This book provides an insight into the key practical aspectsand best practice of 4G-LTE network design, performance, anddeployment Design, Deployment and Performance of 4G-LTENetworks addresses the key practical aspects and bestpractice of 4G networks design, performance, and deployment. Inaddition, the book focuses on the end-to-end aspects of the LTEnetwork architecture and different deployment scenarios ofcommercial LTE networks. It describes the air interface of LTEfocusing on the access stratum protocol layers: PDCP, RLC, MAC, andPhysical Layer. The air interface described in this book covers theconcepts of LTE frame structure, downlink and uplink scheduling,and detailed illustrations of the data flow across the protocollayers. It describes the details of the optimization processincluding performance measurements and troubleshooting mechanismsin addition to demonstrating common issues and case studies basedon actual field results. The book provides detailed performanceanalysis of key features/enhancements such as C-DRX for Smartphonesbattery saving, CSFB solution to support voice calls with LTE, andMIMO techniques. The book presents analysis of LTE coverage and link budgetsalongside a detailed comparative analysis with HSPA+. Practicallink budget examples are provided for data and VoLTE scenarios.Furthermore, the reader is provided with a detailed explanation ofcapacity dimensioning of the LTE systems. The LTE capacity analysisin this book is presented in a comparative manner with reference tothe HSPA+ network to benchmark the LTE network capacity. The bookdescribes the voice options for LTE including VoIP protocol stack,IMS Single Radio Voice Call Continuity (SRVCC). In addition, keyVoLTE features are presented: Semi-persistent scheduling (SPS), TTIbundling, Quality of Service (QoS), VoIP with C-DRX, Robust HeaderCompression (RoHC), and VoLTE Vocoders and De-Jitter buffer. Thebook describes several LTE and LTE-A advanced features in theevolution from Release 8 to 10 including SON, eICIC, CA, CoMP,HetNet, Enhanced MIMO, Relays, and LBS. This book can be used as a reference for best practices in LTEnetworks design and deployment, performance analysis, and evolutionstrategy. * Conveys the theoretical background of 4G-LTE networks * Presents key aspects and best practice of 4G-LTE networksdesign and deployment * Includes a realistic roadmap for evolution of deployed 3G/4Gnetworks * Addresses the practical aspects for designing and deployingcommercial LTE networks. * Analyzes LTE coverage and link budgets, including a detailedcomparative analysis with HSPA+. * References the best practices in LTE networks design anddeployment, performance analysis, and evolution strategy * Covers infrastructure-sharing scenarios for CAPEX and OPEXsaving. * Provides key practical aspects for supporting voice servicesover LTE, Written for all 4G engineers/designers working in networksdesign for operators, network deployment engineers, R&Dengineers, telecom consulting firms, measurement/performance toolsfirms, deployment subcontractors, senior undergraduate students andgraduate students interested in understanding the practical aspectsof 4G-LTE networks as part of their classes, research, orprojects.
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Abbreviations and Acronyms
Chapter 1: LTE Network Architecture and Protocols
1.1 Evolution of 3GPP Standards
1.2 Radio Interface Techniques in 3GPP Systems
1.3 Radio Access Mode Operations
1.4 Spectrum Allocation in UMTS and LTE
1.5 LTE Network Architecture
1.6 EPS Interfaces
1.7 EPS Protocols and Planes
1.8 EPS Procedures Overview
Chapter 2: LTE Air Interface and Procedures
2.1 LTE Protocol Stack
2.2 SDU and PDU
2.3 LTE Radio Resource Control (RRC)
2.4 LTE Packet Data Convergence Protocol Layer (PDCP)
2.5 LTE Radio Link Control (RLC)
2.6 LTE Medium Access Control (MAC)
2.7 LTE Physical Layer (PHY)
2.8 Channel Mapping of Protocol Layers
2.9 LTE Air Interface
2.10 Data Flow Illustration Across the Protocol Layers
2.11 LTE Air Interface Procedures
Chapter 3: Analysis and Optimization of LTE System Performance
3.1 Deployment Optimization Processes
3.2 LTE Performance Analysis Based on Field Measurements
3.3 LTE Case Studies and Troubleshooting
3.4 LTE Inter-RAT Cell Reselection
3.5 Inter-RAT Cell Reselection Optimization Considerations
3.6 LTE to LTE Inter-Frequency Cell Reselection
3.7 LTE Inter-RAT and Inter-frequency Handover
Chapter 4: Performance Analysis and Optimization of LTE Key Features: C-DRX, CSFB, and MIMO
4.1 LTE Connected Mode Discontinuous Reception (C-DRX)
4.2 Circuit Switch Fallback (CSFB) for LTE Voice Calls
4.3 Multiple-Input, Multiple-Output (MIMO) Techniques
Chapter 5: Deployment Strategy of LTE Network
5.1 Summary and Objective
5.2 LTE Network Topology
5.4 IPSec Gateway (IPSec GW)
5.5 EPC Deployment and Evolution Strategy
5.6 Access Network Domain
5.7 Spectrum Options and Guard Band
5.8 LTE Business Case and Financial Analysis
5.9 Case Study: Inter-Operator Deployment Scenario
Chapter 6: Coverage and Capacity Planning of 4G Networks
6.1 Summary and Objectives
6.2 LTE Network Planning and Rollout Phases
6.3 LTE System Foundation
6.4 PCI and TA Planning
6.5 PRACH Planning
6.6 Coverage Planning
6.7 LTE Throughput and Capacity Analysis
6.8 Case Study: LTE FDD versus LTE TDD
Chapter 7: Voice Evolution in 4G Networks
7.1 Voice over IP Basics
7.2 Voice Options for LTE
7.3 IMS Single Radio Voice Call Continuity (SRVCC)
7.4 Key VoLTE Features
7.5 Deployment Considerations for VoLTE
Chapter 8: 4G Advanced Features and Roadmap Evolutions from LTE to LTE-A
8.1 Performance Comparison between LTE's UE Category 3 and 4
8.2 Carrier Aggregation
8.3 Enhanced MIMO
8.4 Heterogeneous Network (HetNet) and Small Cells
8.5 Inter-Cell Interference Coordination (ICIC)
8.6 Coordinated Multi-Point Transmission and Reception
8.7 Self-Organizing, Self-Optimizing Networks (SON)
8.8 LTE-A Relays and Home eNodeBs (HeNB)
8.9 UE Positioning and Location-Based Services in LTE
End User License Agreement
Table of Contents
Chapter 1: LTE Network Architecture and Protocols
Emirates Integrated Telecomms Co., UAE
Mohamed A. El-saidny
QUALCOMM Technologies, Inc., USA
Mahmoud R. Sherif
Emirates Integrated Telecomms Co., UAE
This edition first published 2014
© 2014 John Wiley & Sons, Ltd
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Library of Congress Cataloging-in-Publication Data
Design, deployment and performance of 4G-LTE networks : A Practical Approach / Dr Ayman Elnashar,
Mr Mohamed A. El-saidny, Dr Mahmoud Sherif.
Includes bibliographical references and index.
ISBN 978-1-118-68321-7 (hardback)
1. Wireless communication systems. 2. Mobile communication systems. I. Title.
A catalogue record for this book is available from the British Library.
To my beloved kids Noursin, Amira, and Yousef. You're the inspiration!
This book is dedicated to the memory of my father (God bless his soul) and also my mother, who's been a rock of stability throughout my life. This book is also dedicated to my beloved wife whose consistent support and patience sustain me still.
My sincerest appreciations for a lifetime career that has surpassed anything my imagination could have conceived.
To my Family for all their continuous support. To my elder brother for his guidance and motivation throughout the years. To my inspirational, intelligent, and beautiful daughter, Hana.
Your work is going to fill a large part of your life, and the only way to be truly satisfied is to do what you believe is great work. And the only way to do great work is to love what you do. If you haven't found it yet, keep looking. Don't settle. As with all matters of the heart, you'll know when you find it. – Steve Jobs
Mohamed A. El-saidny
This work would not have been possible without the consistent and full support of my beloved family. To my beloved wife, Meram, to my intelligent, motivating, and beautiful kids, Moustafa, Tasneem, and Omar. You are my inspiration.
To my Dad, my Mom (God bless her soul), my brother, and my entire family. Thank you for all your support and encouragement.
There is no elevator to success. You have to take the stairs. – Unknown Author
Those who think they have found this elevator will end up falling down the elevator shaft
Mahmoud R. Sherif
Ayman Elnashar was born in Egypt in 1972. He received the B.S. degree in electrical engineering from Alexandria University, Alexandria, Egypt, in 1995 and the M.Sc. and Ph.D. degrees in electrical communications engineering from Mansoura University, Mansoura, Egypt, in 1999 and 2005, respectively. He obtained his M.Sc. and Ph.D. degrees while working fulltime. He has more than 17 years of experience in telecoms industry including GSM, GPRS/EDGE, UMTS/HSPA+/LTE, WiMax, WiFi, and transport/backhauling technologies. He was part of three major start-up telecom operators in MENA region (Mobinil/Egypt, Mobily/KSA, and du/UAE) and held key leadership positions. Currently, he is Sr. Director of Wireless Broadband, Terminals, and Performance with the Emirates Integrated Telecommunications Co. “du”, UAE. He is in charge of mobile and fixed wireless broadband networks. He is responsible for strategy and innovation, design and planning, performance and optimization, and rollout/implementation of mobile and wireless broadband networks. He is the founder of the Terminals department and also the terminals lab for end-to-end testing, validation, and benchmarking of mobile terminals. He managed and directed the evolution, evaluation, and introduction of du mobile broadband HSPA+/LTE networks. Prior to this, he was with Mobily, Saudi Arabia, from June 2005 to Jan 2008 and with Mobinil (orange), Egypt, from March 2000 to June 2005. He played key role in contributing to the success of the mobile broadband network of Mobily/KSA.
He managed several large-scale networks, and mega projects with more than 1.5 billion USD budgets including start-ups (LTE 1800 MHz, UMTS, HSPA+, and WiMAX16e), networks expansions (GSM, UMTS/HSPA+, WiFi, and transport/backhauling) and swap projects (GSM, UMTS, MW, and transport network) from major infrastructure vendors. He obtained his PhD degree in multiuser interference cancellation and smart antennas for cellular systems. He published 20+ papers in wireless communications arena in highly ranked journals such as IEEE Transactions on Antenna and Propagation, IEEE Transactions Vehicular technology, and IEEE Transactions Circuits and Systems I, IEEE Vehicular technology Magazine, IET Signal Processing, and international conferences. His research interests include practical performance analysis of cellular systems (CDMA-based & OFDM-based), 3G/4G mobile networks planning, design, and Optimization, digital signal processing for wireless communications, multiuser detection, smart antennas, MIMO, and robust adaptive detection and beamforming. He is currently working on LTE-Advanced and beyond including eICIC, HetNet, UL/DL CoMP, 3D Beamforming, Combined LTE/HSPA+, Combined LTE/WiFi: simultaneous reception, etc…
Mohamed A. El-saidny is a technical expert with 10+ years of international technical and leadership experience in wireless communication systems for mobile phones, modem chipsets, and networks operators. He received the B.Sc. degree in Computer Engineering and the M.Sc. degree in Electrical Engineering from the University of Alabama in Huntsville, USA in 2002 and 2004, respectively. From 2004 to 2008, he worked in Qualcomm CDMA Technology, Inc. (QCT), San Diego, California, USA. He was responsible for performance evaluation and analysis of the Qualcomm UMTS system and software solutions used in user equipment. As part of his assignments, he developed and implemented system studies to optimize the performance of various UMTS algorithms. The enhancements utilize Cell re-selection, Handover, Cell Search and Paging. He worked on several IOT and field trials to evaluate and improve the performance of 3G systems. Since 2008, he has been working in Qualcomm Corporate Engineering Services division in Dubai, UAE. He has been working on expanding the 3G/4G technologies footprints with operators, with an additional focus on user equipment and network performance as well as technical roadmaps related to the industry. Mohamed is currently supporting operators in Middle East and North Africa in addition to worldwide network operators and groups in LTE commercial efforts. His responsibilities are to ensure the device and network performance are within expectations. He led a key role in different first time features evaluations such as CSFB, C-DRX, IRAT, and load balance techniques in LTE. As part of this role, he is focused on aligning network operators to the device and chipset roadmaps and products in both 3G and 4G. Mohamed is the author of several international IEEE journal papers and contributions to 3GPP, and an inventor of numerous patents.
Mahmoud R. Sherif is a leading technical expert with more than 18 years of international experience in the design, development and implementation of fourth generation mobile broadband technologies and networks. He received his Ph.D. degree in Electrical Engineering from the City University of New York, USA in February 2000. His Ph.D. degree was preceded by the B.Sc. degree in Computer Engineering and the M.Sc. degree in Electrical Engineering from the University of Ain Shams in Cairo, Egypt in 1992, and 1996, respectively. From 1997 to 2008, he was working in the Wireless Business Unit at Lucent Technologies (which became Alcatel-Lucent in 2007), in Whippany, New Jersey, USA. He led the Voice and Data Quality and Performance Analysis team responsible for the end-to-end performance analysis of the different wireless/mobile technologies. In November 2008, he moved to Dubai in the United Arab Emirates to join the Emirates Integrated Telecommunications Co. “du” where he is now the Head of the Mobile Access Planning within du (Senior Director Mobile Access Planning) managing the Radio Planning, Site Acquisition and Capacity and Feature Management Departments. He is responsible for managing the planning of the mobile access network nationwide, Mobile Sites' Acquisition, Strategic Planning on Mobile Access Network Capacity Management, all Feature testing and rollout across 2G, 3G and LTE, defining and managing the financial resources efficiently and with alignment with company's financial targets (CAPEX & OPEX). He is also responsible for the mobile access network technology strategy in coordination with the commercial and marketing teams. He is considered a company expert resource in the various mobile broadband technologies, including HSPA+, LTE, VoLTE and LTE-A. He has published several related papers in various technical journals as well as multiple international conferences. He has multiple contributions to the 3GPP and other telecommunications standards. He also has multiple granted patents in the USA.
Cellular mobile networks have been evolving for many years. Several cellular systems and networks have been developed and deployed worldwide to provide the end user with quality and reliable communication over the air. Mobile technologies from the first to third generation have been quickly evolving to meet the need of services for voice, video, and data.
Today, the transition to smartphones has steered the user's interest toward a more mobile-based range of applications and services, increasing the demand for more network capacity and bandwidth. Meanwhile, this transition presents a significant revenue opportunity for network operators and service providers, as there is substantially higher average revenue per user (ARPU) from smartphone sales and relevant services. While the rollout of more advanced radio networks is proceeding rapidly, smartphone penetration is also increasing exponentially. Therefore, network operators need to ensure that the subscribers' experience stays the same as, or is even better than, with the older existing systems.
With the growing demand for data services, it is becoming increasingly challenging to meet the required data capacity and cell-edge spectrum efficiency. This adds more demand on the network operators, vendors and device providers to apply methods and features that stabilize the system's capacity and consequently improves the end-user experience. 4G systems and relevant advanced features have the capabilities to keep up with today's widespread use of mobile-communication devices, providing a range of mobile services and quality communications.
This book describes the long term evolution (LTE) technology for mobile systems; a transition from third to fourth generation. LTE has been developed in the 3GPP (Third Generation Partnership Project), starting from the first version in Release 8 and through to the continuing evolution to Release 10, the latest version of LTE, also known as LTE-Advanced. The analysis in this book is based on the LTE of 3GPP Release 8 together with Release 9 and Release 10 roadmaps, with a focus on the LTE-FDD (frequency division duplex) mode . Unlike other books, the authors have bridged the gap between theory and practice, thanks to hands on experience in the design, deployment, and performance of commercial 4G-LTE networks and terminals.
The book is a practical guide for 4G networks designers, planners, and optimizers, as well as other readers with different levels of expertise. The book brings extensive and broad practical hands-on experience to the readers. Practical scenarios and case studies are provided, including performance aspects, link budgets, end-to-end architecture, end-to-end QoS (quality of service) topology, dimensioning exercises, field measurement results, applicable business case studies, and roadmaps.
Chapters 1 and 2 describe the LTE system architecture, interfaces, and protocols. They also introduce the LTE air interface and layers, in addition to downlink and uplink channels and procedures.
Chapters 3 to 8 constitute the main part of the book. They provide a deeper insight into the LTE system features, performance, design aspects, deployment scenarios, planning exercises, VoLTE (voice over long term evolution) implementation, and the evolution and roadmap to LTE-Advanced. Further material supporting this book can be found in www.ltehetnet.com.
We would like to express our deep gratitude to our colleagues in Qualcomm and du for assisting in reviewing and providing excellent feedback on this work. We are indebted to Huawei team in the UAE for their great support and review of Chapters 5 and 6, and also for providing the necessary supporting materials. Special thanks go to the wireless broadband and terminals team at du for their valuable support. We acknowledge the support of Harri Holma from NSN, for reviewing and providing valuable comments on Chapters 5 and 6. We wish to express our appreciation to every reviewer who reviewed the book proposal and provided very positive feedback and insightful comments. Thanks for their valuable comments and suggestions. Our thanks go to our families for their patience, understanding, and constant encouragement, which provided the necessary enthusiasm to accomplish this book. Also, our deep and sincere appreciations go to our professors who supervised and guided us through our academic career. Finally, we would like to thank the publishing team at John Wiley & Sons for their competence, extensive support and encouragement throughout the project to bring this work to completion.
16-Quadrature amplitude modulation
64-Quadrature amplitude modulation
1G, 2G, 3G or 4G
1st, 2nd, 3rd, 4th generation
Third generation partnership project
Third generation partnership project 2
Authentication, authorization and accounting
Advanced encryption standard
Aggregate maximum bit rate
Adaptive modulation and coding
Acknowledged mode data
Access point name
Allocation and retention priority
Automatic repeat request
Broadcast control channel
Block error rate
Buffer status report
Common control channel
Control channel elements
Cyclic delay diversity
Code Division Multiplexed
Code division multiple access
Channel dependent scheduling
Control format indicator
Cost of Goods Sold
Channel quality indicator
Cyclic redundancy check
Charging Rules Function
Cell radio network temporary identifier
Closed subscriber group
Channel signal information
Distributed Antenna System
Dedicated control channel
Downlink control information
Discrete Fourier transform
Discrete Fourier transform spread orthogonal frequency division multiplexing
Downlink shared channel
Demodulation reference signal
Domain Name System
Dedicated traffic channel
Enhanced absolute granting channel
Earnings Before Interest, Taxes, Depreciation, and Amortization
Enhanced dedicated channel
Enhanced dedicated physical control channel
Enhanced dedicated physical data channel
Enhanced hybrid indicator channel
EPS encryption algorithm
EPS integrity algorithm
Equipment Identity register
EPS mobility management
Evolved node B
Evolved packet core
Energy per resource element
Evolved packet system
Enhanced relative granting channel
EPS session management
Encapsulated security protocol
Earthquake and tsunami warning system
Evolved UMTS terrestrial radio access; PHY aspects
Evolved UMTS terrestrial radio access network; MAC/L2/L3 aspects
Frequency division duplex
Frequency division multiplexing
Frequency division multiple access
Fast Fourier transform
First missing sequence
Frequency shift time diversity
Guaranteed bit rate
GSM/EDGE radio access network
GPRS gateway support node
General packet radio service
Global system for mobiles (European standard)
GPRS tunneling protocol – user
Globally unique MME identity
Globally unique temporary identifier
HARQ process ID
Hyper frame number
Hybrid ARQ indicator
High Level Design
Home location register
Home evolved node B identifier
Home public land mobile network
High rate packet data
High speed downlink packet access
High speed dedicated control channel
High speed packet access
High speed packet access evolved or enhanced
Home subscriber service
High speed uplink packet access
Inverse discrete Fourier transform
Internet Engineering Task Force
Inverse fast Fourier transform
IP Multimedia subsystem
International Mobile Subscriber Identity
IP connectivity access network
Idle signaling load reduction
Internal Rate of Return
L1, L2, L3
Layer 1, 2, 3
Location area code
Location area identifier
Location area updating
Logical channel group
Lightweight Directory Access
Localized frequency division multiplexing
Long term evolution
Linear time invariant
Medium access control
Message authentication code for integrity
Multimedia broadcast multicast service
Maximum bit rate
Multimedia broadcast over a single frequency network
Multicast control channel
Modulation and coding schemes
Multiple code word
Master information block
Mobility management entity
MME group ID
Mobile Subscriber Integrated Services Digital Network-Number
Mean Opinion Score
Multicast traffic channel
New data indicator
Net Present Value
Online Charging System
Offline Charging System
Orthogonal frequency division multiplexing
Orthogonal frequency division multiple access
Peak-to-average power ratio
Peak to average ratio
Physical broadcast channel
Policy charging and control
Paging control channel
Physical control format indicator channel
Policy and charging rules function
Physical downlink control channel
Packet data convergence protocol
Packet data gateway
Packet data network
Physical downlink shared channel
Packet data serving node
Protocol data unit
Packet error loss rate
Packet data network gateway
Physical hybrid automatic repeat request indicator channel
Power headroom report
Public land mobile network
Physical multicast channel
Precoding matrix indicator
Proxy mobile IP
Push-to-talk over cellular
Physical random access channel
Physical resource block
Primary synchronization code
Primary synchronization channel
Primary synchronization signal
Packet switched telephone network
Packet switched video telephony
Physical uplink control channel
Physical uplink shared channel
Quadrature amplitude modulation
QoS class identifier
Quality of service
Quadrature phase shift keying
Routing area code
Random access channel
Radio access network
Random access preamble identifier
Random access response
Routing area updating
Resource block group
RMS delay spread
Resource element group
Resource indication value
Radio link control
Radio link failure
Radio network controller
Radio network layer
Radio network temporary identifier
Robust header compression
Return On Investment
Radio resource control
Radio resource management
System architecture evolution
Single-carrier frequency division multiplexing
Single-carrier frequency division multiple access
Supplemental channel (CDMA2000)
Synchronization channel (WCDMA)
Stream control transmission protocol
Single code word
Service data low
Spatial division multiplexing
Spatial division multiple access
Service data unit
Space frequency block code
System frame number
Serving GPRS support node
System information message
System information block
Signal to interference noise ratio
Signal to noise ratio
Simple Object Access Protocol
Single Point of Failure
Sounding reference signals
Secondary synchronization code
Secondary synchronization channel
Secondary synchronization signal
Tracking area code
Tracking area identifier (_List)
Tracking area update
Time division duplex
Time division multiplexing
Time division multiple access
Traffic flow template
Transmit power control
Transmission time interval
Uplink control information
Uplink shared channel
Universal mobile telecommunications system
UMTS terrestrial radio access
UMTS terrestrial radio access network
Voice Activity Factor
Voice over Internet protocol
Voice over LTE
Virtual resource block
Weighted Average Cost of Capital
Wideband code division multiple access
Worldwide interoperability for microwave access
The interface between eNodeBs
Ayman Elnashar and Mohamed A. El-saidny
Cellular mobile networks have been evolving for many years. The initial networks are referred to as First Generation, or 1G systems. The 1G mobile system was designed to utilize analog. It included the AMPS (advanced mobile phone system). The Second Generation, 2G mobile systems, were introduced utilizing digital multiple access technology; TDMA (time division multiple access) and CDMA (code division multiple access). The main 2G networks were GSM (global system for mobile communications) and CDMA, also known as cdmaOne or IS-95 (Interim Standard 95). The GSM system still has worldwide support and is available for deployment on several frequency bands, such as 900, 1800, 850, and 1900 MHz. CDMA systems in 2G networks use a spread spectrum technique and utilize a mixture of codes and timing to identify cells and channels. In addition to being digital, as well as improving capacity and security, the 2G systems also offer enhanced services, such as SMS (short message service) and circuit switched (CS) data. Different variations of the 2G technology evolved later to extend the support of efficient packet data services, and to increase the data rates. GPRS (general packet radio system) and EDGE (enhanced data rates for global evolution) systems have been the evolution path of GSM. The theoretical data rate of 473.6 kbps enabled the operators to offer multimedia services efficiently. Since it does not comply with all the features of a 3G system, EDGE is usually categorized as 2.75G.
3G (Third Generation) systems are defined by IMT2000 (International Mobile Telecommunications). IMT2000 defines that a 3G system should provide higher transmission rates in the range of 2 Mbps for stationary use and 348 kbps in mobile conditions. The main 3G technologies are:
WCDMA (wideband code division multiple access)
—This was developed by the 3GPP (Third Generation Partnership Project). WCDMA is the air interface of the 3G UMTS (universal mobile telecommunications system). The UMTS system has been deployed based on the existing GSM communication core network (CN) but with a totally new radio access technology (RAT) in the form of WCDMA. Its radio access is based on FDD (frequency division duplex). Current deployments are mainly at 2.1 GHz bands. Deployments at lower frequencies are also possible, such as UMTS900. UMTS supports voice and multimedia services.
TD-CDMA (time division multiple access)
—This is typically referred to as UMTS TDD (time division duplex) and is part of the UMTS specifications. The system utilizes a combination of CDMA and TDMA to enable efficient allocation of resources.
TD-SCDMA (time division synchronous code division multiple access)
—This has links to the UMTS specifications and is often identified as UMTS-TDD low chip rate. Like TD-CDMA, it is also best suited to low mobility scenarios in microcells or picocells.
—This is a multi-carrier technology standard which uses CDMA. It is part of the 3GPP2 standardization body. CDMA2000 is a set of standards including CDMA2000 EV-DO (evolution-data optimized) which has various revisions. It is backward compatible with cdmaOne.
WiMAX (worldwide interoperability for microwave access)
—This is another wireless technology which satisfies IMT2000 3G requirements. The air interface is part of the IEEE (Institute of Electrical and Electronics Engineers) 802.16 standard which originally defined PTP (point-to-point) and PTM (point-to-multipoint) systems. This was later enhanced to provide greater mobility. WiMAX Forum is the organization formed to promote interoperability between vendors.
4G (Fourth Generation) cellular wireless systems have been introduced as the latest version of mobile technologies. 4G is defined to meet the requirements set by the ITU (International Telecommunication Union) as part of IMT Advanced.
The main drivers for the network architecture evolution in 4G systems are: all-IP (Internet protocol) -based, reduced network cost, reduced data latencies and signaling load, interworking mobility among other access networks in 3GPP and non-3GPP, always-on user experience with flexible quality of service (QoS) support, and worldwide roaming capability. 4G systems include different access technologies:
LTE and LTE-Advanced (long term evolution)
—This is part of 3GPP. LTE as it stands now does not meet all IMT Advanced features. However, LTE-Advanced is part of a later 3GPP release and has been designed specifically to meet 4G requirements.
—The IEEE and the WiMAX Forum have identified 802.16m as their offering for a 4G system.
UMB (ultra mobile broadband)
—This is identified as EV-DO Rev C. It is part of 3GPP2. Most vendors and network operators have decided to promote LTE instead.
The specifications of GSM, GPRS, EDGE, UMTS, and LTE have been developed in stages, known as 3GPP releases. Operators, network, and device vendors use these releases as part of their development roadmap. All 3GPP releases are backward compatible. This means that a device supporting one of the earlier releases of 3GPP technologies can still work on a newer release deployed in the network.
The availability of devices on a more advanced 3GPP release makes a great contribution to the choice of evolution by the operator. Collaboration between network operators, network vendors, and chipset providers is an important step in defining the roadmap and evolution of 3GPP features and releases. This has been the case in many markets.
3GPP Release 99 has introduced UMTS, as well as the EDGE enhancement to GPRS. UMTS contains all features needed to meet the IMT-2000 requirements as defined by the ITU. It is able to support CS voice and video services, as well as PS (packet switched) data services over common and dedicated channels. The theoretical data rate of UMTS in this release is 2 Mbps. The practical uplink and downlink data rates for UMTS in deployed networks have been 64, 128, and 384 kbps.
Release 4 includes enhancements to the CN. The concept of all-IP networks has been introduced in this release. There has not been any significant change added to the user equipment (UE) or air interface in this release.
Release 5 is the first major addition to the UMTS air interface. It adds HSDPA (high speed downlink packet access) to improve capacity and spectral efficiency. The goal of HSDPA in the 3GPP roadmap was to improve the end-user experience and to keep up with the evolution taking place in non-3GPP technologies. During the time when HSDPA was being developed, the increasing interest in mobile-based services demanded a significant improvement in the air interface of the UMTS system.
HSDPA improves the downlink speeds from 384 kbps to a maximum theoretical 14.4 Mbps. The typical rates in the Release 5 networks and devices are 3.6 and 7.2 Mbps. The uplink in Release 5 has preserved the capabilities of Release 99.
HSDPA provides the following main features which hold as the fundamentals of all subsequent 3GPP evolutions:
—In addition to the original UMTS modulation scheme, QPSK (quadrature phase shift keying), Release 5 also includes support for 16-QAM (quadrature amplitude modulation).
—Based on fast feedback from the mobile in the form of a CQI (channel quality indicator), the UMTS base station (known as NodeB) is able to modify the effective coding rate and thus increase system efficiency. In Release 99, such adaptive data rate scheduling took place at the RNC (radio network controller) which impacted the cell capacity and edge of cell data rates.
—HSDPA includes a shorter TTI (time transmission interval) of 2 ms, which enables the NodeB scheduler to quickly and efficiently allocate resources to mobiles. In Release 99 the minimum TTI was 10 ms, adding more latency to the packets being transmitted over the air.
HARQ (hybrid automatic repeat request)
—If a packet does not get through to the UE successfully, the system employs HARQ. This improves the retransmission timing, thus requiring less reliance on the RNC. In Release 99, the packet re-transmission was mainly controlled by the physical (PHY) layer as well as the RNC's ARQ (automatic repeat request) algorithm, which was slower in adapting to the radio conditions.
Release 6 adds various features, with HSUPA (high speed uplink packet data) being the key one. HSUPA also goes under the term “enhanced uplink, EUL”. The term HSPA (high speed packet access) is normally used to describe a Release 6 network since an HSUPA call requires HSDPA on the downlink.
The downlink of Release 6 remained the same as in HSDPA of Release 5. The uplink data rate of the HSUPA system can go up to 5.76 Mbps with 2 ms TTI used in the network and devices. The practical uplink data rates deployed are 1.4 and 2 Mbps. It is worth noting that there is a dependence between the downlink and uplink data rates. Even if the user is only downloading data at a high speed, the uplink needs to cope with the packet acknowledgments at the same high speed. Therefore any data rate evolution in the downlink needs to have an evolved uplink as well.
HSUPA, like HSDPA, adds functionalities to improve packet data which include:
—HSUPA has the ability to dynamically change the coding and therefore improves the efficiency of the system.
Fast power scheduling
—A key fact of HSUPA is that it provides a method to schedule the power to different mobiles. This scheduling can use either a 2 or 10 ms TTI. 2 ms usually reveals a challenge on the uplink interference and coverage when compared to 10 ms TTI operation. Hence, a switch between the two TTI is possible within the same EUL data call.
—Like HSDPA, HSUPA also utilizes HARQ concepts in lower layers. The main difference is the timing relationship for the retransmission and the synchronized HARQ processes.
The main addition to this release is HSPA+, also known as evolved HSPA. During the commercialization of HSPA, LTE system development has been started, promising a more enhanced bandwidth and system capacity. Evolution of the HSPA system was important to keep up with any competitor technologies and prolong the lifetime of UMTS systems.
HSPA+ provides various enhancements to improve PS data delivery. The features in HSPA+ have been introduced as add-ons. The operators typically evaluate the best options of HSPA+ features for deployment interests, based on the traffic increase requirements, flexibility, and the cost associated for the return of investment. HSPA+ in Release 7 includes:
—This is added to the downlink and enables HSPA+ to operate at a theoretical rate of 21.6 Mbps.
—This is added to the uplink and enables the uplink to theoretically achieve 11.76 Mbps.
MIMO (multiple input multiple output) operation
—This offers various capacity benefits including the ability to reach a theoretical 28.8 Mbps data rate in the downlink.
Power and battery enhancements
—Various enhancements such as CPC (continuous packet connectivity) have been included. CPC enables DTX (discontinuous transmission) and DRX (discontinuous reception) functions in connected mode.
Less data packet overhead
—The downlink includes an enhancement to the lower layers in the protocol stack. This effectively means that fewer headers are required, and in turn, improves the system efficiency.
On the HSPA+ side, Release 8 has continued to improve the system efficiency and data rates by providing:
MIMO with 64 QAM modulation
—It enables the combination of 64 QAM and MIMO, thus reaching a theoretical rate of 42 Mbps, that is, 2 × 21.6 Mbps.
Dual cell operation
—DC-HSDPA (dual cell high speed downlink packet access) is a feature which is further enhanced in Releases 9 and 10. It enables a mobile to effectively utilize two 5 MHz UMTS carriers. Assuming both are using 64 QAM (21.6 Mbps), the theoretical data rate is 42 Mbps. DC-HSDPA has gained the primary interest over other Release 8 features, and most networks are currently either supporting it or in the deployment stage.
Further power and battery enhancements
—deploys a feature known as enhanced fast dormancy as well as enhanced RRC state transitions.
The 3GPP Release 8 defines the first standardization of the LTE specifications. The evolved packet system (EPS) is defined, mandating the key features and components of both the radio access network (E-UTRAN, evolved universal terrestrial radio access network) and the CN (evolved packet core, EPC). Orthogonal frequency division multiplexing is defined as the air interface with the ability to support multi-layer data streams using MIMO antenna systems to increase spectral efficiency.
LTE is defined as an all-IP network topology differentiated over the legacy CS domain. However, the Release 8 specification makes use of the CS domain to maintain compatibility with the 2G and 3G systems utilizing the voice calls circuit switch Fallback (CSFB) technique for any of those systems.
LTE in Release 8 has a theoretical data rate of 300 Mbps. The most common deployment is 100 to 150 Mbps with a full usage of the bandwidth, 20 MHz. Several other variants are also deployed in less bandwidth and hence with lower data rates. The bandwidth allocation is tied to the amount of spectrum acquired by the LTE network operators in every country.
The motivations and different options discussed in 3GPP for the EPS network architecture have been detailed in several standardized technical reports in [1–4].
Even though LTE is a Release 8 system, it is further enhanced in Release 9. There are a number of features in Release 9. One of the most important is the support of additional frequency bands and additional enhancements to CSFB voice calls from LTE.
On the HSPA+ side, Release 9 and beyond continued to build on the top of previous HSPA+ enhancements by introducing DC-HSUPA, MIMO + DC-HSDPA, and multi-carrier high speed downlink packet access (MC-HSDPA). The downlink of HSPA+ in this release is expected to reach 84 Mbps, while the uplink can reach up to 42 Mbps.
Release 10 includes the standardization of LTE Advanced, the 3GPP's 4G offering. It includes modification to the LTE system to facilitate 4G services. The requirements of ITU are to develop a system with increased data rates up to 1 Gbps in the downlink and 500 Mbps in the uplink. Other requirements of ITU's 4G are worldwide roaming and compatibility of services. LTE-Advanced is now seeing more interest, especially from the operators who have already deployed LTE in early stages.
As discussed in this 3GPP evolution, the 4G system is designed to refer to LTE-Advanced. However, since UMTS has been widely used as a 3G system, investing in and building up an ecosystem for an LTE network using the same “3G” term would have been misinterpreted. Hence, regulators in most countries have allowed the mobile operators to use the term “4G” when referring to LTE. This book considers the term 4G when referring to an LTE system, especially for the concepts that are still common between LTE and LTE-Advanced.
This chapter describes the overall architecture of an LTE CN, radio access protocols, and air interface procedures. This chapter and the upcoming parts of the book focus on Release 8 and 9 of the 3GPP specifications. The last chapter of the book gives an overview of the features beyond Release 9.
In wireless cellular systems, mobile users share a common medium for transmission. There are various categories of assignment. The main four are FDMA (frequency division multiple access), TDMA, CDMA, and OFDMA (orthogonal frequency division multiple access). Each of the technologies discussed earlier in the chapter utilizes one of these techniques. This is another reason for distinguishing the technologies.
In order to accommodate various devices on the same wireless network, FDMA divides the available spectrum into sub-bands or channels. Using this technique, a dedicated channel can be allocated to a user, while other users occupy other channels or frequencies.
FDMA channels can suffer from higher interference. They cannot be close together due to the energy from one transmission affecting the adjacent or neighboring channels. To combat this, additional guard bands between channels are required, which also reduces the system's spectral efficiency. The uplink or downlink receiver must use filtering to mitigate interference from other users.
In TDMA systems the channel bandwidth is shared in the time domain. It assigns a relatively narrow spectrum allocation to each user, but in this case the bandwidth is shared between a set of users. Channelization of users in the same band is achieved by a separation in both frequency and time. The number of timeslots in a TDMA frame is dependent on the system. For example, GSM utilizes eight timeslots.
TDMA systems are digital and therefore offer security features such as ciphering and integrity. In addition, they can employ enhanced error detection and correction schemes including FEC (forward error correction). This enables the system to be more resilient to noise and interference and therefore they have a greater spectral efficiency than FDMA systems.
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