1. LTE-A Relays and Repeaters
May 20, 2008 R
3GPP TSG-RAN WG1 #60
22nd - 26th February, 2010
San Francisco, US
Link Analyses of SU-MIMO Operation for UL of LTE-A with Agreed Simulation Assumptions
Agenda item :
Source : Qualcomm Inc
Document for : Discussion and Decision

2. Introduction Background
In 3GPP RAN1#58bis, the following were concluded for further alignment of simulation parameters in studies of layer shifting + ACK Bundling for UL SU-MIMO:
- Provide correlation statistics of error events of two TBs
The throughput results should be accompanied by the assumptions on the
respective BLER targets of 2 CWs
Composite UL-CQI delay/periodicity impact: Measured in subframe n, apply
in n+10
Gaussian noise (in lognormal) is added to the SINR upon which the link
adaptation is based
This noise is to model the uncertainty of UE power headroom, flashlight
effect, channel estimation error
Exact method to be further discussed, e.g. 2-3dB (lognormal) variation
for flashlight effect
Link adaptation should assume the highest MCS that still meets 10% BLER
target (outer loop)
- 25% BLER results can also be considered

3. Introduction Contents of this contribution
In this document, with the agreed simulation parameters, we
compared the two remaining options for UL SU-MIMO
operation:
- Option 1: no Layer Shifting & no ACK Bundling (LP0+AB0)
- Option 2: Layer Shifting & ACK Bundling (LP1+AB1)
Meanwhile, the requested statistics of error events of the two
codewords are provided.

4. Simulation Parameters
Carrier frequency
2.0GHz
System bandwidth
5MHz
Data transmission BW
4 RBs (48 subcarriers)
Slot format
Normal CP (7 symbols per slot)
Channel model (PDP)
Typical Urban, 6 paths
Fading speed
3, 30, 60, 120km/h
Antenna configuration
2x2
Tx Antenna correlation
0.0
Rx Antenna correlation
Channel coding
Turbo code
Modulation
QPSK, 16QAM, 64QAM
Receiver
MMSE-SIC
Channel estimation
Perfect
AMC target BLER
10% at 1st subpacket for both CWs
Link measurement/prediction delay
10ms
Precoding codebook
2x2 Identity matrix
Layer blanking during re-txmn for 2 Ack/Nacks No
Interference Variation Modeling for
Link Prediction (dB)
Gaussian with 2.5dB deviation
AGI
0, 6dB

5. Interference Variation Modeling
Parameter
Configuration
Simulation Scenario
D1 (500m ISD)
19 Cell-Sites wrap-around layout
Traffic Model
Full Buffer
#UEs/Cell 10
Max UE Tx Power
23dBm
Configured SRS Period
Once every 2ms
Channel Estimation Loss
Modeled
Channel Model
Typical Urban
Receiver
LMMSE
Overload Indicator (OI)
Sent Period
10ms
X2 Delay Modeling
Exponential with 20ms mean
min: 10ms, max: 100ms
Power Control Algorithm
Adaptive Power Control
IoT Target
7.0dB
Antenna Config
1x2
Scheduling Algorithm
Proportional fair with
sub-band scheduling
(1 subband = 4RB)
Adaptive Power Control:
Every 10ms, each cell sends the OI via X2 interface, the serving cell
receives the relevant OIs from neighbors and determines the PSD
adjustment for each scheduled UE. A UE will change its PSD as it
receives its scheduling grant:
IF Overloaded
NextScheduledPSD = PreviousScheduledPSD – Delta_Dw;
ELSE
NextScheduledPSD = PreviousScheduledPSD + Delta_Up;
where Deleta_Dw and Delta_Up are chosen from {0.4, 0.8}dB adaptively according to the received SINR.

6. Simulation Results: AGI=0dB, 3km/h
Prob(CW2 Terminates at 1st Txmn | CW1 Terminates at 1st Txmn)
Achieved BLER at 1st Txmn for each Codeword

7. Simulation Results: AGI=0dB, 30km/h

8. Simulation Results: AGI=0dB, 60km/h

9. Simulation Results: AGI=0dB, 120km/h

10. Simulation Results: AGI=6dB, 3km/h

11. Simulation Results: AGI=6dB, 30km/h

12. Simulation Results: AGI=6dB, 60km/h

13. Simulation Results: AGI=6dB, 120km/h

14. Conclusion
From previous simulation results, we can have the following observations:
layer shifting with 1 ACK option achieves
similar performance as no layer shifting with 2 ACKs at low mobility
better performance than no layer shifting with 2 ACKs at medium to high mobility
As a result we recommend the following:
Layer shifting with a single ACK as a single LTE-A UL MIMO operation mode
References:
[1]. R , “Link Analyses of SU-MIMO for UL of LTE-A,” Qualcomm Europe.
[2]. R , “Further Link Analyses of SU-MIMO Operation for UL of LTE-A,” Qualcomm
Europe.