Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Application Note

Base Station Analyzer

LTE PHY Layer Measurement Guide

WEBSITE: www
...
com/test

Base Station Analyzer

Application Note: LTE PHY Layer Measurement Guide

Contents
Understanding LTE
...
3
LTE Physical Layer
...
4
Frame Structure
...
7
Cyclic Prefix
...
10
Physical Downlink Shared Channel (PDSCH)
...
11
Physical Downlink Control Channel (PDCCH)
...
13
Physical Broadcast Channel (PBCH)
...
14
Reference Signal
...
16
LTE Downlink Map
...
19
Base Station Analyzer
...
21
Base Station Analyzer Measurement
...
23
Channel Power
...
Time
...
26
Modulation Accuracy Measurement
...
28
Subframe Summary
...
34
Control Channel Summary
...
37
Unwanted Emission
...
39
ACLR
...
42
Over the Air Analysis
...
44
Datagram
...
46
References
...
The eNBs provide the user interface towards mobile phones
and devices, and they are interconnected with each other through X2 interfaces; and, they are connected to
the backhaul or evolved packet core (EPC) through S1 interfaces
...


• local mobility anchor for
inter-eNB handover, inter-3GPP
mobility
• E-UTRAN idle mode downlink
packet buffering and initiation of
network-triggered service request
procedure
• lawful interception
• packet routing and forwarding
• transport-level packet marking in
the uplink and the downlink
• accounting on user and QCI
granularity for inter-operator
charging
• UL and DL charging per UE,
PDN, and QCI
...

Figure 1
...
2)

LTE Physical Layer
The multiple access schemes in LTE use orthogonal frequency division multiple access (OFDMA) with a
cyclic prefix (CP) in the downlink and single carrier frequency division multiple access (SC-FDMA) with a
cyclic prefix in the uplink
...
The uplink user specific allocation is continuous; it enables single-carrier
transmission while the downlink uses resource blocks which are spectrum independent
...
4 MHz and 20 MHz
depending on the available spectrum
...
The 20 MHz bandwidth downlink in a 2 x 2 MIMO configuration can
provide a downlink data rate up to 150 Mbps, and 300 Mbps with 4 × 4 MIMO configuration
...


Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

4

Up to 20 MHz
Uplink

SC-FDMA

Downlink

OFDMA

Figure 2
...
4

3

5

10

15

20

Transmission bandwidth [MHz]
1
...
7
4
...
5
18
Transmission bandwidth [RB] 6 15 25 50 75 100


Table 1
...

Channel Bandwidth [MHz]
Transmission Bandwidth Configuration [RB]

Channel edge

Resource block

Channel edge

Transmission
Bandwidth [RB]

Active Resource Blocks

Center subcarrier (corresponds to DC in
baseband) is not transmitted in downlink

Figure 3
...
3)

Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

5

Due to unused subcarriers, the transmission bandwidth is smaller than the channel bandwidth
...
Therefore, a 5 MHz signal can
e
transmit 27
...
However, 25 resource blocks are used for the 5 MHz LTE channel
and it occupies 4
...
For that reason, transmission bandwidth is the reference for all
measurements excluding occupied bandwidth measurements
...
5 kHz interval
...
A resource block is the minimum
allocation unit for system resource allocation and the transmission bandwidth is obtained by the number of
resource blocks (n) multiplied by 180 kHz (bandwidth per RB)
...
In the time domain, one LTE frame
has a 10 ms period and consists of 20 slots of 0
...
A subframe is defined as two consecutive slots
...
LTE frame structure

Slot (10MHz) = 50 RB
9MHz (BW) / 15kHz (Sc) = 600 Sc
600 Sc / 12 Sc (RB) = 50 RB

Base Station Analyzer

6

Application Note: LTE PHY Layer Measurement Guide

The representation of a LTE timeslot in a configuration of ∆f at 15 kHz and the cyclic prefix (CP) is normal
...
Therefore, one LTE frame consists of 20 slots each allocating 1 RB (7 symbols) in time
and 10 MHz channel bandwidth transports 50 RB (9 MHz/15 kHz/12), or 1000 RB per frame (50 x 20), or
84000 RE per frame (1000 x 84), where an RE is the minimum unit for data allocation and power control
...

Channel Bandwidth [MHz]

1
...
08
2
...
92
3
...
84)
FFT size (No
...
5208
0
...
5
9
0
...
68
15
...
84) (4x3
...
1302
0
...
5

18

23
...
84)
1536
0
...
72
(8x3
...
0326
15,360

* TS period= 1/(sampling frequency)
* No
...
5 ms/TS period


Table 2
...




Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

7

Resource Block
Resource blocks (RB) are used to describe the mapping of physical channels to resource elements (RE)
...


t

o

l

One downlink slot T
s

DL
N symb OFDM symbols
DL RB
k = N RB N sc − 1

RB
N sc subcarriers

DL
RB
N RB × N sc subcarriers

Resource block
DL
RB
N symb × N sc resource elements

Resource element (k , l )

k =0

l=0

l=

DL
N symb

−1

Figure 5
...
1)

A physical resource block (RB) is defined as set of 7 consecutive OFDM symbols in the time domain and 12
consecutive subcarriers (SC) in the frequency domain
...


Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

Configuration NSCRB

NsymbDL

Normal cyclic prefix

Δf = 15 kHz

12

7

Extended cyclic

Δf = 15 kHz

6

prefix

Δf = 7
...
Physical resource blocks parameters (Ref
...

In case of multi-antenna transmission, there is one resource grid defined per antenna port
...
The set of antenna ports supported depends on the reference
signal configuration in the cell:
• cell-specific reference signals, associated with non-MBSFN transmission, support a configuration of one,
two, or four antenna ports
• MBSFN reference signals, associated with MBSFN transmission, are transmitted on antenna port 4
• UE-specific reference signals are transmitted on antenna port 5
...
Data symbol periods
become shorter as the data rate becomes larger since the symbol period is inversely proportional to the data
rate or 1/(data rate)
...

It is known that ISI negatively affects the beginning part of each symbol and distorts data
...
Distortion of received signal due to ISI

A relatively long OFDM symbol period should resist the multipath environment
...
By increasing the CP ratio (CP
length to effective symbol length), the system becomes more robust against multipath however it results in a
decreased data capacity
...
Symbol structure

When the subcarrier spacing is 15 kHz, the length of the effective symbol becomes 1/ 15 kHz ≈ 66
...
For
normal CP, one timeslot is composed of 7 symbols and as a result a LTE frame consists of 140 symbols (7
symbols x 20 slots)
...
33 ms
...
5 kHz
...
The number of TS increases as the channel bandwidth increases
...

Bandwidth
Configuration (downlink)
Length of CP
TS μsec

20 MHz

normal CP

∆f = 15K Hz

160 for = 0

5
...
,6 4
...
667



∆f = 7
...
333

15 MHz

∆f = 15 KHz

120 for = 0

5
...
,6
4
...
667



extended CP

∆f = 7
...
333

10 MHz

∆f = 15 KHz

80 for = 0

5
...
,6
4
...
667



extended CP

∆f = 7
...
333

5 MHz

∆f = 15 KHz

40 for = 0

5
...
,6

4
...
667



∆f = 7
...
333

3 MHz

∆f = 15 KHz

20 for = 0

5
...
,6
4
...
667



extended CP

∆f = 7
...
333

1
...
208

normal CP

9 for = 1,2,
...
6875


extended CP



∆f = 15 KHz

32 for = 0,1,…,5

16
...
5 KHz

64 for = 0,1,2

33
...
CP lengths and Ts occupation for each channel bandwidth

Base Station Analyzer

Application Note: LTE PHY Layer Measurement Guide

10

The symbol lengths and Ts numbers for different channel bandwidths are illustrated in the following figure
...
Thus, the length of TS is proportional to
the sampling rate
...
5 KHz, extended CP
Figure 8
...
212 and 36
...
The following physical
channels are defined for LTE PHY downlinks
...
The same 1
ms long and 180 kHz wide resource block is the fundamental data scheduling unit
...
The base station (eNB) carries out the
resource allocation based on the channel quality indicator (CQI) from the LTE terminal
...


Figure 9
...
4 MHz

The modulation format of PDSCH channels may be QPSK, 16 QAM or 64 QAM
...

Physical channel

Modulation schemes

PDSCH

QPSK, 16QAM, 64QAM
Table 5
...

This can vary between one and three for each 1 ms subframe
...


Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

12

An extreme situation is illustrated in the following figure where the PDCCH allocation is changed from one
symbol to three symbols
...
5 ms slot in the 1 ms subframe, thus the overhead change from 1/14 to 3/14 of the total physical layer
resource space
...

Physical channel

Modulation scheme

PCFICH

QPSK
Table 6
...
PDCCH resource allocations from PCFICH

Physical Downlink Control Channel (PDCCH)
The LTE user equipment will obtain from the control channel (PDCCH) the uplink and downlink resource
allocations it may use
...

A CCE corresponds to nine resource element groups
...

The control channel (PDCCH) containing shared information (PDSCH) is often referred to as the downlink
assignment
...


Physical channel

Modulation scheme

PDCCH

QPSK
Table 7
...
1)

Base Station Analyzer

Application Note: LTE PHY Layer Measurement Guide

13

Physical Hybrid ARQ indicator Channel (PHICH)
The task for the HARQ indicator channel (PHICH) is simply to indicate in the downlink whether an uplink
packet was correctly received or not
...

Physical channel

Modulation schemes

PHICH BPSK




Table 8
...
1)

HARQ feedback seen by the UE

PDCCH seen by the UE

UE behaviour

ACK or NACK
new transmission new transmission according to PDCCH
ACK or NACK
retransmission
retransmission according to PDCCH (adaptive
retransmission)
ACK
none

no (re)transmission, keep data in HARQ buffer and a

PDDCH is required to resume retransmissions
NACK
none
non-adaptive retransmission



Table 9
...
2)

Physical Broadcast Channel (PBCH)
The broadcast channel (PBCH) carries the system information needed to access the system, such as random
access (RACH) parameters required for initial network access and UE uplink time synchronization with
the eNB
...
08 MHz bandwidth, as shown in the following figure, so
the broadcast channel (PBCH) structure is independent of the actual system bandwidth being used
...
4 MHz system bandwidth, there are no resource blocks on either side of the broadcast channel (PBCH) in
the frequency domain in use so effectively only six resource blocks may be used to meet the spectrum mask
requirements
...
PBCH location at the center frequency

Base Station Analyzer

Application Note: LTE PHY Layer Measurement Guide

Physical channel

Modulation scheme

PBCH

14

QPSK




Table 10
...

Physical channel

Modulation schemes

PMCH

QPSK, 16QAM, 64QAM




Table 11
...
User equipment
(UE) may assume downlink cell-specific reference signal (RS) energy per resource element (EPRE) to be
constant across the downlink system bandwidth and constant across all subframes until different cell-
specific reference signal (RS) power information is received
...
The downlink RS transmit power is defined as the linear average over
the power contributions (in [W]) of all resource elements that carry cell-specific RSs within the operating
system bandwidth
...

The downlink RSs consist of known reference symbols inserted in the first and third last OFDM symbol of
each slot
...
The number of downlink antenna ports
equals 1, 2, or 4
...
There are three different twodimensional orthogonal sequences and 170 different two-dimensional pseudo-random sequences
...


Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

15

Cell Specific Reference Signals
Cell-specific reference signals shall be transmitted in all downlink subframes in a cell supporting nonMBSFN transmission
...
(Ref 1)
Cell-specific reference signals are transmitted on one or several of antenna ports 0 to 3
...
Mapping of downlink RSs for SISO (Ref
...

MBSFN reference signals are transmitted on antenna port 4
...
Mapping of MBSFN RSs (extended cyclic prefix Δf = 15 KHz) (Ref
...
The UE is informed by higher layers whether
the UE-specific reference signal is present and is a valid reference for PDSCH demodulation
...


Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

1
1
2
3
4
5
6
7
8
9
10
11
12

2

3

4

5

6

7

8

9 10 11 12 13 14

R5
R5

R5
R5

R5
R5

R5
R5

R5
R5

R5
R5

(a) Normal cyclic prefix

1
1
2
3
4
5
6
7
8
9
10
11
12

2

3

4

5

6

7

8
R5

16

9 10 11 12

R5

R5
R5

R5

R5
R5

R5

R5
R5

R5

R5

(b) Extended cyclic prefix

Figure 14
...
The primary synchronization signal (P-SS) and secondary synchronization signal
(S-SS) jointly define 504 unique physical-layer cell identities (PCIs)
...
P-SS and S-SS occupy 1
...


Figure 15
...
Therefore, it is more intuitive to display the downlink frame with a two-dimensional
diagram
...

As shown in the diagram, the primary synchronization channel (P-SCH) carrying P-SS and the secondary
synchronization channel (S-SCH) carrying S-SS are placed in the latter symbols of TS0 and TS10 occupying
1
...

User equipment (UE) can get synchronized with the base station by monitoring the downlink signal during
5 ms for the 1
...

The broadcast channel (PBCH) is located at the beginning of TS1 or the second timeslot on the first
subframe and also occupies 1
...
This scheme enables the UE to get information about the
base station
...


ormal CP
Sub-Carrier
Frequency allocation=15 KHz with

Reference signal (RS_Pilot)
PBCH
S-SCH
P-SCH
Resource block

03
Slot
0
...
5 ms
1 Sub-Frame
1ms

06
Slot
0
...
5 ms
1 Sub-Frame
1 ms

04
Slot
0
...
5 ms

1 Sub-Frame
1 ms

1

CP

09
Slot
0
...
5 ms

CP

11
Slot
0
...
5 ms
1 Sub-Frame
1 ms

12
Slot
0
...
5 ms

5

1 Sub-Frame
1 ms

15
Slot
0
...
5 ms

1 Sub-Frame
1 ms

CP

16
Slot
0
...
5 ms

1 Sub-Frame
1 ms

18
Slot
0
...
5 ms

1 Sub-Frame
1 ms

F
R
E
Q
U
E
N
C
Y

Figure 16
...
5 ms

PDCCH

00
Slot
0
...
OFDMA allows dynamic resource allocation to the system
...

• transmitted signal modulation quality, also known as error vector magnitude (EVM) requirements
...

• unwanted emissions, for inside and outside the operating band
...

To ensure the performance of LTE transmitters based on the above three categories, 3GPP recommends
performing the following tests for LTE-FDD base stations:
•
•
•
•
•
•
•
•
•
•

base-station output power
output power dynamic
frequency error
modulation quality metric using error vector magnitude (EVM)
MIMO time alignment between transmitter’s branches
downlink reference signal power
occupied bandwidth
adjacent channel leakage power ratio (ACLR)
operating band unwanted emissions
transmitter’s spurious emissions
...
The key measurement functions supported
by the Base Station Analyzer are the following:
• spectrum analyzer
• cable and antenna analyzer
• power meter
• interference analysis
• channel scanner
• backhaul analysis (E1, T1, Ethernet)
• Signal analysis for the following technologies:
- cdmaOne/CDMA2000
- EV-DO
- GSM/ GPRS/ EDGE
- WCDMA/HSDPA
- TD-SCDMA
- Mobile WiMAX
- LTE-FDD and LTE-TDD
...
The Base Station Analyzer measurement summary is as follows:
•
•
•
•
•







•




channel power
occupied bandwidth
spurious emission mask (SEM)
adjacent channel leakage power ratio (ACLR)
signal quality analysis (demodulator)
- data channel summary
- control channel summary
- subframe summary
- frame summary
- power vs
...
T)
- complementary cumulative distribution function (CCDF)
- MIMO time alignment
Over the air analysis
- ID scanner
- downlink datagram
- control channels

Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

21

The following table shows the relationship between the Base Station Analyzer tests and 3GPP’s requirements
...


P vs
...

Output power dynamic
CCDF
statistical distribution of OFDMA
symbol power
...

subframe summary

frame summary



error vector
data channel summary
magnitude


control channel summary


modulation quality of all resource
blocks of a defined subframe
...



subframe summary
modulation quality of all channels
in a defined subframe
...


time alignment


time alignment error
(MIMO)


time difference between antenna 0
(RS-0) and antenna 1 (RS-1)
...


subframe summary
power level of all channels

contained on a defined subframe

frame summary
power level of all channels
contained on a frame
...

operating band
SEM
unwanted emission at the out of
unwanted emission channel
...

Table 12
...
A reference to the applicable test model is made in each test
...

The physical channels power setting is defined by the physical channel of energy per resource element
(EPRE) relative to the reference signal
...
5 dB
...

Measurement item

E-TM



E-TM

BS output power
■
Total power dynamic range
Occupied Bandwidth
■
ACLR
■ ■
Operating band unwanted emission ■
■
Transmitter intermodulation
■
RS absolute accuracy
■
EVM
QPSK

16 QAM

64 QAM

(single PRB)
Frequency error
*note 1: at minimum power condition
*note 2: at maximum power condition


E-TM

E-TM

E-TM

E-TM

1
...
2 2 3
...
2
3
...
E-UTRA test model applicability map

Base Station Analyzer Measurement Setup
The following parameters should be properly set on the Base Station Analyzer to test and measure the LTE
transmitter:
•




•

Trigger—four types of trigger modes are available
- Internal—sets the trigger to internal reference
- External—sets the trigger to external reference
- GPS—sets the trigger to built-in GPS receiver
- Free—sets the trigger mode to free run
Subframe No
...
The PHICH group number is equal for all subframes where Ng Є {1/6, 1/2, 1, 2}
...
The relation between PHICH
group and Ng for 10 MHz channel bandwidth is described in the following table
...
PHICH group numbers

• # of CFI—sets the number of OFDMA symbols set in a subframe where a symbol set refers to all
subcarriers that belong to the same symbol
• Cyclic Prefix—sets the type of cyclic prefix as normal or extended
• Cell ID—sets the identifier of the cell site under test
...
The automatic (Auto) setting allows the
instrument to obtain the cell-ID from the received signal
...


Power Measurement
There are two required measurements defined by 3GPP: base station output power and total power dynamic
range
...

Power measurements can be done in the following tests depending on the base station power performance
characteristic
...
time (P vs
...


Channel Power
Channel power measures the base station’s transmitting power in the frequency domain
...


Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

24

The following figure shows the channel power measurement result of an LTE DL signal where the
transmission bandwidth is 9 MHz corresponding to 10 MHz channel bandwidth
...


Figure 17
...
1)

Under the trace, the resulting channel power is displayed with the integral bandwidth
...

In the Channel Power function, the following Base Station Analyzer parameters are set as default values
...


Power vs
...
Time (P vs
...
In P vs
...

Additional information is presented by the Base Station Analyzer such as cell identity, I-Q offset, time offset,
subframe, and frame power
...
Power vs
...
1

•
•
•
•
•
•
•
•

Frame Power—the average power of a full LTE frame
Subframe No—the number of the specified subframe
Cell ID—the cell identity
I-Q Origin offset—shows the relative DC offset of I and Q symbols in dB scale on the reference of average
voltage of received symbols
Time Offset—shows the time difference between timing reference and frame sync
Subframe Power—the averaged power of the specified subframe
First Slot Power—the averaged power of the first timeslot in the specified subframe
Second Slot Power—the averaged power of the second timeslot in the specified subframe
...
T function, the following parameters are set as default values on the Base Station Analyzer
...

The following Base Station Analyzer settings may affect the measurement accuracy, thus some
consideration is recommended
...
Offset—may affect the overall measurement accuracy
• Cyclic Prefix—may affect the subframe and slot power accuracy
• RF in Loss—may affect the overall power measurement accuracy
...
CCDF is not a mandatory measurement for installation, but it is a useful parameter to
optimize the base station output power covering a wide area without degrading QoS during operation
...
A high performance amplifier ensures QoS, but it incurs installation, operation, and
maintenance costs
...

The following figure shows the CCDF measurement result of the Base Station Analyzer for E-UTRA TM1
...

A Gaussian distribution curve is displayed as a reference line
...
CCDF measurement for TM1
...
Power—the average power of specified symbol measured over the signal bandwidth
Max Power—the highest power among the measured data
Crest factor—obtained by subtracting Avg
...
For example, if 4 dB is 9
...
64% of measured power data are lower than
4 dB of the average power
...

The following Base Station Analyzer settings may affect the measurement accuracy and some consideration
is recommended
...
Offset—affects the overall measurement accuracy
• RF In Loss—affects the accuracy of Avg
...


Modulation Accuracy Measurement
The purpose of base-station demodulation performance requirements is to estimate how the network is
performing and to verify possible eNB impairments that can cause network degradation
...

3GPP recommends modulation-specific error vector magnitude (EVM) requirements to ensure highquality signals of the eNB
...

The EVM requirement ensures that the downlink throughput due to the non-ideal waveform in the eNB is
only marginally reduced, typically by 5% assuming an ideal reception in the UE
...

It is known that the following factors affect the modulation accuracy of transmitters:
• carrier rejection—as the measurement is made after ZF-equalization, the Base Station Analyzer partially
removes this contribution
...
At low output power, a
small DC offset in the TX chain generates high carrier leakage to a point where the transmission power
control (TPC) accuracy may not be within specifications
...

• even-order distortion—even order non-linearity contributes mainly to adjacent channel leakage ratio
(ACLR) as the main effect is to enlarge the transmitted spectrum
...

• local oscillator phase noise—the induced jitter generates phase error in the modulation constellation, thus
contributing to EVM
• power-amplifier distortion—amplifier distortion has a contribution to EVM and also generates
asymmetrical spectral energy in the adjacent channels
• image—the signal image generated by the quadrature imperfections in the up-mixing process can be
considered as band noise contributing to the TX signal-to-noise ratio (SNR)

Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

28

• group-delay distortion—LTE has an I/Q BW of 5 MHz for 30 MHz duplex distance or 10 MHz for 80 MHz
duplex distance
...

Overall, the LTE EVM specification requires special attention to the higher bandwidth and smaller duplex
distances
...

The Base Station Analyzer satisfies the requirement of 3GPP for modulation accuracy measurement for LTE
signals
...


Frame Summary
3GPP recommends that EVM should be taken from the shared channel (PDSCH) in a frame excluding
control channels and reference signals
...

The following figure shows the Base Station Analyzer Frame Summary measurement screen for E-UTRA
TM3
...


Figure 20
...
2)

Base Station Analyzer

Application Note: LTE PHY Layer Measurement Guide

29

The Base Station Analyzer Frame Summary measurement consists of three sections: the upper section for
error summary, the middle section for channel status, and the lower section for power metrics
...
Error summary in Frame Summary screen

The above figure shows the error summary where each parameter is defined as follows:
• EVM RMS—the averaged EVM for all resource elements (RE) allocated including control, data channels,
and reference signal
• EVM Peak—the EVM for a specific RE which has the worst EVM
...

• Data EVM RMS—the averaged EVM for all RE allocated for shared channels (PDSCH)
...
104
...

Modulation scheme for PDSCH

Required EVM [%]

QPSK
16 QAM
64 QAM

17
...
5%
8%


Table 15,ljklll
...
3)

• 3GPP requires that data EVM measurements should be performed with TM2, TM3
...
2 and TM3
...

• Data EVM Peak—the EVM for a specific RE allocated for PDSCH with the highest EVM
...

• Frequency Offset—the difference between the frequency of the subcarrier and the user defined center
frequency
...
05 ppm observed over a period of one subframe (1 ms)
...


Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

30

It is useful to consider the relationship between the measurement result and the channel configuration
of E-TM because it is important to verify the eNB performance with the E-TMs defined by 3GPP
...
2 for various channel bandwidths
...
4 MHz 3 MHz

5 MHz

10 MHz 15 MHz 20 MHz

Reference, Synchronization Signals
RS boosting, PB = EB/EA 1 1 1 1 1 1
Synchronisation signal EPRE/ERS [dB]
0
...
573 2
...
426 3
...
426
Reserved EPRE/ERS [dB]

-inf -inf -inf -inf -inf -inf

PBCH EPRE/ERS [dB]

0
...
573 2
...
426 3
...
426

PBCH

Reserved EPRE/ERS [dB]

-inf -inf -inf -inf -inf -inf

# of symbols used for control channels

2

PCFICH
1

1

1

1

1

PCFICH EPRE/ERS [dB] 3
...
010 -3
...
010 -3
...
010 -3
...
792 2
...
880 1
...
488 1
...
005 (*)
1
...
426 2
...
005 2
...
e
...



Table 16
...
2

Base Station Analyzer

Application Note: LTE PHY Layer Measurement Guide

31

In the case of LTE signals of 10 MHz, it is advisable to compare the value of each parameter with the resulting
value displayed in the Base Station Analyzer Frame Summary measurement
...


Figure 22
...
From the values shown in table 13:
- RS boosting is defined as PB = EB/EA= 1, thus the RS power should be 0 dB
- Sync Signal is defined as synchronization signal EPRE/ERS [dB] = 2
...
426 dB
- PBCH EPRE ERS [dB] = 2
...
426 dB
- PCFICH EPRE ERS [dB] = 0, thus the PCFICH power should be 0 dB
- PHICH group EPRE ERS [dB] = 0, thus the PHICH power should be 0 dB
- PDCCH REG EPRE ERS [dB] = 1
...
065 dB
- For 16 QAM-modulated PDSCH, PRB PA = EA/ERS [dB] = -3, thus the PDSCH power should be 3 dB
lower than RS
- For QPSK-modulated PDSCH, PRB PA = EA/ERS [dB] = 2
...
426 dB
higher than RS
...

In the Summary function, the following JD7105A parameters are set as default values on the Base Station
Analyzer
...


Base Station Analyzer

Application Note: LTE PHY Layer Measurement Guide

32

The following Base Station Analyzer settings may affect the measurement accuracy, thus some
consideration is recommended:
• Freq
...


Subframe Summary
The Subframe Summary function analyzes the LTE frame in detail
...
In
addition, the Subframe Summary provides modulation errors, power and resource allocation status of all
channels contained in a specific subframe
...

Note: Some control channels were not transmitted in the selected subframe thus the measurement result may
remain blank
...
Subframe Summary measurement for E-TM3
...


Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

33

The Subframe Summary measurement parameters are defined as follows:
• EVM RMS—the averaged EVM for all resource elements (RE) allocated including control, data channels,
and reference signal
• EVM Peak—the EVM for a specific RE which has the worst EVM
...

• Data EVM RMS—the averaged EVM for all RE in the subframe allocated for PDSCH
• Data EVM Peak—the EVM for a specific RE in the subframe allocated for PDSCH with the highest EVM
...

• Frequency Offset—the difference between the frequency of the subcarrier and the user-defined center
frequency
...
05 ppm+12Hz)

• IQ Origin Offset—the relative offset of I and Q symbol in dB based on received symbols average voltage
• Cell ID—the eNB identity number
• Group ID—the eNB identity group number where there are 168 cell-identity groups and each group
consists of three identity numbers
• Sector ID—the cell-identity number within the Cell-Identity group (0, 1 or 2)
...
Physical channel summary on Subframe Summary (E-TM3
...

• RBW—100 kHz
• Attenuation—Auto
...

•
•
•
•

Freq
...


Data Channel Summary
The Data Channel Summary function shows the power of each resource block (RB) and modulation quality
of each RB with its corresponding constellation diagram
...

The following figure shows the Base Station Analyzer Data Channel Summary measurement screen
...


Figure 25
...
2)

In the resource block power diagram, the power of each resource block is displayed as a color code where
the color index is located at the right side of the diagram
...
Resource block power diagram in Subframe Summary measurement

The Resource Block is selectable on the Base Station Analyzer by pressing [Marker]-[Knob/Arrow] key
...
The reference level and minimum level of
the power index is linked with the amplitude setting
...
Since the EVM calculation is done for each RE, the location of worst RE is
displayed with the EVM peak
...
I-Q diagram in the Subframe Summary measurement

The I-Q diagram parameters in the Subframe Summary measurement are defined as follows:
• RB Power—the averaged power of all REs in the selected RB over one subframe period
...
In case of a 10 MHz LTE frame, there are 50 RBs in the
frequency domain thus if all RB have the same power then the RB power is about 10log(1/50)= -17 dB
lower than the subframe power
...
It is also displayed the location
of the worst RE
...

• RBW—100 kHz
• Attenuation—Auto
...

• Freq
...


Control Channel Summary
The Control Channel Summary function shows the status of control channels and reference signals for a
defined subframe including the corresponding constellation diagram of a selected channel
...

The I-Q Diagram section shows the power and modulation format of the highlighted channel
...
Control Channel Summary measurements

In the Channel Summary section, channels can be selected by pressing the [Marker]-[Knob/Arrow]
key
...


Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

37

The power of each channel is defined as follows:
•
•
•
•
•
•

P-SS power [dB] = (primary synchronization signal EPRE)/ERS [dB]
S-SS power [dB] = (secondary synchronization signal EPRE)/ERS [dB]
PBCH power [dB] = PBCH EPRE/ERS [dB]
PCFICH power [dB] = PCFICH EPRE/ERS [dB]
PHICH power [dB] = PHICH Group EPRE/ERS [dB]
PDCCH power [dB] = PDCCH REG EPRE/ERS [dB]

CFI shows the RE set for the control channel (PDCCH)
...
The CFI coded data is described in the following table:
CFI

CFI codeword < b0, b1, …, b31 >

HEX

1
2
3
4 (Reserved)

0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1 6db6db6d
1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0 B6db6db6
1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1 Db6db6db
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0

Table 17
...

The following Base Station Analyzer settings may affect the measurement accuracy, thus some
consideration is recommended
...
Offset—may affect the overall measurement accuracy
• Cyclic Prefix—setting may affect the subframe and slot power accuracy
• # of CFI—may affect the Channel Summary measurement result
...
There are three
main applications:
• Path diversity – where one radiated path may be subject to fading loss and another may not
• Beam steering – controlling the phase relationship of the electrical signal radiated at the antennas to
physically steer transmitted energy
• Path difference – separating the transmission antennas, creating spatial separation
• Cyclic delay diversity – deliberately delaying the signal of both antennas to create an artificial multipath
...
MIMO techniques applied to LTE downlink signals

In Tx Diversity and spatial multiplexing, signals are transmitted from two or more antennas
...
The time alignment error in Tx Diversity and spatial multiplexing transmission is specified
as the delay between the signals from two antennas at the antenna ports
...

LTE assigns different positions of frequency and time of the reference signals (RS) transmitted from two
different antennas, which is the basis of measuring the time alignment between the two antennas
...
MIMO Time Alignment measurement

Base Station Analyzer

Application Note: LTE PHY Layer Measurement Guide

39

Unwanted Emission
For WCDMA, the unwanted emissions requirements as recommended in ITU-R SM
...
5 MHz away from the carrier center frequency
...
5 MHz value is
derived as 250% of the necessary bandwidth (5 MHz for WCDMA) as per ITU-R SM
...
The frequency
range within 250% of the necessary bandwidth around the carrier centre may be referred to as the Out Of
Band (OOB) domain
...

In LTE, the channel bandwidth can range from 1
...
A similar scaling by 250% of the channel
bandwidth would result in a large OOB domain for LTE: for the 20 MHz LTE channel bandwidth option, the
OOB domain would extend to a large frequency range of up to ±5 MHz around the carrier center frequency
...
The operating band plus 10 MHz on
each side are covered by the LTE operating band unwanted emissions
...

It is known that the following factors affect the unwanted emission characteristic of transmitters
...
Each subcarrier is mutually orthogonal for FFT
processing, but due to inherent non-linearity, generation of intermodulation distortions is unavoidable
...
Among the IMD signals, the 3rd IMD components are located near the transmission
band affecting the adjacent channel
...

• harmonics—most transmitters have band pass filters at the end of the transmitter chain to suppress
harmonics but due to filter limitations on the cut-off, some leakage signal is created
...


Occupied Bandwidth
The occupied bandwidth is the width of a frequency band such that, below the lower and above the upper
frequency limits, the mean power emitted are equal to a specified percentage (β/2) of the total mean
transmitted power
...
5%
...


Base Station Analyzer

Application Note: LTE PHY Layer Measurement Guide

40

Figure 30
...
1)

In the Occupied Bandwidth function, the following parameters are set as default values on the Base Station
Analyzer
...

The following settings may affect the measurement accuracy, thus some consideration must be taken
...
Offset—may affect the overall measurement accuracy
• RF In Loss—may affect the overall power measurement accuracy
...
The
requirements shall apply regardless of transmitter type (single carrier or multi-carrier)
...

ACLR requirements are classified by the multiplexing scheme and filter type applied to the symbol shaping
...
4, 3
...
2dB
Square (BWConfig) 44
...

Table 19
...
2 with 10MHz
channel bandwidth
...


Figure 31
...
2)

The parameters presented in the measurement screen are defined as follows:
• Power Reference—the power of the main carrier under test measured over the transmission bandwidth
(9 MHz)
• Freq Offset—the frequency difference between the center frequency and the neighboring channel
• dBc—the power difference between the power reference and the power of adjacent channel over the same
bandwidth (9 MHz)
• dBm—the absolute power of adjacent channel over the integral bandwidth
• Lower—the adjacent channels located at the left (lower) side of the center frequency
• Upper—the adjacent channels located at the right (upper) side of the center frequency
...

These two measurements verify the transmitter’s performance
...

• RBW—100 kHz
• Attenuation—Auto
...

• Freq
...


SEM
The Spectrum Emission Mask (SEM) measurement shows the operating band unwanted emissions
...

The requirement shall apply regardless of the transmitter’s type (single carrier or multicarrier)
...
329
...

According to ITU-R SM
...
The Base Station Analyzer adopts the SEM mask for 5, 10, 15 and 20 MHz downlink signals for
operating bands beyond 2 GHz and for Category A as a default
...

Frequency offset
Frequency offset of
Test requirement
RBW
of measurement filter
measure filter center
-3dB point, ∆f frequency, f_offset

0 MHz ≤ ∆f < 5 MHz

5 MHz ≤ ∆f < 10 MHz

10 MHz ≤ ∆f ≤ ∆fmax


0
...
05
5
...
05 MHz
10
...
5 dBm

100 kHz



100 kHz

-13 dBm

1 MHz

Table 20
...
While measuring SEM, the
resolution bandwidth (RBW) is set as 100 kHz
...
Since the
-3 dB point is equal on the RBW filter bandwidth, the start point of the frequency offset is 50 kHz (1/2 of
RBW filter bandwidth) apart from both ends of the channel bandwidth
...
Definition of SEM sections

The following figure shows the Base Station Analyzer SEM measurement result:

Figure 33
...
1)

Gap period due
to RBW change
5MHz

Base Station Analyzer

Application Note: LTE PHY Layer Measurement Guide

44

The SEM measurement parameters are defined as follows:
•
•
•
•
•

Power reference—the channel power of the transmitted signal
Start/Stop—the section of each SEM interval
Freq—the frequency of the highest peak in the section
Abs—the absolute power of the highest peak
Rel—the power difference between the channel power and the power of the highest peak measured with
100 kHz RBW
• Pass/Fail—the condition whether the measurement violates the mask
...

• RBW—100 kHz
• Attenuation—Auto
...

• Freq
...


Over-the-Air Analysis
Over-the-air measurements provide signal quality at a specific location of the network
...


ID Scanner
The ID Scanner measures the six most powerful LTE signals at the measurement location providing a good
indication of the signal overlap required for successful handovers
...
In addition, it performs a dominance measurement based on the power level of the
primary and secondary synchronization channels (P-SCH and S-SCH) as well as the relationship they have
with the entire LTE channel power
...
Over-the-Air ID Scanner

Datagram
The LTE datagram provides a power level activity of all the resource blocks contained in the LTE downlink
signal through time, providing an indication of LTE’s downlink data utilization at the measurement’s
location
...
Over-the-Air Datagram Measurement

Base Station Analyzer

Application Note: LTE PHY Layer Measurement Guide

46

Control Channels
The measurement of control channels over the air provides the signal strength and modulation quality of a
specified LTE base station at the measurement location
...


Figure 36
...
3GPP TS 36
...
3rd Generation Partnership Project; Technical Specification Group Radio Access
Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation
(Release 8)
...
3GPP TS 36
...
3rd Generation Partnership Project; Technical Specification Group Radio Access
Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio
Access Network (E-UTRAN); Overall description; Stage 2 (Release 8)
...
3GPP TS 36
...
3rd Generation Partnership Project; Technical Specification Group Radio Access
Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Base Station (BS) radio transmission and
reception (Release 8)
...
LTE for UMTS - OFDMA and SC-FDMA Based Radio Access By Harri Holma, Antti Toskal

Application Note: LTE PHY Layer Measurement Guide

Base Station Analyzer

48

Test & Measurement Regional Sales
NORTH AMERICA

LATIN AMERICA

ASIA PACIFIC

TEL: 1 866 228 3762
FAX: +1 301 353 9216

TEL: +1 954 688 5660
FAX: +1 954 345 4668

TEL: +852 2892 0990
FAX: +852 2892 0770

EMEA

TEL: +49 7121 86 2222
FAX: +49 7121 86 1222

WEBSITE: www
...
com/test

Product specifications and descriptions in this document subject to change without notice
...
AN
...
TM

---