UMTS, WLAN and new Broadband Technologies. Standards and Technical Basics. Dr. Dietmar Dengler DFKI GmbH, UMTS-Doit

Transcription

1 UMTS, WLAN and new Broadband Technologies Standards and Technical Basics Dr. Dietmar Dengler DFKI GmbH, UMTS-Doit

2 Standardisation ITU (International Telecommunication Union) defines concepts for IMT-2000 (International Mobile Telecommunications at 2000 MHz) Requirements Combination of proposals of different regional standardazation boards IMT-2000 is a family of compatible systems (e.g. wrt. roaming) Multimode devices will have access to all systems two groups have been built Quelle: TKN TU Berlin, Cornelia Kappler Course UMTS Networks

3 UMTS standardization in 3GPP every member company sends delegates to the organization standardization process: standard is what all delegates agree about delegates represent their companies interests standardization is organized by mailing lists and at least 6 meetings per year standardization topics get a defined end point in order to manage the process nearly every year a new release of the UMTS standard is published first UMTS Release is "R99", then Rel4, Rel5,... all specifications are available to the public (as opposed to GSM)

4 Standardization in IETF - Internet Engineering Task Force e.g. IP, TCP, etc. informal organisation of independent engineers and researchers every person can participate on the standardization process influence is based on technical knowledge, reputation, etc. standardization according to: We believe in running code and rough consensus only the things which are implemented can be standardized standardization is organized by mailing lists and at least 3 meetings per year standardization topics are dependent upon the interests of the persons involved for every topic a special working group all documents are available to the public

5 3GPP - IETF cooperation 3GPP and IETF are based on different principles 3GPP defines a complete system (-> cathedral) IETF works on a protocol one by one (-> bazaar) but since telecommunication and internet interact more and more, they have to cooperate but IETF does not produce standards on demand 3GPP cannot wait on standards until someone is interested on it and is happy about a specific solution so, the same people are active in both organizations

6 History of mobile telecommunications 1958 A-Net in Germany: analog, connection initialized by mobile station, switched by hand, no handover, 1971: User 1972 B-Net in Germany : analog, no handover, connection could also be initialized from conventional telephone network if the user location has been known, User 1982 Start of GSM-Specification 1986 C-Netz (1G) in Germany: analog cellular, handover, automatic localization of mobile station 1992 Start of GSM (2G): D1 and D2, completely digital, Roaming, data services possible 1994 E-Net in Germany: E-Plus, Viag Interkom 1998 specification of GSM-successor: UMTS as a european proposal for IMT GSM extension (2.5G): HSCSD, GPRS 2002 Start of UMTS (3G) in test areas 2005 Start of HSDPA (3,5G) in test areas

7 The different generations 1. Generation (analog) Hicap J-TACS C-Netz NMT TACS AMPS speech 2. Generation (digital) PDC GSM D-AMPS «TDMA», IS-136 IS-95 A «CDMA» GSM: speech, SMS, Fax circuit-switched data transmission 9,6 kbit/s 2.5 Generation (packet data) PDC/PDC-P GSM/GPRS IS-95 B GSM/GPRS: new to GSM: packetswitched data transmission up to 80 kbit/s 3. Generation (Multimedia) UMTS UWC-136HS EDGE (GPRS) IMT-2000: System family cdma2000 UMTS: speech Multimedia services high-speed data 384 kbit/s (2 Mbit/s peakrate) Quelle: T-Mobile, Bonn

8 Essential Features of UMTS (Release 99) completely new radio access technology WCDMA (and TD-CDMA) Core-Network (Vermittlungsnetz) is an evolution of the GSM/GPRS-Core-Network UMTS-GSM Interworking: Roaming and Handover/Cell-Reselection of CS- and PS-services in both directions higher bitrates: up to 384 Kb/s compared to 9,6 Kb/s in GSM, and ca. 54 Kb/s in GPRS new Multimedia- and Multitasking abilities extended network security usage of ATM in the Radio Access Network and for the connection of the RNCs to CN

9 UMTS (frequency band) FDD uplink paired spectrum FDD downlink paired spectrum GSM 1900 MHz 1950 MHz 2000 MHz 2050 MHz 2100 MHz 2150 MHz 2200 MHz DECT IMT2000 satellite component unpaired spectrum IMT2000 satellite component paired spectrum paired spectrum unpaired spectrum 850 MHz 900 MHz 950 MHz 1000 MHz 1050 MHz 1100 MHz 1150 MHz 12 packets of 2 x 5 MHz FDD, 5 packets of 1 x 5 MHz TDD TDD FDD TDD uplink FDD downlink UMTS Quelle: T-Mobile, Bonn

10 Architecture of the UMTS-Network

11 Architecture of the UMTS-Network Air interface between UE (User Equipment) and Node B of a cell Node B is physical unit for radio transmission/reception contains signal processing units for channel coding, modulation, etc. Node B s are connected to RNC (Radio network Controller): management unit for a set of cells, handover control, ciphering, etc.; connects to CN CN (Core Network) divided in circuit switched and packet switched domains connection to external networks mobility management by VLR (Visitor Location Register) and HLR (Home Location Register) packet oriented data (PS-Packet Switched) are processed by SGSN (Serving GPRS Support Node) and GGSN (Gateway GPRS Support Node)

12 UTRAN - UMTS Terrestrial Radio Access Network Makro diversity! Quelle: UMTSlink.at

13 Advantages of Softhandover less sensitivity against shadowing effects, e.g. by buildings less sensitivity against multipath effects, e.g. fading (destructive overlap of waves) less frequent service loss on cell change as opposed to hard handover (GSM) less signal to noise ratio: usage of different radio paths decreases the probability of interferences of the same kind

14 Multiple Access Mode Frequency Division Multiple Access FDMA "$% #% Time Division Multiple Access TDMA "#$ % CDMA Code Division Multiple Access $ # Finnisch $ # " $ # " Arabisch Englisch Chinesisch Quelle: T-Mobile, Bonn

15 UMTS Air Interface Two modes: FDD (Frequency Division Duplex) and TDD (Time Division Duplex) FDD uses different frequencies in the paired spectrum for Uplink and Downlink TDD uses same frequency in unpaired spectrum for Uplink and Downlink FDD-Mode Frequency band: Uplink MHz, Downlink MHz Multiple access mode: WCDMA (Wideband Code Division Multiple Access) Bandwidth of a channel: ca. 5 MHz TDD-Mode Frequency band: MHz and MHz Multiple access mode: TD-CDMA (Time Division - Code Division Multiple Access) UMTS started with FDD. TDD maybe later.

16 ' & ( & User k 1 Time Slot = 0,577 ms Quelle: T-Mobile, Bonn

17 CDMA-Principle (UMTS W-CDMA FDD)! " # & Quelle: T-Mobile, Bonn

18 Distinction UMTS FDD vs. TDD Quelle: Vorl.Mobile CommunicationsII, LMU München, A. Küpper

19 Realization of CDMA process by Direct Sequence CDMA-Technique Multiplication of data stream (Bits) with a user-specific two-valued code sequence (Chips) every Bit is therefore mapped on a specific number of chips: Bit stream -> Chip stream sending the signals with a high bandwidth compared to the initial datarate impressing of a fingerprint -> Spreading code Spreading factor = broadening factor of the spectrum = number of chips per bit transmission of all user signals using the same carrier frequency Internal change of bit patterns into NRZ- Signals (No Return to Zero) Bit 1 -> Symbol -1 Bit 0 -> Symbol +1 coded datarate of 3,84Mchip/s

20 Sample Coding (-1) * (+1) = "-1" Quelle: UMTSlink.at

21 Spreading process Spreading code ~ channelisation code

22 Transmission Principle of CDMA Transmitter Receiver (1) Signal Spreader (3) RF Modulator RF Signal Demodulator (3) Spreader (5) p (2) (2) Spreading code p (4) (4)=(2) Despreading code p B in f (1) Input signal (3) TX spread signal Spreading Factor (SF) = B s /B in = R chip /R in R chip : Chip Rate B S R in : Bit Rate des Input-Signals Beispiel: R chip = 3,84 Mcps, R in = 30 kbps, SF=128 f (5) Input signal (detected)l f Quelle: T-Mobile, Bonn

23 Orthogonal variable spreading factor (OVSF) code W-CDMA uses OVSF-codes for spreading every code on a branch of the code tree is orthogonal to every code on another branch codes on the same branch are not orthogonal W-CDMA uses SF 4 to 512 for DL, and 4 to 256 for UL datarate per user can be quickly adapted -> new code with other SF UMTS FDD: adaptation possible every 10ms SF =

24 Process Gain Code length responsible for process gain decoding is always done over the complete chip length scalar product during decoding provides the amplified values +/-SF SF corresponds with process gain the longer the code the bigger the band spreading and the process gain that means for a CDMA-system: the transmission of signals with higher SF and therefore lower datarate needs less power on the antenna as signals with high datarate if the radio reception on the UE is bad and the transmitter power can no more be increased then the reduction of the datarate by a higher SF provides an amplification of the signal, i.e. the failure ratio decreases a dynamic process providing more fail-safe communication

25 Disadvantage of orthogonal Channelization codes Sample assumption for uplink: signal delay at Node B = 1 Chip Fatal: initially orthogonal codes are recognized as identical codes Downlink problem: if all cells are using the same codetree then failures arise at the borders of the cells

26 Scrambling codes provide a solution Scrambling codes are only used for an orthogonal coding of the cells in DL and of the Ues in UL instead of a usage as a means of spreading the length is fixed at chips, exactly the length of a signal time frame (10ms) every time frame is coded by multiplication with the scrambling code scrambling codes persist their orthogonality also in the asynchronous case cell network planning distributes the codes to the Node Bs RNC sends info to UE to enable it to generate an uplink-scrambling code

27 AMR (adaptive multirate) speech transmission Basic idea: dynamic optimization of the relationship of speech coding to channel coding (protection against failures) the transcoders are a set of speech codecs at their disposal (AMR 4,75kb/s to AMR 12,2kb/s) adaptation of the codec to the current interference situation (for each UE individually) if the datarate decreases then the process gain increases and also the coverage of the UE increases (transmitting power decreases which leads to a reduction of interference)

28 Security in the UMTS network Maintaining the security concepts of GSM usage of SIM-Card authentification of SIM against the net encryption of the data on the air interface Enhanced security of UMTS mutual authentification of USIM (Universal Subscriber Identity Module) and net livetime of temporary keys limited increasing key length from 64 bit to 128 bit ciphering on the air interface and between Node B and RNC Compatibility of 3G/2G security features: usuage of USIM for GSM access Ciphering / Integrity Check Network Authentication USIM Authentication USIM Node B RNC MSC / SGSN HLR Quelle: T-Mobile, Bonn

29 Mobile and wireless services Always Best Connected Integration of heterogenous fixed and wireless networks with highly different characteristics Vertical Handover widearea networks metropolitan networks campus networks Horizontal Handover buildings Quelle: Vorl. Mobilkommunikation, J. Schiller, FU Berlin

30 Mobility with WLAN & UMTS UMTS provides cost-efficient broadband wide area access UMTS supports international roaming UMTS provides integrated accounting UMTS provides secure network access WLAN provides wireless high-speed access to existing networks with limited mobility in the area of hot spots WLAN and UMTS complement each other and will coexist!

31 Wireless Evolution Quelle: Farpoint Group

32 Wireless Evolution Quelle: Farpoint Group

33 IEEE Standards and working groups Quelle: Vorl. Mobilkommunikation, J. Schiller, FU Berlin

34 Comparison of infrastructure and ad hoc networks Quelle: Vorl. Mobilkommunikation, J. Schiller, FU Berlin

35 Architecture Infrastructure network )' * $ + )+ * $ & $ )$ * & $, $ $, )! -!. * $ Quelle: Vorl. Mobilkommunikation, J. Schiller, FU Berlin

36 Architecture Ad hoc network direct way of communication with restricted coverage Station (STA): device with access to the wireless medium Basic Service Set (BSS): group of stations using the same frequency channel different BSSs can be built by space multiplexing or by using different carrier frequencies Quelle: Vorl. Mobilkommunikation, J. Schiller, FU Berlin

37 WLAN usage in the 2,4GHz band no license required for this band, everyone can use it no regulation of the frequencies public service -> no protection against tapping Internationally regulated! no manipulation on the transmitter only licensed antenna other usage of the band micro wave, bluetooth, radar, motion sensors, wireless headphones, etc. responsibility: RegTP, ETSI (Europe), ITU (international)

38 WLAN coverage b Quelle: F. Jondral, Uni Karlsruhe, Inst. Für Nachrichtentechnik

39 WLAN - Physical Layer DSSS DSSS (Direct Sequence Spread Spectrum) process the standard for b WaveLan 1, 2, 5.5 and 11 MBit new devices backwards compatible bad radio reception involves switching to lower bitrate 13 channels (Europe). USA: 11 channels Raster 5 MHz DSSS Signal is spreaded by Chipping Codes to 22 MHz max. 3 non-overlapping channels WLAN - Control Layer application of specific collision avoidance algorithms AP has control on access to the transmitting medium

40 WLAN channel allocation b Quelle: F. Jondral, Uni Karlsruhe, Inst. Für Nachrichtentechnik

41 DSSS-Modulation / / / 0 / / 0 / / / Quelle: F. Jondral, Uni Karlsruhe, Inst. Für Nachrichtentechnik

42 HSDPA (Highspeed downlink packet access) enhancements to the WCDMA-based UMTS-technology WCDMA-Networks are using e.g. Fast-Power-Control in order to guarantee quality of service of a connection HSDPA uses the realtime adaptation of modulations (QPSK, 16QAM) and codings dependent upon Channel Quality Indicator data of the UE new transport channel type supports up to 15 multicodes per channel: exclusively to one user or shared between at most 4 users length of transmission window reduced to 2ms packet delivery planning is done by NodeB instead of RNC Downlink up to 2-3Mbit/s (theoretically Mbit/s), Uplink 128Kbit/s low investment (mostly software) provides high capacity improvement HSDPA backwards compatible to WCDMA-UMTS

43 Worldwide Interoperability for Microwave Access (WiMAX) WiMAX Forum 2003 established by 10 companies, today mor than 150 members Intel drives the development (WiMAX air interface will be integrated into next Centrino technology) Marketing, certification, development of system profiles for IEEE , currently IEEE (once d) e for mobile access Adaptive modulation and coding Adaptation of the coding to the signal to noise ratio Quelle: Intel

44 OFDMA (Orthogonal Frequency Division Multiple Access) segmentation of a fast bit stream into several slow bit streams which will be transmitted over different frequencies simultaneously Long symbol duration is more robust against multipath reception minus on bandwidth is compensated by overlapping of the frequency bands, i.e. parallel transmission broad channel segmented into narrow subcarrier Symbols on the subcarriers are orthogonal to each other single subcarriers can be assigned to different users and are not fixed in the spectrum (frequency hopping)

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