Multicast in Third-Generation Mobile Networks: Services, Mechanisms and Performance - Rilegato

Rmmler, Robert; Gluhak, Alexander Daniel; Aghvami, A. Hamid

Rilegato

ISBN 10: 0470723262 ISBN 13: 9780470723265

Casa editrice: John Wiley & Sons Inc, 2009

Riassunto

A hands-on tutorial on multicast in third-generation networks!

In this book, the authors describe how to perform multicast, the one-to-many delivery of data to a group of destinations, in third-generation mobile networks.

The authors provide an overview of the services that can be realized with multicast in third-generation networks, describe the mechanisms required to support these services and highlight the performance of several multicast mechanisms. The focus of this book is on multicast in UMTS and CDMA2000 networks, the dominant third-generation network standards. In addition to describing the standards for multicast, the authors also provide extensive performance results of multicast in third-generation networks.

Key Features:

•Provides an in-depth review of the fundamentals of multicast

•Describes in detail the MBMS and BCMCS standards for multicast in UMTS and CDMA2000 networks, respectively

•Provides a comprehensive overview of the services that can be realized with multicast in third-generation networks

•Highlights the performance of multicast in third-generation networks

•Investigates how multicast can be achieved in heterogeneous networks consisting of cellular and broadcast networks

This book is an invaluable resource for professional engineers and researchers working in the area of third-generation networks. Postgraduate and graduate students on networking and communications courses will also find this book an insightful and valuable reference.

Su questo libro

Informazioni sull?autore

Robert Ruemmler currently works for Accenture AG, Switzerland as a consultant for leading Swiss banks. Robert holds a PhD from King's College London, United Kingdom (2005, Thesis: On the Distribution of Software to End-User Terminals in Third-Generation Mobile Networks). His research interests include Multicast in third-generation networks, IP multicast, software download to the mobile terminals, and software-defined radio. He has been actively collaborating with leading companies in mobile communications industry as part of European Commission-sponsored research projects.

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Multicast in Third-Generation Mobile Networks

Services, Mechanisms and PerformanceBy Robert Rmmler Alexander Daniel Gluhak A. Hamid Aghvami

John Wiley & Sons

Copyright © 2009 John Wiley & Sons, Ltd
All right reserved.
ISBN: 978-0-470-72326-5

Chapter One

Introduction

This book focuses on the deployment of multicast in third-generation networks. Multicast is the efficient delivery of data to a group of destinations simultaneously. With multicast, messages are delivered as much as possible only once over each link of the network, creating copies only when the links to the destinations split.

In this chapter, we firstly provide an introduction to cellular mobile communication systems, in particular with respect to the features that distinguish the different generations of mobile communication systems, from analog first-generation to the fourth-generation systems currently in development. Then, we describe several fundamental aspects of data networking that are relevant for multicast. This is followed by an overview of how multicast can be achieved in data networks. We then introduce the basics of Internet Protocol (IP) multicast, the standard for multicast in internetworks. A more detailed description of IP multicast is provided in Chapter 2. Finally, we describe several existing mechanisms for carrying out multicast in third-generation networks. Several of these multicast mechanisms are described in much more detail in later chapters.

1.1 Cellular Mobile Communication Systems

The mobile communications industry is a relatively young industry. The basic technological concept of the industry lies in using radio waves to transmit data and connect users. Radio is the transmission of signals by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space. Information is carried by systematically changing or modulating some property of the radiated waves, such as amplitude, frequency or phase. When radio waves pass an electrical conductor, the oscillating fields induce an alternating current in the conductor. This can be detected and transformed into sound or other signals that carry information.

The concept of using radio waves for communication dates back to the second half of the nineteenth century, when the German scientist Heinrich Rudolf Hertz demonstrated in 1888 that an electric spark of sufficient intensity at the emitting end could be captured by an appropriately designed receiver and induce action at a distance. This proved for the first time that electromagnetic waves propagate through the air and have the same properties as light. His English forerunner James Clark Maxwell had foreseen this a few years earlier in 1864. Maxwell's theory of electromagnetic fields claimed the existence of electromagnetic waves and presented four mathematical formulae known today as Maxwell's equations, a set of fundamental equations governing electromagnetism.

Nikola Tesla first demonstrated the feasibility of wireless communications in 1893. He holds the US patent for the invention of the radio, defined as the wireless transmission of data. Guglielmo Marconi demonstrated the use of radio for wireless communications by equipping ships with life-saving wireless communications and by establishing the first commercial transatlantic radio service in 1907. Today, the use of radio takes many forms, including wireless and mobile communication of all types, as well as radio broadcasting.

1.1.1 The Cellular Concept

The design objective of early mobile communication systems was to achieve a large coverage area by using a single, high-power transmitter with an antenna mounted on a tall tower, transmitting on a single frequency. While this approach achieved very good coverage, it also meant that it was impossible to reuse the same frequency throughout the system, since any attempts to achieve frequency reuse would result in interference.

The cellular concept was a major breakthrough in solving the problem of spectral congestion and user capacity. It offered very high capacity with limited spectrum without any major technological changes. The cellular concept is a system-level idea that calls for replacing a single, high-power transmitter with many low-power transmitters, each providing coverage to only a small portion of the service area, referred to as a cell. Each base station is allocated a portion of the total number of channels available to the entire system, and nearby base stations are assigned different groups of channels so that all the available channels are assigned to a relatively small number of neighbouring base stations.

The mobile transceivers (also referred to as mobile phones, mobile stations, mobile terminals, handsets or devices) exchange radio signals with any number of base stations. Mobile phones are not attached to a particular base station, but may make use of any one of the base stations provided by the company that operates the corresponding network. The ensemble of base stations covers the landscape in such a way that the user can travel around and carry on a phone call without interruption, possibly making use of more than one base station. The procedure of changing a base station at cell boundaries is called handover.

Communication from the Mobile Station (MS) to the Base Station (BS) takes place on the uplink channel or reverse link, and from BS to MS on the downlink channel or forward link. To sustain a bidirectional commmunication between a mobile terminal and a base station, transmission resources must be provided both in the uplink and downlink directions. This can happen either through Frequency-Division Duplex (FDD), whereby uplink and downlink channels are assigned on separate frequencies, or through Time-Division Duplex (TDD), where uplink and downlink transmissions occur on the same frequency, but alternate in time.

FDD is efficient in the case of symmetric traffic. Also, FDD makes radio planning easier and more efficient, since base stations do not interfere with each other as they transmit and receive in different sub-bands. TDD has a strong advantage in the case where the asymmetry of the uplink and downlink data speed is variable. As the amount of uplink data increases, more bandwidth can dynamically be allocated to that, and as it shrinks it can be taken away. Another advantage is that the uplink and downlink radio paths are likely to be very similar in the case of a slow-moving system.

1.1.2 Propagation Impairments in Cellular Systems

The design of cellular systems is particularly challenging because of the adverse propagation conditions of the radio channel. Three main propagation impairments are usually distinguished. These are pathloss, slow fading or shadowing and fast fading or multipath fading (Brand and Aghvami, 2002).

The pathloss describes the average signal attenuation as a function of the distance between transmitter and receiver, which includes the free-space attenuation as one component, but also other factors come into play in cellular communications, resulting in an environment-dependent pathloss behaviour. Shadowing or slow fading describes slow signal fluctuations, which are typically caused by large structures, such as big buildings, obstructing the propagation paths. Fast or multipath fading is caused by the fact that signals propagate from transmitter to receiver through multiple paths, which can add at the receiver constructively or destructively, depending on the relative signal phases. The received signal is said to be in a deep fade when the paths add destructively such that the received signal level is close to zero. Fades occur roughly once every half-wavelength (Steele and Hanzo, 1999). With wavelengths of 30 cm and less in cellular communication systems, it is clear that multipath fading can result in relatively fast signal fluctuations (Brand and Aghvami, 2002).

1.1.3 Multiple-Access Schemes

Multiple-access schemes allow several devices connected to the same physical medium to transmit over it and to share its capacity. A multiple-access scheme is based on a multiplex method that allows several data streams or signals to share the same communication channel or physical media. Multiplexing is a term used to refer to a process where multiple data streams are combined into one signal over a shared medium. The resources that may be allocated with a multiple-access scheme are frequency bands, time slots, sets of codes or any combination of the three. The basic multiple-access schemes are Frequency-Division Multiple Access (FDMA), Time-Division Multiple Access (TDMA) and Code-Division Multiple Access (CDMA).

In FDMA, each communication is carried over one or two (depending on the duplexing method) narrowband frequency channels. The channel bandwidth and the modulation scheme determine the gross bit rate that can be sustained. With non-ideal filters, guard bands must be introduced between the FDMA channels to avoid so-called adjacent channel interference.

In TDMA, rather than assigning each user a channel with its own frequency, users share a channel of a wider bandwith in the time domain. This is achieved by introducing a framing structure, with each TDMA frame subdivided into a number of slots equal to the number of users that are to be supported. Provided that enough spectrum is available, multiple carriers may be assigned to each cell. Therefore, such TDMA systems typically feature also an FDMA element and are thus in reality hybrid TDMA/FDMA systems (Brand and Aghvami, 2002). TDMA systems must carefully synchronize the transmission times of all the users to ensure that they are received in the correct slot and do not cause interference.

In CDMA, narrowband signals are transformed through spectrum spreading into signals with a wider bandwidth. As in TDMA, multiple users share the carrier bandwidth, but, as in FDMA, they transmit continuously during the connection. The multiple-access capability derives from the use of different spreading codes for individual users. Because of the spreading of the spectrum, CDMA systems are also referred to as spread-spectrum multiple-access systems. Two basic CDMA techniques suitable for mobile communications are distinguished, namely Frequency-Hopping (FH) and Direct-Sequence (DS) CDMA techniques.

In an FH-CDMA system, a transmitter hops between available frequencies according to a specified algorithm, which can be either random or preplanned. The transmitter operates in synchronization with a receiver, which remains tuned to the same centre frequency as the transmitter. A short burst of data is transmitted on a narrowband carrier. Then, the transmitter tunes to another frequency and transmits again. Thus, the receiver is capable of hopping its frequency over a given bandwidth several times a second, transmitting on one frequency for a certain period of time, then hopping to another frequency and transmitting again. Frequency hopping requires a much wider bandwidth than is needed to transmit the same information using only one carrier frequency.

In a DS-CDMA system, a bit stream is multiplied by a direct sequence or spreading code composed of individual chips. They have a much shorter duration than the bits of the user bit stream, and this is why the original signal's spectrum is spread. The bandwidth expansion factor or spreading factor that results from using a transmission bandwidth that is several orders of magnitude greater than the minimum required signal bandwidth is equal to the duration of a bit divided by the duration of a chip.

1.1.4 First- and Second-Generation Systems

Various first-generation cellular mobile communication systems were introduced in the late 1970s and early 1980s. These early systems were characterized by analog (frequency modulation) voice transmission and limited flexibility. The first such system, the Advanced Mobile Phone System (AMPS), was introduced in the US in the late 1970s. Other first-generation systems include the Nordic Mobile Telephone (NMT) and the Total Access Communication System (TACS). The former was introduced in 1981 in Sweden, then soon afterwards in other Scandinavian countries, followed by the Netherlands, Switzerland and a large number of Central and Eastern European countries. The latter was deployed from 1985 in Ireland, Italy, Spain and the UK (Brand and Aghvami, 2002).

While these systems offered reasonably good voice quality, they provided limited spectral efficiency. They also suffered from the fact that network control messages - for handover or power control, for example - are carried over the voice channel in such a way that they interrupt speech transmission and produce audible clicks, which limits the network control capacity (Goodman, 1990).

The breakthrough of mobile telephony into the mass market occurred only in the 1990s with the advent of digital technology and the introduction of second-generation systems. Capacity increase was one of the main motivations for introducing second-generation systems. With digital technology it became possible to increase capacity by relying on low-bit-rate speech codecs and also integrating voice and data. Also, security was improved, both by means of encryption to provide privacy and authentication to prevent unauthorized access and use of the system. Dedicated channels were used for the exchange of network control information between mobile terminals and the network infrastructure during a call in order to overcome the limitation in network control of first-generation systems.

The Global System for Mobile Communications (GSM) is currently the uncontested standard for second-generation digital cellular communications. GSM, a TDMA-based system with optional slow frequency hopping, has a footprint covering virtually every angle of the world. With a subscriber number close to 500 million and a share of the digital cellular market close to 70 % in early 2001 (Brand and Aghvami, 2002), GSM is truly the global system for mobile communications. The General Packet Radio Service (GPRS) is a best-effort packet-switched service, which was designed as an enhancement to existing GSM networks in order to support non-real-time packet data traffic.

In the US, there are essentially two types of second-generation cellular system that are incompatible with each other. The first is a TDMA system called North American Digital Cellular or Digital AMPS (D-AMPS) and referred to as TDMA. The second system, which was launched later, is cdmaOne, the first operational CDMA system (Goodman, 1990). The relevant air interface specifications are the so-called interim standards IS-136 (for D-AMPS) and IS-95 (for cdmaOne).

The first and most popular Japanese second-generation standard is Personal Digital Cellular (PDC). It was later complemented by the Personal Handphone System (PHS), a mixture between mobile and cordless systems, which caters for low mobility, but is popular for certain applications owing to its relatively high data rates of up to 64 kilobits per second (kbps). Both standards are TDMA-based and have not seen wide deployment outside Japan (Brand and Aghvami, 2002).

1.1.5 Third-Generation Systems

Third-generation mobile networks represent the latest phase in the evolution of cellular technology, following from the first-generation analog and second-generation digital systems. Third-generation systems represent a shift from voice-centric services to converged services, including voice, data, video and so forth. In order to allow for advanced services and applications, third-generation networks provide higher capacity and enhanced network functionality.

Already before the launch of second-generation systems, the research community started to think about requirements for a new, third generation of mobile communication systems and about possible technological solutions to meet them. The European Telecommunication Standards Institute (ETSI) was one of the major players regarding the standardization of third-generation systems. It called its third-generation representative Universal Mobile Telecommunications System (UMTS) and established a number of requirements, according to which such a system should be designed.

The International Telecommunications Union (ITU) initially had the intention of controlling the standardization process such that a single system would emerge. With several bodies submitting their proposals for third-generation systems to the ITU in 1998, it soon became clear that the ITU would not be in a position to enforce a unified system. As a result of this, the ITU then advocated the concept of a family of systems, defined as a federation of systems referred to as International Mobile Telecommunications 2000 (IMT-2000). Eventually, two main camps formed. The first one is united in the Third-Generation Partnership Project (3GPP), dealing with the standardization of UMTS and the evolution of GSM, and the second one in a similar structure, the Third-Generation Partnership Project 2 (3GPP2), dealing with CDMA2000, an evolution of cdmaOne. The following sections provide a brief overview of third-generation systems.

(Continues...)

Excerpted from Multicast in Third-Generation Mobile Networksby Robert Rmmler Alexander Daniel Gluhak A. Hamid Aghvami Copyright © 2009 by John Wiley & Sons, Ltd. Excerpted by permission.
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Dettagli dell'edizione

• Editore: John Wiley & Sons Inc
• Data di pubblicazione: 2009
• Lingua: Inglese
• ISBN 10: 0470723262
• ISBN 13: 9780470723265
• Rilegatura: Copertina rigida
• Numero di pagine: 267
• Contatto del produttore: non disponibile
• Persona responsabile: non disponibile