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Shepherd, David Peter, i RSISE [sic]. "Optimisation of Iterative Multi-user Receivers using Analytical Tools". The Australian National University. Research School of Information Sciences and Engineering, 2008. http://thesis.anu.edu.au./public/adt-ANU20081114.221408.
Pełny tekst źródłaHijazi, Samer L. "Multi-user detection for multi-carrier communication systems". Diss., Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/147.
Pełny tekst źródłaYeh, Chen-Chu Alex. "Minimum-error-probability equalization and multi-user detection". Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/12994.
Pełny tekst źródłaSilva, Mário Marques da. "Multi-User Detection for DS-CDMA Systems". Master's thesis, Instituto Superior Técnico, 1999. http://hdl.handle.net/11144/349.
Pełny tekst źródłaAl-Iesawi, Salah. "Adaptive implementation of turbo multi-user detection architecture". Thesis, University of Newcastle Upon Tyne, 2012. http://hdl.handle.net/10443/1494.
Pełny tekst źródłaBaines, Steven John. "Linear multi-user detection in DS-CDMA cellular systems". Thesis, University of York, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263690.
Pełny tekst źródłaAbedi, Saied. "Genetic multi-user detection for code division multiple access systems". Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/843016/.
Pełny tekst źródłaFantuz, Mitchell. "Multi-User Detection of Overloaded Systems with Low-Density Spreading". Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39600.
Pełny tekst źródłaZhu, Weihua. "Blind Equalization and Multi-User Detection in Asynchronous Space-Time Coded CDMA System". Cincinnati, Ohio : University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1092948594.
Pełny tekst źródłaOkada, Hiraku, Peter M. Grant, Ian W. Band i Akira Ogawa. "Application of MMSE Multi-user Detection to CDMA Unslotted ALOHA System". IEEE, 2000. http://hdl.handle.net/2237/7806.
Pełny tekst źródłaIllangakoon, Chathura. "On joint source-channel decoding and interference cancellation in CDMA-based large-scale wireless sensor networks". IEEE, 2013. http://hdl.handle.net/1993/22019.
Pełny tekst źródłaHicks, James Edward. "Novel Approaches to Overloaded Array Processing". Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/28670.
Pełny tekst źródłaPh. D.
Annalingam, Dheveegar David. "Blind adaptive multi user interference cancellation detectors and antenna array for CDMA systems". Thesis, University of Sussex, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435615.
Pełny tekst źródłaMashwama, Derrick Bonginkosi. "Performance of turbo multi-user detectors in space-time coded DS-CDMA systems". Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/5169.
Pełny tekst źródłaIn this thesis we address the problem of improving the uplink capacity and the performance of a DS-CDMA system by combining MUD and turbo decoding. These two are combined following the turbo principle. Depending on the concatenation scheme used, we divide these receivers into the Partitioned Approach (PA) and the Iterative Approach (IA) receivers. To enable the iterative exchange of information, these receivers employ a Parallel Interference Cancellation (PIC) detector as the first receiver stage.
Kao, Johnny Wei-Hsun. "Methods of artificial intelligence for error control coding and multi-user detection". Thesis, University of Auckland, 2010. http://hdl.handle.net/2292/5962.
Pełny tekst źródłaSchepker, Henning F. [Verfasser]. "Compressive Sensing Multi-User Detection Approaches for Sporadic Communication / Henning F. Schepker". Aachen : Shaker, 2015. http://d-nb.info/1081885270/34.
Pełny tekst źródłaHsu, Kai-Chieh Frank. "High-performance vector processing for multi-user detection in spread-spectrum communication". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0015/MQ52998.pdf.
Pełny tekst źródłaKozal, Ahmed Sultan Bilal. "Multi user cooperation spectrum sensing in wireless cognitive radio networks". Thesis, Liverpool John Moores University, 2015. http://researchonline.ljmu.ac.uk/4474/.
Pełny tekst źródłaXu, Chong. "Reduced-complexity near-optimal Ant-Colony-aided multi-user detection for CDMA systems". Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/206015/.
Pełny tekst źródłaKhattak, Shahid. "Base station cooperation strategies for multi-user detection in interference limited cellular systems /". Dresden : Vogt, 2008. http://d-nb.info/990989542/04.
Pełny tekst źródłaVollmer, Marius [Verfasser]. "Efficient Linear Multi User Detection Techniques for Third Generation Mobile Radio Systems / Marius Vollmer". Aachen : Shaker, 2005. http://d-nb.info/1181619866/34.
Pełny tekst źródłaLI, XIANGTAO. "PERFORMANCE ANALYSIS OF DECORRELATING DETECTORS FOR DUAL-RATE SYNCHRONOUS DS/CDMA SYSTEMS OVER FREQUENCY-SELECTIVE RAYLEIGH FADING CHANNELS". University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1028644891.
Pełny tekst źródłaHusseini, Orabi Ahmed. "Multi-Modal Technology for User Interface Analysis including Mental State Detection and Eye Tracking Analysis". Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36451.
Pełny tekst źródłaBian, Yan Qing. "Advanced multi-user direct-sequence code division multiple access (DS-CDMA) detection techniques for cellular communications". Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398603.
Pełny tekst źródłaYeo, Hong Kwang. "Development and implementation of multi-user detection (MUD) strategies for shallow water acoustic network (SWAN) telemetry". Thesis, University of Newcastle upon Tyne, 2001. http://hdl.handle.net/10443/3131.
Pełny tekst źródłaWebber, Julian Leonard. "Performance enhancement of multi-user detectors for TD-CDMA by means of polarisation diversity and reduced computational complexity". Thesis, University of Bristol, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396658.
Pełny tekst źródłaGanhão, Francisco José Dinis de Sousa Fernandes. "Energy-efficient diversity combining for different access schemes in a multi-path dispersive channel". Doctoral thesis, Faculdade de Ciências e Tecnologia, 2014. http://hdl.handle.net/10362/12453.
Pełny tekst źródłaThe forthcoming generation of mobile communications, 5G, will settle a new standard for a larger bandwidth and better Quality of Service (QoS). With the exploding growth rate of user generated data, wireless standards must cope with this growth and at the same time be energy efficient to avoid depleting the batteries of wireless devices. Besides these issues, in a broadband wireless setting QoS can be severely affected from a multipath dispersive channel and therefore be energy demanding. Cross-layered architectures are a good choice to enhance the overall performance of a wireless system. Examples of cross-layered Physical (PHY) - Medium Access Control (MAC) architectures are type-II Diversity Combining (DC) Hybrid-ARQ (H-ARQ) and Multi-user Detection (MUD) schemes. Cross-layered type-II DC H-ARQ schemes reuse failed packet transmissions to enhance data reception on posterior retransmissions; MUD schemes reuse data information from previously collided packets on posterior retransmissions to enhance data reception. For a multipath dispersive channel, a PHY layer analytical model is proposed for Single-Carrier with Frequency Domain Equalization (SC-FDE) that supports DC H-ARQ and MUD. Based on this analytical model, three PHY-MAC protocols are proposed. A crosslayered Time Division Multiple Access (TDMA) scheme that uses DC H-ARQ is modeled and its performance is studied in this document; the performance analysis shows that the scheme performs better with DC and achieves a better energy efficiency at the cost of a higher delay. A novel cross-layered prefix-assisted Direct-Sequence Code Division Multiple Access (DS-CDMA) scheme is proposed and modeled in this document, it uses principles of DC and MUD. This protocol performs better by means of additional retransmissions, achieving better energy efficiency, at the cost of higher redundancy from a code spreading gain. Finally, a novel cross-layered protocol H-ARQ Network Division Multiple Access (H-NDMA) is proposed and modeled, where the combination of DC H-ARQ and MUD is used with the intent of maximizing the system capacity with a lower delay; system results show that the proposed scheme achieves better energy efficiency and a better performance at the cost of a higher number of retransmissions. A comparison of the three cross-layered protocols is made, using the PHY analytical model, under normalized conditions using the same amount of maximum redundancy. Results show that the H-NDMA protocol, in general, obtains the best results, achieving a good performance and a good energy efficiency for a high channel load and low Signal-to-Noise Ratio (SNR). TDMA with DC H-ARQ achieves the best energy efficiency, although presenting the worst delay. Prefix-assisted DS-CDMA in the other hand shows good delay results but presents the worst throughput and energy efficiency.
Wang, Beibei. "Improved Statistical Interference Suppression Techniques in Single and Multi-rate Direct Sequence Spread Spectrum Code Division Multiple Access Systems". Ohio University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1173119961.
Pełny tekst źródłaNguyen, Anh-Minh Ngoc. "High-Quality Detection in Heavy-Traffic Avionic Communication System Using Interference Cancellation Techniques". Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29069.
Pełny tekst źródłaPh. D.
Çelebi, Mehmet Bahadır. "On the Improvement of the Capacity of the Heterogeneous Networks with Link-Level and System-Level Approaches". Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5353.
Pełny tekst źródłaOllivier, Benjamin. "Acoustique longue portée pour transmission et localisation de signaux". Thesis, Télécom Bretagne, 2016. http://www.theses.fr/2016TELB0413/document.
Pełny tekst źródłaThere is an increasing interest in underwater positioning system in industry (off-shore, military, and biology). In order to localize a receiver relative to a grid of transmitters, thanks to the knowledge of positions and transmission time, it needs to detect each signal and estimate the TOA (Time Of Arrival). Thus, a range between a transmitter and receiver can be deduced by estimation of TOA. When receiver knows three ranges at least, it can deduce its position by triangulation. This work takes into account signal detection, and waveform choice. Detection method, based on matched filter, needs to be robust face to propagation channel (transmission loss, multi-paths) and to the system (multi-users environment). Moreover, the detection structure, being a combination of binary hypothesis testing, must work in real time. In a CDMA context which requires to distinguish each transmitter, the FHSS (Frequency Hopped Spread Spectrum) modulation, allocating one code per user, is adapted. FHSS signals performance, depending of the number of frequency shifts N and the time-bandwidth product, are analyzed from detection criterion point of view. Moreover, detection method and adapted signal is tested in a shallow water environment.The research was supported by ALSEAMAR and DGA-MRIS scholarship
Fares, Fares. "Traitement des signaux Argos 4". Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0024/document.
Pełny tekst źródłaIn our thesis, we investigate the application of multi user detection techniques to a Low Polar Orbit (LPO) satellite used in the Argos system. Argos is a global satellite-based location and data collection system dedicated for studying and protecting the environment. User platforms, each equipped with a Platform Transmitter Terminal (PTT), transmit data messages to a 850 km LPO satellite. An ARGOS satellite receives, decodes, and forwards the signals to ground stations. All PTTs transmit at random times in a 100 kHz bandwidth using different carrier frequencies. The central carrier frequency f0 is 401.65 MHz. Due to the relative motion between the satellite and the platforms, signals transmitted by PTTs are affected by both a different Doppler shift and a different propagation delay. Thus, the Argos satellite receives overlapping signals in both frequency and time domains inducing Multiple Access Interference (MAI). One common approach to mitigate the MAI problem is to implement Multi User Detection (MUD) techniques at the receiver. To tackle this problem, several MUD techniques have been proposed for the reception of synchronous and asynchronous users. In particular, the Successive Interference Cancelation (SIC) detector has been shown to offer a good optimality-complexity trade-off compared to other common approaches such as the Maximum Likelihood (ML) receiver. In an Argos SIC receiver, users are decoded in a successive manner, and the signals of successfully decoded users are subtracted from the waveform before decoding the next user. This procedure involves a parameter estimation step and the impact of erroneous parameter estimates on the performance of Argos SIC receiver has been studied. Argos SIC receiver has been shown to be both robust to imperfect amplitude and phase estimation and sensitive to imperfect time delay estimation. The last part of our work focuses on the implementation of digital estimators for the Argos system. In particular, we propose a time delay estimator, a frequency estimator, a phase estimator and an amplitude estimator. These estimators are derived from the ML principle and they have been already derived for the single user transmission. In our work, we adapt successfully these estimators for the multi user detector case. These estimators use the Non Data Aided (NDA) cases in which no a priori information for the transmitted bits is required. The performance of these different estimators are compared to the Cramer Rao Bound (CRB) values. Finally, we conclude in our work by showing the different results obtained during this dissertation. Also, we give some perspectives for future work on Argos system
Poliak, Sebastián. "Mobilní aplikace využívající hlubokých konvolučních neuronových sítí". Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2018. http://www.nusl.cz/ntk/nusl-385895.
Pełny tekst źródłaNgo, Khac Hoang. "Non-coherent wireless communications : fundamental limits and system design". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC031.
Pełny tekst źródłaIn wireless communication over fading channels, especially multiple-antenna communication, the instantaneous knowledge of channel coefficients, so-called channel state information (CSI), is critical because it enables to adapt the transmission and reception to current channel conditions. The communication with a priori CSI at the receiver is said to be coherent. In practice, however, CSI is not granted for free prior to communication and needs to be estimated at a cost that should not be ignored, especially in a highly mobile environment. Thus, communication without a priori CSI, also known as noncoherent communication, is a more practical and general framework. This thesis contributes to the understanding of the theoretical limits of noncoherent communications, as well as the design of a practical noncoherent communication system in block fading. We consider three scenarios: the point-topoint (P2P) channel, the multiple-access channel (MAC), and the broadcast channel (BC).In the first part, we study the fundamental limits of noncoherent communications in terms of achievable data rate and degrees of freedom (DoF). We consider generic block fading in which the channel has finite differential entropy and finite second moment. First, we derive the optimal DoF for the noncoherent multiple-input multiple-output (MIMO) P2P channel by using the duality approach to bound the input-output mutual information. Second, using a similar duality approach, we derive the optimal DoF region for the two-user noncoherent single-input multiple-output (SIMO) MAC, which can be achieved by time sharing between simple pilot-based schemes. Third, we derive achievable rate and DoF regions for the noncoherent MIMO BC with spatially correlated fading by exploiting the transmit correlation diversity, which is the difference between the correlation experienced by different users. In doing so, we carefully design pilot-based transmission schemes based on rate splitting, product superposition, and a combination of them to effectively transmit signals in both the common and mutually exclusive parts of the correlation subspaces. In the second part, we design the constellation and efficient detection schemes for noncoherent communications over Rayleigh block fading channel. First, we propose a structured Grassmannian constellation for the SIMO P2P channel that is simple to generate, has high packing efficiency, admits a simple yet effective binary labeling, and allows for efficient soft and hard detection. Second, we investigate joint constellation design for the MIMO MAC. We introduce some simple and effective design criteria so as to minimize the joint detection error, and propose some simple constellation constructions. Third, we propose a noncoherent multi-user soft detection scheme for the SIMO MAC in spatially correlated Rayleigh fading based on expectation propagation approximate inference. This scheme has polynomial complexity in the channel dimension while producing accurate approximate per-user posterior marginals leading to near-optimal error performance
Wu, sheng-quan, i 吳昇銓. "Orthogonal Decision-Feedback Detector (ODFD) for CDMA Multi-user Detection". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/67899744505316790570.
Pełny tekst źródła國立中興大學
電機工程學系
89
We propose a multi-user detection scheme for downlink channel and uplink link channel, including multi-path effect. The orthogonal decision-feedback detector (ODFD) employs a match filter bank matching to a set of orthogonal sequences, which are generating by Gram-Schmidt orthogonalisation procedure based on spreading codes. The ODFD algorithm involves only the orthonormal coefficient matrix, which require no frequent recalculations even when system parameters change. Successive decision-feedback detection is performed immediately at the output of the ODFD match filter bank without the transform matrix, which requires in the DDFD. For downlink channel, we considering the multi-path and fading effect, and we assume that there are 12 kinds of channels to simulation. To improve the system performance, two different types of RAKE receiver structures, equal gain combining RAKE and maximum ratio combining RAKE, are also considered for CDMA systems to mitigate multi-path fading effects of mobile channels. For uplink channel, the assumption are the same with downlink channel, the different is just the users are asynchronous each other. And in this thesis we comparison structure and algorithm complexity between ADDFD and AODFD.
Wu, sheng-quan, i 張亞寧. "Orthogonal Decision-Feedback Detector (ODFD) for CDMA Multi-user Detection". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/05050716608149895145.
Pełny tekst źródła國立中興大學
電機工程學系
89
We propose a multi-user detection scheme for downlink channel and uplink link channel, including multi-path effect. The orthogonal decision-feedback detector (ODFD) employs a match filter bank matching to a set of orthogonal sequences, which are generating by Gram-Schmidt orthogonalisation procedure based on spreading codes. The ODFD algorithm involves only the orthonormal coefficient matrix, which require no frequent recalculations even when system parameters change. Successive decision-feedback detection is performed immediately at the output of the ODFD match filter bank without the transform matrix, which requires in the DDFD. For downlink channel, we considering the multi-path and fading effect, and we assume that there are 12 kinds of channels to simulation. To improve the system performance, two different types of RAKE receiver structures, equal gain combining RAKE and maximum ratio combining RAKE, are also considered for CDMA systems to mitigate multi-path fading effects of mobile channels. For uplink channel, the assumption are the same with downlink channel, the different is just the users are asynchronous each other. And in this thesis we comparison structure and algorithm complexity between ADDFD and AODFD.
Huang, Zi-Yi, i 黃子益. "An Improved Multi-User Detector for Ds-CDMA system". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/71982824880834813076.
Pełny tekst źródła國立中山大學
電機工程學系研究所
86
Direct-sequence code-division multiple access (DS-CDMA) is one of several methods of multiplexing wireless users. In CDMA, all users use the same carrier frequency and may transmit signals simultaneously by assigning a distinct signature sequence to each user. The detector receives a signal composed of the sum of all users' signals, which overlap in time and frequency.A conventional DS-CDMA system treats each user separately as a signal, with the other users considered as multiple access interference (MAI) and is highly vulnerable to tjhe near-far effect. The optimum maximum likelihood detector jointly extracts user's messages by solving an optimization problem. Although the optimum detector improves the system performance significantly, the associated computational complexity increases exponentially with the number of users [7], which prohibits its practical use. Therefore, many suboptimum detectors, like MMSE detector, decorrelator detector and etc. have been proposed [9]-[18].In this paper, we use adaptive algorthm to implement the MMSE detector and use decision feedback structure to improve it. We compare the bit error rate of the proposed detector with those of the conventional, decorrelator. and MMSE detetors. The performance for relatively weak user by using the proposed adaptive decision feedback detector has been significantly improved.
Li, Tzung-Cheng, i 李宗晟. "An Improved PDA Multi-User Detector for DS-CDMA UWB Systems". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/65927769982615811037.
Pełny tekst źródła國立中山大學
電機工程學系研究所
93
Ultra-Wideband technology has attracted interests of the researchers and commercial groups due to its advantage of high data rate, low complexity and low power consumption. The direct-sequence code division multiple access ultra wideband system (DS-CDMA UWB) is one of the proposal of IEEE 802.15.3a standard. By combing the power of both UWB and DS-CDMA techniques, the system could construct multiple access architecture using direct sequence method. In multi-user environment, the major problem of the receiver designing of conventional DS-CDMA system is multiple access interference(MAI). In DS-CDMA UWB system, the transmitted signal were interfered by inter-symbol interference(ISI) and neighbor symbol interference because of the multi-path channel characteristic. In this thesis, we use the training method to get the spreading waveform influenced by multi-path. Based on the information of spreading waveform, we use the block method to reformulate the received signal. We can separate the interference into multiple access interference and neighbor symbol interference. With Combining the interference cancellation, probabilistic data association (PDA) filter and sliding window techniques, we could eliminate the interference. In the computer simulation section, we compare the detection performance of sliding window PDA detector with conventional detector, and the simulation result shows that the improved PDA detector has better performance than others.
Shepherd, David Peter. "Optimisation of Iterative Multi-user Receivers using Analytical Tools". Phd thesis, 2008. http://hdl.handle.net/1885/49357.
Pełny tekst źródłaLin, Shin-Ji, i 林信吉. "The improvement on the performance of the Group MMSE Multi-user Detector". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/66439102764073978225.
Pełny tekst źródła國立臺北科技大學
電機工程系碩士班
91
The goal of this thesis is to investigate the Group MMSE multi-user detector technology applied on the DS-CDMA system and MT-CDMA system and to improve the performance of these systems. Since the complexity of the MMSE multi-user detector is related to the inverse matrix operation, in order to reduce the complexity and increase the practicality, the Group MMSE detector has been proposed. However, while the Group MMSE detector does reduce the complexity, it also increases the bit error rate. This thesis proposes two methods to lower the bit error rate for the Group MMSE detector. The first method is to apply the correlation matrix for choosing the user’s group in the original DS-CDMA system, so that the users with higher cross correlation are grouped together and those with lower cross correlation are allocated in the different groups. For the second method, to further reduce the interference of different groups, we apply the Group MMSE detector on the modified MT-CDMA structure. We make use of the multi-tone property of the MT-CDMA system, and let users of different groups propagate on the different carriers. By orthogonality of the carrier, we can reduce the mutual interferences between user groups, and thus lower the bit error rate.
Lin, Kowei, i 林克威. "A Multi-user Detector for Synchronous CDMA communication Systems Based on EM Algorithm". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/27417219217471859878.
Pełny tekst źródła長庚大學
電機工程研究所
89
The maximum likelihood detection of superimposed signal in direct sequence code division multiple access (DS-CDMA) has a computational complexity, increased in exponential with numbers of active users, and its implementation is prohibitive even for a moderate number of users. Some research has applied expectation maximization (EM) algorithm to decompose the multiuser detection problem into a series of single-user problems, and presents an iterative computational efficient algorithm for detection of signals in synchronous CDMA system. The EM-based detector estimates each user’s signal to interference ratio (SIR) only by the property of cross-correlation of different users, but it does not reflect the actual SIR of each user. We propose a new detector, without increasing additional hardware circuit, can estimate signal to interference ratio (SIR) of different users directly by each user’s match filter output. Within estimated SIR, new detector changes its parameter dynamically to increase the performance of detection. Simulation result also shows that when near-far effect occurs or the power control is not perfect, the new detector can maintain performance without estimating signal amplitude of each user.
Yang, Shih-Yang, i 楊石陽. "A Multi-user Detector Based on EM Algorithm for Synchronous CDMA Communication Systems Over". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/28896865849098321333.
Pełny tekst źródła長庚大學
電機工程研究所
90
The maximum likelihood detection of superimposed signal in direct sequence code division multiple access (DS-CDMA) has a computational complexity, increased in exponential with numbers of active users, and its implementation is prohibitive even for a moderate number of users. Some research has applied expectation maximization (EM) algorithm to decompose the multi-user detection problem into a series of single-user problems, and presents an iterative computational efficient algorithm for detection of signals in synchronous CDMA system. However the EM-based detector estimates each user’s signal to interference ratio (SIR) only by the property of cross-correlation of different users, but it does not reflect the actual SIR of each user. So,we propose a new algorithm called AISI algorithm ( Approximate ISR estimator by Side-lobe Information algorithm ) for improving the EM-based detector , The AISI algorithm can estimate signal to interference ratio (SIR) of different users directly by each user’s despreading filter output without increasing additional hardware circuit,. Within estimated SIR, new detector changes its parameter dynamically to increase the performance of detection. Our new detector also adds the novel idea of improved PIC that has different weight in each stage. By combining these two opinions,New detector changes its parameter dynamically in each stage to increase performance .At the end of this paper; we compare several kinds of multi-user detector. Simulation result also shows that when near-far effect occurs or not, the new detector still can have better performance than others.
Lan, Hao-Yu, i 藍浩佑. "Low Complexity Multi-User Detector Design for Sparse Code Multiple Access in 5G networks". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8qnx69.
Pełny tekst źródła國立臺灣大學
電子工程學研究所
106
Massive Machine Type Communications (mMTC) is one of the three major types of 5G use cases. In the coming era of Internet of Things (IoT), all devices will be connected. Currently there are several proposals for achieving this objective in the 3GPP standard meetings. One promising technology, called sparse code multiple access (SCMA), implements uplink grant-free non-orthogonal multiple access (NOMA) for mMTC networks. SCMA is derived from the low-density spread OFDM (LDS-OFDM) and has the advantages of low signaling overhead, low transmission latency, and high spectral efficiency. In this thesis, we focus on low complexity and high performance multiuser receiver design for SCMA systems. In the Chapter 3, we introduce the principle of SCMA and LDS systems and conduct physical layer simulation for AWGN channel and uplink multipath fading channel. To start with, we design the SCMA codebook and low-density signature (LDS) and analyze their BER performance and convergence behavior. It is worth mentioning that different spreading length, overloading ratio, receiver diversity and near-far effect are also taken into account in our analysis. In the Chapter 4, we design the low complexity multiuser detection for the basic SCMA system, including the factor graph and the message passing algorithm. To improve the convergence rate and reduce the MPA complexity of later iterations, SINR based Serial MPA (SS-MPA) and codebook cardinality reduction based MPA (CCR-MPA) are proposed. To validate the effectiveness of these two methods, we conduct simulations to show that SS-MPA converges faster than traditional methods on the uplink multipath fading channel and CCR-MPA reduces 50% to 80% complexity of conventional MPA while the characteristic of fixed complexity is retained to facilitate the realization of the hardware implementation. At the end of the thesis, we design the cost-efficient multiuser receiver for turbo sparse code multiple access (Turbo-SCMA) system. By iterative detection and decoding (IDD) and our proposed methods, the receiver achieves high BER performance and reduces a lot of memory usages and computational complexity compared with state state of the art method.
Lee, Zheng-Xiu, i 李政修. "Performance Analysis and Improvement of Multi-user Detector Using Probabilistic Data Association in CDMA systems". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/2v45m8.
Pełny tekst źródła國立臺北科技大學
電機工程系所
93
The main purpose of this thesis is to improve the performance of multi-user detector using probabilistic data association in CDMA systems by reducing its computational complexity. The performance of multi-user detector using probabilistic data association is close to optimal multi-user detector, but its computational complexity is still higher than the linear MMSE multi-user detector. To reduce its computational complexity, the different initial settings of probabilistic data association are used in this thesis to analyze the effects of convergence time of this multi-user detector in synchronous and asynchronous CDMA systems. A new method has been proposed in this thesis. We set the initial values of probabilistic data association by using the soft decision of the output signals in MMSE or decorrelating multi-user detectors. It can reduce the computational complexity while maintain the same bit error rate in the CDMA systems. Finally, the new proposed method and other methods of fixed initial values of probability are applied to both the DS-CDMA system and slowly fading flat channel MC-CDMA system to verify its performance.
Fu, Ray-Hsiang, i 傅瑞翔. "Multi-user Detector for DS-UWB System Using Constricted Selection Rake Receiver and Genetic Algorithms". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/r774q9.
Pełny tekst źródła國立臺北科技大學
電機工程系所
95
DS-UWB is one major technology employed in UWB system. However, for the multi-user application the multiple access interference (MAI) due to imperfect orthogonality between spreading codes induced by UWB dense multi-path degrades system performance. Though optimum multi-user detector (OMD) can achieve remarkable performance, its computational complexity is too high to implement. Therefore, many sub-optimal multi-user detectors (MUDs) have been proposed to compromise system performance and complexity, such as the genetic algorithm-based MUD (GA-MUD). Previous work combining the partial rake receiver (p-rake) and GA-MUD has been proposed, but its performance is still not attractive. Therefore, a CSRGA-MUD that combines the constricted selection rake receiver (cs-rake) and GA-MUD is proposed to improve BER performance further. Moreover, for seeking the best trade-off between BER performance and computational complexity, a CSRGA-MUD with lower computational complexity is also proposed.
Wang, Qingsheng. "Power and performance trade-off in DS-CDMA receivers based on adaptive LMS-MMSE multi-user detector". Thesis, 2003. http://hdl.handle.net/10413/4212.
Pełny tekst źródłaThesis (M.Sc.Eng.)-University of Natal, Durban, 2003.
Chin, Wan-Ying, i 秦婉瑛. "Noncoherent multi-user detection". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/896qh6.
Pełny tekst źródła國立中央大學
通訊工程學系
107
Wireless communications is required to transmit quantity of data more and more. An important studying topic is how to transmit the same quantity of data in a shorter period of time. Recently, two-way relaying is a popular subject, where two terminal nodes transmit to each other with the help of the relay node. Two-phase two-way relaying (TPTWR) using physical-layer coding is a bandwidth efficient technique. Several TPTWR schemes using differential phase-shift keying (DPSK) which avoid the rate loss due to pilot symbols were proposed. In this thesis ,we first focus on differential MPSK for TPTWR using decode and forward technique. We propose that the signal constellation of one terminal is the signal constellation of the other terminal rotated by an angle. For the noncoherent maximum-likelihood detector at the relay, we propose a distance measure for the transmitted signals of the two terminals. Based on the proposed distance, we find the optimal angles for both cases of using decision feedback or not. Then the noncoherent two-user detection at the relay is extended as noncoherent three-user detection. We apply these results to NOMA(non-orthogonal multiple access), and compare it with OMA(orthogonal multiple access) by computer simulation.
Wang, Jinghan. "Multi-user Detection Techniques in Multi-antenna Systems". 2004. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2106200410081500.
Pełny tekst źródłaWang, Jinghan, i 王璟瀚. "Multi-user Detection Techniques in Multi-antenna Systems". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/61864350144676531457.
Pełny tekst źródła國立臺灣大學
電信工程學研究所
92
In the thesis, we discuss several multi-antenna techniques in a wireless communication system. First, we consider the communication between a single transmitter and a single receiver by utilizing multiple antennas. Next, we discuss the multiuser detection (MUD) techniques in a CDMA system, and then we propose that the multiuser detection techniques can also be utilized in a multi-antenna system.
Wen-Feng, Hu. "Performance Comparison of Multi-user Detection and Multi-Antenna Technique for Multi-user DS-CDMA UWB System". 2005. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-1507200511223500.
Pełny tekst źródła