1 © Nokia Siemens Networks 2011For internal use

NWS LTA RA E2E SA Network Engineering / Hubert Grzesiński

Technical DetailsRAN1642 MIMO 28MbpsRAN1912 MIMO 42Mbps

2 © Nokia Siemens Networks 2011For internal use

NWS Network Engineering / Hubert Grzesiński

MIMO Transmission Concept (1/4)

S1: TBS A

S2: TBS A

TRANSMIT AND RECEIVE DIVERSITY

S1: TBS A

S2: TBS B

SPATIAL MULTIPLEXING

• MIMO refers to multi antenna technology system using multiple input signals and multiple output signals from a single channel

• Requires two different antennas on UE side and NodeB side• MIMO introduces spatial diversity and spatial multiplexing

– Spatial diversity – signal copies are sent by two antennas and received at more than one antenna. It improves signal quality

– Spatial Multiplexing – more than one stream is sent over one frequency simultaneously• Requires second CPICH for estimation of the air interface channel• Two modes of MIMO transmission possible: Single Stream and Dual Stream

3 © Nokia Siemens Networks 2011For internal use

NWS Network Engineering / Hubert Grzesiński

MIMO Transmission Concept (2/4)

HS-DSCHTBS

1 TBS 2

Rank 2, TF1, TF2, PCI HS-SCCH

2xCQI A, (N)ACK(s), Rank 2, PCIHS-DPCCH

HS-DSCHTBS

1 TBS 1

Rank 1, TF1, PCI HS-SCCH

CQI B, (N)ACK(s), Rank 1, PCIHS-DPCCH

SINGLE STREAM

DUAL STREAM

Same information through two different Transport

Block Sets : TBS1 & TBS2 (TBS2 = TBS1).

Max theoretical throughput = 14.4 Mbps (16QAM) or

21Mbps (64QAM)

Two different Transport Block Sets : TBS1 & TBS2

(TBS1 ≠ TBS2).

Max theoretical throughput = 28.8 Mbps (16QAM) or

42Mbps (64QAM)

In Single Stream Mode CQI type B are being reported (value range 0– 30)

In Dual Stream Mode CQI type A are being reported (value range 0– 14)

• BTS decides whether single or dual stream mode should be used. • Decision depends on, among other factors, information which is sent by UE (PCI, CQI,

ACK/NACK)

4 © Nokia Siemens Networks 2011For internal use

NWS Network Engineering / Hubert Grzesiński

MIMO Transmission Concept (3/4)MIMO Weights

• The spread and scrambled signals are fed to TX branches and weighted with precoding weights w1, w2, w3, w4

• Primary precoding vector (w1, w2) is used for transmitting the primary transport block

• Secondary precoding vector (w3, w4) is used for transmitting the secondary transport block

• w1 is fixed and defined on NodeB• w2 is chosen by NodeB on basis of feedback

information from UE via PCI (Precoding Control Information) in order to SINR optimization

• w3 and w4 have to be mutually orthogonal to primary precoding vector and are defined base on w1 and w2 weights

Due to it the secondary precoding vector is not optimal from SINR optimization point of view – Second stream conditions are worse than first stream

Conditions on stream 1 are always better

Primary transport block

Spreading/ scremabling

∑

P-CPICH

∑S-CPICH

w1

w2

Other CCHs1

s2

V-ANT1

Secondary transport block

w3

w4

V-ANT2

21,

21,

21,

21

2jjjjw

21

13 ww 24 ww

5 © Nokia Siemens Networks 2011For internal use

NWS Network Engineering / Hubert Grzesiński

MIMO Transmission Concept (4/4)PCI and CQI Information

• In MIMO case two different types of CQIs are used:

• CQI Type A – are used for Dual Stream transmission

• CQI Type B – are used for Single Stream transmission

• PCI (Precoding Control Indication) contains information about preferred precoding weight w2

• Preferred precoding weight value is chosen by UE based on Primary and Secondary CPICH measurements and send to NodeB

CQI TBS Modulation0 4581 QPSK1 4581 QPSK2 5101 QPSK

...

10 23370 16QAM11 25558 16QAM12 26969 16QAM13 27456 16QAM14 27952 16QAM

CQI TBS Modulation0 4581 QPSK1 4581 QPSK2 5101 QPSK

...

10 27960 64QAM11 32264 64QAM12 36568 64QAM13 39984 64QAM14 42192 64QAM

CQI A – MIMO 28MBPS*

CQI A – MIMO 42MBPS*

Higher Modulation Order

*All CQI tables are available in 3GPP TS 25.214

PCI Values

0

1

2

3

prefw2

21 j

21 j

21 j

21 j