From GSM to LTE-Advanced Pro and 5G

An Introduction to Mobile Networks and Mobile Broadband
Wiley (Verlag)
  • 3. Auflage
  • |
  • erschienen am 2. August 2017
  • |
  • 544 Seiten
E-Book | ePUB mit Adobe-DRM | Systemvoraussetzungen
978-1-119-34693-7 (ISBN)
A comparative introduction to major global wireless standards, technologies and their applications
From GSM to LTE-Advanced Pro and 5G: An Introduction to Mobile Networks and Mobile Broadband, 3rd Edition provides technical descriptions of the various wireless technologies currently in use. It explains the rationales behind their differing mechanisms and implementations while exploring the advantages and limitations of each technology.
This edition has been fully updated and substantially expanded to reflect the significant evolution in mobile network technology occurring over the past several years. The chapter on LTE has been extensively enhanced with new coverage of current implementations of LTE carrier aggregation, mobility management, cell reselection and handover procedures, as well as the latest developments in 5G radio and core networks in 3GPP. It now features additional information on the TD-LTE air interface, IPv6 in mobile networks, Network Function Virtualization (NFV) and Narrowband Internet of Things (NB-IOT). Voice-over-LTE (VoLTE) is now treated extensively in a separate chapter featuring coverage of the VoLTE call establishment process, dedicated bearer setup, header compression, speech codec and bandwidth negotiation, supplementary service configuration and VoLTE emergency calls. In addition, extensive coverage of Voice-over-Wifi and mission critical communication for public safety organizations over LTE has been added. The WLAN chapter now provides coverage of WPA2-Professional with certificates for authentication in large deployments, such as the global Eduroam network and the new WLAN 60 GHz air interface. Bluetooth evolution has been addressed by including a detailed description of Bluetooth Low Energy (BLE) in the chapter devoted to Bluetooth.
* Describes the different systems based on the standards, their practical implementation and design assumptions, and the performance and capacity of each system in practice is analyzed and explained
* Questions at the end of each chapter and answers on the accompanying website make this book ideal for self-study or as course material.
3. Auflage
  • Englisch
  • Newark
  • |
  • Großbritannien
John Wiley & Sons
  • 34,20 MB
978-1-119-34693-7 (9781119346937)
weitere Ausgaben werden ermittelt
Martin Sauter works in the telecommunication industry as a thought leader, researcher, book author and blogger and is based in Cologne. His interests are focused on mobile communication networks, multimedia applications and especially the wireless Internet.
  • Intro
  • Title Page
  • Copyright Page
  • Contents
  • Preface
  • Chapter 1 Global System for Mobile Communications (GSM)
  • 1.1 Circuit-Switched Data Transmission
  • 1.1.1 Classic Circuit Switching
  • 1.1.2 Virtual Circuit Switching over IP
  • 1.2 Standards
  • 1.3 Transmission Speeds
  • 1.4 The Signaling System Number 7
  • 1.4.1 The Classic SS-7 Protocol Stack
  • 1.4.2 SS-7 Protocols for GSM
  • 1.4.3 IP-Based SS-7 Protocol Stack
  • 1.5 The GSM Subsystems
  • 1.6 The Network Subsystem
  • 1.6.1 The Mobile Switching Center (MSC), Server and Gateway
  • 1.6.2 The Visitor Location Register (VLR)
  • 1.6.3 The Home Location Register (HLR)
  • 1.6.4 The Authentication Center
  • 1.6.5 The Short Messaging Service Center (SMSC)
  • 1.7 The Base Station Subsystem (BSS) and Voice Processing
  • 1.7.1 Frequency Bands
  • 1.7.2 The Base Transceiver Station (BTS)
  • 1.7.3 The GSM Air Interface
  • 1.7.4 The Base Station Controller (BSC)
  • 1.7.5 The TRAU for Voice Encoding
  • 1.7.6 Channel Coder and Interleaver in the BTS
  • 1.7.7 Ciphering in the BTS and Security Aspects
  • 1.7.8 Modulation
  • 1.7.9 Voice Activity Detection
  • 1.8 Mobility Management and Call Control
  • 1.8.1 Cell Reselection and Location Area Update
  • 1.8.2 The Mobile-Terminated Call
  • 1.8.3 Handover Scenarios
  • 1.9 The Mobile Device
  • 1.9.1 Architecture of a Voice-Centric Mobile Device
  • 1.9.2 Architecture of a Smartphone
  • 1.10 The SIM Card
  • 1.11 The Intelligent Network Subsystem and CAMEL
  • Questions
  • References
  • Chapter 2 General Packet Radio Service (GPRS) and EDGE
  • 2.1 Circuit-Switched Data Transmission over GSM
  • 2.2 Packet-Switched Data Transmission over GPRS
  • 2.3 The GPRS Air Interface
  • 2.3.1 GPRS vs. GSM Timeslot Usage on the Air Interface
  • 2.3.2 Mixed GSM/GPRS Timeslot Usage in a Base Station
  • 2.3.3 Coding Schemes
  • 2.3.4 Enhanced Datarates for GSM Evolution (EDGE)
  • 2.3.5 Mobile Device Classes
  • 2.3.6 Network Mode of Operation
  • 2.3.7 GPRS Logical Channels on the Air Interface
  • 2.4 The GPRS State Model
  • 2.5 GPRS Network Elements
  • 2.5.1 The Packet Control Unit (PCU)
  • 2.5.2 The Serving GPRS Support Node (SGSN)
  • 2.5.3 The Gateway GPRS Support Node (GGSN)
  • 2.6 GPRS Radio Resource Management
  • 2.7 GPRS Interfaces
  • 2.8 GPRS Mobility Management and Session Management (GMM/SM)
  • 2.8.1 Mobility Management Tasks
  • 2.8.2 GPRS Session Management
  • Questions
  • References
  • Chapter 3 Universal Mobile Telecommunications System (UMTS) and High-Speed Packet Access (HSPA)
  • 3.1 Overview, History and Future
  • 3.1.1 3GPP Release 99: The First UMTS Access Network Implementation
  • 3.1.2 3GPP Release 4: Enhancements for the Circuit-Switched Core Network
  • 3.1.3 3GPP Release 5: High-Speed Downlink Packet Access
  • 3.1.4 3GPP Release 6: High-Speed Uplink Packet Access (HSUPA)
  • 3.1.5 3GPP Release 7: Even Faster HSPA and Continued Packet Connectivity
  • 3.1.6 3GPP Release 8: LTE, Further HSPA Enhancements and Femtocells
  • 3.1.7 3GPP Release 9: Digital Dividend and Dual-Cell Improvements
  • 3.1.8 3GPP Releases 10 and Beyond
  • 3.2 Important New Concepts of UMTS
  • 3.2.1 The Radio Access Bearer (RAB)
  • 3.2.2 The Access Stratum and Non-Access Stratum
  • 3.2.3 Common Transport Protocols for CS and PS
  • 3.3 Code Division Multiple Access (CDMA)
  • 3.3.1 Spreading Factor, Chip Rate and Process Gain
  • 3.3.2 The OVSF Code Tree
  • 3.3.3 Scrambling in Uplink and Downlink Direction
  • 3.3.4 UMTS Frequency and Cell Planning
  • 3.3.5 The Near-Far Effect and Cell Breathing
  • 3.3.6 Advantages of the UMTS Radio Network Compared to GSM
  • 3.4 UMTS Channel Structure on the Air Interface
  • 3.4.1 User Plane and Control Plane
  • 3.4.2 Common and Dedicated Channels
  • 3.4.3 Logical, Transport and Physical Channels
  • 3.4.4 Example: Network Search
  • 3.4.5 Example: Initial Network Access Procedure
  • 3.4.6 The Uu Protocol Stack
  • 3.5 The UMTS Terrestrial Radio Access Network (UTRAN)
  • 3.5.1 Node-B, Iub Interface, NBAP and FP
  • 3.5.2 The RNC, Iu, Iub and Iur Interfaces, RANAP and RNSAP
  • 3.5.3 Adaptive Multirate (AMR) NB and WB Codecs for Voice Calls
  • 3.5.4 Radio Resource Control (RRC) States
  • 3.6 Core Network Mobility Management
  • 3.7 Radio Network Mobility Management
  • 3.7.1 Mobility Management in the Cell-DCH State
  • 3.7.2 Mobility Management in Idle State
  • 3.7.3 Mobility Management in Other States
  • 3.8 UMTS CS and PS Call Establishment
  • 3.9 UMTS Security
  • 3.10 High-Speed Downlink Packet Access (HSDPA) and HSPA+
  • 3.10.1 HSDPA Channels
  • 3.10.2 Shorter Delay Times and Hybrid ARQ (HARQ)
  • 3.10.3 Node-B Scheduling
  • 3.10.4 Adaptive Modulation and Coding, Transmission Rates and Multicarrier Operation
  • 3.10.5 Establishment and Release of an HSDPA Connection
  • 3.10.6 HSDPA Mobility Management
  • 3.11 High-Speed Uplink Packet Access (HSUPA)
  • 3.11.1 E-DCH Channel Structure
  • 3.11.2 The E-DCH Protocol Stack and Functionality
  • 3.11.3 E-DCH Scheduling
  • 3.11.4 E-DCH Mobility
  • 3.11.5 E-DCH-Capable Devices
  • 3.12 Radio and Core Network Enhancements: CPC and One Tunnel
  • 3.12.1 A New Uplink Control Channel Slot Format
  • 3.12.2 CQI Reporting Reduction and DTX and DRX
  • 3.12.3 HS-SCCH Discontinuous Reception
  • 3.12.4 HS-SCCH-less Operation
  • 3.12.5 Enhanced Cell-FACH and Cell/URA-PCH States
  • 3.12.6 Radio Network Enhancement: One Tunnel
  • 3.13 HSPA Performance in Practice
  • 3.13.1 Throughput in Practice
  • 3.13.2 Radio Resource State Management
  • 3.13.3 Power Consumption
  • 3.14 Automated Emergency Calls (eCall) from Vehicles
  • 3.15 UMTS and CDMA2000
  • Questions
  • References
  • Chapter 4 Long Term Evolution (LTE) and LTE-Advanced Pro
  • 4.1 Introduction and Overview
  • 4.2 Network Architecture and Interfaces
  • 4.2.1 LTE Mobile Devices and the LTE Uu Interface
  • 4.2.2 The eNode-B and the S1 and X2 Interfaces
  • 4.2.3 The Mobility Management Entity (MME)
  • 4.2.4 The Serving Gateway (S-GW)
  • 4.2.5 The PDN-Gateway
  • 4.2.6 The Home Subscriber Server (HSS)
  • 4.2.7 Billing, Prepaid and Quality of Service
  • 4.3 FDD Air Interface and Radio Network
  • 4.3.1 OFDMA for Downlink Transmission
  • 4.3.2 SC-FDMA for Uplink Transmission
  • 4.3.3 Quadrature Amplitude Modulation for Subchannels
  • 4.3.4 Reference and Synchronization Signals
  • 4.3.5 The LTE Channel Model in the Downlink Direction
  • 4.3.6 Downlink Management Channels
  • 4.3.7 System Information Messages
  • 4.3.8 The LTE Channel Model in the Uplink Direction
  • 4.3.9 MIMO Transmission
  • 4.3.10 HARQ and Other Retransmission Mechanisms
  • 4.3.11 PDCP Compression and Ciphering
  • 4.3.12 Protocol Layer Overview
  • 4.4 TD-LTE Air Interface
  • 4.5 Scheduling
  • 4.5.1 Downlink Scheduling
  • 4.5.2 Uplink Scheduling
  • 4.6 Basic Procedures
  • 4.6.1 Cell Search
  • 4.6.2 Attach and Default Bearer Activation
  • 4.6.3 Handover Scenarios
  • 4.6.4 Default and Dedicated Bearers
  • 4.7 Mobility Management and Power Optimization
  • 4.7.1 Mobility Management in RRC Connected State
  • 4.7.2 Mobility Management in RRC Idle State
  • 4.7.3 Mobility Management and State Changes in Practice
  • 4.8 LTE Security Architecture
  • 4.9 Interconnection with UMTS and GSM
  • 4.9.1 Cell Reselection between LTE and GSM/UMTS
  • 4.9.2 RRC Connection Release with Redirect between LTE and GSM/UMTS
  • 4.9.3 Handover from LTE to UMTS
  • 4.10 Interworking with CDMA2000 Networks
  • 4.10.1 Cell Reselection between LTE and CDMA2000 Networks
  • 4.10.2 RRC Connection Release with Redirect between LTE and CDMA2000
  • 4.10.3 Handover between LTE and CDMA2000
  • 4.11 Carrier Aggregation
  • 4.11.1 CA Types, Bandwidth Classes and Band Combinations
  • 4.11.2 CA Configuration, Activation and Deactivation
  • 4.12 Network Planning Aspects
  • 4.12.1 Single Frequency Network
  • 4.12.2 Cell-Edge Performance
  • 4.12.3 Self-Organizing Network Functionality
  • 4.13 CS-Fallback for Voice and SMS Services with LTE
  • 4.13.1 SMS over SGs
  • 4.13.2 CS-Fallback for Voice Calls
  • 4.14 Voice in Combined LTE and CDMA2000 Networks (SV-LTE)
  • 4.15 Network Sharing - MOCN and MORAN
  • 4.15.1 National Roaming
  • 4.15.2 MOCN (Multi-Operator Core Network)
  • 4.15.3 MORAN (Mobile Operator Radio Access Network)
  • 4.16 From Dipoles to Active Antennas and Gigabit Backhaul
  • 4.17 IPv6 in Mobile Networks
  • 4.17.2 IPv6 and International Roaming
  • 4.17.3 IPv6 and Tethering
  • 4.17.4 IPv6-Only Connectivity
  • 4.18 Network Function Virtualization
  • 4.18.1 Virtualization on the Desktop
  • 4.18.2 Running an Operating System in a Virtual Machine
  • 4.18.3 Running Several Virtual Machines Simultaneously
  • 4.18.4 Virtual Machine Snapshots
  • 4.18.5 Cloning a Virtual Machine
  • 4.18.6 Virtualization in Data Centers in the Cloud
  • 4.18.7 Managing Virtual Machines in the Cloud
  • 4.18.8 Network Function Virtualization
  • 4.18.9 Virtualizing Routers
  • 4.18.10 Software-Defined Networking
  • 4.19 Machine Type Communication and the Internet of Things
  • 4.19.1 LTE Cat-1 Devices
  • 4.19.2 LTE Cat-0 Devices and PSM
  • 4.19.3 LTE Cat-M1 Devices
  • 4.19.4 LTE NB1 (NB-IoT) Devices
  • 4.19.5 NB-IoT - Deployment Options
  • 4.19.6 NB-IoT - Air Interface
  • 4.19.7 NB-IoT - Control Channels and Scheduling
  • 4.19.8 NB-IoT Multicarrier Operation
  • 4.19.9 NB-IoT Throughput and Number of Devices per Cell
  • 4.19.10 NB-IoT Power Consumption Considerations
  • 4.19.11 NB-IoT - High Latency Communication
  • 4.19.12 NB-IoT - Optimizing IP-Based and Non-IP-Based Data Transmission
  • 4.19.13 NB-IoT Summary
  • 4.20 Other Features of LTE-Advanced and LTE-Advanced Pro
  • 4.20.1 8?×?8 Downlink and 4?×?4 Uplink MIMO
  • 4.20.2 Relays
  • 4.20.3 HetNets, ICIC and eICIC
  • 4.20.4 Coordinated Multipoint Operation
  • 4.21 From LTE to 5G
  • 4.21.1 New Radio for 5G
  • 4.21.2 Radio Network Evolution for 5G
  • 4.21.3 Core Network Evolution for 5G
  • Questions
  • References
  • Chapter 5 VoLTE, VoWifi and Mission Critical Communication
  • 5.1 Overview
  • 5.2 The Session Initiation Protocol (SIP)
  • 5.3 The IP Multimedia Subsystem (IMS) and VoLTE
  • 5.3.1 Architecture Overview
  • 5.3.2 Registration
  • 5.3.3 VoLTE Call Establishment
  • 5.3.4 LTE Bearer Configurations for VoLTE
  • 5.3.5 Dedicated Bearer Setup with Preconditions
  • 5.3.6 Header Compression and DRX
  • 5.3.7 Speech Codec and Bandwidth Negotiation
  • 5.3.8 Alerting Tone, Ringback Tone and Early Media
  • 5.3.9 Port Usage
  • 5.3.10 Message Filtering and Asserted Identities
  • 5.3.11 DTMF Tones
  • 5.3.12 SMS over IMS
  • 5.3.13 Call Forwarding Settings and XCAP
  • 5.3.14 Single Radio Voice Call Continuity
  • 5.3.15 Radio Domain Selection, T-ADS and VoLTE Interworking with GSM and UMTS
  • 5.3.16 VoLTE Emergency Calls
  • 5.4 VoLTE Roaming
  • 5.4.1 Option 1: VoLTE Local Breakout
  • 5.4.2 Option 2: VoLTE S8-Home Routing
  • 5.5 Voice over WiFi (VoWifi)
  • 5.5.1 VoWifi Network Architecture
  • 5.5.2 VoWifi Handover
  • 5.5.3 Wi-Fi-Preferred vs. Cellular-Preferred
  • 5.5.4 SMS, MMS and Supplementary Services over Wi-Fi
  • 5.5.5 VoWifi Roaming
  • 5.6 VoLTE Compared to Fixed-Line IMS in Practice
  • 5.7 Mission Critical Communication (MCC)
  • 5.7.1 Overview
  • 5.7.2 Advantages of LTE for Mission Critical Communication
  • 5.7.3 Challenges of Mission Critical Communication for LTE
  • 5.7.4 Network Operation Models
  • 5.7.5 Mission Critical Push To Talk (MCPTT) - Overview
  • 5.7.6 MCPTT Group Call Establishment
  • 5.7.7 MCPTT Floor Control
  • 5.7.8 MCPTT Group Call Types
  • 5.7.9 MCPTT Configuration and Provisioning
  • 5.7.10 eMBMS for MCPTT
  • 5.7.11 Priority and Quality of Service
  • Questions
  • References
  • Chapter 6 Wireless Local Area Network (WLAN)
  • 6.1 Wireless LAN Overview
  • 6.2 Transmission Speeds and Standards
  • 6.3 WLAN Configurations: From Ad Hoc to Wireless Bridging
  • 6.3.1 Ad Hoc, BSS, ESS and Wireless Bridging
  • 6.3.2 SSID and Frequency Selection
  • 6.4 Management Operations
  • 6.5 The MAC Layer
  • 6.5.1 Air Interface Access Control
  • 6.5.2 The MAC Header
  • 6.6 The Physical Layer and MAC Extensions
  • 6.6.1 IEEE 802.11b - 11 Mbit/s
  • 6.6.2 IEEE 802.11g with up to 54 Mbit/s
  • 6.6.3 IEEE 802.11a with up to 54 Mbit/s
  • 6.6.4 IEEE 802.11n with up to 600 Mbits/s
  • 6.6.5 IEEE 802.11ac - Gigabit Wireless
  • 6.6.6 IEEE 802.11ad - Gigabit Wireless at 60 GHz
  • 6.7 Wireless LAN Security
  • 6.7.1 Wired Equivalent Privacy (WEP)
  • 6.7.2 WPA and WPA2 Personal Mode Authentication
  • 6.7.3 WPA and WPA2 Enterprise Mode Authentication - EAP-TLS
  • 6.7.4 WPA and WPA2 Enterprise Mode Authentication - EAP-TTLS
  • 6.7.5 WPA and WPA2 Enterprise Mode Authentication - EAP-PEAP
  • 6.7.6 WPA and WPA2 Enterprise Mode Authentication - EAP-SIM
  • 6.7.7 WPA and WPA2 Encryption
  • 6.7.8 Wi-Fi-Protected Setup (WPS)
  • 6.8 IEEE 802.11e and WMM - Quality of Service
  • Questions
  • References
  • Chapter 7 Bluetooth and Bluetooth Low Energy
  • 7.1 Overview and Applications
  • 7.2 Physical Properties
  • 7.3 Piconets and the Master/Slave Concept
  • 7.4 The Bluetooth Protocol Stack
  • 7.4.1 The Baseband Layer
  • 7.4.2 The Link Controller
  • 7.4.3 The Link Manager
  • 7.4.4 The HCI Interface
  • 7.4.5 The L2CAP Layer
  • 7.4.6 The Service Discovery Protocol
  • 7.4.7 The RFCOMM Layer
  • 7.4.8 Overview of Bluetooth Connection Establishment
  • 7.5 Bluetooth Security
  • 7.5.1 Pairing up to Bluetooth 2.0
  • 7.5.2 Pairing with Bluetooth 2.1 and Above (Secure Simple Pairing)
  • 7.5.3 Authentication
  • 7.5.4 Encryption
  • 7.5.5 Authorization
  • 7.5.6 Security Modes
  • 7.6 Bluetooth Profiles
  • 7.6.1 Basic Profiles: GAP, SDP and the Serial Profile
  • 7.6.2 Object Exchange Profiles: FTP, Object Push and Synchronize
  • 7.6.3 Headset, Hands-Free and SIM Access Profile
  • 7.6.4 High-Quality Audio Streaming
  • 7.6.5 The Human Interface Device (HID) Profile
  • 7.7 Bluetooth Low Energy
  • 7.7.1 Introduction
  • 7.7.2 The Lower BLE Layers
  • 7.7.3 BLE SMP, GAP and Connection Establishment
  • 7.7.4 BLE Authentication, Security and Privacy
  • 7.7.5 BLE ATT and GATT
  • 7.7.6 Practical Example
  • 7.7.7 BLE Beacons
  • 7.7.8 BLE and IPv6 Internet Connectivity
  • Questions
  • References
  • Index
  • EULA

Global System for Mobile Communications (GSM)

At the beginning of the 1990s, GSM, the Global System for Mobile Communications, triggered an unprecedented change in the way people communicate with each other. While earlier analog wireless systems were used only by a few, GSM is used worldwide by billions of people today. This has mostly been achieved by steady improvements in all areas of telecommunication technology and the resulting steady price reductions for both infrastructure equipment and mobile devices. This chapter discusses the architecture of this system, which also forms the basis for the packet-switched extension called General Packet Radio Service (GPRS), discussed in Chapter 2, for the Universal Mobile Telecommunications System (UMTS), which is described in Chapter 3 and Long-Term Evolution (LTE), which is discussed in Chapter 4.

Although the first standardization activities for GSM date back to the middle of the 1980s, GSM is still the most widely used wireless technology worldwide. In recent years, however, 4G LTE networks have become tremendously popular and a new service was standardized to support voice calls via the LTE radio network. This service is referred to as Voice over LTE (VoLTE) and is discussed separately in Chapter 5. Although efforts to roll out VoLTE are significant, a large percentage of mobile voice calls are still handled by GSM and UMTS networks to which devices without VoLTE support fall back for this service. In addition, even if a device and a network support VoLTE, a transfer to GSM or UMTS is still required when the user leaves the LTE-coverage area. As a consequence, knowledge of GSM is still required for a thorough understanding of how mobile networks are deployed and used in practice today.

1.1 Circuit-Switched Data Transmission

Initially, GSM was designed as a circuit-switched system that establishes a direct and exclusive connection between two users on every interface between all network nodes of the system. Section 1.1.1 gives a first overview of this traditional architecture. Over time, this physical circuit switching has been virtualized and many network nodes are connected over IP-based broadband connections today. The reasons for this and further details on virtual circuit switching can be found in Section 1.1.2.

1.1.1 Classic Circuit Switching

The GSM mobile telecommunication network has been designed as a circuit-switched network in a similar way to fixed-line phone networks. At the beginning of a call, the network establishes a direct connection between two parties, which is then used exclusively for this conversation. As shown in Figure 1.1, the switching center uses a switching matrix to connect any originating party to any destination party. Once the connection has been established, the conversation is then transparently transmitted via the switching matrix between the two parties. The switching center only becomes active again to clear the connection in the switching matrix if one of the parties wants to end the call. This approach is identical in both mobile and fixed-line networks. Early fixed-line telecommunication networks were designed only for voice communication, for which an analog connection between the parties was established. In the mid-1980s, analog technology was superseded by digital technology in the switching center. This meant that calls were no longer sent over an analog line from the originator to the terminator. Instead, the switching center digitized the analog signal that it received from the subscribers, which were directly attached to it, and forwarded the digitized signal to the terminating switching center. There, the digital signal was again converted back to an analog signal, which was then sent over the copper cable to the terminating party. In some countries, ISDN (Integrated Services Digital Network) lines were quite popular. With this system, the transmission became fully digital and the conversion back to an analog audio signal was done directly in the phone.

Figure 1.1 Switching matrix in a switching center.

GSM reused much of the fixed-line technology that was already available at the time the standards were created. Thus, existing technologies such as switching centers and long-distance communication equipment were used. The main development for GSM, as shown in Figure 1.2, was the means to wirelessly connect the subscribers to the network. In fixed-line networks, subscriber connectivity is very simple as only two dedicated wires are necessary per user. In a GSM network, however, the subscribers are mobile and can change their location at any time. Thus, it is not possible to use the same input and output in the switching matrix for a user for each call as is the case in fixed-line networks.

Figure 1.2 Necessary software changes to adapt a fixed-line switching center for a wireless network.

As a mobile network consists of many switching centers, with each covering a certain geographical area, it is not even possible to predict in advance which switching center a call should be forwarded to for a certain subscriber. This means that the software for subscriber management and routing of calls of fixed-line networks cannot be used for GSM. Instead of a static call-routing mechanism, a flexible mobility management architecture in the core network became necessary, which needed to be aware of the current location of the subscriber and thus able to route calls to them at any time.

It was also necessary to be able to flexibly change the routing of an ongoing call as a subscriber can roam freely and thus might leave the coverage area of the radio transmitter of the network over which the call was established. While there was a big difference between the software of a fixed switching center and a Mobile Switching Center (MSC), the hardware as well as the lower layers of the software which are responsible, for example, for the handling of the switching matrix were mostly identical. Therefore, most telecommunication equipment vendors like Ericsson, Nokia Solutions and Networks, Huawei and Alcatel-Lucent offered their switching center hardware both for fixed-line and mobile networks. Only the software in the switching center determined whether the hardware was used in a fixed or mobile network (see Figure 1.2).

1.1.2 Virtual Circuit Switching over IP

While in the 1990s voice calls were the dominating form of communication, this has significantly changed today with the rise of the Internet. While voice calls remain important, other forms of communication such as e-mail, instant messaging (IM), social networks (e.g. Facebook), blogs, wikis and many more play an even bigger role. All these services share the Internet Protocol (IP) as a transport protocol and globally connect people via the Internet.

While circuit switching establishes an exclusive channel between two parties, the Internet is based on transferring individual data packets. A link with a high bandwidth is used to transfer the packets of many users. By using the destination address contained in each packet, each network node that the packet traverses decides over which outgoing link to forward the packet. Further details can be found in Chapter 2.

Owing to the rise of the Internet and IP-based applications, network operators thus had to maintain two separate networks: a circuit-switched network for voice calls and a packet-switched network for Internet-based services.

As the simultaneous operation of two different networks is very inefficient and costly, most network operators have, in the meantime, replaced the switching matrix in the MSC with a device referred to as a media gateway. This allows them to virtualize circuit switching and to transfer voice calls over IP packets. The physical presence of a circuit-switched infrastructure is thus no longer necessary and the network operator can concentrate on maintaining and expanding a single IP-based network. This approach has been standardized under the name 'Bearer-Independent Core Network' (BICN).

The basic operation of GSM is not changed by this virtualization. The main differences can be found in the lower protocol levels for call signaling and voice call transmission. This will be looked at in more detail in the remainder of this chapter.

The trend toward IP-based communication can also be observed in the GSM radio network especially when a radio base station site supports GSM, UMTS and LTE simultaneously. Typically, connectivity is then established over a single IP-based link.

The air interface between the mobile devices and the network is not affected by the transition from circuit to packet switching. For mobile devices, whether the network uses classic or virtual circuit switching is therefore completely transparent.

1.2 Standards

As many network infrastructure manufacturers compete globally for orders from telecommunication network operators, standardization of interfaces and procedures is necessary. Without standards, which are defined by the International Telecommunication Union (ITU), it would not be possible to make phone calls internationally and network operators would be bound to the supplier they initially select for the delivery of their network components. One of the most important ITU standards,...

Dateiformat: ePUB
Kopierschutz: Adobe-DRM (Digital Rights Management)


Computer (Windows; MacOS X; Linux): Installieren Sie bereits vor dem Download die kostenlose Software Adobe Digital Editions (siehe E-Book Hilfe).

Tablet/Smartphone (Android; iOS): Installieren Sie bereits vor dem Download die kostenlose App Adobe Digital Editions (siehe E-Book Hilfe).

E-Book-Reader: Bookeen, Kobo, Pocketbook, Sony, Tolino u.v.a.m. (nicht Kindle)

Das Dateiformat ePUB ist sehr gut für Romane und Sachbücher geeignet - also für "fließenden" Text ohne komplexes Layout. Bei E-Readern oder Smartphones passt sich der Zeilen- und Seitenumbruch automatisch den kleinen Displays an. Mit Adobe-DRM wird hier ein "harter" Kopierschutz verwendet. Wenn die notwendigen Voraussetzungen nicht vorliegen, können Sie das E-Book leider nicht öffnen. Daher müssen Sie bereits vor dem Download Ihre Lese-Hardware vorbereiten.

Bitte beachten Sie bei der Verwendung der Lese-Software Adobe Digital Editions: wir empfehlen Ihnen unbedingt nach Installation der Lese-Software diese mit Ihrer persönlichen Adobe-ID zu autorisieren!

Weitere Informationen finden Sie in unserer E-Book Hilfe.

Download (sofort verfügbar)

92,99 €
inkl. 7% MwSt.
Download / Einzel-Lizenz
ePUB mit Adobe-DRM
siehe Systemvoraussetzungen
E-Book bestellen