Dissertations / Theses on the topic 'Beamforming'
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Sullivan, Arthur, Christos Christodoulou, and Charles W. Chandler. "NEXT GENERATION DIGITAL BEAMFORMING ARRAY OPTIMIZED BY NEURAL NETWORK BEAMFORMING TECHNIQUES." International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/607379.
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International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, CaliforniaThe next generation Digital Beamforming Array (DBFA) requires techniques beyond the existing adaptive processing and optimization approaches. By utilizing neural network processing and genetic algorithms that mimic complicated natural processes, such as the brain and natural selection, new and superior Antenna Arrays can be designed. The use of Neural Networks and Genetic Algorithms combined with the existing techniques for DBFAs can yield the ultimate in “real-time,” “smart” antenna performance. Cost is significantly reduced by; allowing large manufacturing tolerances, the use of inexpensive components, and correcting by neural network techniques. This paper describes the technology and proposes a practical application of the technique to design a DBFA to track and transmit/receive telemetry from a shipboard vertically launched medium range missile.
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Patil, Darshan. "Block Diagonalization Based Beamforming." Thesis, KTH, Teknisk informationsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-220403.
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With increasing mobile penetration multi-user multi-antenna wireless communication systems are needed. This is to ensure higher per-user data rates along with higher system capacities by exploiting the excess degree of freedom due to additional antennas at the receiver with spatial multiplexing. The rising popularity of "Gigabit-LTE" and "Massive-MIMO" or "FD-MIMO" is an illustration of this demand for high data rates, especially in the forward link. In this thesis we study the MU-MIMO communication setup and attempt to solve the problem of system sumrate maximization in the downlink data transmission (also known as forward link) under a limited availability of transmit power at the base station. Contrast to uplink, in the downlink, every user in the system is required to perform interference cancellation due to signals intended to other co-users. As the mobile terminals have strict restrictions on power availability and physical dimensions, processing capabilities are extremely narrow (relative to the base station). Therefore, we study the solutions from literature in which most of the interference cancellation can also be performed by the base station (precoding). While doing so we maximize the sumrate and also consider the restrictions on the total transmit power available at the base station. In this thesis, we also study and evaluate different conventional linear precoding schemes and how they relate to the optimal structure of the solution which maximize the effective Signal to Noise Ratio (SINR) at every receiver output. We also study one of the suboptimal precoding solutions known as Block-diagonalization (BD) applicable in the case where a receiver has multiple receive antennas and compare their performance. Finally, we notice that in spite of the promising results in terms of system sumrate performance, they are not deployed in practice. The reason for this is that classic BD schemes are computationally heavy. In this thesis we attempt to reduce the complexity of the BD schemes by exploiting the principle of coherence and using perturbation theory. We make use of OFDM technology and efficient linear algebra methods to update the beamforming weights in a smart way rather than entirely computing them again such that the overall complexity of the BD technique is reduced by at least an order of magnitude. The results are simulated using the exponential correlation channel model and the LTE 3D spatial channel model which is standardized by 3GPP. The simulated environment consists of single cell MU-MIMO in a standardized urban macro environment with up to 100 transmit antennas at the BS and 2 receive antennas per user. We observe that with the increase in spatial correlations and in high SNR regions, BD outperforms other precoding schemes discussed in this thesis and the developed low complex BD precoding solution can be considered as an alternative in a more general framework with multiple antennas at the receiver.För att klara det ökade mobilanvändandet krävs trådlösa kommunikationssystemmed multipla antenner. Detta, för att kunna garantera högre datatakt peranvändare och högre systemkapacitet, genom att utnyttja att extra antennerpå basstationen ger extra frihetsgrader som kan nyttjas för spatiell multiplexing.Den ökande populariteten hos “Gigabit-LTE”, “Massive-MIMO” och “FDMIMO”illustrerar detta behov av höga datatakter, framför allt i framåtlänken.I denna avhandling studerar vi MU-MIMO-kommunikation och försöker lösaproblemet att maximera summadatatakten i nedlänkskommunikation (ävenkallat framåtlänken), med begränsad tillgänglig sändeffekt hos basstationen.In nedlänken, till skillnad från upplänken, så måste varje användare hanterainterferens från signaler som är avsedda för andra mottagare. Eftersom mobilterminalerär begränsade i storlek och batteristyrka, så har de små möjligheteratt utföra sådan signalbehandling (jämfört med basstationen). Därför studerarvi lösningar från litteraturen där det mesta av interferensundertryckningenockså kan utföras vid basstationen (förkodning). Detta görs för att maximerasummadatatakten och även ta hänsyn till begränsningar i basstationens totalasändeffekt.I denna avhandling studerar vi även olika konventionella linjära förkodningsmetoderoch utvärderar hur de relaterar till den optimala strukturen hos lösningensom maximerar signal till brus-förhållandet (SINR) hos varje mottagare.Vi studerar även en suboptimal förkodningslösning kallad blockdiagonalisering(BD) som är användbar när en mottagare har multipla mottagarantenner, ochjämför dess prestanda.Slutligen noterar vi att dessa förkodningsmetoder inte har implementeratsi praktiska system, trots deras lovande prestanda. Anledningen är att klassiskaBD-metoder är beräkningskrävande. I denna avhandling försöker vi minskaberäkningskomplexiteten genom att utnyttja kanalens koherens och användaperturbationsteori. Vi utnyttjar OFDM-teknologi och effektiva metoder i linjäralgebra för att uppdatera förkodarna på ett intelligent sätt istället för att beräknadem på nytt, så att den totala komplexiteten för BD-tekniken reducerasåtminstone en storleksordning.Resultaten simuleras med både en kanalmodell baserad på exponentiell korrelationoch med den spatiella LTE 3D-kanalmodellen som är standardiseradav 3GPP. Simuleringsmiljön består av en ensam makrocell i en standardiseradstadsmiljö med MU-MIMO med upp till 100 sändantenner vid basstationenoch 2 mottagarantenner per användare. Vi observerar att BD utklassar övrigaförkodningsmetoder som diskuteras i avhandlingen när spatiella korrelationenökar och för höga SNR, och att den föreslagna lågkomplexa BD-förkodaren kanvara ett alternativ i ett mer generellt scenario med multipla antenner hos mottagarna.
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Tshangini, Mati. "Multicell robust downlink beamforming." Thesis, King's College London (University of London), 2016. https://kclpure.kcl.ac.uk/portal/en/theses/multicell-robust-downlink-beamforming(fde2310c-98de-440c-ab32-6a4257489d8c).html.
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The growth in large number of users and data exchange in cellular networks, has led to an urgent improvement of the power efficiency in cellular networks. The capacity and coverage are of main concern due to the fast growing applications and demand in different areas of use. The scarcity of the traditional communications resources like time and spectrum and the safety limits on transmit power from the base stations antennas as well as the mobile terminals demand the use of new additional resources such as spatial dimensions and cooperation for the realisation of the future cellular networks. Different distributively overlaid wireless cellular network systems are being deployed to meet demand for high data rates. However, these distributively overlaid wireless cellular networks can cause higher inter-cell interference if the signals from the source antennas are not combined and coordinated. Therefore, the solution to eliminating interference is considered as the benchmark for reducing the power consumption in the network. This thesis aims to address these concerns by proposing different algorithm techniques based on beamforming for Multi-Cell Processing (MCP) addressed across multiple coordinating multi-antenna base stations. First, a distributed optimization problem in a standard semidefinite relaxation (SDR) is introduced that minimizes a combination of the sum-power, used by each base station (BS) to transmit data to its local users, and the worst-case of the resulting overall interference induced on the other users of the adjacent cells in the presence of imperfect channel state information (CSI). The aim is to ensure that the worst-cases of the signal-to-interference- plus-noise ratio (SINR) at each user remains above the required level. The feasibility solutions are achieved for certain sets of SINRs only due to relaxation of optimal beamforming. To avoid relaxation and achieve higher SINRS, a second-order cone programming (SOCP), is introduced which is solved efficiently and achieve higher SINRs. Not only for its power efficiency improvement, but, also SOCP algorithm reduces the complexity of the extra signalling overhead.
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Chou, Thomas Clayton. "Broadband frequency-independent beamforming." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11854.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (p. 103-105).
by Thomas Clayton Chou.
M.S.
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Van, Tonder Vereese. "Beamforming for radio astronomy." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96126.
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Thesis (MEng) -- Stellenbosch University, 2014.ENGLISH ABSTRACT: Beamforming is a technique used to combine signals from an array of antennas to effectively synthesize a single aperture and beam. In the Radio Astronomy community the technique is used to obtain a desirable beam pattern as well as to electronically point the beam of an array. Next generation radio telescopes such as the Square Kilometre Array (SKA) surpass current technology and will extensively make use of beamforming techniques. Various factors determine the output of a beamformer; however, given an array with a fixed configuration only the weights applied to the incoming signals affect the synthesized aperture and beam. Furthermore, the incoming data must be processed in real-time, at a rate equal to the input-output rate of the processor. Both the weighting function and the real-time implementation of beamforming, are the primary subjects of this thesis. In this thesis various deterministic weighting functions are investigated. The algorithms are implemented in a matlab program, serving as a simulation tool for investigating the techniques. The program is verified by comparing the expected theoretical outcomes to the simulated output. For the program the following functionalities are included: a steering technique, spectral weighting, Dolph-Chebychev, and the Least Square Error algorithm. Applications of these techniques is investigated and their prominence in the Radio Astronomy community is established. For the real-time beamformer implementation, the UniBoard platform configured with beamformer firmware, is investigated. This is important as the UniBoard is an excellent example of a beamformer implementation within the Radio Astronomy community. The architecture is used to emulate a linear array by implementing a python control script, where the output corresponded accurately with the expected theoretical values. The thesis also constitutes the design and implementation of a digital frequency domain beamformer on the ROACH board. This processing board is employed by the Karoo Array Telescope (KAT-7) in South Africa. This work is therefore important as it demonstrates a beamformer implementation on an architecture in use by the Radio Astronomy community. An antenna array is designed and built for the verification of the beamformer design. Results with a good degree of accuracy were obtained and where errors exist they are discussed.
AFRIKKANSE OPSOMMING: Bundelvorming is ’n tegniek waarmee die seine van ’n antenna samestelling gekombineer word om ’n enkele effektiewe stralingsvlak en stralingspatroon te sintiseer. In die Radio Astronomie gemeenskap word die tegniek gebruik om ’n gewenste stralingspatroon te sintiseer sowel as om die rigting van die patroon elektronies te beheer. Die Square Kilometre Array (SKA) is ’n toekomstige radioteleskoop en sal grootliks gebruik maak van bundelvorming tegnieke. Die uitset van bundelvormers word geaffekteer deur verskeie faktore, maar vir ’n gegewe samestelling is dit net die gewigsfunksies wat toegepas word op die inkomende seine wat die gesintiseerde patroon kan beheer. Verder moet die inkomende data verwerk word teen ’n tempo gelykstaande aan die inset-en-uitsetkoers van die verwerker. Die gewigsfunksie so wel as die implementasie van die bundelvormer is albei primêre onderwerpe van die tesis. ’n Verskeindenheid van deterministiese bundelvormingstegnieke sal ondersoek word in hierdie tesis. Die algoritmes is in ’n matlab program geïmplementeer vir simulasie doeleindes. Die program is geverifieër deur die uitset te vergelyk met die verwagte teoretiese waardes. Die program sluit die volgende funksies in: ’n rigting beheer algoritme, spektraalgewigte, Dolph-Chebychev, en die minste vierkantsfout algoritme. Hierdie tegnieke is van belang weens hul toepassing in die Radio Astronomie gemeenskap. Vir die implementasie van ’n bundelvormer is die UniBoard hardeware, geprogrameer in ’n bundelvormings modus, van gebruik gemaak. Hierdie aspek is belangrik omdat die Uni- Board ’n goeie voorbeeld van ’n geïmplementeerde bundelvormer in die Radio Astronomie gemeenskap is. Die UniBoard word gebruik om ’n lineêre samestelling te emuleer deur in python ’n beheer skrip te skryf, waar die uitset van die emuleerder akkuraat ooreenstem met die verwagte waardes. Die tesis behels ook die ontwerp en implementasie van ’n digitale frekwensiegebied bundelvormer op die ROACH platform. Hierdie verwerker word tans gebruik in die Karoo Array Telescope (KAT-7) in Suid-Afrika. Hierdie werk is dus belangrik omdat dit die implementasie van ’n bundelvormer op tegnologie wat huidiglik in die Radio Astronomie gemeenskap gebruik word demonstreer. Daarbenewens is ’n antenna samestelling ontwerp en gebou om die bundelvormer te verifieër. Die resultate is akkuraat tot ’n redelike mate. Waar daar ’n fout onstaan het word dit in die tesis bespreek.
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Venkatasubramanian, Ramasamy. "Beamforming for MC-CDMA." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31287.
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Orthogonal Frequency Division Multiplexing (OFDM) has recently gained a lot of attention and is a potential candidate for Fourth Generation (4G) wireless systems because it promises data rates up to 10Mbps. A variation of OFDM is Multi-Carrier CDMA (MC-CDMA) which is an OFDM technique where the individual data symbols are spread using a spreading code in the frequency domain. The spreading code associated with MC-CDMA provides multiple access technique as well as interference suppression.
Often times in cellular and military environments the desired signal can be buried below interference. In such conditions, the processing gain associated with the spreading cannot provide the needed interference suppression. This research work investigates multi-antenna receivers for OFDM and MC-CDMA systems; specifically this works investigates adaptive antenna algorithms for MC-CDMA for very different channel conditions. Frequency domain beamforming is studied in this research predominantly through simulation. As an alternative a time domain beamforming is also studied.
Time variations in the channel can disrupt the orthogonality between subcarriers. Minimum Mean Square Error (MMSE) detection coupled with MMSE beamforming is proposed for time varying channels. Semi-analytic results are derived to study the Bit Error Rate (BER) performance. These results show significant performance improvement in the presence of interference. Joint MMSE weights in space and frequency is also investigated and semi-analytic results are derived to study their BER performance.Master of Science
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Luo, Zhengwei. "Beamforming for binaural hearing aids." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28170.
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Binaural hearing aids making use of a wireless link are becoming a trend in hearing-aids design. However, it is still not clear how much gain can be obtained in complex real-life acoustic environments when using binaural hearing aids compared to monaural ones, and whether binaural hearing aids are worth the additional effort and complexity. This thesis aims to provide some answers to this question. In particular, it will compare the performance of different microphone array configurations, study the effects of using different head models for fixed beamforming design, assess the effect of head model mismatch and direction of arrival information mismatch, investigate methods to preserve the binaural cues, evaluate combinations of fixed binaural beamforming followed by other noise reduction algorithms, and assess the performance of the different algorithms using both classical beamforming metrics and objective measures related to speech quality and intelligibility.
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Jangam, Ravindra nath vijay kumar. "BEAMFORMING TECHNIQUES USING CONVEX OPTIMIZATION." Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-33934.
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The thesis analyses and validates Beamforming methods using Convex Optimization. CVX which is a Matlab supported tool for convex optimization has been used to develop this concept. An algorithm is designed by which an appropriate system has been identified by varying parameters such as number of antennas, passband width, and stopbands widths of a beamformer. We have observed the beamformer by minimizing the error for Least-square and Infinity norms. A graph obtained by the optimum values between least-square and infinity norms shows us a trade-off between these two norms. We have observed convex optimization for double passband of a beamformer which has proven the flexibility of convex optimization. On extension for this, we designed a filter in which stopband is arbitrary. A constraint is used by which the stopband would be varying depending upon the upper boundary (limiting) line which varies w.r.t y-axis (dB). The beamformer has been observed for feasibility by varying parameters such as number of antennas, arbitrary upper boundaries, stopbands and passband. This proves that there is flexibility for designing a beamformer as desired.
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Liu, Wei. "Digital beamforming employing subband techniques." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422950.
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Ahmad, Nurul Nadia. "Minimum bit error ratio beamforming." Thesis, University of Southampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418966.
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Tan, Shuang. "Minimum error rate beamforming transceivers." Thesis, University of Southampton, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446595.
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Lee, Joyce 1976. "Acoustic beamforming in reverberant environment." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80097.
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Lustberg, Robert Jack. "Acoustic beamforming using microphone arrays." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12338.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1993.Includes bibliographical references (leaves 71-72).
by Robert Jack Lustberg.
M.S.
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Grbic, Nedelko. "Optimal and Adaptive Subband Beamforming." Doctoral thesis, Ronneby : Blekinge Institute of Technology, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00206.
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The increased use of personal communication devices, personal computers and wireless cellular telephones enables the development of new inter-personal communication systems. The merge between computers and telephony technologies brings up the demand for convenient hands-free communications. In such systems the users wish to lead a conversation in much the same way as in a normal person-to-person conversation. The advantages of hands-free telephones are safety, convenience and greater flexibility. In many countries and regions, hand held telephony in cars is prohibited by legislation. By placing the microphone far away from the user a number of disadvantages are introduced, which results in substantial speech distortion and poor sound quality. These disturbances are mainly caused by room reverberation and background noise. Furthermore, acoustic feedback generated at the near-end side is a problem for the far-end side talker, who will hear his/her own voice echoed with 100-200 ms delay, making speech conversation substantially more difficult. Digital filtering may be used to obtain a similar sound quality as for hand held telephony. Three major tasks must be addressed in order to improve the quality of hands-free communication systems; noise suppression, room reverberation suppression, and acoustic feedback cancellation of the hands-free loudspeaker. The filtering operation must perform the above mentioned tasks without causing severe near-end speech distortion. A properly designed broad-band microphone array is able to perform all the given tasks, i.e. speech enhancement, echo cancellation and reverberation suppression, in a concise and effective manner. This is due to the fact that the spatial domain may be utilized as well as the temporal domain. This thesis deals with the problem of specification and design of beamformers used to extract the source signal information. A new subband adaptive beamforming algorithm is proposed, where many of the drawbacks embedded in conventional adaptive beamforming are eliminated. Evaluation in a car hands-free situation show the benefits of the proposed method. Blind signal separation is discussed and a new structure based on frequency domain inverse channel identification and time domain separation, is proposed. Further, filter-bank properties and design are discussed together with performance limitations in subband beamforming structures.Avhandlingen behandlar specifikation och konstruktion av mikrofon-arrayer för att extrahera talinformation. En ny adaptiv delbands beamforming-algoritm föreslås där många av nackdelarna hos konventionella adaptiva beamformers är eliminerade. En utvärdering i en bil med ett frihands-system bekräftar fördelarna med den föreslagna metoden. Blind signal-separation diskuteras och en ny struktur föreslås, baserad på en inverterande kanalidentifiering utförd i frekvensdomän med en kontinuerlig separation utförd i tidsdomän. Filterbanks-egenskaper och designmetoder diskuteras tillsammans med begränsningar som finns i beamforming-strukturer utförda i delband.
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Djamal-Eddine, Berraki. "Beamforming for mmWave communication systems." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.691176.
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Historically, wireless systems were designed to meet the demand of relatively low speed connections for calls, web browsing and emails. However, recent developments in consumer electronics has led to the proliferation of new applications such as High Definition Television, mobile TV, Online Multimedia and high resolution internet which put pressure on wireless systems to meet the generated data traffic. Standards such as IEEE 802.1 lac and LTE-AlB have adopted more advanced configurations such as MTMO architectures, beamforming, spatial sharing and channel aggregation to ease this high demand. However, even with such complex configurations, the highly congested 0-6GHz band is incapable to offer multi-user multi-gigabit wireless performance. This spectmm shortage has motivated the investigation of possible usage of unlicensed/light-licensed mmWave bands within the range of 30-100GHz where large chunks of spectmm are available.
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Zhang, Yuanrui. "Wireless security with beamforming technique." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709882.
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This thesis focuses on the wireless security in the physical layer with beamforming technique. As the wireless communications grow more important, a higher level of security is more demanding as well. New techniques have been proposed in complement to the existing encryption-based methods in the communications protocols. One of the emerging areas is the security enhancement in the physical layer, which exploits the intrinsic properties of the wireless medium. Beamforming, which has been proved to have many advantages, such as increasing data rates and reducing interference, can also be applied to enhance the wireless security. The antenna array is one of the most important factors that affect the secrecy performance of the exposure region based beamforming technique. The potential of using different array geometry and array configuration to improve security is explored. In this thesis, two common arrays, i.e., linear and circular arrays, are considered. Analytic expressions for general array geometry as well as for the linear and circular arrays are derived. In addition, numerical results are used to analyze the behaviors of the antenna array towards security. Based on the empirical results, numerical optimization algorithms are developed to exploit the array configuration to enhance the system security level. In complement to the theoretical analysis, experiments are carried out to study the performance of the beamformer with linear and circular arrays in practice. Especially, the impact of the mutual coupling on the security performance is investigated. To this end, numerical simulation results as well experimental results are used to study the behaviors of the linear and circular arrays towards security.
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Arredondo, Alberto. "Downlink beamforming for mobile communications." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3035934.
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Bartolomé, Calvo Diego. "Fairness Analysis of Wireless Beamforming Schedulers." Doctoral thesis, Universitat Politècnica de Catalunya, 2005. http://hdl.handle.net/10803/6891.
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Aquesta tesi es dedica a l'anàlisi de la justícia a la capa física en entorns de comunicacions amb múltiples antenes i diversos usuaris, cosa que implica un nou punt de vista sobre problemas tradicionals. Malgrat això, el grau d'equitat o desigualtat en la distribució de recursos ha estat estudiat en profunditat en altres camps com Economia o Ciències Socials. En el fons, el enginyers tendeixen a optimizar les prestacions globals, però quan hi ha múltiples usuaris en escena, aquella optimització no és necessàriament la millor opció. En sistemes mòbils, per exemple, l'usuari amb unes males condicions de canal pot patir les conseqüències d'un controlador central que basi les seves decisions en la millor qualitat instantània del canal. En aquest sentit, el problema s'encara des de quatre perspectives diferents: processament d'antenes, assignació de potència, assignació de bits, i combinació de diversitat en espai (SDMA) amb múltiples subportadores (OFDM).Abans del contingut tècnic, es descriu en detall l'entorn on s'emmarca aquesta tesi. La contribució de l'autor com a tal comença amb l'anàlisi de la justícia no només pel processament al transmissor, però també pel límit superior que representa la tècnica cooperativa entre el transmissor i el receptor. L'anàlisi de SNR pel forçador de zeros, el dirty paper i l'estratègia cooperativa entre transmissor i receptor està basada en la teoria de carteres, i consisteix bàsicament a calcular la mitja i la variància de cada esquema. Es veu que una mitja superior ve donada per una major variància en l'assignació de recursos. Així com a aquestes tècniques d'antenes, la justícia hi és implícita, es fa totalment explícita en la tria d'una tècnica de distribució de potència amb un conformador forçador de zeros. Llavors, les funcions objectiu tradicionals a la literatura es comparen en termes de justícia, això és en termes del màxim i el mínim, a més de la mitja o la suma. Aquí es pot veure que optimitzar les prestacions globals d'una cel·la (p.ex tècniques de mínima suma de BER o màxima suma de rate) implica una distribució més desigual dels recursos entre els usuaris. Per una altra banda, les tècniques max-min tendeixen a fer una distribució dels recursos més paritària entre els usuaris, alhora que perden en prestacions globals.
A més, l'assignació de potència basada en teoria de jocs es compara a les tècniques tradicionals, i es mostra que la funció d'utilitat àmpliament utilitzada en aquest context té una taxa d'error inacceptable. Llavors, la funció a optimitzar s'ha de triar de forma acurada, per tal d'evitar possibles conseqüències indesitjables. Un altre problema interessant és el control d'admissió, és a dir, la selecció d'un subconjunt d'usuaris que han de ser servits simultàniament. Normalment, el control d'admissió és necessari per complir els requeriments de les comunicacions, en termes de retard o taxa d'error, entre d'altres. Es proposa un nou algoritme que està entre mig de les tècniques tradicionals a l'eix de la justícia, l'assignació uniforme de potència i l'esquema que dóna igual rate i BER a tots els usuaris.
Després d'això, l'anàlisi de la justícia es fa per l'assignació de bits. Primer, el punt de vista tradicional de la maximització de la suma de rates es contraposa a la maximització de la mínima rate, que finalment assigna a tots el usuaris un número igual de bits. Un altre cop, el controlador central ha de balancejar les necessitats individuals amb les prestacions globals. Malgrat això, es proposa un algoritme que té un comportament intermig entre els esquemes tradicionals. A més, s'estudien una extensió per tal de combinar la diversitat en espai amb la freqüencial, per tant, s'analitzen sistemes SDMA/OFDM, pels quals s'extenen els algoritmes inicialment dissenyats per SDMA. Com que les funcions objectiu són NP-completes i molt difícils de resoldre fins i tot amb un nombre moderat d'usuaris i antenes, les solucions subòptimes són clarament bones candidates. A més, temes pràctics com la senyalització i la reducció en complexitat són tractats des d'un clar punt de vista d'enginyeria.
This dissertation is devoted to the analysis of fairness at the physical layer in multi-antenna multi-user communications, which implies a new view on traditional techniques. However, the degree of equality/inequality of any resource distribution has been extensively studied in other fields such as Economics or Social Sciences. Indeed, engineers usually aim at optimizing the total performance, but when multiple users come into play, the overall optimization might not necessarily be the best thing to do. For instance in wireless systems, the user with a bad channel condition might suffer the consequences from the selective choice based on the instantaneous channel quality made by a centralized entity. In this sense, the problem has four different perspectives: antenna processing, power allocation, bit allocation, and combination of space diversity (SDMA) with multiple subcarriers (OFDM).
Before the technical content, the landscape where this dissertation is contained is described in detail. The contribution of the author starts with the analysis of fairness conducted not only for transmit processing, but also for the upper bound that represents the cooperative strategy between the transmitter and the receiver. The SNR analysis for zero forcing, dirty paper, and the cooperative scheme, is based on portfolio theory, and basically consists of the computation of the mean and the variance of each scheme. Interestingly, a higher mean performance comes at the expense of a higher variance in the resource allocation. Whereas in these antenna array techniques, the fairness is implicit, it is made explicit afterwards by the selection of a power allocation technique with a zero forcing beamforming. The traditional objective functions available in the literature are here compared in terms of fairness, i.e. not only the mean or sum value are analyzed, but also the minimum and the maximum. It can be stated that optimizing the global performance of a cell (e.g. a minimum sum BER or maximum sum rate techniques) comes at the expense of an uneven distribution of the resources among the users. On the other hand, max-min techniques tend to distribute the resources more equally at the expense of loosing in global performance.
Moreover, the game-theoretic power allocation is compared to traditional techniques, and it is shown that the widespread utility function in this context yields an unacceptable BER. Therefore, the optimizing criterion shall be carefully chosen to avoid undesirable operating consequences. Another interesting problem is the admission control, that is, the selection of a subset of users that are scheduled for transmission. Usually, this selection shall be done because the QoS requirements of the communications, e.g. in terms of delay or error rate, prevent all the users from being served. A new algorithm is proposed that balances between the traditional techniques on the extremes of the fairness axis, the uniform power allocation and the equal rate and BER scheme.
After that, the fairness analysis is conducted for the integer bit allocation. First, the traditional approach of the maximization of the sum rate is opposed to the maximization of the minimum rate technique, which ultimately assigns an equal number of bits for all the users. Again, the centralized controller shall balance between the global performance and the individual needs. Nevertheless, an algorithm is proposed, which yields an intermediate behavior among the other traditional schemes. Then, an extension is developed in order to combine the spatial diversity with frequency diversity, that is, SDMA/OFDM systems are analyzed and the initial algorithms for SDMA are extended for such a case. Since the objective functions are NP-complete and very hard to solve even with moderate number of users and antennas, several suboptimal solutions are motivated. Moreover, practical issues such as signaling or a reduction in complexity are faced from a clear engineering point of view.
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As'ad, Hala. "Binaural Beamforming with Spatial Cues Preservation." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33168.
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In binaural hearing aids, several beamforming algorithms can be used. These beamformers aim to enhance the target speech signal and preserve the binaural cues of the target source (e.g. with constraints on the target). However, the binaural cues of the other directional sources as well the background noise are often lost after processing. This affects the global impression of the acoustic scene, and it limits the perceptual separation of the sources by the hearing aids users. To help the hearing aids users to localize all the sound sources, it is important to keep the binaural cues of all directional sources and the background noise. Therefore, this work is devoted to find the best trade-off between the noise/interferers reduction and the cues preservations not only for the directional interferers but also for the background noise based on selection and mixing processes. In this thesis, some classification decision algorithms, which are based on different criteria such as the power, the power difference, and the coherence, are proposed to complete the selection and mixing processes. Simulations are completed using recorded signals provided by a hearing aid manufacturer to validate the performance of the proposed algorithm under different realistic acoustic scenarios. After detailed testing using different complex acoustic scenarios and different beamforming configurations, the results indicate that some of the proposed classification decision algorithms show good promise, in particular the classification decision algorithm based on coherence.
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Ryan, James G. "Near-field beamforming using microphone arrays." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0015/NQ48335.pdf.
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Coey, Tyson Curtis. "Round-trip time-division distributed beamforming." Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-071007-124515/.
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Yu, Lei. "Robust adaptive beamforming with coherent interferences." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.537988.
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Goh, Boon Aik. "Adaptive subband beamforming for microphone arrays." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424021.
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Ma, Jingxiao. "Adaptive beamforming for distributed relay networks." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/19584/.
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Tremendous research work has been put into the realm of distributed relay networks, for its distinct advantages in exploiting spatial diversity, reducing the deployment cost and mitigating the effect of fading in wireless transmission without the multi-antenna requirement on the relay nodes. In typical relay networks, data transmission between a source and a destination is assisted by relay nodes with various relaying protocols. In this thesis, we investigate how to adaptively select the relay weights to meet specific interference suppressing requirements of the network. The thesis makes original contributions by proposing a filter-and-forward (FF) relay scheme in cognitive radio networks and an iterative algorithm based transceiver beamforming scheme for multi-pair relay networks. In the firstly proposed scheme, the relay nodes are adapted to deal with the inter-symbol-interference (ISI) that is introduced in the frequency-selective channel environment and the leakage interference introduced to the primary user. Our proposed scheme uses FF relay beamforming at the relay nodes to combat the frequency selective channel, and our scheme also aims to maximize the received SINR at the secondary destination, while suppressing the interference introduced to the primary user (PU). This scheme is further extended to accommodate a relay nodes output power constraint. Under certain criteria, the extended scheme can be transformed into two sub-schemes with lower computational complexity, where their closed-form solutions are derived. The probability that we can perform these transformations is also tested, which reveals under what circumstances our second scheme can be solved more easily. Then, we propose an iterative transceiver beamforming scheme for the multi-pair distributed relay networks. In our scheme, we consider multi-antenna users in one user group communicating with their partners in the other user group via distributed single-antenna relay nodes. We employ transceiver beamformers at the user nodes, and through our proposed iterative algorithm the relay nodes and user nodes can be coordinatively adapted to suppress the inter-pair-interference (IPI) while maximize the desired signal power. We also divide the rather difficult transceiver beamforming problem into three sub-problems, each of which can be solved with sub-optimal solutions. The transmit beamforming vectors, distributed relay coefficients and the receive beamforming vectors are obtained by iteratively solving these three sub-problems, each having a closed-form solution. The tasks of maximizing desired signal power, and reducing inter-pair interference (IPI) and noise are thus allocated to different iteration steps. By this arrangement, the transmit and receiver beamformers of each user are responsible for improving its own performance and the distributed relay nodes can be employed with simple amplify-and-forward(AF) protocols and only forward the received signal with proper scalar. This iterative relay beamforming scheme is further extended by distributing the computation tasks among each user and relay node, through which high computational efficiency can be ensured while extra overhead of bandwidth is need for sharing beamforming vector updates during the iteration steps. Furthermore, with respect to the channel uncertainty, two more relay strategies are proposed considering two different requirements from the communication network: sum relay output power and individual relay output power. At last, the application of the iterative relay beamforming method in cognitive radio networks is studied, where multiple pairs of users are considered as secondary users (SUs), and the designed transmit beamforming vector, relay beamforming vector and receive beamforming vector together guarantee that the inner interference of their transmissions is well suppressed while the interference introduced by them to the PU is restricted under a predefined threshold.
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Payami, Sohail. "Hybrid beamforming for massive MIMO systems." Thesis, University of Surrey, 2017. http://epubs.surrey.ac.uk/842311/.
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Massive multiple-input multiple-output (MIMO) technology is considered as one of the enabling technologies to scale up the data rates for the future communication systems. Traditional MIMO systems employ digital beamforming where each antenna element is equipped with one radio frequency (RF) chain. When the number of the antennas are scaled up, the cost and power consumption of massive MIMO systems also increase significantly. Recently, hybrid analog-and-digital beamformers have attracted a lot of attention as a cost effective approach to benefit from the advantages of massive MIMO. In hybrid structure, a small number of RF chains are connected to a large number of antennas through a network of phase shifters. The optimal hybrid beamforming problem is a complex nonconvex optimization due to the nonconvex constraint imposed by phase shifters. The overall objective of this thesis is to provide simple and effective hybrid beamforming solutions for narrowband point-to-point and multiuser massive MIMO scenarios. Firstly, hybrid beamforming problem for a point-to-point communication system with perfect channel state information (CSI) is investigated, and an effective codebook based hybrid beamforming with low resolution phase shifters is proposed which is suitable for sparse scattering channels. Then, by leveraging the properties of massive MIMO, an asymptotically optimal hybrid beamforming solution as well as its closed-form formula will be presented. It will be shown that the proposed method is effective in both sparse and rich scattering propagation environments. In addition, the closed-form expression and lower-bounds for the achievable rates are derived when analog and digital phase shifters are employed. Secondly, hybrid beamforming problem to maximise the total sum-rate for the downlink of multiuser MIMO is investigated, and an effective solution as well as its closed-form expression for this system is proposed. The presented solutions for the single-antenna and multiantenna scenarios are shown to be effective as they can achieve a similar sum-rate as digital beamforming can reach. In addition, it is shown that the proposed technique with low-cost low resolution phase shifters at the RF beamformer demonstrates a comparable performance to that of a hybrid beamformer with an expensive analog beamformer. Finally, two novel hybrid beamforming techniques are proposed to reduce the power consumption at the RF beamformer. Defining a threshold level, it is shown that half of the phase shifters could be turned off without a performance loss when the wireless channel matrix is modeled by Rayleigh fading. Then, we reduce the number of the phase shifters by using a combination of phase shifters and switches at the RF beamformer. The proposed methods can significantly reduce the power consumption as switches, in general, have lower power consumption compared to phase shifters. It is noted that the presented algorithms and the closed-form expressions of their performance are derived by using the asymptotic properties of the elements of the singular vectors for the rich scattering channel matrix.
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Godoy, Elizabeth C. "Antenna beamforming for infrastructureless wireless networks." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41638.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Page 94 blank.
Includes bibliographical references (p. 92-93).
Our work studies the impact of antenna beamforming on the performance of infrastructureless wireless networks. Based on examination of the beampattern for a uniform circular antenna array (UCAA) utilizing beamforming under a constraint on maximum average transmit power, we approximate achievable user data rates as a function of the number of antenna elements, and we examine the behavior of these rates in a simple network with varying noise power and interference and with different scheduling of user transmissions. We find that user data rates increase with the number of antenna elements up to a point of saturation determined by the antenna size and carrier wavelength. Moreover, in some cases that we outline, judicious scheduling of user transmissions can increase achievable data rates.
by Elizabeth C. Godoy.
M.Eng.
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Yudong, He, Yang Xianghua, Zhou Jie, Zhou Banghua, and Shao Beibei. "ROBUST ADAPTIVE BEAMFORMING WITH BROAD NULLS." International Foundation for Telemetering, 2007. http://hdl.handle.net/10150/604533.
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ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, NevadaRobust adaptive beamforming using worst-case performance optimization is developed in recent years. It had good performance against array response errors, but it cannot reject strong interferences. In this paper, we propose a scheme for robust adaptive beamforming with broad nulls to reject strong interferences. We add a quadratic constraint to suppress the power of the array response over a spatial region of the interferences. The optimal weighting vector is then obtained by minimizing the power of the array output subject to quadratic constrains on the desired signal and interferences, respectively. We derive the formulations for the optimization problem and solve it efficiently using Newton recursive algorithm. Numerical examples are presented to compare the performances of the robust adaptive beamforming with no null constrains, sharp nulls and broad nulls. The results show its powerful ability to reject strong interferences.
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Gitlin, Thomas, Diem V. Nguyen, Marc Harlacher, and Robert Smarrelli. "NEXT GENERATION TDRSS MA BEAMFORMING SUBSYSTEM." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/608273.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaThe Tracking and Data Relay Satellite System (TDRSS) Multiple Access (MA) Return Service provides a communication path that originates at a customer platform (either a spacecraft or other type of emitter) and is routed through a geosynchronous Tracking and Data Relay Satellite (TDRS) back to a customer control center or data acquisition location. Conventional operations provide Space Network (SN) customers with MA Service based on a schedule generated from user requests. The MA Service currently provides return link telemetry services to customer platforms with real-time, playback, and science data rates up to 100 kbps. This paper describes an integrated approach, using state-of-the-art technology and fault-tolerant architecture, to develop the next generation of TDRSS MA beamforming equipment. New designs will result in significant reduction in beamformer size and cost by at least an order of magnitude relative to the current MA equipment. This new equipment will provide the potential for increased usage of TDRSS MA services. The paper describes the in-development Demand Access (DA) Return Service that provides a new class of service using next generation technology.
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Manda, Manoj Sai. "Communication Channel Analysis for Efficient Beamforming." Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-20776.
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In this modern communication era, we are surrounded by unlimited electronic devices, the need to connect with everyone and everything increases dramatically. As the number of electronic devices increases, the amount of data to process increases and the need for higher data speeds occurs. After 1G and 2G, LTE (Long Term Evolution, 3G) come with the improvements in technology which allows reaching those new high data rates. Next comes the upgraded version of LTE called LTE-Advanced, which was launched to boost the speeds further. In this thesis, a 4G LTE environment has been created using (Graphic User Interface) in MATLAB. Many characteristics and parameters can be tuned such as type of modulation, number of UEs, type of channel, channel scenario, and some others to know how the system behaves and varied results outcome. Focus on the presence of a line of sight between the receiver and the transmitter helps to distinguish the Rayleigh and Rician scenario. In this thesis simulations on different channel models are simulated and various beamforming algorithms are tested to estimate that line of sight component (K-factor) and Error vector magnitude. The main aim of the thesis is to understand the communication channel behaviour in Static (Line of sight between transmitter and receiver) condition and High-Speed Train Condition along with EPA, EVA, ETU. The other aim of this report is to use the channel knowledge comprises of signal to noise ratio (SNR), bit error rate (BER) and error vector magnitude (EVM) helps to reduce the number of computations required while performing beamforming by varying the beam weight resolution.
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Chuang, Ying Chieh. "Blind Adaptive Beamforming for GNSS Receivers." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440141128.
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Kang, Deokwon. "MIMO beamforming in multiuser wireless environments." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 81 p, 2009. http://proquest.umi.com/pqdweb?did=1885755741&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Chan, Chee Wai. "Distributed beamforming in wireless sensor networks." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FChan.pdf.
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Thesis (M.S. in Engineering Science (Electrical Engineering))--Naval Postgraduate School, Dec. 2004.Thesis Advisor(s): Murali Tummala, Roberto Cristi. Includes bibliographical references (p. 79-81). Also available online.
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Vanucci, Paulo Sérgio Torquato. "Ensaio em túnel de vento de dispositivos para redução de ruído em ponta de flape em um modelo 30P30N." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18148/tde-17052013-140838/.
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Com o desenvolvimento dos motores turbofan, a contribuição das estruturas hipersustentadoras no ruído total gerado pelas aeronaves tem se tornado mais considerável. Sendo que as estruturas do flape tornaram-se uma das principais fontes de ruído. Dispositivos para redução do nível sonoro nessas regiões são investigados em uma asa MD 30P30N, ensaiada em um túnel de vento adaptado para medições aeroacústicas. A localização das fontes de ruído foi obtida através de uma antena de Beamforming (técnica de identificação de fontes acústicas) com 109 microfones, dos quais 60 deles são de alta freqüência (até 40 kHz). As características aerodinâmicas foram avaliadas através de medidas de pressão na superfície do modelo, e com o mapeamento de vórtice em ponta de flape. Dentre os dispositivos avaliados para redução de ruído, foram testadas chapas porosas de diversos tamanhos. Os sinais dos microfones foram processados com o algoritmo DAMAS2 para obtenção dos espectros do Beamforming em uma região de interesse definida. As configurações com porosidade têm nível de ruído equivalente para freqüências até 2000 Hz. A partir daí, há uma redução de até 6 dB em 3200 Hz em relação ao baseline (tipo de teste aplicado à asa). Os resultados de Beamforming para duas configurações diferentes, baseline e chapa porosa foram apresentados usando uma faixa dinâmica de 12 dB, com pico de 58 dB. Observa-se que houve redução dos níveis de ruído na região selecionada. A perda de pressão total na ponta do flape mostrou que há uma aparente correlação entre o gradiente da pressão total e o nível de ruído. Estudos adicionais são necessários para entender os mecanismos de redução de ruído e assim otimizar a geometria das chapas porosas. No entanto, os resultados apresentados indicam que esses dispositivos são candidatos para aplicação em aeronaves.With the development of high-bypass turbofan engines, the airframe contribution to the total aircraft noise has become considerable. One of the largest sources of airframe noise is the flap side-edge, which is investigated experimentally in a MD 30P30N wing. Several devices are also tested to reduce the side-edge noise, especially porous plates. Wind tunnel testing is carried out and the position of noise sources and their levels is obtained with a beamforming antenna. It has 112 microphones, in which 60 of them are suitable for acoustic measurements of up to 40 kHz. The aerodynamic characteristics are evaluated with pressure measurements on the model surface, as well as with vortex mapping on the flap side-edge. To evaluate the noise levels, microphone signals were processed with the DAMAS2 algorithm. Beamforming spectra were then obtained considering only the side-edge region. The baseline configuration and those with porous plates were tested and equivalent noise levels were obtained up to 2000 Hz. For higher frequencies, the model with porous plates has a lower noise level, reaching a difference of 6 dB in 3200 Hz, compared to the baseline configuration. Vortex mapping was carried out with a seven hole Pitot probe developed at the University for the measurement of flows with high angularity. The results for the baseline configuration allows to correlate aerodynamic and aeroacoustic data. This helps to design the side-edge region with a low noise level. Additional studies are necessary to understand the mechanisms of noise reduction and to optimize the geometry of the porous plate. However, the presented results indicate that this device is a candidate for application in aircraft, in special by its superior durability compared to the foam generally used for noise attenuation.
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Zhang, Jie. "Blind adaptive cyclic filtering and beamforming algorithms /." *McMaster only, 2001.
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Lundström, Tomas. "Matched Field Beamforming applied to Sonar Data." Thesis, Linköping University, Department of Electrical Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-16338.
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Two methods for evaluating and improving plane wave beamforming have beendeveloped. The methods estimate the shape of the wavefront and use theinformation in the beamforming. One of the methods uses estimates of the timedelays between the sensors to approximate the shape of the wavefront, and theother estimates the wavefront by matching the received wavefront to sphericalwavefronts of different radii. The methods are compared to a third more commonmethod of beamforming, which assumes that the impinging wave is planar. Themethods’ passive ranging abilities are also evaluated, and compared to a referencemethod based on triangulation.Both methods were evaluated with both real and simulated data. The simulateddata was obtained using Raylab, which is a simulation program based on ray-tracing. The real data was obtained through a field-test performed in the Balticsea using a towed array sonar and a stationary source emitted tones.The performance of the matched beamformers depends on the distance to the tar-get. At a distance of 600 m near broadside the power received by the beamformerincreases by 0.5-1 dB compared to the plane wave beamformer. At a distance of300 m near broadside the improvement is approximately 2 dB. In general, obtain-ing an accurate distance estimation proved to be difficult, and highly dependenton the noise present in the environment. A moving target at a distance of 600 mat broadside can be estimated with a maximum error of 150 m, when recursiveupdating of the covariance matrix with a updating constant of 0.25 is used. Whenrecursive updating is not used the margin of error increases to 400 m.
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Legg, Mathew. "Microphone phased array 3D beamforming and deconvolution." Thesis, University of Auckland, 2012. http://hdl.handle.net/2292/17820.
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Microphone phased arrays are used to generate acoustic maps showing the position and Magnitude of sound sources. Deconvolution of these acoustic maps, which are generated using beamforming, is commonly performed to remove sidelobe artifacts so that it is possible to accurately describe the position and magnitude of the sound source distribution. Traditionally beamforming and deconvolution have used a 2D scanning surface, which is orientated perpendicular to the array axis, but errors can arise when imaging 3D objects. The work in this thesis investigates the use of a deconvolution algorithm for 3D beamformed maps and compares the results to those obtained using traditional 2D acoustic scanning surfaces. Microphone phased array hardware and 3D objects were designed and built. Acoustic maps were generated by attaching mini speakers onto the surface of an object and performing beamforming and deconvolution for both traditional 2D scanning surfaces and 3D scanning surfaces corresponding to the 3D surface geometry of the object. The 3D surface geometry was obtained using computer vision techniques. For more complex objects or where no CAD model of the object exists, structured light scanning was used to obtain an accurate scan of the 3D surface of the object. The scan points obtained using the above two methods were in the reference frame of the primary optical camera in the array. To enable these scan points to be used for beamforming and deconvolution, a microphone position calibration technique was developed which automatically found the coordinates of the microphones, in the reference frame of the primary camera in the array, using computer vision techniques and audio time of flight measurements. This technique was extended to enable dense point clouds of experimental deconvolution errors to be automatically obtained as a function of the frequency and location of the sound sources. These point clouds were used to analyse the deconvolution errors for 3D and traditional 2D scanning surfaces. The data obtained showed that using the 3D scanning surface corresponding to the surface geometry of the object gave more accurate sound pressure levels and, at higher frequencies, more accurate positioning of sound sources than the 2D case.
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Appilla, Chakravarthula Rohan, and Chaithanya Kumar Reddy Veluru. "Intelligent Beam Weight Computation for Massive Beamforming." Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-15181.
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LTE (Long Term Evolution) is likely the most complex wireless system ever developed. It incorporates features that could not have been economically implemented as recently as a decade ago. Today, with large-scale ICs, LTE can be easily accommodated in base stations and battery-powered handsets alike. LTE-Advanced is the upgraded version of LTE technology for providing more speed and greater reliability. In this report, the wireless communication between the user and base station is implemented by creating 4G LTE environment in MATLAB. Impact of Coherence time on beam weight computation varies for different delay profiles. Moreover, SNR of the transmitted signal varies significantly by the time gap between two successive uplink frames in TDD configuration. In this report, computationally efficient algorithm for reducing beam weight computations in system level LTE simulations is proposed. The wireless channel is modelled in both Rician and Rayleigh fading channel. Efficiency of beam forming algorithms is observed at different channel conditions like delay profile, fading channel, bandwidth, correlation, modulation technique. The MUSIC algorithm is implemented for detecting the movement of the users in Line of sight condition
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Abbas, Hatem. "Beamforming techniques for millimeter wave relay networks." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/beamforming-techniques-for-millimeter-wave-relay-networks(6cbbe216-9596-4eaf-9ee3-cd7355d5da7f).html.
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The energy and data rate requirements for the next generation cellular networks urge the need for innovative solutions. Inspired by its massive bandwidth, millimeter wave (mmWave) band is thought-out to be one of the key elements to meet the aspirations. However, mmWave links are known to have short coverage distance due to the propagation losses introduced at high frequencies. The proposed solutions to overcome the transmission challenges include using large arrays with improved directivity, adopting smaller cells, and relying on cooperative networks to extend the mmWave link and avoid shadowing areas. This work aims to improve the connectivity of the mmWave link in the outdoor environments. One of the cost effective methods is to increase the array gain by using Analogue Beamforming (ABF). The performance of the ABF system in the presence of phase quantization error has been analytically investigated. The study also includes comparing three different channel sounding techniques, namely: exhaustive search, side-to-side search, and n-tier search. The time overhead related to each method and their energy consumption are calculated. The numerical results assist in determining the optimum search period to obtain a reasonable spectral efficiency using minimal power consumption. The results also help identify the minimum number of quantization bits required to produce about ninety percent of the optimistic results. In order to extend the coverage further, relay networks are considered an essential component in mmWave communications. The performance of a single hybrid beamforming full-duplex relay system and multi-relay networks were investigated. The design algorithms for the processors in the network are proposed based on the greedy pursuit approach. The performance of the proposed algorithms is analysed under various scenarios. The analysis highlights the influence of the array size, the number of RF chains, and the length of the channel sounding period. The performance of the proposed systems is compared from both the spectral efficiency and power consumption prospects. The results also establish that the number of antennas at the source and the relay receiver arrays have a superior impact on the system performance than the sizes of the array at the destination and the relay transmitter.
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Uthansakul, Monthippa. "Wideband beamforming employing fully spatial signal processing /." [St. Lucia, Qld.], 2006. http://adt.library.uq.edu.au/public/adt-QU20070503.135836/index.html.
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Chan, Chun Man. "Distributed beamforming in man portable communication networks." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Dec%5FChan.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 2007.Thesis Advisor(s): Jenn, David. "December 2007." Description based on title screen as viewed on January 18, 2008. Includes bibliographical references (p. 91-94). Also available in print.
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Yermeche, Zohra. "Soft-constrained subband beamforming for speech enhancement /." Karlskrona : Department of Signal Processing, School of Engineering, Blekinge Institute of Technology, 2007. http://www.bth.se/fou/forskinfo.nsf/allfirst2/966871d2942b946ac1257392004515c1?OpenDocument.
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Kocaman, Ibrahim. "Distributed beamforming in a swarm UAV network." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://bosun.nps.edu/uhtbin/hyperion-image.exe/08Mar%5FKocaman.pdf.
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Thesis (M.S. in Electronic Warfare Systems Engineering)--Naval Postgraduate School, March 2008.Thesis Advisor(s): Jenn, David. "March 2008." Description based on title screen as viewed on May 1, 2008. Includes bibliographical references (p. 71-73). Also available in print.
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Greenberg, Julie Elise. "A real-time adaptive-beamforming hearing aid." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14504.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1989.Includes bibliographical references (leaves 67-69).
by Julie Elise Greenberg.
M.S.
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Karagozyan, Kapriel. "A multi-processor based digital beamforming system." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14754.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1988.Title as it appeared in M.I.T. Graduate List, June 1988: A multiprocessor based design of a digital beam forming system.
Bibliography: leaf 89.
by Kapriel Kargozyan.
M.S.
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Chen, H. "Beamforming optimization for two-way relay channel." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1421150/.
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In this thesis, we focus on the optimization of the two-way relay channel (TWRC), which can double the data rate of communications comparing to the traditional one-way relay channel (OWRC). Because of the broadcasting nature of wireless transmissions, secure transmission is an appealing research topic. We take secrecy rate consideration into the optimization of the TWRC. Overall we provide near-optimal solutions for the secrecy rate maximization problems of the TWRC with imperfect channel state information (ICSI). A much lower complexity optimal SOCP solution is provided for SNR balancing of the TWRC without secrecy consideration. We first look at a flat fading TWRC network model with a multiple-input multiple-output (MIMO) relay where perfect channel state information (CSI) is assumed available. We then formulate an optimization problem, with the objective to minimize the relay’s power usage under the constraints that the signal-to-noise ratio (SNR) of the two transceivers should exceed a preset threshold. A low-complexity optimal beamforming solution is provided to this optimization problem by reformulating it in the form of second-order cone programming (SOCP). Later in the thesis, we consider the presence of an eavesdropper and address the beamforming optimization for minimizing the relay’s power with the constraints of the secrecy rates of the two transceivers. A semi-definite programming (SDP) based searching algorithm is proposed to find a near-optimal solution. For each search of the proposed approach, the previous non-convex optimization problem is transferred into an SDP problem, which can guarantee the optimality of the beamforming matrix. Afterwards, more realistic imperfect CSI (ICSI) situations are considered for the TWRC network models. As ICSI completely changes the structure and the property of the optimization problems, we reformulate the optimization problems into two scenarios. For the first case, we consider that the relay is an untrusted eavesdropper and in this case an SDP solution is provided to maximize the joint-decoding sum-secrecy rate. For the second case, we investigate the robust beamforming problems where the relay is trusted but there is an external eavesdropper, another SDP solution is provided to maximize the sum-secrecy rate.
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Nichols, Brendan. "Vector-sensor beamforming for autonomous glider networks." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54420.
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Detection and localization of sound sources in an ocean environment can be achieved with a distributed array of passive acoustic sensors. Utilizing an array of autonomous littoral gliders, which offer long-term and quiet operation, and vector sensors, which measure both acoustic pressure and particle velocity, the array's localization performance can be improved. However, vector sensors are susceptible to errors induced by acoustic noise, and autonomous gliders as a sensor platform introduce positional errors. Through both simulations and at-sea data, the localization performance of four processing methods are evaluated under various noisy conditions. In both simulated and at-sea data results, a new cross-coherent method outperforms traditional methods by mitigating the effects of acoustic noise, provided sufficient positional accuracy of the array elements.
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Kelkar, Anand, Norm Lamarra, and Daniel Gonzalez. "FROM RF TO BITS WITH SYNTHETIC BEAMFORMING." International Foundation for Telemetering, 2006. http://hdl.handle.net/10150/604414.
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ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, CaliforniaA Synthetic Beamforming antenna was built for Airborne Telemetry. Low-Noise Block-converters translated RF to IF suitable for direct analog-to-digital conversion. Then all telemetry functions were performed digitally via parallel FPGAs for 10 independent sources. Monopulse tracking and optimal diversity combination was performed using 4 antenna quadrants at two orthogonal polarizations. Novel estimation approaches drove digital demodulation, symbol- and bit- synchronization. Final telemetry outputs include: digital, analog (video), and analog IF (e.g., for downlink relay). This program has incubated several concepts that we believe have the combined potential to significantly improve the future of telemetry.
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Thiel, Ryan. "Array Processing Techniques for Broadband Acoustic Beamforming." ScholarWorks@UNO, 2005. http://scholarworks.uno.edu/td/251.
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Audio acquisition and recording can benefit from directional reception of the acoustic signals. Current acoustic designs of highly-directional microphones are bandwidth limited and physically large. A microphone array used in conjunction with a beamforming algorithm can acquire and spatially filter the signal, but traditionally this has suffered from limitations similar to those of the purely acoustic designs. The work presented in this paper attempts to overcome these limitations by producing and analyzing three atypical techniques for broadband beamforming. The last and most successful technique employs an algorithm which calculates the difference in group delay of the acquired signals and uses that information to determine the direction of the incoming signals as a function of frequency.
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Sirousi, Sorena. "Distributed Digital Beamforming Techniques in Satellite Networks." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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In recent years, satellite communication systems, in particular LEO constellations, have been subject of increased attention in the new space race; this is substantiated by the numerous industrial endeavors aiming at providing high-speed broadband access anywhere at anytime, E.G., SpaceX Starlink. In 5G systems, there has been an increased focus to integrate a non-terrestrial component into the broader wireless communication infrastructure. It is expected that this trend will continue in the future. Satellites can provide coverage in areas where a terrestrial infrastructure is congested or unavailable; however, their energy resources are limited and due to the sidelobes in the multiple beam coverage, co-channel interference arises. Here, beamforming is an effective remedy for both problems.
In this thesis, a distributed beamforming solution is investigated and compared with classic centralized methods. The distributed solution benefits from the fact that beamforming is not performed in a centralized manner in a single satellite, but is done collectively. So, if one satellite malfunctions, others can still provide coverage. Lastly, numerical simulations performed in MATLAB substantiate the advantages of distributed beamforming approach.
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Miranda, Ricardo Kehrle. "Beamforming techniques for next generation communication systems." reponame:Repositório Institucional da UnB, 2017. http://repositorio.unb.br/handle/10482/24564.
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Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2017.Submitted by Raquel Almeida (raquel.df13@gmail.com) on 2017-07-19T14:37:10Z No. of bitstreams: 1 2017_RicardoKehrleMiranda.pdf: 3690571 bytes, checksum: 3c3d7498829ea2944d09d5fb3d939554 (MD5)
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Comunicações digitais, seja por voz, mensagens instantâneas, vídeo ou outro conteúdo de mídia, se tornaram uma parte essencial da sociedade moderna. Como consequência, a demanda por sistemas avançados de comunicação está aumentado. Atualmente, as redes de comunicação móvel têm um total de 7,3 bilhões de assinaturas em todo o mundo, das quais 1,4 bilhão pertencem à rede mais nova da quarta geração (4G). Para 2022, são esperadas 8,9 bilhões de assinaturas, sendo 4,3 bilhões de assinaturas 4G. Além disso, também são previstas aplicações que requerem uma alta taxa de transmissão como a realidade virtual (VR). Os sistemas de comunicação também devem alocar a crescente demanda de comunicações máquina a máquina, incluindo a internet das coisas (IoT), redes veiculares e ad hoc (VANETs), como as redes veículo a veículo (V2V) e comunicações veículo a infraestrutura (V2I). Para suportar esta demanda, um aumento na escala de 100 vezes está sendo considerado como um requisito para os padrões de comunicação da futura quinta geração (5G), à qual tem seu emprego previsto para 2020. Uma das tecnologias chaves para permitir uma melhor exploração do escarço espectro é a incorporação de arranjos de antenas aos dispositivos de comunicação. Particularmente, este trabalho tem foco em técnicas de formação de feixe, que podem virtualmente adaptar o padrão de irradiação de um arranjo de antenas de forma a amplificar sinais vindos de uma direção desejada e cancelar sinais vindos de outros ângulos. Portanto, formadores de feixe promovem a separação espacial de múltiplas fontes de sinal, que compartilham uma mesma banda do espectro e, além disso, também podem ser aplicados para mitigação de interferência. Neste trabalho, técnicas e frameworks de formadores de feixe são desenvolvidos levando em conta ruído colorido, arranjos uniformes retangulares (URAs) e sinais banda larga. Para cenários com ruídos coloridos, técnicas de branqueamento, redução de posto e uma transformação são utilizadas. Para a URA e casos banda larga é utilizada uma notação tensorial e a decomposição por meio da análise de fatores paralelos (PARAFAC) é aplicada juntamente com formadores de feixe invariantes em frequência (FIBs). Por fim, um método de avaliação com baixo custo computacional é desenvolvida por meio da transformada da incerteza (UT).
Digital communications, either voice, messaging, video or other media content, have become an essential part of the modern society. As a consequence, the demand for advanced digital communication systems is increasing. Currently, mobile networks have a total of 7.3 billion subscriptions worldwide, from which 1.4 billion belong to the latest fourth generation (4G) network. In 2022, 8.9 billion subscriptions are expected, being 4.3 billion for 4G. Moreover, applications that require a high throughput such as virtual reality (VR) are also foreseen. The communication systems should also fit increasing demands of machine to machine communications, including Internet of things (IoT) and vehicular ad hoc networks (VANETs), such as vehicle to vehicle (V2V) and vehicle to infrastructure (V2I) communications. To support this demand, a 100 fold increase in data rate is being considered as a requirement for future fifth generation (5G) standards, whose deployment starts as early as 2020. One of the key technologies to allow for a better exploitation of the scarce spectrum is the incorporation of antenna arrays into communication devices. In particular, this work focusses on beamforming techniques that can virtually adapt the irradiation pattern of the antenna array based device in order to amplify the signals from a desired direction and to cancel out the interference from other angles. Therefore, beamforming provides the spatial separation of multiple sources sharing the same spectrum band, and can also be applied to mitigate jamming and radio interference. In this work beamforming techniques and frameworks to deal with colored noise scenarios, uniform rectangular arrays (URA) and broadband scenarios are developed. For colored noise scenarios, prewhitening techniques, rank reduction techniques and a transformation are used. For the URA and the broadband scenarios, a tensor notation is adopted and the parallel factor analysis (PARAFAC) tensor decomposition is used along with frequency invariant beamformers (FIBs). Finally, a low computational cost evaluation method that uses the unscented transformation is developed.