165 results on '"Multichannel communication -- Methods"'
Search Results
2. On the diversity-multiplexing tradeoff of amplify-and-forward half-duplex relaying
- Author
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Wicaksana, H., Ting, S.H., Motani, M., and Guam, Y.L.
- Subjects
Digital signal processor ,Computer networks -- Research ,Information networks -- Research ,Signal processing -- Methods ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods - Published
- 2010
3. Diversity-multiplexing tradeoff analysis for OFDM systems with subcarrier grouping, linear precoding, and linear detection
- Author
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Prasad, Narayan, Venturino, Luca, and Xiaodong Wang
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Functions, Orthogonal -- Research ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Linear systems -- Research ,Capacity management (Computers) -- Methods - Published
- 2010
4. Simplified maximum-likelihood precoder selection for spatial multiplexing systems
- Author
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Jong-Ho Lee, Sung-Yoon Jung, and Daeyoung Park
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Computational complexity -- Measurement ,Feedback (Electronics) -- Analysis ,Maximum likelihood estimates (Statistics) -- Usage ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Business ,Electronics ,Electronics and electrical industries ,Transportation industry - Published
- 2010
5. Cooperative transmission in a wireless relay network based on flow management
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Chatterjee, Debdeep, Wong, Tan F., and Lok, Tat M.
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Wireless technology ,Mobile communication systems -- Models ,Wireless communication systems -- Models ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods - Published
- 2010
6. Error performance analysis of BPSK modulation in physical-layer network-coded bidirectional relay networks
- Author
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Ju, Minchul and Kim, Il-Min
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Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Error-correcting codes -- Analysis - Published
- 2010
7. Cryogenic fluid level sensors multiplexed by frequency-shifted interferometry
- Author
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Ye, Fei, Chen, Tong, Xu, Di, Chen, Kevin P., Qi, Bing, and Qian, Li
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Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Circuit design -- Methods ,Circuit design -- Technology application ,Interferometry -- Methods ,Sensors -- Design and construction ,Circuit designer ,Integrated circuit design ,Technology application ,Astronomy ,Physics - Abstract
We present a liquid level sensing system for cryogenic fluids based on an array of aluminum-coated fiber Bragg gratings written in high-attenuation fibers (HAFs) interrogated by frequency-shifted interferometry (FSI). The sensors are heated up optically through the absorption of light at the core of the HAF sections. The distinct thermal response of sensors in the liquid from that in the gas provides an unambiguous means to detect the liquid level. FSI allows the sensors to have overlapped spectral response, and, therefore, has the potential of accommodating a larger number of sensors in the array. The measurement of liquid nitrogen level using this system was experimentally demonstrated. The successful combination of aluminum-coated HAF Bragg grating sensors and the FSI technique promises a viable solution for liquid level sensor networks at cryogenic temperatures. OCIS codes: 060.2370, 120.3180, 060.3735, 060.4230.
- Published
- 2010
8. Statistical multiplexing of upstream transmissions in DOCSIS cable networks
- Author
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Heyaime-Duverge, C.C. and Prabhu, V.K.
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Bandwidth -- Measurement ,Cable networks (Television) -- Design and construction ,Computer network protocols -- Analysis ,Computer-generated environments -- Usage ,Computer simulation -- Usage ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Bandwidth allocation ,Bandwidth technology ,Protocol ,Quality of service ,Business ,Electronics ,Mass communications - Published
- 2010
9. Achieving highperformance burst transmission for bursty traffic using optical burst chain switching in WDM networks
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Liu, Yong, Chua, Chaing, and Mohan, Gurusami
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Digital multiplexing -- Methods ,Digital multiplexing -- Research ,Multichannel communication -- Methods ,Multichannel communication -- Research ,Multiplexing -- Methods ,Multiplexing -- Research ,Optical communications -- Usage ,Burst mode -- Methods - Published
- 2010
10. Multiwavelength recording with a random pattern reference scheme
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Inoue, Ai, Takayama, Yoshihisa, and Kodate, Kashiko
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Multichannel communication -- Methods ,Multiplexing -- Methods ,Digital multiplexing -- Methods ,Optics -- Research ,Optics -- Methods ,Astronomy ,Physics - Abstract
In a random-reference multiplexing scheme, we propose a method of generating different wavefronts without rotating a random pattern-generating element, simply by changing the wavelength of the incident light. A reference pattern with a random wavefront is an important aspect of color recording and readout. The color recording and readout system we propose is simple and compact, and generation of uncorrelated color patterns is easy. An important feature is that simultaneous readout using multiple wavelengths is facilitated. We confirmed the feasibility of this system by simulation and experiment, and we examined color recording and readout using multiple wavelengths. [c] 2010 Optical Society of America OCIS codes: 210.2860, 090.4220.
- Published
- 2010
11. Delay-constrained multiplexing of video streams using dual-frame video coding
- Author
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Tiwari, M., Groves, T., and Cosman, P.C.
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Streaming media -- Management ,Image coding -- Usage ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Internet videos -- Distribution ,Streaming media technology ,Company business management ,Company distribution practices ,Business ,Computers ,Electronics ,Electronics and electrical industries - Published
- 2010
12. Synthetic aperture superresolved microscopy in digital lensless Fourier holography by time and angular multiplexing of the object information
- Author
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Granero, Luis, Mico, Vicente, Zalevsky, Zeev, and Garcia, Javier
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Microscope and microscopy -- Methods ,Microscope and microscopy -- Technology application ,Holography -- Equipment and supplies ,Fourier transformations -- Research ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Imaging systems -- Methods ,Imaging systems -- Equipment and supplies ,Imaging systems -- Technology application ,Technology application ,Astronomy ,Physics - Abstract
The resolving power of an imaging system in digital lensless Fourier holographic configuration is mainly limited by the numerical aperture of the experimental setup that is defined by both the restricted CCD size and the presence of a beam splitter cube in front of the CCD. We present a method capable of improving the resolution in such a system configuration based on synthetic aperture (SA) generation by using time-multiplexing tilted illumination onto the input object. Moreover, a priori knowledge about the imaged object allows customized SA shaping by the addition of elementary apertures only in the directions of interest. Experimental results are provided, showing agreement with theoretical predictions and demonstrating a resolution limit corresponding with a synthetic numerical aperture value of 0.45. OCIS codes: 050.1940, 090.1995, 100.2000, 100.6640, 110.0180, 110.1650.
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- 2010
13. Numerical evaluation of angular multiplexing in reflection-type holographic data storage in photopolymer with shrinkage
- Author
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Yonetani, Yusuke, Nitta, Kouichi, and Matoba, Osamu
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Numerical analysis -- Research ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Information storage and retrieval -- Methods ,Information storage and retrieval -- Technology application ,Photopolymers -- Properties ,Technology application ,Astronomy ,Physics - Abstract
We evaluate numerically the effect of shrinkage of photopolymer on the bit error rate or signal-to-noise ratio in a reflection-type holographic data storage system with angular multiplexing. In the evaluation, we use a simple model where the material is divided into layered structures and then the shrinkage rate is proportional to the intensity in each layer. We present the effectiveness of the proposed model from the experimental results in the recording of the plane waves both in a transmission-type hologram and a reflection-type one. Several kinds of shrinkage rates are used to evaluate the characteristics of angular multiplexing in the reflection-type holographic memory. [c] 2010 Optical Society of America OCIS codes: 210.2860, 160.5470, 090.7330.
- Published
- 2010
14. Hologram positioning servo for phase-encoded holographic data storage systems
- Author
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Gorocs, Zoltan, Sarkadi, Tamas, Erdei, Gabor, and Koppa, Pal
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Information storage and retrieval -- Methods ,Information storage and retrieval -- Equipment and supplies ,Information storage and retrieval -- Technology application ,Holography -- Methods ,Digital multiplexing -- Methods ,Digital multiplexing -- Technology application ,Multichannel communication -- Methods ,Multichannel communication -- Technology application ,Multiplexing -- Methods ,Multiplexing -- Technology application ,Technology application ,Astronomy ,Physics - Abstract
We propose a method using phase encryption and hologram multiplexing to encode positional information into the hologram, which can be used during readout to find the correct position of the reference beam. We also include a method to align the position of the phase code in the reference beam during readout, with which we achieved approximately 1/100 hologram size (4.4 [micro]m) precision electronically, without the need of a precise mechanical hologram positioning device. We prove the feasibility of the method with experiments. [c] 2010 Optical Society of America OCIS codes: 090.0090, 090.4220, 210.2860.
- Published
- 2010
15. Fixed-data-rate power minimization algorithm for OFDM-based power-line communication networks
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Marijic, Zdravko, Ilic, Zeljko, and Bazant, Alen
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Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Powerline networks -- Methods ,Powerline networks -- Maintenance and repair ,Algorithms -- Innovations ,Algorithm ,Business ,Computers ,Electronics ,Electronics and electrical industries - Published
- 2010
16. A packet OADMs for the next generation of ring networks
- Author
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Chiaroni, Dominique, Santamaria, Gema Buforn, Simmonneau, Christian, Etienne, Sophie, Antona, Jean-Christophe, Bigo, Sebastien, and Simsarian, Jesse
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Token Ring networks -- Models ,Token Ring networks -- Testing ,Token Ring networks -- Methods ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Packet switching -- Methods ,Fiber optic networks -- Methods ,Token Ring network ,Packet switching technology ,Fiber transmission equipment ,Science and technology ,Telecommunications industry - Abstract
A ring network that exploits optical transparency and packet granularity is presented. This is a solution at the convergence of reconfigurable optical add/drop multiplexer and Ethernet technologies. The feasibility of the network and the actions required to introduce the technology to the marketplace are discussed.
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- 2010
17. Recent advances in submarine optiocal communication systems
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Salsi, Massimiliano, Charlet, Gabriel, Renaudier, Jeremie, BErtran-Pardo, Oriol, Mardoyan, Haik, Bigo, Sebastien, Plantady, Philippe, and Calsat, Alain
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Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Phase modulation -- Methods ,Submarine cables -- Innovations ,Submarine cables -- Testing ,Science and technology ,Telecommunications industry - Abstract
The polarization division multiplexing modulation binary phase shift keying format that has 0.8 bit/s/Hz spectral efficiency is proposed. The performance of this solution is tested on a submarine link and its potential to increase total capacity of submarine systems is demonstrated.
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- 2010
18. 40 Gb/s DBPSK and DQPSK formats for transparent 50 GHz DWDM transmission
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Chandrasekhar, Sethumadhavan and Liu, Xiang
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Broadband transmission -- Testing ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Phase modulation -- Testing ,Phase modulation -- Methods ,Broadband Internet ,Science and technology ,Telecommunications industry - Abstract
The performance of differential binary and quadrature phase shift keying under optical filtering, crosstalk, and polarization mode dispersion are discussed. These two modulation formats are investigated to address the challenges in supporting 40 Gb/s for dense wavelength division multiplexed networks.
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- 2010
19. Dual signal amplification of glucose oxidase-functionalized nanocomposites as a trace label for ultrasensitive simultaneous multiplexed electrochemical detection of tumor markers
- Author
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Lai, Guosong, Yan, Feng, and Ju, Huangxian
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Tumor markers -- Properties ,Electrochemistry -- Research ,Chemical detectors -- Usage ,Chemical detectors -- Technology application ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Composite materials -- Chemical properties ,Composite materials -- Composition ,Composite materials -- Technology application ,Nanotechnology -- Research ,Technology application ,Chemistry - Abstract
A novel tracer, glucose oxidase-functionalized nanocomposite, was designed to label the signal antibodies for ultrasensitive multiplexed measurement of tumor markers using a disposable immunosensor array. The immunosensor array was constructed by coating layer-by-layer colloidal Prussian blue (PB), gold nanoparticles, and capture antibodies on screen-printed carbon electrodes. The preparation of glucose oxidase-functionalized nanocomposites and the labeling of antibody were performed by one-pot assembly of glucose oxidase and antibody on gold nanoparticles attached carbon nanotubes. The PB immobilized on immunosensor surface acted as a mediator to catalyze the reduction of [H.sub.2][O.sub.2] produced in the enzymatic cycle. Both the high-content glucose oxidase and carbon nanotubes in the tracer amplified the detectable signal for the sandwich-type immunoassay. Using carcinoembryonic antigen and [alpha]-fetoprotein as model analytes, the simultaneous multiplexed immunoassay method using the immunosensor array and the designed tracer showed linear ranges of 3 orders of magnitude with the detection limits down to 1.4 and 2.2 pg/mL, respectively. The assay results of serum samples with the proposed method were in an acceptable agreement with the reference values. The dual signal amplification of glucose oxidase-functionalized nanocomposites provided a promising ultrasensitive simultaneous multiplexed immunoassay approach for clinical applications. 10.1021/ac901996a
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- 2009
20. Throughput-based switching between diversity and multiplexing in MIMO systems with cochannel interference
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Wang, Jui Teng
- Subjects
MIMO communications -- Research ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Electromagnetic interference -- Control ,Coding theory -- Research ,Business ,Electronics ,Electronics and electrical industries ,Transportation industry - Published
- 2009
21. Group-mode hopping for collision mitigation in orthogonal code-hopping multiplexing
- Author
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Moon, Sung Ho, Park, Suwon, Kwon, Jae Kyun, Kim, Junsu, and Sung, Dan Keun
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CDMA technology -- Research ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Coding theory -- Research ,Code Division Multiple Access technology ,Business ,Electronics ,Electronics and electrical industries ,Transportation industry - Published
- 2009
22. Two-dimensional planar array for digital beamforming and direction-of-arrival estimations
- Author
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Kim, Shinho and Wang, Yuanxun Ethan
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Multichannel communication -- Methods ,Digital multiplexing -- Methods ,Multiplexing -- Methods ,Mobile communication systems -- Research ,Wireless communication systems -- Research ,Beamforming -- Methods ,Antennas (Electronics) -- Design and construction ,Wireless technology ,Business ,Electronics ,Electronics and electrical industries ,Transportation industry - Published
- 2009
23. Cooperative multiplexing: toward higher spectral efficiency in multiple-antenna relay networks
- Author
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Fan, Yijia 'Richard', Wang, Chao, Poor, H. Vincent, and Thompson, John S.
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Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods - Published
- 2009
24. Time multiplexed triple modular redundancy for single event upset mitigation
- Author
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She, Xiaoxuan and McElvain, K.S.
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Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Electronic circuits -- Properties ,Business ,Electronics ,Electronics and electrical industries - Published
- 2009
25. A novel analytical method for maximum likelihood detection in MIMO multiplexing systems
- Author
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Peng, Wei, Ma, Shaodan, Ng, Tung-sang, and Wang, Jiangzhou
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Monte Carlo method -- Usage ,Maximum likelihood estimates (Statistics) -- Methods ,MIMO communications -- Research ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods - Published
- 2009
26. Turbo equalization with cancelation of nonlinear distortion for CP-assisted and zero-padded MC-CDM schemes
- Author
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Dinis, Rui, Silva, Paulo, and Araujo, Teresa
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Error-correcting codes -- Methods ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Electric distortion -- Control ,Estimation theory - Published
- 2009
27. An enhanced data-reduction algorithm for event-triggered networks
- Author
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Miucic, Radovan, Mahmud, Syed Masud, and Popovic, Zeljko
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Algorithms -- Usage ,Electronic data processing -- Methods ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Mobile communication systems -- Research ,Wireless communication systems -- Research ,Algorithm ,Wireless technology ,Business ,Electronics ,Electronics and electrical industries ,Transportation industry - Abstract
As functionality of vehicles increases in complexity, the demand on the in-vehicle networks increases as well. Maximum bus utilization often becomes the communication bottleneck. One way to satisfy the high bandwidth requirement for future vehicles is to use a higher bandwidth bus or multiple buses. However, the use of a higher bandwidth bus increases the cost of the network. Similarly, the use of multiple buses increases the cost as well as the complexity of wiring and network handling. Both options are becoming solutions to high bandwidth demand. An alternative option is the development of a higher layer protocol that uses data-reduction (DR) techniques to reduce the amount of data to be transferred. Its goal is to communicate the same amount of information using less bus bandwidth. It would be acceptable, provided that it does not increase the message latencies significantly so that the safety of the vehicle is not compromised. The cost of the protocol is expected to be marginal because it consists of one-time changes to software. Various DR algorithms are available in the literature, but DR technology has not been introduced in in-vehicle protocol standards. This paper presents a unique DR methodology, along with its comparison with other proposed methodologies. The performance of this new DR algorithm is found to be better than that of the existing DR algorithms for a wide range of signal dynamics. The cost, as well as the impact of this protocol on the end-to-end message latency, has been found to be very marginal. Index Terms--Controller area network (CAN), data reduction (DR), event-triggered bus, in-vehicle network, multiplexing.
- Published
- 2009
28. Opportunistic beamforming communication with throughput analysis using asymptotic approach
- Author
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Xia, Minghua, Zhou, Yuanping, Ha, Jeounglak, and Chung, Hyun Kyu
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Beamforming -- Methods ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Rayleigh scattering -- Observations ,Communications circuits -- Design and construction ,Business ,Electronics ,Electronics and electrical industries ,Transportation industry - Abstract
The opportunistic beamforming system (OBS) is currently receiving much attention in the field of downlink beamforming due to its simple random beamforming, low feedback complexity, and same throughput scaling obtained with perfect channel-state information using dirty paper coding at the transmitter. In this paper, we focus on its closed-form throughput evaluation over Rayleigh fading channels, based on the asymptotic theory of extreme order statistics. First, the throughput of a single-beam OBS is investigated, and an analytical solution tighter than the previously reported one is derived. Then, the asymptotic throughput bounds on a multibeam OBS are presented, and also, our analytical expression is shown to be very tight with the simulation results even with fewer users. After that, we argue that the reported conclusion that the single-beam OBS is much preferable to the multibeam OBS in the high-signal-to-noise-ratio (SNR) regime is inaccurate, but that, instead, it is satisfied only when the number of users is very small, due to its limited multiuser diversity gain. Finally, we show that four transmit beams is the most preferable in the multibeam OBS with a large number of users and moderate SNR, which arrives at the tradeoff between increasing spatial multiplexing gain and disappearing multiuser diversity gain. Index Terms--Multiple-input single-output (MISO), multiuser diversity, opportunistic beamforming system (OBS), spatial multiplexing, throughput.
- Published
- 2009
29. Toward a multiplexed solid-phase nucleic acid hybridization assay using quantum dots as donors in fluorescence resonance energy transfer
- Author
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Algar, W. Russ and Krull, Ulrich J.
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Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Nucleic acid hybridization -- Methods ,Semiconductors -- Usage ,Semiconductors -- Properties ,Fluorescence -- Research ,Resonance -- Research ,Energy transformation -- Research ,Chemistry - Abstract
Solid-phase assays using immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET) have been developed for the selective detection of nucleic acids. QDs were immobilized on optical fibers and conjugated with probe oligonucleotides. Hybridization with acceptor labeled target oligonucleotides generated FRET-sensitized acceptor fluorescence that was used as the analytical signal. A sandwich assay was also introduced and avoided the need for target labeling. Green and red emitting CdSe/ZnS QDs were used as donors with Cy3 and Alexa Fluor 647 acceptors, respectively. Quantitative measurements were made via spectrofluorimetry or fluorescence microscopy. Detection limits as low as 1 nM were obtained, and the discrimination of single nucleotide polymorphisms (SNPs) with contrast ratios as high as 31:1 was possible. The assays retained their selectivity and at least 50% of their signal when tested in bovine serum and against a large background of noncomplementary genomic DNA. Mixed films of the two colors of QD and two probe oligonucleotide sequences were prepared for multiplexed solid-phase hybridization assays. It was possible to simultaneously detect two target sequences with retention of selectivity, including SNP discrimination. This research provides an important precedent and framework for the future development of QD-based bioassays and biosensors.
- Published
- 2009
30. Interleaved random space-time coding for multisource cooperation
- Author
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Zhang, Rong and Hanzo, Lajos
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Coding theory -- Research ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Mobile communication systems -- Standards ,Wireless communication systems -- Standards ,Wireless technology ,Business ,Electronics ,Electronics and electrical industries ,Transportation industry - Abstract
In this paper, we propose a novel distributed interleaved random space-time code (IR-STC) designed for multisource cooperation (MSC) employing various relaying techniques, namely, amplify-forward, decode-forward, soft decode-forward, and differential decode-forward. We introduce a two-phase communication regime for our IR-STC-aided MSC and propose a novel structured embedded (SE) random interleaver-generation method. We also characterize the achievable performance of our proposed IR-STC design in conjunction with various relaying techniques communicating over different intersource Nakagami-m fading channels. Index Terms--Cooperative communications, interleaver division multiplexing, relaying, space-time coding.
- Published
- 2009
31. Tilt error measurement and compensation method for the holographic data storage system using disturbance observer
- Author
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Kim, Sang-Hoon, Kim, Jang Hyun, Lee, YongHee, Yang, Hyunseok, Park, Joo-Youn, Park, Kyoung-Su, and Park, Young-Pil
- Subjects
Holography -- Methods ,Information storage and retrieval systems -- Research ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Angle -- Influence ,Information storage and retrieval -- Methods ,Servomechanisms -- Research ,Business ,Electronics ,Electronics and electrical industries - Abstract
Tilt error can affect a serious effect to holographic data storage system using angle(polytopic) multiplexing. Because the tolerance about tilt error is very tight it is important to measure the tilt error and compensate it. In this paper, tilt error measurement system with additional red laser and reflection geometry is suggested and servo control experiments are conducted. A servo controller to compensate tilt error is designed using disturbance observer. Amount of tilt is decreased smaller than 0.01 degree and signal-to-noise ratio is increased with the tilt servo controller when 0.216 degree of tilt disturbance is applied. Index Terms--Holographic memories, servosystems.
- Published
- 2009
32. A simple dual-mode limited feedback multiuser downlink system
- Author
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Au-Yeung, Chun Kin, Park, Seung Young, and Love, David J.
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Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Electromagnetic interference -- Control ,Feedback (Electronics) -- Methods - Abstract
Generally limited feedback systems that multiplex multiple user signals are noise power limited in the low signal-to-noise-ratio (SNR) regime and interference power limited in the high SNR regime. If the amount of feedback does not grow with SNR, then there is a sum rate ceiling that increasing the transmit power alone cannot surpass. This paper proposes a simple dual mode system where the base station serves either one user or as many users as the number of transmit antennas. The switching mechanism is smooth and is based on instantaneous system conditions. The mobile determines its preferred transmission mode by using a very simple signal-to-interference-and-noise-ratio (SINR) threshold. Based on the mobiles' feedback, the base station chooses the method of signalling accordingly. With a finite number of feedback bits per mobile, it is shown that the proposed system achieves close to the maximum of the sum-rate for single user and multiuser modes. We identify the preferrable mode for an asymptotically large number of users and/or SNR. This proposed architecture is suitable for systems with moderate coherence time, a moderate to large number of users, and a moderate SNR that cannot afford complex processing at the base station or at the mobile. Index Terms--Gaussian broadcast system, dual mode multiuser system, sum-rate ceiling.
- Published
- 2009
33. Bit-interleaved coded multiple beamforming with imperfect CSIT
- Author
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Sengul, Ersin, Park, Hong Ju, and Ayanoglu, Ender
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Algorithm ,Algorithms -- Usage ,Modulation (Electronics) -- Methods ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Feedback (Electronics) -- Methods - Abstract
This paper addresses the performance of bit-interleaved coded multiple beamforming (BICMB) [1], [2] with imperfect knowledge of beamforming vectors. Most studies for limited-rate channel state information at the transmitter (CSIT) assume that the precoding matrix has an invariance property under an arbitrary unitary transform. In BICMB, this property does not hold. On the other hand, the optimum precoder and detector for BICMB are invariant under a diagonal unitary transform. In order to design a limited-rate CSIT system for BICMB, we propose a new distortion measure optimum under this invariance. Based on this new distortion measure, we introduce a new set of centroids and employ the generalized Lloyd algorithm for codebook design. We provide simulation results demonstrating the performance improvement achieved with the proposed distortion measure and the codebook design for various receivers with linear detectors. We show that although these receivers have the same performance for perfect CSIT, their performance varies under imperfect CSIT. Index Terms--Beamforming, Bit-interleaved coded modulation, diversity, spatial multiplexing, limited feedback, BICMB.
- Published
- 2009
34. Wavelength multiplexing encryption using joint transform correlator architecture
- Author
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Amaya, Dafne, Tebaldi, Myrian, Torroba, Roberto, and Bolognini, Nestor
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Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Wavelength -- Research ,Data encryption -- Methods ,Image processing -- Methods ,Computer-generated environments -- Methods ,Computer simulation -- Methods ,Encryption ,Astronomy ,Physics - Abstract
We show that multiple secure data recording under a wavelength multiplexing technique is possible in a joint transform correlator (JTC) arrangement. We evaluate both the performance of the decrypting procedure and the influence of the input image size when decrypting with a wavelength different from that employed in the encryption step. This analysis reveals that the wavelength is a valid parameter to conduct image multiplexing encoding with the JTC architecture. In addition, we study the influence of the minimum wavelength change that prevents decoding cross talk. Computer simulations confirm the performance of the proposed technique. OCIS codes: 070.0070, 070.4560.
- Published
- 2009
35. Optical full Hadamard matrix multiplexing and noise effects
- Author
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Streeter, L., Burling-Claridge, G.R., Cree, M.J., and Kunnemeyer, R.
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Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Random noise theory -- Research ,Poisson processes -- Research ,Imaging systems -- Methods ,Imaging systems -- Equipment and supplies ,Astronomy ,Physics - Abstract
Hadamard multiplexing provides a considerable SNR boost over additive random noise but Poisson noise such as photon noise reduces the boost. We develop the theory for full H-matrix Hadamard transform imaging under additive and Poisson noise effects. We show that H-matrix encoding results in no effect on average on the noise level due to Poisson noise sources while preferentially reducing additive noise. We use this result to explain the wavelength-dependent varying SNR boost in a Hadamard hyperspectral imager and argue that such a preferential boost is useful when the main noise source is indeterminant or varying. OCIS codes: 110.4234, 110.1758, 030.4280, 350.6980.
- Published
- 2009
36. Programmed fabrication of bimetallic nanobarcodes for miniature multiplexing bioanalysis
- Author
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Zhang, Wei-Ming, Hu, Jin-Song, Ding, Hai-Tao, Wan, Li-Jun, and Song, Wei-Guo
- Subjects
Integrated circuit fabrication -- Methods ,Bar codes -- Design and construction ,Nanotechnology -- Research ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Bioelectrochemistry -- Research ,Integrated circuit fabrication ,Chemistry - Abstract
Nanobarcodes with Morse code patterns are fabricated by a programmed electrochemical deposition process. These bimetallic nanobarcodes are stable and easy to decode using optical or electrical devices. Their discretionally patterned codes offer mass memory capacity for information carders. They show promising features as probe molecules' carriers in multiplexing bioanalysis.
- Published
- 2009
37. Spectral multiplexing method for digital snapshot spectral imaging
- Author
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Golub, Michael A., Nathan, Menachem, Averbuch, Amir, Lavi, Eitan, Zheludev, Valery A., and Schclar, Alon
- Subjects
Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Imaging systems -- Methods ,Pixels -- Research ,Resolution (Optics) -- Research ,Spectra (Spectroscopy) -- Research ,Astronomy ,Physics - Abstract
We propose a spectral imaging method for piecewise 'macropixel' objects, which allows a regular digital camera to be converted into a digital snapshot spectral imager by equipping the camera with only a disperser and a demultiplexing algorithm. The method exploits a 'multiplexed spectrum' intensity pattern, i.e., the superposition of spectra from adjacent different image points, formed on the image sensor of the digital camera. The spatial image resolution is restricted to a macropixel level in order to acquire both spectral and spatial data (i.e., an entire spectral cubet in a single snapshot. Results of laboratory experiments with a special macropixel object image, composed of small, spatially uniform squares, provide to our knowledge a first verification of the proposed spectral imaging method. OCIS codes: 110.4234, 300.6190, 260.2030.
- Published
- 2009
38. Real-time polarization mode dispersion monitoring system for a multiple-erbium-doped fiber amplifier, dense wavelength division multiplexing optical fiber transmission by amplified spontaneous emission modulation and acousto-optic tunable fiber scanning techniques
- Author
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Tseng, Bao-Jang and Tarn, Chen-Wen
- Subjects
Acoustooptics -- Research ,Polarization (Light) -- Methods ,Dispersion -- Research ,Fiber optics -- Research ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Light filters -- Properties ,Resolution (Optics) -- Research ,Fiber optics ,Astronomy ,Physics - Abstract
Without interruption or affecting the transmission of ordinary payload channels, we propose a real time polarization mode dispersion (PMD) monitoring system for long-haul, multiple erbium-doped fiber amplifier (EDFA), dense wavelength division multiplexing (DWDM) optical fiber transmission using modulated amplified spontaneous emission (ASE) of one of the EDFAs as the supervisory (SV) signal source. An acousto-optic tunable filter (AOTF) at the receiver side is adopted to scan the spectrum of the transmitted ASE SV signal. Using the fixed-analyzer method, PMDs of different wavelength bands that range from 1545 to 1580 nm of a DWDM fiber-optic communication system can be found by adaptively changing the radio frequency of the AOTF. The resolution and the measuring range of the proposed monitoring system can be significantly improved by cascading the AOTFs at the receiver side. OCIS codes: 060.4510, 230.1040.
- Published
- 2009
39. Multiplexed four-channel rectilinear ion trap mass spectrometer
- Author
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Kothari, Sameer, Song, Qingyu, Xia, Yu, Fico, Miriam, Taylor, Dennis, Amy, Jonathan W., Stafford, George, and Cooks, R. Graham
- Subjects
Mass spectrometry -- Methods ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Ions -- Properties ,Lipids -- Properties ,Ionization -- Research ,Chemistry - Abstract
A four-channel multiplexed mass spectrometer with rectilinear ion trap (RIT) mass analyzers was designed, constructed, and characterized. The system consists of four parallel atmospheric pressure ion (API) sources, four RIT mass analyzers, four sets of ion optical elements, and four conversion dynode detectors. The complete instrument is housed in a single vacuum manifold with a common vacuum system. It has a relatively small footprint, and costs and complexity were minimized and controls simplified by sharing the electronics and control modules among different channels. Each channel of the instrument can be operated in either positive or negative ion mode with a choice of ionization methods to improve the information content from an experiment. Also, the instrument is equipped with simultaneous data acquisition capabilities from all four channels, but the use of a common RF electronics system limits the degree to which the analyzer channels can be scanned independently. The instrument was characterized over the mass/charge range of 150 to 1300 Th. Mass misassignments in different ion traps because of machining and assembly tolerances were avoided by the application of supplementary direct current signals to each mass analyzer to correct mass offsets. A multiplexed automatic gain control (AGC) scheme was developed to control the ion population in each of the traps independently. These two features allow tandem mass spectrometry to be performed with an isolation window of 1 Th so trapping identical ions in all four channels. There are two principal modes of operation. In one, the same sample is analyzed in all four channels using different ionization methods to increase the information content of the analysis. In the other mode of operation, different samples are analyzed in all four channels with the same ionization method, so providing higher throughput. These capabilities were demonstrated by examining lipids produced by Escherichia coli and complex mixtures containing drugs of abuse.
- Published
- 2009
40. Optimum design of a hybrid erbium-doped fiber amplifier/fiber Raman amplifier using particle swarm optimization
- Author
-
Mowla, Alireza and Granpayeh, Nosrat
- Subjects
Erbium -- Properties ,Amplifiers (Electronics) -- Design and construction ,Amplifiers (Electronics) -- Properties ,Raman effect -- Research ,Structural optimization -- Research ,Fibers -- Properties ,Fibers -- Usage ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Astronomy ,Physics - Abstract
We propose and optimize a hybrid erbium-doped fiber amplifier/fiber Raman amplifier (EDFA/FRA). A large number of parameters of a wide-band hybrid amplifier consisting of an erbium-doped fiber amplifier (EDFA) and a fiber Raman amplifier (FRA) have been optimized using an effective and fast global optimization method called particle swarm optimization. Two types of hybrid EDFA/FRA with six- and 10-pumped FRAs have been optimized. A large number of variables affect the hybrid EDFA/FRA performance, thus we need a global optimization method to be able to deal with these variables. Particle swarm optimization helps us to find optimum parameters of a hybrid EDFA/FRA and reduce the gain spectrum variations to 2.91 and 2.03 dB for the six and 10 pumped FRAs, respectively. The optimum design supports the amplification of 60 signal channels in the wavelength range of 1529.2-1627.1 nm for a wavelength-division multiplexing system. OCIS codes: 060.2310, 060.2320.
- Published
- 2009
41. L-band automatic-gain-controlled erbium-doped fiber amplifier utilizing C-band backward-amplified spontaneous emission and electrical feedback monitor
- Author
-
Shen, Jyi-Lai, Lee, Yueh-Chien, and Huang, Chia-Chih
- Subjects
Erbium -- Properties ,Amplifiers (Electronics) -- Properties ,Amplifiers (Electronics) -- Usage ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Emission spectra -- Research ,Feedback loops (Systems theory) -- Research ,Signal processing -- Methods ,Digital signal processor ,Astronomy ,Physics - Abstract
A new L-band automatic-gain-controlled (AGC) erbium-doped fiber amplifier (EDFA) for dense wavelength-division-multiplexing transmission systems is presented, in which a single 1480 nm laser with an internal thermoelectric cooler is used as a primary pump for stable amplification. All C-band amplified spontaneous emission (ASE) is recycled by the secondary pump to enhance the gain efficiency. A fraction of the output signal is used as an electrical feedback monitor for the AGC to improve the gain-clamped (GC) flatness. Experimental results prove that the AGC EDFA has a gain flatness of better than 0.46 dB/40 nm, i.e., below 1.5%, and a higher gain of approximately 36.5 dB compared to that of approximately 35.3 dB for the conventional GC EDFA at -30 dBm input signal power. The best gain flatness of [+ or -] 0.25 dB can be achieved over the dynamic range greater than 20 dB. The dynamic range of noise figure is between 6.7 and 7.1. The 3 dB down bandwidth is more than 40nm. Overall dynamics measurements for the AGC EDFA feedback stabilization have been carried out. The recorded corresponding rise time of 1.565 ms indicates that the system does not exhibit any overshoot of gain or ASE variation due to the signal at the beginning of the pulse. OCIS codes: 140.3280, 230.4480, 060.4510.
- Published
- 2009
42. A Zipper OFDM multiple-antenna technique for interleaved-FDD cellular communication systems
- Author
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Xue, Yisheng and Leib, Harry
- Subjects
Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Communications circuits -- Design and construction ,Antennas (Electronics) -- Design and construction ,Business ,Electronics ,Electronics and electrical industries ,Transportation industry - Abstract
This paper investigates the application of Zipper orthogonal frequency-division multiplexing (OFDM), which is a frequency-domain duplexing technique based on interleaving subcarriers, to multiple-antenna cellular communications. By studying the Cramer-Rao lower bound as well as the performance of a minimum-mean-square-error-based interpolator, we show that the interleaved subcarriers make it possible for the base station to obtain accurate instantaneous downlink channel state information (CSI) from uplink channel measurements. However, the interleaved uplink and downlink subcarriers could introduce interference leakage when the intersubcarrier orthogonality is destroyed in multiple-cell environments. We address this issue by analyzing the uplink-to-downlink power leakage and show that with proper system configuration, such interference only has a marginal effect in typical land mobile radio environments. Finally, by considering maximum ratio transmission as an example, we demonstrate the benefit of knowing instantaneous downlink CSI in multiple-antenna Zipper OFDM systems. Index Terms--Cellular communication, instantaneous channel state information (CSI), interleaved frequency-domain duplexing (FDD), maximum ratio transmission (MRT).
- Published
- 2009
43. Supporting asymmetric traffic in a TDD/CDMA cellular network via interference-aware dynamic channel allocation and space-time LMMSE joint detection
- Author
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Spyropoulos, Ioannis and Zeidler, James R.
- Subjects
Communications traffic -- Management ,Electromagnetic interference -- Control ,Communications circuits -- Design and construction ,Signal detection (Electronics) -- Methods ,CDMA technology -- Research ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Code Division Multiple Access technology ,Company business management ,Business ,Electronics ,Electronics and electrical industries ,Transportation industry - Abstract
In a time-division duplexing (TDD)/code-division multiple-access (CDMA) cellular network with asymmetric data traffic, dynamic channel allocation (DCA) enhances resource utilization compared with fixed channel allocation (FCA). However, it also induces base-to-base and mobile-to-mobile crossed-slot intercell interference, which can severely degrade system performance. To deal with this problem, a decentralized scheme is proposed, which combines an interference-aware DCA algorithm with space-time linear minimum-mean-square-error (LMMSE) joint detection at the base and mobile stations. The former assigns active links to timeslots in a way that crossed-slot interference is mitigated, while the latter suppresses the remaining intercell interference (along with intersymbol and intracell interference), exploiting its spatio-temporal autocorrelation statistics. The performance of this scheme is evaluated in terms of downlink and uplink signal-to-interference-plus-noise ratio (SINR) outage and average throughput via analytical approximations and Monte Carlo simulations, and it is compared with that of benchmark random DCA (RDCA) and FCA schemes. The cases of single- and dual-antenna reception with perfect and imperfect channel state information are examined. It is shown that the proposed scheme achieves higher average throughput than FCA (particularly for dual-antenna reception) as well as RDCA (for heavy traffic loads). These throughput gains are more significant in uplink than in downlink. Index Terms--Antenna arrays, code-division multiple access (CDMA), land mobile radio cellular systems, resource management, signal detection, time-division duplexing (TDD).
- Published
- 2009
44. Performance comparison of downlink capacity improvement schemes: orthogonal code-hopping multiplexing versus multiple scrambling codes
- Author
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Jung, Bang Chul, Cho, Sung Soo, and Sung, Dan Keun
- Subjects
Coding theory -- Research ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Communications circuits -- Design and construction ,Business ,Electronics ,Electronics and electrical industries ,Transportation industry - Abstract
In this paper, we compare the performance of two downlink capacity-improvement schemes based on orthogonal code-hopping multiplexing (OCHM) and multiple scrambling codes (MSCs). Both OCHM and MSC systems have been proposed to overcome a code-limitation problem in a code division multiple access (CDMA) downlink. We mathematically analyze the user capacity in a general form, considering various factors such as user activity, spreading factor, amount of transmission symbol energy that is allocated to common control channels, amount of outer-cell interference, orthogonality factor, and sectorization factor. Numerical examples show that the capacity gain of the OCHM-based system increases as the other-cell interference decreases and the channel activity decreases. Thus, the OCHM-based system is a more effective scheme than the MSC-based system, considering that a code-limited situation more frequently occurs in the case of low other-cell interference and low channel activity. However, the OCHM-based system is more sensitive to the orthogonality factor. Index Terms--Downlink power allocation, multiple scrambling codes (MSCs), orthogonal code hopping multiplexing (OCHM), user capacity.
- Published
- 2009
45. Performance of orthogonal beamforming for SDMA with limited feedback
- Author
-
Huang, Kaibin, Andrews, Jeffrey G., and Heath, Robert W., Jr.
- Subjects
Beamforming -- Methods ,Feedback (Electronics) -- Control ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Business ,Electronics ,Electronics and electrical industries ,Transportation industry - Abstract
On the multiantenna broadcast channel, the spatial degrees of freedom support simultaneous transmission to multiple users. The optimal multiuser transmission, which is known as dirty paper coding, is not directly realizable. Moreover, close-to-optimal solutions such as Tomlinson-Harashima precoding are sensitive to channel state information (CSI) inaccuracy. This paper considers a more practical design called per user unitary and rate control (PU2RC), which has been proposed for emerging cellular standards. PU2RC supports multiuser simultaneous transmission, enables limited feedback, and is capable of exploiting multiuser diversity. Its key feature is an orthogonal beamforming (or precoding) constraint, where each user selects a beamformer (or precoder) from a codebook of multiple orthonormal bases. In this paper, the asymptotic throughput scaling laws for PU2RC with a large user pool are derived for different regimes of the signal-to-noise ratio (SNR). In the multiuser interference-limited regime, the throughput of PU2RC is shown to logarithmically scale with the number of users. In the normal SNR and noise-limited regimes, the throughput is found to scale double logarithmically with the number of users and linearly with the number of antennas at the base station. In addition, numerical results show that PU2RC achieves higher throughput and is more robust against CSI quantization errors than the popular alternative of zero-forcing beamforming if the number of users is sufficiently large. Index Terms--Broadcast channels, feedback communication, multiuser channels, space division multiplexing.
- Published
- 2009
46. Dense wavelength-division multiplexing dispersion compensators based on chirped and apodized Fibonacci structures: CA-FC(j, n)
- Author
-
Golmohammadi, Saeed, Moravvej-Farshi, Mohammad Kazem, Rostami, Ali, and Zarifkar, Abbas
- Subjects
Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Wavelength -- Research ,Dispersion -- Research ,Fibonacci numbers -- Research ,Refractive index -- Research ,Astronomy ,Physics - Abstract
Chromatic dispersion compensation is an essential feature of high speed dense wavelength-division multiplexing (DWDM) systems. We propose a dispersion compensator structure whose characteristics meet the optical DWDM system requirements. The proposed structure is based on Fibonacci quasi-periodic multilayer structures composed of layers with large index differences. Studying the dispersive properties of Fibonacci structures with generation numbers j = 3 and 4, and calculating group delay (GD) and group velocity dispersion (GVD) of their reflection bands, we have demonstrated that to have a smooth GD and almost a constant GVD in each band of a DWDM system, one needs not only to suitably chirp the structure refractive index profile, but also must properly apodize it. We also demonstrate the possibility of achieving high slope GDs and large GVDs by means of high order Fibonacci structures with thicker layers. Finally, by varying the layer dimensions and refractive indices as well as Fibonacci's order, one can design DWDM dispersion compensators suitable for distances as long as 220 km. OCIS codes: 050.1590, 060.4510, 230.2035, 220.1230, 230.4170, 130.2035.
- Published
- 2008
47. Three design aspects of Multicarrier Interleave Division Multiple Access
- Author
-
Zhang, Rong and Hanzo, Lajos
- Subjects
Algorithms -- Usage ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Transceivers -- Design and construction ,Electromagnetic interference -- Control ,Algorithm ,Transceiver ,Business ,Electronics ,Electronics and electrical industries ,Transportation industry - Abstract
This paper presents a novel generalized transceiver architecture, i.e., Multicarrier Interleave-Division-Multiplexing. aided Interleave Division Multiple Access (MC-IDM-IDMA). A parallel interference cancellation (PIC)-aided iterative multiuser detection (MUD) algorithm, is introduced, and the convergence behavior of the system is evaluated with the aid of EXtrinsic Information Transfer (EXIT) charts under the assumption of an equal-power multiuser scenario. Three interesting design tradeoffs of the MC-IDM-IDMA system are analyzed: 1) the multiplexing versus diversity tradeoffs; 2) the coding versus spreading tradeoffs, where the achievable bandwidth efficiency of both MC-IDM and MC-IDMA are characterized, and a general design rule is provided for low-rate codes; and 3) the complexity versus performance tradeoffs and the EXIT characteristics of two different MUD algorithms are investigated, leading to a reduced-complexity hybrid MUD. Index Terms--EXtrinsic Information Transfer (EXIT) charts, interleave division multiplexing/interleave division multiple access (IDM/IDMA), multicarrier (MC), multiuser detection (MUD).
- Published
- 2008
48. Study of CMOS process variation by multiplexing analog characteristics
- Author
-
Gettings, Karen M.G.V. and Boning, Duane S.
- Subjects
Complementary metal oxide semiconductors -- Design and construction ,Statistical models -- Usage ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
Aggressive technology scaling raises the need for efficient methods to characterize and model circuit variation at both the front and back end of line, where critical parameters such as threshold voltage and parasitic capacitance must be carefully modeled for accurate circuit performance. In this paper we address this need by contributing a test circuit methodology for the extraction of spatial, layout and size dependent variations at both device and interconnect levels. The test chip uses a scan chain approach combined with low-leakage and low-variation switches, and Kelvin sensing connections, providing access to detailed analog device characteristics in large arrays of test devices. Variation measurement using the designed test chip has proven successful for both device and interconnect test structures. The parameter extraction and variation analyses made possible by the variation test chip enable the identification of likely variation sources, quantification of circuit impact and sensitivity, and specification of layout practices for variation minimization. Index Terms--Design for manufacturability, statistical metrology, statistical modeling, variation.
- Published
- 2008
49. Bayesian analysis of interference cancellation for Alamouti multiplexing
- Author
-
Sirianunpiboon, Songsri, Calderbank, A. Robert, and Howard, Stephen D.
- Subjects
Algorithm ,Algorithms -- Usage ,Bayesian statistical decision theory -- Methods ,Electromagnetic interference -- Control ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Coding theory -- Research - Abstract
Space--time codes built out of Alamouti components have been adopted in wireless standards such as UMTS, IEEE 802.11n, and IEEE 802.16, where they facilitate higher data rates through multiplexing of parallel data streams and the addition of two or more antennas at the receiver that perform interference cancellation. This correspondence provides new theoretical insight into different algorithms for interference cancellation through a Bayesian analysis that expresses performance as a function of signal-to-noise ratio (SNR) in terms of the "angles" between different space-time coded data streams. Index Terms--Alamouti code, Bayesian analysis, decoding algorithms, interference cancellation, Quaternion arithmetic, space-time block codes.
- Published
- 2008
50. Decode-and-forward relaying with quantized channel state feedback: an outage exponent analysis
- Author
-
Kim, Tung T., Caire, Giuseppe, and Skoglund, Mikael
- Subjects
Communications circuits -- Design and construction ,Digital multiplexing -- Methods ,Multichannel communication -- Methods ,Multiplexing -- Methods ,Information theory -- Research ,Relays -- Design and construction ,Feedback (Electronics) -- Evaluation - Abstract
The problem of resource allocation to maximize the outage exponent over a fading relay channel using the decode-and-forward protocol with quantized channel state feedback (CSF) is studied. Three different scenarios are considered: relay-to-source, destination-to-relay, and destination-to-source-and-relay CSF. In the relay-to-source CSF scenario, it is found that using merely one bit of CSF to control the source transmit power is sufficient to achieve the multiantenna upper bound in a range of multiplexing gains. In the destination-to-relay CSF scenario, the systems slightly outperform dynamic decode-and-forward (DDF) at high multiplexing gains, even with only one bit of feedback. Finally, in the destination-to-source-and-relay CSF scenario, if the source-relay channel gain is unknown to the feedback quantizer at the destination, the diversity gain only grows linearly in the number of feedback levels, in sharp contrast to an exponential growth for multiantenna channels. In this last scenario, a simple scheme is shown to perform close to the corresponding upper bound. Index Terms--Cooperative communications, diversity methods, diversity-multiplexing tradeoff, fading channels, large-deviation analysis, power control, relay channels.
- Published
- 2008
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