Mobile Communications Wireless Telecommunication

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Mobile Communications

Wireless Telecommunication

Systems

 Generation 1 (1G)  Generation 3 (3G)  Generation 2 (2G)  Generation 2.5 (2.5G)  Generation 4 (4G)  TETRA

Mobile Communication Wireless Telecommunication 1

History

o Mobile Communication: transmission of signals and b t t ti f hi h t l t i bil messages between stations from which at least one is mobile o Goes back to the 1920’s: public wireless radio system

operated by the train in Germany (Reichsbahn)p y y ( )

o 1946 first portable mobile telephone in the US: 18kg, 8min. battery life

1957 fi t bil t l ti t i G

o 1957 first mobile telecommuncation system in Germany (nowadays called PLMTSstands for Public Land Mobile Telecommunications System)so called A-system, manually switched, 137 calling zones

o 1972 start of operation of the B-System, automatic switching, but separate phone number in each calling zone (i.e. one had but separate phone number in each calling zone (i.e. one had to know who is where, if that one is to be called)

History

o 1981 first analog cellular system with fixed number for b ib t ti h d b t ll NMT 450 i subscribers, automatic handover between cells. NMT 450 in Scandinavia. This is sometimes called 1st_{generation (1G)}_.

o 1981 C-Netz in Germany, analog, in operation until 2001y, g, p o 1982 work begins on a standard for a pan-European digital

PLMTS which offers new services (SMS, call forwarding, …) by Group Speciale mobile (GSM)

by Group Speciale mobile (GSM)

o 1987 "Memorandum of Understanding" signed by 18 countries to deploy „GSM“ (now “Global System for Mobile Communication”). In 1988 the standards were taken over by ETSI (European Telecommunication Standards Institute). This is a system of the _y 2nd_{Generation (2G)}₍ ₎

o 1992 first GSM networks in operation 1993 one million subscribers to GSM

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History

o 1998 introduction of GSM 1800

o 1999 Wireless Application Protocol (WAP) o 1999 HSCSD

o 2000 GPRS Generation 2 5 (2 5G) o 2000 GPRS, Generation 2.5 (2.5G)

o 25.9.2002 first operation of a 3rdGeneration (3G) network in Europa (UMTS) in Austria

o 2006 NTT DoCoMo starts 4thGeneration (4G) trial network in in Yokosuka in Japan. Maximum transmission rate 2,5 Gigabit pro Sekunde.

pro Sekunde.

o 2007 4G trial networks with100 Gigabit/s at 10 km/h

o First 4G-Networks on the Basis of LTE (Long Term Evolution) in 2011

Main characteristics of different generations

o Generation 0 (0G): calling zones, no handover o Generation 1 (1G): analog, uniform subscriber

number handover between cells number, handover between cells

o Generation 2 (2G): fully digital o Generation 2.5 (2.5G): data transmission

G ti 3 (3G) b d b d di it l o Generation 3 (3G): broad band digital

o Generation 4 (4G): all IP based, broad band, high o Generation 4 (4G): all IP based, broad band, high

speed

Generation 1 (1G)

o wasn’t the beginning of mobile communication, but the b i i f ll l ith h d d i b t

beginning of cellular with handover and roaming between some network operators

o analog transmission of user channels, mostly for speech onlyg , y p y o already digital signalling for switching purposes

o no dominant standard:

o Nordic Mobile Telephone NMT-450 und NMT-900 o Total Access Communication System (TACS), Japan, GB o Advanced Mobile Phone Services (AMPS) in US

o Advanced Mobile Phone Services (AMPS) in US o C-Netz (Germany)

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Generation 1 (1G)

Example C-Netz (Germany)

o Technical features:

o speech and signalling is transmitted in parallel (in band) o speech and signalling is transmitted in parallel (in band) o speech from 300 to 3400 Hz

o downlink 461,30 to 465,74 MHz o uplink 451,30 to 455,74 MHz o duplex separation10 MHz

o channel separation 20 kHz (222 channels) o transmit power 5mW to 15W

Generation 1 (1G)

cell radius 2km – 20km

cell around base station

switching system

Generation 1 (1G)

o Sender divides speech signal into blocks of 12 5 ms into blocks of 12,5 ms o compression of the blocks

results in extra time slots of 1 1 ms

1,1 ms

o extra time slots are used to transmit signalling information, e.g. handover, …

o Receiver separates signalling data from speech and data from speech and decompresses the signal

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Generation 1 (1G)

o Already in the first generation the smallest part of the transmission path is done wireless is done wireless cellular user air interface core network Hand n t er Handynutzer fixed network core network gateway

Generation 1 (1G)

Generation 2 (2G)

o digital for user traffics and signalling

hi h it id t th 1G

o higher capacity, wider spectrum than 1G o hierarchical cell structure:

Generation 1 (1G)

Generation 2 (2G)

Main standards

o Global System for Mobile Communication (GSM) o Digital AMPS (D-AMPS)g ( )

o IS-95

o Personal Digital Cellular (PDC)

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Generation 2 (2G) - GSM

o Global System for Mobile Communication (GSM) is the most successful cellular system worldwide >80% market share

cellular system worldwide, >80% market share o 1988 first trials of GSM, 1991 first network in operation o 1993 first million

o 1993 first implementations outside Europe (Australia, New Zeeland, Hongkong)

o 2011 approx. 5 million subscribers (pp (http://www.gsmworld.comp g )) o Coverage map (http://www.gsmworld.com/roaming/gsminfo) o Operations in different bands, e.g. 450MHz, 850MHz , 900MHz,

1800MHz 1900MHz 1800MHz, 1900MHz, …

o Roaming contracts between operators result in a single world wide network

Generation 1 (1G)

Generation 2 (2G) - GSM

Coverage by China Mobile

source: GSM Association

Generation 1 (1G)

Coverage by AT&T Mobile

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Coverage by Radiomovil (Mexico)

Generation 1 (1G)

Coverage by E-Plus (Germany)

Generation 1 (1G)

Generation 2 (2G) – GSM – system architecture

VLR HLR fixed network, BSC VLR HLR , BSC (G)MSC Core Network BTS Core Network (CN)

Base Station Subsystem (BSS) = Radio Access Network (RAN)

Generation 1 (1G)

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Generation 2 (2G) – GSM components

Mobile Station

MS

Mobile Station

o max. transmit power is 2-20W

o MS only works with a SIM (Subscriber Identification Module): o MS only works with a SIM (Subscriber Identification Module):

o smart card with memory

o identifies the subscriber in the network o can store personal data such as address book o can be protected by PIN

Generation 1 (1G)

Generation 2 (2G) – GSM components

Base (Transceiver) Station

BTS

Base (Transceiver) Station

o is the “opposite” of the MS o is close to the center of a cell o is close to the center of a cell

Generation 1 (1G)

Generation 2 (2G) – GSM components

Base Station Controller

BSC

Base Station Controller

o supervises several base stations o frequency allocation

o frequency allocation o handover functionality

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Generation 2 (2G) – GSM components

(Gateway) Mobil Switching Center

(G)MSC

(

y)

g

o Interface to the fixed network

o Complete switching system with all necessary routing o Complete switching system with all necessary routing

functionality to switch connections within the system and the outside

Contains all relevant data for each of the subscribers of the o Contains all relevant data for each of the subscribers of the

network that operates this (G)MSC

Generation 1 (1G)

Generation 2 (2G) – GSM components

Home Location Register

o is the “home” of a subscriber (actually the SIM)

HLR

Home Location Register

o s e o e o a subsc be (ac ua y e S ) o contains all relevant data of all subscribers o permanent data, e.g.:

o IMSI (International Mobile Subscriber Identification Number) is not identical with phone number

o shared secrets (keys) o shared secrets (keys)

o information about supplementary services of each subscriber o temporal data, e.g.

o address of the current VLR o destination for call forwarding

Generation 1 (1G)

Generation 2 (2G) – GSM components

Visitor Location Register

o contains all relevant data of a subscriber currently within a MSC

VLR

Visitor Location Register

o co a s a e e a da a o a subsc be cu e y a SC o temporal data are somewhat different from HLR, e.g.

o TMSI (Temporal MSI), use for confidentiality reasons, so that th IMSI d ’t h t t itt d th i i t f

the IMSI doesn’t have to transmitted on the air interface several times

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Generation 2 (2G) – GSM frequency

o 35 MHz bandwidth = 175 x 200 Khz channels (FDMA)

8 h l (TDMA)

o 8 users per channel (TDMA)

880 - 915 Mhz (uplink) 925 - 960 Mhz (downlink) 891,0 Mhz channel 45 891,2 Mhz ... 890,6 Mhz channel 43 890,8 Mhz channel 44 , ...

Generation 1 (1G)

Generation 2 (2G) – GSM TDMA

1710 - 1785 Mhz (uplink)

1805 1880 Mh (d li k)

1805 - 1880 Mhz (downlink)

Generation 1 (1G)

o access to a frequency band is only allowed during certain times (time slots)

certain times (time slots)

o a mobile station may have a slot in a TDMA frame

MS A 6 7 0 1 2 3 4 5 6 7 0 1



MS A TDMA frame 4,615 ms

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Generation 2 (2G) – GSM TDMA

o A mobile station is allocated to the same TDMA time slot for uplink and downlink however uplink and downlink are shifted by 3 slots and downlink, however, uplink and downlink are shifted by 3 slots, advantages:

o no sending and receiving at the same time o less energy consumption

o less cost

Time Division Duplex

0 1 2 3 4 5 6 7 0 1



₂ ₃



_downlink

6 7 0 1 2 3 4 5 6 7 0



₅



_uplink

Generation 1 (1G)

Generation 2 (2G) – GSM TDMA

o energy built up and down at the antenna (data burst)

dB +4 6 -6 -3030 -70 (148 bits) 28 s 542.8 s 28 s

Generation 1 (1G)

structure of a „Normal Burst“ in a time slot:

User Data 57 Bits User Data 57 Bits Training Sequence 26 Bits T 3 T 3 S 1 S 1 GP 8,25 148 Bits = 546.12 s

T (Tail Bits)

S (Signalling/User Data)

( g

g

)

GP (Guard Period)

Generation 1 (1G)

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other bursts: other bursts:

Generation 1 (1G)

Generation 2 (2G) – GSM Hierarchy of frames

Generation 1 (1G)

Generation 2 (2G) – GSM Physical vs. Logical channels

o Physical channels are formed by all the available time slots in a BTS If the BTS uses 6 frequency bands (carriers) the there are BTS. If the BTS uses 6 frequency bands (carriers), the there are 48 physical channels.

o The logical channels are a structure on top of the physical ones. One physical channel may carry several logical channels. Each logical channel performs a specific task

Logical channels: Logical channels:

o Speech traffic channels (TCH) o Full-rate TCH (TCH/F) o Half-rate TCH (TCH/H) o Broadcast channels (BCH)

Frequency correction channel (FCCH) o Frequency correction channel (FCCH) o Synchronization channel (SCH)

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Generation 2 (2G) – GSM Physical vs. Logical channels

Logical channels (cont.):

C ll b d t h l (CBCH) o Cell broadcast channel (CBCH) o Common control channels (CCCH)

o Paging channel (PCH) o Paging channel (PCH) o Access grant channel (AGCH) o Random access channel (RACH) o Dedicated control channel (DCCH)

o Slow associated control channel (SACCH) Stand alone dedicated control channel (SDCCH) o Stand-alone dedicated control channel (SDCCH) o Fast associated control channel (FACCH)

Generation 1 (1G)

Generation 2 (2G) – GSM Synchronization

Synchronization of an MS with a network (procedure lasts 2-20 sec)

BTS FDMA i ( l t 200kH b d)

o BTS uses an FDMA carrier (one complete 200kHz band) as a base channel

o On this channel the BTS transmits with maximum power, i.e. p every single time slot in a frame is filled, most of them with a dummy burst

o The MS looks for a FCCH on this base channel o The MS looks for a FCCH on this base channel

o If the FCCH has been found the MS can synchronise on

frequency and time and look for the BCCH in the same frequency band.

o BCCH contains information, e.g. for describing the current control channel structure and other information about the network and channel structure and other information about the network and how to gain access

Generation 1 (1G)

Generation 2 (2G) – GSM Location update

MS BTS BSC MSC VLR HLR Channel request MS BTS BSC MSC VLR HLR Channel activation command Channel Activation k l d acknowledge Channel assignment Location update request Location update request Authentication request

Authentication responsep

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Generation 2 (2G) – GSM Location update (cont.)

MS BTS BSC MSC VLR HLR

Comparison of

Authentication parametersp

Assignment of the new area and the TMSI Acknowledgement of the new area and the TMSI

E t f th d

Entry of the new area and TMSI into VLR and HLR Channel release

Channel release

Generation 1 (1G)

Generation 2 (2G) – GSM MOC

Mobil-Originating-Call (MOC) Channel request MS BTS Channel request Channel assignment Call establishment request A th ti ti t Authentication request Authentication response Ciphering command

Ciphering complete (now ciphering) Setup message, indicating the desired number

Call proceeding, the network routes the call to the desired number

Generation 1 (1G)

Generation 2 (2G) – GSM MOC (cont.)

Mobil-Originating-Call (MOC)

MS BTS

Assignment of a traffic channel for the Assignment of a traffic channel for the user data

Assignment complete, from now on all messages are exchanged on traffic channel messages are exchanged on traffic channel Alerting, the called number is not busy and the phone is ringing

Connect the called party accepted the call Connect, the called party accepted the call Connect acknowledge, now the call is active and both parties can talk to each other Exchange of speech data

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Generation 2 (2G) – GSM Handover

o If an MS in operation moves from one cell to another, a handover procedure takes place

procedure takes place

o The BTS tells the MS on the base channel a list of channels of neighbouring cells

o The MS constantly measures the signal levels for these channels of neighbouring base stations

o The signal levels of the own cell and those of the neighbouring o The signal levels of the own cell and those of the neighbouring

cells are reported back by the MS to the own BTS

o If handover is necessary, i.e. the signal quality of a neighbouring cell is significantly better than the own one, handover will be performed

Generation 1 (1G)

Generation 2 (2G) – GSM Handover (cont.)

receive level BTSold receive level BTSnew HO_MARGIN MS MS BTS_old BTS_new

Generation 1 (1G)

Generation 2 (2G) – GSM Handover (cont.)

Types of handover MS MS MS MS 1 2 3 4 MS MS MS MS BTS BTS BTS BTS MSC MSC BSC BSC BSC 1 – Intra-Cell 2 – Inter-Cell 3 – Inter-BSC 3 Inter BSC 4 – Inter-MSC Generation 1 (1G)

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Generation 2 (2G) – GSM Handover (cont.)

Handover procedure BTS BSC MSC BSC MS BTSold BSCnew BTS measurement result BSCold MSC MS measurement report HO decision BTSnew HO decision HO required _{HO request} resource allocation HO access ch. activation ch. activation ack HO request ack HO command HO command HO command HO access Link establishment HO complete HO complete clear command clear command clear command

clear complete _{clear complete}

Generation 1 (1G)

Generation 2 (2G) – GSM Services

o GSM offers three service domains

B S i

o Bearer Services o Telematic Services o Supplementary Services o Supplementary Services

Generation 1 (1G)

Generation 2 (2G) – GSM Bearer Services

o Telecommunication services to transfer data between access points S ifi ti f i t th t i l i t f (OSI l 1 3) o Specification of services up to the terminal interface (OSI layers 1-3) o Different data rates for voice and data (original standard)

o data service (circuit switched) o data service (circuit switched)

o synchronous: 2.4, 4.8 or 9.6 kbit/s o asynchronous: 300 - 1200 bit/s o data service (packet switched)

o synchronous: 2.4, 4.8 or 9.6 kbit/s asynchronous: 300 9600 bit/s o asynchronous: 300 - 9600 bit/s

o In 2.5G much higher data rates are possible, will be covered later o In 2.5G much higher data rates are possible, will be covered later

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Generation 2 (2G) – GSM Tele Services

o Telecommunication services that enable voice communication via mobile phones

mobile phones

o All these basic services have to obey cellular functions, security measurements etc.

o Offered services o mobile telephony

primary goal of GSM was to enable mobile telephony offering the primary goal of GSM was to enable mobile telephony offering the traditional bandwidth of 3.1 kHz

o Emergency number

common number throughout Europe (112); mandatory for all service providers; free of charge; connection with the highest priority (preemption of other connections possible)

o SMS (Short Message Service), alphanumerical short messages for the display at the receiver mobile phone

Generation 1 (1G)

Generation 2 (2G) – GSM Supplementary Services

o Services in addition to the basic services, cannot be offered stand-alone

alone

o Similar to ISDN services besides lower bandwidth due to the radio link

o May differ between different service providers, countries and protocol versions

o Important services: o Important services:

o identification: forwarding of caller number o suppression of number forwardingg o automatic call-back

o conferencing with up to 7 participants

o locking of the mobile terminal (incoming or outgoing calls) o ...

Generation 1 (1G)

Generation 2 (2G) – Other standards

o IS-95 (CDMAone): a North American standard of 2G that already uses DS CDMA on the Air interface Couldn’t gain much territory uses DS-CDMA on the Air interface. Couldn t gain much territory against GSM/UMTS and also it’s follow-up CDMA2000.

o Personal Digital Cellular (PDC) o Japanese Standard

Based on TDMA o Based on TDMA o 800 and 1500 MHz

o Physical characteristics similar to D-AMPS (the follow up of the o Physical characteristics similar to D AMPS (the follow up of the

North American AMPS standard) o Not successful outside Japan

o Japan was one of the prime pusher of 3G (UMTS)