BASIC PRINCIPLE AND METHODOLOGY OF MIMO

1. Overview of MIMO

2.1 Basic Principle

2.2 Important informations on MIMO

License : HSPA+ Downlink 28 mbps per user is implemented in the RNC. MIMO license is

implemented for selected MIMO RRU sites in RNCs.

Transmission Networking Planning: With the MIMO feature, the maximum downlink peak throughput

per subscriber can reach 28 Mbit/s. Therefore the Iub transmission network bandwidth must be at

least 35 Mbit/s.

Subscription Configuration: According to the rate requirement of the operator, the rate should be

expanded to 28 Mbit/s(downlink) to support the HSPA+ MIMO feature.

UE Category : UE category must be 15 to 20 to support 2X2 single carrier MIMO with 16 QAM.

Pilot Channels : As per PSP mode MIMO uses 2 pilot channels (Primary and secondary SPICH) with tow

Power amplifiers(PA). Recommended Output power is 46dbm per site.

Signalling Channel : New HS SCCH 3 type introduced which is divided into Part1 and Part2 .The two

parts carry different control information

Traffic channel : MIMO uses same HSDPA shared traffic channels (HS-DSCH).

Modulation Scheme : QPSK and 16QAM (Same as HSDPA)

2.3 MIMO RRU connection diagram

3.1 RNC Configuration

The RNC-side configuration includes setting up a logical cell, adding an auxiliary pilot channel,

setting the MIMO feature switch, activating the MIMO cell, and querying the cell setup status

3.1.1 Setting Up an MIMO Logical Cell

Run the ADD UCELLQUICKSETUP command to set up a common cell. Then, run the MOD UCELLSETUP

command to set the cell.

If you configure a PSP cell, the TX Diversity Indication parameter can be set to FALSE only. If the value is

set to TRUE, the cell must be an STTD cell. This guide is aimed at the PSP cell. Therefore, the parameter

should be set to FALSE.

3.1.2 Adding an Auxiliary Pilot Channel

On the RNC LMT, run the ADD USCPICH command to add an auxiliary pilot channel.

3.1.3 Turning On the MIMO Feature Switch

For the MIMO switch for the global RNC, run the SET/LST UCORRMALGOSWITCH command to set it and

check the switch status. The below mentioned shown screenshot showsthe MIMO switch for the global

RNC is turned on.

For the MIMO algorithm switch for a cell, run the MOD/LST CELLALGOSWITCH command to set it and

query the switch status. Turn on the L2 enhancement switch when you turn on the MIMO switch. Run

the following commands:

MOD UCELLALGOSWITCH: CellId=40, HspaPlusSwitch=MIMO-1&DL_L2ENHANCED-1;

3.1.4 Activating an MIMO Cell

To set up an MIMO cell, the cell must first support the HSDPA feature. [ADD UCELLHSDPA: CellId=13,

AllocCodeMode=Automatic, CodeAdjForHsdpaSwitch=ON;]

Therefore, you need to first set the HSDPA feature, and then run the ACT UCELLMIMO command to

activate the MIMO cell.

3.1.5 Checking Whether Cell Setup Is Successful

1. Run the DSP UCELL command to check whether SCPICH is successfully set up. As

shown in the information indicates that SCPICH is successfully set up.

2. Run the DSP UCELL command to check whether the MIMO cell is successfully set

up. As shown in the information indicates that the MIMO cell is successfully set up.

3. Check whether the allocated bandwidth is 27.9 Mbit/s.

On the BSC6900 WebLMT, choose Connection Performance Monitoring > DL

Throughput Bandwidth to check the subscriber bandwidth. Error! Reference

source not found. shows that the subscriber bandwidth is 27.9 Mbit/s. it indicates

that the subscriber is an MIMO subscriber.

4. Check the number of MIMO subscribers in the cell.

Choose Cell Performance Monitoring > Cell User Number to check the number of

MIMO subscribers in the cell. The below mentioned figure shown that the number of

MIMO subscribers in the cell is two.

3.1.6 NodeB Configuration

The NodeB-side configuration includes adding a sector, adding a local cell, checking whether the local

cell supports MIMO, and turning on the IIC and APC algorithm switches.

3.1.7 Adding a Sector

On the NodeB LMT, run the ADD SEC MML command to add a sector.

In Diversity Mode, select Common Mode.

Because the LRRU is used, the subrack numbers of the two receiving antennas are the same. (Both are

60 in

In situations with two RRUs, you need to select different subrack numbers but select the same value

R0A(0A) of the antenna channel.

3.1.8 Adding a Local Cell

When configuring a local cell, you need to configure two transmitting antennas. In Two Tx Way, select

TRUE.

When configuring the transmitting diversity, ensure that the maximum transmitting power of the local

cell must be greater than or equal to the maximum transmitting power of the logical cell. The maximum

transmitting power of the local cell is set to 46 dBm, which is greater than the maximum transmitting

power 43 dBm of the logical cell.

In situations with two RRUs, you need to select different subrack numbers but select the same value

R0A(0A) of the antenna channel.