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MIMO-OFDM
Multiple-input, multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) is the dominant air interface for 4G and 5G broadband wireless communications. It combines multiple-input, multiple-output (MIMO) technology, which multiplies capacity by transmitting different signals over multiple antennas, and orthogonal frequency-division multiplexing (OFDM), which divides a radio channel into a large number of closely spaced subchannels to provide more reliable communications at high speeds. Research conducted during the mid-1990s showed that while MIMO can be used with other popular air interfaces such as time-division multiple access (TDMA) and code-division multiple access (CDMA), the combination of MIMO and OFDM is most practical at higher data rates. MIMO-OFDM is the foundation for most advanced wireless local area network (wireless LAN) and mobile broadband network standards because it achieves the greatest spectral efficiency and, therefore, delivers the highest cap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MIMO
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 4), IEEE 802.11ac (Wi-Fi 5), HSPA+ (3G), WiMAX, and Long Term Evolution (LTE). More recently, MIMO has been applied to power-line communication for three-wire installations as part of the ITU G.hn standard and of the HomePlug AV2 specification. At one time, in wireless the term "MIMO" referred to the use of multiple antennas at the transmitter and the receiver. In modern usage, "MIMO" specifically refers to a class of techniques for sending and receiving more than one data signal simultaneously over the same radio channel by exploiting multipath propagation. Additionally, modern MIMO usage often refers to multiple data signals sent to different receivers (with one or more receiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gregory Raleigh
Gregory “Greg” Raleigh (born 1961 in Orange, California), 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. Biography Raleigh received a B.S.E.E. degree from the California Polytechnic State University, an M.S.E.E. degree from Stanford University, and a Ph.D. from Stanford University. He joined Watkins-Johnson Company in 1984 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cooperative MIMO
In radio, cooperative multiple-input multiple-output (cooperative MIMO, CO-MIMO) is a 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. Conventional MIMO systems, known as point-to-point MIMO or collocated MIMO, require both the transmitter and receiver of a communication link to be equipped with multiple antennas. While 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 (4G), many wireless devices cannot support multiple antennas due to size, cost, and/or hardware limitations. More importantly, the separation between antennas on a mobile device and even on fixed radio platforms is often insufficient to allow meaningful performance gains. Furthermore, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airgo Networks
Airgo Networks (formerly Woodside Networks), is a Palo Alto, California-based company specializing in the development of multiple-input multiple-output (MIMO) wireless technology Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most .... Airgo Networks was founded in 2001 by Gregory Raleigh, V.K. Jones, David Johnson, Geert Awater, Rolf de Vegt and Richard van Nee. Airgo was a lead proponent of the 802.11n standard. The company began shipping the world’s first MIMO-OFDM chipsets in 2003. In September 2005, Airgo Networks launched its third generation True MIMO chip set with support for data rates up to 240 Mbit/s. On December 3, 2006, List of Qualcomm Snapdragon systems-on-chip, Qualcomm announced that it would acquire Airgo Networks for an undisclosed amount. Airgo is now owned by Qua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Interface
The air interface, or access mode, is the communication link between the two stations in mobile or wireless communication. The air interface involves both the physical and data link layers (layer 1 and 2) of the OSI model for a connection. Physical Layer The physical connection of an air interface is generally radio-based. This is usually a point to point link between an active base station and a mobile station. Technologies like Opportunity-Driven Multiple Access (ODMA) may have flexibility regarding which devices serve in which roles. Some types of wireless connections possess the ability to broadcast or multicast. Multiple links can be created in limited spectrum through FDMA, TDMA, or SDMA. Some advanced forms of transmission multiplexing combine frequency- and time-division approaches like OFDM or CDMA. In cellular telephone communications, the air interface is the radio-frequency portion of the circuit between the cellular phone set or wireless modem (usually portable or m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clarity Wireless
Cisco is an American computer networking company. Cisco made its first Takeover, acquisition in 1993, which was followed by a series of further acquisitions. History Founded in 1984, Cisco did not acquire a company during the first seven years of its existence; but, on September 24, 1993, Cisco acquired Crescendo Communications, a LAN switching company. Following the first Cisco takeover purchase, acquisitions have constituted 50 percent of the company's business activity. The company's largest acquisition is the purchase of Scientific-Atlanta—a manufacturer of cable television, telecommunications and broadband equipment—for United States dollar, US$6.9 billion. The purchase represented the interest that Cisco had in Internet television, as spending on switches and routers decreased, and expanded the corporation's consumer product base after its prior acquisition of Linksys Inc., a producer of wireless networking products for homes and small businesses. Cisco chief executive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rake Receiver
A rake receiver is a radio receiver designed to counter the effects of multipath fading. It does this by using several "sub-receivers" called ''fingers'', that is, several correlators each assigned to a different multipath component. Each finger independently decodes a single multipath component; at a later stage the contribution of all fingers are combined in order to make the most use of the different transmission characteristics of each transmission path. This could very well result in higher signal-to-noise ratio (or Eb/N0) in a multipath environment than in a "clean" environment. The multipath channel through which a radio wave transmits can be viewed as transmitting the original (line of sight) wave pulse through a number of multipath components. Multipath components are delayed copies of the original transmitted wave traveling through a different echo path, each with a different magnitude and time-of-arrival at the receiver. Since each component contains the original infor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discrete Multi-tone
Discrete may refer to: *Discrete particle or quantum in physics, for example in quantum theory *Discrete device, an electronic component with just one circuit element, either passive or active, other than an integrated circuit *Discrete group, a group with the discrete topology *Discrete category, category whose only arrows are identity arrows *Discrete mathematics, the study of structures without continuity *Discrete optimization, a branch of optimization in applied mathematics and computer science *Discrete probability distribution, a random variable that can be counted *Discrete space, a simple example of a topological space *Discrete spline interpolation, the discrete analog of ordinary spline interpolation *Discrete time, non-continuous time, which results in discrete-time samples *Discrete variable In mathematics and statistics, a quantitative variable may be continuous or discrete if they are typically obtained by ''measuring'' or ''counting'', respectively. If it can ta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Sequence Spread Spectrum
In telecommunications, direct-sequence spread spectrum (DSSS) is a spread-spectrum modulation technique primarily used to reduce overall signal interference. The direct-sequence modulation makes the transmitted signal wider in bandwidth than the information bandwidth. After the despreading or removal of the direct-sequence modulation in the receiver, the information bandwidth is restored, while the unintentional and intentional interference is substantially reduced. The first known scheme for this technique was introduced by a Swiss inventor, Gustav Guanella. With DSSS, the message bits are modulated by a pseudorandom bit sequence known as a spreading sequence. Each spreading-sequence bit, which is known as a chip, has a much shorter duration (larger bandwidth) than the original message bits. The modulation of the message bits scrambles and spreads the pieces of data, and thereby results in a bandwidth size nearly identical to that of the spreading sequence. The smaller the ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrature Amplitude Modulation
Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. It conveys two analog message signals, or two digital bit streams, by changing (''modulating'') the amplitudes of two carrier waves, using the amplitude-shift keying (ASK) digital modulation scheme or amplitude modulation (AM) analog modulation scheme. The two carrier waves are of the same frequency and are out of phase with each other by 90°, a condition known as orthogonality or quadrature. The transmitted signal is created by adding the two carrier waves together. At the receiver, the two waves can be coherently separated (demodulated) because of their orthogonality property. Another key property is that the modulations are low-frequency/low-bandwidth waveforms compared to the carrier frequency, which is known as the narrowband assumption. Phase modulation (analog PM) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wireless Access Point
In computer networking, a wireless access point (WAP), or more generally just access point (AP), is a networking hardware device that allows other Wi-Fi devices to connect to a wired network. As a standalone device, the AP may have a wired connection to a router, but, in a wireless router, it can also be an integral component of the router itself. An AP is differentiated from a hotspot which is a physical location where Wi-Fi access is available. Connections An AP connects directly to a wired local area network, typically Ethernet, and the AP then provides wireless connections using wireless LAN technology, typically Wi-Fi, for other devices to use that wired connection. APs support the connection of multiple wireless devices through their one wired connection. Wireless data standards There are many wireless data standards that have been introduced for wireless access point and wireless router technology. New standards have been created to accommodate the increasing n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multi-user MIMO
Multi-user MIMO (MU-MIMO) is a set of multiple-input and multiple-output (MIMO) technologies for multipath wireless communication, in which multiple users or terminals, each radioing over one or more antennas, communicate with one another. In contrast, single-user MIMO (SU-MIMO) involves a single multi-antenna-equipped user or terminal communicating with precisely one other similarly equipped node. Analogous to how OFDMA adds multiple-access capability to OFDM in the cellular-communications realm, MU-MIMO adds multiple-user capability to MIMO in the wireless realm. SDMA,N. JindalMIMO Broadcast Channels with Finite Rate Feedback IEEE Transactions on Information Theory, vol. 52, no. 11, pp. 5045–5059, 2006.D. Gesbert, M. Kountouris, R.W. Heath Jr., C.-B. Chae, and T. SälzerShifting the MIMO Paradigm IEEE Signal Processing Magazine, vol. 24, no. 5, pp. 36-46, 2007.R. Tweg, R. Alpert, H. Leizerovich, A. Steiner, E. Levitan, E. Offir-Arad, A.B. Guy, B. Zickel, A. Aviram, A. Frieman, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
