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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
CONVERGED COMMUNICATIONS A one-of-a-kind exploration of the past, present, and future of telecommunications In Converged Communications: Evolution from Telephony to 5G Mobile Internet, telecommunications industry veteran Erkki Koivusalo delivers an essential reference describing how different communications systems work, how they have evolved from fixed telephone networks to the latest 5G mobile systems, and how the voice and data services converged. The central theme of the book is to build deeper understanding about incremental technological progress by introducing both state of the art and their predecessor technologies. The book explores four main areas, including fixed telephone systems, data communication systems, mobile cellular systems, and IP multimedia systems. It clearly explains architectures, protocols, and functional procedures, and discusses a variety of topics ranging from physical layer processes to system level interactions. Converged -Communications offers: * In-depth treatments of fixed telephone and transmission systems, including operation of telephone exchanges and signaling systems * Comprehensive explorations of data communication systems, including transmission of data over telephone lines and data network technologies, such as Ethernet and TCP/IP * Incisive discussions of mobile cellular systems, including GSM, 3G, LTE, VoLTE and 5G * Insightful analysis of incremental system evolution to justify various design choices made The book is supported with extensive online appendices, which covers communication system concepts, an overview of standardization, various technologies used in the past, state-of-the art technologies such as WLAN, cable modems, and FTTx, complementing the other systems described in the book which have evolved from the fixed telephone network. Perfect for network operators, system integrators, and communication system vendors, Converged Communications: Evolution from Telephony to 5G Mobile Internet will also earn a place in the libraries of undergraduate and graduate students studying telecommunications and mobile systems. Constructive comments and improvement proposals about Converged Communications or its online appendices can be sent by email to address [email protected]. The feedback will be considered for possible new editions of the book or the revisions of the appendices.
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Table of Contents
Cover
Series Page
Title Page
Copyright Page
Preface
Acknowledgments
Acronyms
About the Companion Website
Introduction – The Evolution
References
Part I: Advanced clinical practice
1 Fixed Telephone Networks
1.1 Telephone Network
1.2 Telephone Exchange and Signaling Systems
1.3 Transmission Networks
1.4 Questions
References
Part II: Data Communication Systems
2 Data over Telephony Line
2.1 Subscriber Line Data Technologies
2.2 Asymmetric Digital Subscriber Line
2.3 VDSL
2.4 Questions
References
3 Data Network Technologies
3.1 Data Link Protocols
3.1.3 HDLC and LLC
3.2 Switching Protocols for Virtual Connections
3.3 Internet Protocol Version 4
3.4 Internet Protocol Version 6
3.5 IP Routing
3.6 Web Browsing with HTTP Protocol
3.7 Questions
References
Part III: Mobile Cellular Systems
4 Cellular Networks
4.1 Cellular Networking Concepts
4.2 History of Cellular Technologies
4.3 First Generation
4.4 Questions
References
5 Second Generation
5.1 GSM
5.2 General Packet Radio Service
5.3 EDGE
5.4 Questions
References
6 Third Generation
6.1 Universal Mobile Telecommunications System (UMTS)
6.2 High‐Speed Packet Access
6.3 Questions
References
7 Fourth Generation
7.1 LTE and SAE
7.2 Questions
References
Part IV: IP Multimedia Systems
8 Fifth Generation
8.1 5G
8.2 Questions
References
9 Convergence
9.1 Voice over Internet Protocol (VoIP) and IP Multimedia
9.2 SIP Systems
9.3 3GPP IP Multimedia Subsystem
9.4 Voice over LTE
9.5 IMS Voice over 5G NR
9.6 Voice over WiFi
9.7 Questions
References
Summary – The Transformation
Index
End User License Agreement
List of Tables
Chapter 1
Table 1.1 DTMF dual frequency plan.
Table 1.2 PDH signal multiplexing hierarchy.
Table 1.3 SDH multiplexing hierarchy.
Chapter 2
Table 2.1 Types of standardized narrowband modems.
Table 2.2 Summary of DSL technologies.
Table 2.3 ADSL AS bearers.
Table 2.4 ADLS ANSI market transport classes.
Table 2.5 ADLS ETSI market transport classes.
Table 2.6 ADSL ATM transport classes.
Chapter 3
Table 3.1 WLAN variants.
Chapter 5
Table 5.1 Functional areas of GSM.
Table 5.2 GPRS coding schemes.
Table 5.3 EGPRS modulation and coding schemes.
Table 5.4 EGPRS2 coding schemes.
Chapter 8
Table 8.1 5G NR frame versus LTE frame.
Summary
Table S.1 Share of voice and data from the total network traffic.
Table S.2 Share of voice and data from the mobile network traffic.
List of Illustrations
Chapter 1
Figure 1.1 Time representation of voice waveform.
Figure 1.2 Concept of PCM sampling.
Figure 1.3 Operation of PCM quantization.
Figure 1.4 Telephone network structure.
Figure 1.5 Analog phone system.
Figure 1.6 Physical structure of a telephone exchange.
Figure 1.7 Logical structure of a telephone exchange.
Figure 1.8 Operation of the switching matrix in time and space dimensions [8...
Figure 1.9 SS7 protocol stack.
Figure 1.10 Structures of T1 and E1 frames.
Figure 1.11 PDH multiplexer mountain.
Figure 1.12 SDH multiplexing structure up to STM‐4.
Figure 1.13 Building AUG‐1 from C‐4.
Figure 1.14 SDH network example.
Figure 1.15 Connecting virtual containers in SDH cross‐connect.
Figure 1.16 EDFA amplifier.
Chapter 2
Figure 2.1 Analog modem connection over telephone network.
Figure 2.2 Structure of an ADSL system.
Figure 2.3 ADSL multiplexer located at a local multiplexer site.
Figure 2.4 ADSL multiplexer in a central office – double wiring case.
Figure 2.5 DMT modulated signal in the end of the subscriber line.
Figure 2.6 ADSL interleaving process.
Figure 2.7 Mapping of ADSL2 frame bearers and two latency paths to frames.
Figure 2.8 ADSL2 functional block model.
Figure 2.9 ADSL2 PMD transmitter block diagram.
Figure 2.10 ADSL frame structure as specified within ITU‐T G.992.1.
Figure 2.11 Structure of a message on the eoc channel.
Figure 2.12 VDSL band allocation.
Figure 2.13 VDSL2 PMD transmitter block diagram.
Figure 2.14 VDSL frame structure for slow and fast latency paths.
Figure 2.15 VDSL2 frame structure for two latency paths.
Chapter 3
Figure 3.1 Examples of Ethernet LAN networks.
Figure 3.2 Ethernet frame.
Figure 3.3 Different topologies of HDLC link.
Figure 3.4 The structure of control field within HDLC frame.
Figure 3.5 MPLS packets and label switching with forwarding equivalence clas...
Figure 3.6 OSI model versus the traditional TCP/IP protocol stack.
Figure 3.7 Structure of the Internet.
Figure 3.8 IPv4 address structure, original design for different network cla...
Figure 3.9 Network address translation.
Figure 3.10 Structure of the IPv4 packet.
Figure 3.11 Structure of TCP segment.
Figure 3.12 Structure of SCTP message.
Figure 3.13 Structure of a DNS message.
Figure 3.14 IP address allocation process over DHCP.
Figure 3.15 Structure of DHCP message.
Figure 3.16 IPsec ESP for tunnel and transport modes.
Figure 3.17 Structure of IPSec AH and ESP messages.
Figure 3.18 IPv6 message structure and the extension headers.
Figure 3.19 Routing tables with DVA and link state algorithms for the same n...
Figure 3.20 Transporting HTTP message with an underlying TCP/IP protocol sta...
Figure 3.21 Web browsing session over Internet.
Figure 3.22 Protocol stacks in the network nodes.
Chapter 4
Figure 4.1 Structure of a cellular network.
Figure 4.2 Using a higher number of antennas for
beamforming
results narrowe...
Figure 4.3 Cellular network band allocation pattern using seven subbands (
Eu
...
Figure 4.4 Downstream data rates of GSM and 3GPP cellular technologies.
Figure 4.5 GSM and 3GPP specification releases.
Chapter 5
Figure 5.1 Functional split between GSM network elements.
Figure 5.2 Architecture and interfaces of the GSM system.
Figure 5.3 GSM control plane signaling protocols.
Figure 5.4 Multiplexing on GSM radio interface.
Figure 5.5 GSM frequency hopping scheme used by mobile station.
Figure 5.6 Allocation of GSM physical channels over GSM frame structure.
Figure 5.7 The multiframe structure of GSM radio interface.
Figure 5.8 GSM transmission burst types.
Figure 5.9 Structure of LAPDm frame.
Figure 5.10 Generic structure of RIL3 protocol frame.
Figure 5.11 Paging and opening of dedicated channel for GSM MT call.
Figure 5.12 GSM connection release.
Figure 5.13 Starting GSM encryption.
Figure 5.14 GSM MO call setup.
Figure 5.15 GSM MT call setup.
Figure 5.16 Simplified block diagram of the RPE – LTP encoder.Fair use....
Figure 5.17 GSM short message protocols.
Figure 5.18 GSM SMS.
Figure 5.19 GSM location update.
Figure 5.20 Different types of GSM handover.
Figure 5.21 Inter‐BSC handover under the anchor MSC.
Figure 5.22 Architecture and interfaces of GPRS system.
Figure 5.23 GPRS packet system user plane protocols.
Figure 5.24 PDCHs and radio blocks allocated to the GPRS mobile station with...
Figure 5.25 GPRS transmitter design.
Figure 5.26 Structures of GPRS MAC uplink and downlink frames.
Figure 5.27 Structures of GPRS RLC uplink and downlink data frames.
Figure 5.28 Structure of the GPRS LLC frame.
Figure 5.29 Structure of GPRS SNDCP frame.
Figure 5.30 Buffers of BSSGP protocol.
Figure 5.31 Structure of the GPRS GTP data frame.
Figure 5.32 GPRS downlink channel activation for MT data.
Figure 5.33 GPRS attach procedure.
Figure 5.34 Routing area update for GPRS.
Figure 5.35 GPRS PDP context activation by mobile station.
Chapter 6
Figure 6.1 Functional split between UTRAN and core network elements.
Figure 6.2 Architecture and interfaces of the UMTS system.
Figure 6.3 Bearer architecture of UMTS system.
Figure 6.4 UMTS control plane signaling protocols with ATM option.
Figure 6.5 UMTS user plane protocols in packet switched domain with ATM opti...
Figure 6.6 WCDMA radio protocol stack and channels.
Figure 6.7 WCDMA channelization code tree structure.
Figure 6.8 WCDMA soft handover.
Figure 6.9 Mapping between WCDMA UMTS logical, transport, and physical chann...
Figure 6.10 WCDMA downlink transmitter design.
Figure 6.11 Structure of the WCDMA MAC frame.
Figure 6.12 WCDMA RRC state model and possible state transitions.
Figure 6.13 Structure of the support mode Iu UP frame.
Figure 6.14 Structure of the FP frame.
Figure 6.15 Opening UMTS RRC connection.
Figure 6.16 UMTS MO call setup.
Figure 6.17 UMTS MT call setup.
Figure 6.18 UMTS call release.
Figure 6.19 UMTS PDP context activation.
Figure 6.20 UMTS release of PDP context.
Figure 6.21 UMTS location area update.
Figure 6.22 UMTS active set update for soft handover.
Figure 6.23 Protocol architecture of HSDPA.
Figure 6.24 Mapping between logical, transport, and physical channels with H...
Figure 6.25 Mapping between logical, transport, and physical uplink channels...
Figure 6.26 Protocol architecture of HSUPA.
Chapter 7
Figure 7.1 Functional split between eNodeB and elements of EPC.
Figure 7.2 Architecture and interfaces of the LTE/SAE system.
Figure 7.3 Bearer architecture of LTE system.
Figure 7.4 LTE user plane protocols.
Figure 7.5 LTE control plane signaling protocols.
Figure 7.6 LTE radio protocol stack and channels.
Figure 7.7 Spectrum of an LTE subcarrier and the orthogonality of OFDM subca...
Figure 7.8 LTE resource grid.
Figure 7.9 LTE frame structure.
Figure 7.10 Mapping of LTE physical channels into LTE resource grid.
Figure 7.11 Mapping between LTE logical, transport, and physical channels....
Figure 7.12 LTE downlink transmitter design.
Figure 7.13 GTP‐U tunneling.
Figure 7.14 LTE UE initial access.
Figure 7.15 Opening LTE RRC connection.
Figure 7.16 Authentication in LTE.
Figure 7.17 Starting LTE encryption and integrity protection.
Figure 7.18 Opening initial default EPS bearer.
Figure 7.19 Opening additional default EPS bearers.
Figure 7.20 Opening dedicated EPS bearer.
Figure 7.21 Disconnecting from a packet data network.
Figure 7.22 LTE tracking area update.
Figure 7.23 Inter‐cell X2 handover in LTE.
Figure 7.24 Inter‐RAT handover from LTE to UMTS.
Figure 7.25 User data paths before, during, and after inter‐RAT handover.
Figure 7.26 Circuit switched fallback with PSHO for MT voice call – idle UE....
Figure 7.27 MT SMS over SG.
Chapter 8
Figure 8.1 5G network slicing.
Figure 8.2 Functional split between gNB and key elements of 5GC (adapted fro...
Figure 8.3 Architecture and interfaces of standalone 5G system.
Figure 8.4 5G packet system user plane protocols.
Figure 8.5 5G control plane signaling protocols.
Figure 8.6 NR radio protocol stack and channels (adapted from 3GPP TS 38.300...
Figure 8.7 5G QoS architecture (adapted from 3GPP TS 38.300 [3]).
Figure 8.8 The 5G NR frame structure from gNB to UE.
Figure 8.9 DM‐RS type 2 configuration with front‐loaded DM‐RS signals only....
Figure 8.10 Increasing the uplink coverage with supplementary uplink (adapte...
Figure 8.11 Non‐standalone EN‐DC NR dual connectivity with LTE supported by ...
Figure 8.12 NR SSB block structure.
Figure 8.13 NR UE initial access and registration.
Figure 8.14 Opening NR RRC connection.
Figure 8.15 Resuming NR RRC connection.
Figure 8.16 NR service request.
Figure 8.17 Authentication and NAS security in 5G.
Figure 8.18 5G PDU session establishment.
Figure 8.19 Activation of PDU sessions in 5G registration area update.
Figure 8.20 5G PDU session modification.
Figure 8.21 5G PDU session release.
Figure 8.22 Registration due to NR UE mobility.
Figure 8.23 NR RAN notification area update.
Figure 8.24 Inter‐cell handover in NR.
Figure 8.25 Receiving MT SMS over 5G NAS.
Chapter 9
Figure 9.1 End‐to‐end VoIP call.
Figure 9.2 SIP VoIP system within a VoIP service provider domain.
Figure 9.3 Architecture of IMS.
Figure 9.4 IMS proxy discovery and registration.
Figure 9.5 IMS voice call setup.
Figure 9.6 LTE attach and bearer setup for VoLTE registration.
Figure 9.7 VoLTE call before and after 3GPP Rel‐8 SRVCC handover.
Figure 9.8 SRVCC Rel‐8 handover.
Figure 9.9 VoLTE call before and after 3GPP SRVCC handover with ATCF and ATG...
Figure 9.10 VoLTE emergency call.
Figure 9.11 SMS over IP.
Figure 9.12 VoWiFi network architecture and interfaces.
Guide
Summary – The Transformation
Cover Page
Series Page
Title Page
Copyright Page
Preface
Acknowledgments
Acronyms
About the Companion Website
Introduction – The Evolution
Table of Contents
Begin Reading
Index
WILEY END USER LICENSE AGREEMENT
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IEEE Press445 Hoes LanePiscataway, NJ 08854
IEEE Press Editorial BoardSarah Spurgeon, Editor in Chief
Jón Atli Benediktsson
Andreas Molisch
Diomidis Spinellis
Anjan Bose
Saeid Nahavandi
Ahmet Murat Tekalp
Adam Drobot
Jeffrey Reed
Peter (Yong) Lian
Thomas Robertazzi
Converged Communications
Evolution from Telephony to 5G Mobile Internet
Erkki Koivusalo
Advisor at Sofigate in Espoo, Finland
Copyright © 2023 by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.
Published by John Wiley & Sons, Inc., Hoboken, New Jersey.Published simultaneously in Canada.
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Preface
This book has two basic goals. First of all, it explains to the reader how different fixed and mobile communications systems work when delivering data or media such as voice calls between remote communication parties. But another, perhaps not too obvious, point behind its story is to provide the reader with evolutionary understanding about why those systems look as they do. The book paints a broad picture of communication systems evolution from the early analog telephone networks with manually operated switches to the latest 5G mobile data networks.
To achieve its mission, this book is divided into five parts that together describe the pieces of a jigsaw puzzle of the evolution that has taken place in the world of telephony and wide area data communications:
Part I
: Fixed Telephone Systems
Part II
: Data Communications Systems
Part III
: Mobile Cellular Systems
Part IV
: IP Multimedia Systems
Online Appendices ‐
https://www.wiley.com/go/koivusalo/convergedcommunications
Part I describes the structure and protocols related to fixed telephone networks. After walking through the network architecture and its elements, the book describes the operation of a digital telephone network and its key building blocks – digital exchange and connecting trunk lines. Operation of a fixed digital telephone network is controlled by SS7 signaling protocol suite, which deserves some attention as the first protocol stack introduced by the book, also used in second‐ and third‐generation mobile networks. Further on, Part I briefly explains the early approach to provide a fully digital data communication path over telephony network with ISDN. The final chapters of Part I provide insight on various transmission technologies used in fixed telephone access and trunk networks, with which both voice and data are transported between different elements of the network.
Part II is focused to data transmission and familiarizes the reader with commonly used link, network, and transport layer solutions. There are various compelling reasons to take data communications methods under study. First of all, the control mechanisms within any digital network are based on signaling data protocols. But what is even more significant from the perspective of this book is the evolution of networks from voice‐only systems to systems carrying both voice and data and eventually to data‐only systems where voice appears only as one small use case of all‐IP data communications. Part II begins by introducing usage of telephony subscriber line to transport data with analog and digital modems. The next two topics are data link protocols and switching protocols that support virtual connections over the network. The last sections of Part II deal with IP network protocol and TCP/IP protocol suite, on which the current all‐IP data networks are based. Due to the significance of the Internet protocol (IP) for modern Internet‐based communications, the book describes two major versions of the protocol, IPv4 and IPv6, as well as the other main protocols of the TCP/IP suite.
Part III elaborates the evolution of mobile cellular networks from the first‐generation analog cellular systems to the latest fifth‐generation 5G cellular data system. For each generation of cellular systems, one specific system and its enhanced variants are explained. The focus of this part is to describe systems that are currently maintained or being developed within 3GPP standardization forum, as since the fourth‐generation cellular technologies, only 3GPP solutions have been deployed all over the world. Part III starts with a generic description about what a cellular system is and what are the related concepts and functions. Thereafter, the book takes a brief look into NMT as one example of a first‐generation analog cellular system. The main body of the part walks through technologies like GSM, GPRS, WCDMA UMTS, HSPA, LTE, and 5G. For each of those, the reader learns how the technology was specified, what were the goals and services to be provided, what does the system architecture look like, what kind of protocols does the system use, and how various system‐wide procedures have been implemented.
Part IV eventually brings the topics of data and telephony together. The concept of convergence, providing voice or multimedia as a service of packet data network, is introduced. As practical implementations, the book explains how a basic SIP VoIP system works and how voice calls are supported in mobile operator domain with 3GPP IP Multimedia Subsystem (IMS) architecture. The final sections of Part III elaborate how the IMS mechanisms are bundled together with the underlying LTE or 5G New Radio access technologies as VoLTE and VoNR services.
Appendices cover telecommunications theory and technologies competing on complementary with those which have their roots in telephone network. Visit The Online Appendix A at https://www.wiley.com/go/koivusalo/convergedcommunications for access to online only materials which introduce the reader to the problem space of telecommunications. The reader gets familiar with the major challenges that the communications system designers face, to be addressed in the system design. For each challenge, standard solutions as known to the communications industry are briefly walked through. This part provides the reader with basic knowledge of telecommunications concepts and mechanisms needed to be able to comprehend the rest of the real‐life systems as described in the rest of the book. The approach is qualitative, to introduce the reader with important terminology and the related functionality. Apart from the very basics, neither mathematical equations nor complex theoretical background are provided, as those might be difficult to grasp and are not necessary to understand functionality of system implementations. The reader is expected to have a basic understanding of physics related to electro‐magnetic phenomena, to understand how electrical pulses propagate in cables and radio waves in space. Part I describes how such phenomena is applied for communications with different mechanisms as referred by the other four parts of the book. Other appendices describe technologies like WLAN, WiMAX cable modems, and Fiber‐to‐X.
Material of the book enables the reader to understand how each of the described technologies work, master the key terminology used with them, identify the similarities and differences between related systems, recognize the strengths and weaknesses of their technical choices, understand the context and limitations of the technologies coming from their historical perspective, and navigate in the specification jungles as available from various standardization forums. The book has some coverage of telecommunication theory and generic mechanisms but is focused to describe practical systems evolved over decades of engineering effort. The author of the book hopes the material will be useful for various interest groups including but not limited to students of telecommunications, data communications and mobile systems; staff working on network operators; members of different standardization forums; engineers designing new communications systems or specific device implementations. This book can be used as an introduction to wide area communications systems for anyone from newcomers to the topic to knowledgeable engineers who are specialized to some technologies but want to broaden their understanding about other related systems and technologies. The book is well suited for a university‐level course of introduction to telecommunications technologies.
Acknowledgments
I would like to give special thanks to the members of my manuscript review team: Hannu Bergius, George Denissoff, Lauri Eerolainen, Jarkko Hellsten, Markus Isomäki, Petri Jarre, Mika Jokinen, Pasi Junttila, Mika Kasslin, Timo Lassila, Ari Laukkanen, Jussi Leppälä, Mika Liljeberg, Georg Mayer, Marko Ovaska, Arto Peltomäki, Antti Pihlajamäki, Jussi Silander, Ari Valve, and Jukka Vikstedt. These former colleagues gave many invaluable technical comments and suggestions of how to improve the structure and language of the book; they identified gaps in the covered areas, checked facts, and provided their insight about actual deployments. Big thanks also to Wiley team members who supported with crafting the book according to my vision. I am grateful to Sandra Grayson, Senior Commissioning Editor at Wiley, for successfully promoting my book during the proposal and contract stage. Thanks to Juliet Booker, Managing Editor, for actively guiding me through content development up to delivery of the final manuscript to Wiley. Ranjith Kumar Thanigasalam, Permissions Specialist, helped me check and correctly cite copyrighted material used from other organizations. My copy editor, Christine Sabooni, improved and polished the language throughout the book given I am a non‐native writer of English. Additional thanks to Content Refinement Specialist, Ashok Ravi, who acted as my main contact during the typesetting and proofreading stages. Without their combined assistance the manuscript would have remained in a drawer, at my home. Last but not least, I would like to express the gratitude I have for my family members: my wife, Maarit, my daughters, Paula and Anni; and my son, Mikko. They have encouraged me to take the necessary steps and time to get this book completed and published. I have now done my part. Thank you for reading this book.
Acronyms
3GPP
3rd Generation Partnership Project
5GC
5G Core
5QI
5G QoS Identifier
AAL
ATM adaptation layer
ABM
Asynchronous balanced mode
ACELP
Algebraic code excited linear prediction
ACK
Acknowledgment (positive)
ADM
Add‐drop multiplexer
ADSL
Asymmetric digital subscriber line
AF
Application function
AGCH
Access grant channel
AH
Authentication header
AICH
Acquisition indication channel
AIS
Alarm indication signal
AKA
Authentication and Key Agreement
AM
Acknowledged mode
AMF
Access and mobility management function
AMI
Alternating mark inversion
AMPS
Advanced Mobile Phone Service
AMR
Adaptive multi‐rate
ANR
Automatic neighbor relation
AOR
Address of Record
AP
Access point
AP‐AICH
Access preamble acquisition channel
APN
Access point name
APS
Automatic protection switching
ARM
Asynchronous response mode
ARP
Address resolution protocol
ARP
Allocation and retention priority
ARQ
Automatic repeat request
AS
Access stratum
AS
Application server
ASK
Amplitude shift keying
ATM
Asynchronous transfer mode
ATU
ADSL transmission unit
AuC
Authentication center
AUG
Administrative unit group
AUSF
Authenticating server function
AWG
American wire gauge
BC
Billing center
BCC
Bearer channel connection
BCCH
Broadcast control channel
BCH
Broadcast channel
BCM
Basic call model
BEC
Basic error correction
BER
Bit error ratio
BGCF
Breakout gateway control function
BICN
Bearer‐independent core network
BLER
Block error rate
BPI+
Baseline privacy interface plus
BPKM
Baseline privacy key management
BS
Base station
BSC
Base station controller
BSR
Buffer status report
BSS
Base station subsystem
BSS
Basic service set
BSSGP
Base station subsystem GPRS protocol
BSSMAP
Base station subsystem management part
BTS
Base transceiver station
BWP
Bandwidth part
CA
Carrier aggregation
CA‐ICH
Channel assignment indicator channel
CAP
Carrier‐less amplitude/phase
CAS
Channel associated signaling
CBCH
Cell broadcast channel
CC
Component carrier
CCCH
Common control channel
CCE
Control channel element
CCF
Charging collection function
CCITT
Consultative Committee for International Telephony and Telegraphy
CCK
Complementary code keying
CCMP
Counter mode with CBC‐MAC protocol
CCO
Cell change over
CCPCH
Common control physical channel
CCS
Common channel signaling
CD‐ICH
Collision detection indicator channel
CDMA
Code division multiple access
CELP
Code excited linear prediction
CGI
Cell global identity
CIC
Circuit identification code
CIDR
Classless inter‐domain routing
CM
Cable modem
CM
Communication management
CMTS
Cable modem termination system
CN
Core network
COO
Changeover order
CPC
Continuous packet connectivity
CPE
Customer premises equipment
CPCH
Common packet channel
CPICH
Common pilot channel
CPS
Coding and puncturing scheme
CQI
Channel quality indicator
CRC
Cyclic redundancy check
CRNC
Controlling radio network controller
CRS
Cell‐specific reference signal
CS
Circuit switched
CSCF
Call state control function
CSD
Circuit switched data
CSFB
Circuit switched fallback
CSI
Channel state information
CSICH
CPCH status indication channel
CSMA/CD
Carrier sense multiple access with collision detection
CSPDN
Circuit switched public data network
CTCH
Common traffic channel
CUPS
Control and user plane separation
DAPS
Dual active protocol stack
DBA
Dynamic bandwidth assignment
DC
Dual connectivity
DCCH
Dedicated control channel
DCF
Distributed coordination function
DCH
Dedicated channel
DCI
Downlink control information
DCS
Digital communications system
DHCP
Dynamic host configuration protocol
DLCI
Data link connection identifier
DL‐SCH
Downlink shared channel
DM‐RS
Demodulation reference signal
DMT
Discrete multitone
DNN
Data network name
DNS
Domain name system
DP
Detection point
DOCSIS
Data over cable service interface specification
DPC
Destination point code
DPCCH
Dedicated physical control channel
DPDCH
Dedicated physical data channel
DPLL
Digital phase‐locked loop
DRB
Data radio bearer
DRNC
Drifting radio network controller
DRX
Discontinuous reception
DS
Distribution system
DSCH
Downlink shared channel
DSL
Digital subscriber line
DSS
Digital signature standard
DSS
Dynamic spectrum sharing
DSSS
Direct sequence spread spectrum
DTAP
Direct transfer application part
DTCH
Dedicated traffic channel
DTMF
Dual‐tone multifrequency
DTX
Discontinuous transmission
DXC
Digital cross‐connect switch
DVA
Distance‐vector algorithm
EAE
Early authentication and encryption
E‐AGCH
E‐DCH absolute grant channel
ECF
Event charging function
ECO
Emergency changeover
ECSD
Enhanced circuits switched data
E‐DCH
Enhanced dedicated channel
EDFA
Erbium‐doped fiber amplifier
EDGE
Enhanced data rates for global evolution
EDP
Event detection point
E‐DPCCH
Enhanced dedicated physical control channel
E‐DPDCH
Enhanced dedicated physical data channel
EDT
Early data transfer
EFM
Ethernet in the first mile
EFR
Enhanced full‐rate
EGPRS
Enhanced general packet radio service
E‐HICH
E‐DCH HARQ indicator channel
EIR
Equipment identity register
eMBB
Enhanced mobile broadband
EMM
EPS mobility management
EOW
Engineering orderwire
EPC
Evolved packet core
ePDG
Evolved packet data gateway
EPS
E‐UTRAN packet system
E‐RGCH
E‐DCH relative grant channel
ERP
Extended rate physical
ESM
EPS session management
ESP
Encapsulation security payload
ESS
Extended service set
ETSI
European Telecommunications Standards Institute
E‐UTRAN
Evolved UMTS terrestrial radio access network
FACCH
Fast associated control channel
FACH
Forward access channel
FBSS
Fast BS switching
FCCH
Frequency correction channel
FCS
Frame check sequence
FDD
Frequency division duplex
FDM
Frequency division multiplexing
FDMA
Frequency division multiple access
FEC
Forward error correction
FEC
Forwarding equivalence class
FGI
Feature group indicator
FHSS
Frequency hopping spread spectrum
FISU
Fill‐in signal unit
FP
Frame protocol
FR
Frequency range
FR
Frame relay
FSK
Frequency shift keying
FTTB
Fiber to the building
FTTC
Fiber to the curb
FTTH
Fiber to the home
FTTN
Fiber to the node
FTTx
Fiber To X
GBR
Guaranteed bit rate
GCID
GPRS charging identifier
GEM
G‐PON encapsulation method
GERAN
GSM EDGE radio access network
GFSK
Gaussian frequency shift keying
GGSN
Gateway GPRS support node
GMM
GPRS mobility management
GMSC
Gateway mobile switching center
GMSK
Gaussian minimum shift keying
gNB
5G Node B
GPON
Gigabit‐capable passive optical networks
GPRS
General packet radio service
GRUU
Globally routable UA URI
GSM
Global system for mobile communications
GSMA
GSM Association
GT
Global title
GTP
GPRS tunneling protocol
GUA
Global unicast address
GUTI
Global unique temporary identity
GW
Gateway
HARQ
Hybrid automatic repeat request
HDB3
high density bipolar 3
HDLC
High‐level data link
HDSL
High‐speed digital subscriber line
HFC
Hybrid fiber‐coaxial
HLR
Home location register
HSCSD
High‐speed circuit switched data
HSDPA
High‐speed downlink packet access
HS‐DPCCH
High‐speed dedicated physical control channel
HS‐DSCH
High‐speed downlink shared channel
HSN
Hopping sequence number
HSPA
High‐speed packet access
HSS
Home subscriber server
HS‐SCCH
High‐speed shared control channel
HSUPA
High‐speed uplink packet access
HTTP
Hypertext transfer protocol
HTU
HDSL termination unit
IAM
Initial address message
IANA
Internet Assigned Numbers Authority
IAP
Internet access point
ICANN
Internet Corporation for Assigned Names and Numbers
ICIC
Inter‐cell interference coordination
ICID
IMS charging identifier
ICMP
Internet control message protocol
ICSI
IMS communication service identifier
IMT
International mobile telecommunication
IUC
Interval usage code
IETF
Internet Engineering Task Force
IKE
Internet key exchange
IMEI
International mobile equipment identity
IMPI
IP multimedia private identity
IMPU
IP multimedia public identity
IMS
IP multimedia subsystem
IMSI
International mobile subscriber identity
IN
Intelligent network
IoT
Internet of things
IP
Internet protocol
IPSec
IP Security
IPX
IP roaming exchage
IR
Incremental redundancy
ISDN
Integrated Services Digital Network
ISI
Intersymbol interference
ISIM
IP multimedia services identity module
ISM
Industrial, scientific, and medical
ISO
International Standardization Organization
ISP
Internet service provider
ITU
International Telecommunications Union
ISUP
ISDN user part
IWF
Interworking function
Kbps
Kilobits per second
LA
Link adaptation
LAI
Location area identity
LAN
Local access network
LAPD
Link access procedure for channel D
LC
Link control
LCP
Link control protocol
LDP
Label distribution protocol
LDPC
Low‐density‐parity‐check
LED
Light‐emitting diodes
LLC
Logical link control
LPC
Linear prediction coding
LRF
Location retrieval function
LS
Link security
LSA
Link state algorithm
LSP
Link state packet
LSR
Label switched router
LSSU
Link status signal unit
LTE
Long‐term evolution
LTP
Long‐term prediction
LTU
Line termination unit
M3UA
MTP3 user adaptation layer
MAC
Medium access control
MAC
Message authentication code
MAIO
Mobile allocation index offset
Mbps
Megabits per second
MBR
Maximum bit rate
MCC
Mobile country code
MCCH
Multicast control channel
MCG
Master cell group
MCH
Multicast channel
MCS
Modulation and coding scheme
MDF
Main distribution frame
MDHO
Macro diversity handover
ME
Mobile equipment
MF
Multifrequency
MGCF
Media gateway control function
MGW
Media gateway
MIB
Master information block
MIMO
Multiple input, multiple output
MM
Mobility management
MME
Mobility management entity
MMS
Multimedia message
mMTC
Massive machine type communication
MMTel
Multimedia telephony
MNC
Mobile network code
MOS
Mean opinion score
MoU
Memorandum of Understanding
MPOA
Multi‐protocol over ATM
MPLS
Multi‐protocol label switching
MRFC
Multimedia resource function controller
MRFP
Multimedia resource function processor
MS
Mobile station
MS
Multiplex section
MSC
Mobile switching center
MSISDN
Mobile station ISDN number
MSP
Multiplex section protection
MSRN
Mobile station roaming number
MSRP
Message session relay protocol
MSU
Message signal unit
MTC
Machine type communication
MTCH
Multicast traffic channel
MTP
Message transfer part
MTRF
Mobile terminating roaming forwarding
MTU
Maximum transfer unit
MTX
Mobile telephone exchange
MUX
Multiplexer
NAI
Network access identifier
NACK
Negative acknowledgement
NAS
Non‐access stratum
NAT
Network address translation
NBAP
Node B application protocol
NCP
Network control protocol
NEF
Network exposure function
NGAP
NG application protocol
NIC
Network information center
NID
Network interface device
NMT
Nordic Mobile Telephone
NR
New Radio
NRF
Network repository function
NRM
Normal response mode
NRZI
Non‐return‐to‐zero‐inverted
NSS
Network and switching subsystem
NSSAI
Network slice selection assistance information
NSSF
Network slice selection function
NTU
Network termination unit
NWDAF
Network data analytics function
OAM
Operation and maintenance
OCC
Orthogonal cover code
ODN
Optical distribution network
OFDM
Orthogonal frequency division multiplexing
OFDMA
Orthogonal frequency division multiple access
OH
Overhead
OLT
Optical line termination
OMCI
ONT management and control interface
ONT
Optical network termination
ONU
Optical network unit
OPC
Originating point code
OSI
Open systems interconnection
OSPF
Open shortest path first
OSS
Operations and support subsystem
PABX
Private branch exchange
PACCH
Packet associated control channel
PAD
Packet assembler and disassembler
PAGCH
Packet access grant channel
PBCCH
Packet broadcast control channel
PBCH
Physical broadcast channel
PC
Protection control
PCC
Policy and charging control
PCCCH
Packet common control channel
PCCH
Paging control channel
PCF
Policy and charging function
PCF
Point coordination function
PCFICH
Physical control format indicator channel
PCH
Paging channel
PCM
Pulse code modulation
PCPCH
Physical common packet channel
PCR
Preventive cyclic retransmission
PCRF
Policy and charging rule function
PCU
Packet control unit
PDCCH
Physical downlink control channel
PDCH
Packet data channel
PDCP
Packet data convergence protocol
PDH
Plesiochronous digital hierarchy
PDN
Packet data network
PDPC
Packet data protocol context
PDSCH
Physical downlink shared channel
PDTCH
Packet data traffic channel
PDU
Protocol data unit
PEI
Permanent equipment identifier
PFCP
Packet forwarding control protocol
P‐GW
Packet data network gateway
PH
Packet handler
PHICH
Physical HARQ indicator channel
PIC
Point in call
PICH
Paging indication channel
PKI
Public key infrastructure
PLCP
Physical layer convergence procedure
PLMN
Public land mobile network
PLOAM
Physical layer operations, administration and maintenance
PMCH
Physical multicast channel
PMD
Physical medium dependent
PMI
Precoding matrix indicator
PMS‐TC
Physical medium specific transmission convergence
PNCH
Packet notification channel
PON
Passive optical networking
POTS
Plain old telephone service
PPCH
Packet paging channel
PPP
Point‐to‐point protocol
PRACH
Packet random access channel
PRACH
Physical random access channel
PRC
Primary reference clock
PS
Packet switched
PSA
PDU session anchor
PSAP
Public safety answering point
PSC
Primary scrambling code
PSCH
Primary synchronization channel
PSD
Power spectral density
PSH
Payload header suppression
PSHO
Packet switched handover
PSK
Phase shift keying
PSPDN
Packet switched public data network
PSTN
Public switched telephone network
PSS
Primary synchronization signal
PTCCH
Packet timing control channel
P‐TMSI
Packet temporary mobile subscriber identity
PT‐RS
Phase tracking reference signal
PUCCH
Physical uplink control channel
PUSCH
Physical uplink shared channel
PVC
Permanent virtual circuit
QAM
Quadrature amplitude modulation
QoS
Quality of service
QFI
QoS flow identifier
QPSK
Quadrature phase shift keying
RA
Rate adapter
RA
Routing area
RACH
Random access channel
RAB
Radio access bearer
RAI
Release assistance indication
RAI
Routing area identifier
RAN
Radio access network
RANAP
Radio access network application protocol
RAND
Random number
RAR
Random access response
RAT
Radio access technology
REG
Regenerator
REG
Resource element group
RFC
Request for Comments
RI
Rank indicator
RIL
Radio interface layer
RIP
Routing information protocol
RLC
Radio link control
RNA
RAN‐based notification area
RNC
Radio network controller
RNSAP
Radio network subsystem application protocol
RNTI
Radio network temporary identity
RPE‐LTP
Regular pulse excitation‐long‐term prediction
RRC
Radio resource control
RRM
Radio resource management
RS
Regenerator section
RSPR
Reference signal received power
RTCP
Real time control protocol
RTP
Real time protocol
S1AP
S1 application protocol
SA
Security association
SACCH
Slow associated control channel
SAE
System architecture evolution
SAE
Simultaneous authentication of equals
SAPI
Service access point identifier
SCCP
Signaling connection control part
SCF
Session charging function
SC‐FDMA
Single‐carrier frequency division multiple access
SCG
Secondary cell group
SCH
Synchronization channel
SCP
Service control point
SCS
Subcarrier spacing
SCTP
Stream control transmission protocol
SD
Slice differentiator
SDAP
Service data adaptation protocol
SDCCH
Stand‐alone dedicated control channel
SDH
Synchronous digital hierarchy
SDP
Session description protocol
SDU
Service data unit
SEC
SDH equipment clock
SEPP
Security edge protection proxy
SF
Single frequency
SF
Spreading factor
SFD
Start frame delimiter
SFID
Service flow identifier
SGsAP
SG application protocol
SGSN
Serving GPRS support node
S‐GW
Serving gateway
SHDSL
Single‐pair high‐speed digital subscriber line
SIB
System information block
SID
Service ID
SigComp
Signaling compression
SIGTRAN
Signaling transport
SIM
Subscriber identity module
SIP
Session initiation protocol
SIR
Signal‐to‐interference ratio
SLF
Subscriber locator function
SLS
Signaling link selector
SM
Security management
SM
Session management
SM‐CP
Short message control protocol
SMF
Session management function
SM‐RL
Short message relay layer
SM‐RP
Short message relay protocol
SMS
Short messaging service
SMSC
Short message center
SMSF
Short message service function
SMS‐SC
Short message service serving center
SM‐TL
Short message transfer layer
SNDCP
Subnetwork dependent convergence protocol
SNR
Signal‐to‐noise ratio
SPF
Shortest path first
SPI
Security parameter index
SRES
Expected response
SRNC
Serving radio network controller
SRS
Sounding reference signal
SRU
SHDSL regenerator unit
SRVCC
Single radio voice call continuity
SS
Subscriber station
SS7
Signaling System Number 7
SSB
SS/PCBH block
SSCH
Secondary synchronization channel
SSDT
Site selection diversity
SSID
Service set identity
SSM
Synchronization status message
SSP
Service switching point
SSRC
Synchronization source
SSS
Secondary synchronization signal
SST
Slice/service type
STM
Synchronous transport module
STP
Signaling transfer points
STU
SHDSL transceiver unit
STX
Start of text
SUCI
Subscription concealed identifier
SUL
Supplementary uplink
SUPI
Subscription permanent identifier
SVC
Switched virtual connection
SYN
Synchronization
TA
Terminal adapter
TACS
Total access communication system
TAU
Tracking area update
TBF
Temporary block flow
TC
Transmission convergence
TCAP
Transaction capabilities application part
TCH
Traffic channel
TCP
Transmission control protocol
TDD
Time division duplex
TDM
Time division multiplexing
TDMA
Time division multiple access
TDP
Trigger detection point
TE
Terminal equipment
TEID
Tunnel endpoint identifier
TFCI
Transport format combination identifier
TFI
Temporary flow identifier
TFT
Traffic flow template
TIM
Traffic indication map
TKIP
Temporal key integrity protocol
TLLI
Temporary logical link identifier
TLS
Transport layer security
TLV
Type‐length‐value
TM
Transmission mode
TM
Transparent mode
TMSI
Temporary mobile subscriber identity
TPC
Transmit power control
TPS‐TC
Transmission protocol specific transmission convergence
TRAU
Transcoder and rate adapter unit
TRX
Transceiver
TS
Technical specification
TS
Timeslot
TTI
Transmission time interval
TUG
Tributary unit group
TUP
Telephone user part
UA
User agent
UDM
Unified data management
UDP
User datagram protocol
UDR
Unified data repository
UE
User equipment
UICC
Universal integrated circuit card
UL‐SCH
Uplink shared channel
UM
Unacknowledged mode
UMTS
Universal Mobile Telecommunications System
UNI
User network interface
UPF
User plane function
UPS
Uninterruptible power supply
URA
UTRAN registration area
URI
Uniform resource identifiers
URLLC
Ultra reliable low latency communication
USB
Universal serial bus
USF
Uplink state flag
USIM
UMTS subscriber identity module
UTP
Unshielded twisted pair
UTRAN
UMTS terrestrial radio access network
VAD
Voice activity detection
VC
Virtual circuit
VC
Virtual container
VDSL
Very high‐speed digital subscriber line
VLR
Visitor location register
VoIP
Voice over IP
VoLGA
Voice over LTE via generic access
VoLTE
Voice over LTE
VoNR
Voice over 5G New Radio
VoWiFi
Voice over WiFi
VPN
Virtual private network
WAN
Wide area network
WCDMA
Wideband CDMA
WDM
Wavelength division multiplexing
WEP
Wireless equivalent privacy
WiMAX
Worldwide Interoperability for Microwave Access
WLAN
Wireless local area network
WPA
WiFi protected access
X2AP
X2 application protocol
XnAP
Xn application protocol
About the Companion Website
From the website you can find the following online appendices:
Appendix A Challenges and solutions of communication systems
Appendix B Signaling System 7 and Intelligent Network call model
Appendix C Integrated Services Digital Network
Appendix D Fixed telephone access and transmission systems
Appendix E Digital subscriber line technologies
Appendix F Cable data access
Appendix G Wireless data access
Appendix H ATM systems
Appendix I Cellular systems
Appendix J Session Initiation Protocol suite
Appendix K Answers to questions
The companion website can be found at
www.wiley.com/go/koivusalo/convergedcommunications
Introduction – The Evolution
Since the emergence of spoken language, humans have always had a need to communicate remotely with peers located far away. Caravans and postal services have carried written letters, and American Indians used smoke as a method for quick communication over long distances. The discovery of electricity and radio waves made it possible to send signals over long distances with the speed of light, using wired or radio connections. Modern communications mechanisms, such as 5G radio access or VDSL Internet access, use sophisticated methods to provide the end users with stable, always on, high‐speed connections with global reach to various services. It is a long way from smoke signals to 5G, so let's take a tour to see how all that happened.
The era of modern communications, powered with electricity, began during the 1800s along with various inventions related to electricity itself and later on the radio waves. In the early 1880s, a number of scientists made groundbreaking findings on electricity and magnetism. That eventually led Samuel Morse to create a telegraphy system, where letters were sent over a wire as morse code of short and long beeps. Around the same time, Alexander Bell created his telephone, which was able to capture and reproduce voice with help of a microphone and loudspeaker. The voice waveform was transmitted between two telephones over a set of wires in analog electrical form. Only a few years later, in 1892, Almon Strowger introduced a design for an automated telephone switch [1]. Sometime earlier in the 1860s James Maxwell was able to create a theory about electromagnetic radiation. The theory was verified a few years later. Just in the end of the century, Guglielmo Marconi created a wireless telegraphy system where morse code was sent over radio rather than wire. These early examples demonstrate how the development of technology was powered by scientific findings and innovations about how to apply those findings to communications.
In the first half of the 1900s, radio technology was developed further so that voice could be transmitted over radio and not only over wires. Electronic components, such as diodes and vacuum tubes, were invented, enabling mass market production of radio equipment. The period between World Wars made a leap for radio broadcast systems, and advances were made also for bidirectional radio communications devices, which could be used from vehicles or airplanes. Just before World War II, an important invention was done by Alec Reeves, who presented a way to represent voice in digital form by pulse code modulation (PCM) [2]. Technology was not yet available to implement PCM at war time. Another major invention was frequency hopping radio, which Hedy Lamarr and George Antheil had developed for torpedo guidance systems during wartime.
In the middle of the 1900s, the first steps toward digital communications were taken. Transistors were invented and time division multiplexing was applied for telephony. The first computers were built. In the 1960s, commercial production of integrated circuits started, automatic electronics telephone switches were put into service, and PCM was applied to voice trunks. The laser was invented in the 1960s. By the end of the 1960s, breakthroughs were made for optical transmission technologies with which it was possible to send signal over optical cable rather than electrical.
Digitalization of the telephone network was started and continued throughout the 1970s. From the end of the 1960s onwards, computers were used for specific purposes, such as business, defense, and science. First steps were taken to create packet switched protocols, to support data communications between computers. In the Arpanet project, Internet protocol was used to create resilient networks able to survive over loss of some nodes and links. Still in the business world, data was moved between companies over the telephone network in a totally different way, by scanning paper documents and sending them over to recipients as telefaxes. Telefax technology was adopted in the 1970s and was in common use throughout the following decade.
During the 1980s, businesses used analog modems for moving data over the telephone network between their different offices and business partners. The first analog cellular mobile systems were put into commercial service and standardization of second generation digital cellular systems was started. As telephone exchanges and trunk networks were already digitalized with the help of SS7 protocol suite, ISDN was specified to bring fully digital 64 kbps data channel up to the customer premises. At the same time, TCP/IP protocols came to common use by universities to support Internet use cases such as file transfer, newsgroups, and electronic mail.
In the 1990s, the pace of communications technology evolution increased even further. The first fully digital GSM cellular network was taken into commercial use in 1991. In roughly 10 years from the start, GSM had been taken into use in 200 countries by 600 operators and the number of GSM subscribers approached to 1 billion. This expansion was based on a few important factors. GSM was designed to be a scalable system and it performed well. Compared to digging new cables to ground, it was much easier to set up an antenna to cover a rather large area. From a subscriber point of view, GSM became attractive via the introduction of handheld and even pocket‐size mobile phones, supporting short messages in addition to voice calls. Via economies of scale and increased competition, the prices of equipment and services came down.
Last, but not least, GSM came to the market at just the right time. After the World War II, the telephony business had been under tight regulation. Only the big national telephone companies were allowed to operate networks, but it all started to change in the political environment of the 1980s. Deregulation took place all over the world during the 1990s, which meant new business opportunities for new players. Challenger operators obtained licenses for radio spectrum and were allowed to build their own mobile networks.
The last decade of the century was disruptive also for data communications. While the Internet had been a playground of universities and US defense in the 1980s, something important happened in the end of the decade. While working for CERN, Tim Berners‐Lee set up a project to share information in a networked environment as hypertext. Hyperlinks were used to point to referenced documents in remote computers. In a few years, the invention of the World Wide Web, or the Internet as we know it, was born. Early on, only a few academic and public organizations published any Web pages, but soon businesses found the potential of the new technology. The Internet boomed throughout the 1990s, and Internet service providers started to build Internet connections to homes, using new ADSL technology over existing telephone cabling. All this was enabled by the deregulation, especially in the US Internet consumer market, where incumbent operators were forced to open and lend their infrastructure for other challenger operators.
Very soon, it was found that access to the Internet would be desirable also from mobile terminals. Unfortunately, the rigid structure of circuit switched GSM made it difficult and expensive to support high‐speed, asymmetrical, and variable bitrate Internet connections. In the beginning of the 2000s, GSM networks were enhanced with new GPRS technology, capable of allocating GSM timeslots for packet data traffic dynamically. Still the GPRS data rates stayed modest and latencies long, compared with what ADSL was able to deliver for fixed network customers.
As the need for mobile data access grew, third generation mobile networks, such as WCDMA UMTS and CDMA2000, were specified to support both circuit switched voice and packet switched data in an equal way. UMTS adopted its core network solution from GSM and GPRS, while the radio access technology was completely revamped. UMTS networks were deployed from 2001 onwards. In Europe, deployment was temporarily slowed down by operator economics. Many national states in Europe found out that their right of licensing radio spectrum was a valuable asset. They decided to arrange public auctions from 2000–2001 to grant licenses to operators for using radio spectrum allocated to third generation UMTS systems. Encouraged by the success of GSM, anticipating high returns for 3G investment, and being afraid of becoming locked out of the market, many operators ended up with rather high bids. However, just from 2000 onwards the global telecom boom cooled down. Operators had used high sums of money for 3G licenses and saw their business expectations declining just when they should have invested in building their networks. Based on these experiences, the pricing within later 4G auctions was much more conservative.
Initially, UMTS data rates were expected to support data rates up to 2 Mbps, but in the first networks only a few hundred bps were achieved. That initial disappointment was, however, resolved in a few years by introducing high‐speed packet access (HSPA) technology as an enhancement to WCDMA networks. Smaller cell sizes were introduced to increase spectral efficiency over the network. At the same time, VDSL technology was developed to provide enhanced data rates to homes using interior telephony cabling, assuming that the last mile connection from the building to the network would be supported by optical fiber. During the first decade of the 2000s, mobile phones became so common that the number of fixed telephones started to decline. Eventually, fixed telephony became obsolete over the next 20 years for many developed markets. Old telephony subscriber lines were still used in digital data modem connections, but even the last remaining traditional types of table phones were gradually replaced with ones using cellular radio network rather than any cable, other than the one needed for power.
When the design of fourth‐generation cellular technology was on the drawing board, a very important decision was made. Support for circuit switched connections would not be built at all for the new system. Instead, the 4G system was optimized only for packet switched data. It was seen that data consumption expanded so rapidly that the share of voice traffic became marginal. On the other hand, in the world of digital mobile communications, voice could be represented as data. It was deemed that voice would become a type of data application, just with very specific needs for stable and guaranteed Quality of Service. Convergence was the development where voice and data came together, sharing common mechanisms in the networks, rather than being two inherently different types of services relying on separate network designs.
4G LTE networks were in commercial use from 2010 onwards, and the very first commercial LTE network was launched on December 2009 in Scandinavia. Initially, no voice support was provided in LTE networks, and any 4G handsets had to fall back to using other 3G or 2G radio technologies for the duration of a voice call. Later, in 2015, operators started to open their VoLTE services as 3GPP compliant operator VoIP over LTE. VoLTE complemented the LTE networks to provide native voice support without switching over to other radio technologies. At the time of this writing, only a few operators provide VoLTE roaming service; thus, there is still demand for GSM or UMTS telephony by international travelers or in rural areas without LTE coverage [3]. LTE was successful in providing consumers with superior data service, with high bitrates between 10‐100 Mbps and latencies of a few milliseconds over radio access.
At the same time, operators gradually lost part of their voice market share to Internet applications, such as Skype, Facetime, Hangouts, and WhatsApp supporting one‐to‐one calls or Zoom and Teams supporting multiparty multimedia conferences. All these applications also support instant messaging. Instead of being an operator core service, voice and messaging became a commodity supported by many different application communities. Operators were often no longer able to bill their customers with call minutes or by number of messages sent. Instead, they introduced billing models based on monthly flat fees, data volumes, or data rates provided.
But the world of communications is never ready. While operators were busy with building their LTE networks, the fifth‐generation 5G cellular system technology was already on the drawing board in 3GPP. The LTE OFDMA radio technology uses radio spectrum already very efficiently, close to the theoretical maximum, but 5G New Radio essentially reused its method and structures. Higher bitrates could be provided by increased bandwidth and using very high, hitherto unused sub‐6GHz and mmW frequencies above 24 GHz. In addition to the consumer broadband market, 5G was specified to support other use cases which either needed very low power consumption (IoT, sensor networks) or very high reliability and low latencies (self‐driving cars, surgical operations, factory automation). The first 5G networks were in commercial use in 2019.
The following figure shows the overall timeline over which various wide area network technologies were introduced and rolled out since mid‐1970s. The arrows depict evolution and impact from earlier technologies to the design of later ones.
As can be understood from the earlier description, new telecommunications systems and technologies no longer emerge from a vacuum. New designs are not created from scratch. Instead, every new step of technology is built on top of previous technologies already deployed when the new technology was crafted. Communications technologies are developed in an evolutionary rather than revolutionary manner. To fully understand why a specific system was designed as it was, you need to understand the context in which the system specifications were created. The context has technical, political, and economic aspects. Knowing the virtues of prevailing technologies provides the background for setting the goals and making the technological choices for the next generation of technology.
