MIMO

MIMO : MIMO MIMO

Slide 2 : Presented by... Sk.Gulshan Masud Hossain Riddhi Chakraborty Shimul Ghosh Arko Ghosh Tanay Saha Dalal Sarthak Saptarshi Bandopadhyay Under the able Guidance of …….. Prof. Sudip Dogra (HOD,ECE)

First Generation (1G) Systems : First Generation (1G) Systems AMPS, the first generation cellular systems using analog voice transmission came into operation in 1983 and were referred to as an analog technology. This is because the RF carrier is modulated and transmitted using frequency modulation (FM), a simple analog modulation technique, with Frequency Division Multiple Access (FDMA) as the channel multiple access method. However, the control of the connection set up, the change of the base stations during a connection, (so-called hand-over or handoff) caused by the mobile station mobility, as well as other control procedures such as mobile station control, are implemented by transmission of digital signals.

Drawbacks of 1G : Drawbacks of 1G The first generation systems suffer from: Poor voice quality Poor battery life Large phone size No security, frequent call drops Limited capacity and poor handoff reliability between cells Much more modern systems technologically better than AMPS,are now available

2G SYSTEMS : 2G SYSTEMS The development of the digital technology, on one hand, and frequent cases when analog systems reached their full capacity, especially in big cities, on the other hand, led to the development of the second-generation (2G) systems. The main aim in the design of the 2G systems was the maximization of the system capacity measured as the number of users per spectrum per unit area. 2G networks are digital, both systems use digital signaling to connect the radio towers (which listen to the handsets) to the rest of the telephone system. Three primary benefits of 2G networks over their predecessors were that phone conversations were digitally encrypted, more efficient on the spectrum allowing for far greater mobile phone penetration levels; and data services for mobile, starting with SMS.

CAPACITY OF 2G SYSTEMS : CAPACITY OF 2G SYSTEMS Using digital signals system capacity in two key ways: Digital voice data can be compressed and multiplexed much more effectively than analog voice encodings through the use of various codecs, allowing more calls to be packed into the same amount of radio bandwidth. The digital systems were designed to emit less radio power from the handsets. The cells are smaller, so more cells could be placed in the same amount of space.

DRAWBACKS OF 2G : DRAWBACKS OF 2G There are drawbacks to the current GSM: The GSM is a circuit switched, connection oriented technology, where the end systems are dedicated for the entire call session. This causes inefficiency in usage of bandwidth and resources. The GSM-enabled systems do not support high data rates. They are unable to handle complex data such as video. These devices have small hardware configurations with less powerful CPUs, memory and display units, and support simple functionality. Only basic messaging services such as SMS can be supported. The GSM networks are not compatible with the current TCP/IP and other common networks because of differences in network hardware, software and protocols

Evolution of Wireless Sys. (2.5G) : Evolution of Wireless Sys. (2.5G) 2G telephony is highly successful Enhancement to 2G on data service GSM: HSCSD and GPRS IS-95: IS-95b IS-136: D-AMPS+ and CDPD The improved data rate is still too low to support multimedia traffic ITU initiated 3G standardization effort in 1992, and the outcome is IMT-2000.

Goals of 3G Systems : More services Web browsing VoD Video phone call Mobile computation Improved quality Higher rates: 2.048 Mbps for low speed users, 384 Kbps for modest speed users and 144 Kbps for high speed users More reliable and larger capacity Compatible with 2G systems More flexible Support both circuit-switching and packet-switching Work in hierarchical mode with pico-/micro-/macro-cells Support asymmetric services … Goals of 3G Systems

Evolution of Wireless Sys. (4G) : Evolution of Wireless Sys. (4G) Problems of 3G systems Immature 3G license auction increases the financial burden What are the killer applications of 3G? No unified standard (political factors dominate) 4G systems Research initiated, but still not well-defined Data-oriented, seamless integrated with wireline Indoor data rate up to 100 Mbps, outdoor data rate up to 20Mbps.

Slide 13 : Paradigm From 1G to Beyond 3G

Existing Problems : Existing Problems Unable to support high quality video streaming due to the limited data rates achievable over wireless links. Scarcity of spectrum Limited transmit powerFluctuations in wireless links due to fading.

WHY IS MIMO? : WHY IS MIMO?

Solutions : Solutions MIMO technology has attracted attention in wireless communications, since 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 .

What is MIMO? : What is MIMO?

Slide 18 : MIMO (multiple input, multiple output) is an antenna technology for wireless communications in which multiple antennas are used at both for transmission and reception. The antennas at each end of the communications circuit are combined to minimize errors and optimize data speed. It increases the capacity of the wireless channel. Multi-user MIMO for Broadband Wireless Communication Systems

Slide 19 : Forms of MIMO

MIMO Makes Wireless a Viable Home Connectivity Option : MIMO Makes Wireless a Viable Home Connectivity Option The costs and hassles of running cables through the home have been removed Consumers now have an easy and convenient way to connect and get reliable coverage With MIMO performance the wireless Digital Home can become a reality Businesses The Economic Benefit Wireless MIMO Applications The Consumer Experience

Slide 21 : How MIMO Works Multiple data streams transmitted in a single channel at the same time Multiple radios collect multipath signals Delivers simultaneous speed, coverage, and reliability improvements

MIMO channel model : MIMO channel model

MIMO channel model : MIMO channel model In MIMO systems, a transmitter sends multiple streams by multiple transmit antennas. The transmit streams go through a matrix channel which consists of multiple paths between multiple transmit antennas at the transmitter and multiple receive antennas at the receiver. Then, the receiver gets the received signal vectors by the multiple receive antennas and decodes the received signal vectors into the original information. Here is a MIMO system model: y = Hx + n y and x are the receive and transmit vectors, respectively. In addition, and are the channel matrix and the noise vector, respectively.

Functions of MIMO : Functions of MIMO

Precoding : Precoding Precoding is multi-layer beamforming in a narrow sense or all spatial processing at the transmitter in a wide-sense. In (single-layer) beamforming, 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 beamforming are to increase the signal gain from constructive combining and to reduce the multipath fading effect.

Spatial Multiplexing : Spatial Multiplexing 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, creating parallel channels for free. Spatial multiplexing is a very powerful technique for increasing channel capacity at higher Signal to Noise Ratio (SNR).

Diversity Coding : Diversity Coding 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 using certain principles of full or near orthogonal coding. Diversity exploits the independent fading in the multiple antenna links to enhance signal diversity. Because there is no channel knowledge, there is no beamforming or array gain from diversity coding.

Antenna Design and Analysis for MIMO Communication Systems : Antenna Design and Analysis for MIMO Communication Systems

Introduction to MIMO Antenna Design : Introduction to MIMO Antenna Design Multiple-input multiple-output (MIMO) wireless technology uses multiple antennas at the transmitter and receiver to produce significant capacity gains over single-input single-output (SISO) systems using the same bandwidth and transmit power. It has been shown that the capacity of a MIMO system increases linearly with the number of antennas in the presence of a scattering-rich environment. This will ensure that the signals at the antennas in the array are sufficiently uncorrelated with each other. This is where antenna design comes in for MIMO systems

Primary aim of MIMO antenna design : Primary aim of MIMO antenna design To reduce correlation between received signals by exploiting various forms of diversity that arise due to the presence of multiple antennas, like : Space diversity (spacing antennas far apart), Pattern diversity (using antennas with different or orthogonal radiation patterns), Polarization diversity (using antennas with different polarizations) etc.

MIMO Relay Channels : MIMO Relay Channels

Why study MIMO Relay Channels? : Why study MIMO Relay Channels? Relay channels will play a central role in next-generation wireless systems. If a source wants to send a message to a distant sink in a relatively dense network, it can forward the message via several intermediate nodes. This would improve overall throughput and coverage.

Slide 35 : We can consider SISO relay channels, where each terminal employs a single antenna. Under this setup, though, there are channel conditions where the relay may not be able to assist the source in its transmission. For example, the minimum of the source-relay and relay-sink channel gains may be less than the source-sink channel gain. We can avoid this issue by considering MIMO relay channels, where each terminal employs multiple antennas. Under this setup, we can exploit the multiple antennas at the source and the relay to perform more sophisticated encoding and decoding schemes, which will lead to improved performance.

Lab VIEW MIMO Toolkit : Lab VIEW MIMO Toolkit

Slide 37 : Modulation: Two types of modulation scheme are offered namely PSK (Phase Shift Keying) and QAM (Quadrature Amplitude Modulation). Modulation & Encoder :This set of vis is encodes the modulated signal, some of the vis performs modulation along with encoding. Vis include in this category are Alamouti encoder, Trellis encoder, Linear Dispersive encoder and Spatial multiplexer. Channel :These vis simulate the wireless channel, the two options available are Rayleigh fading channel (with or without tap) and Ricean channel. Decoder & demodulator :After going through the channel, the vis are decoded and demodulated and a decision is made on the symbol sent. The vis in this category are Alamouti decoder, Trellis decoder, Linear Dispersive decoder, Maximum likelihood receiver, Linear receiver and Successive Interference Cancellation receiver (V-BLAST).

Slide 38 : Orthogonal Frequency Division Multiplexing (OFDM) : There are vis available that allow OFDM to be simulated along with MIMO systems. OFDM variant are available for Maximum likelihood, Successive Interference Cancellation and Linear receiver. Extra vis : Vis that convert bits to symbols and vice versa are available. Also present are vis that read/write graphs to and from files, along with them is a vi that reads complex matrices from text files. Space-Time Equalizer and Viterbi decoder : This palette contains vis required for simulating a multi-user MIMO channel and equalizing the received symbols to suppress co channel, co antenna and intersymbol interference. This palette is self-contained and doesn't require the other vis in the toolkit. This includes a Console vi which generates the structured input and channel matrices required for the other vis in the palette, a Space-Time Equalizer vi, a Space -Time Equalizer vi with channel shortening and a single-channel Viterbi decoder for intersymbol interference suppression.

Space Time block Code : Space Time block Code Space time block coding is a simple transmit diversity technique in MIMO systems. ENCODER FOR STBC Information source Modulator Space time block Encoder Tx1 s1 Tx2 s2

Space Time Block Code systems : Space Time Block Code systems Alamouti’s space time code theory paved the path for space time block code. Let Mt represent the number of transmitting antennas the time periods of one block of coded symbols & the signal constellations consists of 2m points. Each encoding maps a block of km information bits to select k modulated signals. These are encoded in space time block encoder to generate Mt parallel signal sequences of length P. We get transmission matrix S(Mt P).Transmitted through Mt in p time periods. There fore rate is R=K/p and efficiency is km/p bits/s/Hz.

Slide 42 : ADVANTAGES : Full Transmit Diversity. Allows the receiver to decouple the signals transmitted from different antennas. Simple decoding techniques are used. Simple to design based on orthogonal sequences. DISADVANTAGES: Do not provide Coding gain. Losses capacity with two or more antennas.

Space Time -Trellis coding : Space Time -Trellis coding It is a type of coding technique by which we ca n implement error control,modulation and have transmit and receive diversity. Block Diagram of space time-trellis code Information source Modulator Space time block Encoder Tx1 s1 Tx2 s2

Slide 44 : ADVANTAGES : Has coding gain. Preserves capacity irrespective of the number of antennas. DISADVANTAGES: Difficult to design.

Slide 45 : Imagine A World Where… You never see or pull a cable Multimedia applications of the future are enabled wirelessly All network connections are as reliable as your dial-tone All content is at your finger-tips

Applications of MIMO : Applications of MIMO Spatial multiplexing techniques makes the receivers very complex, and therefore it is typically combined with Orthogonal frequency-division multiplexing (OFDM) where the problems created by multi-path channel are handled efficiently. The IEEE 802.16e standard incorporates MIMO-OFDMA. The IEEE 802.11n standard, which is expected to be finalized soon, recommends MIMO-OFDM. MIMO is also planned to be used in Mobile radio telephone standards such as recent 3GPP and 3GPP2 standards. 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, i.e., multi-user MIMO (MU-MIMO)

Slide 47 : MIMO Enables the Digital Home MIMO delivers whole home coverage with the speed and reliability to stream multimedia applications MIMO can reliably connect cabled video devices, computer networking devices, broadband connections, phone lines, music, storage devices, etc. MIMO is interoperable and can leverage the installed based of 802.11 wireless that is already deployed: computers, PDAs, handheld gaming devices, cameras, VoIP Phones, etc.

Slide 48 : MIMO Wireless Enables New Applications and Business Models VoIP and Other New Easy to Use Applications Guaranteed Whole Home Coverage Enables New Cable-Free CE Device Markets Enables Enhanced Cable MSO Business Models (reduced truck rolls) Enables RBOCs & On-Line Movie Co’s To Offer Streaming Video Services Enables New Mobile Hotspot Video and Multimedia Services MIMO Radio Hassle-Free PC Networking Self Install Plasma, Cable & DSL Picture & Video Sharing Internet Based Video Streaming Enabling Technology New Applications New Markets

Thank You! : Thank You!