Weibull fading, named after Waloddi Weibull, is a simple statistical model of fading used in wireless communications and based on the Weibull distribution. Empirical studies have shown it to be an effective model in both indoor [1] and outdoor [2] environments.
In 2005, a theoretical model for a particular class of Weibull distributions was described by Sagias and Karagiannidis, [3] who also analyzed channel capacity of a wireless channel in the presence of Weibull fading. [4]
In telecommunications, orthogonal frequency-division multiplexing (OFDM) is a type of digital modulation, 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 mobile communications.
Rayleigh fading is a statistical model for the effect of a propagation environment on a radio signal, such as that used by wireless devices.
In probability theory and statistics, the Weibull distribution is a continuous probability distribution. It is named after Swedish mathematician Waloddi Weibull, who described it in detail in 1951, although it was first identified by Fréchet (1927) and first applied by Rosin & Rammler (1933) to describe a particle size distribution.
Information-theoretic security is a cryptosystem whose security derives purely from information theory; the system cannot be broken even if the adversary has unlimited computing power. The cryptosystem is considered cryptanalytically unbreakable if the adversary does not have enough information to break the encryption.
A space–time code (STC) is a method employed to improve the reliability of data transmission in wireless communication systems using multiple transmit antennas. STCs rely on transmitting multiple, redundant copies of a data stream to the receiver in the hope that at least some of them may survive the physical path between transmission and reception in a good enough state to allow reliable decoding.
Non-coherent space time codes are a way of transmitting data in wireless communications. In this multiple antenna scheme, it is assumed that the receiver only has knowledge of the statistics of channel. Non-coherent space-time transmission schemes were proposed by Tom Marzetta and Bertrand Hochwald in 1999, but these schemes are complex in terms of implementation.
A wireless ad hoc network (WANET) or Mobile ad hoc network (MANET) is a decentralised type of wireless network. The network is ad hoc because it does not rely on a pre-existing infrastructure, such as routers in wired networks or access points in managed (infrastructure) wireless networks. Instead, each node participates in routing by forwarding data for other nodes, so the determination of which nodes forward data is made dynamically on the basis of network connectivity and the routing algorithm in use.
In radio, Cooperative multiple-input multiple-output is an advanced technology that can effectively exploit the spatial domain of mobile fading channels to bring significant performance improvements to wireless communication systems. It is also called Network MIMO, Distributed MIMO, Virtual MIMO, and Virtual Antenna Arrays.
An indoor positioning system (IPS) is a network of devices used to locate people or objects where GPS and other satellite technologies lack precision or fail entirely, such as inside multistory buildings, airports, alleys, parking garages, and underground locations. A large variety of techniques and devices are used to provide indoor positioning ranging from reconfigured devices already deployed such as smartphones, WiFi and Bluetooth antennas, digital cameras, and clocks; to purpose built installations with relays and beacons strategically placed throughout a defined space. IPS has broad applications in commercial, military, retail, and inventory tracking industries. There are several commercial systems on the market, but no standards for an IPS system. Instead each installation is tailored to spatial dimensions, building materials, accuracy needs, and budget constraints. Lights, radio waves, magnetic fields, acoustic signals, and behavioral analytics are all used in IPS networks. IPS can achieve position accuracy of 2cm, which is on par with RTK enabled GNSS receivers that can achieve 2cm accuracy outdoors.
In radio, multiple-input and multiple-output, or MIMO, is a method for multiplying the capacity of a radio link using multiple transmission and receiving antennas to exploit multipath propagation. MIMO has become an essential element of wireless communication standards including IEEE 802.11n (Wi-Fi), IEEE 802.11ac (Wi-Fi), HSPA+ (3G), WiMAX (4G), and Long Term Evolution. More recently, MIMO has been applied to power-line communication for 3-wire installations as part of ITU G.hn standard and HomePlug AV2 specification.
Theoretically, the performance of wireless communication systems can be improved by having multiple antennas at the transmitter and the receiver. The idea is that if the propagation channels between each pair of transmit and receive antennas are statistically independent and identically distributed, then multiple independent channels with identical characteristics can be created by precoding and be used for either transmitting multiple data streams or increasing the reliability. In practice, the channels between different antennas are often correlated and therefore the potential multi antenna gains may not always be obtainable. This is called spatial correlation as it can be interpreted as a correlation between a signal's spatial direction and the average received signal gain.
In statistics, the exponentiated Weibull family of probability distributions was introduced by Mudholkar and Srivastava (1993) as an extension of the Weibull family obtained by adding a second shape parameter.
Georgios B. Giannakis is a Greek–American Professor, engineer, and inventor. At present he is an Endowed Chair Professor of Wireless Telecommunications with the Department of Electrical and Computer Engineering, and Director of the Digital Technology Center at the University of Minnesota.
In mathematics and telecommunications, stochastic geometry models of wireless networks refer to mathematical models based on stochastic geometry that are designed to represent aspects of wireless networks. The related research consists of analyzing these models with the aim of better understanding wireless communication networks in order to predict and control various network performance metrics. The models require using techniques from stochastic geometry and related fields including point processes, spatial statistics, geometric probability, percolation theory, as well as methods from more general mathematical disciplines such as geometry, probability theory, stochastic processes, queueing theory, information theory, and Fourier analysis.
The first smart antennas were developed for military communications and intelligence gathering. The growth of cellular telephone in the 1980s attracted interest in commercial applications. The upgrade to digital radio technology in the mobile phone, indoor wireless network, and satellite broadcasting industries created new opportunities for smart antennas in the 1990s, culminating in the development of the MIMO technology used in 4G wireless networks.
Gregory “Greg” Raleigh, is an American radio scientist, inventor, and entrepreneur who has made contributions in the fields of wireless communication, information theory, mobile operating systems, medical devices, and network virtualization. His discoveries and inventions include the first wireless communication channel model to accurately predict the performance of advanced antenna systems, the MIMO-OFDM technology used in contemporary Wi-Fi and 4G wireless networks and devices, higher accuracy radiation beam therapy for cancer treatment, improved 3D surgery imaging, and a cloud-based Network Functions Virtualization platform for mobile network operators that enables users to customize and modify their smartphone services.
Time Slotted Channel Hopping or Time Synchronized Channel Hopping (TSCH) is a channel access method for shared medium networks.
In radio propagation, two-wave with diffuse power (TWDP) fading is a model that explains why a signal is strengthened or weakened at certain locations or times. TWDP models fading due to the interference of two strong radio signals and numerous smaller, diffuse signals.
Ranjan Kumar Mallik is an Indian electrical and communications engineer and a professor at the Department of Electrical Engineering of the Indian Institute of Technology, Delhi. He held the Jai Gupta Chair at IIT Delhi from 2007 to 2012 and the Brigadier Bhopinder Singh Chair from 2012 to 2017. He is known for his researches on multiple-input multi-output systems and is an elected fellow of all the three major Indian science academies viz. Indian Academy of Sciences, Indian National Science Academy, and The National Academy of Sciences, India. He is also an elected fellow of The World Academy of Sciences, Indian National Academy of Engineering, and The Institute of Electrical and Electronics Engineers, Inc.
Sergio Barbarossa is an Italian professor, engineer and inventor. He is a professor at Sapienza University of Rome, Italy.
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