ETSI TR 101 542 V1.2.1 (2013-07)

Satellite Earth Stations and Systems (SES); Comparison of candidate radio interfaces performances in MSS context

RTR/SES-00350

General Information

• Status: Published
• Publication Date: 01-Jul-2013
• Technical Committee: SES SCN - Satellite Communications and Navigation
• Current Stage: 12 - Completion
• Due Date: 16-Jul-2013
• Completion Date: 02-Jul-2013
• Mandate: M/496

Standards Content (Sample)

Technical Report
Satellite Earth Stations and Systems (SES);
Comparison of candidate radio interfaces performances
in MSS context
2 ETSI TR 101 542 V1.2.1 (2013-07)

Reference
RTR/SES-00350
Keywords
interface, mobile, radio, satellite
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ETSI
3 ETSI TR 101 542 V1.2.1 (2013-07)
Contents
Intellectual Property Rights . 5
Foreword . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Symbols and abbreviations . 7
3.1 Symbols . 7
3.2 Abbreviations . 8
4 Introduction . 9
5 Conventional evaluation results on candidate radio interfaces in MSS context . 10
5.1 WCDMA based radio interface . 10
5.2 OFDM based radio interface . 10
5.3 Preliminary comparison of OFDM and WCDMA in MSS context . 11
6 Mobile satellite system architecture and service scenario . 11
7 High level radio interface description . 12
7.1 Overview . 12
7.2 HSPA frame structure . 13
7.3 LTE/WiMAX frame structure . 14
8 Radio interface parameters for performance comparison. 17
8.1 HSPA parameters . 17
8.2 LTE/ WiMAX parameters . 19
9 Hypothesis for performance comparison. 20
9.1 Channel model . 20
9.2 TWTA model . 21
9.3 Simulation parameters . 22
10 Performance comparison results . 23
10.1 Link performance aspect . 23
10.2 User data rate aspect . 23
10.3 Non-linearity effect . 23
11 Conclusion . 24
Annex A: Detailed description of simulation . 25
A.1 Overview . 25
A.2 HSPA Simulator . 25
A.3 LTE/WiMAX simulator . 26
A.4 FEC, Interleaving and rate matching . 27
A.5 Subcarrier multiplexing . 28
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4 ETSI TR 101 542 V1.2.1 (2013-07)
Annex B: Detailed link-level results . 31
B.1 Overview . 31
B.2 Downlink performance comparison . 31
B.3 Uplink performance comparison . 35
History . 37

ETSI
5 ETSI TR 101 542 V1.2.1 (2013-07)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Satellite Earth Stations and Systems
(SES).
ETSI
6 ETSI TR 101 542 V1.2.1 (2013-07)
1 Scope
The present document aims to compare the link level performances of several radio interfaces (HSPA, LTE and mobile
WiMAX) in geostationary based mobile satellite systems operating in S band or L band.
The present document provides a high level description of the radio interfaces to be compared. It then identifies their
key characteristics and defines the propagation channel used for the comparison.
Link level performances are compared in terms of required signal to noise ratio ( ) for a given block error rate
E N
b o
(BLER) and data rate.
The present document concludes on the respective qualitative benefits and drawbacks of the considered radio interfaces.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] H. Holma and A. Toskala, "WCDMA for UMTS, Radio Access for Third Generation Mobile
Communications", 2nd Edition, John Wiley & Sons, Ltd., 2002.
[i.2] ETSI TS 125 201 (V3.4.0): "Universal Mobile Telecommunications System (UMTS); Physical
layer - general description (3GPP TS 25.201 version 3.4.0 Release 1999)".
[i.3] H. Holma and A. Toskala, "HSDPA/HSUPA for UMTS, High Speed Radio Access for Mobile
Communications", John Wiley & Sons, Ltd., 2006.
[i.4] ETSI TS 125 201 (V5.3.0): "Universal Mobile Telecommunications System (UMTS); Physical
layer - general description (3GPP TS 25.201 version 5.3.0 Release 5)".
[i.5] ETSI TS 125 201 (V6.2.0): "Universal Mobile Telecommunications System (UMTS); Physical
layer - general description (3GPP TS 25.201 version 6.2.0 Release 6)".
[i.6] ETSI TS 125 211 (V6.9.0): "Universal Mobile Telecommunications System (UMTS); Physical
channels and mapping of transport channels onto physical channels (FDD) (3GPP TS 25.211
version 6.9.0 Release 6)".
[i.7] ETSI TS 136 201 (V8.2.0): "LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Long
Term Evolution (LTE) physical layer; General description (3GPP TS 36.201 version 8.2.0
Release 8)".
ETSI
7 ETSI TR 101 542 V1.2.1 (2013-07)
[i.8] ETSI TS 136 211 (V8.5.0): "LTE; Evolved Universal Terrestrial Radio Access (E-UTRA);
Physical channels and modulation (3GPP TS 36.211 version 8.5.0 Release 8)".
[i.9] ETSI TS 136 212 (V8.5.0): "LTE; Evolved Universal Terrestrial Radio Access (E-UTRA);
Multiplexing and channel coding (3GPP TS 36.212 version 8.5.0 Release 8)".
[i.10] IEEE 802.16-2009: "IEEE Standard for Local and Metropolitan Area Networks - Part 16: Air
Interface for Broadband Wireless Access Systems".
[i.11] ETSI TR 102 443 (V1.1.1): "Satellite Earth Stations and Systems (SES); Satellite Component of
UMTS/IMT-2000; Evaluation of the OFDM as a Satellite Radio Interface".
[i.12] R. van Nee and R. Prasad, "OFDM for Wireless Multimedia Communications", Artech House,
2000.
[i.13] WiMAX Forum, "Mobile WiMAX - Part I: A Technical Overview and Performance Evaluation",
2006.
[i.14] WiMAX Forum, Mobile WiMAX - Part II: "A Comparative Analysis", 2006.
[i.15] S. Sesia, I. Toufik and M. Baker,"LTE, the UMTS Long Term Evolution: from Theory to
Practice", John Wiley and Sons, 2009.
[i.16] Void.
[i.17] C. Gessner, "UMTS Long Term Evolution (LTE) Technology Introduction", Application Note
1MA111, Rohde and Schwarz, www2.rohde-schwarz.com/file/1MA111-2E.pdf, Sep. 2008.
[i.18] M. Maqbool, M. Coupechoux and P. Godlewski, "Subcarrier permutation types in IEEE 802.16e",
www.telecom-paristech.fr/-data/files/docs/id-792-1208254315-271.pdf, Apr. 2008.
[i.19] ETSI TR 102 662 (V1.1.1): "Satellite Earth Stations and Systems (SES); Advanced satellite based
scenarios and architectures for beyond 3G systems", March 2010.
[i.20] 3GPP TR 25.896 (V6.0.0): "Feasibility Study for Enhanced Uplink for UTRA FDD".
[i.21] J. Laiho, A. Wacker and T. Novosad, "Radio Network Planning and Optimization for UMTS",
John Wiley & Sons, Ltd., 2002.
[i.22] ETSI TR 102 058: "Satellite Earth Stations and Systems (SES); Satellite Component of
UMTS/IMT-2000; Evaluation of the W-CDMA UTRA FDD as a Satellite Radio Interface".
[i.23] ETSI TS 136 104 (V8.2.0): "LTE; Technical Specification Group Radio Access Network; Evolved
Universal Terrestrial Radio Access (E-UTRA); Base Station (BS) radio transmission and reception
(3GPP TS 36.104 version 8.2.0 Release 8)".
3 Symbols and abbreviations
3.1 Symbols
For the purposes of the present document, the following symbols apply:
α Code orthogonality factor
Energy per bit to noise spectral density ratio
E N
b o
E I Energy per chip to same cell interference density ratio
c or
G Geometry factor, which is the same cell interference to other cell interference ratio I I
or oc
-inf Negative infinite
W R Processing gain, which is the chip rate/bit rate
T The useful OFDM symbol duration
B
ΔF Carrier spacing
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8 ETSI TR 101 542 V1.2.1 (2013-07)
3.2 Abbreviations
For the purpose of the present document, the following abbreviations apply:
3G/ 4G 3rd/ 4th Generation (mobile systems)
3GPP 3rd Generation Partnership Project
AMC Adaptive Modulation and Coding
AWGN Additive White Gaussian Noise
BER Bit Error Rate
BLER Block Error Rate
BPSK Binary Phase Shift Keying
CDMA Code Division Multiple Access
CGC Complementary Ground Components
CP Cyclic Prefix
CPICH Common Pilot Channel
CRC Cyclic Redundancy Check
CTC Convolutional Turbo Code (Duo-Binary Turbo)
DCH Dedicated Channel
DFT Discrete Fourier Transform
DL Downlink
DL+UL Downlink + Uplink
DPCCH Dedicated Physical Control Channel
DPDCH Dedicated Physical Data Channel
DS-CDMA Direct Sequence Code Division Multiple Access
E-DCH Enhanced DCH
E-DPCCH Enhanced DPCCH
E-DPDCH Enhanced DPDCH
E-UTRA Evolved Universal Terrestrial Radio Access
FDD Frequency Division Duplex
FEC Forward Error Control Coding
F Frequency band in the spectrum allocated to FSS
FSS
FFT Fast Fourier Transform
F Frequency band in the spectrum allocated to MSS
MSS
FSS Fixed Satellite Service
FUSC Full Usage of the Sub-channels
HARQ Hybrid Automatic Repeat Request
HD High-speed Downlink
HSDPA High Speed Downlink Packet Access
HS-DSCH High Speed Downlink Shared Channel
HSPA High Speed Packet Access
HS-PDSCH High Speed Physical Downlink Shared Channel
HS-SCCH High Speed Shared Control Channel
HSUPA High Speed Uplink Packet Access
IBO Input Back-Off
IEEE Institute of Electrical and Electronics Engineers
IFFT Inverse Fast Fourier Transform
IR Incremental Redundancy
LOS Line Of Sight
LTE Long Term Evolution (of 3GPP UMTS)
MAESTRO Mobile Applications and sErvices based on Satellite and Terrestrial inteRwOrking
MIMO Multiple Input Multiple Output
MSS Mobile Satellite Services
NFFT Number of FFT samples
NLOS Non Line of Sight
OBO Output Back-Off
OFDM Orthogonal Frequency Division Multiplexing
OFDMA Orthogonal Frequency Division Multiple Access
OVSF Orthogonal Variable Spreading Factor
PAPR Peak to Average Power Ratio
PCCC Parallel Concatenated Convolutional Code (Binary Turbo)
PDSCH Physical Downlink Shared Channel
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9 ETSI TR 101 542 V1.2.1 (2013-07)
PhyL Physical Layer
PRB Physical Resource Block
PUSC Partial Usage of Subcarriers
PUSCH Physical Uplink Shared Channel
QAM Quadrature Amplitude Modulation
QPSK Quadrature Phase Shift Keying
RB Resource Block
RNC Radio Network Control
RV Redundancy Version
SC-FDMA Single Carrier Frequency Division Multiple Access
SES Satellite Earth Stations and Systems
SF Spreading Factor
SSPA Solid State Power Amplifier
STBC Space Time Block Code
Tb Symbol Time (OFDM, without cyclic extension)
TDD Time Division Duplex
Tg Guard Time or CP duration
Ts Symbol Time (OFDM, with cyclic extension)
TTI Transmit Time Interval
TWTA Travelling Wave Tube Amplifier
UE User Equipment
UL Uplink
UMTS Universal Mobile Telecommunications System
UTRA Universal Terrestrial Radio Access
VRB Virtual Resource Block
WCDMA Wideband Code Division Multiple Access
WiMAX Worldwide interoperability for Microwave Access
4 Introduction
WCDMA [i.1] to [i.6] is the air-interface for the universal mobile telecommunications system (UMTS) which is a 3G
mobile standard specified by the 3GPP. It is based on direct sequence code division multiple access (DS-CDMA) due to
its robustness in wideband channels and support for asymmetric data rate applications. Release 4 WCDMA has been
enhanced to Release 5 and 6 versions for higher data rate applications. These enhancements, referred to as high speed
packet access (HSPA), incorporate advanced features such as higher order modulation, fast link adaption, HARQ and
spatial diversity. However, prominent candidates for 4G mobile communications include the 3GPP LTE standard [i.7]
to [i.9] and the IEEE mobile WiMAX standard [i.10], both of which are based on orthogonal frequency division
multiple access (OFDMA) air-interface, due to its robustness against frequency-selective fading and flexibility of
subcarrier allocations. LTE is specified as the long term evolution of UMTS while HSPA can be regarded as its short
term evolution.
It is observed that all the standards share similarities in the advanced features introduced in HSPA. However, there are
fundamental differences in the air-interfaces, frame structures and system/link parameters. Moreover, these standards
and their advanced features were specified for terrestrial communications and it would be useful to establish their
performance under realistic satellite links (which involve satellite wideband fading channels and power amplifier non-
linearity). Therefore, in this study, we compare the link-level performance of HSPA with that of LTE and mobile
WiMAX, over satellite links.
Figure 1 describes the evolution of the three baseline terrestrial technologies. For performance comparison in the
present document, HSPA Release 6, LTE Release 8 and mobile WiMAX Release 1.0 versions are used.
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10 ETSI TR 101 542 V1.2.1 (2013-07)

Figure 1: Evolution of HSPA, LTE and Mobile WiMAX
5 Conventional evaluation results on candidate radio
interfaces in MSS context
In this clause, we recall outcomes of prior feasibility studies on the use of WCDMA and OFDM based radio interface in
the context of mobile satellite systems.
5.1 WCDMA based radio interface
The feasibility study on WCDMA UTRA FDD as a satellite radio interface has been done in TR 102 058 [i.22]. Main
study results are summarized as:
• MSS systems using WCDMA can complement UMTS network with additional capacity.
• Allows technology synergy and interoperability with terrestrial UMTS network.
• Enables full frequency reuse in all beams and satellites.
• Allows to support broadcast/multicast services over large areas.
• Suitable to complement terrestrial UMTS network coverage and services in areas where:
- terrestrial systems have not been deployed for business attractiveness reasons; or
- terrestrial system requires coverage and/or capacity complement; or
- terrestrial system has suffered environmental damages (crisis conditions).
In the present document, we will only consider HSPA operation of WCDMA.
5.2 OFDM based radio interface
A feasibility study on the use of OFDM as a satellite radio interface has been carried out and reported in
TR 102 443 [i.11]. Main results are summarized as:
• It appears that, notwithstanding the large PAPR, it is possible to efficiently transmit OFDM signals through
non-linear satellite links with very small IBO and OBO values.
• This surprising result is the fruit of virtuous cross-fertilization between careful predistortion design and
powerful forward error correction coding application.
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11 ETSI TR 101 542 V1.2.1 (2013-07)
• In frequency flat correlated Rice fading channels and perfect channel estimation, OFDM produces small losses
with respect to the HSDPA interface due to only the guard-time insertion.
• The link budget study shows that proper service reception can be attained in satellite LOS conditions. In
satellite NLOS propagation conditions, proper service reception could not be achieved with this radio interface
when considering a handheld terminal, due to a negative link margin. Nevertheless, the use of CGCs can be a
viable solution to restore proper service reception in areas where satellite reception is critical.
In the present document, we will only consider LTE and Mobile WiMAX version of OFDM.
5.3 Preliminary comparison of OFDM and WCDMA in MSS
context
Some preliminary comparisons were carried out in TR 102 443 [i.11]:
• In multi-path channel conditions (satellite and CGC links), OFDM shows its robustness and, for the considered
channel profiles and with ideal channel estimation, OFDM outperforms the radio interfaces based on
WCDMA and HSPA. Notably, this is achieved considering the same spectrum occupancy specifications.
• Computing the corresponding link budgets for the HSPA case results in low margin for all those cases where
the required Rx C/N is higher than for the OFDM case and this is especially true in the NLOS case and when
CGCs are considered.
6 Mobile satellite system architecture and service
scenario
Physical layer performance comparison is achieved in mobile satellite system architecture as below.

FMSS or F F SS
CGC’s Feeder link
FFSS
FMSS
Feeder link
User link from
3GPP core
satellite
network
F MSS
User link from
CGC
Access Network
CGC
Gateway
UE (optional)
Figure 2: Mobile satellite system architecture
The system may provide either single satellite or multiple satellite constellations and each satellite may provide either
single or multi-spot beam coverage. A location area may be either a single spot beam or a group of spot beams for
roaming users.
UEs are connected to the network via one or several satellites which redirect the radio signal to/from gateways. The
system allows for either a centralized gateway or a group of geographically distributed gateways, depending on the
operators requirements. The gateway connects the signal to the access network, e.g. Node Bs and RNC.
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12 ETSI TR 101 542 V1.2.1 (2013-07)
In a satellite environment, signal transmission suffers from path blocking due to buildings, mountains, etc. In order to
ensure coverage continuity in highly shadowed areas, the system can be possibly completed with Complementary
Ground Components (CGCs) whose role is to repeat the signal from the satellite to terrestrial coverage in the MSS
frequency band and from terrestrial coverage to satellite. CGCs's feeder link is either in MSS or a Fixed Satellite
Service (FSS) band.
From the system point of view, satellite and CGCs have the same functionality, which is signal repetition.
When CGCs are deployed, UEs are subject to communicate with the network:
• via the satellite only (areas where CGCs are not deployed or situation with no signal view from CGCs);
• via CGCs only (situation where there is no view of the satellite signal);
• simultaneously via satellite and CGCs.
In this performance comparison, two application scenarios based on the 5 MHz bandwidth are investigated, which are
the outdoor rural and outdoor urban environment respectively, with a major difference being the use of repeaters in the
urban area to boost the weak satellite signal. A carrier frequency of 2,5 GHz (S-Band) has been used in modelling the
Doppler characteristics of the channel. It should be noted that higher-order modulation, AMC, HARQ, STBC/MIMO
and power control are not included in this link-level analysis due to the inefficiencies of these techniques in fast-fading
satellite links.
7 High level radio interface description
7.1 Overview
The 3GPP UMTS Release 4 standard is based on wideband code division multiple access (WCDMA) air-interface
wherein each user channel is defined by signal spreading with channelization codes or signatures. WCDMA is based on
QPSK modulation, 5 MHz carrier bandwidth and FDD duplexing and can support data rates up to 2 Mbps [i.1] and
[i.2]. However, it has been enhanced to support higher data rate services with better power/bandwidth efficiencies by
using advanced link-level techniques in the subsequent releases (Release 5 and Release 6) of the 3GPP UMTS standard.
These enhanced versions are known as the high speed packet access (HSPA) which consists of the high speed downlink
packet access (HSDPA) and the high speed uplink packet access (HSUPA) standards respectively [i.3] to [i.6].
The high speed-downlink shared channel (HS-DSCH) is introduced in HSDPA in order to support bursty, asymmetric
and high data rate packet applications in user terminals. It supports QPSK/16QAM modulations and uses a basic rate
1/3 parallel concatenated convolutional turbo code (PCCC), with rate-matching to higher or lower code rates via
puncturing or repetition. Furthermore, it incorporates important features such as fast link adaptation, HARQ, fixed
spreading factor, fast scheduling, multi-code transmission, short TTI of 2 ms, spatial diversity and efficient power
utilisation but does not support power control or soft handover. Similarly, an enhanced dedicated channel (E-DCH) is
introduced in HSUPA in order to support higher uplink data rates. It makes use of BPSK modulation, orthogonal
variable spreading factor (OVSF) codes and a TTI of 10 ms. However, the use of a shorter TTI of 2 ms is (optionally)
provided, for better utilization of the short term channel capacity. HSUPA also incorporates features such as link
adaptation, HARQ, multi-code transmission and MIMO. In general, it is noted that the more efficient scheduling
mechanism in HSPA allows better use of the available spectrum and power budget.
On the other hand, the LTE and WiMAX standards [i.7] to [i.11] are based on orthogonal frequency division
multiplexing (OFDM) air-interface [i.12], wherein each user resource is defined by time-frequency subcarrier
allocations. Both standards support scalable bandwidths (e.g. 1,25 MHz, 5 MHz and above), FDD/TDD duplexing and
are designed to provide high data rate services with improved power/bandwidth efficiencies. Similar to the HSPA
standards, they also incorporate advanced link-level techniques such as AMC, HARQ, short TTI, and MIMO. It should
be noted that LTE is a 3GPP standard which is structured as the long term evolution of UMTS while HSPA can be
considered as its short-term evolution. Similar to HSPA, the LTE standard uses a basic rate 1/3 parallel concatenated
convolutional turbo code (PCCC) with rate-matching whereas WiMAX specifies a variety of FEC codes, including the
duo-binary convolutional turbo code (CTC). The LTE and WiMAX standards share a lot of similarities due to their
common use of OFDMA. However, there are differences in frame structure, system parameters and subcarrier
multiplexing. Furthermore, LTE uses a DFT-spread OFDMA in its uplink in contrast to WiMAX which uses direct
OFDMA in both uplink and downlink.
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13 ETSI TR 101 542 V1.2.1 (2013-07)
7.2 HSPA frame structure
HSDPA has a 10 ms radio frame which is consistent with the Release 4 WCDMA standard, wherein each radio frame
consists of 15 slots and each slot is made up of 2 560 chips, resulting in a chip rate of 3,84 MChips/s. However, as
shown in figure 3, it uses a shorter TTI equivalent to one subframe of 2 ms duration (i.e. 3 slots) in contrast to the
longer TTIs (10 ms, 20 ms, etc.) supported in Release 4 WCDMA. This enables it to achieve fast link adaptation, fast
scheduling and low latency. HSDPA uses a fixed spreading factor of 16 and the number of coded bits per TTI is only
dependent on the modulation used. For QPSK, this is equal to 960 bits per channelization code while the number of
coded bits becomes doubled for 16-QAM as shown in table 1. The transport channel for HSDPA is the High Speed
Downlink Shared Channel (HS-DSCH) which is carried on the High Speed Physical Downlink Shared Channel
(HS-PDSCH). An HS-PDSCH corresponds to one channelization code and multi-code transmission is supported, which
translates to one user equipment (UE) being assigned multiple channelization codes in the same TTI, depending on its
capability. The High Speed Shared Control Channel (HS-SCCH) carries relevant downlink control information
associated with the HS-DSCH.
Table 1: HS-PDSCH slot formats [i.6]
Channel Bit Channel Symbol Bits/ HS-DSCH
Slot format #i SF Bits/ Slot Ndata
Rate (kbps) Rate (ksps) subframe
0(QPSK) 480 240 16 960 320 320
1(16QAM) 960 240 16 1 920 640 640

Data
N bits
data 1
k
T = 2560 chips, M*10*2 bits (k=4)
slot
Slot #0 Slot#1 Slot #2
1 subframe: T = 2 ms
f
Figure 3: HSDPA Frame Structure [i.6]

E-DPDCH
E-DPDCH
Data, N bits
data
k
T = 2560 chips, N = 10*2 bits (k=0…7)
slot data
E-DPCCH
10 bits
T = 2560 chips
slot
Slot #0 Slot #1 Slot #2 Slot #i Slot #14
1 subframe = 2 ms
1 radio frame, T = 10 ms
f
Figure 4: HSUPA Frame Structure [i.6]
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14 ETSI TR 101 542 V1.2.1 (2013-07)
HSUPA also has a radio frame structure similar to that of HSDPA and Release 4 WCDMA, wherein each radio frame
consists of 15 slots and each slot is made up of 2 560 chips as shown in figure 2. However, it uses a TTI of 10 ms
duration with an optional support for 2 ms [i.3] and [i.6]. HSUPA uses BPSK modulation and OVSF channelization
codes (with spreading factor ranging from 256 down to 2). Consequently, the number of coded bits per TTI varies with
the spreading factor as shown in table 2. The transport channel for HSUPA is the Enhanced Dedicated Channel
(E-DCH) which is carried on the Enhanced Dedicated Physical Data Channel (E-DPDCH). This channel co-exists with
the Release 99 DCH and there may be zero, one, or several E-DPDCH on each radio link. The Enhanced Dedicated
Physical Control Channel (E-DPCCH) is used to transmit control information associated with the E-DCH. There is only
one E-DPCCH on each radio link, transmitted simultaneously with the E-DPDCH and always accompanied by the
Release 99 DPCCH (which is used for channel estimation).
Table 2: E-DPDCH slot formats [i.6]
Channel Bit Rate Bits/ Bits/ Bits/Slot
Slot Format #i SF
(kbps) Frame Subframe N
data
0 15 256 150 30 10
1 30 128 300 60 20
2 60 64 600 120 40
3 120 32 1 200 240 80
4 240 16 2 400 480 160
5 480 8 4 800 960 320
6 960 4 9 600 1 920 640
7 1 920 2 19 200 3 840 1 280
7.3 LTE/WiMAX frame structure
In the LTE standard, the basic resource for either UL or DL transmission is a resource block (RB), which is defined as
12 tones x 6 OFDM symbols for the extended CP configuration and 12 tones x 7 OFDM symbols for the normal CP
configuration. The normal CP configuration is intended for environments with low multipath caracteristics. The
extended CP configuration is intended for environments with high multipath characteristics. Each RB includes both
pilot and data subcarriers.
Table 3 : Number of Resource Block for given Channel bandwidth
Channel bandwidth [Mhz] 1,4 3 5 10 15 20
Number of Resource Block per 0,5 ms slot 6 15 25 50 75 100
Number of Resource Block per 10 ms frame 120 300 500 1 000 1 500 2 000

A TTI in LTE consists of two adjacent resource blocks in time domain. The LTE TTI is equivalent to one subframe,
with duration of 1 ms (equivalent to two time slots) for both physical uplink and downlink shared channels (PUSCH
and PDSCH) and one radio frame in LTE has a duration of 10 ms similar to WCDMA and HSPA.

Figure 5: Frame structure type 1 (FDD)
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15 ETSI TR 101 542 V1.2.1 (2013-07)

Figure 6: LTE downlink Resource Block (extended CP); 0,5 ms duration – 180 Khz

Figure 7: LTE uplink Resource Block (extended CP); 0,5 ms duration – 180 Khz
WiMax supports TDD and FDD mode. The frame duration is variable (2/2,5/4/5/8/10/12,5/20 ms). The number of
subcarriers depends on the size of the FFT (128, 512, 1 024, 2 048). Figure 8 shows an example of TDD frame, with the
different burst in time and frequency.
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16 ETSI TR 101 542 V1.2.1 (2013-07)

Figure 8: WiMAX frame structure example (TDD)
Figure 9 shows an example of FDD frame. The frame is split in two groups, each terminal is affected to one of these
groups:
Figure 9: WiMAX frame structure example (FDD)
The basic resource in WiMAX is a subchannel of 48 data subcarriers.
There are two modes for the DL:
• FUSC (Fully Used Subcarriers): a subchannel is composed of 48 data subcarriers over one symbol time.
• PUSC (Partially Used Subcarriers): a subchannel is composed of 2 clusters over two symbol time. Each cluster
is composed of 12 data carriers and 2 pilot carriers.
In the UL there is only the PUSC mode: the subchannel is composed of six tiles. Each tile is composed of 4 carriers
over three symbol time. A tile contains 4 pilots and 8 data carriers.
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17 ETSI TR 101 542 V1.2.1 (2013-07)
Although a TTI is not explicitly specified in the present document, the WiMAX forum [i.13], [i.14] has configured a
radio frame structure of 5 ms duration for the TDD mode but has yet to specify one for the FDD mode. Therefore, in
keeping with the generic structure of the basic resource for both uplink and downlink, we envisage a TTI consisting of
6 OFDM symbols or its multiples. For the purpose of consistency with LTE, we choose a TTI of 12 OFDM symbols for
WiMAX FDD, which is equivalent to 6 clusters in downlink PUSC and 4 tiles in uplink PUSC, as shown in figures 5
and 6. This results in an WiMAX TTI duration of 1,37 ms for the 25 % CP configuration.
2 4 6 8 10 12
OFDM Symbols
NOTE: Blue: pilot subcarriers.
White: data subcarriers.
Figure 10: WiMAX downlink-PUSC TTI (6 clusters, 25 % CP); 1,37 ms duration

NOTE: Blue: pilot subcarriers.
White: data subcarriers.
Figure 11: WiMAX uplink-PUSC TTI (4 tiles, 25 % CP); 1,37 ms duration
8 Radio interface parameters for performance
comparison
8.1 HSPA parameters
The HSPA system design can be very complicated due to several factors that affect its link-level performance. This is as
a result of the fact that the whole bandwidth is accessed at all times by all users, wherein multiple access is achieved
through the use of channelization codes which spread each user's signal into chips using a unique signature. Therefore,
users are separated in the code domain and a uniform number of chips are transmitted per user. In HSPA, 38 400 chips
are transmitted in each 10 ms radio frame, 7 680 chips per 2 ms subframe and 2 560 chips per slot, resulting in a chip
rate of 3,84 Mchips/s. Table 4 shows important parameters that determine the link performance in HSPA.
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Subcarriers
18 ETSI TR 101 542 V1.2.1 (2013-07)
Table 4: HSPA system/link parameters
Info. Bits Total (Payload)
320 3 200 3 200 4 800 4 800
No. of Ch. Codes
1 10 10 15 15
Info. Bits / Ch. Code 320 320 320 320 320
FEC Rate 0,333 0,333 0,333 0,333 0,333
FEC Coded Bits / Ch. Code 960 960 960 960 960
FEC Coded Bits Total 960 9 600 9 600 14 400 14 400
Modulation Index 2 2 2 2 2
TTI Duration, [s]
0,002 0,002 0,002 0,002 0,002
No. of Chips / TTI
7 680 7 680 7 680 7 680 7 680
Spreading Factor 16 16 16 16 16
Max. Tx. Symbols / TTI 480 480 480 480 480
Chip Rate, [Chips/s] 3 840 000 3 840 000 3 840 000 3 840 000 3 840 000
Data Rate / Ch. Code, [Bits/s] 160 000 160 000 160 000 160 000 160 000
Data Rate Total, [Bits/s] 160 000 1 600 000 1 600 000 2 400 000 2 400 000
Processing Gain
24 2,4 2,4 1,6 1,6
Orthogonality Factor
1 1 0,5 1 0,5
Ec/Ior, [dB] -1 -1 -1 -1 -1
Ior/Ioc, [dB] 0 10 20 10 20
Eb/N0, [dB] 12,80 12,80 5,73 11,04 3,.97
Load Factor 0,44 0,09 0,31 0,09 0,31
Noise Rise, [dB] 2,54 0,40 1,62 0,40 1,62

In HSPA, the value is determined by parameters such as the processing gain, , geometry factor and
E N E I
b 0 c or
code orthogonality factor, as shown as below [i.3]. WCDMA uses orthogonal codes in the downlink to separate
simultaneously transmitted user signals. However, delay spread in a wideband channel causes the mobile receiver to see
part of the transmitted signal as multiple access interference. Consequently, the code orthogonality factor has a value of
1 for a single-tap downlink channel, whereas it varies between 0,4 and 0,9 for a wideband downlink channel [i.3].
E ()W R()E I
b c or
=
N ()1−α +()1 G
o
where,
: Energy-per-bit to noise-interference-density
E N
b 0
W R : Processing gain, which is the chip rate/bit rate
E I :    Energy-per-chip to same-cell-interference-density
c or
α :  Code orthogonality factor
G :           Geometry factor, which is the same-cell-interference to other cells-interference
ratio I I .
or oc
Table 1 shows that multi-code transmission increases the data rate while reducing the processing gain and achievable
E N . Also, increasing E I and/or G has a positive effect on the achievable E N . However, the effect of
b 0 c or b 0
a good geometry factor is dampened by loss of orthogonality in the multipath downlink channel as it results in a non-
linear increase in interference. Another factor to note is that the noise rise over thermal (which relates to the interference
margin in HSPA link budgets and is directly determined from the load factor) is most strongly affected by the geometry
factor as explained in [i.3].
It can be easily deduced from the discussions above that the capacity and coverage of the HSPA link is interference
limited. However, a frequency re-use of 1, interference control mechanisms and user demand for asymmetric data rates
provide great flexibilities in HSPA to achieve higher capacities, wherein compromise can be made between capacity
and coverage per user.
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19 ETSI TR 101 542 V1.2.1 (2013-07)
8.2 LTE/ WiMAX parameters
As discussed earlier, the LTE and WiMAX standards are based on OFDM/OFDMA multiplexing which is efficiently
implemented in digital receivers using the Fast Fourier Transform (FFT) algorithm. Both use fixed subcarrier spacing
for their OFDM signals and therefore support different FFT sizes for different bandwidths. In addition to the OFDM
signal design requirements, the subcarrier spacing in LTE was carefully chosen by the 3GPP as = 15 KHz, in order
ΔF
to ensure a signal sampling rate which is an integer multiple of the WCDMA chip rate [i.15]. Consequently, an FFT size
of 512 (corresponding to the 5 MHz bandwidth) results in an OFDM signal sampling rate of 7,68 MHz which is double
the WCDMA chip rate. Table 5 summarizes the OFDM parameters applicable to the extended CP configuration of LTE
and the 25 % CP configuration in WiMAX, wherein T is the useful OFDM symbol duration (T = 1 ΔF ), T is the
B G
B
guard interval or CP duration and T is total OFDM symbol duration.
S
Table 5: LTE/WiMAX OFDM parameters
Standard ∆F [KHz] T [μs] T [μs] T [μs] TTI [symbols] TTI [ms]
B G S
LTE extended 12 (including 2
CP
15 66,67 16,67 83,33 pilots in uplink) 1,00
5,21 (first) 71,88 (first) 14 (including 2
LTE normal CP 15 66,67 4,69 (other) 71,36 (other) pilots in uplink) 1,00
WiMAX 10,94 91,41 22,85 114,26 12 1,37

The time-frequency parameters shown in tables 6 and 7 for downlink and uplink configurations respectively show that
LTE is able to achieve higher data rates than WiMAX for a fixed bandwidth and the gap widens in the uplink. This is
due to the higher density of pilots used in the WiMAX standard in contrast to LTE. However a higher density of pilots
should enhance channel estimation accuracy, thereby compensating capacity loss with improved link performance.
Table 7 shows important parameters for OFDM link analysis, where it is shown that the achievable data rate is
dependent on the TTI data resource (i.e. excluding pilot tones), modulation, FEC code rate and TTI duration. In contrast
to HSPA, the energy-per-bit in OFDM is directly determined since users are multiplexed in the time-frequency domain
and not in the interference-limited code domain.
Table 6: 5 MHz DL time-frequency parameters
Basic Data TTI Data Max. QPSK Data Rate
Standard N N CP Length
FFT used
Resource Resource [Mbits/s]
LTE
extended
512 68 (sub carriers
CP 512 300 (see note 1) per RB) 3 400 6,80
160 (first) 80
(Note 1) (sub-carriers per
LTE
144 (rest) RB)
normal CP 512 300 (see note 1) (see note 2) 4 000 8,00
WiMAX
512 420 128 48 4 320 6,31
NOTE 1: For LTE, the CP duration is expressed as a multiple of a fixed sampling time Ts=1/(15000*2048). Thus
512 Ts = 16,67µs, 160 Ts = 5,2 µs, 144 Ts = 4,69 µs
NOTE 2: For LTE downlink, a Resource Block contains 6 OFDM data symbols (extended CP mode ) or 7 OFDM
data symbols (normal CP mode). Each of these OFDM data symbols is composed of 12 sub-carriers
which are modulated in QPSK mode (resp. BPSK, 16QAM, 64 QAM). In each Resource Block, 4 sub-
carriers are reserved for physical layer procedures. A TTI is one ms (2 slots)

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20 ETSI TR 101 542 V1.2.1 (2013-07)
Table 7: 5 MHz UL time-frequency parameters
Basic Data TTI Data Max. QPSK Raw Data Rate
Standard N N CP Length
FFT used
Resource Resource [Mbits/s]
LTE 60 (QPSK
extended 512 symbols per RB) 3 000 (QPSK
CP
512 300 (see note 1) (see note 2) symbols per TTI) 6,00
160 (first)
(see note 1) 72 (QPSK
LTE 144 (rest) symbols per RB) 3 600 (QPSK
normal CP
512 300 (see note 1) (see note 2) symbols per TTI) 7,20
WiMAX 512 408 128 48 3 264 4,76
NOTE 1: For LTE, the CP duration is e
...