F01 beam forming_srs

Soc Classification level
1 © Nokia Siemens Networks
Beamforming + SRS optimization
LTE OPT Training
Last Updated: April 19th, 2012
Version 1.0

Outline
• Overview
• Sector beam for common channels
• RL15 vs RL25 beamforming for PDSCH
• Sounding Reference Signal
• Performance results
• Parameters
This is mostly adapted from NetEng presentations,
see:
https://sharenet-ims.inside.nokiasiemensnetworks.com/Open/408525471

3 © Nokia Siemens Networks /
3GPP R9 TM mode / NSN implementation
“Transmission mode”
as 3GPP TS36.213
“dlMimoMode” as NSN
0 1 2 3 4 5(TDD only) 6TDD only)
Single
Stream
Downlink
Single
Stream
Downlink
Transmit
Diversity
Dual
Stream
Downlink
MIMO
Dynamic
Open
Loop
MIMO
Dynamic
Closed
Loop
MIMO
Single stream
beamforming
dual stream
beamforming
TM1: Single-antenna port; port 0
TM2: Transmit Diversity
TM3: Open Loop spatial Multiplexing
TM4: Closed Loop Spatial
Multiplexing
TM5: Multi-user MIMO
TM6: Closed Loop Rank=1 precoding
TM7: Single-antenna port; port 5
TM8: dual Dual layer transmission;
port 7 and 8 (see 3GPP 36.213
subclause 7.1.5A) or single-antenna
port; port 7 or 8 (see 3GPP 36.213
subclause 7.1.1)

BF General
System module
…
RF module
Optical RP3-01
DC power
Antenna RF (one BF group)
BF Calibration
Antenna RF (one BF group)

•UE beam
Traffic channels over UE beam
Downlink coverage enhancement
Downlink interference reduction
User tracking
•Sector beam
Broadcast / control channels over sector beam
BF General

BF General
---- BF gain
4W
0.04W or 0.16W?1W
1W
1W
0.04W
1W
Should be 0.16w
when BF works

Example x-pol 2x4 element BF antenna

BF General
---- BF gain, RL15 BF with TM3/TM7 switching
IMT-A UMaLOS CFI=3 CCE=8
0
5000
10000
15000
20000
25000
30000
35000
40000
30 26 22 18 14 10 6 2
SNR based on input measurement
averageDLTRPTin30S
TM2_3
Tm7_3
Lab test result for TM2/TM7 under LOS 3km/h

9 © Nokia Siemens Networks Presentation / Author / Date
Adaptive Switch Between TM3 and TM7, early DT

BF General
---- BF pattern examples
-150 -100 -50 0 50 100 150
-30
-25
-20
-15
-10
-5
0
5
Gain[dB]
Degree
BF,phi=-30
BF,phi=0
BF,phi=30
Unit Beam
6dB array gain
Beam width: 25’
Beam width: 90’1
2
3
4
30
210
60
240
90
270
120
300
150
330
180 0
BF,phi=-30
BF,phi=0
BF,phi=30
Unit Beam

Implementation for TD-LTE
---- Beamforming procedures
Step1: DL common RS for cell access
Step2: UL sounding RS + CQI
feedback
Step3: Beam generation at eNB
Step4: DL data transmission w/ DRS
Cell coverage w/ CRS
UE-specific spatial beam
w/ DRS

Beamforming Limitations
• Limitations of Applying Beamforming (DL)
– How reliable is channel reciprocity in TDD ? (*)
– Sounding period/bandwidth has large impact of BF performance (*)
– DL BF antenna need extra Calibration
 Calibration is a complex, expensive and nonstandard function which needs hardware
support in the RF parts of the base station
– Beamforming cannot be applied in control channel, no gain about control
channel coverage
- Latency and inaccuracy of UL measurements, limits to users with low to
medium velocity (50km/h)
- DL Beamforming produces interference flashlight effect which makes inter-cell
interference very unstable
* For EBB type of “slow” Beamforming

Legacy Terminal Co-Existence
• LTE FDD Release 8 UEs do not support beamforming. If beamforming is
introduced to FDD network later, Release 8 UEs can co-exist on the
same carrier but Release 8 will not get beamforming gain.
• Release 8 UEs support max 4x4 MIMO. If 8x8 MIMO is introduced with
Release 10, then Release 8 UEs can co-exist on the same carrier but
Release 8 can utilize maximum 4x4 MIMO.

Outline
• Overview
• Parameters

PA
Total: 40W
5W 5W 5W 5W
XW1
X
X
X
W2
W3
W4
SFBCPDSCH
5W 5W 5W 5W
X W1
X
X
X
W2
W3
W4
PDSCH
• Sector beam: virtualization via weight factor.
• 8 PA (Power Amplifier), each with 5W. Total:
40W
• Two beams, each beam is formed from co-
polarized 4 antennas. SFBC may be applied for
two groups of antenna.
• Single antenna pattern: 90 degree.
• Static weight factor [3]: W= [0.35, 1, 1, -0.6]
• Sector 3dB beam width: 65’
Implementation for TDLTE
---- sector beam via weight factor
• Reference: 2 un-correlated antennas
• 2 PA, each with 20W. Total: 40W
• Two beams, each beam is formed from
independent antenna.
• Single antenna pattern: 70 degree.
• Sector 3dB beam width: 70’
PA
Total: 40W
20W 20W
PDSCH
Reference:

---- sector beam via weighted factor
-150 -100 -50 0 50 100 150
-30
-25
-20
-15
-10
-5
0
5
Gain[dB]
Degree
sectorBeam
Ref:70-degree
Beam width:
65'
Loss on the
antenna gain

Sector beam configuration in BTS
## Excerpt from RL15 BTS swconfig file
## Fix the Antenna weight vector according to the feedback from COMBA
0x00120132 = 0x35050000
0x00120133 = 0xAE6E0000
0x00120134 = 0xB26D1935
0x00120135 = 0xEFB00000
0x00120136 = 0x35050000
0x00120137 = 0xAE6E0000
0x00120138 = 0xB26D1935
0x00120139 = 0xEFB00000
Angles Broadcast Gain(dBi)
Service
Gain(dBi)
Minus(d
B)
0° 14.7 22 7.3
30° 13.8 20 6.2
60° 5.7 14.7 9
• In their datasheets, antenna manufacturers provide antenna pattern with certain fixed BF
weights
• Example of Comba pattern: Comba “Broadcast pattern” corresponds to NSN “sector beam”
To use the antenna manufacturer
broadcast pattern as sector beam,
static antenna weights must be
provided in the BTS swconfig file
(read at BTS boot)

Outline
• Overview
• Parameters

• LTE493 versus LTE541
– new in RL15: LTE493 single stream BF (SS-BF) TM7 (3GPP release 8)
– new in RL25: LTE541 dual stream BF (DS-BF) TM8 (3GPP release 9)
• same BTS antenna configuration (4 x-polarized antennas)
• LTE493 (SS-BF)
– all 8 antennas regarded as single logical antenna => single stream-BF
– channel vector averaged over time => long term BF (LTBF)
• LTE541 (DS-BF)
– 2 logical antennas (port 7 and 8) => dual stream-BF
– => user throughput doubled under ideal conditions
– both port 7 and 8 comprise all 8 antennas (distinction via CDM)
– also single stream supported (all 8 antennas used)
– instantaneous channel vector => short term BF (STBF)
• LTE493 and LTE541
– UE specific channel sounding via SRS used for UL channel estimation
– => consecutive generation of DL weights for PDSCH and dedicated reference signal (DRS)
• RL25: per cell either LTE493 or LTE541 activated => also LTE493 supported
RL15 vs RL25 BF

---- port0/1/5 (port 5 is for TM7 single-stream BF)
SRS
Weighted
PDSCH & DRS
DL channel coefficient
acquisition based on
UL SRS
Weight factor
calculations base on dl
channel coefficient
Step 1
Step 2,3
UE beam
Single Antenna
Port + Sector Beam
TxDiv + Sector
Beam Beamforming
PBCH
PDCCH
PHICHControl
Channels PCFICH
Data Channels PDSCH * Note 1 * Note 2
PSS
Via Antenna Port 0
*
Sych Signals SSS
Via Antenna Port 0
*
Cell Specific
RS
Via Antenna Port
0,1 *
Ref. Signal UE Specific RS
R5
R5
R5
R5
R5
R5
R5
R5
R5
R5
R5
R5

weighting
vector
long term weights
(LTBF)
short term weights (STBF)
(MIMO: pre-coding matrix PM)
LTE541
structure
2
3
4
7
8
w2
w3
w4
w5
w6
w7
w8
1w1 5
u1u2u3u4
w1
w2
CW1
Long term weight
Short term weight
6
2/
single stream case
(1 code word)
dual stream case (2
code words)
2
3
4
6
7
8
w2
w3
w4
w5
w6
w7
w8
1w1 5
u1u2u3u4
w11
w12
w21
w22
CW1
CW2
Long term weight
Short term weight
2/
short term BF +
long term BF =
hybrid BF
In RL15
w1 =w2=1
(fixed)

2
3
4
6
7
8
w2
w3
w4
w5
w6
w7
w8
1w1 5
u1u2u3u4
w11
w12
w21
w22
CW1
CW2
Long term weight
Short term weight
2/
LTE541, DS-BF
feature description (2)
short term weights
• default: STBF based on
instantaneous channel
vector H (estimated from
SRS, “Hybrid BF”)
• fallback 1: UE’s PMI
feedback (“PMI + LTBF”)
• fallback 2: random matrix
(“Unitary BF”)
• H and reported PMI
regarded as invalid if
older than a certain #TTIs
u: long term weights, computed via LTBF
• SRS based estimation of channel response H
• H averaged over PRBs and time
• LTE493: LTBF over 8 antennas
• LTE541:
– LTBF over 4 antennas per polarization
– => 1 H vector per polarization
– => both H vectors averaged
– same u vector applied to both polarizations
weighting vector (w,
Kronecker product
of long and short
term weights)

LTE541, DS-BF, FTM-858
dynamic rank switching inside TM8
• rank switching between SS-TM8 and DS-TM8 (no mode switching!)
• definitions
– “currentMode”: eNB internal status for current BF mode (SS-BF and DS-BF)
– mimoCQI: filtered CQI value at time t
– mimoRANK:filtered rank value at time t
• upgrade rule: switching from SS-BF to DS-BF if
– mimoCQI > bfCqiThUp AND mimoRANK > bfRankThUp
• downgrade rule: switching from DS-BF to SS-BF if
– mimoCQI ≤ bfCqiThDown OR mimoRANK ≤ bfRankThDown
• BF mode not changed if none of the above rule applies
• setting of CQI and rank thresholds may deviate from the respective MIMO
parameters

LTE541, DS-BF
fall back and dynamic rank switching
DS-BF
(TM8 only)
SS-BF
(TM7 or TM8)
Tx Div
(TM7 or TM8)
dynamic rank switching (CQI, rank)
(TM8 only, both directions)
TxDiv fall back (CQI, rank)
(TM8 only, both directions)
TxDiv fall back (CQI, rank)
(both directions)
formally not TM2 (“TM2 with 8 antennas” (sector beam))

Outline
• Overview
• Parameters

SRS Hopping pattern examples I (UpPTS, 4 PRBs)
Cell bandwidth Cell spec. SRS bandwidth SRS hopping bandwidth UE SRS bandwidth UE SRS periodicity
20 MHz => 100 PRBs CSRS = 0 => 96 | 48 | 24 | 4 bhop = 0 => hop via 96 PRBs BSRS = 3 => 4 PRBs TSRS = 10 => 10 ms
No sounding by
UE in every 2nd
half frame as
TSRS=10ms
Unsounded
band segment
(valid for this
UE at a given
hopping start
point!)
Sounding cycle
finished &
resumed after
240 ms
Sounding in TD-LTE - Feature Presentation

SRS Hopping pattern examples IV (UpPTS, 24 PRBs)
Cell
bandwidth
20 MHz
=> 100 PRBs
Cell spec.
SRS
bandwidth
CSRS = 0
=> 96 | 48 | 24 | 4
SRS
hopping
bandwidth
bhop = 0
=> hop via 96
PRBs
UE SRS
bandwidth
BSRS = 2
=> 24 PRBs
UE SRS
periodicity
TSRS = 10
=> 10 ms
Sounding cycle
finished &
resumed after
40 ms
Cell
bandwidth
20 MHz
=> 100 PRBs
Cell spec.
SRS
bandwidth
CSRS = 0
=> 96 | 48 | 24 | 4
SRS
hopping
bandwidth
bhop = 0
=> hop via 96
PRBs
UE SRS
bandwidth
BSRS = 2
=> 24 PRBs
UE SRS
periodicity
TSRS = 5
=> 5 ms
Sounding cycle
finished &
resumed after
20 ms
unsounded
unsounded
unsounded

SRS Hopping pattern examples V (UpPTS, 48 PRBs)
Cell
bandwidth
20 MHz
=> 100 PRBs
Cell spec.
SRS
bandwidth
CSRS = 0
=> 96 | 48 | 24 | 4
SRS
hopping
bandwidth
bhop = 0
=> hop via 96
PRBs
UE SRS
bandwidth
BSRS = 1
=> 48 PRBs
UE SRS
periodicity
TSRS = 5
=> 5 ms
Sounding cycle finished
& resumed after 10 ms
unsounded
unsounded
UE1 UE2
unsounded
Two UEs with different frequency
domain starting positions
Two UEs with different frequency
domain starting positions

SRS Hopping pattern examples VI (UpPTS, 96 PRBs)
Cell
bandwidth
20 MHz
=> 100 PRBs
Cell spec.
SRS
bandwidth
CSRS = 0
=> 96 | 48 | 24 | 4
SRS
hopping
bandwidth
bhop = 0
=> hop via 96
PRBs
UE SRS
bandwidth
BSRS = 0
=> 96 PRBs
UE SRS
periodicity
TSRS = 10
=> 10 ms
Cell
bandwidth
20 MHz
=> 100 PRBs
Cell spec.
SRS
bandwidth
CSRS = 0
=> 96 | 48 | 24 | 4
SRS
hopping
bandwidth
bhop = 0
=> hop via 96
PRBs
UE SRS
bandwidth
BSRS = 0
=> 96 PRBs
UE SRS
periodicity
TSRS = 5
=> 5 ms
unsounded

Outline
• Overview
• Parameters

LTE493, SS-BF, summary of simulations
• BF impact on specific UEs
• Rx power (S): always higher (ideally up to 6 dB)
• interference (I): depends on position of victim and interfering UE
• SINR (= S-I-N): at least as good as without BF
• overall BF impact
• Rx power (S): ideally up to 6 dB higher
• interference (I): same as without BF
- same total Tx power => same interference power on air
- strong fluctuations (flash-light effect)
• SINR (= S-I-N): ideally up to 6 dB higher
 improved SINR should apply to both good and bad (cell edge) users, but
 good users already use high MCS (e. g. may switch from MCS27 to MCS28)
 cell edge users may use much higher MCSs
 => expectation: BF improves cell edge TP more than cell average TP

• LTE541 comprises both single and dual stream beamforming
• comparison
– feature SS with LTE493 SS with LTE541
– RL RL15 RL25
– BF-method LTBF Hybrid
– FD: frequency domain averaging frequency selectivity
– TD: time domain averaging inst. channel info
– LL reference about 2~3 dB better
• LTBF
– better LL performance in channel models with low AS (dominant eigenvector!)
– AS at BTS: SMaNLoS: 5° UMaNLoS1: 8° UMaNLoS2: 15°
– => best LL performance for SMaNLoS (Suburban Macro NLoS)
LTE541, DS-BF
LL results

physical logical long term weights BF algorithm
2x2
MIMO
2
(1 + 1)
2
dynamic
(1 or 2)
- - dynamic CL MIMO 1.00 1.00 RL15 TM4
LTE493
8
(4 + 4)
1 1
LTBF over
8 antennas of
both polarizations
(8x8 covariance
matrix)
LTBF
-
(single logical antenna)
1.03 1.43 RL15 TM7
Hybrid BF
(default)
"continous PM"
calculated via STBF
(based on instantaneous
channel estimation)
1.26 1.43
PMI + LTBF
(fallback for
invalid H vectors but
valid PMI feedback)
PM based on PMI
reports and code book
(3GPP 6.3.4.2.3 of
36.211)
- -
Unitary LTBF
(fallback for
invalid H vectors and
invalid PMI
feedback)
PM is a random unitary
matrix
- -
LTE541
feature RL
RL25
dynamic
(1 or 2)
8
(4 + 4)
LTBF over
4 antennas of
a polarization
(4x4 covariance
matrix)
TM
TM82
cell edge
factor versus
2x2 MIMO
MIMO scheme
(over 2 logical antennas)
# antennas
#
streams
beamforming cell average
factor versus
2x2 MIMO
LTE541, DS-BF system level
moderate capacity gains
• BF + single stream = 3% 
• BF + dual stream = 26% 
large coverage gains
reference

Sounding in TD-LTE – Recommended Configuration
Impact of UE SRS BW on Beamforming performance
Legend:
C48 -> CSRS = 48 PRBs
B04 -> BSRS = 4 PRBs
EBB = Eigenvector Beamforming
• LL simulations for 10MHz, 48 PRBs SRS bandwidth & angular spread = 8°(i.e. environmental reflections cause
smaller signal path azimuth spread) show imroved performance of hybrid beamforming for slow moving UEs.
• Notable BF perf. gains
with wide UE SRS BW
for slow moving UEs with
small AS=8°
• No huge difference
between 12, 24 and 48
PRBs UE SRS BW
• Small or no
difference between
different UE SRS
BWs for faster
moving UEs and
small AS=8°
• Hardly any difference
between hybrid &
long term BF at all
How to read the
graph?
The graph shows
the simulated
SINR require-
ment for different
BLER values for
MCS20.
Therefore: the
lower the SINR
requirement for
a given BLER
(i.e. the further
left the curve),
the better the
performance.

• Same simulations for angular spread = 18°(i.e. environmental reflections cause higher signal path azimuth
spread) show smaller but still notable imrovement of hybrid beamforming performance for slow moving UEs.
• Notable gains with
wide UE SRS BW
for slow moving
UEs with wide
AS=18°
• 24 and 48 PRBs
UE SRS BW
clearly better than
12 PRBs
Simul. Assumptions ►
• Wider UE SRS BWs
for faster moving UEs
and or wider AS=18°
slightly better than
smaller UE SRS BWs.
• Hybrid BF slightly
better than LTBF

System LTE TDD
TDD frame configurations 2DL:1S:2UL, 3:9:2
System Bandwidth 10 MHz
Carrier Frequency (GHz) 2.6
Transport Block Size 12 PRBs
MCS MCS20 (16QAM, CR=0.75)
Spatial channel model Spatial Channel Model Extension (SCME)
Urban Macro Non-Line -Of-Sight 1 (UMaNLoS1)
Urban Micro Non-Line-Of -Sight (UMicroNLoS)
Velocity [km/h] 3 and 30 (70 Hz Doppler spread)
SRS configuration SRS bandwidth: 48 PRBs
SRS periosd (TSRS): 5ms, delay: 4 ms;
SRS Channel estimation real
SRS SNR 0 dB
DL Channel estimation ideal with perfect knowledge of the beamformer
Number of BS Antennas 8Tx/8Rx Uniform Linear Array (ULA)
Number of UE Antennas 1TX, 2RX
Antenna Pattern Omni
Simulation length >5000 subframes
Simulation Assumptions
• For the presented simulation results, the BF simulation assumptions were made as indicated in the table below.
• Note that only 1 UE was simulated, so the SRS performance degradation due to code multiplexing
in case of load increase was not considered!
Same noise level assumed for all
SRS bandwidths!
-> In reality wider band means higher
thermal noise, i.e. broader SRS BW
means reduced SRS performance.
◄ BACK
• Moreover, the impact of the
SRS bandwidth on SRS
performance was not
simulated but ignored, as
one and the same noise level
SNR=0dB was assumed for
all SRS bandwidth cases.

• System Level simulations for Beamforming comparing different UE SRS periodicities and UE SRS bandwidths
suggest differences of spectral efficiency among different beamforming scenarios as depcited below.
• However, due to currently unclear simulation assumptions these results can just be provide as a rough idea
how the aforemenmtioned factors/parameters impact the spectral efficiency for beamforming scenarios.
Reduced spectral efficiency in case of
increased doubled UE SRS periodicity
(2% reduction for average SE)
Increased spectral efficiency in case of
increased 4-fold UE SRS bandwidth
(3% increase for average SE).

Summary of CMCC BF gain field measurement
Velocity Position
BF Gain(dB)
0° 30° 60°
Stationary
Low 3.13 2.04 3.11
Mid 5.32 7.99 7.38
Far 4.78 8.97 11.22
Low
Low 2.88 2.20 7.88
Mid 2.93 4.25 8.13
Far 7.18 6.49 12.96
Medium
Low 3.64 2.38 3.45
Mid 5.85 3.43 9.89
Far 3.98 6.62 12.47
Dept. / Author / Date
• The result shows:
• Both in stationary and driving test,
smart antenna has different BF
Gain in different positions.
• As the table shows, there is no
big difference between the
stationary test and driving test in
the same position.
• Max BF Gain ≈ 12dB
• Min BF Gain ≈ 3dB
• Max BF Gain can be achieved in
the location 60°-Far. And it will
become lower as the decreased
angle or distance.
• Results coincided with the theory.
• BF gain evaluated as difference in
C-RS and D-RS rx power levels

39 © Nokia Siemens Networks 2011
_Change_Document_Information“ macro.
For internal use
Unique document identifier (ID) / Version number / Life cycle status
TM7 performance with diff. SRS period analysis
• For 96PRB，results show
10ms performance is better
than 40ms except low-mid.
• For 32PRB, 10ms
performance is better than
40ms obviously, especially
in the medium speed.
• The average performance
improvement for 10ms vs.
40ms is 17.5%.
• Summary: short period SRS
long period. Test results
answer to expectations.
L1 TP
BW Period Speed Position 10ms 40ms
10ms-
40ms
%
96RB -
Low
Near 27.16 23.88 3.28 13.70%
Mid 26.4 27.27 -0.87 -3.20%
Far 20.15 13.96 6.19 44.30%
Medium
Near 22.01 21.67 0.34 1.60%
Mid 21.87 21.01 0.86 4.10%
Far 18.48 14.81 3.67 24.80%
32RB -
Low
Near 23.25 22.38 0.87 3.90%
Mid 25.33 24.93 0.4 1.60%
Far 20.74 20.66 0.08 0.40%
Medium
Near 22.9 20.3 2.6 12.80%
Mid 24.99 19.28 5.71 29.60%
Far 19.19 10.91 8.28 75.90%

For internal use
TM7 performance with diff. SRS BW analysis
• About 60% of the test
results show 96RB conf.
32RB. 25% is no big diff. .
And another 15% show
96RB performance is
worse.
• Over all, 96RB conf.
performance is better.
• Summary: generally,
bigger SRS bandwidth
should get a better
performance. But it is not
absolute. Test results
answer to the perspective.
L1 TP/Mbps
BW Period Speed Position 96RB 32RB
96RB-
32RB
%
- 10ms
Low
Near 27.16 23.25 3.91 16.80%
Mid 26.4 25.33 1.07 4.20%
Far 20.15 20.74 -0.59 -2.80%
Mediu
m
Near 22.01 22.9 -0.89 -3.90%
Mid 21.87 24.99 -3.12 -12.50%
Far 18.48 19.19 -0.71 -3.70%
- 40ms
Low
Near 23.88 22.38 1.5 6.70%
Mid 27.27 24.93 2.34 9.40%
Far 13.96 20.66 -6.7 -32.40%
Mediu
m
Near 21.67 20.3 1.37 6.70%
Mid 21.01 19.28 1.73 9.00%
Far 14.81 10.91 3.9 35.70%

For internal use
TM7 performance with diff. speed
• Low speed TM7
performance is better
than medium speed
exclude 96RB-40ms
conf..
• Compared with
medium speed TP, low
speed TP has 18.9%
improvement in
average.
• Summary: with the
same SRS period and
BW, TM7 performance
with low speed is
better than medium
speed. Results answer
to the expectations.
L1 TP/Mbps
BW Period Speed Position Low Medium
Low -
Medium
%
96RB 10ms -
Near 27.16 22.01 5.15 23.40%
Mid 26.4 21.87 4.53 20.70%
Far 20.15 18.48 1.67 9.00%
96RB 40ms -
Near 23.88 21.67 2.21 10.20%
Mid 27.27 21.01 6.26 29.80%
Far 13.96 14.81 -0.85 -5.70%
32RB 10ms -
Near 23.25 22.9 0.35 1.50%
Mid 25.33 24.99 0.34 1.40%
Far 20.74 19.19 1.55 8.10%
32RB 40ms -
Near 22.38 20.3 2.08 10.20%
Mid 24.93 19.28 5.65 29.30%
Far 20.66 10.91 9.75 89.40%

Outline
• Overview
• Parameters

LTE541, DS-BF
parameters
Short
Name
Description
Range / Step-
size
Defaul
t
Value
Paramete
r scope
Remark
dlBeam
Formin
gAlgorit
hm (O)
BF algorithm Hybrid (0), Long
term (1), Short
term (2)
Hybrid
(0)
cell
dlSecto
rBeamf
orming
Weight
Mode
(O)
DLSector BF
Weight Mode for
sector beam
solution 1
8 pipe CMCC
mode (0), 8 pipe
NSN mode (1), 2
pipe mode (2), 4
pipe mode (3)
8 pipe
CMCC
mode
(0)
cell sector beam weights for
• CMCC mode: see LTE493
presentation
• NSN mode for test purposes
• 2 antennas: (1 0 0 0) identical to
single antenna element
• 4 antennas: (1 1 0 0)
timeChI
nfoValid
(O)
maximum time
during which the
measurement
channel
information is
regarded as valid
invalid (0), 10ms
(1), 20ms (2),
50ms (3), 100ms
(4), 200ms (5),
500ms (6),
1000ms (7),
1500ms (8),
2000ms (9),
infinite (10)
200ms
(5)
cell • invalid (0) => measurement
channel information is always
invalid
•infinite (10) => measurement
channel information is always
valid
V = vendor specific O = operator specific

LTE541, DS-BF
parameters for fall back to TxDiv
Short
Name
Description
Range /
Step-size
Default
Value
Paramete
r scope
Remark
actBfFa
llback
(O)
activation of fall
back from TM8 to
TxDiv
false, true true cell If 'true', then mimoBfslCqiThU
and mimoBfslCqiThD must be
configured
mimoBf
slCqiTh
D (O)
CQI value
threshold for
switching from
TxDiv to SS-BF
0...16, step
0.1
12 cell parameter is not only related to
UCA
mimoBf
slCqiTh
U (O)
CQI value
threshold for
switching from SS-
BF to TxDiv
0...16, step
0.1
14 cell parameter is not only related to
UCA
cqiCom
pTdRi2
Cl (V)
CQI compensation
for DL AMC if TX
div is used and RI
with value 2 is
received
0...10, step
0.1
3 BTS parameter is applicable if CL
MIMO SM was configured
(dlMimoMode set to 4)

LTE541, DS-BF
parameters
Short
Name
Descript
ion
Range /
Step-size
Defa
ult
Valu
e
Para
meter
scope
Remark
dlMimoM
ode (O)
DL
MIMO
mode for
each
physical
channel
SingleTX
(0), TXDiv
(1), Static
Open Loop
MIMO (2),
Dynamic
Open Loop
MIMO (3),
Closed Loop
Mimo (4),
Single
Stream
Beamformin
g (5), Dual
Stream
Beamformi
ng. (6)
TXDi
v (1)
Cell • 0: used by all physical DL channels
• 1: used by all physical DL channels
• 2:
– DS SM MIMO for SRB1 (DCCH) and RBs(DTCH) on
PDSCH
–SS DL Transmit Diversity for SRB0 (CCCH), BCCH
and PCCH on PDSCH and all other physical channels
• 3:
– depending on radio conditions either SS DL TxDiv or
DS SM MIMO for SRB1 (DCCH) and RBs(DTCH) on
PDSCH
– SS DL TxDiv for SRB0 (CCCH), BCCH and PCCH on
PDSCH and all other physical channels
• 4:
–Dynamic CL MIMO: SRB1 (DCCH) and RBs(DTCH)
on PDSCH are transmitted using either SS DL TxDiv or
SS or DS MIMO with CL SM depending on radio
conditions and UE category; SRB0 (CCCH), BCCH and
PCCH on PDSCH and all other physical channels are
transmitted using SS DL TxDiv

LTE541, DS-BF
parameters for dynamic rank switching
Short
Name
Description
Range /
Step-size
Defau
lt
Value
Paramete
r scope
Remark
bfCqiThUp
(O)
TM8 CQI threshold
for switching from
SS-BF to DS-BF
0...16, step
0.1
11 cell
bfCqiThDo
wn (O)
TM8 CQI threshold
for switching from
DS-BF to SS-BF
0...16, step
0.1
9 cell
bfRankThU
p (O)
TM8 rank threshold
for switching from
SS-BF to DS-BF
1...2, step
0.05
1.6 cell
bfRankThD
own (O)
TM8 rank threshold
for switching from
DS-BF to SS-BF
1...2, step
0.05
1.4 cell

LTE541, DS-BF
parameters for dynamic rank switching (filtering)
Short
Name
Description
Range /
Step-size
Defau
lt
Value
Paramete
r scope
Remark
mimoBfCqi
Avg (O)
Averaging filter
constant for CQI
measurements in
DS-BF
0.05...1,
step 0.05
0.5 cell filtering of “mimoCQI”
mimoBfdlRi
Avg (O)
Averaging filter
constant for RI
measurements in
DS-BF
0.05...1,
step 0.05
0.5 cell filtering of “mimoRANK”

Downlinksubframe
0l 6l 0l 6l
even-numbered slots odd-numbered slots
7R7R7R7R
7R7R7R7R
7R7R7R7R
0l 6l 0l 6l
even-numbered slots odd-numbered slots
8R 8R8R 8R
8R 8R8R 8R
8R 8R8R 8R
Antenna port 7 Antenna port 8
Antenna port 7
Specialsubframewith
configuration3,4,or8 0l 6l 0l 6l
7R7R
7R7R7R7R
7R7R7R7R
Antenna port 8
0l 6l 0l 6l
8R 8R8R 8R
8R 8R8R 8R
8R 8R8R 8R
7R7R
Specialsubframewith
configuration1,2,6,or7
0l 6l 0l 6l
7R7R 7R7R
7R7R 7R7R
7R7R 7R7R
0l 6l 0l 6l
8R 8R 8R 8R
8R 8R 8R 8R
8R 8R 8R 8R
• used for channel estimation
• mapping to physical REs
according to 6.10.3.2 of [3GPP-
36.211]
• REs depend on special subframe
configuration
• DwPTS in special subframe
configuration 0 and 5 not used
• same positions for port 7 and 8
LTE541, DS-BF
DRS

---- 8pipe Calibration
1. Mandatory for BF working
2. BBU generate and send calibration signal
3. BBU process the received calibration signal and compensate
phase or gain error
4. RRU provide 4 modes, RX; TX; Cal-RX; Cal-TX
Training Sequence for Calibration
1symbol
15 KHz

---- 8pipe Calibration
Converter RRU
Ant 4,5,6,7
Ant 0,1,2,3
BBU
Ant 2,3
Ant 4,5
Ant 6,7
Ant 0, 1RF1
RF2
RF3
RF4
Flexi
System
Module
Cal
Cal
RRU
OBSAI-CPRI converter
Column
#1 #2 #3 #4
CPRI, 2x6Gbit/s
OBSAI, 4x3Gbit/s

F01 beam forming_srs

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to F01 beam forming_srs

Similar to F01 beam forming_srs (20)

Recently uploaded

Recently uploaded (20)

F01 beam forming_srs