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- Title
- Diversity techniques in direct sequence code division multiple access communication systems.
- Creator
- Ugweje, Okechukwu Clark., Florida Atlantic University, Aalo, Valentine A., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
This dissertation investigates the performance of different space diversity combining techniques for the wireless mobile communication systems employing Direct Sequence-Code Division Multiple Access (DS-CDMA). It covers two research topics, all falling under the umbrella of diversity combining techniques. The first part deals with diversity reception of wideband DS-CDMA signals in which the diversity branches experience some correlation. This analysis is performed without the usual assumption...
Show moreThis dissertation investigates the performance of different space diversity combining techniques for the wireless mobile communication systems employing Direct Sequence-Code Division Multiple Access (DS-CDMA). It covers two research topics, all falling under the umbrella of diversity combining techniques. The first part deals with diversity reception of wideband DS-CDMA signals in which the diversity branches experience some correlation. This analysis is performed without the usual assumption that diversity branches are independent and hence uncorrelated. In this case, the analysis is limited to the conventional diversity techniques such as maximal ratio combining, equal gain combining and selection diversity. In particular, the effect of correlation on system performance using two correlation profiles namely, the constant and the exponential correlation profiles is explored. In the constant correlation, the correlation between adjacent antenna are equal regardless of the separation between them, while in exponential correlation, it is assumed that the level of correlation between adjacent antennas decreases as their separation increases. The second topic deals with the development of new combining techniques. Two new techniques--the Generalized Selection Diversity Combining (GSDC) and the Maximal Ratio-Selection Diversity Combining (MR-SDC)--are introduced and analyzed in this dissertation. Analytical models which can be used to evaluate the performance of these new techniques are indicated. Results show that GSDC perform significantly better than the conventional selection diversity when two or more larger signals are selected. The MR-SDC technique accounts for the possibility of using a large array of antennas and for occasions when the receiving antennas may not be collocated. Also, it is shown that for the large array of antennas, better performance is achieved when the MR-SDC is employed with the maximum number of subgroups. The figures of merit used in this dissertation are the average Bit Error Rate (BER) and the probability of outage for a given threshold probability of error. Exact and approximate expressions are derived for the average bit error probability as well as for the outage probability while accounting for the effect of multipath fading, multiple access interference and background noise.
Show less - Date Issued
- 1997
- PURL
- http://purl.flvc.org/fcla/dt/12524
- Subject Headings
- Code division multiple access, Wireless communication systems
- Format
- Document (PDF)
- Title
- Performance analysis of wireless communication systems in multipath fading environments with correlated shadowing and co-channel interference.
- Creator
- Zhang, Jingjun., Florida Atlantic University, Aalo, Valentine A., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
The performance aspects of conventional cellular (FDMA/TDMA) and CDMA systems with micro- and macroscopic diversity reception are investigated in a severe mobile communication environment which is characterized by path loss, correlated lognormal shadowing, multipath fading, background noise and interference. Under a co-channel interference-limited assumption, an exact analytical expression for the co-channel interference (CCI) probability is presented for a macroscopic diversity system with...
Show moreThe performance aspects of conventional cellular (FDMA/TDMA) and CDMA systems with micro- and macroscopic diversity reception are investigated in a severe mobile communication environment which is characterized by path loss, correlated lognormal shadowing, multipath fading, background noise and interference. Under a co-channel interference-limited assumption, an exact analytical expression for the co-channel interference (CCI) probability is presented for a macroscopic diversity system with an arbitrary number of correlated macroscopic branches. For noise-limited systems, the average bit-error-rate (BER) and outage probability performances of a narrowband mobile communication system with micro- and macrodiversity reception are evaluated. In the relevant analysis, both Nakagami and Rician fading channels are considered. When both co-channel interference and noise coexists, the results for a Nakagami fading channel show that diversity reception can be used to reduce the effects of interference while combating fading and shadowing. Micro- and macroscopic diversities are also applied to a multicell DS-CDMA system. In a conventional cellular system with macroscopic diversity, the mobile user is usually connected to the closest base station. However, a base-station selection scheme based on a least attenuation criterion is shown to provide a significant performance improvement over the conventional system. In this case, the system performance is examined in terms of BER and outage probability, while accounting for the effects of path loss, correlated shadowing, multipath fading, multiple access interference, and imperfect power control.
Show less - Date Issued
- 1999
- PURL
- http://purl.flvc.org/fcla/dt/12600
- Subject Headings
- Wireless communication systems, Code division multiple access
- Format
- Document (PDF)
- Title
- Performance analysis of RLP for NAK based ARQ scheme in cdma2000 wireless systems for random error channels.
- Creator
- Easo, Daniel J., Florida Atlantic University, Pandya, Abhijit S.
- Abstract/Description
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This thesis is an effort to present the performance analysis of the RLP in cdma2000, which uses the NAK based ARQ scheme for Random Error Channels. The performance analyses is done in terms of throughput and mean extra delay, which are calculated analytically and are compared with the results generated from the simulations. As the demand for higher data rates increases over the wireless channels, this thesis studies the effect of the random errors over the different types of RLP frame formats...
Show moreThis thesis is an effort to present the performance analysis of the RLP in cdma2000, which uses the NAK based ARQ scheme for Random Error Channels. The performance analyses is done in terms of throughput and mean extra delay, which are calculated analytically and are compared with the results generated from the simulations. As the demand for higher data rates increases over the wireless channels, this thesis studies the effect of the random errors over the different types of RLP frame formats and also the performance of the NAK based ARQ mechanism used in these conditions. The simulation provides with the overall characteristics of the throughput and the mean extra delay in terms of realistic environment parameters like Eb/No and probability of packet error (Pe), based on the channel conditions.
Show less - Date Issued
- 2001
- PURL
- http://purl.flvc.org/fcla/dt/12810
- Subject Headings
- Code division multiple access, Wireless communication systems, Mobile communication systems
- Format
- Document (PDF)
- Title
- Performance evaluation of a DS/CDMA packet transmission system under Rician fading channel conditions.
- Creator
- Argyrides, Christodoulos., Florida Atlantic University, Aalo, Valentine A.
- Abstract/Description
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This thesis is concerned with the performance analysis of a DS/CDMA packet radio system under Rician fading channel conditions. Analytic expressions are derived for the probability density functions and cumulative distribution functions of the total signal-to-interference ratio when considering mixed-type of interference sources. The users are divided into two groups: those that apply closed-loop power control and those that apply open-loop power control. Four different scenarios of power...
Show moreThis thesis is concerned with the performance analysis of a DS/CDMA packet radio system under Rician fading channel conditions. Analytic expressions are derived for the probability density functions and cumulative distribution functions of the total signal-to-interference ratio when considering mixed-type of interference sources. The users are divided into two groups: those that apply closed-loop power control and those that apply open-loop power control. Four different scenarios of power control were studied. The outage probability is evaluated for the four different cases of power control. A packet transmission protocol with forward error correction capabilities is considered, and the probability density functions of the signal-to-interference ratio are used to calculate the average block error probability as well as the outage probability of the system.
Show less - Date Issued
- 2001
- PURL
- http://purl.flvc.org/fcla/dt/12825
- Subject Headings
- Code division multiple access, Packet switching (Data transmission)
- Format
- Document (PDF)
- Title
- Performance of multicarrier DS CDMA systems in a Nakagami fading channel.
- Creator
- Wang, Jifang., Florida Atlantic University, Bagby, Jonathan S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
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The performance of a multicarrier DS CDMA system is evaluated over a Nakagami multipath fading channel. After the spreading process, the data sequence is applied to multiple carrier rather than a single carrier. Each carrier is provided a corralator in the receiver, and the maximal-ratio combiner is used for the corralator outputs. A bandlimited spreading waveforms are used for self-interference prevention. Robustness to multipath fading and narrow band interference suppression are achieved...
Show moreThe performance of a multicarrier DS CDMA system is evaluated over a Nakagami multipath fading channel. After the spreading process, the data sequence is applied to multiple carrier rather than a single carrier. Each carrier is provided a corralator in the receiver, and the maximal-ratio combiner is used for the corralator outputs. A bandlimited spreading waveforms are used for self-interference prevention. Robustness to multipath fading and narrow band interference suppression are achieved by this type of configuration. A comparison is made with a single carrier system in the presence of interference.
Show less - Date Issued
- 1998
- PURL
- http://purl.flvc.org/fcla/dt/15534
- Subject Headings
- Code division multiple access, Wireless communication systems, Radio--Transmitters and transmission--Fading
- Format
- Document (PDF)
- Title
- Visualization as a Qualitative Method for Analysis of Data from Location Tracking Technologies.
- Creator
- Mani, Mohan, VanHilst, Michael, Pandya, Abhijit S., Hsu, Sam, Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
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One of the biggest factors in the quest to better wireless communication is cellular call handoff, which in tum, is a function of geographic location. In this thesis, our fundamental goal was to demonstrate the value addition brought forth by spatial data visualization techniques for the analysis of geo-referenced data from two different location tracking technologies: GPS and cellular systems. Through our efforts, we unearthed some valuable and surprising insights from the data being...
Show moreOne of the biggest factors in the quest to better wireless communication is cellular call handoff, which in tum, is a function of geographic location. In this thesis, our fundamental goal was to demonstrate the value addition brought forth by spatial data visualization techniques for the analysis of geo-referenced data from two different location tracking technologies: GPS and cellular systems. Through our efforts, we unearthed some valuable and surprising insights from the data being analyzed that led to interesting observations about the data itself as opposed to the entity, or entities, that the data is supposed to describe. In doing so, we underscored the value addition brought forth by spatial data visualization techniques even in the incipient stages of analysis of georeferenced data from cellular networks. We also demonstrated the value of visualization techniques as a verification tool to verify the results of analysis done through other methods, such as statistical analysis.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/fau/fd/FA00012536
- Subject Headings
- Mobile communication systems, Algorithms--Data analysis, Radio--Transmitters and transmissions, Code division multiple access
- Format
- Document (PDF)
- Title
- Integrating Multi-user Scheduling with Retransmission Diversity over Wireless Links.
- Creator
- Li, Irena, Zhuang, Hanqi, Wang, Xin, Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
Research presented in this thesis develops a mainly theoretical basis and computer models for enhancing the throughput of multi-user wireless communication networks. The cross-layer combination of an adaptive modulation and coding (AMC) scheme at the physical layer and the use of automatic repeat request (ARQ) retransmi ssions at the data link layer is integrated into a scheduling framework for multi-user networks. Scheduling algorithms incorporating retransmission diversity are derived for...
Show moreResearch presented in this thesis develops a mainly theoretical basis and computer models for enhancing the throughput of multi-user wireless communication networks. The cross-layer combination of an adaptive modulation and coding (AMC) scheme at the physical layer and the use of automatic repeat request (ARQ) retransmi ssions at the data link layer is integrated into a scheduling framework for multi-user networks. Scheduling algorithms incorporating retransmission diversity are derived for three cases of typical network traffic: best-effort, non-realtime, and realtime. For each case, numeric computer si mulations of wireless communications over Nakagami-m block fading channels are developed to examine the effectiveness of the formulated schemes.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/fau/fd/FA00012533
- Subject Headings
- Wireless communication networks, Code division multiple access, Modulation (Electronics), Signal processing (Digital techniques)
- Format
- Document (PDF)
- Title
- A neural network-based receiver for interference cancellation in multi-user environment for DS/CDMA systems.
- Creator
- Shukla, Kunal Hemang., Florida Atlantic University, Pandya, Abhijit S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
The objective of this work is to apply and investigate the performance of a neural network-based receiver for interference cancellation in multiuser direct sequence code division multiple access (DSCDMA) wireless networks. This research investigates a Receiver model which uses Neural Network receiver in combination with a conventional receiver system to provide an efficient mechanism for the Interference Suppression in DS/CDMA systems. The Conventional receiver is used for the time during...
Show moreThe objective of this work is to apply and investigate the performance of a neural network-based receiver for interference cancellation in multiuser direct sequence code division multiple access (DSCDMA) wireless networks. This research investigates a Receiver model which uses Neural Network receiver in combination with a conventional receiver system to provide an efficient mechanism for the Interference Suppression in DS/CDMA systems. The Conventional receiver is used for the time during which the neural network receiver is being trained. Once the NN receiver is trained the conventional receiver system is deactivated. It is demonstrated that this receiver when used along with an efficient Neural network model can outperform MMSE receiver or DFFLE receiver with significant advantages, such as improved bit-error ratio (BER) performance, adaptive operation, single-user detection in DS/CDMA environment and a near far resistant system.
Show less - Date Issued
- 2003
- PURL
- http://purl.flvc.org/fcla/dt/12975
- Subject Headings
- Neural networks (Computer science), Wireless communication systems, Code division multiple access
- Format
- Document (PDF)
- Title
- A quality of service analysis of CDMA-based AODV routing protocol for ad-hoc wireless networks.
- Creator
- Qureshi, Basit Iqbal., Florida Atlantic University, Ilyas, Mohammad, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
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Ad-hoc wireless networks are the networks without an infrastructure. Infrastructure-less mobile networks have no fixed routers or base stations. All nodes in these networks are capable of movement and can be connected dynamically at any time. The issue of routing packets effectively between any nodes in an ad-hoc network is a challenging task. A path that was considered optimal at a given time point may not be working after a few moments. Moreover the bandwidth available between a link may...
Show moreAd-hoc wireless networks are the networks without an infrastructure. Infrastructure-less mobile networks have no fixed routers or base stations. All nodes in these networks are capable of movement and can be connected dynamically at any time. The issue of routing packets effectively between any nodes in an ad-hoc network is a challenging task. A path that was considered optimal at a given time point may not be working after a few moments. Moreover the bandwidth available between a link may not remain the same since every node in this kind of network is behaving as a router and may experience drastical increase in throughput and traffic load. For the purpose of quality of communication, bandwidth reservation within ad-hoc wireless network nodes may prove promising as a solution to this problem. This thesis presents an approach to reserve bandwidth available utilizing CDMA of bandwidth to the Ad-hoc Distance Vector Protocol for the ad-hoc wireless networks. Various quality of service issues are discussed and are tested for optimal performance for AODV routing protocol. A QoS performance comparison based on mobility, congestion and throughput is made between AODV and CDMA based AODV mobile routing protocols.
Show less - Date Issued
- 2002
- PURL
- http://purl.flvc.org/fcla/dt/12895
- Subject Headings
- Code division multiple access, Wireless communication systems, Packet switching (Data transmission)
- Format
- Document (PDF)
- Title
- Low complexity H.264 video encoder design using machine learning techniques.
- Creator
- Carrillo, Paula., Department of Computer and Electrical Engineering and Computer Science, College of Engineering and Computer Science
- Abstract/Description
-
H.264/AVC encoder complexity is mainly due to variable size in Intra and Inter frames. This makes H.264/AVC very difficult to implement, especially for real time applications and mobile devices. The current technological challenge is to conserve the compression capacity and quality that H.264 offers but reduce the encoding time and, therefore, the processing complexity. This thesis applies machine learning technique for video encoding mode decisions and investigates ways to improve the...
Show moreH.264/AVC encoder complexity is mainly due to variable size in Intra and Inter frames. This makes H.264/AVC very difficult to implement, especially for real time applications and mobile devices. The current technological challenge is to conserve the compression capacity and quality that H.264 offers but reduce the encoding time and, therefore, the processing complexity. This thesis applies machine learning technique for video encoding mode decisions and investigates ways to improve the process of generating more general low complexity H.264/AVC video encoders. The proposed H.264 encoding method decreases the complexity in the mode decision inside the Inter frames. Results show, at least, a 150% average reduction of complexity and, at most, 0.6 average increases in PSNR for different kinds of videos and formats.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/FAU/166448
- Subject Headings
- Code division multiple access, Digital media, Technological innovations, Image transmission, Technological innovations, Coding theory, Data structures (Computer science)
- Format
- Document (PDF)
- Title
- Simulation-based performance evaluation of packet-switched H.264/AVC video streaming on WCDMA networks.
- Creator
- Murillo, Carlos A., Florida Atlantic University, Iskander, Cyril-Daniel, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
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This thesis presents the simulation based performance evaluation on the transmission of multimedia services (H.264/AVC video streaming) to a mobile user over a packet-switched wireless network based on the WCDMA standard. The H.264/AVC refers to the codec, which is used as the main tool for video compression. It enables the transport of high bandwidth video data over Third Generation (3G) wireless systems by offering a high video compression rate, adaptability to the channel, and error...
Show moreThis thesis presents the simulation based performance evaluation on the transmission of multimedia services (H.264/AVC video streaming) to a mobile user over a packet-switched wireless network based on the WCDMA standard. The H.264/AVC refers to the codec, which is used as the main tool for video compression. It enables the transport of high bandwidth video data over Third Generation (3G) wireless systems by offering a high video compression rate, adaptability to the channel, and error resilience. It is transported using the RTP/UDP/IP protocol stack over the 3G wireless system. The WCDMA technology is simulated with special emphasis on the upper layers of the wireless channel. The performance of the WCDMA system is studied when transporting RTP/UDP/IP packets of H.264/AVC compressed video data under diverse configuration scenarios, namely, ARQ schemes and variable length of the transmitted frame at the link layer. These components of a packet-switched streaming service are integrated into a software simulation model, which is used to evaluate the end-to-end H.264/AVC video quality in a WCDMA wireless network.
Show less - Date Issued
- 2005
- PURL
- http://purl.flvc.org/fcla/dt/13291
- Subject Headings
- Wireless communication systems, Mobile communication systems, Global system for mobile communications, Code division multiple access, Streaming technology (Telecommunications)
- Format
- Document (PDF)
- Title
- Stochastic optimization of energy for multi-user wireless networks over fading channels.
- Creator
- Wang, Di, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
Wireless devices in wireless networks are powered typically by small batteries that are not replaceable nor recharged in a convenient way. To prolong the operating lifetime of networks, energy efficiency is indicated as a critical issue and energy-efficient resource allocation designs have been extensively developed. We investigated energy-efficient schemes that prolong network operating lifetime in wireless sensor networks and in wireless relay networks. In Chapter 2, the energy-efficient...
Show moreWireless devices in wireless networks are powered typically by small batteries that are not replaceable nor recharged in a convenient way. To prolong the operating lifetime of networks, energy efficiency is indicated as a critical issue and energy-efficient resource allocation designs have been extensively developed. We investigated energy-efficient schemes that prolong network operating lifetime in wireless sensor networks and in wireless relay networks. In Chapter 2, the energy-efficient resource allocation that minimizes a general cost function of average user powers for small- or medium-scale wireless sensor networks, where the simple time-division multiple-access (TDMA) is adopted as the multiple access scheme. A class of Ç-fair cost-functions is derived to balance the tradeoff between efficiency and fairness in energy-efficient designs. Based on such cost functions, optimal channel-adaptive resource allocation schemes are developed for both single-hop and multi-hop TDMA sensor networks. In Chapter 3, optimal power control methods to balance the tradeoff between energy efficiency and fairness for wireless cooperative networks are developed. It is important to maximize power efficiency by minimizing power consumption for a given quality of service, such as the data rate; it is also equally important to evenly or fairly distribute power consumption to all nodes to maximize the network life. The optimal power control policy proposed is derived in a quasi-closed form by solving a convex optimization problem with a properly chosen cost-function. To further optimize a wireless relay network performance, an orthogonal frequency division multiplexing (OFDM) based multi-user wireless relay network is considered in Chapter 4., In the OFDM approach, each subcarrier is dynamically assigned to a source- destination link, and several relays assist communication between pairs of source-destination over their assigned subcarriers. Using a class of Ç-fair cost-functions to balance the tradeoff between energy efficiency and fairness, jointly with optimal subcarrier and power allocation schemes at the relays. Relevant algorithms are derived in quasi-closed form. Lastly, the proposed energy-efficient schemes are summarized and future work is discussed in Chapter 5.
Show less - Date Issued
- 2011
- PURL
- http://purl.flvc.org/FAU/3322519
- Subject Headings
- Stochastic processes, Data processing, Wireless communication systems, Mathematical models, Computer network protocols, Signal processing, Digital techniques, Code division multiple access, Waveless division multiplexing, Orthogonalization methods
- Format
- Document (PDF)
- Title
- Studies on Stochastic Multi-user Scheduling in Wireless Communication.
- Creator
- Wang, Di, Morgera, Salvatore D., Wang, Xin, Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
We developed a cross layer design which combines retransmission diversity and multi-user diversity for wireless communication. To this end, a joint design of adaptive modulation and coding with retransmission-based automatic repeat request protocol is outlined. This design is applied to devise multi-user scheduling schemes, which can optimally capture the available multi-user and retransmission diversities. In addition, the proposed on-line scheduling algorithms can operate even when the...
Show moreWe developed a cross layer design which combines retransmission diversity and multi-user diversity for wireless communication. To this end, a joint design of adaptive modulation and coding with retransmission-based automatic repeat request protocol is outlined. This design is applied to devise multi-user scheduling schemes, which can optimally capture the available multi-user and retransmission diversities. In addition, the proposed on-line scheduling algorithms can operate even when the underl ying fading channel distribution is unknown, while asymptotically converging to the offline benchmark with guarantees on prescribed fairness and rate requirements. Numerical results are provided to verify the merits of our novel schemes for multi-user transmissions over Nakagami block fading channels.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/fau/fd/FA00012568
- Subject Headings
- Stochastic processes--Data processing, Wireless communication systems, Computer network protocols, Code division multiple access, Modulation (Electronics), Signal processing--Digital techniques
- Format
- Document (PDF)