Active nodes are nodes which can execute code on behalf on other remote applications. An algorithm for using active nodes to set up and maintain QoS parameters is proposed, and the use of buffer reservation schemes in reserving bandwidth is explained. The proposal is implemented on the network simulator NS-2, and we study the uses and limitations of this proposal, with specific reference to the performance under different operating conditions. / Graduation date: 2003

The determination of the optimal location of transceivers is a critical design factor when deploying a wireless local area network (WLAN). The performance of the WLAN will improve in a variety of aspects when the transceivers' locations are adequately determined, including the overall cell coverage to the battery life of the client units. Currently, the most common method to determine the appropriate location of transceivers is known as a site survey, which is normally a very time and energy consuming process. The main objective of this research was to improve current methodologies for the optimal or near-optimal placement of APs in a WLAN installation. To achieve this objective, several improvements and additions were made to an existing computational tool to reflect the evolution that WLAN equipment has experienced in recent years. Major additions to the computational tool included the addition of the capability to handle multiple power levels for the transceivers, the implementation of a more adequate and precise representation of the passive interference sources for the path loss calculations, and the definition of a termination criterion to achieve reasonable computational times without compromising the quality of the solution. An experiment was designed to assess how the improvements made to the computational tool provided the desired balance between computational time and the quality of the solutions obtained. The controlled factors were the level of strictness of the termination criterion (i.e., high or low), and the number of runs performed (i.e., 1, 5, 10, 15, and 20 runs). The low level of strictness proved to dramatically reduce (i.e., from 65 to 70%) the running time required to obtain an acceptable solution when compared to that obtained at the high level of strictness. The quality of the solutions found with a single run was considerably lower than that obtained with the any other number of runs. On the other hand, the quality of the solutions seemed to stabilize at and after 10 runs, indicating that there is no added value to the quality of the solution when 15 or 20 runs are performed. In summary, having the computational tool developed in this research execute 5 runs with the low level of strictness would generate high quality solutions in a reasonable running time. / Graduation date: 2004

The widespread use of TCP as a transport layer protocol for mobile ad-hoc networks and wireline networks has motivated the need to make its implementation highly power efficient specially with respect to ad hoc radio networks. Over the past years many researchers have developed energy efficient protocols for mobile ad-hoc networks. This thesis deals with the various modifications and fine-tunings in the TCP code which, when applied, help in conserving battery power at nodes by saving on the software overhead at the mobile nodes. The various modifications proposed have been tested with actual experiments done on two laptops with Lucent WaveLan wireless cards. The results obtained from the experiments indicate that with certain modifications made in the implementation of TCP code, significant savings in power can be achieved along with an increase in the overall efficiency of TCP over wireless links. Finally, a discussion of how other modifications can be researched and tested as the hardware for mobile systems change is proposed. / Graduation date: 2000

Thesis (MSc)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Leonard J. Cimini, Jr., Electrical and Computer Engineering. Includes bibliographical references.

Not available

Thesis (M.E.)--University of Florida, 2001. / Title from title page of source document. Document formatted into pages; contains xi, 76 p.; also contains graphics. Includes vita. Includes bibliographical references.

Originally presented as the author's thesis (Swiss Federal Institute of Technology), Diss. ETH No. 16683. / Summary in Italian and English; text in English. Includes bibliographical references (p. 171-177).

Originally presented as the author's thesis (Swiss Federal Institute of Technology), Diss. ETH No. 16687. / Summary in German and English, text in English. Includes bibliographical references (p. 175-180).