MIMO wireless channel
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29-12-2009, 03:39 PM
i need a seminar and presentation report on MIMO wireless technology.pls provide me this report immediately.
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30-12-2009, 07:33 PM
MIMO means Multiple Input Multiple Output wireless communication systems.Recently, systems that use multiple antennas at the transmitter and the receiver were developed. Such systems are known as multiple input multiple output (MIMO) systems. The advantages are
budget / spatial diversity improvement and throughput improvement
from spatial multiplexing.
Spatial diversity: the fact that the probability of having
all antennas at bad locations is lowered as the number of
Keywords Link budget improvement:
the signals from the various antennas can be combined
signal stronger than any of the individual signals.
spatial multiplexing : A way to exploit rich spatial dimensionality : signals received at different antennas are combinations of the
transmitted data streams.DSP algorithms can be used to recover the original data streams .
Spatial multiplexing can be either open-loop or
closed-loop. In open-loop , different streams are
simply transmitted from different antennas.
In closed-loop spatial every stream is transmitted from all of the antennas
using weights computed from the channel estimation.
spatial multiplexingimproves peak data rates and
increases spectrum efficiency.
multiple RF and baseband chains are required. The block daigram consists of
FEC block ,StreamSplit block ,a Spatial Mapping block, iFFTs and different antennas.
-Higher power consumption.
- thermal and
battery life constraints limit tolerable power consumption
- tolerable cost impacted by market factor
Full seminar and presentation report:
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MIMO TECHNOLOGY.docx (Size: 310.79 KB / Downloads: 151)
Topic: MIMO TECHNOLOGY
Ramesh babu Vallabhaneni
Article Name: MULTIPLE I.P MULTIPLE O.P TECHNOLOGY.
In the present era of communication technology 3rd generation (3G) i.e. it is
optimally focused on using a single interface number and an advanced core network. The
main service component of 3G technology is quality and reliable internet data traffic.
The research & development (R &D) is already aiming at Fourth-Generation(4G).
This paper MULTIPLE INPUT MULTIPLE OUTPUT TECHNOLOGY. In
this paper covers the both advantage & disadvantage 3G, and also deals about fading
and what are promises and limitations of MIMO TECHNOLOGY.
Communication is one of the most fundamental and essential activity in every walk of
human life in the modern society, without which human kind cannot survive. Human
communication took a big leap when long distance electrical communication
technologies like Telephony and Telegraphy were invented in the 19th Century. This truly
lead to the communication revolution which Marjory contributed to the overall
development of human kind, by removing the traditional barriers of the language and the
The Basic Components of a electronic communication system are shown in fig.
Here in this content discus only for channel. The channel which can allows the
signal from TX to RX communication channels are of two type i.e. guided media &
If any physical connection is there b/w the transmitter and received thus type of media is
called guided media.
Ex:- Land to Land Telephone System.
If there is no physical connection b/w the transiting and received is called unguided
Ex:- Cellular, Wireless.
Here deals the advanced wireless system i.e. MULTIPLE INPUT MULTIPLE
The human acoustical communication has one important feature; For the purpose
of communication, the address of the user is unique and one. If my name is ramesh
anybody will call me by ramesh at any time, anywhere and for any communication.
This is not the case in todayâ„¢s telephony, mobile or computer network. Your telephone
number will be different from city to city, your mobile number will be different from
network to network, and your e- mail address in Ëœvsnlâ„¢ will be different from that in
Technological trends follow the natural paths. We invented aircrafts to fly like
birds. Computers are being at tempted to be as brainy as humans. In the same way, the
communication technology is going to be human- like but without limitation of coverage
area. So the future will see a single number for a person for communication World over.
The future communication aims at becoming all-wireless and mobile supporting
any communication (Voice, Video, Data, Images, Pictures, Graphics, etc) anywhere, any
time and for anybody with a single unique identification number(UTN, Universal
Telecommunication Number) of a person service(PCS) and may be supported by the
personal communication network (PCN)- a global wireless and mobile network.
Trends in Wireless and Mobile Technology:-
Last few years have seen rapid development of wireless-technologies. The stage is set for
third- generation (3G) technology and R & D is already aiming at fourth- generation (4G)
technology(see Figs 1 and 2).
2G technology for mobile communication organized during 1990â„¢s and it
revolved around GSM mainly for voice communication. It was focused on voice services
with circuit switching, whereas the current 2.5 G technology is focused on circuit
switched voice service and packet-switched data service.
Seamless Coverage &
Anytime and Any
TOWARDS WIRELESS COMMUNICATION SOCIETY
MULTIMEDIA CONTENT, HIGH BIT RATE AND IP TRANSPORT
Fig:1 PCN evolution/migration
The 3G technology is optimally focused on using a single interface number and an
advanced core network.
1. Anywhere and anytime mobile connection with low-cost and flexible handheld
2. Wireless data access, particularly with wireless Interest connection. This was
motivated by the exponential growth of Internet access.
3. High-speed multimedia or broadband services, causing shift from voice-oriented
services to Internet access(both data and voice, particularly with VoIP
technology), Video, Music, Graphics and other multimedia services.
4. Global roaming to support global communication.
5. Flexible network to support existing and future requirements.
The 2G technology offered quite satisfactory voice communication service, but
with growing data traffic, the 3G technology has mainly targeted data services,
particularly the Internet traffic. Thus the main service component of the 3G
technology is quality and reliable Internet data traffic.
Major Challenges before the implementation of 3G are:
1. Slow production of 3G mobile phones and devices.
2. Wireless Internet for exponentially growing users will be difficult to implement
until IPv6 is implemented.
3. Global roaming with a single number as proposed in the PCN is yet to be
4. Fixed- line access technologies like ADSL offering high data rates of 12 Mbps, as
well as IEEE 802.11b WLAN in Wireless local data interface, are giving a tough
5. The devices are still struggling with limited processing powers of
microprocessors, small display with limited resolution, limited battery life, limited
memory size, etc.
Comprehensive, broadband, integrated mobile communication will step forward into all-
mobile 4G services and communication. The 4G technologies will be a migration from
the other generations of mobile services to overcome the limitation of boundary and
achieve total integration.
The 4G systems will be developed to provide high-speed transmission, next- generation
Internet support (IPv6, VoIP aand IP), high-capacity, seamless integrated services and
coverage, utilization of higher frequency, lower system cost, seamless personal mobility,
mobile multimedia(standards), efficient s p e c t rum use, quality of service(QoS),
reconfigurable network and end-to-end IP systems.
Wireless technologies are not free from problems like limitation of the available
frequency spectrum, fading and multipath fading. Fading results in sudden drop of signal
power in the receiver. Multipath fading results when the transmitted signal bounces off
objects like buildings, office cabinets and hills, creating multiple paths for the signal to
reach the receiver. The same transmitted signal that follows the different paths reaches
the receiver at different times with different phases.
Added together, the several incidences of the same signal with different phases
and amplitudes may cancel each other, causing signal less or drop of signal power.
The expectations from future wireless mobile networks are high data rate, higher
network capacity, better quality of service and lower probability of call drop, With
increasing data rates, the problem of multipath fading becomes severe.
Multipath fading (Fig.3) may be delay spread, short-term fading, long-term fading
and Doppler effect. Delay spread results in spreading of the transmitted pulse on the time
axis and even in generation of multiple low-amplitude pulse trains. It occurs in fixed
The receiver may not adapt to the changes. This degrades the service quality.
Short-term fading occurs over short time duration.
Long-term fading results in decreased received power over long time/distance; as
time increase, the moving receiver usually goes farther away,
The Doppler effect occurs in fast moving mobiles. It results in shift of the
MIMO Technology :
Wireless channels input and output modulated signals. For the purpose of modulation ,
the two basic things considered are frequency and time. The frequency plan and the time
plan use bits per hertzâ„¢ and Ëœbits per secondâ„¢ as measures for data rate transportation. A
new dimensions to upgrade the data transport rate is spatial dimension. This is the basic
idea behind multiple-input multiple-output (MIMO) technology.
MIMO technology may be seen as an upgrade of single- input multiple-output
(SIMO) and multiple- input single-output (MISO) technologies (Fig. 4) All three
technologies, namely, SIMO, MISO and MIMO, are based on the philosophy of using
Ëœdisadvantages for achieving gainsâ„¢. These use multiple paths (the sources of fading)for
increasing the data rate, throughput and reliability. Multiple paths are used by multiple
transmit antennae and multiple receive antennae. This deviation form SISO brings all
gains for SIMO, MISO and finally MIMO.
Multiple antennae at one end, either at the transmitter or at the receiver, were in
use long ago. The then use of multiple antennae aimed at beam formatting and spatial
diversity, which are mainly used to increase the signal-to-noise ratio. The improved
signal-to-noise ratio decreases the bit error rate.
In fact, if SIMO and MISO achieve gains by multiple antennae at receivers and
transmitters, respectively, multiple antennae both at the transmitter and the receiver are
supposed to multiple the gain. In other words, we can say that MIMO=MISO+SIMO.
The use of multiple antennae adds a new dimension to the digital communication
technology-the basis of 3G and 4G. The natural dimension of digital technology is time.
Added with that, MIMO offers a new space-time axis to digital technology. MIMO is
thus often termed as Ëœspace-time wirelessâ„¢ or Ëœsmart antennaeâ„¢. Of course, it is the
improved extension of smart antennae. Digital MIMO is also called Ëœvolume-to-volume
wireless linksâ„¢ as it offers parallel bit pipes between the transmitter and the receiver.
MIMO technology promises higher data rate, higher quality of service and better
reliability by exploiting antenna arrays as both the transmitter and the receiver. Signals at
both the sides (transmitter and receiver) are mixed such that they either generate multiple
parallel, spatial bit-pipes and/or add diversity to decrease the bit-error rate.
Diversity helps in selecting the clearest signal out of many signals, resulting in
lower bit-error rate. Multiple bit-pipes effectively increase the data rate(quantitative
improvement), where as the reduced bit-error rate improves the quality of service,
through-put and reliability (qualitative improvement). MIMO creates benefits beyond the
diversity of multiple antennae at one end only. Thus while qualitative improvements,
SIMO and MISO each offer only the qualitative improvement.
By spreading the transmitted signal over multiple paths, the MIMO technology
increases the chances of signal reception at the receiver. It also increases the range of
In Fig.4, MIMO covers all the three base regions of conventional cellular
telephony. The transmitter can adjust power and phase of the signal fed to antennae,
which allows the best transmission quality.
Multipath fading causes distortion by scrambling different copies of signals
reaching the receiver via multipaths on bouncing off the objects. Then how do the
multipath signals work in MIMO? Proper algorithms are used at both the transmitter and
the receiver to analyze the signal received form different paths and different antennae of
the array. Proper spacing of the antennae and signal analysis via a matrix manipulation
technology that cross-correlates the signals are the requirements of the MIMO
Not Without Limitations:
Complex algorithm and design are required for operation of multiple antennae. This will
make the handset and the other mobile devices costlier.
For implementation of the MIMO technology, R & D is required in his model,
signal processing approaches, and information theory for coding and capacity. The
design of MIMO networks, both fixed and mobile wireless, needs to optimally consider
the CDMA,TDMA and FDMA techniques and medium-access control protocols. MIMO
chips, products and systems are expected to hit the market with three years.
Though hopes are running high, it has been found that for some environments the
capacity of MIMO system is low even for uncorrelated signals. The effect is known as
More recently, the new wireless applications have rapidly evolved to radically
transform the World into a true global village, providing new means interaction on the
basis of ANY WHERE, ANY ONE, ANY TIME and ANY SERIVCE. Today we
witness mobile telephony, mobile internet, mobile personal communication and
integrated multimedia information networks, rapidly deployed to reach every nook and
corner of the society so called information society serving the needs of modern
information hungry society.
It is difficult to image what happens if the entire telecom infrastructure fails for a
couple of minutes. Truly speaking, telecom networks are the basic pillars of the modern
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HISTORY OF MIMO TECHNOLOGY
In radio, multiple-input and multiple-output, or MIMO (commonly pronounced my-moh or me-moh), is the use of multiple antennas at both the transmitter and receiver to improve communication performance. It is one of several forms of smart antenna technology.
MIMO technology has attracted attention in wireless communications, because it offers significant increases in data throughput and link range without additional bandwidth or transmit power. It achieves this by higher spectral efficiency (more bits per second per hertz of bandwidth) and link reliability or diversity (reduced fading). Because of these properties, MIMO is a current theme of international wireless research.
The increasing demand for capacity in wireless systems has motivated considerable research aimed at achieving higher throughput on a given bandwidth. One important recent discovery shows that in a multipath environment, the use of space-time coding with multiple antennas on both ends of the link can increase the capacity of the wireless channel.
Assessing the performance of these algorithms requires detailed understanding of multiple-input multiple-output (MIMO) channels as well as models that capture their complex spatial behavior. In this work, we discuss data from an experimental platform designed to measure the transfer matrix for indoor MIMO channels. The data is used to demonstrate the effect of polarization and array size on the achievable capacity for MIMO architectures. A propagation-based statistical model is shown to provide results that match closely with measured observations.
The earliest ideas in this field go back to work by A.R. Kaye and D.A. George (1970) and W. van Etten (1975, 1976). Jack Winters and Jack Salz at Bell Laboratories published several papers on beam forming related applications in 1984 and 1986.
Arogyaswami Paulraj and Thomas Kailath proposed the concept of spatial multiplexing (SM) using MIMO in 1993. Their US Patent No. 5,345,599 on Spatial Multiplexing issued 1994 emphasized applications to wireless broadcast.
In 1996, Greg Raleigh and Gerard J. Foschini refined new approaches to MIMO technology, considering a configuration where multiple transmit antennas are co-located at one transmitter to improve the link throughput effectively. Bell Labs was the first to demonstrate a laboratory prototype of spatial multiplexing in 1998, where spatial multiplexing is a principal technology to improve the performance of MIMO communication systems.
See also: MIMO technology in WiMAX and MIMO technology in 3G mobile standards
In the commercial arena, Iospan Wireless Inc. developed the first commercial system in 2001 that used MIMO with Orthogonal frequency-division multiple access technology (MIMO-OFDMA). Iospan technology supported both diversity coding and spatial multiplexing. In 2005, Airgo Networks had developed an IEEE 802.11n precursor implementation based on their patents on MIMO. Following that in 2006, several companies (including at least Broadcom, Intel, and Marvell) have fielded a MIMO-OFDM solution based on a pre-standard for 802.11n WiFi standard. Also in 2006, several companies (Beceem Communications, Samsung, Runcom Technologies, etc.) have developed MIMO-OFDMA based solutions for IEEE 802.16e WiMAX broadband mobile standard. All upcoming 4G systems will also employ MIMO technology. Several research groups have demonstrated over 1 Gbit/s prototypes.
2. INTRODUCTION OF MIMO TECHNOLGY
In radio, multiple-input and multiple-output, or MIMO (commonly pronounced my-moh or me-moh), is the use of multiple antennas at both the transmitter and receiver to improve communication performance. It is one of several forms of smart antenna technology. Note that the terms input and output refer to the radio channel carrying the signal, not to the devices having antennas.
MIMO technology has attracted attention in wireless communications, because it offers significant increases in data throughput and link range without additional bandwidth or transmit power. It achieves this by higher spectral efficiency (more bits per second per hertz of bandwidth) and link reliability or diversity (reduced fading). Because of these properties, MIMO is an important part of modern wireless communication standards such as IEEE 802.11n (Wifi), 4G, 3GPP Long Term Evolution, WiMAX and HSPA+.
Fig. 1 Understanding of SISO, SIMO, MISO and MIMO (note that the terms input and output refer to the radio channel carrying the signal, not to the devices having antennas)
High data rate wireless communications, nearing 1-Gb/s transmission rates, is of interest in emerging wireless local area networks and home audio/visual networks. Designing very high speed wireless links that offer good quality-of-service and range capability in non-line-of-sight (NLOS) environments constitutes a significant research and engineering challenge. Ignoring fading in NLOS environments, we can, in principle, meet the 1-Gb/s data rate requirement.
With a single-transmit single-receive antenna wireless system if the product of bandwidth (measured in hertz) and spectral efficiency (measured in bits per second per hertz) is equal to 10 . As we shall outline in this paper, a variety of cost, technology and regulatory constraints make such a brute force solution unattractive if not impossible. The use of multiple antennas at transmitter and receiver, popularly known as multiple-input multiple-output (MIMO) wireless is an emerging cost-effective technology that offers substantial leverages in making 1-Gb/s wireless links a reality. This paper provides an overview of MIMO wireless technology covering
channel models, performance limits, coding, and transceiver design
Digital communication using MIMO (multiple-input multiple-output) or also called volume to volume wireless links is emerging as one of the most promising research areas in wireless communications. In wireless MIMO the transmitting end as well as the receiving end is equipped with multiple antenna elements, as such MIMO can be viewed as an extension of the very popular ‘smart antennas’. In MIMO though the transmit antennas and receive antennas are jointly combined in such a way that the quality (Bit Error Rate) or the rate (Bit/Sec) of the communication is improved. At the system level, careful design of MIMO signal processing and coding algorithms can help increase dramatically capacity and coverage and thus can improve the economics of network deployment for operators. Today, MIMO wireless is widely recognized as one of three or four key technologies in the forthcoming high-speed high-spectrum efficiency wireless networks (4G, and to some extent 3G). Applications also exist in fixed wireless.
Progress in MIMO research poses strong scientific challenges in the areas of modeling (of mobile space-time wireless channels), information theory (coding, channel capacity and other bounds on information transfer rates), signal processing (signaling and modulation design, receiver algorithms), and finally the design of the wireless fixed or mobile networks that will incorporate those MIMO links in order to maximize their gain. More specifically, joint design of sensible multiple access solutions (CDMA, OFDMA, TDMA and variants) as well as medium access (MAC) protocol for wireless MIMO is challenging.
3. Functions of MIMO
MIMO can be sub-divided into three main categories, preceding, spatial multiplexing or SM, and diversity coding.
Precoding is multi-stream beam forming, in the narrowest definition. In more general terms, it is considered to be all spatial processing that occurs at the transmitter. In (single-layer) beam forming, the same signal is emitted from each of the transmit antennas with appropriate phase (and sometimes gain) weighting such that the signal power is maximized at the receiver input. The benefits of beam forming are to increase the received signal gain, by making signals emitted from different antennas add up constructively, and to reduce the multipath fading effect. In the absence of scattering, beam forming results in a well defined directional pattern, but in typical cellular conventional beams are not a good analogy. When the receiver has multiple antennas, the transmit beam forming cannot simultaneously maximize the signal level at all of the receive antennas, and preceding with multiple streams is used. Note that preceding requires knowledge of channel state information (CSI) at the transmitter.
Spatial multiplexing requires MIMO antenna configuration. In spatial multiplexing, a high rate signal is split into multiple lower rate streams and each stream 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, the receiver 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 is limited by the lesser in the number of antennas at the transmitter or receiver. Spatial multiplexing can be used with or without transmit channel knowledge. Spatial multiplexing can also be used for simultaneous transmission to multiple receivers, known as space-division multiple access. By scheduling receivers with different spatial signatures, good separability can be assured.
Diversity Coding techniques are used when there 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 is no channel knowledge, there is no beam forming or array gain from diversity coding.
Spatial multiplexing can also be combined with preceding when the channel is known at the transmitter or combined with diversity coding when decoding reliability is in trade-off.