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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

DATA PROCESSING DESIGN OF WIDEBAND CODE DIVISION MULTIPLE ACCESS (WCDMA)

RAO, THUMATI VENKATA January 2007 (has links)
Wideband Direct-Sequence Code Division Multiple Access (W-CDMA) is the emerging protocol for the next generation (3G) wireless communication systems. W-CDMA has been designed to add features such as multimedia capabilities, high data rates and multi-rate services to the existing wireless communication framework. Several standards for third generation systems have been proposed and developed by different industrial committees in countries such as the U.S, Europe and Japan. All these standards have accepted CDMA in one form or another as the multiple access method for wireless communications requirements. In this work, we study the implementation issues involved for one of the proposed Rate Compatible Punctured Convolution Coding (RCPC) to increase information rate in WCDMA, the detection algorithms for base-stations. It was found that these proposed algorithms for detection have different processing and precision requirements. In the rate compatible punctured convolution from each coded symbol some of the bits are punctured in order to achieve the higher information rate. At the same time decoding becomes quite easy even if some of the bits from the coded symbol are not available. We have written these algorithms for a single user at ideal conditions based on theory but not practically.
2

Benchmarking of mobile network simulator, with real network data

Näslund, Lars January 2007 (has links)
<p>In the radio network simulator used in this thesis the radio network from a specific operator is modeled. The real network model in the simulator uses, a 3-D building database, realistic site data (antenna types, feederloss, ...) and parameter setting from field. In addition traffic statistics are collected from the customer’s network for the modeled area. The traffic payload is used as input to the simulator and creates an inhomogeneous traffic distribution over the area. One of the outputs from the simulator is power per cell.</p><p>The purposes of this thesis are to identify simulation accuracy compared to reality and to evaluate and improve the simulation models and the methods used when making a simulation of a real WCDMA network with the Astrid simulator.</p><p>In cellular systems the transmitted power influences the interference in the network and the interference is in turn affecting the performance. As the transmitted RBS power influences the downlink interference, it is important that the RBS power level is accurate in the simulator. Therefore the simulated RBS power is benchmarked with the real RBS power. The traffic payload from the real network is used as input into the simulator. Based on the traffic payload the simulator generates RBS power as output. The simulated RBS power is then compared with the measured RBS power.</p><p>It has been found that the standard parameter setting in the simulator gives in average about 1 W too much RBS power used in the simulations compared to reality. After investigation it was detected that two reasons for the overestimated power are that the common control channels (CCCH) power setting and the feederloss is not set to the same values as in field. With the new CCCH settings and feederloss the simulator overestimates the RBS power with 0.5 W in average. As the traffic today is relatively low the parameters that only affect the dedicated channels can only be used to make small adjustments of the simulated RBS power.</p>
3

Benchmarking of mobile network simulator, with real network data

Näslund, Lars January 2007 (has links)
In the radio network simulator used in this thesis the radio network from a specific operator is modeled. The real network model in the simulator uses, a 3-D building database, realistic site data (antenna types, feederloss, ...) and parameter setting from field. In addition traffic statistics are collected from the customer’s network for the modeled area. The traffic payload is used as input to the simulator and creates an inhomogeneous traffic distribution over the area. One of the outputs from the simulator is power per cell. The purposes of this thesis are to identify simulation accuracy compared to reality and to evaluate and improve the simulation models and the methods used when making a simulation of a real WCDMA network with the Astrid simulator. In cellular systems the transmitted power influences the interference in the network and the interference is in turn affecting the performance. As the transmitted RBS power influences the downlink interference, it is important that the RBS power level is accurate in the simulator. Therefore the simulated RBS power is benchmarked with the real RBS power. The traffic payload from the real network is used as input into the simulator. Based on the traffic payload the simulator generates RBS power as output. The simulated RBS power is then compared with the measured RBS power. It has been found that the standard parameter setting in the simulator gives in average about 1 W too much RBS power used in the simulations compared to reality. After investigation it was detected that two reasons for the overestimated power are that the common control channels (CCCH) power setting and the feederloss is not set to the same values as in field. With the new CCCH settings and feederloss the simulator overestimates the RBS power with 0.5 W in average. As the traffic today is relatively low the parameters that only affect the dedicated channels can only be used to make small adjustments of the simulated RBS power.
4

Study Comparison of WCDMA and OFDM / Study Comparison of WCDMA and OFDM

Chowdhury, Moyamer, Alam, Aminul January 2007 (has links)
Wideband Code Division Multiple Access (WCDMA) is one of the main technologies for the implementation of third-generation (3G) cellular systems. It is based on radio access technique proposed by ETSI Alpha group and the specifications was finalised 1999. WCDMA is also known as UMTS and has been adopted as a standard by the ITU under the name “IMT-2000 direct spread”. The implementation of WCDMA will be a technical challenge because of its complexity and versatility. The complexity of WCDMA systems can be viewed from different angles: the complexity of each single algorithm, the complexity of the overall system and the computational complexity of a receiver. In WCDMA interface different users can simultaneously transmit at different data rates and data rates can even vary in time. WCDMA increases data transmission rates in GSM systems by using the CDMA air interface instead of TDMA. WCDMA is based on CDMA and is the technology used in UMTS. WCDMA is the dominating 3G technology, providing higher capacity for voice and data and higher data rates. The gradual evolution from today&apos;s systems is driven by demand for capacity, which is required by new and faster data based mobile services. WCDMA enables better use of available spectrum and more cost-efficient network solutions. The operator can gradually evolve from GSM to WCDMA, protecting investments by re-using the GSM core network and 2G/2.5G services. Orthogonal Frequency Division Multiplexing (OFDM) - technique for increasing the amount of information that can be carried over a wireless network uses an FDM modulation technique for transmitting large amounts of digital data over a radio wave. OFDM works by splitting the radio signal into multiple smaller sub-signals that are then transmitted simultaneously at different frequencies to the receiver. OFDM reduces the amount of crosstalk in signal transmissions. 802.11a WLAN, 802.16 and WiMAX technologies use OFDM. It&apos;s also used in the ETSI&apos;s HiperLAN/2 standard. In addition, Japan&apos;s Mobile Multimedia Access Communications (MMAC) WLAN broadband mobile technology uses OFDM. In frequency-division multiplexing, multiple signals, or carriers, are sent simultaneously over different frequencies between two points. However, FDM has an inherent problem: Wireless signals can travel multiple paths from transmitter to receiver (by bouncing off buildings, mountains and even passing airplanes); receivers can have trouble sorting all the resulting data out. Orthogonal FDM deals with this multipath problem by splitting carriers into smaller subcarriers, and then broadcasting those simultaneously. This reduces multipath distortion and reduces RF interference allowing for greater throughput. In this paper we have discussed about these two methods of third generation radio transmission system which are WCDMA and OFDM with various aspects. In between these two radio transmission technique, a better choice will be investigated.
5

A Dynamic Bandwidth Borrowing Algorithm for QoS Support in OVSF-CDMA System

Wu, Peng-Long 26 August 2003 (has links)
Orthogonal variable spreading factor (OVSF) code is used in WCDMA system to provide variable service data rates. However, most researches focus on decreasing the number of code assignment without considering how to manage bandwidth with properties of OVSF code. In this research, we propose a dynamic bandwidth borrowing algorithm for quality of service (QoS) supported in the OVSF-CDMA system. When a new call arrives or a current serviced call requests a higher data rate, but the system can not provide the required bandwidth, the borrowing algorithm can be activated to borrow bandwidth from current serviced calls. Also, a dynamic bandwidth reserved algorithm is proposed to avoid forced termination caused by the suddenly increasing bandwidth requirements of current serviced calls. Simulation results show that the value of throughput increases and the QoS of current serviced calls can be maintained.
6

Code Merge Scheme (CMS) ¡GA Dynamic Scheme for Allocating OVSF Codes in WCDMA

Huang, Tien-Tsun 06 August 2001 (has links)
Abstract Wideband-CDMA (WCDMA) is a kind of third-generation wireless communication system. It can provide multi-rate services and fast transmission with wideband technology. To improve the solution of no enough wireless bandwidth currently, the 3G communication systems have been researched and developed in several leading countries recently. WCDMA adopts a kind of new spreading codes named Orthogonal Variable Spreading Factor codes (OVSF codes) that have advantages of dynamically variable rates and keeping orthogonality. OVSF codes can provide different data transmission rates by assigning codes with different lengths. By building a code tree, we can discuss some better schemes to assign available data rate. In this paper, we propose an efficient channel assignment scheme that can decrease the call blocking rate and complexity of channel reassignment procedure. Based on the properties of the binary code tree, we use code merge scheme to decrease channel reassignment rate and call blocking rate. This will efficiently improve the performance of channel assignment and spectral efficiency. Simulation results show that the proposed scheme has expected results.
7

Timing of fuzzy membership functions from data

Frantti, T. (Tapio) 20 June 2001 (has links)
Abstract In this dissertation the generation and tuning of fuzzy membership function parameters are considered as a part of the fuzzy model development process. The automatic generation and tuning of fuzzy membership function parameters are needed for the fast adaptation and tuning of fuzzy models of various nonlinear dynamical systems. The developed methods are especially useful in automatic fuzzy membership function generation and tuning when dynamic of application area is fast enough to exclude manual tuning. The fuzzy model development process and development methods, modelling environment and nature of application area as well as algorithm development parameters are extensively discussed, because each of them sets their own restrictions on the design parts and parameters used in the modelling. The developed methods have been applied in different kinds of applications (in forecasting the demand of signal transmission products, power control and code tracking of cellular phone system, fuzzy reasoning in radio resource functions of cellular phone systems), where other approaches are either very difficult or too time consuming to implement. The professional areas of the thesis are fuzzy modelling and control in telecommunications.
8

WCDMA in GSM

Suresh Babu, Kongaleti January 2008 (has links)
Multiple Access Techniques is the emerging techniques for the nextgeneration (3G) wireless communication systems. Multiple access techniques hasbeen designed to add features such as multimedia capabilities, high data rates andmulti-rate services to the existing wireless communication framework. The datarates proposed 2, 3 are 2Mbps indoor, 384 Kbps pedestrian, and 144 Kbpsvehicular. Several standards for third generation systems have been proposed anddeveloped by different industrial committees in countries such as the U.S, Europeand Japan. All the standards have accepted in one form or another as the multipleaccess method for wireless communications requirements.In this project, we study the implementation issues involved for one of theproposed multiuser channel estimation and detection algorithms for base-stations.It was found that these proposed algorithms for multiuser channel estimation anddetection have different processing and precision requirements. / Uppsatsnivå: D
9

GSM/WCDMA Leakage Detection System

Johansson, Emil, Myhrman, Kim January 2011 (has links)
Ericsson in Linkoping houses one of the largest test laboratories within thewhole Ericsson Company. Mainly, the laboratories contain equipment forGSM, WCDMA and LTE. To test these systems, a quite large number ofRadio Base Stations are needed. The RBS's are housed in a proportionatelysmall area. Instead of sending signals through the air, cables are used totransfer the RF signals. In this way the equipment communicating witheach other are well speci ed. However this may not be the case if leakageoccur.This thesis work is about developing a system for monitoring the radioenvironment and detect leakages in the test site. There is a need to de newhat a leakage really is and measurements needs to be performed in order toaccomplish this. This report describes how the work has proceeded towardsthe nal implemented solution.
10

Channel estimation for mobile wideband code division multiple access (WCDMA)

Saur, Stephan January 2008 (has links)
Zugl.: Stuttgart, Univ., Diss., 2008

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