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1
Kleynhans, Waldo. "On channel estimation for mobile WiMAX." Diss., Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-01262009-102433/.
Повний текст джерела
2
Barber, Don E. "Geolocation of WiMAX subscriber stations based on the timing adjust ranging parameter." Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Dec/09Dec%5FBarber.pdf.
Повний текст джерелаАнотація:
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 2009.Thesis Advisor(s): McEachen, John C. ; Loomis, Herschel H. Second Reader: Garcia, Vicente C. "December 2009." Description based on title screen as viewed on January 27, 2010. Author(s) subject terms: 802.16, WiMAX, geolocation, ranging, timing adjust. Includes bibliographical references (p. 71-72). Also available in print.
3
Kim, Ngan Trieu, and Olumide Ajiboye. "PERFORMANCE ANALYSIS OF ADAPTIVE ARRAY SYSTEM AND SPACE-TIME BLOCK CODING IN MOBILE WIMAX (802.16e) SYSTEMS." Thesis, Blekinge Tekniska Högskola, Avdelningen för telekommunikationssystem, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-4743.
Повний текст джерелаАнотація:
We live in an information hungry age, we generate and process information at a rate never before recorded in the history of mankind. Today’s computing platforms are run on Gigahertz multi-core processors churning out Gigabits streams of data that need to be transmitted as quickly as possible. Often times the source and the destination are mobile which means wired connections are not a choice. This has led to an ever increasing need to develop wireless access technologies that support high throughput regardless of the transmission environment. Till date, many proprietary solutions exist that seek to bridge this gap with little or no support for interoperability. For the sheer scale of development that is required, a standard based solution is the key. The IEEE 802.1x committee oversees the development of standards for wireless systems, it formed the 802.16 working group to develop a standards-based Wireless Metropolitan Area Network (MAN) solution. One of the fruits of this effort is the 802.16e standard fondly referred to as mobile WiMAX and it is the subject of study in this thesis. This thesis seeks to analyze the transmission characteristics of two of the antenna systems defined in the standard i.e. Adaptive Beamforming Systems and Multiple-Input Multiple-Output Systems. Multiple-Input Multiple-Output (MIMO): utilizes multiple antennas at the transmitter and receiver to provide diversity gain, multiplexing gain or both. Adaptive Antenna Systems (AAS): Adaptive array system uses an antenna array to generate in real-time radiation patterns with the main lobes and/or nulls dynamically tuned to specific directions in order to increase or suppress signal power in that direction.Worldwide Interoperability for Microwave Access (WiMAX) is the acronym for Institute of Electrical and Electronics Engineers (IEEE) 802.16 set of standards governing Air Interface for Fixed Broadband Wireless Access Systems. In the history of wireless systems, WiMAX is revolutionary technology as affords its users the Wi-Fi grade throughput and cellular system level of mobility. With WiMAX, broadband technology (traditionally ADSL and Fiber) goes wireless and WiMAX users can basically enjoy triple-play application, and split-second download and upload rates. WIMAX also offers full mobility much as traditional cellular systems do with features like seamless hand-over and roaming at vehicular speed; this is made possible because the system design covers the access network to core network. For the operator, WiMAX is a welcome development because it merges traditional cellular networks with broadband technology thus opening them to more business offerings and a larger client base and all this at a reduced cost of deployment. Base stations are comparatively cheaper and do not require extensive planning typical of other cellular systems thus WiMAX is aptly suited for emerging markets where infrastructure cost is a major issue; little wonder a lot of 3rd world countries have signified interest in the technology.
4
Salmon, Brian P. "Optimizing LDPC codes for a mobile WiMAX system with a saturated transmission amplifier." Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-01262009-160431/.
Повний текст джерела
5
Mandal, Arpan. "Mobile WiMAX : pre-handover optimization using hybrid base station selection procedure : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Engineering in Electrical and Computer Engineering in the University of Canterbury /." Thesis, University of Canterbury. Electrical and Computer Engineering, 2008. http://hdl.handle.net/10092/1258.
Повний текст джерелаАнотація:
A major consideration for mobile WiMAX is seamless handoff. The British English term for transferring a cellular call is handover whereas the Americans prefer to call it handoff. Cellular-based standards have the advantage of many years experience in handover for voice calls, while for broadband mobility in itself is no mean feat, and handover is still a challenge. Mobile IP, with "slow" handover, will be fine for web-browsing but not good enough for decent voice quality. Many services require the appearance of seamless connections (VoIP, VPNs, etc). Much of the complexity (and latency) in the cellular network is from maintaining these connections across cell boundaries. Handovers in wireless technologies have always been a challenging topic of discussion. According to the mobility framework of IEEE 802.16e, a Mobile Station (MSS) should scan the neighbouring Base Stations (BSs) for selecting the best BS for a potential handover. However, the standard does not specify the number of BSs to be scanned leaving room for unnecessary scanning. Moreover, prolonged scanning also interrupts data transmissions thus degrading the QoS of an ongoing connection. Reducing unnecessary scanning is an important issue. This thesis proposes a scheme to reduce the number of BSs to scan, thus improving the overall handover performance. Simulation results show that the proposed hybrid predictive BS selection scheme for potential scanning activities is more effective than the conventional IEEE 802.16e handover scheme in terms of handover delay and resource wastage. Before the actual handover process, there is scope of reducing the total number of iterations of message exchanges occurring between the mobile MSS, the SBS and the neighbouring BSs which are potential targets for handover. Simulations prove that it takes upto 700 ms to decide the target BS before initiating the handover process with it. There are multiple message exchanges to choose a set of potential target BSs from all the neighbouring BSs. A few more messages flow between the MSS, SBS and potential target BSs to choose the best candidate BS for handover. The many stages and messages waste time and could be reduced. This thesis discusses some ways to reduce them and backs it up with simulation results.
6
Wong, Ka Wai. "A comparative study and novel heuristic approach for the IEEE 802.16e mobile WiMAX power saving mechanism /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?ECED%202009%20WONG.
Повний текст джерела
7
Bose, Biswojit. "Bit error rate estimation in WiMAX communications at vehicular speeds using Nakagami-m fading model." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2013. https://ro.ecu.edu.au/theses/530.
Повний текст джерелаАнотація:
The wireless communication industry has experienced a rapid technological evolution from its basic first generation (1G) wireless systems to the latest fourth generation (4G) wireless broadband systems. Wireless broadband systems are becoming increasingly popular with consumers and the technological strength of 4G has played a major role behind the success of wireless broadband systems. The IEEE 802.16m standard of the Worldwide Interoperability for Microwave Access (WiMAX) has been accepted as a 4G standard by the Institute of Electrical and Electronics Engineers in 2011. The IEEE 802.16m is fully optimised for wireless communications in fixed environments and can deliver very high throughput and excellent quality of service. In mobile communication environments however, WiMAX consumers experience a graceful degradation of service as a direct function of vehicular speeds. At high vehicular speeds, the throughput drops in WiMAX systems and unless proactive measures such as forward error control and packet size optimisation are adopted and properly adjusted, many applications cannot be facilitated at high vehicular speeds in WiMAX communications. For any proactive measure, bit error rate estimation as a function of vehicular speed, serves as a useful tool. In this thesis, we present an analytical model for bit error rate estimation in WiMAX communications using the Nakagami-m fading model. We also show, through an analysis of the data collected from a practical WiMAX system, that the Nakagami-m model can be made adaptive as a function of speed, to represent fading in fixed environments as well as mobile environments.
8
Mojela, Lerotholi Solomon. "On the use of WiMAX and Wi-Fi in a VANET to provide in-vehicle connectivity and media distribution." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17881.
Повний текст джерелаАнотація:
Thesis (MScEng)--Stellenbosch University, 2011.ENGLISH ABSTRACT: The recent emergence of ubiquitous wireless connectivity and the increasing computational capacity of modern vehicles have triggered immense interest in the possibilities of vehicular connectivity. A plethora of potential applications for vehicular networks have been proposed in the areas of safety, traffic infrastructure management, information, and entertainment. The broad range of applications requires creative utilisation of the available wireless medium, using a combination of existing and novel wireless technologies. In this research the evaluation of one such configuration is performed. Dedicated short range communication for safety applications is assumed, and the use of Wi- Fi and WiMAX for non-safety applications is evaluated. Little is known about the media streaming performance of these wireless technologies in realistic vehicular ad-hoc network (VANET) scenarios. Due to the extreme mobility and unpredictable environmental aspects in a real road environment, an empirical evaluation is performed and presented. Evaluation of a multi-vehicle to infrastructure (V2V2I) VANET, using Wi-Fi for the vehicle-to-vehicle communication and WiMAX for the vehicle to infrastructure (V2I) communication is experimented. It is observed that Wi-Fi is unaffected by the vehicle speed; whenever nodes are within communication range, data gets transferred normally. A detailed characterisation of the network architecture is presented and the results show that a multitude of applications can be supported with this proposed network architecture.
AFRIKAANSE OPSOMMING: Die toenemende beskikbaarheid en digtheid van koordlose netwerke en die verhoogde verwerkingsvermoëns van moderne voertuie het die afgelope paar jaar aansienlike belangstelling gewek in die moontlikhede wat voertuig-kommunikasie bied. ʼn Magdom moontlike toepassings is voorgestel in ʼn wye verskeidenheid van velde insluitende veiligheid, verkeersinfrastruktuur, informasie en vermaak. Hierdie voorstelle vereis die kreatiewe benutting van die beskikbare en nuwe koordlose tegnologieë. Hierdie tesis evalueer een voorbeeld van so ‘n opstelling. ʼn Toegewyde kortafstand kommunikasie modus vir veiligheidstoepassings word aangeneem, terwyl Wi-Fi en WiMAX vir ander toepassings evalueer word. Daar is min navorsing oor die kapasiteit en seinsterkte van hierdie beskikbare netwerke onder realistiese voertuig netwerk (VANET) scenario‘s. Weens die hoë mobiliteit van voertuie en ook die onvoorspelbaarheid van hierdie omgewing word ʼn empiriese evaluasie beskou as die mees gepaste metode. Die navorsing ondersoek ʼn multi-voertuig-totinfrastruktuur- netwerk wat Wi-Fi gebruik vir voertuig-tot-voertuig (V2V) kommunikasie en WiMAX vir voertuig-tot-infrastruktuur (V2I) kommunikasie. Die navorsing bevind dat Wi-Fi nie beïnvloed word deur die spoed van die voertuig nie: wanneer die nodes binne die bereik is van die netwerk word data normaal oorgedra. ‗n Gedetailleerde karakterisering van dié netwerk word gedoen en die resultate dui aan dat ‗n groot hoeveelheid toepassings ondersteun kan word deur dié opstelling.
9
Salah, Adham M. S. "Investigation of Integrated Decoupling Methods for MIMO Antenna Systems. Design, Modelling and Implementation of MIMO Antenna Systems for Different Spectrum Applications with High Port-to-Port Isolation Using Different Decoupling Techniques." Thesis, University of Bradford, 2019. http://hdl.handle.net/10454/18427.
Повний текст джерелаАнотація:
Multiple-Input-Multiple-Output (MIMO) antenna technology refers to an antenna with
multiple radiators at both transmitter and receiver ends. It is designed to increase the data rate in
wireless communication systems by achieving multiple channels occupying the same bandwidth
in a multipath environment. The main drawback associated with this technology is the coupling
between the radiating elements. A MIMO antenna system merely acts as an antenna array if the
coupling between the radiating elements is high. For this reason, strong decoupling between the
radiating elements should be achieved, in order to utilize the benefits of MIMO technology.
The main objectives of this thesis are to investigate and implement several printed MIMO
antenna geometries with integrated decoupling approaches for WLAN, WiMAX, and 5G
applications. The characteristics of MIMO antenna performance have been reported in terms of
scattering parameters, envelope correlation coefficient (ECC), total active reflection coefficient
(TARC), channel capacity loss (CCL), diversity gain (DG), antenna efficiency, antenna peak gain
and antenna radiation patterns.
Three new 2×2 MIMO array antennas are proposed, covering dual and multiple spectrum
bandwidths for WLAN (2.4/5.2/5.8 GHz) and WiMAX (3.5 GHz) applications. These designs
employ a combination of DGS and neutralization line methods to reduce the coupling caused by
the surface current in the ground plane and between the radiating antenna elements. The minimum
achieved isolation between the MIMO antennas is found to be better than 15 dB and in some
bands exceeds 30 dB. The matching impedance is improved and the correlation coefficient values
achieved for all three antennas are very low. In addition, the diversity gains over all spectrum
bands are very close to the ideal value (DG = 10 dB).
The forth proposed MIMO antenna is a compact dual-band MIMO antenna operating at
WLAN bands (2.4/5.2/5.8 GHz). The antenna structure consists of two concentric double square
rings radiating elements printed symmetrically. A new method is applied which combines the
defected ground structure (DGS) decoupling method with five parasitic elements to reduce the
coupling between the radiating antennas in the two required bands.
A metamaterial-based isolation enhancement structure is investigated in the fifth proposed
MIMO antenna design. This MIMO antenna consists of two dual-band arc-shaped radiating
elements working in WLAN and Sub-6 GHz 5th generation (5G) bands. The antenna placement
and orientation decoupling method is applied to improve the isolation in the second band while
four split-ring resonators (SRRs) are added between the radiating elements to enhance the
isolation in the first band.
All the designs presented in this thesis have been fabricated and measured, with the simulated
and measured results agreeing well in most cases.Higher Committee for Education Development in Iraq (HCED)
10
Diameh, Yousef A. "The optimization of multiple antenna broadband wireless communications. A study of propagation, space-time coding and spatial envelope correlation in Multiple Input, Multiple Output radio systems." Thesis, University of Bradford, 2013. http://hdl.handle.net/10454/6361.
Повний текст джерелаАнотація:
This work concentrates on the application of diversity techniques and space time block coding for future mobile wireless communications.
The initial system analysis employs a space-time coded OFDM transmitter over a multipath Rayleigh channel, and a receiver which uses a selection combining diversity technique. The performance of this combined scenario is characterised in terms of the bit error rate and throughput. A novel four element QOSTBC scheme is introduced, it is created by reforming the detection matrix of the original QOSTBC scheme, for which an orthogonal channel matrix is derived. This results in a computationally less complex linear decoding scheme as compared with the original QOSTBC. Space time coding schemes for three, four and eight transmitters were also derived using a Hadamard matrix.
The practical optimization of multi-antenna networks is studied for realistic indoor and mixed propagation scenarios. The starting point is a detailed analysis of the throughput and field strength distributions for a commercial dual band 802.11n MIMO radio operating indoors in a variety of line of sight and non-line of sight scenarios. The physical model of the space is based on architectural schematics, and realistic propagation data for the construction materials. The modelling is then extended and generalized to a multi-storey indoor environment, and a large mixed site for indoor and outdoor channels based on the Bradford University campus.
The implications for the physical layer are also explored through the specification of antenna envelope correlation coefficients. Initially this is for an antenna module configuration with two independent antennas in close proximity. An operational method is proposed using the scattering parameters of the system and which incorporates the intrinsic power losses of the radiating elements. The method is extended to estimate the envelope correlation coefficient for any two elements in a general (N,N) MIMO antenna array. Three examples are presented to validate this technique, and very close agreement is shown to exist between this method and the full electromagnetic analysis using the far field antenna radiation patterns.
11
Dia'meh, Yousef Ali. "The optimization of multiple antenna broadband wireless communications : a study of propagation, space-time coding and spatial envelope correlation in Multiple Input, Multiple Output radio systems." Thesis, University of Bradford, 2013. http://hdl.handle.net/10454/6361.
Повний текст джерелаАнотація:
This work concentrates on the application of diversity techniques and space time block coding for future mobile wireless communications. The initial system analysis employs a space-time coded OFDM transmitter over a multipath Rayleigh channel, and a receiver which uses a selection combining diversity technique. The performance of this combined scenario is characterised in terms of the bit error rate and throughput. A novel four element QOSTBC scheme is introduced, it is created by reforming the detection matrix of the original QOSTBC scheme, for which an orthogonal channel matrix is derived. This results in a computationally less complex linear decoding scheme as compared with the original QOSTBC. Space time coding schemes for three, four and eight transmitters were also derived using a Hadamard matrix. The practical optimization of multi-antenna networks is studied for realistic indoor and mixed propagation scenarios. The starting point is a detailed analysis of the throughput and field strength distributions for a commercial dual band 802.11n MIMO radio operating indoors in a variety of line of sight and non-line of sight scenarios. The physical model of the space is based on architectural schematics, and realistic propagation data for the construction materials. The modelling is then extended and generalized to a multi-storey indoor environment, and a large mixed site for indoor and outdoor channels based on the Bradford University campus. The implications for the physical layer are also explored through the specification of antenna envelope correlation coefficients. Initially this is for an antenna module configuration with two independent antennas in close proximity. An operational method is proposed using the scattering parameters of the system and which incorporates the intrinsic power losses of the radiating elements. The method is extended to estimate the envelope correlation coefficient for any two elements in a general (N,N) MIMO antenna array. Three examples are presented to validate this technique, and very close agreement is shown to exist between this method and the full electromagnetic analysis using the far field antenna radiation patterns.
12
Hussaini, Abubakar Sadiq. "Energy efficient radio frequency system design for mobile WiMax applications : modelling, optimisation and measurement of radio frequency power amplifier covering WiMax bandwidth based on the combination of class AB, class B, and C operations." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5749.
Повний текст джерелаАнотація:
In today's digital world, information and communication technology accounts for 3% and 2% of the global power consumption and CO2 emissions respectively. This alarming figure is on an upward trend, as future telecommunications systems and handsets will become even more power hungry since new services with higher bandwidth requirements emerge as part of the so called 'future internet' paradigm. In addition, the mobile handset industry is tightly coupled to the consumer need for more sophisticated handsets with greater battery lifetime. If we cannot make any significant step to reducing the energy gap between the power hungry requirements of future handsets, and what battery technology can deliver, then market penetration for 4G handsets can be at risk. Therefore, energy conservation must be a design objective at the forefront of any system design from the network layer, to the physical and the microelectronic counterparts. In fact, the energy distribution of a handset device is dominated by the energy consumption of the RF hardware, and in particular the power amplifier design. Power amplifier design is a traditional topic that addresses the design challenge of how to obtain a trade-off between linearity and efficiency in order to avoid the introduction of signal distortion, whilst making best use of the available power resources for amplification. However, the present work goes beyond this by investigating a new line of amplifiers that address the green initiatives, namely green power amplifiers. This research work explores how to use the Doherty technique to promote efficiency enhancement and thus energy saving. Five different topologies of RF power amplifiers have been designed with custom-made signal splitters. The design core of the Doherty technique is based on the combination of a class B, class AB and a class C power amplifier working in synergy; which includes 90-degree 2-way power splitter at the input, quarter wavelength transformer at the output, and a new output power combiner. The frequency range for the amplifiers was designed to operate in the 3.4 - 3.6 GHz frequency band of Europe mobile WiMAX. The experimental results show that 30dBm output power can be achieved with 67% power added efficiency (PAE) for the user terminal, and 45dBm with 66% power added efficiency (PAE) for base stations which marks a 14% and 11% respective improvement over current stateof- the-art, while meeting the power output requirements for mobile WiMAX applications.
13
Hussaini, Abubakar S. "Energy efficient radio frequency system design for mobile WiMax applications. Modelling, optimisation and measurement of radio frequency power amplifier covering WiMax bandwidth based on the combination of class AB, class B, and C operations." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5749.
Повний текст джерелаАнотація:
In today´s digital world, information and communication technology accounts for 3%
and 2% of the global power consumption and CO2 emissions respectively. This
alarming figure is on an upward trend, as future telecommunications systems and
handsets will become even more power hungry since new services with higher
bandwidth requirements emerge as part of the so called ¿future internet¿ paradigm. In
addition, the mobile handset industry is tightly coupled to the consumer need for more
sophisticated handsets with greater battery lifetime. If we cannot make any significant
step to reducing the energy gap between the power hungry requirements of future
handsets, and what battery technology can deliver, then market penetration for 4G
handsets can be at risk. Therefore, energy conservation must be a design objective at the
forefront of any system design from the network layer, to the physical and the
microelectronic counterparts. In fact, the energy distribution of a handset device is
dominated by the energy consumption of the RF hardware, and in particular the power
amplifier design. Power amplifier design is a traditional topic that addresses the design
challenge of how to obtain a trade-off between linearity and efficiency in order to avoid
the introduction of signal distortion, whilst making best use of the available power
resources for amplification. However, the present work goes beyond this by
investigating a new line of amplifiers that address the green initiatives, namely green
power amplifiers. This research work explores how to use the Doherty technique to
promote efficiency enhancement and thus energy saving. Five different topologies of
RF power amplifiers have been designed with custom-made signal splitters. The design
core of the Doherty technique is based on the combination of a class B, class AB and a
class C power amplifier working in synergy; which includes 90-degree 2-way power
splitter at the input, quarter wavelength transformer at the output, and a new output
power combiner. The frequency range for the amplifiers was designed to operate in the
3.4 - 3.6 GHz frequency band of Europe mobile WiMAX. The experimental results
show that 30dBm output power can be achieved with 67% power added efficiency
(PAE) for the user terminal, and 45dBm with 66% power added efficiency (PAE) for
base stations which marks a 14% and 11% respective improvement over current stateof-
the-art, while meeting the power output requirements for mobile WiMAX
applications.
14
VERMA, PANKAJ. "PERFORMANCE ANALYSIS OF FIXED AND MOBILE WIMAX SYSTEMS." Thesis, 2011. http://dspace.dtu.ac.in:8080/jspui/handle/repository/17556.
Повний текст джерелаАнотація:
The common feature of the next generation of wireless communications technologies (or 4G ) will be the convergence of different wireless networks with multimedia services such as speech, audio, video, image, Internet services, and data at high data rates and with high mobility, high capacity and high QoS. There are many techniques that fulfill these requirements. One of the most important technique is Orthogonal Frequency Division Multiplexing (OFDM) . OFDM has recently gained a lot of attention and is a potential candidate for 4G wireless systems because it promises data rates up to one Gbps or less under stationary conditions and up to about 100 Mbps under vehicular conditions and it has robustness against multipath fading channels effects. A variation of OFDM is Multi-Carrier Code Division Multiple Access (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. WiMAX (Worldwide Interoperability for Microwave Access) is OFDM-based technology that supports point to multi-point (PMP) Broadband Wireless Access (BWA) for the next generation radio access. Main application (fixed and mobile) of WiMAX today is for MAN/WAN base stations and link stations. It delivers the maximum range (50 km) and higher data rates (up to 75 Mbps) than Wi-Fi. WiMAX has been implemented depending on IEEE 802.16 standard which was designed by Institute of Electrical and Electronic Engineers (IEEE). This thesis aims to analyze and simulate a MC-CDMA system to be used in WiMAX instead of OFDM system. A MATLAB code had been written to simulate both Fixed WiMAX (IEEE 802.16d) and Mobile WiMAX (IEEE 802.16e). The analysis part includes a comparison between them in performance evaluation. The simulation results include the performance analysis based on bit error rate (BER) versus bit energy to noise rate (Eb/No ) plots and spectral efficiency of different modulation and channel coding schemes according to the standard IEEE 802.16. The results show that MC-CDMA outperforms OFDM in WiMAX system and enhances the performance more when spreading factor increases.
15
Chen, Shi-Chi, and 陳錫祺. "Pilot-Assisted Iterative Channel Estimation for Mobile WiMAX Systems." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/89446077550038051710.
Повний текст джерелаАнотація:
碩士國立交通大學
電子工程系所
95
Orthogonal Frequency Division Multiplexing (OFDM) is a popular technique in modern wireless communications. There are many systems adopting the OFDM technique, such as IEEE 802.11 a/g/n, IEEE 802.16, IEEE 802.20, and Digital Video Broadcasting, etc. On the other hand, mobility is an important issue that needs to be taken into account in the design of future wireless communication systems. For example, IEEE 802.16-2005 supports vehicle speed up to 120 km/hr, and IEEE 802.20 supports vehicle speed up to 250 km/hr, causing the channel seen by the receiver time-varying. Some channel estimators use a large number of pilot symbols to estimate the channel parameters, or use buffer to obtain desired channel parameters. In this thesis, we show two channel estimation approaches, namely the decision directed based and expectation maximization based approaches that can track the time-varying channel vectors with less insertion of pilot symbols. Finally, we evaluate the performance of the proposed systems under mobility using IEEE 802.16-2005 standard and confirm that it achieves good SER performance.
16
Tsai, Chia-Hang, and 蔡嘉航. "Iterative Channel Estimation and ICI Cancellation for Mobile WiMAX Systems." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/g38wu6.
Повний текст джерелаАнотація:
碩士國立交通大學
電信工程系所
95
Orthogonal Frequency Division Multiplexing (OFDM) is a popular technique in modern wireless communications. There are many systems adopting the OFDM technique, such as IEEE 802.11 a/g/n, IEEE 802.16, Digital Video Broadcasting, etc. On the other hand, mobile transmission is a trend in future wireless communications. For example, IEEE 802.16-2005 supports vehicle speed up to 120 km/hour. OFDM systems can be used efficiently in time invariant environments with one-tap equalizers. However, subcarriers are no longer orthogonal to each other in time-varying channels, and this causes the intercarrier interference (ICI) and degrades the system performance. To alleviate this problem, we propose an iterative ICI mitigation and time-varying channel estimation scheme, which can obtain the ICI information from the channel estimate using piece-wise linear or Taylor series approximate and then cancel it in parallel fashion. The proposed PIC structure and the overall iterative system structure designed are discussed in detail. Finally, we evaluate the performance of the proposed system under mobility using IEEE 802.16-2005 standard and confirm that it achieves good BER performance.
17
Ho, Meng-Heng, and 何孟衡. "Iterative Channel Estimation and Soft Decoding in Mobile WiMAX systems." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/j237p8.
Повний текст джерелаАнотація:
碩士國立臺北科技大學
電腦與通訊研究所
98
This thesis use standard IEEE 802.16e-2005 to make platform for simulating decoded performance when Mobile WiMAX Down Link system under the channel has velocity. While wireless transmission, WiMAX signal will be disturbed by a lot unknowable noise and multi-path. For receiving correct data, we need using channel estimation to offset channel fading and then get original data by decoder. The platform use channel model is established by ITU-R. This thesis compare the decoded performances, which are simulated by using QPSK, 16QAM, 64QAM under different velocity channels and offset by two Dimensional linear interpolation or iterative channel estimation.
18
Chen, Liang-Chun, and 陳亮均. "Scheduling Mechanisms of Interleaved-Sleep-Listen for Mobile WiMAX Communication Systems." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/17552327514559539855.
Повний текст джерелаАнотація:
博士國立臺灣科技大學
資訊管理系
101
In broadband wireless access (BWA) networks, the power consumption of the mobile devices can be saved by allowing the nodes to enter the sleep mode when they are not transmitting or receiving data. IEEE 802.16e standard has defined three power-saving classes (PSCs) according to the sleep modes. However, the power-saving efficiency is not acceptable because the sleep windows of multiple connections are not overlapping when these connections coexist in a mobile station (MS). Therefore, this dissertation proposes an Interleaved-Sleep-Listen (ISL) algorithm, which synchronizes the overlapping sleep windows with interleaving scheduling to obtain the maximum unavailability interval (MUI). The simulation results show that ISL improves the power-saving efficiency under the condition of multiple connections existing in a MS. The sleep/listen windows must be scheduled by the base station (BS) in unit of an Orthogonal Frequency Division Multiplexing (OFDM) frame. If the radio resources are insufficient, the BS can not allocate enough slots for the packets that should be transmitted in an OFDM frame to a MS. Therefore, this dissertation further proposes a method - Interleaved-Sleep-Listen with Collision Avoidance (ISL/CA) algorithm. This method addresses both resource allocation and power-saving efficiency in IEEE 802.16e networks. ISL/CA allocates latter OFDM slots to satisfy the packets whose required bandwidth is larger than the capacity of an OFDM frame and synchronizes the overlapping sleep windows with interleaving scheduling to reduce the power consumption of the mobile station. Simulation results show that the superior performance of ISL/CA and improves the power-saving efficiency, compared with the previous algorithms, in the condition of multiple connections existing in a MS.
19
Chang, Su-Hao, and 張書豪. "Design of Multi-Rate LDPC Decoder for Mobile WiMAX Communication Systems." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/01732083621012500668.
Повний текст джерелаАнотація:
碩士國立清華大學
通訊工程研究所
95
Low-density parity-check codes were first introduced by Robert Gallager in the early 60’s. They are linear block codes which have sparse parity check matrices and provide performance that comes quite close to the Shannon limit. With the advanced technology, implementing LDPC code decoder is not an impossible thing and there are more and more researches on LDPC codes. There are also many communication systems adopt LDPC codes as their channel coding, such as 802.11n and 802.16e. Although LDPC codes have excellent decoding performance, realizing it is never an easy job. There still exist many challenges when implementing LDPC code decoder. The high routing complexity, large chip area and high power consumption all need to take into concerns. In this thesis, we present architecture design, functional simulations and the comparison of decoding performance using different decoding algorithms for IEEE 802.16e LDPC decoder. We will find that there is a trade off between error-correction capability and hardware complexity. The most suitable decoding algorithm “Layered Belief Propagation Algorithm” with min-sum is chosen to implement. The proposed LDPC decoder is implemented by SystemC to do the data flow simulation and use Synopsys Design Compiler to help us to find the critical path. The timing information of Design Complier is then used to estimate the throughput. We use three design techniques in our LDPC decoder: 1. Reconfigurable architecture for all kinds of code rates in 802.16e, 2. Use Benes network to solve routing problem between bit nodes and check nodes, 3. Reorder the model matrix when choosing specific code rates.
20
Abimbola, Idris Adedapo. "Raptor codes-based enhancement of the mobile WiMAX physical layer." 2013. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001376.
Повний текст джерелаАнотація:
M. Tech. Electrical Engineering.Discusses raptor codes as fundamentally designed for erasure control coding technique, however, the overall objective of this dissertation is to examine their efficacy as a forward error correcting code as well as their spectral efficiency in the IEEE 802.16e-2005 physical layer. The specific objectives include: to analyse the error performance of raptor codes in mobile WiMAX ; to investigate the error performance of the various LDPC code classes defined in the mobile WiMAX standard ; to compare the performance of raptor codes and LDPC codes over the Additive White Gaussian Noise (AWGN) channel and to compare the spectral efficiency of raptor codes with that of the LDPC codes.
21
Chien, Yu-Cheng, and 簡銪呈. "HARQ Mechanism with Incremental Redundancy Tail-Biting Convolutional Code in Mobile WiMAX systems." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/cnjvs7.
Повний текст джерелаАнотація:
碩士國立臺北科技大學
電腦與通訊研究所
99
This paper investigates the IEEE802.16e-2009 standard in the downlink, the use of the incremental redundancy tail-biting convolutional codes（TBCC）in HARQ mechanism. In IEEE802.16e standard, when transmission of require higher quality information, we can use hybrid automatic repeat request（HARQ）mechanism to transmit information. This mechanism is a combination of forward error correction（FEC）and automatic repeat request（ARQ）technology, the concept is that using a packet transmitted fail kept the information to improve the correctness of re-transmitted packets, to increase system performance. This paper is simulating different modulation and code rate of retransmission mechanism, and find out best HARQ transmission strategy.
22
Sun, Yi-Wei, and 孫易緯. "The Design of QoS Mechanisms in Mobile WiMAX Network Systems with Handover Procedures." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/8x685w.
Повний текст джерелаАнотація:
碩士國立臺北科技大學
資訊工程系研究所
97
With the ever growing of the multimedia applications, it has become more and more difficult to satisfy the individual Quality of Service (QoS) requirement demanded by each type of multimedia service. To provide the mobility capacity and enlarge the coverage area which the WiFi networks are poor of, Wireless Metropolitan Network (WMAN) technology has been proposed and gained wide attention over the past few years. Among WMAN, Worldwide Interoperability for Microwave Access (WiMAX) system, which is able to support the guaranteed QoS requirement of real-time data and provide mobility support, is poised to become a major player in the WMAN technology. This research works aim to design the QoS mechanisms for mobile WiMAX systems. We combine admission control, packet classifier, bandwidth allocation and packet scheduling to design the QoS simulation platform for such a WiMAX system. We propose a fair and dynamic bandwidth allocation mechanism, which contains two functions of bandwidth allocation and packet scheduling simultaneously. We also design the handover mechanism according to the general handover procedure specified by the IEEE802.16e-2005 standard. Finally, performance evaluations via simulations are conducted to assess the system performance for the network with or without handover procedures employed. It is found that the transmission quality is subject to the modulation rate change significantly in the mobile environments. The proposed bandwidth allocation and handover mechanisms are shown to reduce connection blocking rate and packet dropping rate effectively to enhance WiMAX system efficiency.
23
Daya, Ronak. "Virtual network traffic shaping (VNTS) technique to ensure fairness in virtual WiMax networks." 2009. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.000051805.
Повний текст джерела
24
Su, Wei-Chun, and 蘇薇君. "A Low-Power Multi-mode Programmable-Bandwidth Filter for Mobile WiMAX Wireless Communication Systems." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/93691577196377142235.
Повний текст джерелаАнотація:
碩士國立中正大學
電機工程所
98
A transconductance programmable Operational Transconductance Amplifier (OTA) for multi-mode channel-selection filter is proposed and analyzed. The Gm–programmable OTA is developed using an input stage array which consist of 31 identical input stages. The OTA linearization technique is based on the architecture of two unsymmetrical differential pairs. As a result, the OTA keeps high linearity over a wide transconductance tuning range. The OTA is used to design a third-order elliptic lowpass filter for mobile WiMAX wireless communication systems. The cutoff frequency of the filter is tunable from 1.25MHz to 38.75MHz, Gm tuning ratio is 31 times. SPICE simulations show that the total harmonic distortion (THD) at 500mVpp and filter bandwidth tuning range from 1.25MHz to 20MHz is less than 1%, the power consumption is 1.89~3.34 mW over the tuning range in a TSMC 0.18-μm CMOS process with a single +1.5 V power supply.
25
Alatise, Mary Bosede. "Design and comparative evaluation of handover schemes in mobile wimax networks." 2013. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000208.
Повний текст джерелаАнотація:
M. Tech. Electrical Engineering.Proposes certain approaches aimed at improving handover from the users point of view, the benefits may include enhanced quality of service, avoidance of handover disruption and reduction of handover rate, irrespective of high traffic loads at the BSs.The proposed scheme improves the network performance by minimising the handover delay time and also enhancing the effective use of radio resources
26
Hussaini, Abubakar S., B. A. L. Gwandu, Raed A. Abd-Alhameed, and Jonathan Rodriguez. "Design of Power Efficient Power Amplifier for B3G Base Stations." 2010. http://hdl.handle.net/10454/4793.
Повний текст джерелаАнотація:
yesFourth generation systems require the use of both amplitude and phase modulation to efficiently utilize the available spectrum and to obtain high data rates, hence imposing stringent requirements on the power amplifier in terms of efficiency and linearity and requires the power amplifier to operate linearly and efficiently. The B3G base station transceiver Doherty power amplifier was designed to operate over the frequency range of 3.47GHz to 3.53GHz mobile WiMAX band using Freescale¿s N-Channel Enhancement-Mode Lateral MOSFET Transistor, MRF7S38010HR3; The performances of the Doherty amplifier are compared with that of the conventional Class AB amplifier. The results of 43 dBm output power and 66% power added efficiency are achieved.
27
Lee, Bo-Wei, and 李伯偉. "WiMAX Mobile Consultative System." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/01357962303511394392.
Повний текст джерелаАнотація:
碩士國立高雄第一科技大學
資訊管理所
97
In recent years the campus security incident emerged one after another incessantly, in the television news page layout saw frequently the student had the community in the campus to fight, the self-injury or to injure other people and so on the calamity occurrence, these possibly came from the family uncoordinated problem perhaps cause student''s behavior deviation because of the schoolwork and the sentimental factor, it was unable in the situation which forewarned to injure others also to injure itself. The campus problem so forth occurs unceasingly in the daily life, therefore this research design develop motion psychology consultation system, provides early for student which needs to assist may express with treats at heart pressure pipeline, then cuts the campus accident''s formation rate. This system bracelet general psychology consultation service only defines in the face-to-face consultation and the traditional network consultation fence, but uses the hand-hold running gear consultation, lets the consult user to be possible with consultant anytime and anywhere to carry on the contacting consultation. This system utilizes the WiMax wireless broadband network omnipresent and the high bandwidth characteristic, and matches the GPS localization technology, achieves traces the user’s position, may further carry out the urgent relief operations, but the system design is mainly the student who aims at the Kaohsiung academy provides the service, therefore the use is consults to the student, this system may further expand in the future provides the use which the public figure consults.
28
Ke, Kai-Yuan, and 柯凱元. "Downlink channel estimation for mobile WiMAX system." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/esvym9.
Повний текст джерелаАнотація:
碩士國立臺北科技大學
資訊工程系研究所
98
This thesis studies various channel estimation methods for mobile WiMAX downlink reception. Due to noise, and multi-path interference in the wireless communication environment, the WiMAX signal is faded. Therefore we need to perform the channel estimation to estimate the channel response, and then to compensate for its influence. The thesis uses the physical layer of the IEEE 802.16e-2005 standard as the transmission technique under study. The simulation of the experiments are carried out using software. The channel environment for the experiments is adopted from ITU-R 3GVA and 3GVB models. The thesis studies the relative performance, in terms of BER, for the following channel estimation methods: one-dimensional linear interpolation, two-dimensional linear interpolation, two-dimensional cubic-spline interpolation, maximum likelihood estimator, linear minimum mean square error (LMMSE), minimum mean square error interpolation, time domain MMSE … and so on. Throughout the experimental results we find that two-dimensional linear interpolation is more suitable than other methods in mobile WiMAX downlink system. One possible method to obtain better estimation performance is to perform filtering on all interpolated subcarrier response through FFT and IFFT, which is optimal in the sense of maximum likelihood (ML). For practical applications requiring low complexity algorithm, 2-D linear interpolation is good choice.
29
Lin, MengShiang, and 林盟翔. "Radio Resource Management in Mobile WiMAX System." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/30783414824348759056.
Повний текст джерелаАнотація:
碩士國立交通大學
電子工程系所
94
With the increasing demand in high-speed wireless transmission, the mobile WiMAX based on IEEE 802.16e standard has been adopted as one of the candidates for beyond 3G cellular technologies. In this thesis, to effectively support real-time and non-real-time services, the system performance of mobile WiMAX with different radio resource managements in scheduler controls and the admission control criterion will be evaluated and analyzed. We also observe the effect and interaction with and without hierarchy scheduling in the mixed traffic. Furthermore, the impacts from different frequency reuse factors will also be investigated. The simulation platform, based on mobile WiMAX, is developed to quantify the mobile WiMAX performance. We also establish the MAC layer with basic resource management in this mobile WiMAX platform. The analytic results show the scheduling control, considered the channel condition and OFDMA permutation, can still offer a good performance in single frequency cell coverage and using hierarchy and appropriate scheduling controls can improve the system capacity with QoS guaranteed in a mixed traffic.
30
朱家弘. "Radio Resource Management for Mobile Multihop Relay(MMR) in Mobile WiMAX System." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/96303384716464637895.
Повний текст джерелаАнотація:
碩士國立交通大學
電機學院微電子奈米科技產業專班
97
The mobile WiMAX which provide high speed transmission over large area has been adopted as one of the candidates of next generation communication system. But, with higher demand of multi-media application, not only high date rate and high bandwidth is necessary for wireless transmission, but also to consider whole cell average throughput, and coverage extension. Consequently, the Mobile Multihop Relay (MMR) system will be the solutions of future wireless system. Base on those idea the Mobile Multihop Relay (MMR) system were establish in IEEE 802.16j. In this thesis, we apply Mobile Multihop Relay (MMR) system on mobile WiMAX to investigate the system level performance analysis when poor RF condition users are served with relay. Besides support poor users, we also consider the Quality of Service (QoS) requirements of mixed traffic services. As the result, we build a simulation platform for mobile WiMAX with basic Radio Resource Management (RRM) and Mobile Multihop Relay (MMR) enabled MAC layer. We adopt an effective path selection to consider simple scheduling algorithm for QoS guarantee and SINR enhancement for poor users. In the simulation result, the cell average capacity can be increase significantly because of the Mobile Multihop Relay (MMR) can help the partial poor RF user upgrade their AMC. With Mobile Multihop Relay (MMR) system, the SINR is enhanced so that the transmission quality is promoted and increase the system capacity.
31
Hisao, Shi-Pu, and 蕭世璞. "Downlink Performance Analysis of MIMO System in Mobile WiMAX." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/x43332.
Повний текст джерелаАнотація:
碩士國立交通大學
電子工程系所
96
In the thesis, we introduce multiple-input and multiple-output (MIMO) Antenna techniques and how to control multiple antennas in media access control (MAC) layer in mobile WiMAX. We build a simulation platform for mobile WiMAX with basic Radio Resource Management (RRM) and MIMO-enabled MAC layer. We analyze the system performance, including throughput, quality of service (QoS), and system throughput, different scheduling algorithms (round robin (RR), Maximum Carrier to Interference-plus-Noise Ratio (MaxCINR), proportional fair (PF), early deadline first (EDF)) and different traffic types (VOIP, FTP). Furthermore, we discuss system performance in different MIMO techniques (spatial multiplexing and transmit diversity). Finally, we investigate the influence of padding of a burst and attempt to improve performance by adapting a PDU size.
32
Chan, Derli, and 詹德立. "The Study of Cell Planning for Mobile WiMAX System." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/03582364992905652699.
Повний текст джерелаАнотація:
碩士元智大學
通訊工程學系
99
The cell planning could aid the service provider to optimize the base station configuration, the antenna mode and site location selection in order to meet the quality of service, system capacity and service requirements at minimum cost. In this paper, the cell size of 2.5 GHz Mobile WiMAX is estimated from the link budget using COST-231 Hata propagation model and Stanford University Interim (SUI) Erceg model. A combination of COST-231 Hata and SUI Erceg models is presented to predict the propagation path loss of 2.5GHz Mobile WiMAX in urban, suburban, flat-terrain with light tree (rural A), flat-terrain with heavy tree (rural B) and hilly-terrain rural (rural C) environments. The cell sizes for five different terrain areas, three antenna modes and 90% service reliability are estimated through the downlink link budget analysis.
33
Hung-JungKang and 康宏榮. "Boosting System Performance of Mobile WiMAX Networks: Adaptive Network Coding Approach." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/79143836249206936110.
Повний текст джерелаАнотація:
碩士國立成功大學
電腦與通信工程研究所
98
Recently, WiMAX has emerged to facilitate high-bandwidth wireless access for metropolitan areas. Like all wireless networks, packet loss is an important issue in WiMAX networks. Although WiMAX standards have provided a retransmission mechanism to combat the packet loss issue, the incurred overhead is significant. On the other hand, network coding techniques are explored to improve system throughput in lossy wireless networks. However, current network coding schemes may not achieve best performance in mobile WiMAX networks since they cause considerable overhead and typically ignore the fluctuation of channel condition due to user mobility. Accordingly, this thesis investigates the impact of dynamics of channel condition in the physical layer and the overhead caused by network coding in mobile WiMAX networks. An adaptive network coding mechanism is proposed to achieve excellent system throughput and reduce network coding overhead in the present of fluctuation of channel condition. The analysis and simulation results show that the proposed mechanism improves the resource utilization dramatically while reducing the network coding overhead significantly.
34
Tsai, Chin-Feng, and 蔡錦豐. "Design of Phased Antenna Array for WiMAX and 4G Mobile Communication System." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/42898527813480098484.
Повний текст джерелаАнотація:
碩士國立中正大學
電機工程所
96
The switched-beam system is one kind of smart antenna systems, which can switch the beam to the desired signal direction. The surrounding interferences can thus be reduced so that the signal to noise ratio is increased as well. This thesis work focuses on the beamforming circuit designs for switched-beam system. First, two 3.5-GHz Butler Matrices including 4×4 and 8×8 matrix realized by CPW-G medium on single PCB are introduced. The circuits have compact size（37.8×49.4 mm2 for 4×4 case, 8.9×10.3 cm2 for 8×8 case）with nearly 70% size reduction comparing to the conventional microstip-based Butler matrix. It also shows broadband（3-4 GHz）performance. In addition, an enhanced 4×4 Butler Matrix is designed to provide seven kinds of phase distribution instead of four kinds by using multi-port feeding technique. Based on the similar principle, another newly designed 4×4 Butler Matrix integrated with a variable power divider is first proposed in this thesis work. Using variable power divider and multi-port feeding technique, the direction of beams can be swept continuously, which dramatically increase the space multiplexing ability of this phase antenna array.
35
Su, Wei-Cheng, and 蘇威誠. "Internal Wideband Mobile Phone Antenna for UMTS/WLAN/WiMAX Wireless Communication System." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/19162284871847311873.
Повний текст джерелаАнотація:
碩士國立中山大學
電機工程學系研究所
94
In this thesis, the study mainly focuses on the current trends in development of compact multi-media mobile phone and provides a wideband monopole antenna design suitable for application in wireless communicating system in the near future. By utilizing the planar monopole antenna structure, the proposed antenna design is easy to be embedded into the mobile phone. Further, by using a shielding metal cover, we create a zone with low surface current distribution. This effect will reduce the electromagnetic coupling between the antenna and the electronic elements and make it possible to integrate more related elements into the mobile phones. Finally, we use the simulation software to analyze the dielectric effect caused by the casing of mobile phone and human body on the proposed antenna.
36
LI, CHIEH-HSIU, and 李杰修. "The Study of System Capacity Planning for Mobile WiMAX with Channel Adaptation." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/89809337819210105946.
Повний текст джерелаАнотація:
碩士中原大學
電子工程研究所
97
In the recent year, wireless network is growing very fast. Wireless network can provide some application, such as computers transmit data and cell phone sending voice message. In the wireless service, the multimedia application requirements are increased rapidly. The WiMAX technology can take the advantage of high transmission rate and support high moving speed to provide the multimedia services to a large number of mobile subscribers (MS). In addition, the WiMAX technology also includes five types of service to satisfy the demand of huge number of mobile users. However, the wireless bandwidth resource (channel capacity) is limited. If the system want to provide great Quality of Service (QoS) content to a large number of users at the same time, then there must exist a complete management scheme to allocated the radio resource and promote the system resource utilization. However, IEEE 802.16 standard did not explicitly defined the detail of how to allocate radio resource for the five types of services. Consequently, in this paper, we proposed a radio source management scheme which can guarantee the QoS requirements and maximize the system resource utilization. Our research environment considered the OFDMA physical technology to discuss the influence of the QoS when the handoff and transmission mode (TM) even occur. Besides, we exploit adaptive modulation and coding (AMC) technology, system buffer and guard channel scheme to management the radio resource. The numerical results show that the proposed radio resource management scheme not only guaranteed the QoS (New call blocking probability and Call terminating probability) requirements but raised the system resource utilization.
37
Liao, Yen-Pin, and 廖言彬. "Measurement and Analysis of Three Antenna Modes for IEEE802.16e Mobile WiMAX System." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/01160723696285123340.
Повний текст джерелаАнотація:
碩士元智大學
通訊工程學系
98
All telecom operator pursuit the utmost speed in transmission network in terms of the transmission rate and quality of service. More and more governments aggressively promote the broadband and wireless network in order to enhance the international competitive competence. M–Taoyuan is one of Mobile WiMAX networks where MIMO antenna technology is applied. There are two broadband wireless service lines intersect at Taoyuan County government. One line starts at the northbound, Taoyuan railway station, along the provincial highway N-1 toward the southbound, Chungli railway station. The other starts at eastbound, Pader, along the provincial highway N-4 toward westbound, Nankang. M-Taoyuan is an instance of Mobile WiMAX network. The aim of the thesis mainly studies the performance of three different antenna Modes, including Single-Input Single-Output(SISO), Multi-Input Multi-Output(MIMO) and BeamForming(BF), for the base station of the Mobile WiMAX system. The RSSI and CINR of the Mobile WiMAX system using three different antenna modes are measured and analyzed. The advantage and disadvantage among three different antenna modes are compared. Finally, we apply the test results for the base station deployment of the Mobile WiMAX system.
38
Salmon, Brian Paxton. "Optimizing LDPC codes for a mobile WiMAX system with a saturated transmission amplifier." Diss., 2008. http://hdl.handle.net/2263/25369.
Повний текст джерелаАнотація:
In mobile communication, the user’s information is transmitted through a wireless communication link that is subjected to a range of deteriorating effects. The quality of the transmission can be presented by the rate of transfer and the reliability of the received stream. The capacity of the communication link can be reached through the use of channel coding. Channel coding is the method of adding redundant information to the user’s information to mitigate the deteriorating effects of the communication link. Mobile WiMAX is a technology that makes use of orthogonal frequency division multiplexing (OFDM) modulation to transmit information over a wireless communication channel. The OFDM physical layer has a high peak average to power ratio (PAPR) characteristic that saturates the transmitter’s amplifier quite easily when proper backoff is not made in the transmission power. In this dissertation an optimized graph code was used as an alternative solution to improve the system’s performance in the presence of a saturated transmission’s amplifier. The graph code was derived from a degree distribution given by the density evolution algorithm and provided no extra network overhead to implement. The performance analysis resulted in a factor of 10 improvement in the error floor and a coding gain of 1.5 dB. This was all accomplished with impairments provided by the mobile WiMAX standard in the construction of the graph code.Dissertation (MEng)--University of Pretoria, 2009.
Electrical, Electronic and Computer Engineering
unrestricted
39
Chen, Po-Han, and 陳伯翰. "Radio Resource Managements for Spatial Division Multiple Access (SDMA) In Mobile WiMAX System." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/81063331748787993172.
Повний текст джерелаАнотація:
碩士國立交通大學
電子工程系所
96
The mobile WiMAX based on IEEE 802.16e standard which provides high speed transmission over large area has been adopted as one of the candidates of next generation communication systems. But, with higher demand of multi-media application, high date rates and high bandwidth are necessary for wireless transmission. Consequently, the Multiple Input Multiple Output (MIMO) and Adaptive Antenna System (AAS) will be the solutions of future wireless system. In this thesis, we apply Spatial Division Multiple Access (SDMA) mechanism enabled by AAS on mobile WiMAX to investigate the system level performance analysis when poor RF condition users are served with beamforming. Besides support poor users, we also consider the Quality of Service (QoS) requirements of mixed traffic services. As a result, we build a simulation platform for mobile WiMAX with basic Radio Resource Management (RRM) and SDMA-enabled MAC layer. We adopt a simple two stages scheduling algorithm for QoS guarantee and SINR enhancement for poor users. In the simulation result, the cell capacity can be increase significantly because of the reduction of outage probability. With beamforming, the co-channel interference is suppressed and SINR is enhanced under the same power budget so that the transmission quality is promoted. The simulation results also shows that when two stage scheduling algorithm for SDMA is applied, the system performance is still improved significantly under serious co-channel interference.
40
Tian, Yao-Ru, and 田耀儒. "Load Balancing with Cell Breathing to Maximize the System Reward in Mobile WiMAX." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/85343441093426986219.
Повний текст джерелаАнотація:
碩士國立中正大學
資訊工程所
98
With the rapid development in wireless communication technology, a new generation of wireless network based on IEEE 802.16, referred to as WiMAX, has emerged with some attractive advantages, such as higher data transmission rate, native QoS capabilities, long distance coverage area, etc. It is regarded as the standard of wireless metropolitan area networks (WMAN) and a promising solution for last mile access network. Although WiMAX networks can provide different types of service class for different applications according to their requirements, mobile users in some situations will be gathered in some popular BSs. This will make the distribution of traffic load in the network become very uneven, resulting in the overload BS will have high call blocking probability and call dropping probability, which will limit the bandwidth utilization of overall system and the reward earned by the system. This is not acceptable to both the system operator and the users. Therefore, in this thesis, we propose a Markov Decision Process-based (MDP-based) Call Admission Control (CAC) mechanism which is capable of more effective management of system resources and producing higher reward. In Addition, we combine the MDP-based CAC with a directional cell breathing technique to achieve load sharing among BSs. According to the traffic load of BSs, the overloaded BS will shift part of the traffic to neighboring BS which is lightly loaded. As a result, our mechanism can provide better QoS to the MSs and earned reward to the system.
41
Chen, Kuan-yin, and 陳冠穎. "Mobile WiMAX System: A Systematic View on Cross-Layer Design Methodologies and Software Architecture." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/k3k32e.
Повний текст джерелаАнотація:
碩士國立交通大學
電子工程系所
96
In designing novel wireless communications devices, designers are facing a number of challenges such as standard evolution, market timing, system maintenance and even multi-technology integration. Also, as the performance requirement becomes higher, cross-layer operation plays an important role in modern systems. To accomplish various design goals, the MAC layer architecture should be elaborately defined. In this article, we present a modularized MAC architecture and its design guidelines. This architecture is based on a three-plane conceptual model, and enables quick prototyping, easy maintenance, efficient cross-layer signaling and potential multi-technology integration.
42
Chen, You-Lin, and 陳宥霖. "Energy-Efficient Packet Scheduling Algorithms for Real-Time Communications in a Mobile WiMAX System." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/25957119415162642906.
Повний текст джерелаАнотація:
碩士國立交通大學
資訊科學與工程研究所
94
Broadband wireless access systems usually provide flexible sleep-mode operations for mobile stations to conserve their energy during idle or active mode. For example, Mobile WiMAX, i.e. the IEEE 802.16e, offers several power-saving classes that can be associated with different types of network connections to minimize power consumption of mobile subscriber stations (MSSs). Unfortunately, previous studies did not fully utilize the sleep-mode features to save the energy of an MSS with multiple real-time connections, and power consumption of an MSS is not yet optimized. In this work, two energy-efficient packet scheduling algorithms for real-time communications in a Mobile WiMAX system are proposed. The schemes not only guarantee the quality of services (QoSs) of real-time connections but also minimize power consumption of MSSs. Simulation results demonstrate that the proposed schemes outperform the traditional approach.
43
Lin, Shin-Huey, and 林欣慧. "REDUCTION OF OUT-OF-BAND POWER IN MOBILE WIMAX SYSTEM BY USING HYBRID APPROACH." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/05948158689155395738.
Повний текст джерелаАнотація:
碩士大同大學
電機工程學系(所)
99
High out-of-band power is one of the basic problems of orthogonal frequency division multiplexing (OFDM) system. Several approaches are proposed in previous researches. Tail-Tracking, Zero-Forcing, Cancellation Carrier Insertion, Constellation Expansion, and hybrid approaches are some of them. However, as the growing usage of mobile devices, the ability of mobile communication becomes more and more important. Mobile WiMAX is one of the current trends of mobile broadband system. Implement hybrid approaches on mobile WiMAX, propose simulation results and comparisons, and figure out some differences when these approaches applied on a mobile system. For example, implement approaches when TTG exists, uplink and downlink result different caused by different subcarrier permutation. Simplifying the Tail-Tracking computation and proposing simplified Cancellation Carrier Insertion approach are also proposed in this thesis.
44
Tang, Chung-Hsiang, and 黨中祥. "The Research of Peak-To-Average Power Ratio Reduction In Mobile WiMAX System By using Precoding Method." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/26721119484638367346.
Повний текст джерелаАнотація:
碩士大同大學
通訊工程研究所
100
In recent years, Orthogonal Frequency Division Multiplexing technology(OFDM) has been widely used in today's all kinds of wireless communication systems such as WLAN，DVB and WiMAX such as orthogonal frequency division multiplexing is a multi-carrier modulation techniques, with higher the characteristics of data transmission speed and can effectively overcome frequency selective fading channel, but this technology also need to overcome the shortcomings , which has a major drawback is to produce high peak to average power ratio (PAPR) . Reduction the problem of high PAPR for OFDM system can enhance the performance of high power amplifier (HPA) system and reduce the bit error rate (BER). In addition, this also reducing the analog and digital conversion quantization error is able to reduce the design complexity and cost . This thesis we adopt precoding technique in the application of Mobile「Worldwide Interoperability for Microwave Access system」(Mobile WiMAX ) for the reduction of PRPA. The simulation results show that no matter in downstream or upstream, the effect of reduction of PAPR, are higher than that of using discrete Fourier transform(DFT) matrix. As we increase the number of zero sub-carrier that we adopt for precoding, the more you can more effectively reduce the PAPR. But when Pilot sub-carriers are taken together, the result becomes not so significant as that of previous simulation results .
45
Chiu, Che-Lun, and 邱哲綸. "Reduction of Out-of-Band Power in Mobile WiMAX System under FUSC environment by Using Hybrid Approach." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/02960790341389079203.
Повний текст джерелаАнотація:
碩士大同大學
通訊工程研究所
101
With the popularity of internet, the load of wireless communication is gradually increasing. The Mobile Worldwide Interoperability for Microwave Access (Mobile WiMAX) is developed using Orthogonal Frequency Division Multiplexing.The purpose is hoped to increase the used efficiency of communiaction channels, and to solve the over loading problem of wireless communication.However, the WiMAX technique still has some drawbacks which need to be improved. One of those drawbacks is that frequency domain may be out of power band. This paper adopted the concept of the Boundary Smoothing and employed Tail-Tracking Approach, Zero-Forcing Approach, Insertion of Cancellation Carriers Approach and FUSC to solve the dissipation problem of power band in Mobile WiMAX. The simulation experiments show that the proposed solution can improve the dissipation problem of power band. Furthermore, it is found that the different combinations with PUSC down-link have the different results at different positions of Pilot.
46
Chen, Hung-Hsi, and 陳鴻昕. "On the Handoff Performance of the Hybrid IEEE 802.11 Wireless Local Area Networks and IEEE 802.16e Mobile WiMax System." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/26336337233105408096.
Повний текст джерелаАнотація:
碩士國立交通大學
電信工程系所
95
In recent years, the IEEE 802.11 wireless local area networks (WLANs) have become very popular. However, most application scenarios are limited to hot spot areas without handoff. As many real-time application, e.g. voice over IP(VoIP) grow rapidly, one of the burning issues for WLAN is to reduce handoff latency. Furthermore, IEEE 802.16e wireless metropolitan area networks(WMAN) also attract a great deal of attentions. Thus, in the future, we can expect the appearance of the hybrid IEEE 802.11 WLANs and IEEE 802.16e WMANs system. Clearly seamless and smart handoff in this hybrid network will become an increasingly important issue. In this thesis, we first investigate the handoff issue for the IEEE 802.11 WLANs. Some studies have indicated that the latency in searching available channel in neighboring AP dominates handoff latency. Therefore, we develop an analytical model to calculate the channel search latency and its success probability for the IEEE 802.11 WLANs. We find that the number of the probe requests and that of probe responses are two key design parameters influencing handoff channel search time. Thus, we develop a method to determine the optimal numbers of probe request and probe response. The numerical results demonstrate that a system with the optimum probe request and probe response can reduce the effective search time by 30% to 40% compared to the legacy IEEE 802.11 WLANs. As for the handoff issue in the hybrid IEEE 802.11 WLANs and IEEE 802.16e WMANs system, the system which has shortest handoff latency may not have the highest throughput. Thus, we develop a dynamic network selection scheme to determine the connecting system in a new ``WLAN to hybrid WLAN/WiMax’’ handoff scenario, in which we consider both the vertical and horizontal handoffs. The proposed scheme requests the station to wait an additional network selection time ``tw’’ before the selection to maximize the amount of delivered bits during a dwelling time. We formulate an optimization problem to find the maximum network selection time for maximizing the delivered information bits. In addition, we also find the saturation network selection time for optimizing the delivered bits and handoff latency during the dwelling time. From the numerical analysis, in the case with 5~25 stations in target WLAN, the proposed scheme can improve the delivered bits at least by 10% compared to that without awaiting the scenario.
47
Liu, Yu-Nan, and 劉育男. "The Research of Peak-To-Average Power Ratio Reduction In Mobile WiMAX System Under DL FUSC Environment By Using Precoding Method." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/38545946384938860480.
Повний текст джерелаАнотація:
碩士大同大學
通訊工程研究所
102
Due to the popularity of mobile Internet, wireless communications bandwidth causing an increasing load, so the need of mobile worldwide interoperability for microwave access interface standard (Mobile WiMAX) becomes promising. Hence orthogonal frequency division multiplexing technology (OFDM) is developed to increase the efficient usage of bandwidth and high-speed data transmission and this technology is widely used in many wireless communication systems. However, OFDM systems own a major drawback is that will produce high peak to average power ratio (PAPR). Precoding is a decorrelation techniques of data symbol has been proved to be a effective PAPR reduction approach with lower computational complexity in comparison with other researches. Meanwhile pilot subcarriers of OFDM system; used for channel estimation, would reduce the effect of decorrelation of OFDM symbols by DFT matrix or Precoding Matrix and would rise PAPR. This thesis is dedicated to study to reduce the PAPR in the downlink of Mobile WiMAX by using FUSC (Fully Usage of SubChannels) with pilot subcarriers in the preprocessing approach both in DFT matrix and Precoding matrix. Simulation results show that the reduction of PAPR in FUSC is better than that of PUSC (Partially Usage of SubChannels) in the case of the downlink both with preprocess of the DFT matrix and the Precoding Matrix, and the major reason is due to that the total number of pilot carriers used in FUSC is less than that of PUSC.