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109-545: 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 the difference in signal propagation between different antennas (e.g. due to multipath propagation ). Additionally, modern MIMO usage often refers to multiple data signals sent to different receivers (with one or more receive antennas) though this

218-400: A Rician distribution provides a more accurate model, and this is known as Rician fading . Where two components dominate, the behavior is best modeled with the two-wave with diffuse power (TWDP) distribution. All of these descriptions are commonly used and accepted and lead to results. However, they are generic and abstract/hide/approximate the underlying physics. Multipath interference is

327-402: A matrix channel which consists of all N t N r {\displaystyle N_{t}N_{r}} paths between the N t {\displaystyle N_{t}} transmit antennas at the transmitter and N r {\displaystyle N_{r}} receive antennas at the receiver. Then, the receiver gets the received signal vectors by

436-420: A MIMO system (Zheng and Tse, 2003). In particular, achieving high spatial multiplexing gains is of profound importance in modern wireless systems. Given the nature of MIMO, it is not limited to wireless communication. It can be used for wire line communication as well. For example, a new type of DSL technology (gigabit DSL) has been proposed based on binder MIMO channels. An important question which attracts

545-402: A MIMO system is increased as the number of antennas is increased, proportional to the smaller of the number of transmit antennas and the number of receive antennas. This is known as the multiplexing gain and this basic finding in information theory is what led to a spurt of research in this area. Despite the simple propagation models used in the aforementioned seminal works, the multiplexing gain

654-563: A consortium of private equity investors consisting of Kohlberg Kravis Roberts & Co. (KKR), Silver Lake Partners and AlpInvest Partners . On 21 August 2006, Bain Capital and Apax Partners announced that they had signed definitive commitments to join the acquiring consortium, a process which was completed on 1 October 2006. In 2006, Philips bought out the company Lifeline Systems headquartered in Framingham, Massachusetts , in

763-517: A deal valued at $ 750 million, its biggest move yet to expand its consumer-health business (M). In August 2007, Philips acquired the company Ximis, Inc. headquartered in El Paso, Texas , for their Medical Informatics Division. In October 2007, it purchased a Moore Microprocessor Patent (MPP) Portfolio license from The TPL Group. On 21 December 2007, Philips and Respironics, Inc. announced a definitive agreement pursuant to which Philips acquired all of

872-612: A dominant role in the entertainment industry (through PolyGram ). However, intense competition from primarily East Asian competitors throughout the 1990s and 2000s led to a period of downsizing, including the divestment of its lighting and consumer electronics divisions , and Philips' eventual reorganization into a healthcare-focused company. As of 2024, Philips is organized into three main divisions: Diagnosis and Treatment (manufacturing healthcare products such as MRI , CT and ultrasound scanners), Connected Care (manufacturing patient monitors , as well as respiratory care products under

981-407: A generator set as originally planned. The result, rated at 180/200 W electrical output from a bore and stroke of 55 mm × 27 mm , was designated MP1002CA (known as the "Bungalow set"). Production of an initial batch of 250 began in 1951, but it became clear that they could not be made at a competitive price, besides the advent of transistor radios with their much lower power requirements meant that

1090-442: A key product recall cut the company's market value by more than half over the previous year. He was to be replaced by Philips's EVP and Chief Business Leader of Connected Care, Roy Jakobs, effective 15 October 2022. In 2023, the company announced that it would be cutting 6,000 jobs from the company worldwide over the next two years after reporting 1.6 billion euros in losses during the 2022 financial year. The cuts came in addition to

1199-580: A manufacturer of devices to treat heart disease, for €1.9 billion (£1.68 billion) expanding its image-guided therapy business. In May 2016, Philips' lighting division Philips Lighting went through a spin-off process, and became an independent public company named Philips Lighting N.V. In 2017, Philips launched Philips Ventures, with a health technology venture fund as its main focus. Philips Ventures invested in companies including Mytonomy (2017) and DEARhealth (2019). On 18 July 2017, Philips announced its acquisition of TomTec Imaging Systems GmbH. In 2018,

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1308-475: A method for increasing capacity using "an array of receiving antennas at the base station" with a "plurality of remote users." Arogyaswami Paulraj and Thomas Kailath proposed an SDMA-based inverse multiplexing technique in 1993. Their US patent (No. 5,345,599 issued in 1994) described a method of broadcasting at high data rates by splitting a high-rate signal "into several low-rate signals" to be transmitted from "spatially separated transmitters" and recovered by

1417-570: A multidisciplinary sports club called PSV Eindhoven in 1913. The Philips Company was founded in 1891, by Dutch entrepreneur Gerard Philips and his father Frederik Philips. Frederik, a banker based in Zaltbommel , financed the purchase and setup of an empty factory building in Eindhoven, where the company started the production of carbon-filament lamps and other electro-technical products in 1892. This first factory has since been adapted and

1526-568: A paper that also suggested it is possible to multiply the capacity of a wireless link using what the author described as "layered space-time architecture." Greg Raleigh, V. K. Jones, and Michael Pollack founded Clarity Wireless in 1996, and built and field-tested a prototype MIMO system. Cisco Systems acquired Clarity Wireless in 1998. Bell Labs built a laboratory prototype demonstrating its V-BLAST (Vertical-Bell Laboratories Layered Space-Time) technology in 1998. Arogyaswami Paulraj founded Iospan Wireless in late 1998 to develop MIMO-OFDM products. Iospan

1635-410: A phenomenon in the physics of waves whereby a wave from a source travels to a detector via two or more paths and the two (or more) components of the wave interfere constructively or destructively. Multipath interference is a common cause of " ghosting " in analog television broadcasts and of fading of radio waves . The condition necessary is that the components of the wave remain coherent throughout

1744-550: A plan to split the company into two, separating the lighting business from the healthcare and consumer lifestyle divisions. It moved to complete this in March 2015 to an investment group for $ 3.3 billion. In February 2015, Philips acquired Volcano Corporation to strengthen its position in non-invasive surgery and imaging. In June 2016, Philips spun off its lighting division to focus on the healthcare division. In June 2017, Philips announced it would acquire US-based Spectranetics Corp,

1853-481: A radio signal to become too weak in certain areas to be received adequately. For this reason, this effect is also known as multipath interference or multipath distortion . Where the magnitudes of the signals arriving by the various paths have a distribution known as the Rayleigh distribution , this is known as Rayleigh fading . Where one component (often, but not necessarily, a line of sight component) dominates,

1962-416: A statistical detection problem, and addressed using a variety of techniques including zero-forcing, successive interference cancellation a.k.a. V-blast , Maximum likelihood estimation and recently, neural network MIMO detection. Such techniques commonly assume that the channel matrix H {\displaystyle \mathbf {H} } is known at the receiver. In practice, in communication systems,

2071-471: A task group in late 2003 to develop a wireless LAN standard delivering at least 100 Mbit/s of user data throughput. There were two major competing proposals: TGn Sync was backed by companies including Intel and Philips , and WWiSE was supported by companies including Airgo Networks, Broadcom , and Texas Instruments . Both groups agreed that the 802.11n standard would be based on MIMO-OFDM with 20 MHz and 40 MHz channel options. TGn Sync, WWiSE, and

2180-579: A third proposal (MITMOT, backed by Motorola and Mitsubishi ) were merged to create what was called the Joint Proposal. In 2004, Airgo became the first company to ship MIMO-OFDM products. Qualcomm acquired Airgo Networks in late 2006. The final 802.11n standard supported speeds up to 600 Mbit/s (using four simultaneous data streams) and was published in late 2009. Surendra Babu Mandava and Arogyaswami Paulraj founded Beceem Communications in 2004 to produce MIMO-OFDM chipsets for WiMAX . The company

2289-739: A wealth of information, which they later licensed to other companies. The first Philips shaver was introduced in 1939, and was simply called Philishave . In the US, it was called Norelco . The Philishave has remained part of the Philips product line-up until the present. On 9 May 1940, the Philips directors learned that the German invasion of the Netherlands was to take place the following day. Being prepared, Anton Philips and his son-in-law Frans Otten , as well as other Philips family members, fled to

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2398-418: Is a fundamental property that can be proved under almost any physical channel propagation model and with practical hardware that is prone to transceiver impairments. A textbook by A. Paulraj, R. Nabar and D. Gore has published an introduction to this area. There are many other principal textbooks available as well. There exists a fundamental tradeoff between transmit diversity and spatial multiplexing gains in

2507-409: Is achieved through waterfilling , that is where d 1 , … , d min ( N t , N r ) {\displaystyle d_{1},\ldots ,d_{\min(N_{t},N_{r})}} are the diagonal elements of D {\displaystyle \mathbf {D} } , ( ⋅ ) + {\displaystyle (\cdot )^{+}}

2616-424: Is called channel sounding or channel estimation . A known signal is sent to the mobile device that enables it to build a picture of the channel environment. The mobile device sends back the channel characteristics to the transmitter. The transmitter can then apply the correct phase and amplitude adjustments to form a beam directed at the mobile device. This is called a closed-loop MIMO system. For beamforming , it

2725-468: Is called multipath fading. In analog facsimile and television transmission , multipath causes jitter and ghosting, seen as a faded duplicate image to the right of the main image. Ghosts occur when transmissions bounce off a mountain or other large object, while also arriving at the antenna by a shorter, direct route, with the receiver picking up two signals separated by a delay. In radar processing, multipath causes ghost targets to appear, deceiving

2834-552: Is limited by the lesser of the number of antennas at the transmitter or receiver. Spatial multiplexing can be used without CSI at the transmitter, but can be combined with precoding if CSI is available. Spatial multiplexing can also be used for simultaneous transmission to multiple receivers, known as space-division multiple access or multi-user MIMO , in which case CSI is required at the transmitter. The scheduling of receivers with different spatial signatures allows good separability. Diversity coding techniques are used when there

2943-455: Is more accurately termed multi-user multiple-input single-output (MU-MISO). MIMO is often traced back to 1970s research papers concerning multi-channel digital transmission systems and interference (crosstalk) between wire pairs in a cable bundle: AR Kaye and DA George (1970), Branderburg and Wyner (1974), and W. van Etten (1975, 1976). Although these are not examples of exploiting multipath propagation to send multiple information streams, some of

3052-403: Is multi-stream beamforming , in the narrowest definition. In more general terms, it is considered to be all spatial processing that occurs at the transmitter. In (single-stream) beamforming, the same signal is emitted from each of the transmit antennas with appropriate phase and gain weighting such that the signal power is maximized at the receiver input. The benefits of beamforming are to increase

3161-434: Is no channel knowledge at the transmitter. In diversity methods, a single stream (unlike multiple streams in spatial multiplexing) is transmitted, but the signal is coded using techniques called space-time coding . The signal is emitted from each of the transmit antennas with full or near orthogonal coding. Diversity coding exploits the independent fading in the multiple antenna links to enhance signal diversity. Because there

3270-753: Is no channel knowledge, there is no beamforming or array gain from diversity coding. Diversity coding can be combined with spatial multiplexing when some channel knowledge is available at the receiver. Multi-antenna MIMO (or single-user MIMO) technology has been developed and implemented in some standards, e.g., 802.11n products. Third Generation (3G) (CDMA and UMTS) allows for implementing space-time transmit diversity schemes, in combination with transmit beamforming at base stations. Fourth Generation (4G) LTE And LTE Advanced define very advanced air interfaces extensively relying on MIMO techniques. LTE primarily focuses on single-link MIMO relying on Spatial Multiplexing and space-time coding while LTE-Advanced further extends

3379-400: Is required to adjust the phases and amplitude of each transmitter. In a beamformer optimized for spatial diversity or spatial multiplexing, each antenna element simultaneously transmits a weighted combination of two data symbols. Papers by Gerard J. Foschini and Michael J. Gans, Foschini and Emre Telatar have shown that the channel capacity (a theoretical upper bound on system throughput) for

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3488-457: Is studied in a sub-discipline called MIMO radar . MIMO technology can be used in non-wireless communications systems. One example is the home networking standard ITU-T G.9963 , which defines a powerline communications system that uses MIMO techniques to transmit multiple signals over multiple AC wires (phase, neutral and ground). In MIMO systems, a transmitter sends multiple streams by multiple transmit antennas. The transmit streams go through

3597-806: Is the ratio between transmit power and noise power (i.e., transmit SNR ). The optimal signal covariance Q = V S V H {\displaystyle \mathbf {Q} =\mathbf {VSV} ^{H}} is achieved through singular value decomposition of the channel matrix U D V H = H {\displaystyle \mathbf {UDV} ^{H}\,=\,\mathbf {H} } and an optimal diagonal power allocation matrix S = diag ( s 1 , … , s min ( N t , N r ) , 0 , … , 0 ) {\displaystyle \mathbf {S} ={\textrm {diag}}(s_{1},\ldots ,s_{\min(N_{t},N_{r})},0,\ldots ,0)} . The optimal power allocation

3706-425: Is time varying, and as such we have Very often, just one parameter is used to denote the severity of multipath conditions: it is called the multipath time , T M {\displaystyle T_{M}} , and it is defined as the time delay existing between the first and the last received impulses In practical conditions and measurement, the multipath time is computed by considering as last impulse

3815-438: Is transmitted from a different transmit antenna in the same frequency channel. If these signals arrive at the receiver antenna array with sufficiently different spatial signatures and the receiver has accurate CSI, it can separate these streams into (almost) parallel channels. Spatial multiplexing is a very powerful technique for increasing channel capacity at higher signal-to-noise ratios (SNR). The maximum number of spatial streams

3924-456: Is used as a museum. In 1895, after a difficult first few years and near-bankruptcy, the Philips's brought in Anton , Gerard's younger brother by sixteen years. Though he had earned a degree in engineering, Anton started work as a sales representative; soon, however, he began to contribute many important business ideas. With Anton's arrival, the family business began to expand rapidly, resulting in

4033-412: Is zero if its argument is negative, and μ {\displaystyle \mu } is selected such that s 1 + … + s min ( N t , N r ) = N t {\displaystyle s_{1}+\ldots +s_{\min(N_{t},N_{r})}=N_{t}} . If the transmitter has only statistical channel state information , then

4142-727: The Dutch East Indies (now Indonesia ), and later PHI broadcast in English and other languages to the Eastern hemisphere, while PCJJ broadcast in English, Spanish and German to the rest of the world. The international program Sundays commenced in 1928, with host Eddie Startz hosting the Happy Station show, which became the world's longest-running shortwave program. Broadcasts from the Netherlands were interrupted by

4251-605: The International Court of Arbitration ruled in favour of Philips, awarding compensation of € 135 million in the process. In April 2013, Philips announced a collaboration with Paradox Engineering for the realization and implementation of a "pilot project" on network-connected street-lighting management solutions. This project was endorsed by the San Francisco Public Utilities Commission (SFPUC). In 2013, Philips removed

4360-675: The Respironics brand), and Personal Health (manufacturing electric shavers , Sonicare electric toothbrushes and Avent childcare products). Philips has a primary listing on the Euronext Amsterdam stock exchange and is a component of the Euro Stoxx 50 stock market index . It has a secondary listing on the New York Stock Exchange . Acquisitions included Signetics and Magnavox . It also founded

4469-453: The compact cassette audio tape format in 1963, and it was wildly successful. Cassettes were initially used for dictation machines for office typing stenographers and professional journalists. As their sound quality improved, cassettes would also be used to record sound and became the second mass media alongside vinyl records used to sell recorded music. Philips introduced the first combination portable radio and cassette recorder, which

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4578-422: The complex amplitude (i.e., magnitude and phase) of the generic received pulse. As a consequence, y ( t ) {\displaystyle y(t)} also represents the impulse response function h ( t ) {\displaystyle h(t)} of the equivalent multipath model. More in general, in presence of time variation of the geometrical reflection conditions, this impulse response

4687-622: The intersymbol interference that multipath propagation would cause. The ITU-T G.hn standard provides a way to create a high-speed (up to 1 gigabit per second) local area network using existing home wiring ( power lines , phone lines, and coaxial cables ). G.hn uses OFDM with a cyclic prefix to avoid ISI. Because multipath propagation behaves differently in each kind of wire, G.hn uses different OFDM parameters (OFDM symbol duration, guard interval duration) for each media. DSL modems also use orthogonal frequency-division multiplexing to communicate with their DSLAM despite multipath. In this case

4796-677: The mini-cassette , although it was not as successful as the Olympus microcassette . The mini-cassette became the predominant dictation medium up to the advent of fully digital dictation machines. Philips continued with computers through the early 1990s (see separate article: Philips Computers ). In 1972, Philips launched the world's first home videocassette recorder , in the UK, the N1500. Its relatively bulky video cassettes could record 30 minutes or 45 minutes. Later one-hour tapes were also offered. As

4905-568: The 2010s. On 5 December 2012, the antitrust regulators of the European Union fined Philips and several other major companies for fixing prices of TV cathode-ray tubes in two cartels lasting nearly a decade. On 29 January 2013, it was announced that Philips had agreed to sell its audio and video operations to the Japan-based Funai Electric for €150 million, with the audio business planned to transfer to Funai in

5014-565: The Dutch International Service. Some PCJ programs, such as Happy Station , continued on the new station. Philips was instrumental in the revival of the Stirling engine when, in the early 1930s, the management decided that offering a low-power portable generator would assist in expanding sales of its radios into parts of the world where mains electricity was unavailable and the supply of batteries uncertain. Engineers at

5123-545: The Dutch Philips Group bought out nearly a one-third share and took over the management of the German company Grundig . Also in 1984, Philips split off its activities on the field of photolithographic integrated circuit production equipment, the so-called wafer steppers, into a joint venture with ASM International , located in Veldhoven under the name ASML . Over the years, this new company has evolved into

5232-563: The German invasion in May 1940. The Germans commandeered the transmitters in Huizen to use for pro- Nazi broadcasts , some originating from Germany, others concerts from Dutch broadcasters under German control. In the early 1930s, Philips introduced the "Chapel", a radio with a built-in loudspeaker. Philips Radio was absorbed shortly after liberation when its two shortwave stations were nationalized in 1947 and renamed Radio Netherlands Worldwide ,

5341-639: The Japanese makers, whose tapes were significantly cheaper. Philips made one last attempt at a new standard for video recorders with the Video 2000 system, with tapes that could be used on both sides and had 8 hours of total recording time. As Philips only sold its systems on the PAL standard and in Europe, and the Japanese makers sold globally, the scale advantages of the Japanese proved insurmountable and Philips withdrew

5450-629: The Philips Radio factory in Eindhoven with few casualties among the Dutch workers and civilians. The Philips works in Eindhoven was bombed again by the RAF on 30 March 1943. Frits Philips , the son of Anton, was the only Philips family member to stay in the Netherlands. He saved the lives of 382 Jews by convincing the Nazis that they were indispensable for the production process at Philips. In 1943, he

5559-608: The Stirling engine for many years and asserted that modern materials and know-how should enable great improvements. Encouraged by their first experimental engine, which produced 16 W of shaft power from a bore and stroke of 30 mm × 25 mm , various development models were produced in a program which continued throughout World War II . By the late 1940s, the "Type 10" was ready to be handed over to Philips' subsidiary Johan de Witt in Dordrecht to be produced and incorporated into

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5668-683: The United States taking a large amount of the company capital with them. Operating from the US as the North American Philips Company , they managed to run the company throughout the war. At the same time, the company was moved (on paper) to the Netherlands Antilles to keep it out of German hands. On 6 December 1942, the British No. 2 Group RAF undertook Operation Oyster , which heavily damaged

5777-673: The V2000 system and joined the VHS Coalition. Philips had developed a LaserDisc early on for selling movies, but delayed its commercial launch for fear of cannibalizing its video recorder sales. Later Philips joined with MCA to launch the first commercial LaserDisc standard and players. In 1982, Philips teamed with Sony to launch the compact disc ; this format evolved into the CD-R , CD-RW , DVD and later Blu-ray , which Philips launched with Sony in 1997 and 2006 respectively. In 1984,

5886-446: The attention of engineers and mathematicians is how to use the multi-output signals at the receiver to recover the multi-input signals at the transmitter. In Shang, Sun and Zhou (2007), sufficient and necessary conditions are established to guarantee the complete recovery of the multi-input signals. Multipath propagation In radio communication , multipath is the propagation phenomenon that results in radio signals reaching

5995-401: The channel matrix and the noise vector, respectively. Referring to information theory , the ergodic channel capacity of MIMO systems where both the transmitter and the receiver have perfect instantaneous channel state information is where ( ) H {\displaystyle ()^{H}} denotes Hermitian transpose and ρ {\displaystyle \rho }

6104-559: The company started to manufacture other products, such as vacuum tubes . For this purpose the Van Arkel–de Boer process was invented. In 1924, Philips joined with German lamp trust Osram to form the Phoebus cartel . On 11 March 1927, Philips went on the air, inaugurating the shortwave radio station PCJJ (later PCJ) which was joined in 1929 by a sister station (Philips Omroep Holland-Indië, later PHI). PHOHI broadcast in Dutch to

6213-602: The company was housed in the Rembrandt Tower . In 2002, it moved to the Breitner Tower. Philips Lighting, Philips Research , Philips Semiconductors (spun off as NXP in September 2006), and Philips Design, are still based in Eindhoven. Philips Healthcare is headquartered in both Best, Netherlands (near Eindhoven) and Andover, Massachusetts , (north of Boston ). In 2000, Philips bought Optiva Corporation,

6322-507: The company's research lab carried out a systematic comparison of various power sources and determined that the almost forgotten Stirling engine would be most suitable, citing its quiet operation (both audibly and in terms of radio interference) and ability to run on a variety of heat sources (common lamp oil – "cheap and available everywhere" – was favored). They were also aware that, unlike steam and internal combustion engines, virtually no serious development work had been carried out on

6431-501: The competition came from Sony 's Betamax and the VHS group of manufacturers, Philips introduced the N1700 system which allowed double-length recording. For the first time, a 2-hour movie could fit onto one video cassette. In 1977, the company unveiled a special promotional film for this system in the UK, featuring comedy writer and presenter Denis Norden . The concept was quickly copied by

6540-539: The design to multi-user MIMO. In wireless local area networks (WLAN), the IEEE 802.11n (Wi-Fi), MIMO technology is implemented in the standard using three different techniques: antenna selection, space-time coding and possibly beamforming. Spatial multiplexing techniques make the receivers very complex, and therefore they are typically combined with orthogonal frequency-division multiplexing (OFDM) or with orthogonal frequency-division multiple access (OFDMA) modulation, where

6649-591: The distance (in Hz) between two consecutive valleys (or two consecutive peaks), is roughly inversely proportional to the multipath time. The so-called coherence bandwidth is thus defined as For example, with a multipath time of 3 μs (corresponding to a 1 km of added on-air travel for the last received impulse), there is a coherence bandwidth of about 330 kHz. [REDACTED]  This article incorporates public domain material from Federal Standard 1037C . General Services Administration . Archived from

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6758-930: The end of 2015. The first 4G cellular standard was proposed by NTT DoCoMo in 2004. Long term evolution (LTE) is based on MIMO-OFDM and continues to be developed by the 3rd Generation Partnership Project (3GPP). LTE specifies downlink rates up to 300 Mbit/s, uplink rates up to 75 Mbit/s, and quality of service parameters such as low latency. LTE Advanced adds support for picocells, femtocells, and multi-carrier channels up to 100 MHz wide. LTE has been embraced by both GSM/UMTS and CDMA operators. The first LTE services were launched in Oslo and Stockholm by TeliaSonera in 2009. As of 2015, there were more than 360 LTE networks in 123 countries operational with approximately 373 million connections (devices). MIMO can be sub-divided into three main categories: precoding , spatial multiplexing (SM), and diversity coding . Precoding

6867-708: The ergodic channel capacity will decrease as the signal covariance Q {\displaystyle \mathbf {Q} } can only be optimized in terms of the average mutual information as The spatial correlation of the channel has a strong impact on the ergodic channel capacity with statistical information. If the transmitter has no channel state information it can select the signal covariance Q {\displaystyle \mathbf {Q} } to maximize channel capacity under worst-case statistics, which means Q = 1 / N t I {\displaystyle \mathbf {Q} =1/N_{t}\mathbf {I} } and accordingly Depending on

6976-482: The first large (42-inch) commercially available flat-panel TV, using Fujitsu plasma displays. In 1998, looking to spur innovation, Philips created an Emerging Businesses group for its Semiconductors unit, based in Silicon Valley . The group was designed to be an incubator where promising technologies and products could be developed. The move of the headquarters to Amsterdam was completed in 2001. Initially,

7085-413: The first one which allows receiving a determined amount of the total transmitted power (scaled by the atmospheric and propagation losses), e.g. 99%. Keeping our aim at linear, time invariant systems, we can also characterize the multipath phenomenon by the channel transfer function H ( f ) {\displaystyle H(f)} , which is defined as the continuous time Fourier transform of

7194-406: The founding of Philips Metaalgloeilampfabriek N.V. (Philips Metal Filament Lamp Factory Ltd.) in Eindhoven in 1908, followed in 1912, by the foundation of Philips Gloeilampenfabrieken N.V. (Philips Lightbulb Factories Ltd.). After Gerard and Anton Philips changed their family business by founding the Philips corporation , they laid the foundations for the later multinational company. In the 1920s,

7303-519: The impulse response h ( t ) {\displaystyle h(t)} where the last right-hand term of the previous equation is easily obtained by remembering that the Fourier transform of a Dirac pulse is a complex exponential function, an eigenfunction of every linear system. The obtained channel transfer characteristic has a typical appearance of a sequence of peaks and valleys (also called notches ); it can be shown that, on average,

7412-515: The independent Philips Lighting N.V. was renamed Signify N.V. However, it continues to produce and market Philips-branded products such as Philips Hue color-changing LED light bulbs. In 2021, Philips Domestic Appliances was purchased by Hillhouse Capital for $ 4.4 billion. The company, now known as Versuni , continues to sell small appliances under the Philips brand under license. In 2022, Philips announced that Frans Van Houten , who had served as CEO for 12 years would be stepping down, after

7521-535: The latter half of 2013, and the video business in 2017. As part of the transaction, Funai was to pay a regular licensing fee to Philips for the use of the Philips brand. The purchase agreement was terminated by Philips in October because of breach of contract and the consumer electronics operations remained under Philips. Philips said it would seek damages for breach of contract in the US$ 200-million sale. In April 2016,

7630-600: The light takes 3 μs to cross a 1 km span). Thus, the received signal will be expressed by where N {\displaystyle N} is the number of received impulses (equivalent to the number of electromagnetic paths, and possibly very large), τ n {\displaystyle \tau _{n}} is the time delay of the generic n t h {\displaystyle n^{th}} impulse, and ρ n e j ϕ n {\displaystyle \rho _{n}e^{j\phi _{n}}} represent

7739-447: The maker of Sonicare electric toothbrushes . The company was renamed Philips Oral Healthcare and made a subsidiary of Philips DAP. In 2001, Philips acquired Agilent Technologies ' Healthcare Solutions Group (HSG) for EUR 2 billion. Philips created a computer monitors joint venture with LG called LG.Philips Displays in 2001. In 2001, after growing the unit's Emerging Businesses group to nearly $ 1 billion in revenue, Scott A. McGregor

7848-501: The mammography division of Sectra AB . Because net profit slumped 85 percent in Q3 2011, Philips announced a cut of 4,500 jobs to match part of an €800 million ($ 1.1 billion) cost-cutting scheme to boost profits and meet its financial target. In 2011, the company posted a loss of €1.3 billion, but earned a net profit in Q1 and Q2 2012, however the management wanted €1.1 billion cost-cutting which

7957-409: The mathematical techniques for dealing with mutual interference proved useful to MIMO development. In the mid-1980s Jack Salz at Bell Laboratories took this research a step further, investigating multi-user systems operating over "mutually cross-coupled linear networks with additive noise sources" such as time-division multiplexing and dually-polarized radio systems. Methods were developed to improve

8066-476: The multiple receive antennas and decodes the received signal vectors into the original information. A narrowband flat fading MIMO system is modeled as: where y {\displaystyle \mathbf {y} } and x {\displaystyle \mathbf {x} } are the receive and transmit vectors, respectively, and H {\displaystyle \mathbf {H} } and n {\displaystyle \mathbf {n} } are

8175-607: The original on 2022-01-22. Philips Koninklijke Philips N.V. ( lit.   ' Royal Philips ' ), commonly shortened to Philips , is a Dutch multinational conglomerate corporation that was founded in Eindhoven in 1891. Since 1997, its world headquarters have been situated in Amsterdam , though the Benelux headquarters is still in Eindhoven. The company gained its royal honorary title in 1998. Philips

8284-431: The original rationale for the set was disappearing. Approximately 150 of these sets were eventually produced. In parallel with the generator set, Philips developed experimental Stirling engines for a wide variety of applications and continued to work in the field until the late 1970s, though the only commercial success was the "reversed Stirling engine" cryocooler . However, they filed a large number of patents and amassed

8393-471: The outstanding shares of Respironics for US$ 66 per share, or a total purchase price of approximately €3.6  billion (US$ 5.1 billion) in cash. On 21 February 2008, Philips completed the acquisition of VISICU in Baltimore, Maryland, through the merger of its indirect wholly-owned subsidiary into VISICU. As a result of that merger, VISICU has become an indirect wholly-owned subsidiary of Philips. VISICU

8502-448: The performance of cellular radio networks and enable more aggressive frequency reuse in the early 1990s. Space-division multiple access (SDMA) uses directional or smart antennas to communicate on the same frequency with users in different locations within range of the same base station. An SDMA system was proposed by Richard Roy and Björn Ottersten , researchers at ArrayComm , in 1991. Their US patent (No. 5515378 issued in 1996) describes

8611-680: The problems created by a multi-path channel are handled efficiently. The IEEE 802.16e standard incorporates MIMO-OFDMA. The IEEE 802.11n standard, released in October 2009, recommends MIMO-OFDM. MIMO is used in mobile radio telephone standards such as 3GPP and 3GPP2 . In 3GPP, High-Speed Packet Access plus (HSPA+) and Long Term Evolution (LTE) standards take MIMO into account. Moreover, to fully support cellular environments, MIMO research consortia including IST-MASCOT propose to develop advanced MIMO techniques, e.g., multi-user MIMO (MU-MIMO). MIMO wireless communications architectures and processing techniques can be applied to sensing problems. This

8720-465: The quality of communications. The errors are due to intersymbol interference (ISI). Equalizers are often used to correct the ISI. Alternatively, techniques such as orthogonal frequency division modulation and rake receivers may be used. In a Global Positioning System receiver , multipath effects can cause a stationary receiver's output to indicate as if it were randomly jumping about or creeping. When

8829-417: The quality of the signal channel is also critical. A channel emulator can simulate how a device performs at the cell edge, can add noise or can simulate what the channel looks like at speed. To fully qualify the performance of a receiver, a calibrated transmitter, such as a vector signal generator (VSG), and channel emulator can be used to test the receiver under a variety of different conditions. Conversely,

8938-491: The radar receiver . These ghosts are particularly bothersome since they move and behave like the normal targets (which they echo), and so the receiver has difficulty in isolating the correct target echo. These problems can be minimized by incorporating a ground map of the radar's surroundings and eliminating all echoes which appear to originate below the ground or above a certain height (altitude). In digital radio communications (such as GSM ) multipath can cause errors and affect

9047-871: The receive antenna array based on differences in "directions-of-arrival." Paulraj was awarded the prestigious Marconi Prize in 2014 for "his pioneering contributions to developing the theory and applications of MIMO antennas. ... His idea for using multiple antennas at both the transmitting and receiving stations – which is at the heart of the current high speed WiFi and 4G mobile systems – has revolutionized high speed wireless." In an April 1996 paper and subsequent patent, Greg Raleigh proposed that natural multipath propagation can be exploited to transmit multiple, independent information streams using co-located antennas and multi-dimensional signal processing. The paper also identified practical solutions for modulation ( MIMO-OFDM ), coding, synchronization, and channel estimation. Later that year (September 1996) Gerard J. Foschini submitted

9156-407: The received signal gain – by making signals emitted from different antennas add up constructively – and to reduce the multipath fading effect. In line-of-sight propagation , beamforming results in a well-defined directional pattern. However, conventional beams are not a good analogy in cellular networks, which are mainly characterized by multipath propagation . When the receiver has multiple antennas,

9265-406: The receiver, due to the presence of the multiple electromagnetic paths, more than one pulse will be received, and each one of them will arrive at different times. In fact, since the electromagnetic signals travel at the speed of light , and since every path has a geometrical length possibly different from that of the other ones, there are different air travelling times (consider that, in free space ,

9374-411: The receiving antenna by two or more paths. Causes of multipath include atmospheric ducting , ionospheric reflection and refraction , and reflection from water bodies and terrestrial objects such as mountains and buildings. When the same signal is received over more than one path, it can create interference and phase shifting of the signal. Destructive interference causes fading ; this may cause

9483-434: The reflections may be caused by mixed wire gauges , but those from bridge taps are usually more intense and complex. Where OFDM training is unsatisfactory, bridge taps may be removed. The mathematical model of the multipath can be presented using the method of the impulse response used for studying linear systems . Suppose you want to transmit a single, ideal Dirac pulse of electromagnetic power at time 0, i.e. At

9592-430: The sale of its Assembléon subsidiary which made pick-and-place machines for the electronics industry. Philips made several acquisitions during 2011, announcing on 5 January 2011 that it had acquired Optimum Lighting, a manufacturer of LED based luminaires. In January 2011, Philips agreed to acquire the assets of Preethi, a leading India-based kitchen appliances company. On 27 June 2011, Philips acquired Sectra Mamea AB,

9701-439: The same time, North American Philips was formally dissolved, and a new corporate division was formed in the US with the name Philips Electronics North America Corp. In 1997, the company officers decided to move the headquarters from Eindhoven to Amsterdam along with the corporate name change to Koninklijke Philips Electronics N.V., the latter of which was finalized on 16 March 1998. In 1997, Philips introduced at CES and CeBIT

9810-547: The slogan "Let's make things better" in favor of a new one: "Sense and Simplicity". In December 2005, Philips announced its intention to sell or demerge its semiconductor division. On 1 September 2006, it was announced in Berlin that the name of the new company formed by the division would be NXP Semiconductors . On 2 August 2006, Philips completed an agreement to sell a controlling 80.1% stake in NXP Semiconductors to

9919-542: The statistical properties of the channel, the ergodic capacity is no greater than min ( N t , N r ) {\displaystyle \min(N_{t},N_{r})} times larger than that of a SISO system. A fundamental problem in MIMO communication is estimating the transmit vector, x {\displaystyle \mathbf {x} } , given the received vector, y {\displaystyle \mathbf {y} } . This can be posed as

10028-430: The transmit beamforming cannot simultaneously maximize the signal level at all of the receive antennas, and precoding with multiple streams is often beneficial. Precoding requires knowledge of channel state information (CSI) at the transmitter and the receiver. Spatial multiplexing requires MIMO antenna configuration. In spatial multiplexing, a high-rate signal is split into multiple lower-rate streams and each stream

10137-532: The transmitter sends a Pilot signal and the receiver learns the state of the channel (i.e., H {\displaystyle \mathbf {H} } ) from the received signal Y {\displaystyle Y} and the Pilot signal X {\displaystyle X} . Recently, there are works on MIMO detection using Deep learning tools which have shown to work better than other methods such as zero-forcing. MIMO signal testing focuses first on

10246-413: The transmitter's performance under a number of different conditions can be verified using a channel emulator and a calibrated receiver, such as a vector signal analyzer (VSA). Understanding the channel allows for manipulation of the phase and amplitude of each transmitter in order to form a beam. To correctly form a beam, the transmitter needs to understand the characteristics of the channel. This process

10355-458: The transmitter/receiver system. The random phases of the sub-carrier signals can produce instantaneous power levels that cause the amplifier to compress, momentarily causing distortion and ultimately symbol errors. Signals with a high PAR ( peak-to-average ratio ) can cause amplifiers to compress unpredictably during transmission. OFDM signals are very dynamic and compression problems can be hard to detect because of their noise-like nature. Knowing

10464-419: The unit is moving the jumping or creeping may be hidden, but it still degrades the displayed accuracy of location and speed. Multipath propagation is similar in power line communication and in telephone local loops . In either case, impedance mismatch causes signal reflection . High-speed power line communication systems usually employ multi-carrier modulations (such as OFDM or wavelet OFDM) to avoid

10573-433: The whole extent of their travel. The interference will arise owing to the two (or more) components of the wave having, in general, travelled a different length (as measured by optical path length – geometric length and refraction (differing optical speed)), and thus arriving at the detector out of phase with each other. The signal due to indirect paths interferes with the required signal in amplitude as well as phase which

10682-554: The word "Electronics" from its name – becoming Royal Philips N.V. On 13 November 2013, Philips unveiled its new brand line "Innovation and You" and a new design of its shield mark. The new brand positioning is cited by Philips to signify company's evolution and emphasize that innovation is only meaningful if it is based on an understanding of people's needs and desires. On 28 April 2014, Philips agreed to sell their Woox Innovations subsidiary (consumer electronics) to Gibson Brands for $ US135 million. On 23 September 2014, Philips announced

10791-428: The world's leading manufacturer of chip production machines at the expense of competitors like Nikon and Canon . Philips partnered with Sony again later to develop a new "interactive" disc format called CD-i , described by them as a "new way of interacting with a television set". Philips created the majority of CD-i compatible players. After low sales, Philips repositioned the format as a video game console , but it

10900-585: Was acquired by Broadcom in 2010. WiMAX was developed as an alternative to cellular standards, is based on the 802.16e standard, and uses MIMO-OFDM to deliver speeds up to 138 Mbit/s. The more advanced 802.16m standard enables download speeds up to 1 Gbit/s. A nationwide WiMAX network was built in the United States by Clearwire , a subsidiary of Sprint-Nextel , covering 130 million points of presence (PoPs) by mid-2012. Sprint subsequently announced plans to deploy LTE (the cellular 4G standard) covering 31 cities by mid-2013 and to shut down its WiMAX network by

11009-472: Was acquired by Intel in 2003. Neither Clarity Wireless nor Iospan Wireless shipped MIMO-OFDM products before being acquired. MIMO technology has been standardized for wireless LANs , 3G mobile phone networks, and 4G mobile phone networks and is now in widespread commercial use. Greg Raleigh and V. K. Jones founded Airgo Networks in 2001 to develop MIMO-OFDM chipsets for wireless LANs. The Institute of Electrical and Electronics Engineers ( IEEE ) created

11118-486: Was an increase from €800 million and may cut another 2,200 jobs until end of 2014. In March 2012, Philips announced its intention to sell, or demerge its television manufacturing operations to TPV Technology . After two decades in decline, Philips went through a major restructuring, shifting its focus from electronics to healthcare. Particularly from 2011 when a new CEO was appointed, Frans van Houten. The new health and medical strategy have helped Philips to thrive again in

11227-530: Was established as a joint venture between Philips, the Taiwan government and other private investors. In 1990, the newly appointed CEO, Jan Timmer, decided to sell off all businesses that dealt with computers which meant the end of Philips Data Systems as well as other computer activities. In 1991, the businesses were acquired by Digital Equipment Corporation. In 1991, the company's name was changed from N.V. Philips Gloeilampenfabrieken to Philips Electronics N.V. At

11336-428: Was founded by Gerard Philips and his father Frederik, with their first products being light bulbs . Through the 20th century, it grew into one of the world's largest electronics conglomerates , with global market dominance in products ranging from kitchen appliances and electric shavers to light bulbs , televisions , cassettes , and compact discs (both of which were invented by Philips). At one point, it played

11445-591: Was held at the internment camp for political prisoners at Vught for several months because a strike at his factory reduced production. For his actions in saving the hundreds of Jews, he was recognized by Yad Vashem in 1995 as a " Righteous Among the Nations ". After the war, the company was moved back to the Netherlands, with their headquarters in Eindhoven . In 1949, the company began selling television sets . In 1950, it formed Philips Records , which eventually formed part of PolyGram in 1962. Philips introduced

11554-399: Was marketed as the "radio recorder", and is now better known as the boombox . Later, the cassette was used in telephone answering machines , including a special form of cassette where the tape was wound on an endless loop. The C-cassette was used as the first mass storage device for early personal computers in the 1970s and 1980s. Philips reduced the cassette size for professional needs with

11663-607: Was named the new president and CEO of Philips Semiconductors. McGregor's appointment completed the company's shift to having dedicated CEOs for all five of the company's product divisions, which would in turn leave the Board of Management to concentrate on issues confronting the Philips Group as a whole. In February 2001 Philips sold its remaining interest in battery manufacturing to its then partner Matsushita (which itself became Panasonic in 2008). In 2004, Philips abandoned

11772-480: Was soon discontinued after being heavily criticized amongst the gaming community. In the 1980s, Philips's profit margin dropped below 1 percent, and in 1990 the company lost more than US$ 2 billion (biggest corporate loss in Dutch history). Troubles for the company continued into the 1990s as its status as a leading electronics company was swiftly lost. In 1985, Philips was the largest founding investor in TSMC which

11881-560: Was the creator of the eICU concept of the use of Telemedicine from a centralized facility to monitor and care for ICU patients. The Philips physics laboratory was scaled down in the early 21st century, as the company ceased trying to be innovative in consumer electronics through fundamental research . In 2010, Philips introduced the Airfryer brand of convection oven at the IFA Berlin consumer electronics fair. Philips announced

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