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Orthogonal Time Frequency And Space
Orthogonal Time Frequency Space (OTFS) is a 2D modulation technique that transforms the information carried in the Delay-Doppler coordinate system. The information is transformed in the similar time-frequency domain as utilized by the traditional schemes of modulation such as TDMA, CDMA, and OFDM. It was first used for fixed wireless, and is now a contending waveform for 6G technology due to its robustness in high-speed vehicular scenarios. OTFS is intimately related to an earlier modulation 2D modulation scheme - called orthogonal short-time Fourier (OSTF) signaling - and is related to it through a 2D discrete Fourier transform. In this regard, OTFS is simply a precoded version of OSTF. Yet, OSTF defines the critical analog-digital interface that is matched to the characteristics of the time-varying wireless channel. __TOC__ Overview OTFS is a modulation scheme where each transmitted symbol experiences a near-constant channel gain even in channels at high carrier frequenci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delay Doppler
Delay Doppler coordinates are coordinates typically used in a radar technology-inspired approach to measurement. When used in wireless communication, the Delay Doppler domain mirrors the geometry of the reflectors comprising the wireless channel, which changes far more slowly than the phase changes experienced in the rapidly varying time-frequency domain. Delay Doppler Signal Representation In radar theory, the Delay Doppler variables are used to represent and separate moving targets through their delay (range) and Doppler (velocity) characteristics. In communication, the variables represent channels through a superposition of time and frequency shift operations. Delay Doppler variables can also represent information-carrying signals. The Delay Doppler signal representation, sometimes referred to as the lattice representation of the Heisenberg group, is in a sense a hybrid of the traditional time and frequency representations. In the time representation, a signal is realized as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital AMPS
IS-54 and IS-136 are second-generation ( 2G) mobile phone systems, known as Digital AMPS (D-AMPS), and a further development of the North American 1G mobile system Advanced Mobile Phone System (AMPS). It was once prevalent throughout the Americas, particularly in the United States and Canada since the first commercial network was deployed in 1993. D-AMPS is considered end-of-life, and existing networks have mostly been replaced by GSM/GPRS or CDMA2000 technologies. This system is most often referred to as TDMA. That name is based on the abbreviation for time-division multiple access, a common multiple access technique which is used in most 2G standards, including GSM, as well as in IS-54 and IS-136. D-AMPS competed against GSM and systems based on code-division multiple access (CDMA). D-AMPS uses existing AMPS channels and allows for smooth transition between digital and analog systems in the same area. Capacity was increased over the preceding analog design by dividing each ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CDMA
Code-division multiple access (CDMA) is a channel access method used by various radio communication technologies. CDMA is an example of multiple access, where several transmitters can send information simultaneously over a single communication channel. This allows several users to share a band of frequencies (see bandwidth). To permit this without undue interference between the users, CDMA employs spread spectrum technology and a special coding scheme (where each transmitter is assigned a code). CDMA optimizes the use of available bandwidth as it transmits over the entire frequency range and does not limit the user's frequency range. It is used as the access method in many mobile phone standards. IS-95, also called "cdmaOne", and its 3G evolution CDMA2000, are often simply referred to as "CDMA", but UMTS, the 3G standard used by GSM carriers, also uses "wideband CDMA", or W-CDMA, as well as TD-CDMA and TD-SCDMA, as its radio technologies. It can be also used as a channel or m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthogonal Frequency-division Multiplexing
In telecommunications, orthogonal frequency-division multiplexing (OFDM) is a type of digital transmission and a method of encoding digital data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital communication, used in applications such as digital television and audio broadcasting, DSL internet access, wireless networks, power line networks, and 4G/ 5G mobile communications. OFDM is a frequency-division multiplexing (FDM) scheme that was introduced by Robert W. Chang of Bell Labs in 1966. In OFDM, multiple closely spaced orthogonal subcarrier signals with overlapping spectra are transmitted to carry data in parallel.webe.org - 2GHz BAS Relocation Tech-Fair, COFDM Technology Basics 2007-03-02 Demodula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
6G (network)
In telecommunications, 6G is the sixth generation mobile system standard currently under development for wireless communications technologies supporting cellular data networks. It is the planned successor to 5G and will likely be significantly faster. Like its predecessors, 6G networks will probably be broadband cellular networks, in which the service area is divided into small geographical areas called ''cells''. Several companies (Airtel, Anritsu, Apple, Ericsson, Fly, Huawei, Jio, Keysight, LG, Nokia, NTT Docomo, Samsung, Vi, Xiaomi), research institutes ( Technology Innovation Institute) and countries (United States, European Union, China, India, Japan, South Korea, Singapore and United Arab Emirates) have shown interest in 6G networks. 6G networks are expected to be even more diverse than their predecessors and are likely to support applications beyond current mobile use scenarios, such as virtual and augmented reality (VR/AR), ubiquitous instant communications, per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zak Transform
In mathematics, the Zak transform (also known as the Gelfand mapping) is a certain operation which takes as input a function of one variable and produces as output a function of two variables. The output function is called the Zak transform of the input function. The transform is defined as an infinite series in which each term is a product of a dilation of a translation by an integer of the function and an exponential function. In applications of Zak transform to signal processing the input function represents a signal and the transform will be a mixed time–frequency representation of the signal. The signal may be real valued or complex-valued, defined on a continuous set (for example, the real numbers) or a discrete set (for example, the integers or a finite subset of integers). The Zak transform is a generalization of the discrete Fourier transform. The Zak transform had been discovered by several people in different fields and was called by different names. It was called the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wigner–Weyl Transform
In quantum mechanics, the Wigner–Weyl transform or Weyl–Wigner transform (after Hermann Weyl and Eugene Wigner) is the invertible mapping between functions in the quantum phase space formulation and Hilbert space operators in the Schrödinger picture. Often the mapping from functions on phase space to operators is called the Weyl transform or Weyl quantization, whereas the inverse mapping, from operators to functions on phase space, is called the Wigner transform. This mapping was originally devised by Hermann Weyl in 1927 in an attempt to map symmetrized ''classical'' phase space functions to operators, a procedure known as ''Weyl quantization''. It is now understood that Weyl quantization does not satisfy all the properties one would require for consistent quantization and therefore sometimes yields unphysical answers. On the other hand, some of the nice properties described below suggest that if one seeks a single consistent procedure mapping functions on the classical p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ronny Hadani
Ronny Hadani is an Israeli-American mathematician, specializing in representation theory and harmonic analysis, with applications to signal processing. He is known for developing Orthogonal Time Frequency and Space (OTFS) modulating techniques, a method used for making wireless 5G communications faster, that is also being considered for use in 6G technology. The technology is being used by several wireless 5G related companies and Cohere Technologies, a company he has co-founded. Early life and education Hadani received his MS degree in Computer Science from the Weizmann Institute of Science in 1999 under the supervision of David Harel. He received his Ph.D. degree in Pure Mathematics from Tel-Aviv University in 2006 under the supervision of Joseph Bernstein. Career Academia From the years 2006 to 2009, Hadani held an L.E. Dickson Postdoctoral Fellowship of Mathematics at the University of Chicago. Since 2009, he has been an associate professor of mathematics at the Unive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shlomo Rakib
Shlomo Rakib is an Israeli electrical engineer known for his work on Orthogonal Time Frequency and Space (OTFS) and other engineering topics. He is the holder of several patents and co-founder and current Chief Technology Officer of Cohere Technologies, which he had co-founded with Ronny Hadani. He also co-founded Terayon in 1993. Education Rakib received a Bachelor of Science in Electrical Engineering from Technion University in Israel. The university's Shlomo Rakib Fellowship Fund is named after him. Career In the 1980s, Rakib served as a communications engineer in the Israeli Navy. Rakib also served as Chief Engineer at the communications products company PhaseCom from 1981 to 1993. As part of PhaseCom, he developed data and telephony applications.https://www.sec.gov/Archives/edgar/data/1052303/000089843001500308/d10ka.txt Shlomo Rakib founded Terayon in 1993 with his brother Zaki Rakib (IPO in 1998). The company initially sold modems before developing other types of broadba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
