07 Ct82357en01gla1 Mimo for Lte

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    CT82357EN01GLA1 2014 Nokia Solut ions and Networks. All righ ts reserved.

    MIMO for LTE

    LTE Air Interface Course

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    Nokia Solutions and Networks Academy

    Legal notice

    Intellectual Property Rights

    All copyrights and intellectual property rights for Nokia Solutions and Networks trainingdocumentation, product documentation and slide presentation material, all of which are forthwithknown as Nokia Solutions and Networks training material, are the exclusive property of NokiaSolutions and Networks. Nokia Solutions and Networks owns the rights to copying, modification,translation, adaptation or derivatives including any improvements or developments. Nokia Solutions

    and Networks has the sole right to copy, distribute, amend, modify, develop, license, sublicense,sell, transfer and assign the Nokia Solutions and Networks training material. Individuals can use theNokia Solutions and Networks training material for their own personal self-development only, thosesame individuals cannot subsequently pass on that same Intellectual Property to others without theprior written agreement of Nokia Solutions and Networks. The Nokia Solutions and Networkstraining material cannot be used outside of an agreed Nokia Solutions and Networks trainingsession for development of groups without the prior written agreement of Nokia Solutions andNetworks.

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    At the end of this module, you will be able to:

    List the main types of MIMO and their characterist ics Describe the princip les of antenna mapping and precoding

    Explain the transmit d iversity and the spatial multip lexing

    Describe application options of MIMO in relation to radio planning and

    performance issues

    Explain Advanced MIMO techniques

    Module Objectives

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    MIMO for LTE

    Transmission Modes in 3GPP

    Antenna Mapping and Precoding

    Transmission Diversity

    Spatial Multiplexing

    Examples

    Advanced MIMO techniques

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    Multiple-Input Mult iple-Output MIMO Principle

    Tm

    T2

    T1

    Rn

    R2

    R1

    Input

    M x NMIMO

    system

    Output

    MIMO: Multiple-Input Multiple Output

    M transmit antennas, N receive antennas form MxN MIMO system

    Huge data stream (input) distributed toward m spatial distributed

    antennas; m parallel bit streams (Input 1..m)

    Spatial Multiplexing generate parallel virtual data pipes

    Using Multipath effects instead ofmitigating them

    Signal from jthTx antenna

    Sj

    MIMO

    Processor

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    Multiple Antenna Systems

    SIMO MISO MIMO

    Improved

    Transmission

    Reliability

    Greater

    Coverage or

    Range

    Reduced UE

    Power

    Consumption

    Increased

    Transmission

    Throughput

    Multiple Antenna Systems

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    Multiple Antenna Systems, cont.

    LTE Physical Layer services assume multiple port antenna systems are used.Multiple port antenna

    systems are implemented for the following reasons:

    Improved transmission reliability

    Greater coverage or range

    Reduced UE power consumption

    Increased transmission throughput

    Multiple port antenna systems include the following: Single Input Multiple Output (SIMO)

    Multiple Input Single Output (MISO)

    Multiple Input Multiple Output (MIMO)

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    Single Input Multiple Output (SIMO)

    Switched Diversity

    Equal Gain Combining

    Maximum Ratio Combining

    Rx Tx

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    Single Input Multiple Output (SIMO), cont.

    In a SIMO configuration the transmitter (usually the UE) has one transmitter and the receiver (the

    eNodeB) has two physically separated antenna ports. The receiver picks up multiple versions of

    the same signal but separated spatially. SIMO receivers use the following techniques to compute

    the best received signal.

    Switched Diversity

    In Switched Diversity, the input with the best signal is chosen as the best source. The best

    signal may be based on Signal-to-Noise Ratio (SNR) or Bit Error Rate (BER). Switched

    diversity is the most simple and inexpensive SIMO technique.

    Equal Gain Combining

    Equal Gain Combining is a summation of all available received signals.

    Maximum Ratio Combining

    In Maximum Ratio Combining (MRC), each received signal has compensation applied to it

    before being combined to produce a composite single signal. This technique is particularly

    effective where the signal undergoes deep fading. Because fading probably occurs at different

    frequencies on each antenna port, the reliability of the radio link is increased.

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    Multiple Input Single Output (MISO)

    Space-Time Transmit Diversity

    Tx Rx

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    Multiple Input Single Output (MISO), cont.

    A MISO (eNodeB) transmitter has two or more physically separated antenna ports, while the

    MISO (UE) receiver has one antenna. Each Tx port transmits the same information bits. In

    addition to data signals, reference signals are also transmitted via both antenna ports. The

    normal reference signal pattern is sent via the first antenna port and the diversity reference

    signal pattern via the second antenna port.

    In Space-Time Transmit Diversity (STTD) the same data is transmitted simultaneously over

    both Tx ports. On each port, the channel-coded data is processed in blocks of four bits, thenthe bits are time reversed and complex conjugated. The physical separation of the antenna

    ports provides the space diversity, and the time difference derived from the bit-reversing

    process provides the time diversity. These features together make the decoding process in

    the receiver more reliable.

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    Multiple Input Multiple Output (MIMO)

    Improved Transmission Reliability

    Increased Coverage or Range

    Reduced UE Power Consumpt ion

    RxTx

    MIMO systems contain multiple antenna ports at both the transmitter and receiver. The MIMO transmitter

    transmits signals using time, frequency, and space diversity. The MIMO receiver recovers the data

    across multiple receiving antenna ports.

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    MIMO Techniques

    Space-Time Coding (STC) 1 Data Stream

    Spatial Multiplexing 2 Data Streams

    RxTx

    Data Stream 2

    Data Stream 1

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    MIMO Techniques, cont.

    Space-Time Coding (STC) provides diversity gain to combat the effects of unwanted

    Multipath propagation. Similar to STTD, time delayed and coded versions of the same signal

    are sent from the same transmitter antenna. The codes that are used are mainly: trellis and

    block (less complex) codes.

    This improves the SNR for cell edge performance.

    Spatial Multiplexing (SM)

    With Spatial Multiplexing, unique (different) data streams are transmitted over different

    antenna ports.

    Spatial multiplexing can double (2x2 MIMO) or quadruple (4x4 MIMO) capacity and

    throughput. This technique gives higher capacity when RF conditions are favorable and

    users are closer to the eNodeB. The graphic shows spatial multiplexing with a 2x2 MIMO

    configuration. The receiver can identify the transmitting antenna port for each received

    signal

    Si l U MIMO

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    UE

    Single User MIMO

    Improved Performance (STC), or

    Improved Throughput (SM) for Single UE

    eNodeB

    Data Stream 2

    Data Stream 1

    MIMO supports single user MIMO and multi-user MIMO. Single User MIMO improves the

    performance for a UE (via space time coding), or increases the throughput for a UE (using

    spatial multiplexing).

    M lti U MIMO

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