Dissertations / Theses on the topic 'Rake receivers'
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1
Gkiokas, Stamatios. "Successive interference cancellation in rake receivers for CDMA signals." Thesis, Monterey, Calif. : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Jun/09Jun%5FGkiokas.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 2009.Thesis Advisor(s): Ha, Tri ; Robertson, Ralph C. "June 2009." Description based on title screen as viewed on July 13, 2009. Author(s) subject terms: SIIC, W-CDMA, WID. Includes bibliographical references (p. 59). Also available in print.
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Syed, Imtiaz Husain Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Channel shortening equalizers for UWB receiver design simplification." Publisher:University of New South Wales. Electrical Engineering & Telecommunications, 2008. http://handle.unsw.edu.au/1959.4/41473.
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Ultra Wideband (UWB) communication systems occupy large bandwidths with very low power spectral densities. This feature makes UWB channels highly rich in multipaths. To exploit the temporal diversity, a UWB receiver usually incorporates Rake reception. Each multipath in the channel carries just a fraction of the signal energy. This phenomenon dictates a Rake receiver with a large number of fingers to achieve good energy capture and output signal to noise ratio (SNR). Eventually, the Rake structure becomes very complex from analysis and design perspectives and incurs higher manufacturing cost. The first contribution of this thesis is to propose channel shortening or time domain equalization as a technique to reduce the complexity of the UWB Rake receiver. It is analyzed that most of the existing channel shortening equalizer (CSE) designs are either system specific or optimize a parameter not critical or even available in UWB systems. The CSE designs which are more generic and use commonly critical cost functions may perform poorly due to particular UWB channel profiles and related statistical properties. Consequently, the main contribution of the thesis is to propose several CSE designs to address the specific needs of UWB systems. These CSE designs not only exploit some general but also some UWB specific features to perform the task more efficiently. The comparative analysis of the proposed CSEs, some existing designs and the conventional Rake structures leads towards the conclusion. It is finally shown that the use of CSE at the receiver front end greatly simplifies the Rake structure and the associated signal processing.
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Gaur, Sudhanshu. "Analysis of Advanced Diversity Receivers for Fading Channels." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9670.
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Proliferation of new wireless technologies has rekindled the interest on the design, analysis and implementation of suboptimal receiver structures that provide good error probability performance with reduced power consumption and complexity particularly when the order of diversity is large. This thesis presents a unified analytical framework to perform a trade-off study for a class of hybrid generalized selection combining technique for ultra-wideband, spread-spectrum and millimeter-wave communication receiver designs.
The thesis also develops an exact mathematical framework to analyze the performance of a dual-diversity equal gain combining (EGC) receiver in correlated Nakagami-m channels, which had defied a simple solution in the past. The framework facilitates efficient evaluation of the mean and variance of coherent EGC output signal-to-noise ratio, outage probability and average symbol error probability for a broad range of digital modulation schemes. A comprehensive study of various dual-diversity techniques with non-independent and non-identical fading statistics is also presented.
Finally, the thesis develops some closed-form solutions for a few integrals involving the generalized Marcum Q-function. Integrals of these types often arise in the analysis of multichannel diversity reception of differentially coherent and noncoherent digital communications over Nakagami-m channels. Several other applications are also discussed.Master of Science
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D'Amours, Claude. "Differential and coherent RAKE receivers for DS-CDMA in frequency-selective Rayleigh fading channels." Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/10753.
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The performance of digital communications over frequency-selective Rayleigh fading channels can be quite poor, thus diminishing, the capacity of a DS-CDMA system. This thesis compares differential detection, multiple symbol differential detection and pilot symbol-aided coherent detection of a direct-sequence spread spectrum signal for this channel. Diversity reception is obtained through RAKE reception, and both equal gain and maximal gain diversity combining are considered. The improvement provided by some error correcting convolutional codes arid interleaving are also studied.
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Kowalske, Kyle E. "Performance of coherent and noncoherent RAKE receivers with convolutional coding ricean fading and pulse-noise interference." Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1557.
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Approved for public release, distribution is unlimitedThe performance of coherent and noncoherent RAKE receivers over a fading channel in the presence of pulse-noise interference and additive white Gaussian noise is analyzed. Coherent RAKE receivers require a pilot tone for coherent demodulation. Using a first order phase-lock-loop to recover a pilot tone with additive white Gaussian noise causes phase distortions at the phase-lock-loop output, which produce an irreducible phase noise error floor for soft decision Viterbi decoding. Both coherent and noncoherent RAKE receivers optimized for additive white Gaussian noise perform poorly when pulse-noise interference is present. When soft decision convolutional coding is considered, the performance degrades as the duty cycle of the pulse-noise interference signal decreases. The reverse is true for hard decision Viterbi decoding, since fewer bits experience interference and bit errors with high noise variance cannot dominate the decision statistics. Soft decision RAKE receiver optimized for pulse-noise interference and additive white Gaussian noise performed the best for both the coherent and noncoherent RAKE receivers. This receiver scales the received signal by the inverse of the variance on a bit-by-bit basis to minimize the effect of pulse-noise interference. The efficacy is demonstrated by analytical results, which reveal that this receiver reduces the probability of bit error down to the irreducible phase noise error floor when pulse-noise interference is present. This demonstrates how important it is to design the receiver for the intended operational environment.
Civilian, Department of Defense
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Duran, Omer Agah. "Multiuser Receivers For Cdma Downlink." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609953/index.pdf.
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In this thesis, multiuser receivers for code division multiple-access (CDMA) downlink are studied under frequency selective fading channel conditions. The receivers investigated in this thesis attempt to estimate desired symbol as a linear combination of chip-rate sampled received signal sequence. A common matrix-vector representation of signals, which is similar to the model given by Paulraj et. al. is constructed in order to analyze the receivers studied in this thesis.
Two receivers already well known in the literature are introduced and derived by using the common signal model. One of the receivers uses traditional matched filter and the other uses symbol-level linear minimum mean square error (MMSE) estimation. The receiver that uses traditional matched filter, also known as the conventional RAKE receiver, benefits from time diversity by combining the signal energy from multiple paths. The conventional RAKE receiver is optimal when multiple-access interference (MAI) is absent. Linear MMSE based receivers are known to suppress MAI and to be more robust to noise enhancement. The optimal symbol-level linear MMSE based receiver requires inversion of large matrices whose size is determined by either number of active users or spreading factor. These two parameters can be quite large in many practical systems and hence the computational load of this receiver can be a problem.
In this thesis, two alternative low-complexity receivers, which are chip-level linear MMSE equalizer proposed by Krauss et. al. and interference-suppressing RAKE receiver proposed by Paulraj et. al., are compared with the linear full-rank MMSE based receiver and with the conventional RAKE receiver in terms of bit-error-rate performance. Various simulations are performed to evaluate the performance of the receivers and the parameters affecting the receiver performance are investigated.
7
Kowalske, Kyle. "Performance of coherent and noncoherent RAKE receivers with convolutional coding ricean fading and pulse-noise interference /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FKowalske.pdf.
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Thesis (Doctor of Philosophy in Electrical Engineering)--Naval Postgraduate School, June 2004.Thesis advisor(s): Clark Robertson. Includes bibliographical references (p. 85-87). Also available online.
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Patwari, Neal. "Measured and Modeled Time and Angle Dispersion Characteristics of the 1.8 GHz Peer-to-Peer Radio Channel." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/32201.
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In an extensive outdoor propagation study, low antenna heights of
1.7 m are used at both the transmitter and the receiver to measure
over 3500 wideband power-delay profiles (PDPs) of the channel for
a peer-to-peer communications system. Rural and urban areas are
studied in 22 different transmitter-receiver links. The results
are used to characterize the narrowband path loss, mean delay,
root-mean-square (RMS) delay spread, and timing jitter of the
peer-to-peer wideband channel. Small-scale fading characteristics are
measured in detail by measuring and analyzing 160 PDPs within each
local area. This thesis shows the measurement setup for the
calculation of fading rate variance and angular spread and reports
the first known attempt to calculate angular spread from track
power measurements. New analysis presented in this thesis shows
the effect of measurement error in the calculation of angular
spread. The expected characteristics of angular spread are
derived using two different angle-of-arrival (AOA) models from the
literature. Measurement results show initial validation of
Durgin's angular spread theory. A new measurement-based algorithm
for simulating wideband fading processes is developed and
implemented. This simulation technique shows promise in the
simulation of high-bit rate peer-to-peer radio communication
systems.Master of Science
9
Striglis, Stavros. "A multistage RAKE receiver for CDMA systems." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/42211.
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This thesis proposes a multistage RAKE receiver for use at the base station of a Code Division Multiple Access (CDMA) cellular communications system. This receiver combines the interference rejection capability of multiuser receivers with the robust performance of a RAKE receiver in the presence of multipath interference. Unlike previous multiuser receiver designs, this multistage RAKE receiver requires no a priori information about the time-vary multipath radio channel.
The thesis presents a mathematical description of the multistage receiver, and a software simulation of the receiver performance. A wide range of channel models are considered which include the effects of Gaussian noise, multipath propagation, imperfect power control and multiple access interference for the reverse link CDMA channel. Under a wide range of conditions, the multistage RAKE receiver is able to support two to three times as many users as a conventional single stage RAKE receiver. The receiver is also shown to be robust to the near-far problem.Master of Science
10
Murugesapillai, Navamshan. "The performance of the generalized RAKE (G-RAKE) receiver in a WCDMA-HSDPA scenario." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/26989.
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The High-Speed Downlink Packet Access (HSDPA) is a packet-based data service for increased data speed over WCDMA downlink. At high-speed data rate, advanced receivers are needed to realize a reasonable bit error performance.
This thesis studies the link-level performance of the G-RAKE receiver for the HSDPA and ways to reduce the receiver's complexity. Unlike the conventional RAKE receiver, the G-RAKE receiver suppresses interference caused by frequency-selective fading channels by accounting for coloured noise found in the fingers' output. Thus, G-RAKE optimizes the placement of fingers and the weighting coefficients in the Maximum Likelihood formulation.
In this thesis, performance of the G-RAKE is evaluated via simulations for both static and realistic multipath fading channels described in the literature. According to simulations, G-RAKE receiver compensates for the performance loss experienced by RAKE receivers when the user equipment becomes interference limited.
In G-RAKE receiver, calculating the weighting coefficients, which involves inverting the channel impairment matrix, is an expensive operation. It is shown that the complexity and processing time of this operation and, hence, of the overall receiver can be reduced with the Conjugate Gradient or Preconditioned Conjugate Gradient methods.
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Ansari, Muhammad Adeel. "TDMA for Low Sampling Rate IR-UWB Receivers." Licentiate thesis, KTH, Kommunikationssystem, CoS, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96694.
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In UWB communication sampling plays a key role in detection of the transmitted data. There are various methods of data transmission and detection at the receiver. Mostly, the detection methods are based on frequency domain methods. The popular method to lower the sampling rate is the sub-sampling technique, based on frequency of the transmitted signal. A special method like orthogonal frequency division multiplexing (OFDM) is needed to reduce inter symbol interference for a frequency based method. The power consumption associated with higher sampling rates is also a big challenge. Therefore some simple techniques are required to detect data on lower sampling rates without ISI in the multiple user environments and with lower power consumption. If selection of the sampling frequency would be flexible to detect data from multiple users then it could relax the UWB receiver design requirements. In this thesis we developed a transmission and reception methodology with reduced sampling frequency for data detection. In the proposed work, transmitted data is distributed using TDMA frames for all users within fixed time slots for each user. The TDMA technique is being used to achieve low sampling rates and to avoid multiple access interference (MAI). The sampling rate to detect the data of each user can be selected according to number of users and transmission bandwidth. For this purpose each data bit of a user is arranged once in a transmission frame. The data can be detected on frame repetition rate depends on the total number of users. The data of each user can be accessed directly by calculating the total time of each user place within each frame. Since each data bit of one user occurs once in a frame therefore it could be claimed that ISI within the same user has been avoided. The proposed scheme has been tested with 50 MHz, 100 MHz and 500 MHz sampling frequencies for 50 users, 25 users and 5 users respectively by using 2.5 GHz bandwidth. 8-bits of data was transmitted and detected for different users using Matlab and Simulink Models. The results were analyzed in perfect synchronization condition and compared between integrated window energy detector UWB receiver and an UWB receiver using a matched filter. The performances are evaluated on the basis of BER. To observe the impact of synchronization, both receivers were evaluated with some timing mismatch. It is concluded that the scheme works well for the lower sampling rate for both types of UWB receivers stated above. It can also be concluded by observing the results that the UWB receiver using matched filter has better performance in noisy environment compared to energy detector UWB receiver with integrated window. The performance of energy detector UWB receiver with integrated window and UWB receiver with matched filter were also evaluated with timing mismatch. It can be concluded that the UWB receiver with integrated window has better performance compared to UWB receiver using matched filter if the synchronization is not achieved properly. The UWB receiver with matched filter is more vulnerable against timing mismatch compared to UWB receiver with integrated window.QC 20120612
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Tan, Kaiser Beng Kiat. "Performance analysis of adaptive antenna with coding and rake receiver." Thesis, Monterey, California. Naval Postgraduate School, 2002. http://hdl.handle.net/10945/6012.
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Approved for public release; distribution is unlimitedIn this thesis, we presented the analytical expressions for probability of bit error (BER), the probability density function (PDF) and cumulative distribution function (CDF) of the output signal-to-noise-plus-interference ratio (SINR) of an adaptive antenna operating in multipath environments with multiple interferers and flat Rayleigh fading. The analytical expressions for BER, PDF and CDF were then developed including the effect of coding and the use of RAKE receiver. The performance of adaptive antenna with and without coding as well as with RAKE receiver was analyzed and compared.
13
Buxa, Peter E. "Parameterizable Channelized Wideband Digital Receiver for High Update Rate." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1183475958.
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Ugural, Suleyman Sadi. "Modeling and performance analysis of cellular CDMA Channel with rake receiver." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://edocs.nps.edu/npspubs/scholarly/theses/2001/Sep/01Sep_Ugural.pdf.
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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, September 2001.Thesis advisor(s): Ha, Tri T.; Tighe, Jan E. "Septembeer 2001". Includes bibliographical references (p. 77-78). Also available online.
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XU, BIN. "A Blind Space-Time Decorrelating RAKE Receiver in a DS-CDMA System in Multipath Channels." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1078193785.
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Zahid, Kazi. "Space-time Processsing for the Wideband-CDMA System." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/30783.
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Deployment of antenna arrays is a very promising solution to reduce the Multiple Access Interference (MAI) from high data rate users in the Wideband Code Division Multiple Access (W-CDMA) system. Combining the antenna array with a RAKE receiver, both of which exploits multipath diversity, can significantly improve the system performance. In this research, we investigate the performance of these beamformer-RAKE receivers, also known as two-dimensional (2-D) RAKE receiver, for the reverse link of the W-CDMA system. We consider three different Pilot Symbol Assisted (PSA) beamforming techniques, Direct Matrix Inversion (DMI), Least-Mean Square (LMS) and Recursive Least Square (RLS) adaptive algorithms. Two different Geometrically Based Single Bounce (GBSB) statistical channel models are considered, one, which is more suitable for array processing, and the other is conductive to RAKE combining. The performances of the 2-D RAKE receivers are evaluated in these two channel models as a function of the number of antenna elements and RAKE fingers. It is shown that, in both the cases, the 2-D RAKE receiver outperforms the conventional RAKE receiver and the conventional beamformer by a significant margin. Also, the output SINR expression of a 2-D RAKE receiver with the general optimum beamformer is derived.Master of Science
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Kim, Jina. "Area and Power Conscious Rake Receiver Design for Third Generation WCDMA Systems." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/30972.
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A rake receiver, which resolves multipath signals corrupted by a fading channel, is the most complex and power consuming block of a modem chip. Therefore, it is essential to design a rake receiver be efficient in hardware and power. We investigated a design of a rake receiver for the WCDMA (Wideband Code Division Multiple Access) system, which is a third generation wireless communication system. Our rake receiver design is targeted for mobile units, in which low-power consumption is highly important. We made judicious judgments throughout our design process to reduce the overall circuit complexity by trading with the performance. The reduction of the circuit complexity results in low power dissipation for our rake receiver. As the first step in the design of a rake receiver, we generated a software prototype in MATLAB. The prototype included a transmitter and a multipath Rayleigh fading channel, as well as a rake receiver with four fingers. Using the software prototype, we verified the functionality of all blocks of our rake receiver, estimated the performance in terms of bit error rate, and investigated trade-offs between hardware complexity and performance. After the verification and design trade-offs were completed, we manually developed a rake receiver at the RT (Register Transfer) level in VHDL. We proposed and incorporated several schemes in the RT level design to enhance the performance of our rake receiver. As the final step, the RT level design was synthesized to gate level circuits targeting TSMC 0.18 mm CMOS technology under the supply voltage of 1.8 V. We estimated the performance of our rake receiver in area and power dissipation. Our experimental results indicate that the total power dissipation for our rake receiver is 56 mW and the equivalent NAND2 circuit complexity is 983,482. We believe that the performance of our rake receiver is quite satisfactory.Master of Science
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Lane, Philip Mark. "Design and realisation strategies for very high bit-rate optical receivers." Thesis, Bangor University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303366.
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Choi, Seyeong. "Design and performance evaluation of RAKE finger management schemes in the soft handover region." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1489.
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Choi, Jung Han. "A Si Schottky diode demultiplexer circuit for high bit rate fiber optical receivers." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972764240.
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Hammerschmidt, Joachim S. "Adaptive space and space-time signal processing for high-rate mobile data receivers /." Düsseldorf : VDI-Verl, 2001. http://www.gbv.de/dms/bs/toc/329240056.pdf.
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Li, Sun, Wang Yinfeng, and Zhang Qishan. "AN ADAPTIVE SIGNAL SEARCH ALGORITHM IN GPS RECEIVER." International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/607349.
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International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, CaliforniaGPS signal fixed dwell and variable dwell time sequential search algorithms are compared with probability of false alarm and detection and searching rate. An adaptive search algorithm is proposed according to different work modes and interference or jam circumstance, which has effectively improved signal acquiring speed and reliability. Mathematical simulation shows its correction and feasible.
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McKinstry, David R. "Ultra-wideband Small Scale Channel Modeling and its Application to Receiver Design." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/33738.
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Recently, ultra-wideband (UWB) technology based on the transmission of short duration pulses has gained much interest for its application to wireless communications. This thesis covers a range of topics related to the analysis of indoor UWB channels for communications and to system level design issues for UWB receivers. Measurement based UWB small scale modeling and characterization efforts as well as UWB communications system analysis and simulation are presented.
Relevant background material related to UWB communications and wireless channel modeling is presented. The details of the small scale channel modeling work, including statistical characterization and potential models, are discussed. A detailed analysis of the CLEAN algorithm, which was used to process all the measurement data, is also given, and some limitations of the algorithm are presented.
The significance of the channel impulse response model chosen for the simulation of UWB communications systems is also evaluated. Three traditional models are found to be useful for modeling NLOS UWB channels, but not LOS channels. A new model for LOS UWB channels is presented and shown to represent LOS channels much more accurately than the traditional models.
Receiver architectures for UWB systems are also discussed. The performance of correlation receivers and energy detector receivers are compared as well as Rake diversity forms of each of these types to show tradeoffs in system complexity with performance. Interference to and by UWB signals is considered. A narrowband rejection system for UWB receivers is shown to offer significant system improvement is the presence of strong interferers.Master of Science
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Lillie, Andrew G. "Iterative receiver techniques for high data rate indoor wireless communication systems." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419135.
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Liang, Jifu. "A Low-Power Receiver for Simultaneous Electrocardiogram and Respiratory Rate Detection." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1467815115.
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Troublefield, Robert C. "DIGITAL RECEIVER PERFORMANCE." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606794.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaBit errors often occur in a wireless communications link when impairments alter the transmitted signal. It is advantageous to be able to predict how well a system will tolerate transmission problems. This paper details laboratory performance measurements and comparisons in terms of evaluating configurations of a digital receiver for Feher patented Quadrature Phase Shift Keying (FQPSK-B) demodulation. The transmitted signal is subjected to calibrated levels of impairments while the receiver performance is monitored in real-time.
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Dourbal, Paul, Yuriy Bouglo, Val Fleyshman, Robert Mayer, Jerry Okoro, and Boris Shikhalev. "High Data Rate ARTM Tier II Telemetry Waveforms Receiver Analysis and Design." International Foundation for Telemetering, 2010. http://hdl.handle.net/10150/604301.
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ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, CaliforniaIn this article we show how phase noise and demodulator complexity define the potential performance of high data rate telemetry receivers for ARTM continuous phase modulation (ARTM CPM) signals. Given a level of phase noise and demodulator complexity, we can predict the potential performance of a receiver. We also provide the results of actual receiver performance measurements (obtained using RCB-4000 Telemetry Receiver). We develop a simplified analytical model for an ARTM CPM signal transmission and present the resulting equation for phase increment difference between close signal sequences. The analysis of demodulator performance deterioration due to inter-symbol interference and due to receiver phase noise is then provided. Actual receiver phase noise data is included and is used to analyze demodulator performance.
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Varela, Julio, and Robert Conrad. "A COMMERCIAL OFF THE SHELF CONTINUOUSLY TUNABLE HIGH DATA RATE SATELLITE RECEIVER." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/608252.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaTSI TelSys, Inc. is in the process of developing a production level, continuously tunable satellite receiver designed to support multiple high data rate, low earth and geostationary orbit missions in the 20 Mbps to 800 Mbps composite QPSK data rate range. This paper will evaluate market demands on satellite receivers and outline receiver design technique as a solution to high rate, multi-mission support.
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Ghosh, Kaushik. "Downlink W-CDMA performance analysis and receiver implmentation on SC140 Motorola DSP." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969/169.
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Yang, Min. "A two-stage multi-path searcher for WCDMA RAKE receivers." Thesis, 2007. http://spectrum.library.concordia.ca/975464/1/MR34726.pdf.
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The performance of a Universal Mobile Telecommunication System (UMTS) base station RAKE receiver is largely dependent on the accuracy of the estimate of the time-delay of the different paths. A commonly employed technique in a RAKE receiver is to use a multi-path searcher (MPS) to find the number of different strong paths and the time-delay of these paths. The drawback of the existing MPS algorithms for UMTS base-station RAKE receiver is that their computational complexity is high or the probability of detection is low. The full search with full contribution MPS gives the best result in terms of the detection probability, but its complexity is high. To reduce the complexity, a full search with partial contribution MPS has been proposed, but the detection probability of this algorithm is low. In order to solve this problem, in this thesis, a two-stage MPS, based on a dual-dwell technique is proposed. In the proposed algorithm, all the delay offsets in the search window are first evaluated for possible true paths by using only part of the slots in the correlation period. This helps to quickly narrow down the number of search candidates with only a small amount of computation needed. Then, in the second stage, the M strongest candidates from the first stage are further evaluated by using all the slots in the correlation period. The simulation results show that the proposed algorithm has a detection performance very close to that of the conventional full search with full contribution MPS, while at the same time it has a substantially lower computational complexity
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Ke, Chih-chiang, and 柯智強. "Cost-Based CLEAN Algorithm for Selective RAKE Receivers in UWB Systems." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/g29pht.
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碩士國立中山大學
電機工程學系研究所
96
In this thesis, we propose a cost-based CLEAN algorithm to accurately find dense multi-path parameters and improve the performance of selective RAKE receiver in indoor UWB systems. RAKE receiver can resolve the dense multi-path interference problems with the multi-path parameters. Because the weak paths are of lower valuable for system performance improvement, selective RAKE receiver combines only the strongest multi-path components and reduce the number of fingers to lower the complexity of RAKE receiver. However, selective RAKE receiver needs accurate multi-path detection to decide the suitable number and parameters of fingers. In order to improve the performance of selective RAKE receiver, the main issue in this thesis is to detect the best paths of channel with the CLEAN algorithm. CLEAN algorithm uses the correlation of the received signal and the template signal as the basis for searching paths. If there are closely adjacent paths, or if one of signal paths is relatively stronger, the detection error of paths may occur and thus affects the performance of the receiver. EP-based CLEAN algorithm uses the cost function and the evolutionary programming (EP) to search the multi-path delay times and gain coefficients for minimizing the cost function. Accurate multi-path detection and high resolution of adjacent paths can be obtained. However, EP-based CLEAN algorithm makes a time-consuming blind search. In the thesis, a CLEAN algorithm based on the cost function is proposed. The proposed cost-based CLEAN algorithm searches the delay times near the peaks of the cross-correlation for local minimum of the cost function, and then uses CLEAN algorithm to extract autocorrelation components and obtain the accurate multi-path detection. By testing the IEEE802.15.3a UWB channel models, and comparing with CLEAN algorithm, the cost-based CLEAN algorithm in the thesis can achieve better detection accuracy in multi-path searching, and improve the performance of selective RAKE receiver.
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Chi, hsin-hsu, and 紀信旭. "Rake Receivers Using RLS-like Adaptive Filtering for 3GPP WCDMA-FDD Uplink." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/75217878592833950844.
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碩士國立中央大學
通訊工程研究所
90
In the future, mobile communications do not only provide one kind of service. They provide many kinds of service such as voice, video, data …etc. In order to provide variable service, it must to develop new technology can provide better quality. In this paper, we present a smart antenna adaptive processing structure for the 2-D RAKE receiver design built on top of the current existent 1-D RAKE receiver. This method can be applied to the 3GPP WCDMA communication systems. In this paper, we use the RLS-like (Recursive Lease Square-like) adaptive filter algorithm and the MRC (Maximum Ratio Combining) method to achieve the concept of 2-D RAKE processing structure. The processing structure can be used to combat the “Near-Far” problem and offer the “Interference-Resistant” property. By adopting this method, we can obtain the following advantages: 1. To decrease the transmit power to reduce mutual interference between users. 2. To increase the system capacity and coverage.
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Yang, Siang-Yu, and 楊翔宇. "Performance Comparison of Selective Rake Receivers with CLEAN Algorithms in UWB Systems." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/93950824827937233232.
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碩士國立中山大學
電機工程學系研究所
94
The Ultra-Wideband (UWB) channel is a dense multipath channel. The system performance and design complexity issues of selective-Rake receiver (SRake) are studied. Rake receiver has difficulties achieving desired system performance in the dense multipath environment. The main ideas of SRake receiver are to obtain the SNR level on known multipath channel and determine the desired number of Rake fingers. In the implementation of the SRake, the CLEAN algorithm is used in selecting the paths with relatively high energy. We can improve the performance of SRake receiver by increasing the accuracy of path selection. By the property of local maximum peak within the smaller partition, Two-Stage CLEAN algorithm acquires the more accurate delay time of multipath. In order to mitigate the sidelobe effect and noise interference, the key assumption in the Deng’s Modified CLEAN algorithm is that using average amplitude around the considered data change as the criterion to determine if the data value is a true path. In this thesis, we investigate CLEAN, Two-Stage CLEAN and Deng’s Modified CLEAN algorithm in three different systems including UWB-Impulse Radio, Pulse Radar and DS-UWB. From the performance comparison, it can be seen that the Two-Stage CLEAN algorithm that has the highest accuracy of path selection in UWB system.
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Jiang, You-Min, and 江佑民. "Performance Analysis of RAKE Receivers for cdma2000 Uplink in Band-limited Rayleigh Fading Channels." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/60997558642195041331.
Full textAbstract:
碩士國立交通大學
電信工程系
89
The purpose of this thesis is to analyze the performance of Rake receivers for cdma2000 reverse link. The transmitted signal consists of multiple orthogonal signals, each coded with a distinct Walsh code. The pilot channel is used for initial acquisition, code/timing tracking, RAKE-receiver coherent reference recovery, and power control measurements. In addition, Hybrid Phase Shift Keying (HPSK) modulation scheme is proposed as the spreading technique to minimize the zero-crossing signal transition and obtains higher power efficiency. We consider frequency selective Rayleigh slowly fading channels. The receiver uses a second-order Butterworth low-pass filter to estimate the fading amplitude and the phase shift. Each finger has its own tracking loop and channel estimator. Both maximal ratio combining and equal gain combining rules are investigated. Our analysis takes into account the channel estimation error, the self-interference (intersymbol and inter-channel interference), multiple access interference (MAI) and the band-limiting effect. Numerical bit error rate (BER) performance of the RAKE receiver using MRC and EGC are obtained by both computer simulations and analytical formulae. As expected, MRC yields better performance and ISI and MAI are the primary limiting factors even if perfect channel estimate is available.
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Yi-WeiLu and 盧奕維. "Performance Analyses on Rake Receivers with Multipath Interference Cancellation over Orthogonal and Cyclic MIMO-CDMA." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/03620254877132112769.
Full textAbstract:
碩士國立成功大學
電腦與通信工程研究所
98
In the 3rd generation mobile communication system, as a result of Multiple Access Interference (MAI) caused by multi-users and inter-symbol interference (ISI) due to multipath propagation delay, those interferences limit the capacity of multiple users in the cellular system and affect the transmission quality of communication, decreasing the system performance seriously. Besides, the orthogonal condition of spreading sequences in MIMO-CDMA system is destroyed and cause interference in multipath environment and non-quasi static channel. So as to decrease the complexity of system and overcome the multipath fading, the parallel rake receivers to despread orthogonal- and cyclic- inherent space-time code and multipath interference cancellation to enhance the signal signature are proposed in this thesis. The system design is a combination of our proposed decoding structure and using the correlation characteristic of M-sequence to separate multipath signals caused by spatial diversity in MIMO system. To overcome the time dispersion of the transmitted signal due to multipath effect, we utilize rake receivers with time diversity and achieve the maximal diversity gain from the independent multipath component. After that, we use the proposed multipath interference mechanism to reconstruct the several replicas of the same information signal which is transmitted over transmit antennas, eliminating the ISI before maximum ratio combining. We analyze the different transmission rate and diversity order for different transmit antennas. Furthermore, the exact error probability of the proposed scheme is also derived. Mathematical analysis and simulation results show that the proposed scheme in multipath environment over non-quasi static channel, it can be decoded by a significant low complexity ML decoder. Comparing to conventional STBC with single rake receiver in MIMO-CDMA scheme, it obtains the better system performance and suitable to use in the wireless mobile communication.
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"Novel self-decorrelation and fractional self-decorrelation pre-processing techniques to enhance the output SINR of single-user-type DS-CDMA detectors in blind space-time RAKE receivers." 2002. http://library.cuhk.edu.hk/record=b5891142.
Full textAbstract:
Cheung Shun Keung.Thesis (M.Phil.)--Chinese University of Hong Kong, 2002.
Includes bibliographical references (leaves 80-83).
Abstracts in English and Chinese.
Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- The Problem --- p.1
Chapter 1.2 --- Overview of CDMA --- p.2
Chapter 1.3 --- Problems Encountered in Direct-Sequence (DS)CDMA --- p.3
Chapter 1.3.1 --- Multipath Fading Scenario in DS-CDMA Cellular Mo- bile Communication --- p.3
Chapter 1.3.2 --- Near-Far Problem --- p.4
Chapter 1.4 --- Delimitation and Significance of the Thesis --- p.5
Chapter 1.5 --- Summary --- p.7
Chapter 1.6 --- Scope of the Thesis --- p.8
Chapter 2 --- Literature Review of Blind Space-Time Processing in a wire- less CDMA Receiver --- p.9
Chapter 2.1 --- General Background Information --- p.9
Chapter 2.1.1 --- Time Model of K-User Chip-Synchronous CDMA --- p.9
Chapter 2.1.2 --- Dispersive Channel Modelling --- p.10
Chapter 2.1.3 --- Combination of K-user CDMA Time Model with the Slow Frequency-Selective Fading Channel Model to form a completed Chip-Synchronous CDMA Time Model --- p.13
Chapter 2.1.4 --- Spatial Channel Model with Antenna Array [9] --- p.15
Chapter 2.1.5 --- Joint Space-Time Channel Model in Chip-Synchronous CDMA --- p.19
Chapter 2.1.6 --- Challenges to Blind Space-Time Processing in a base- station CDMA Receiver --- p.23
Chapter 2.2 --- Literature Review of Single-User-Type Detectors used in Blind Space-Time DS-CDMA RAKE Receivers --- p.25
Chapter 2.2.1 --- A Common Problem among the Signal Processing Schemes --- p.28
Chapter 3 --- "Novel ""Self-Decorrelation"" Technique" --- p.29
Chapter 3.1 --- "Problem with ""Blind"" Space-Time RAKE Processing Using Single- User-Type Detectors" --- p.29
Chapter 3.2 --- "Review of Zoltowski & Ramos[10,11,12] Maximum-SINR Single- User-Type CDMA Blind RAKE Receiver Schemes" --- p.31
Chapter 3.2.1 --- Space-Time Data Model --- p.31
Chapter 3.2.2 --- The Blind Element-Space-Only (ESO) RAKE Receiver with Self-Decorrelation Pre-processing Applied --- p.32
Chapter 3.3 --- Physical Meaning of Self-Decorrelation Pre-processing --- p.35
Chapter 3.4 --- Simulation Results --- p.38
Chapter 4 --- """Fractional Self-Decorrelation"" Pre-processing" --- p.45
Chapter 4.1 --- The Blind Maximum-SINR RAKE Receivers in Chen et. al.[l] and Wong et. al.[2] --- p.45
Chapter 4.2 --- Fractional Self-Decorrelation Pre-processing --- p.47
Chapter 4.3 --- The Blind Element-Space-Only (ESO) RAKE Receiver with Fractional Self-Decorrelation Pre-processing Applied --- p.50
Chapter 4.4 --- Physical Meaning of Fractional Self-Decorrelation Pre-processing --- p.54
Chapter 4.5 --- Simulation Results --- p.55
Chapter 5 --- Complexity Analysis and Schematics of Proposed Techniques --- p.64
Chapter 5.1 --- Computational Complexity --- p.64
Chapter 5.1.1 --- Self-Decorrelation Applied in Element-Space-Only (ESO) RAKE Receiver --- p.64
Chapter 5.1.2 --- Fractional Self-Decorrelation Applied in Element-Space- Only (ESO) RAKE Receiver --- p.67
Chapter 5.2 --- Schematics of the Two Proposed Techniques --- p.69
Chapter 6 --- Summary and Conclusion --- p.74
Chapter 6.1 --- Summary of the Thesis --- p.74
Chapter 6.1.1 --- The Self-Decorrelation Pre-processing Technique --- p.75
Chapter 6.1.2 --- The Fractional Self-Decorrelation Pre-processing Tech- nique --- p.76
Chapter 6.2 --- Conclusion --- p.78
Chapter 6.3 --- Future Work --- p.78
Bibliography --- p.80
Chapter A --- Generalized Eigenvalue Problem --- p.84
Chapter A.1 --- Standard Eigenvalue Problem --- p.84
Chapter A.2 --- Generalized Eigenvalue Problem --- p.84
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Huang, Ten-Kuon, and 黃德岡. "CMOE-initialized CMRLS RAKE Receiver." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/56316313024747700478.
Full textAbstract:
碩士國立臺灣海洋大學
電機工程學系
92
Abstract Conventional RAKE receiver exploits the diversity technique to gather signal energies at different delays to improve the signal to interference plus noise ratio (SINR), but its performance is poor. The bit error rate (BER) performance of constant modulus algorithm RAKE (CMA RAKE) receiver is shown to be better than that of the decorrelating RAKE (D-RAKE) receiver. However, the CMA RAKE receiver is susceptible to misconvergence in the fading channel environment due to its multimodal cost surface. In this paper, we propose a RAKE receiver with an initialization scheme for the CMA RAKE receiver by using the solution form the minimization of the constrained minimum output energy (CMOE) criterion, and which combined with constant modulus recursive least square (CMRLS) algorithm called CMOE-initialized CMRLS RAKE receiver. The RAKE receiver we proposed owns faster convergence speed and better BER performance, furthermore it is not susceptible to misconvergence. Simulations confirm the CMOE-initialized CMRLS RAKE receiver we proposed is superiority over the CMA RAKE receiver in terms of the performance of SINR and BER. Keyword：CMA、CMOE、RAKE Receivers.
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Hsieh, Weii, and 謝瑋一. "Adaptive LMMSE Rake Receiver in WCDMA." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/90115252087328850865.
Full textAbstract:
碩士國立交通大學
電子工程系
88
This thesis proposes a modified adaptive LMMSE algorithm to significantly improve the performance of the rake receiver in the case of high data rate situation, while reducing computational complexity, compared with conventional approach. The modified LMMSE algorithms also lead to a more stable convergence performance. The thesis also extensively studies the rake receiver, which is an important component in the third Generation Mobile Communication (Wideband Code Division Multiple Access) systems.
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Lay, Rong-Horng, and 賴榮宏. "CMA-RAKE Receiver for CDMA Systems." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/50624929438805639244.
Full text
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Chang, Jen-Tang, and 張忍堂. "An FFT-based DPSK RAKE Receiver." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/93108286074210693274.
Full textAbstract:
碩士國立交通大學
電信工程系
88
This thesis describes a new RAKE receiver architecture and a new timing correction method of spreading code. Unlike general RAKE receiver that processes signals in time domain, this new RAKE receiver will use Fast Fourier transform (FFT) to process signals in frequency domain. The modulation scheme used by the system is differential phase shift keying (DPSK), so transmitter does not need to transmit extra pilot signal or pilot symbol for channel sounding. Receiver can obtain information data from its modulation characteristic directly or can estimate the channel impulse response to make decision of DPSK signal and then use differential decoding method to obtain information data. In order to improve system performance, this new RAKE receiver also adopts decision-directed method for channel estimation. About correcting the timing of spreading code, we assume the channel is a minimum phase system and take advantage of the characteristic of FFT to recover the timing of spreading code. Monte Carlo simulation is used to evaluate the performance of our RAKE receiver and the timing correction method. Simulation results can show that this new RAKE receiver and timing correction method will work well in both a static channel and a mobile radio channel.
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Θώμος, Χρήστος. "Δέκτες/αποδιαμορφωτές βασικής ζώνης για ασύρματα συστήματα υπερ-ευρείας ζώνης (ultra wideband)." Thesis, 2011. http://hdl.handle.net/10889/5864.
Full textAbstract:
Η υλοποίηση πρακτικών ασύρματων συστημάτων επικοινωνίας δεδομένων στην τεχνολογία UWB παρουσιάζει ιδιαίτερες προκλήσεις, κυρίως λόγω της χαμηλής ισχύος εκπομπής και της πολύ σύντομης διάρκειας των παλμών που χρησιμοποιούνται, οι οποίοι θα πρέπει να στέλνονται με πολύ μεγάλες ταχύτητες για την επίτευξη των επιθυμητών ρυθμών μετάδοσης. Το κανάλι μετάδοσης είναι ιδιαίτερα επιλεκτικό ως προς την συχνότητα και εξαιρετικά πυκνό και πλούσιο σε πολυοδικές συνιστώσες με αρκετά μεγάλες καθυστερήσεις. Αυτές οι συνιστώσες μπορούν να ανιχνευθούν και να συλλεχθούν χρησιμοποιώντας κατάλληλες δομές δεκτών RAKE, οι οποίοι τις συνθέτουν ώστε να μεγιστοποιηθεί η ενέργεια του ωφέλιμου σήματος, αυξάνοντας την απόδοση του συστήματος. Οι δομές αυτές παρουσιάζουν την καλύτερη απόδοση σε τέτοια συστήματα, αλλά έχουν μεγάλη υπολογιστική πολυπλοκότητα, καθώς για την ικανοποιητική απόδοση του συστήματος πρέπει να συνδυάσουν πολλές συνιστώσες, δεδομένης και της χαμηλής ισχύος εκπομπής της τεχνολογίας. Συνεπώς, για την υλοποίηση ενός πρακτικού και αποδοτικού συστήματος, σημαντικό ζήτημα αποτελεί ο τρόπος επιλογής και συνδυασμού των συνιστωσών μέσω ενός αλγορίθμου που θα χρησιμοποιεί τον μικρότερο δυνατό αριθμό δακτύλων.
Στόχοι της διατριβής ήταν η μελέτη της τεχνολογίας UWB, η διερεύνηση των παραμέτρων των παλμικών UWB συστημάτων, η μελέτη και εξομοίωση μοντέλων του καναλιού, η κατανόηση των οποίων είναι απαραίτητη για την αποτελεσματική ανίχνευση του σήματος και τον σχεδιασμό των αλγορίθμων ψηφιακής επεξεργασίας του σήματος, η διερεύνηση δεκτών RAKE καθώς και εναλλακτικών δομών, οι εξομοιώσεις πομποδέκτη παλμικού UWB σε επίπεδο συστήματος με έμφαση στον RAKE και τον εκτιμητή καναλιού, η διερεύνηση παραμέτρων και τεχνικών για την υλοποίηση σε υλικό και τέλος η ανάπτυξη, ο σχεδιασμός και υλοποίηση μιας πρακτικής δομής δέκτη με RAKE αποδιαμορφωτή και εκτιμητή καναλιού που συνδυάζει χαμηλή πολυπλοκότητα και ικανοποιητική απόδοση. Παρουσιάζονται και συγκρίνονται τρεις νέες διαφορετικές προσεγγίσεις σχεδίασης, οι οποίες βασίζονται σε προτεινόμενο υβριδικό αλγόριθμο (HPS) για την μείωση της πολυπλοκότητας του RAKE και δίνονται αποτελέσματα που αφορούν στην αξιοποίηση του υλικού και στις επιδόσεις του συστήματος. Tα αποτελέσματα παρουσιάζουν το trade-off ανάμεσα στην συλλογή ενέργειας, την απόδοση του δέκτη και την πολυπλοκότητά του. Η αποτελεσματικότητα των προτεινόμενων αρχιτεκτονικών επαληθεύεται μέσω ειδικής πλατφόρμας αναδιατασσόμενου υλικού στην οποία υλοποιήθηκε η σχεδίαση.Τhe implementation of practical wireless data communications systems for the UWB technology is very challenging due to the use of low-power ns-duration pulses which have to be sent in a high-frequency in order to achieve the desirable data rates. The UWB channel is highly frequency selective and it is characterized by dense and rich multipath propagation and large multipath delay spreads in some cases. A RAKE receiver can be employed in order to exploit multipath diversity and effectively capture the desired signal energy which is dispersed over the various multipath components, helping to mitigate fading. However, the particular nature of UWB results in very low-energy paths which, in conjunction with high multipath diversity, leads to a RAKE receiver that must exploit a large number of MPCs in order to optimize the received SNR. Thus, for the implementation of a low-complexity system it is important to define a novel method for the selection and combining of MPCs and develop an algorithm that is able to utilize a minimum number of fingers in the RAKE structure. Our work was focused in the study of UWB technology, the investigation of the parameters of IR-UWB systems, the study and understanding of the channel models which is necessary for the design of practical and efficient DSP algorithms, the investigation of RAKE type receivers as well as other alternative structures, the system-level simulations of the IR-UWB transceiver with emphasis given to the algorithms for the RAKE demodulator and channel estimator, the investigation of the parameters and techniques for the implementation of the system in hardware and finally, the development, design, and implementation of a practical receiver structure that includes a RAKE demodulator and a channel estimator and combines low complexity and satisfactory performance. The ultimate goal of this work is the presentation and investigation of the proposed channel estimator and (MRC)-RAKE receiver architecture which is based on a proposed novel hybrid algorithm called HPS. Three different design approaches aiming to a practical system implementation in an FPGA are proposed and compared and system/algorithm performance, hardware utilization results are provided. The obtained results demonstrate the trade-off between energy capture, performance and receiver complexity. The effectiveness of the proposed architectures is verified on a special FPGA platform which was used for the implementation of the receiver structure.
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Lin, Jian-Hong, and 林建宏. "A Generalized RAKE Receiver for Wireless Communications." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/03454898829178818181.
Full textAbstract:
碩士國立臺灣海洋大學
電機工程學系
96
As mobile communication systems continue to spread, code-division multiple access (CDMA) has become the mainstream of wireless communications. Under the demand of high speed transmission and low bit error rate, the RAKE receiver for combating channel fading has been widely used in CDMA mobile devices. Conventional RAKE receiver combines each resolved path signal in different time slots to generate a decision statistic with higher signal-to-noise ratio for improving detection capability. Based on the same structure, generalized RAKE (G-RAKE) receiver can suppress multiuser interference (MUI), intersymbol interference (ISI) and noise to yield even lower bit error rate. In this thesis, we propose a modified version of G-RAKE receiver which allows each user to use its user-specific orthogonal spreading code (independent of symbols) in more practical situations. We also provide statistical analysis and computer simulations to verify the effectiveness of the proposed method.
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Shih-tsang, Tang, and 湯士滄. "Channel estimation of RAKE receiver using fuzzy theory." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/38808428248000879676.
Full textAbstract:
碩士國立海洋大學
航海技術學系
83
This thesis presents and discusses the fuzzy RAKE receiver for Multipath fading channels. ANFIS (Adaptive Network Fuzzy Inference System) is employed to estimate the channel characteristics for the RAKE receiver. We improve the speed of convergence of ANFIS in the training phase by the parallel self- organizing membership functions. Using ANFIS to combine the multipath signals is modeled and some numerical results are presented. It is shown that the proposed system outperforms the traditional Digital-RAKE and approximates to the ideal- RAKE.
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Li, Chun-Cheng, and 李君政. "CMRLS RAKE Receiver with Space Diversity and AIC." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/49062583578385073230.
Full textAbstract:
碩士國立臺灣海洋大學
電機工程學系
94
Abstract Although conventional RAKE receiver can compensate for multi-path fading, but multiple-access interference (MAI) was not considered in this scheme. When users of the system increasing, the performance of system which used RAKE receiver will decay. In order to overcome the problem of multiple-access interference, we use an adaptive interference canceller(AIC) which compose of a code-orthogonalizing filter(COF) and a differential detector(DD).To improve the quality of received signal, we combine maximal ratio combining(MRC).Above-mentioned adaptive RAKE receiver can support high data rate without bandwidth expansion and overcome MAI, but training sequences and convergence speed is its fault. In this paper, we propose a constant modulus recursive least square(CMRLS) RAKE receiver which combined with constant modulus recursive least square algorithm. So we called CMRLS RAKE with space diversity and adaptive interference cancellation. Under multiple path fading, we compared a RAKE receiver which we proposed and conventional RAKE receiver. We found that former not only own the advantage of blind filtering technique and faster convergence speed, but also improve system performance in BER. Simulations confirm the RAKE receiver which we proposed is superiority over the conventional RAKE receiver in terms of the performance of SINR and BER. Keyword：Multiple Access Interference、Adaptive Interference Canceller、Adaptive RAKE Receivers.
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Lee, Jih-Shin, and 李日新. "CMRLS-RAKE Receiver for Low Spreading Gain Systems." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/18948031929815542399.
Full textAbstract:
碩士國立海洋大學
電機工程學系
91
The development of the WCDMA tends to increase the data rate without bandwidth expansion by reducing the spreading gain. One of the solutions is to reduce the spreading gain, but the small spreading gain will cause interpath interfereence (IPI) due to imperfect autocorrelations of spreading sequence in multipath channels. The RAKE receivers which combined with constrained minimum mean square error (CMMSE) algorithm can support high data rate without bandwidth expansion and overcome IPI effectively, but training sequences and convergence speed is its fault. In order to improve these faults, we propose a RAKE receiver which combined with constant modulus recursive least square (CMRLS) called CMRLS- RAKE receiver. Under low spreading condition, comparing CMRLS- RAKE receiver and CMMSE-RAKE receiver. We found that former not only own the advantage of blind filtering technique and faster convergence speed, but also improve system performance in BER about ~ . According to those mention above, the CMRLS-RAKE receivers are more effectively and faster overcome IPI than the CMMSE-RAKE receivers.
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Pai, Chia-Wei, and 白嘉煒. "Parameter Estimation of RAKE Receiver Using the EM Algoritm." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/30804610925140418226.
Full textAbstract:
碩士國立海洋大學
航運技術研究所
87
We employ the RAKE receiver with EM (expectation-maximization) algorithm to solve the problems of multipath propagation and fading. The key issue is to decompose the observed data into their channel components, then to estimate the unknown parameters of each channel separately. Using the maximal ratio combiner, the estimated parameters are applied to the RAKE receiver to improve the performance. EM algorithm produces maximum-likelihood estimates of parameters when there is a many-to-one mapping from an underlying distribution to the distribution governing the observed data. With the property of convergence, the algorithm is iterated with increasing likelihood. As a result, the proposed RAKE receiver has a better performance than the traditional one in terms of BER.
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Hong, Mu-Tseng, and 洪牧村. "Direct Sequence Spread Spectrum RAKE Receiver for Wireless Communication." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/29944557861712288502.
Full textAbstract:
碩士國立交通大學
電信研究所
82
Because of the presence of multipath fading, conventional narrowband signalings often suffer from severe performance degradation in a wireless communication environment. Wideband signaling is an alternative to mitigate fading if appropriate receiver design is in place, i.e, a RAKE-like receiver can be used to combine signals from distinct paths and provide much enhanced capability in a frequency-selective channel. On the other hand, RAKE receivers have been shown to achieve near optimal performance in slow frequency selective environments. This thesis concerned about the design of a RAKE-like direct sequence spread spectrum (DS/SS) receiver for wireless communication. Two receiver structures are discussed. The first one is the conventional RAKE structure which requires additional channel estimation and code acquisition circuits to combine different paths. The second alternative is realized by an adaptive filter which performs path combining, channel equalization and, to certain extent, code acquisition at the same time. We discuss issues related to the design of such systems like PN-code-acquisition probability, the relation between code acquisition and equalization, and bit error rate performance comparisons.
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Wang, Chih-Kai, and 王志凱. "Wireless Receivers using Minimum Bit-Error-Rate Criterion." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/58645730282399437538.
Full textAbstract:
碩士國立臺灣大學
電信工程學研究所
94
MBER criterion was discovered that it can adjust the weight of the linear receivers more intelligently than the traditional MMSE approach to achieve the small Bit-Error-Rate. This thesis not only research on MBER criterion and the optimization method of the cost function for MBER criterion(involve in nonlinear programming), but also take effort on designing the adaptive algorithm for it. Moreover, we develop an uplink power control method which can decrease the uplink power than the traditional method by exploiting the property of low BER for MBER criterion. On the back of last few chapters(ch3~ch5)，we verify that our methods has better performance than the traditional ones by showing the simulation results, and discuss how this happened.
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Yang, Tien-Hung. "An Equalized-RAKE Receiver for DS-CDMA Based UWB System." 2004. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2307200404180100.
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Wu, Yung-Tsung, and 吳永聰. "A Fuzzy RAKE Receiver Design with Applications to Underwater Communications." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/14448142849118731600.
Full textAbstract:
碩士國立海洋大學
航運技術研究所
85
AbstractFuzzy RAKE receiver schemes are presented in the environments of underwater acoustic multipath communications. There are severe multipath interference effects due to reflection and refraction. We take advantage of the RAKE schemes to separate different elements from multipath interference signals, then use fuzzy systems to combine different branch signals to make decisions for the adaptive and robust communication techniques. The RAKE schemes can aggregate different path signals to increase the decision reliability of the communication systems. Spread spectrum signals are used for combating or suppressing the detrimental effects of interference due to jamming, interference arising from other user of the channel, and self-interference due to multipath propagation. The fuzzy systems are robust and they can be employed to the nonlinear, time-variant and model-unknown system environments. The adaptive networks have learning ability, they can automatically tune the system parameters by means of adaptive algorithms with training data. In this thesis, we combine these advantages described previously to make up an adaptive and robust communication system in the presence of the multipath fading channel environments. It is shown that the fuzzy RAKE receivers are able to deal with the multipath interference signals with performances closely track the optimum BER (Bit Error Rate) obtained when the channel coefficients are known exactly.