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Spatial Modulation
Spatial modulation is a technique that enables modulation over space, across different antennas (radio) at a transmitter. Unlike multiple-input and multiple-output (MIMO) wireless (where all the transmitting antennas are active and transmitting digital modulated symbols such as phase-shift keying and quadrature amplitude modulation), in spatial modulation, only a single antenna among all transmitting antennas is active and transmitting, while all other remaining transmitting antennas sit idle. The duty of the receiver (information theory) is: to estimate the active antenna index at the transmitter and to decode the symbol sent by the transmitting antenna. Both processes carry a message bit. Since only one transmitting antenna is active at a particular instant, one single RF chain for the active antenna is required, unlike MIMO systems in which ''N''T (number of transmitting antennas) antennas are active and correspondingly ''N''T number of RF chains are required. RF chains are co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the '' carrier signal'', with a separate signal called the ''modulation signal'' that typically contains information to be transmitted. For example, the modulation signal might be an audio signal representing sound from a microphone, a video signal representing moving images from a video camera, or a digital signal representing a sequence of binary digits, a bitstream from a computer. The carrier is higher in frequency than the modulation signal. In radio communication the modulated carrier is transmitted through space as a radio wave to a radio receiver. Another purpose is to transmit multiple channels of information through a single communication medium, using frequency-division multiplexing (FDM). For example in cable television which uses FDM, many carrier signals, each modulated with a different television channel, are transported throug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RF Chain
An RF chain is a cascade of electronic components and sub-units which may include RF power amplifier, amplifiers, RF and microwave filter, filters, Frequency mixer, mixers, Attenuator (electronics), attenuators and Detector (radio), detectors.Steer M., "Microwave and RF Design", Scitech Publ., Inc., N.C., 2010, also from Yes Dee Publ., India, 2016 It can take many forms, for example, as a wide-band receiver-detector for electronic warfare (EW) applications, as a tunable narrow-band receiver for communications purposes, as a repeater in signal distribution systems, or as an amplifier and Block upconverter, up-converters for a transmitter-driver. In this article, the term RF (radio frequency) covers the frequency range "Medium Frequencies" up to "Microwave Frequencies", i.e. from 100 kHz to 20 GHz.Frenzel L.E.” Principles of Electronic Communication Systems”, 3rd Ed.,McGraw Hill, 2008 The key electrical parameters for an RF chain are system gain, noise figure (or noise f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Resource Management
Radio resource management (RRM) is the system level management of co-channel interference, radio resources, and other radio transmission characteristics in wireless communication systems, for example cellular networks, wireless local area networks, wireless sensor systems, and radio broadcasting networks. RRM involves strategies and algorithms for controlling parameters such as transmit power, user allocation, beamforming, data rates, handover criteria, modulation scheme, error coding scheme, etc. The objective is to utilize the limited radio-frequency spectrum resources and radio network infrastructure as efficiently as possible. RRM concerns multi-user and multi-cell network capacity issues, rather than the point-to-point channel capacity. Traditional telecommunications research and education often dwell on channel coding and source coding with a single user in mind, but when several users and adjacent base stations share the same frequency channel it may not be possible to a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free-space Optical Communication
Free-space optical communication (FSO) is an optical communication technology that uses light propagating in free space to wirelessly transmit data for telecommunications or computer networking. "Free space" means air, outer space, vacuum, or something similar. This contrasts with using solids such as optical fiber cable. The technology is useful where the physical connections are impractical due to high costs or other considerations. History Optical communications, in various forms, have been used for thousands of years. The ancient Greeks used a coded alphabetic system of signalling with torches developed by Cleoxenus, Democleitus and Polybius. In the modern era, semaphores and wireless solar telegraphs called heliographs were developed, using coded signals to communicate with their recipients. In 1880, Alexander Graham Bell and his assistant Charles Sumner Tainter created the photophone, at Bell's newly established Volta Laboratory in Washington, DC. Bell considered i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectral Efficiency
Spectral efficiency, spectrum efficiency or bandwidth efficiency refers to the information rate that can be transmitted over a given bandwidth in a specific communication system. It is a measure of how efficiently a limited frequency spectrum is utilized by the physical layer protocol, and sometimes by the medium access control (the channel access protocol). Guowang Miao, Jens Zander, Ki Won Sung, and Ben Slimane, Fundamentals of Mobile Data Networks, Cambridge University Press, , 2016. Link spectral efficiency The link spectral efficiency of a digital communication system is measured in ''bit/ s/ Hz'', or, less frequently but unambiguously, in ''(bit/s)/Hz''. It is the net bit rate (useful information rate excluding error-correcting codes) or maximum throughput divided by the bandwidth in hertz of a communication channel or a data link. Alternatively, the spectral efficiency may be measured in ''bit/symbol'', which is equivalent to ''bits per channel use'' (''bpcu''), implyi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bit Numbering
In computing, bit numbering is the convention used to identify the bit positions in a binary number. Bit significance and indexing In computing, the least significant bit (LSB) is the bit position in a binary integer representing the binary 1s place of the integer. Similarly, the most significant bit (MSB) represents the highest-order place of the binary integer. The LSB is sometimes referred to as the ''low-order bit'' or ''right-most bit'', due to the convention in positional notation of writing less significant digits further to the right. The MSB is similarly referred to as the ''high-order bit'' or ''left-most bit''. In both cases, the LSB and MSB correlate directly to the least significant digit and most significant digit of a decimal integer. Bit indexing correlates to the positional notation of the value in base 2. For this reason, bit index is not affected by how the value is stored on the device, such as the value's byte order. Rather, it is a property of the num ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
M-ary Transmission
An ''M''-ary transmission is a type of digital modulation where instead of transmitting one bit at a time, two or more bits are transmitted simultaneously. This type of transmission results in reduced channel bandwidth. However, sometimes, two or more quadrature carriers are used for modulation. This process is known as quadrature modulation Quadrature may refer to: In signal processing: * Quadrature amplitude modulation (QAM), a modulation method of using both an (in-phase) carrier wave and a 'quadrature' carrier wave that is 90° out of phase with the main, or in-phase, carrier *Qu .... References An ''M''-ary Transmission Scheme for Chaotic Communications, Kai Y. Cheong, Francis C. M. Lau and Chi K. Tse. Quantized radio modulation modes Data transmission {{radio-comm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Information
Information is an abstract concept that refers to that which has the power to inform. At the most fundamental level information pertains to the interpretation of that which may be sensed. Any natural process that is not completely random, and any observable pattern in any medium can be said to convey some amount of information. Whereas digital signals and other data use discrete signs to convey information, other phenomena and artifacts such as analog signals, poems, pictures, music or other sounds, and currents convey information in a more continuous form. Information is not knowledge itself, but the meaning that may be derived from a representation through interpretation. Information is often processed iteratively: Data available at one step are processed into information to be interpreted and processed at the next step. For example, in written text each symbol or letter conveys information relevant to the word it is part of, each word conveys information relev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Message
A message is a discrete unit of communication intended by the source for consumption by some recipient or group of recipients. A message may be delivered by various means, including courier, telegraphy, carrier pigeon and electronic bus. A message can be the content of a broadcast. An interactive exchange of messages forms a conversation. One example of a message is a press release, which may vary from a brief report or statement released by a public agency to commercial publicity material. History Roles in human communication In communication between humans, messages can be verbal or nonverbal: * A verbal message is an exchange of information using words. Examples include face-to-face communication, telephone calls, voicemails, email etc. * A nonverbal message is communicated through actions or behaviors rather than words, such as conscious or unconscious body language. In computer science There are two main senses of the word "message" in computing: messa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antennas (radio)
In radio engineering, an antenna or aerial is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver. In transmission, a radio transmitter supplies an electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of a radio wave in order to produce an electric current at its terminals, that is applied to a receiver to be amplified. Antennas are essential components of all radio equipment. An antenna is an array of conductors ( elements), electrically connected to the receiver or transmitter. Antennas can be designed to transmit and receive radio waves in all horizontal directions equally (omnidirectional antennas), or preferentially in a particular direction ( directional, or high-gain, or “beam” antennas). An antenna may include components not connect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decoding (semiotics)
Decoding, in semiotics, is the process of interpreting a message sent by an addresser (sender) to an addressee (receiver). The complementary processcreating a message for transmission to an addresseeis called encoding. Overview All communication depends on the use of codes. More traditional communication models always include three main elements: a sender, a transmitter, and a receiver (Fawkes 21). The sender is responsible for “encoding” (i.e., selecting information) their message and putting it through a transmitter (i.e., a communication channel or a medium like a video, radio, text messaging, etc.) (Fawkes 21). When the encoded information, put through the transmitter, gets to the receiver, it is the responsibility of the receiver to “decode” (i.e., interpret the message) and respond accordingly with feedback (Fawkes 21). The communication process cannot work without all its three major parts: the sender/encoder, the transmitter/ medium, and the receiver/decoder. If ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Receiver (information Theory)
The receiver in information theory is the receiving end of a communication channel. It receives decoded messages/information from the sender, who first encoded them. Sometimes the receiver is modeled so as to include the decoder. Real-world receivers like radio receivers or telephones can not be expected to receive as much information as predicted by the noisy channel coding theorem In information theory, the noisy-channel coding theorem (sometimes Shannon's theorem or Shannon's limit), establishes that for any given degree of noise contamination of a communication channel, it is possible to communicate discrete data (dig .... References {{Authority control Information theory ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
