This document provides an overview of topics covered in a two-day LTE training session, including: 1. An introduction to LTE radio procedures such as initial access, downlink physical channels, and cell search. 2. Details on synchronization signals like the primary and secondary synchronization signals that help devices find and synchronize to cells. 3. Descriptions of downlink reference signals and the system information broadcast channel that provide essential configuration details to devices.

1. Arief Hamdani Gunawan
1. Introduction to LTE 5. LTE Radio Procedures
2. OFDMA 6. LTE Uplink Physical Channels and
Signals
3. SC-FDMA
SC-
7. LTE Mobility
4. LTE Network and Protocol
8. LTE Test and Measurement

2. Day Two
Arief Hamdani Gunawan

3. Session 5: LTE Radio Procedures
•LTE Initial Access
•Downlink physical channels and signals
•Cell search in LTE
•Primary Synchronization Signal
•Secondary Synchronization Signal
•Cell search in LTE, reference signals
•Downlink Reference Signals
•Cell Search in LTE, essential system information
•System Information Broadcast in LTE
•Random Access Procedure
•How to derive information in LTE
•Hybrid ARQ in Downlink
•Default EPS Bearer Setup

4. LTE Initial Access

5. Downlink physical channels and signals

6. DL Physical Layer Procedures
• Cell search and synchronization
• Scheduling
– Dilakukan di base station (eNodeB)
– PDCCH (Phy DL Control Channel) menginformasikan alokasi time/freq resource
dan format transmisi yang digunakan kepada user.
– Scheduler mengevaluasi berbagai tipe informasi (parameter QoS, pengukuran
dari UE, kapabilitas UE, buffer status)
• Link Adaptation
– Skema modulasi dan coding untuk shared data channel diadaptasi sesuai
dengan kualitas link radio.
– Untuk tujuan ini, UE secara teratur melaporkan Channel Quality Indicator
(CQI) ke eNodeB.
• Hybrid ARQ (Automatic Repeat Request)
6

7. Cell Search in LTE

8. Synchronization & Cell Search
• UE yang ingin mengakses suatu sel LTE, terlebih dahulu harus melakukan
prosedur Cell Search.
• Cell Search terdiri dari serangkaian tahapan sinkronisasi, dimana UE
menentukan parameter waktu & frekuensi yang diperlukan untuk
mendemodulasi sinyal DL dan untuk mengirimkan sinyal UL dengan timing
yang tepat.
• Tiga kebutuhan sinkronisasi utama:
– Symbol timing acquisition
– Carrier frequency synchronization
– Sampling clock synchronization
8

9. Case Study
Cell Search for Multiple Bandwidths - Problem
• LTE offers system flexibility by supporting systems and UEs of multiple bandwidths.
• Challenge in synchronization & bandwidth detection.
• Unbalance traffic loads may result
9

10. Case Study
Cell Search for Multiple Bandwidths - Solution
Step 1:
Cell search using synchronization channel
detect center 1.25 spectrum
•The UE first detect the central
of entire 20-MHz spectrum
part of the spectrum regardless of
Step 2: the transmission bandwidth
BCH reception capability of the UE and that of the
cell site (BTS).
Step 3: •UE moves to the transmission
UE shifts to the center of carrier frequency assigned
bandwidth according to the UE
by the system and initiates data transmission
capability for actual
communication
Source: 3GPP R1-061651, “3GPP TR 25.814 v 1.5.0” 10

11. Synchronization Sequence
Dua prosedur cell search dalam LTE :
• INITIAL SYNCHRONIZATION
– UE mendeteksi suatu sel LTE dan mendekode semua informasi yang
diperlukan untuk registrasi.
– Diperlukan pada saat UE di-ON-kan atau ketika kehilangan koneksi dengan
serving cell.
• NEW CELL IDENTIFICATION
– Dilakukan ketika UE sudah terhubung ke suatu sel LTE dan sedang dalam
proses mendeteksi suatu sel tetangga baru.
– Dalam hal ini UE melaporkan hasil pengukuran yang terkait dengan sel baru ke
serving cell, sebagai persiapan untuk handover.
11

12. Cell Search procedure
RS : Reference Signal
PBCH : Physical Broadcast Channel
PSS : non-coherent detection
SSS : non-coherent/coherent detection
• PSS (Primary Synchronization Signal) dan SSS (Secondary Synchronization Signal) adalah kanal-kanal fisik
yang di-broadcast dalam setiap sel.
• Pendeteksian dua kanal ini :
– memungkinkan dilakukannya sinkronisasi waktu & frekwensi.
– memberikan identitas phy layer dari sel dan panjang cyclic prefix kepada UE.
– memberitahu UE apakah sel menggunakan FDD atau TDD.
12

13. Primary Synchronization Signal

14. Secondary Synchronization Signal

15. PSS and SSS frame and slot structure in FDD
15

16. PSS and SSS frame and slot structure in TDD
16

17. Cell search in LTE, reference signals

18. Downlink reference signals

19. Reference Signals & Channel Estimation
• Berbeda dengan jaringan berorientasi paket, LTE tidak menggunakan PHY Preamble untuk
memfasilitasi estimasi carrier offset, estimasi kanal, sinkronisasi waktu, dsb.
• Sebaliknya LTE menggunakan sinyal referensi khusus yang disisipkan dalam PRB.
• Sinyal referensi tsb dikirimkan selama simbol OFDM pertama dan kelima dari setiap slot
untuk short CP, dan simbol OFDM pertama dan ke-empat untuk long CP.
• Simbol-simbol referensi dikirimkan setiap selang 6 subcarrier.
• Dalam LTE downlink, terdapat 3 tipe RS :
– Cell-specific RS
– UE-specific RS
– MBSFN-specific RS
19

20. DL Reference Signal Structure for 2 & 4 Antenna Transmission
20

21. RS-aided Channel Estimation
• Problem estimasi kanal berhubungan dengan model kanal yang diasumsikan, yang
ditentukan oleh karakteristik propagasi fisik, termasuk jumlah antena Tx/Rx,
bandwidth transmisi, carrier frequency, konfigurasi sel dan kecepatan relatif antara
eNodeB dan UE.
• Kondisi propagasi mencirikan fungsi korelasi kanal dalam 3-dimensi, yaitu : domain
frekwensi, domain waktu dan domain ruang (spatial).
• Frequency-Domain Channel Estimation
– menggunakan Linear Interpolation Estimator
– menggunakan IFFT Estimator
• Time-Domain Channel Estimation
– menggunakan Finite & Infinite Length MMSE (Min Mean Squared Error)
– menggunakan Normalized Least-Mean-Square
• Spatial-Domain Channel Estimation
21

22. Cell search in LTE, essential system information

23. Downlink Physical Channels and Signals
P-SCH and S-SCH
Physical Downlink Shared Channel
Physical Downlink Control Channel
Physical Broadcast Channel
Physical Control Format Indicator Channel
Physical Multicast Channel
Physical Hybrid ARQ Indicator Channel
P-SCH : Primary Synchronization Channel
S-SCH : Secondary Synchronization Channel
23

24. LTE Downlink Physical Channels 1
24

25. LTE Downlink Physical Channels 2
25

26. System information broadcast in LTE

27. Random Access Procedure

28. How to derive information in LTE?

29. Indicating PDCCH format

30. Channel Coding & Link Adaptation
• Prinsip link adaptation menjadi landasan perancangan suatu interface radio yang
efisien untuk trafik data berbasis paket-switched.
• Link adaptation dalam LTE dilakukan dengan mengatur laju data informasi yang
dikirim (skema modulasi dan channel coding rate) secara dinamis, sesuai dengan
kualitas radio link.
• Link adaptation mempunyai hubungan yang sangat erat dengan perancangan
skema channel coding yang digunakan untuk FEC.
• Skema channel coding untuk FEC yang digunakan dalam LTE :
– Convolutional Coding
– Turbo Coding
– LDPC (Low Density Parity Check) coding
• Fitur advanced channel coding yang ditambahkan dalam LTE adalah : HARQ
(Hybrid Automatic Repeat Request).
30

31. Link Adaptation
• UE: Reports the finest possible
granularity
– The reporting scheme and
granularity depend on the radio
channel quality variation!
• ENB: Receives mobility and
quality information
– Incremental feedback
information forms a rough
picture of the radio channel with
the first report (s). The
granularity gets finer and finer
with each report.
31

32. Adaptive Modulation
• Adaptive Modulation & Coding
memastikan error rate tetap dibawah
limit yang dapat diterima, dengan
pengaturan modulasi dan coding rate
secara dinamis.
• Level modulasi yang lebih rendah
meningkatkan link budget dan fade
margin.
• Perubahan lingkungan propagasi
menyebabkan perubahan skema
modulasi dan coding.
• Dalam perencanaan kapasitas, variasi
kanal propagasi jangka-panjang harus
diperhitungkan.
32

33. Typical SNR Performance of LTE Modulation and Coding
33

34. Adaptive Modulation & Coding
34

35. QoS parameters for QCI

36. Hybrid ARQ in the downlink
• ACK/NACK for data packets transmitted in the downlink is the same as for HSDPA,
where the UE is able to request retransmission of incorrectly received data
packets,
– ACK/NACK is transmitted in UL, either on PUCCH (Physical Uplink Control Channel) or
multiplexed within PUSCH (Physical Uplink Shared Channel) see description of those UL
channels for details),
– ACK/NACK transmission refers to the data packet received four sub-frames (= 4 ms)
before,
– 8 HARQ processes can be used in parallel in downlink.

37. Hybrid ARQ Operation

38. Default EPS bearer setup

39. Session 6: Uplink Physical Channels and Signals
•Scheduling of UL Data
•UL Frequency Hopping
•Demodulation Reference Signal (DRS) in the UL
•Sounding Reference Signal (SRS) in the UL
•PUSCH power control & timing relation
•Acknowledging UL data packets on PHICH
•Physical UL Control Channel

40. Uplink physical channels and signals

41. Scheduling of uplink data

42. Uplink Physical Channels and Signals
Physical Random Access Channel
Physical Uplink Shared Channel
Physical Uplink Control Channel
• PUSCH (Physical Uplink Shared Channel): used for uplink shared data transmission.
• PUCCH (Physical Uplink Control Channel): used to carry ACK/NACK, CQI for downlink
transmission and scheduling request for uplink transmission. 42

43. Uplink Data Transmission
• Pada uplink, data dialokasikan dalam beberapa resource block (RB).
• Ukuran RB untuk uplink sama dengan yang digunakan untuk downlink,
tetapi untuk menyederhanakan disain DFT dalam pemrosesan sinyal
uplink, tidak semua kelipatan bulat digunakan (hanya kelipatan 2, 3 dan 5).
• Interval waktu transmisi uplink adalah 1 ms (sama dengan downlink).
• User data dibawa pada Physical Uplink Shared Channel (PUSCH), yang
ditentukan oleh BW transmisi dan pola frequency hoping.
• Physical Uplink Control Channel (PUCCH) membawa informasi kontrol
uplink, seperti : laporan CQI dan informasi ACK/NACK, yang terkait dengan
paket-paket data yang diterima pada arah downlink.
43

44. UL frequency hopping
Intra- and inter-subframe hopping,
• Intra-subframe hopping. UE hops to
another frequency allocation from
one slot to another within one
subframe,
• Inter-subframe hopping. Frequency
allocation changes from one subframe
to another one,
Two types of hopping,
• Type I. Explicit frequency offset is
used in the 2nd slot, can be
configured and is indicated to the UE
by resource block assignment /
hopping resource allocation field in
DCI format 0,
• Type II. Use of pre-defined hopping
pattern, allocated BW is divided into
sub-bands, hopping is done from one
sub-band to another from one slot or
subframe depending on configured
frequency hopping scheme.
Screenshots of R&S® SMU200A Vector Signal Generator

45. Demodulation Reference Signal (DRS) in the UL

46. Sounding Reference Signal (SRS) in the UL

47. PUSCH power control & timing relation

48. Random Access
• Suatu LTE UE (User Equipment) hanya dapat di-scheduled untuk transmisi
uplink, apabila uplink transmission timing-nya sinkron.
• Oleh karena itu LTE RACH (Random Access Channel) memainkan peran
penting sebagai interface antara non-synchronized UE dan skema
transmisi othogonal pada akses radio uplink LTE.
• Prosedur LTE random access mempunyai dua bentuk, yaitu : contention-
based atau contention-free.
• Dalam prosedur contention-based, suatu random access preamble
signature dipilih secara acak oleh UE, yang kemungkinan dapat
menyebabkan lebih dari satu UE mengirimkan signature yang sama secara
simultan.
• Dalam prosedur contention-free, eNodeB memiliki opsi untuk mencegah
terjadinya contention dengan mengalokasikan suatu dedicated signature
kepada UE.
48

49. Contention-based Random Access Procedure
Step 1 : Preamble transmission
Step 2 : Random Access
Response
Step 3 : L2/L3 message
Step 4 : Contention resolution
message
49

50. Contention-free Random Access Procedure
Prosedur contention-free
random access dapat
diterapkan dalam hal
diperlukan low latency, seperti
handover dan new downlink
data.
50

51. UL Transmission Procedures
• Uplink scheduling
– Dilakukan oleh base station (eNodeB)
– PDCCH (Phy DL Control Channel) menginformasikan alokasi time/freq resource
dan format transmisi yang digunakan kepada user.
– Scheduler mengevaluasi berbagai tipe informasi (parameter QoS, pengukuran
dari UE, kapabilitas UE, buffer status)
• Uplink Adaptation
– Untuk keperluan adaptasi uplink, dapat digunakan : transmission power
control, adaptive modulation & channel coding rate, serta adaptive
transmission BW.
• Uplink timing control
– Diperlukan untuk menyelaraskan waktu transmisi dari UE-UE yang berbeda,
dengan receiver window dari eNodeB.
• Hybrid ARQ
51

52. Acknowledging UL data packets on PHICH

53. Physical Uplink Control Channel
PUCCH carries Uplink Control Information (UCI), when no PUSCH is
available,
• If PUSCH is available, means resources have been allocated to the
UE for data transmission, UCI are multiplexed with user data,
UCI are Scheduling Requests (SR), ACK/NACK information related to DL
data packets, CQI, Pre-coding Matrix Information (PMI) and Rank
Indication (RI) for MIMO,
PUCCH is transmitted on reserved frequency regions, configured by
higher layers, which are located at the edge of the available
bandwidth
• Minimizing effects of a possible frequency-selective fading affecting
the radio channel,
• Inter-slot hopping is used on PUCCH,
• A RB can be configured to support a mix of PUCCH formats
(2/2a/2b and 1/1a/1b) or exclusively 2/2a/2b,

54. PUCCH
• CQI / PMI / RI are only signaled via PUCCH when periodic reporting is requested, scheduled
and a periodic reporting is only done via PUSCH

55. Physical Channel Procedure (1/2)

56. Physical Channel Procedure (2/2)

57. Test
Carries the DL-SCH and
PCH 1 A
Cell ID detection,
2
radio frame detection B
Operation BW, CP length,
MIMO config, cell ID, etc 3
C
SCH symbol timing
detection, frequency 4
offset detection D
RB assignment, transport
format, RSN#, HARQ
Proc#, TCP Command,
Cyclic shift for DMRS, UE
5 E
identification

58. Answer
SCH symbol timing detection,
frequency offset detection
Cell ID detection,
radio frame detection
Operation BW, CP length, MIMO
config, cell ID, etc
RB assignment, transport format,
RSN#, HARQ Proc#, TCP Command,
Cyclic shift for DMRS, UE
identification
Carries the DL-SCH and PCH

59. Session 7: LTE Mobility
•Handover (Intra-MME / Serving Gateway)
•LTE Interworking with 2G/3G: Two RRC States:
Connected and Idle
•LTE Interworking with CDMA2000 1xRTT and
HRPD
•MIMO
•LTE MIMO downlink modes
•LTE downlink transmitter chain
•Downlink transmitter diversity - Space Frequency
Block Coding (2 Tx antenna case)
•Downlink Spatial Multiplexing - codebook based
precoding
•LTE MIMO UL Schemes

60. Logical High Level Architecture for The Evolved System
GB
GERAN
GPRS Core Rx+
Iu SGSN
S4 Operator’s
UTRAN S6 S7 IP Services
(e.g. IMS, PSS,
S3 etc,)
IASA
MME 3GPP SAE S2b
eNB eNB UPE S5a anchor S5b anchor
S1 SGi
eNB eNB S2a WLAN 3GPP
Evolved RAN (LTE) EPC (SAE) EPDG
IP Access
Trusted non 3GPP WLAN
IP Access Access Network
• EPS uses the concept of EPS bearers to route IP traffic from a gateway in the PDN to the UE.
• A bearer is an IP packet flow with a defined Quality of Service (QoS) between the gateway and the
UE.
• The E-UTRAN and EPC together set up and release bearers as required by applications.

61. SAE Bearer Model

62. Overview of the evolved system architecture
User and bearer
information exchange for
inter 3GPP access system
mobility
C-Plane : S1-C between eNB and MME
U-Plane : S1-U between eNB and UPE
Transfer of subscription and
authentication data for user
MME : Mobility Management Entity access to the evolved system (AAA
UPE : User Plane Entity interface)
3GPP Anchor : Mobility anchor between 2G/3G and LTE access systems (based on GTP)
SAE Anchor : Mobility anchor between 3GPP access systems (2G/3G/LTE) and non-3GPP access systems (e.g. WLAN, WiMAX).

63. SAE Architecture – Functions per Element

64. SAE Architecture 3GPP2 Operator
detailed view, non-roaming case, 3GPP2 accesses

65. SAE Roaming support
extending today’s successful model

66. SAE impact on IMS
overview

67. Handover (Intra-MME/Serving Gateway)

68. LTE Interworking with 2G/3G
Two RRC states: CONNECTED & IDLE

69. LTE Interworking with CDMA2000 1xRTT
and HRPD (High Rate Packet Data)

70. Introduction to MIMO:
gains to exploit from multiple antenna usage
Transmit diversity (TxD)
• Combat fading
• Replicas of the same signal
sent on several Tx antennas
• Get a higher SNR at the Rx
Spatial multiplexing (SM)
• Different data streams sent
simultaneously on different
antennas
• Higher data rate
• No diversity gain
• Limitation due to path
correlation
Beamforming

71. Multiple Antenna Technique:
Four Basic Model
71

72. Multiple Antenna Technique
Two popular techniques in MIMO wireless systems:
Spatial Diversity: Increased SNR Spatial Multiplexing: Increased rate
• Receive and transmit diversity mitigates • Spatial multiplexing yields substantial
fading and improves link quality increase spectral efficiency
72

73. Spatial Diversity
Transmit Diversity
• Space-time Code (STC): Redundant data sent over time and space domains
(antennas).
• Receive SNR increase about linearity with diversity order Nr Nt
• Provide diversity gain to combat fading
• Optional in 802.16d (2x2 Alamouti STBC), used in 3G CDMA
73

74. Spatial Multiplexing
MIMO Multiplexing
• Data is not redundant – less diversity but less repetition
• Provides multiplexing gain to increase data-rate
• Low (no) diversity compared with STC
74

75. MIMO Operation
75

76. Diversity & MIMO
76

77. LTE MIMO: downlink modes
• Transmit diversity:
– Space Frequency Block Coding (SFBC)
– Increasing robustness of transmission
• Spatial multiplexing:
– Transmission of different data streams simultaneously over
multiple spatial layers
– Codebook based precoding
– Open loop mode for high mobile speeds possible
• Cyclic delay diversity (CDD):
– Addition of antenna specific cyclic shifts
– Results in additional multipath / increased frequency
diversity

78. LTE downlink transmitter chain

79. Downlink transmit diversity
Space-Frequency Block Coding (2 Tx antenna case)

80. Downlink spatial multiplexing
codebook based precoding

81. LTE MIMO: uplink schemes
• Uplink transmit antenna selection:
– 1 RF chain, 2 TX antennas at UE
side
– Closed loop selection of transmit
antenna
– eNodeB signals antenna selection
to UE
– Optional for UE to support
• Multi-user MIMO / collaborative
MIMO:
– Simultaneous transmission from 2
Ues on same time/frequency
resource
– Each UE with single transmit
antenna
– eNodeB selects UEs with close-to
orthogonal radio channels

82. Multi User Scheduling
• Scheduler (untuk transmisi unicast) secara dinamis mengontrol resource waktu
dan frekwensi mana yang akan dialokasikan kepada suatu user pada suatu waktu
tertentu.
• DL control signalling memberitahu UE, resource dan format transmisi seperti apa
yang sudah dialokasikan.
• Scheduler dapat secara dinamis memilih strategi multiplexing terbaik dari
beberapa metode yang ada, misalnya : localized atau distributed allocation.
• Scheduling berinteraksi erat dengan link adaptation dan HARQ.
• Pertimbangan scheduling antara lain didasarkan pada :
– minimum & maximum data rate
– daya yang tersedia untuk di-share
– Persyaratan target BER
– parameter QoS
– laporan CQI (Channel Quality Indicator)
– kapabilitas UE
82

83. Channel-Dependent Scheduling
• Shared channel transmission • Scheduling in time and frequency
• Select user and data rate on domain
instantaneous channel quality – Link adaptation in time domain
– Time-domain adaptation used only
already in HSPA
83

84. Packet-scheduling framework
• Packet scheduler adalah entitas
pengendali untuk seluruh proses
scheduling.
• Berkonsultasi dengan modul LA (Link
Adaptation) untuk memperoleh estimasi
data rate yang dapat disuport untuk user
tertentu dalam sel.
• LA dapat menggunakan frequency-
selective CQI feedback dari user, untuk
memastikan estimasi data rate yang sesuai
dengan target BLER tertentu.
• Modul Offset calculation dalam proses
link-adaptation dapat digunakan untuk
menstabilkan performansi BLER dalam
kondisi LA yang tidak pasti.
84

85. Session 8: LTE Test and Measurement
•LTE RF Testing aspects
•eNB Modulation quality measurements
•ACLR in DL (FDD)
•eNB Performance Requirements
•UE RF Testing Aspects
•Transmit Modulation
•Inband Emission
•IQ Component
•ACLR Measurement
•Receiver characteristics
•LTE Wireless device testing from R&D upto conformance
•Stages of LTE terminal testing
•LTE Terminal Interoperability testing
•Test Scenarios for LTE Terminal IOT
•LTE Conformance Testing
•LTE Terminal Certification
•LTE Field Trials

86. System architecture for 3GPP access networks

87. PCRF
• It is responsible for policy control decision-making, as
well as for controlling the flow-based charging
functionalities in the Policy Control Enforcement
Function (PCEF) which resides in the P-GW.
• The PCRF provides the QoS authorization (QoS class
identifier and bitrates) that decides how a certain
data flow will be treated in the PCEF and ensures
that this is in accordance with the user’s subscription
profile.

88. P-GW
• The P-GW is responsible for IP address allocation for the UE,
as well as QoS enforcement and flow-based charging
according to rules from the PCRF.
• The P-GW is responsible for the filtering of downlink user IP
packets into the different QoS based bearers. This is
performed based on Traffic Flow Templates (TFTs).
• The P-GW performs QoS enforcement for Guaranteed Bit Rate
(GBR) bearers.
• It also serves as the mobility anchor for inter-working with
non-3GPP technologies such as CDMA2000 and WiMAX
networks.

89. S-GW
• All user IP packets are transferred through the S-GW, which
serves as the local mobility anchor for the data bearers when
the UE moves between eNodeBs.
• It also retains the information about the bearers when the UE
is in idle state (known as ECM-IDLE) and temporarily buffers
downlink data while the MME initiates paging of the UE to re-
establish the bearers.
• In addition, the S-GW performs some administrative functions
in the visited network such as collecting information for
charging (e.g. the volume of data sent to or received from the
user), and legal interception.
• It also serves as the mobility anchor for inter-working with
other 3GPP technologies such as GPRS and UMTS.

90. MME
• The MME is the control node which processes the signaling
between the UE and the CN.
• The protocols running between the UE and the CN are known
as the Non-Access Stratum (NAS) protocols.
• The main functions supported by the MME are classified as:
– Functions related to bearer management. This includes the
establishment, maintenance and release of the bearers, and is
handled by the session management layer in the NAS protocol.
– Functions related to connection management. This includes the
establishment of the connection and security between the network
and UE, and is handled by the connection or mobility management
layer in the NAS protocol layer.

91. HSS
• Home Subscription Server (HSS) is the subscription data repository for all
permanent user data. It also records the location of the user in the level of visited
network control node, such as MME. It is a database server maintained centrally in
the home operator’s premises.
• The HSS stores the master copy of the subscriber profi le, which contains
information about the services that are applicable to the user, including
information about the allowed PDN connections, and whether roaming to a
particular visited network is allowed or not. For supporting mobility between non-
3GPP ANs, the HSS also stores the Identities of those P-GWs that are in use. The
permanent key, which is used to calculate the authentication vectors that are sent
to a visited network for user authentication and deriving subsequent keys for
encryption and integrity protection, is stored in the Authentication Center (AuC),
which is typically part of the HSS.
• In all signaling related to these functions, the HSS interacts with the MME. The HSS
will need to be able to connect with every MME in the whole network, where its
UEs are allowed to move. For each UE, the HSS records will point to one serving
MME at a time, and as soon as a new MME reports that it is serving the UE, the
HSS will cancel the location from the previous MME.

92. EPS Connection Management
• To reduce the overhead in the E-UTRAN and processing in the UE, all UE-
related information in the access network can be released during long
periods of data inactivity.
• This state is called EPS Connection Management IDLE (ECM-IDLE). The
MME retains the UE context and the information about the established
bearers during these idle periods.
• To allow the network to contact an ECM-IDLE UE, the UE updates the
network as to its new location whenever it moves out of its current
Tracking Area (TA); this procedure is called a ‘Tracking Area Update’. The
MME is responsible for keeping track of the user location while the UE is
in ECM-IDLE.
• When there is a need to deliver downlink data to an ECM-IDLE UE, the
MME sends a paging message to all the eNodeBs in its current TA, and the
eNodeBs page the UE over the radio interface. On receipt of a paging
message, the UE performs a service request procedure which results in
moving the UE to ECM-CONNECTED state.

93. MME connections to other logical nodes
and main functions

94. S-GW connections to other logical nodes
and main functions

95. P-GW connections to other logical nodes
and main functions

96. PCRF connections to other logical nodes
and main functions
Each PCRF may be associated with one or more AF, P-GW and S-GW. There is only
one PCRF associated with each PDN connection that a single UE has.

97. LTE RF Testing Aspects
Base station (eNodeB) according to 3GPP
• Measurements are performed using • Rx characteristics (= Uplink):
Fixed Reference Channels (FRC) and Reference sensitivity level, Dynamic
EUTRA Test Models (E-TM), range, In-channel selectivity,
• Tx characteristic (= Downlink) Adjacent channel selectivity (ACS)
– Base station output power and narrow-band blocking, Blocking,
– Output power dynamics: RE Power Receiver spurious emissions, Receiver
Control dynamic range, total power intermodulation
dynamic range, • Performance requirements,
– Transmit ON/OFF power: Transmitter – …for PUSCH: Fading conditions, UL
OFF power, transmitter transient timing adjustment, high speed train,
period, HARQ-ACK multiplexed in PUSCH,
– Transmitted signal quality: Frequency – …for PUCCH: DTX to ACK performance,
Error, Error Vector Magnitude (EVM), ACK missed detection PUCCH format 1a
Time alignment between transmitter (single user), CQI missed detection for
antennas, DL RS power, etc. … PUCCH format 2, ACK missed detection
– Unwanted emissions: Occupied PUCCH format 1a (multiple user)
Bandwidth, Adjacent Channel Leakage – PRACH performance: FALSE detection
Power Ratio (ACLR), Operating band probability, detection requirements
unwanted emissions, etc. …
– Transmitter spurious emissions and
intermodulation,
3GPP TS 36.104: Base Station (BS) radio transmission and reception

98. eNB modulation quality measurements
• Frequency error
– If frequency error is larger than a few subcarrier, demodulation at the UE
might not work properly and cause network interference,
– Quick test: OBW, Limit for frequency error after demodulation 0.05 ppm + 12
Hz (1ms),
• Error Vector Magnitude (EVM),
– Amount of distortion effecting the receiver to demodulate the signal properly,
– Limit changes for modulation schemes QPSK (17.5%), 16QAM (12.5%), 64QAM
(8%),
• Time alignment,
– Only TX test defined for multiple antennas, measurement is to measure the
time delay between the signals for the two transmitting antennas, delay shall
not exceed 65 ns,
• DL RS power
– “Comparable” to WCDMA measurement CPICH RSCP; absolute DL RS power is
indicated on SIB Type 2, measured DL RS power shall be in the range of ±2.1
dB,

99. ACLR in DL (FDD)

100. ACLR in DL (FDD):
No filter definition in LTE!

101. eNB performance requirements
PRACH and preamble testing I
• PRACH testing is one of the performance requirements
defined in 3GPP TS 36.141 E-UTRA BS conformance testing,
– Total probability of FALSE detection of preamble (Pfa 0.1% or less),
– Probability of detection of preamble (Pd = 99% at defined SNR),
– Two modes of testing: normal and high-speed mode,
• Different SNR and fading profiles are used (table shows settings for
normal mode),

102. eNB performance requirements
PRACH and preamble testing I
– Depending on the mode different preambles are used to check
detection probability (table shows preamble to be used for normal
mode),

103. eNB performance requirements
PRACH and preamble testing II
• According to 3GPP TS 36.211 the NCS
value is not set directly instead it is
translated to a NCS configuration
value,
• This value is set in the signal
generator R&S® SMx or R&S® AMU,
Screenshot taken
from R&S®
SMU200A Vector
Signal Generator

104. UE RF testing

105. LTE RF Testing Aspects
User Equipment (UE) according to 3GPP
Tx characteristic Rx characteristics
• Transmit power, • Reference sensitivity level,
• Output power dynamics, • UE maximum input level,
• Transmit Signal Quality, • Adjacent channel selectivity,
– Frequency error, EVM vs. • Blocking characteristics,
subcarrier, EVM vs. symbol, LO
leakage, IQ imbalance, Inband • Intermodulation characteristics,
emission, spectrum flatness, • Spurious emissions,
• Output RF spectrum emissions, Performance requirements
– Occupied bandwidth, Spectrum • Demodulation FDD PDSCH (FRC),
Emission Mask (SEM), Adjacent
Channel Leakage Power Ratio • Demodulation FDD
(ACLR), PCFICH/PDCCH (FRC)
• Spurious Emission,
• Transmit Intermodulation,
3GPP TS 36.101: User Equipment (UE) radio transmission and reception

106. Transmit modulation
According to 3GPP specification LO leakage (or IQ origin offset) is removed from evaluated
signal before calculating EVM and in-band emission.

107. In-band emission

108. IQ component
• Also known is LO leakage, IQ offset, etc.,
• Measure of carrier feedthrough present in the signal,
• Removed from measured waveform, before calculating EVM and in-band emission
(3GPP TS 36.101 V8.3.0, Annex F),
• In difference to DL the DC subcarrier in UL is used for transmission, but subcarriers
are shifted half of subcarrier spacing (= 7.5 kHz) to be symmetric around DC
carrier,
• Due to this frequency shift energy of the LO falls into the two central subcarrier

109. ACLR measurement I

110. Receiver characteristics
• Throughput shall be >95% for…
– Reference Sensitivity Level,
– Adjacent Channel Selectivity,
– Blocking Characteristics,
• …using the well-defined DL reference
channels according to 3GPP specification

111. LTE wireless device testing
from R&D up to conformance

112. Stages of LTE terminal testing

113. LTE terminal interoperability testing
motivation
• Interoperability testing is used to
verify
– Connectivity of the UE with the
real network (by means of base
station simulators)
– Service quality, end-to-end
performance
– Different LTE features and
parametrizations
– Interworking between LTE and
legacy technologies
• The complete UE protocol stack
is tested.
• IOT test scenarios are based on
requirements from real network
operation and typical use cases.

114. LTE terminal interoperability testing
example test scenarios
• Registration
• UE initiated detach
• Network initiated detach
• Mobile originated EPS bearer establishment
• Mobile terminated EPS bearer establishment
• Cell (re-)selection
• GUTI reallocation
• Tracking are update
• …
• Plus: end-to-end scenarios (video streaming, VoIP, …)
• Plus: intra-LTE mobility, inter-RAT mobility

115. Test scenarios for LTE terminal IOT
different sources for maximum test coverage

116. LTE conformance testing
motivation
• Verifying compliance of terminals
to 3GPP LTE standard
– by validated test cases
implemented on registered test
platforms
– in order to ensure worldwide
interoperability of the terminal
within every mobile network
• 3GPP RAN5 defines conformance
test specifications for
– RF
– Radio Resource Management
(RRM)
– Signaling
• Certification organizations (e.g.
GCF) define certification criteria
based on RAN5 test specifications

117. LTE field trial testing and
coverage measurements

118. LTE field trials
requirements from different deployment scenarios
• Bandwidths from 1.4 MHz to 20 MHz
• Different LTE FDD and TDD frequency bands
• Combination with legacy technologies
(GSM/EDGE, WCDMA/HSPA, CDMA2000 1xEV-
DO)
• Spectrum clearance and refarming scenarios
• Femto cell / Home eNB scenarios

119. LTE field trials
scope of test tools
• Field trials provide input for:
– Calibration and verification of
planning tools for different
deployment scenarios
– Network optimization (capacity
and quality)
– Quality of service verification
– Definition of Key Performance
Indicators (KPIs) and
verification, also from
subscriber’s point of view
• Parallel use of scanners /
measurement receivers for
comparison with UE and base
station behaviour
• Support of IOT activities

120. Example result from the field
scanner measurements for LTE

121. 10 Steps to Determine 3G/4G
IP Data Throughput
1. Will my device connect? 6. What happens if I try real
2. Do I have a good quality application?
transmitter? 7. What happens under non-
3. Do I have a good quality ideal conditions?
receiver? 8. Is it robust?
4. Can I achieve max E2E 9. Does it work closed loop?
tput under ideal 10. How good is my battery
conditions with UDP life?
5. What about with TCP and
simultaneous UL/DL?

122. Step 1: Will my device connect?

123. Step 1: Will my device connect?
• Is the UE able to sync to the DL?
•Can I get through the connection set-up
• Can I ping my UE?
• If not take a log and de-bug message exchange
•Make edits as required with Message editor

124. 2. Do I have a good quality Transmitter?
RF test
• High data throughput testing relies on good quality UL
transmissions
• Look for the following:
– Ensure you have appropriate
power and attenuation
settings
– High EVM for high order
modulation schemes
– High EVM at the band edge
– Spurs both in band and out of
band
– Linearity issues/ spectral
growth
– Switching transients, LO
settling time
– Repeat tests with any “other”
radio’s active

125. 3GPP Tx Measurements

126. UL RF Measurements

127. 3. Do I have a good quality receiver?
• High Data throughput
testing relies on good a
quality receiver
• Look for the following:
– sensitivity for different
modulation schemes
– Max input level
performance
– susceptibility to
interference (simultaneous
UL/DL, other radios, spurs
from digital board, …)

128. 3. Do I have a good quality receiver?

129. DL Data Throughput for TD LTE
(20MHz channel, 2x2 MIMO, UL/DL config 5, special subframe config 6)

130. Measurement Technique: UDP vs FTP (TCP)
UDP FTP
+ Unacknowledged + Simulates real-world file
+ removes flow control transfers
complexity +Transferred files can be viewed
+ removes higher layer acks and/or compared
+ Less susceptible latency
- Adds flow control complexity
- Not the full story for file - Add higher layer acks and
transfers retransmissions
- Not suitable for used in shared - TCP Control algorithms sensitive
networks to multiple parameters
- Test system configuration can
affect results

131. 5. Can I achieve max E2E tput under ideal conditions
with TCP?
• TCP adds higher layer support for error detection, re-transmissions,
congestion control and flow control
• TCP flow control algorithms interpret “lost” packets as congestion
• Careful consideration of parameters such as window size, number
of parallel process, segment size etc. need to be considered

132. TCP “Flapping”

133. 6. What happens if I try a real application? …
(Voice, video, ftp …)

134. 7. What happens under non-ideal conditions?
•Typically fade the DL and use robust
UL
•Perform test mode and E2E testing
•Measure MAC (BLER & Tput) and IP
layer throughput
•Use TCP with care!

135. 8. Is it robust? …
• E2E IP tests PHY, MAC, PDCP, and IP layers all working
together at full rate
• Check processor can handle multiple real time activities – add
SMS and voice calls during E2E IP
• Check there are no memory overflow/leakage issues

136. 9. Does it work closed loop?
•BLER/Tput Testing
•Supports Test Mode and E2E Testing

137. 10. How good is my battery life?

138. Case Study
Automated Measurements Give Repeatable 21Mbps Results!

139. Case Study
Device Performance: MIPS Matter!

140. Case Study
Cat14 (21Mbps) Devices – Better the second time around

141. Case Study
Not All HSDPA Cat 6 Devices Have the Same Throughput

142. Final Note

143. The End
Thank You