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Mobile Services ST 2010 | 1 Introduction Axel Küpper | Technische Universität Berlin | Service-centric Networking 1 Mobile Services (ST 2010) Chapter 1: Introduction Axel Küpper Service-centric Networking Deutsche Telekom Laboratories, TU Berlin

Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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Page 1: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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1

Mobile Services (ST 2010)Chapter 1: Introduction

Axel Küpper

Service-centric NetworkingDeutsche Telekom Laboratories, TU Berlin

Page 2: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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gMobile ServicesSummer Term 2010

1 Introduction1.1 The Emergence of Mobile Services

1.2 What is a Mobile Service?

1.3 Mobility Classification

1.4 Protocol Overview

1.5 Physical Layer Overview

1.6 Data Link Layer Overview

2

Page 3: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.1 The Emergence of Mobile Services

The Fathers of the Internet

3

Creator of the first computer-

to-computer network based

on packet switching (ARPAnet)

Lawrence Roberts(*1939)

Donald Davies(*1924 †2000)

Paul Baran(*1926)

Leonard Kleinrock(*1934)

Developers of packet switching and the mathematical theory behind it

Joseph C. R. Licklider(*1915 †1990)

Formulated the earliest ideas of a global computer

network

Robert E. Kahn(*1938)

Vint Cerf(*1943)

Inventors of the Transmission Control Protocol (TCP)

Transit networksAccess networks

Local networks

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g1.1 The Emergence of Mobile Services

What is a Service?

4

Transit networksAccess networks

Local networks

Request

Response

ServerClient InterfaceInteraction according to protocol

Examples Email File Transfer Protocol Gopher World Wide Web

Service

Activity of a computer program performed on request for another program

Remotely accessible at well-defined interfaces and offered in a communications system

Invoked and used by protocols of the application layer

Page 5: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.1 The Emergence of Mobile Services

The World Wide Web (I)

5

Transit networksAccess networks

Local networks

GET /hypertext/WWW/TheProject.html

?info.cern.ch

130.094.122.195

DNS

Inventor of the WWW

Tim Berners Lee(*1955)

"I just had to take the hypertext idea and connect it to the Transmission Control

Protocol and domain name system ideas and – tada! – the World Wide Web!"

Interlinked documents, accessible worldwide

Hyper Text Markup Language

Hypertext Transfer Protocol

Uniform Resource Locator

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g1.1 The Emergence of Mobile Services

The World Wide Web (II)

6

Transit networksAccess networks

Local networks

GET gp/product/0470092319/ref=s9_simi_gw_s3_...

Bob

Request

ResponseResponse

?amazon.com ?amazon.com

130.094.122.195130.094.122.195

Several enhancements in the last 15 years focusing on dynamic web pages, session and transaction management, search, asynchronous operation,…

Basis for many applications: content, commerce, control, communication, communities, …

Basis for realizing intra-/interorganizational supply chains → SOA

Page 7: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.1 The Emergence of Mobile Services

Service-oriented Architectures (SoAs)

Service Composition

Interoganizational connection of services

Fixes service logic and control flows, for example, conditional, sequential, parallel, and exceptional execution

Consistent management of data exchanged between services

Service Description

Standard way to specify data and operations of a service (syntax)

Fixes a service's capabilities, behavior, and related service type (semantics)

Defines the conditions of usage (service contracts)

Service Discovery

Public directory that enables the publication of services and facilitates their discovery

Companies can publish specifications of ser-vices they provide and other enterprises can access those services using the descriptions

Software architecture that is based on the key concepts of an application frontend, a service, a service repository, and a service bus.

Krafzig/Banke/Slama: "Neither a technology nor a technology standard, but instead it represents a technology-independent, high-level concept that provides architectural blueprints", for example:

7

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g1.1 The Emergence of Mobile Services

Web 2.0

88

Bob

Co-founder of Web 2.0

Tim O'Reilly (*1954)

Term that represents different concepts and paradigms of latest WWW services:

"The web as a platform" – Software applications are based on the web, not the desktop PC

Democratization – Community service and user-generated content

Mashups – new services through combination of existing services and content

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g1.1 The Emergence of Mobile Services

Peer-to-Peer Environments

9

Transit networksAccess networks

Access networks

Founder and inventor of Napster

Shawn Fanning (*1980)

No dedicated roles of client and server

Overlay network of peers that share resources (bandwidth, computational power, content,…)

Peer is provider and requestor

Motivated by (illegal) mp3 sharing

Page 10: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.1 The Emergence of Mobile Services

Cloud Computing

10

1010111010101010101010111111011010101111

01010111IaaS

SaaS

PaaS

Client(usually web

browser)

Transit networksAccess networks

Local networks

Infrastructure as a Service: virtualization of computer hardware

Platform as a Service: usage of service platforms without the cost and complexity of buying and managing underlying hardware and software layers

Software as a Service: loading software into the user's web browser on demand and executing it there; related data is stored in the cloud

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g1.1 The Emergence of Mobile Services

Integration of Mobile Networks

11

Transit networksAccess/local networks

Ad hoc networks Mesh networks

Cellularnetworks

Interconnectivity with different types of wireless networks: cellular, ad-hoc, mesh,…

Requirement for many new (service) scenarios:

Mobile Internet

Fixed/Mobile Convergence and All-IP

Internet of Things and Services

Ubiquitous Computing and Context-aware Services

Page 12: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.2 What is a Mobile Service?

Some Definitions (I)

Mobile Communications

Transmission of data to and from handheld devices

Out of two or more communicating devices, at least one handheld is mobile

Location of the device can vary either locally or globally and communication takes place through a wireless, distributed, or diversified network

Mobile Computing

Process of computation on a mobile device

Set of distributed computing systems and servers participate, connect, and synchronize through mobile communication protocols

Technology to wirelessly connect to and use centrally located information and/or application software through small, portable, and wireless computing and communication devices

Pervasive Computing

“Everywhere, everyone, at any time” paradigm

Takes into account the environment in which information and communication technology is used, for example, toys, computers, cars, homes, factories, workareas

Based on integrated processors, sensors, and actuators connected through high-speed networks and combined with new devices for viewing and display

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Page 13: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.2 What is a Mobile Service?

Some Definitions (II)

Ubiquitous Computing

Interconnecting computing devices with environmental objects

Integration of computers into practically all objects in our everyday environment, endowing them with computing abilities

Context-aware Services

Services that automatically adapt their behavior, for example, filtering or presenting information, to one or several parameters reflecting the context of a target person

Context parameter classes: personal, technical, spatial, social, and physical context

Location-based Services

Services that generate, compile, select, or filter information or perform other actions by taking into consideration the locations of one or several target persons or mobile objects

Usually process a target’s current location, her or his last known location, or locations the target has visited in the past, and present the result to the user, either on demand, automatically, or in a continuous fashion.

Location is derived from a process known as positioning, which automatically determines the geographic position of the target in real-time.

13

Page 14: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.2 What is a Mobile Service?

Definition

14

What is a Mobile Service?

Activity of a computer program performed on request for another program, and at least one of them performed on a mobile device

Remotely accessible at well-defined interfaces and offered over a mobile communications system

Invoked and used by protocols of the application layer and possibly supported by enabling functions of the underlying mobile network

Follows one or several of the paradigms of mobile computing, ubiquitous and pervasive computing, and location and context-awareness and combines them with a business model

Page 15: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.2 What is a Mobile Service?

Application Areas and Components

15

Application areas

Paradigms

Mechanisms

3/4G networksAd-Hoc networksWLAN, PAN,…

Mobile phonesSmartphonesBadgesSensors,…

Networks and devices

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g1.3 Mobility Classification

Mobility Concepts for Supporting the Mobile User (I)

16

Terminal Mobility

Refers to the seamless mobility of mobile devices

Requires wireless connection between mobile device and base stations (in case of infrastructure-based networks) or between several mobile devices (in case of ad-hoc communications)

Registration, call, and connection between mobile device and network are kept while in motion

Key functions: wireless communications, handover, location management, roaming

Fixedassignment

Wiredconnection

No mobility support

Fixedassignment Wireless

connection

Terminal mobility

Page 17: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.3 Mobility Classification

Mobility Concepts for Supporting the Mobile User (II)

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Personal Mobility

Means that users can access their services according to their subscription from different devices and device types

User is available via her/his telephone number or email address

User profiles and services are available across device boundaries

Key functions: authentication mechanism

Network A

Network B

Temporaryassignment

Wiredconnection

Personal mobility

Page 18: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.3 Mobility Classification

Mobility Concepts for Supporting the Mobile User (III)

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Service mobility: home-centric service control for roamers

Visited Network

Home Network

Server

Service request

Service response

Client

Service mobility: visited-centric service control for roamers

Visited Network

Home Network

Server

Service request

Service response

Client MobilityControler

Inquiry

Permission

Service Mobility

Enables usage of tailored and personalized services even if the user is roaming to foreign networks

Page 19: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.3 Mobility Classification

Mobility Concepts for Supporting the Mobile User (IV)

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Session Mobility

Allows to interrupt sessions and to resume them later possibly from another terminal or another network

Server

ServerClient

Session mobility between networks

Server

Client

Client

Session mobility between terminals

Page 20: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.3 Mobility Classification

Mobility with regard to the Network Topology

20

Micro Mobility

Mobility support within a radio cell or between different cells, but within a single access network

Mobility management at data link layer

Macro Mobility

Mobility support between different access networks connected to a common core network or within a certain geographic region

Mobility management at network layer

Global Mobility

Mobility support between different core network and/or network operators

Mobility management at network layer and/or at application layer

Locatio

n-u

pd

ate frequ

ency

Dis

tan

ce

Far

High

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g1.4 Protocol Overview

Protocol Stack (I)

21

Radio CorePhysical

Data link

Network

Transport

Application

Physical

Data link

Network

Transport

Application

Physical

Data link

Network

Physical

Data link

Protocol stack: layered architecture of protocols for managing the data exchange between peers (end systems and intermediate systems)

Protocol: set of rules prescribing the format and meaning of messages, frames, and packets exchanged between the peer entities within a layer

Service: set of operations that a layer provides to the next higher layer

End-systems need a full protocol stack comprising all layers

Intermediate systems do not necessarily need all layers

Entities at the same level communicate with each other

Page 22: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.4 Protocol Overview

Protocol Stack (II)

Physical layer

Sender: transformation of a bit stream into signals for transmission

Receiver: transformation of signals into a bit stream

Tasks: frequency selection, generation of carrier frequency, signal detection, modulation of data onto a carrier frequency, and encryption

Data link layer

Point-to-point or point-to-multipoint connection between sender and receiver(s)

Medium access, multiplexing, detection and correction of transmission errors, and detection of data frames (synchronization)

Network Layer

Connection between two entities over many intermediate systems

Routing of packets through a network

Addressing, routing, localization, handover between different networks

Example: Internet Protocol (IP)

22

Radio CorePhysical

Data link

Network

Transport

Application

Physical

Data link

Network

Transport

Application

Physical

Data link

Network

Physical

Data link

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g1.4 Protocol Overview

Protocol Stack (III)

Transport layer

Establishment of an end-to-end connection

Quality-of-service (QoS), flow and congestion control

Example: Transmission Control Protocol (TCP)

Application layer

Protocols designed for fulfilling communication needs of an application

Example: Hypertext Transfer Protocol (HTTP)

23

Radio CorePhysical

Data link

Network

Transport

Application

Physical

Data link

Network

Transport

Application

Physical

Data link

Network

Physical

Data link

What is a gateway? Intermediate system containing peers up to the transport or application layer Used in mobile networks…

… for converting between different application layer protocols… for converting between different transport layer protocols… for improving performance of transport/application layer protocols… for supporting mobility

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g1.5 Physical Layer Overview

The “Wireless Transmission Chain”

Receiving Station

Transmitting Station

Modulation

Source decoding(e.g. speech

processing)

Multiplexing

Channel decoding(Block decoding,

convolutional decoding,

Deinterleaving)

Encryption

Decryption

Channel encoding(Block encoding,

convolutional encoding,

interleaving)

Demultiplexing

Source encoding(e.g. speech

processing)

Demodulation

The “Air Interface”

24

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g1.5 Physical Layer Overview

Signals

Data is transmitted via radio signals in wireless networks

Radio signal: electromagnetic wave…

…generated by a transmitter in dependence on the data to be transferred (modulation*),

…emitted by the antenna of the transmitter,

…caught by the antenna of the receiver, and

…sampled by the receiver to recover the data bits (de-modulation)

Carrier frequency/carrier: radio signal of a constant frequency generated by the receiver for modulation

Carrier frequency can be described by a sine wave (defined by three parameters)

Each parameter can be used for the modulation of data

Amplitude Shift Keying

Frequency Shift Keying

Phase Shift Keying

ttt tfAtg 2sin

Amplitude Frequency Phase

25

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g1.5 Physical Layer Overview

Modulation (I)

Modulation: modification of a carrier’s parameters (amplitude, frequency, phase) according to the pattern provided by another signal

Shift keying: digital modulation, i.e., the modulating signal is a digital signal derived from a sequence of symbols

1 0 0 1 0 1 1 0Data

Carrier

Modulated

signal

Pulses

Phase Shift Keying (PSK)

1 0 0 1 0 1 1 0Data

Carrier

Modulated

signal

Pulses

Frequency Shift Keying (FSK)

1 0 0 1 0 1 1 0Data

Carrier

Modulated

signal

Pulses

Amplitude Shift Keying (ASK)

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Page 27: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.5 Physical Layer Overview

Modulation (II)

Quadrature Amplitude Modulation

(QAM) Combination of ASK and QPSK

Eight signal states → three bits are transmitted in a single step

Used as one alternative for IEEE 802.11

I

Q

000 001

010

100

110

111

011Data 010 101 000 111 011 110 001 100

101

Source: U. Reimers: DVB- The Family of International Standards for Digital Video Broadcasting, Springer-Verlag 27

Page 28: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.5 Physical Layer Overview

Error Sources (I)

Error sources

Because of phenomena like multipath propagation, path loss, and Doppler shift wireless transmission is susceptible to comparatively high error rates

Bit error rates

Bit error rate (BER): probability of any given bit being in error

Wireless links: BER=10-1-10-5

Electrical wired link: BER=10-9

Optical wired link: BER=10-12

Path Loss

Signals attenuate over distance when travelingfrom the transmitting to the receiving antenna

Degree of attenuation is referred to as path loss

Path loss is influenced by

Distance between transmitting andreceiving antenna

Terrain and obstacles in-between

Frequency components of the signals

Isotropic antenna

Distance d

Surface of a sphere

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Page 29: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.5 Physical Layer Overview

Error Sources (II)

Multipath Propagation

Due to reflection, scattering, and diffraction signal reaches the receiver over various paths

Signals traveling along different paths with different lengths arrive at the receiver at different times

Copies of a signals may arrive at different phases - if these phases add destructively, the signal level relative to noise declines

Cumulative signal is smeared or spread (delay spread) and, as a consequence, intersymbol interference occurs

As the mobile antenna moves, the location of various obstacles change, hence the number, magnitude, and timing of the secondary pulse change

Doppler Shift

Change in the frequency of a wave resulting from the relative velocity of a transmitter with respect to a receiver

Frequency increases when moving towards the base station

Frequency decreases when moving away from the base station Moving source29

Page 30: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.6 Data Link Layer Overview

Multiple “Users” of the Air Interface

The “Air Interface”Cellular

networks

Local and personal area networksMilitary

networks

Aviation and seafaring

...

Terrestrial television

Terrestrial

radio

Satellite

communications

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Page 31: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.6 Data Link Layer Overview

Multiplexing (I)

Motivation

Subdivides a communication medium into different channels, each of which to be used for data transmission independent from the other channels

Fixes a communication channel by separation of space, time, frequency, and code or a combination thereof

Communication channel refers to an association of sender(s) and receiver(s) that want to exchange data

Medium Access Control

Dynamically assigns communication channel resulting from multiplexing to users

Analogy

Highways with several lanes

many users: car drivers

medium: highway

interference: accidents

31

Space division multiplex

Time division multiplex

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g1.6 Data Link Layer Overview

Multiplexing (II)

Space Division Multiplexing (SDM)

Separation of channels by mapping each channel onto a dedicated space

Non-overlapping interference ranges

Enabled by sector and directional antennas

Usually used in combination with frequency, time, or code division multiplexing

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k3k2k1 k4 k6k5

s1

ct

fs3

ct

fs6

ct

f

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g1.6 Data Link Layer Overview

Multiplexing (III)

Frequency Division Multiplexing (FDM)

Subdivision of the frequency dimension into several non-overlapping frequency bands, each continuously carrying one channel

Guard spaces between frequency bands to avoid overlapping (adjacent channel interference)

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k3k2k1 k4 k6k5

t

c

f

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g1.6 Data Link Layer Overview

Multiplexing (IV)

Time Division Multiplexing (TDM)

All senders alternately use the same frequency at different points in time

Avoidance of transmission overlaps (co-channel interference) by time gaps (guard spaces)

Requires precise synchronization between senders (either by a precise clock or by a dedicated synchronization signal accessible for all senders)

Flexible, as senders with heavy load can be assigned more sending time and senders with light load less sending time

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k6

c

k5

k4

k3

k2

k1

t

f

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g1.6 Data Link Layer Overview

Multiplexing (V)

FDM and TDM combined

Channel can use a certain frequency band for a certain amount of time

Guard spaces in the time and in the frequency dimension

Robust against small-scale fading by using frequency hopping (fast change of frequency bands)

Deployed in GSM and DECT

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k6

ck5

k4

k3

k2

k1

t

f

Page 36: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.6 Data Link Layer Overview

Multiplexing (VI)

Code Division Multiplexing (CDM)

All channels use the same frequency band at the same time

Separation by codes, guard spaces corresponds to the distance between codes (orthogonal codes)

Good protection against interference and tapping (i.e., signals are spread on a broad frequency band, and interpretation of a signal is only possible with matching code)

High complexity of the receivers

Precise synchronization between sender and receiver

Initially used in military application

Designated multiplexing technique for UMTS/IMT-2000

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c

f

k6

k5

k4

k3

k2

k1

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g1.6 Data Link Layer Overview

Medium Access (I)

Medium Access

Access methods in wireless systems are responsible to coordinate the successful operation of multiple terminals over the wireless medium (air)

Access methods were originally developed for wired media and later on adopted to the wireless medium

Differences in wired and wireless media requires modifications to make access methods suitable for the wireless medium

Main differences of wired and wireless media

Availability of bandwidth

The “air” is shared between all wireless systems and cannot be multiplied by laying additional cables as done in wired transmission

Wireless access methods must cope for the efficient use of the one and only medium “air”

Reliability of transmission

Phenomena like multipath propagation and doppler shift cause high error rates and make wireless transmission less reliable in comparison to wired media

Wireless networks often use different packet sizes and modified access methods to optimize the performance to the specifics of the unreliable wireless medium

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Page 38: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.6 Data Link Layer Overview

Medium Access (II)

Fixed-assignment access

Originates from the telecommunications domain

Make efficient use of communication resources when each user has a steady flow of information to be transmitted (e.g., digitized voice traffic, data file transfer, facsimile transmission)

Access is coordinated by dedicated signaling channels that exchange short messages to obtain resources (e.g., links, switches,...) in the telephone network at the beginning of the conversation and to release resources at the end of the call

Access methods assign a slot of time, a portion of frequency, or a specific code to the user (preferably for the entire length of the conversation)

Random Access

Originates from the data communications domain

Provides a more flexible and efficient way of managing channel access for transmitting short, bursty messages (e.g., Web browsing)

Each packet of the data burst carries some signaling information related to the address of the destination and the source

Provides the user with varying degrees of freedom in gaining access to the network whenever information is to be sent

Randomness of user access may cause contention among the users for access to a channel, resulting in collisions of contenting transmissions

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Page 39: Mobile Services (ST 2010) · s – tion ice g Mobile Services Summer Term 2010 1 Introduction 1.1 The Emergence of Mobile Services 1.2 What is a Mobile Service? 1.3 Mobility Classification

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g1.6 Data Link Layer Overview

Medium Access (III)

Fixed Assignment Methods

Frequency Division Multiple Access (FDMA)

Time Division Multiple Access (TDMA)

FDMA/TDMA

Code Division Multiple Access (CDMA)

Random Assignment Methods

ALOHA

Slotted ALOHA

Carrier Sense Multiple Access (CSMA) - Slotted vs. Unslotted | non-persistent vs. p-persistent

Multiple Access with Collision Avoidance (MACA)

39

For detailedinformation see: