Chapter 11 Wireless Systems and Standards

Transcription

1 Chapter 11 Wireless Systems and Standards Yimin Zhang, Ph.D. Department of Electrical & Computer Engineering Villanova University Yimin Zhang, Villanova University 1

2 Evolution Overview Wireless Cordless Japan US Europe Europe US Japan 1st AMPS NMT450 TACS NMT900 NETZ-C RADIOCOM CT0 3 2nd D-AMPS/IS-54 PDC PCS 1900 CDMA/IS-95 GSM 1900 GSM 900 GSM 1800 DECT Paging PACS PHS 3G IMT-2000 Yimin Zhang, Villanova University 2

3 Terminology AMPS (Advanced Mobile Phone System): North American cellular phone standard, operates in 800 MHz and 900 MHz bands. About 85% of AMPS subscribers are in the U.S. GSM (Groupe Speciale Mobile): Digital cellular standard in Europe. DCS 1800 (Digital Communication Service): an extension of GSM standard, operates at 1800 MHz. DECT (Digital European Cordless Telecommunications): a cordless system supporting voice and data. NMT (Nordic Mobile Telephone): one of the first cellular systems, operates in 450 MHz and 900 MHz bands. Used in Scandinavian countries (Norway, Sweden, Finland). TACS (Total Access Communications System): derivative of AMPS developed in U.K. 91% of TACS subscribers come from Europe. TACS/NTT: : Japanese digital transmission scheme, operates in 800 MHz and 1500 MHz bands; based on TDMA/FDD. Yimin Zhang, Villanova University 3

4 1 st ECE 8708 Wireless Communications : Wireless Systems and Standards Generations of Mobile Systems st Generation (1G): Analog Transmission 2 nd AMPS TACS (ETACS) NMT nd Generation (2G): Digital Transmission GSM CT2, CT3 (Cordless Telephone) DECT CDMA 3 rd Generation (3G): Unification of technologies FPLMTS (Future Public Land Mobile Telecommunication Systems) UMTS (Universal Mobile Telecom System) cdma2000, WCDMA (Wideband CDMA) Yimin Zhang, Villanova University 4

5 First Generation - History AMPS: Advance Mobile Phone System First cellular experimental analog systems - AT&T AMPS system (Chicago, IL); channel spacing is 30 KHz First commercial analog system at Chicago, IL; total 40 MHz spectrum in 800 MHz band Additional 10 MHz (extended spectrum) band Motorola developed AMPS-like system N-AMPS (narrowband AMPS); channel spacing is 10 KHz Yimin Zhang, Villanova University 5

6 ETACS: European Total Access Communication System, or TACS - Developed in Mid-1980s; virtually identical to AMPS - The channel spacing is 25 KHz - The mobile identification number (MIN) accommodates country codes. First Generation - History N-AMPS developed by Motorola (3*capacity, still analog) in 1991 Yimin Zhang, Villanova University 6

7 Yimin Zhang, Villanova University 7

8 Second Generation USDC/ CDMA/GSM IS-54 dual mode digital cellular in 1990, also known as USDC (United States Digital Cellular), D-AMPS (Digital AMPS), and NADC (North American Digital Cellular) TDMA/FDD Support 3 full-duplex users on each AMPS channel IS-136 in 1994 (against competition from PCS1900) Design objectives: Higher Capacity Backward compatibility Yimin Zhang, Villanova University 8

9 Second Generation USDC/CDMA/GSM Qualcomm CDMA proposal in 1989 and IS-95 in 1992 GSM (Global System for Mobile Communication) Design objectives: - Standardized Pan-European mobile system - Equivalent traffic capacity to pre-existing 25kHz European analog cellular bandwidth (200kHz/8) - Wireless counterpart for ISDN Yimin Zhang, Villanova University 9

10 Second Generation Share Yimin Zhang, Villanova University 10

11 Yimin Zhang, Villanova University 11

12 User 1 Slot 1 Slot 4 User 2 Slot 2 Slot 5 User 3 Slot 3 Slot 6 Yimin Zhang, Villanova University 12

13 FACCH: Fast Fast Associated Control Control Channel --important control control of of specialized traffic traffic data data (e.g., (e.g., handoff) --within within data data traffic traffic channel Data: total 260 bits Sync: 28 bits SACCH: 12 bits - Slow Associated Control Channel - provides a signaling channel in parallel with the digital speech - carries various control and supervisory messages between the subscriber unit and the base station - used by the mobile unit to report the results of signal strength measurement of neighboring base station CDVCC: 12 bits Coded Digital Verification Color Code - 8 bit information + 4bit coding - MS must receive, decode, and retransmit the same CDVCC Guard: 6 bits - guard bits to compensate for timing differences Ramp: 6 bits - ramp bits to allow for power ramp up of RF signal Yimin Zhang, Villanova University 13

14 Data: total 260 bits Sync: 28 bits SACCH: 12 bits - Slow Associated Control Channel FACCH: Fast Associated Control Channel - within data traffic channel CDVCC: 12 bits Coded Digital Verification Color Code - 8 bit information + 4bit coding - MS must receive, decode, and retransmit the same CDVCC Reserved: 12 bits Yimin Zhang, Villanova University 14

15 Second Generation USDC Channel coding: uncoded information: 77 class-1 bits and 82 class-2 bits. Yimin Zhang, Villanova University 15

16 Interleaving Use two speech frames x and y. Second Generation USDC Yimin Zhang, Villanova University 16

17 Modulation 48.6 kbps over 30 khz band 1.62 bps/hz spectral efficiency π/4-dqpsk is used. Roll-off factor: 0.35 Second Generation USDC Equalization symbol rate : 24.3 ksps maximum rms delay is 4.12µs without equalization Probability that rms delay exceeds 4µs is 25% of the location in 4 cities DFE equalizer: 4 feedforward taps (1/2 symbol spacing), 1 feedback tap Yimin Zhang, Villanova University 17

18 Second Generation USDC IS-136 Final USDC standard provide new features and services to be competitive with IS-95 and GSM. - short message capability - private, user group - sleep mode - control channel changes from 10 kbps FSK to 48.6 kbps DQPSK - IS-54 and IS-136 terminals are not compatible Yimin Zhang, Villanova University 18

19 Second Generation GSM - Before GSM, European countries used different cellular standards throughout Europe. - GSM is now the world s most popular standard for 2nd generation wireless communications in the world. - First introduced in Several non-european countries in South America, Asia, Australia adopted GSM. - GSM uses removable Subscriber Identity Module (SIM) to store information of the subscriber s identification information, network and countries where the subscriber is entitled to service, private keys. Yimin Zhang, Villanova University 19

20 Second Generation GSM Yimin Zhang, Villanova University 20

21 Second Generation GSM GSM System mobile Mobile Station Mobile Equipment Subscriber Identity M odul (SIM) Fixed Radio Network <Base Station Subsystem> (BSS) Base Transceiver Station (BTS) Base Station Controller (BSC) Mobile Switching Network <Switching and Management Subsystem> (SMSS) Mobile Switching Center (MSC) Gateway M obile Switching Center (GM SC) International Switching Center (ISC) Home Location Register (HLR) Visitor Location Register (VLR) Management Network <Operation and Maintenance Subsystem>(OMSS) Operation and Maintenance Center (OMC) Equipment Identity Register (EIR) Authentication Center (AUC) Yimin Zhang, Villanova University 21

22 Second Generation GSM BTS: Provide the radio channel for signaling and user data traffic in this cell BSC: Control of BTSs; Frequency administration MSC : The major tasks of an MSC are routing incoming and outgoing calls and the assignment of user channels on the A-interface. HLR : An HLR can be regarded as a large database that administers the data of literally hundreds of thousands of subscribers. VLR : A VLR contains subscriber data, but only part of the data in the HLR and only while the particular subscriber roams in the area for which thevlr is responsible. ISC: Connections to other mobile or international networks are mostly routed over the International Switching Center (ISC) of the respective country. OMC:Administration and commercial operation; Security management; Network configuration, performance management AUC:Confidential data and keys are stored or generated in AUC EIR:Stores the serial numbers of the terminals Yimin Zhang, Villanova University 22

23 Second Generation GSM - GSM originally used two 25 MHz cellular bands. - GSM uses FDD and a combination of TDMA and FHMA schemes to provide multiple access to mobile users. - Forward and reverse frequency bands are divided into 200 khz wide channels, called ARFCN (Absolute Radio Frequency Channel Numbers). - Each channel is time shared between as many as 8 subscribers using TDMA. - Guard band of 100 khz at each end; total 125 channels (about 1000 users). - ARFCN+TS constitutes physical channel. - Data rate: kbps per channel, kbps per user - Modulation: GMSK modulation with BT=0.3 Yimin Zhang, Villanova University 23

24 Second Generation GSM Yimin Zhang, Villanova University 24

25 Second Generation GSM Yimin Zhang, Villanova University 25

26 Second Generation GSM Yimin Zhang, Villanova University 26

27 Second Generation GSM Yimin Zhang, Villanova University 27

28 Second Generation GSM Signaling Broadcast Channel (BCH) <Downlink> Broadcast Control Channel (BCCH) Synchronization Channel (SCH) Frequency Correction Channel (FCH) Common Control Channel (CCCH) <Down- or Uplink> Random Access Channel (RACH) <Uplink> Access Grant Channel (AGCH) <Downlink> Paging Channel (PCH) <Downlink> Standalone Dedicated Control Channel (SDCCH) Dedicated Control Channel (DCCH) <Bidirectional> Associated Control Channel (ACCH) Slow Associated Control Channel (SACCH) Fast Associated Control Channel (FACCH) Traffic Traffic Channel (TCH) <Bidirectional> Full-rate Channel (Bm) Half-rate Channel (Lm) Yimin Zhang, Villanova University 28

29 Second Generation GSM Yimin Zhang, Villanova University 29

30 Second Generation GSM Yimin Zhang, Villanova University 30

31 Second Generation GSM Yimin Zhang, Villanova University 31

32 Second Generation CDMA - Qualcomm developed CDMA/AMPS dual mode phone in As of 2001, there are over 80 million CDMA subscribers worldwide. - Each IS-95 channel occupies 1.25 MHz on each one way link. Yimin Zhang, Villanova University 32

33 CDMA 24x16 array Yimin Zhang, Villanova University 33

34 CDMA Yimin Zhang, Villanova University 34

35 Yimin Zhang, Villanova University 35

36 Migration Path 2G, 2.5G, 3G Japan PDC W-CDMA Europe GSM GPRS EDGE HSCSD America AMPS/D-AMPS D-AMPS+ IS-95A IS-95B CDMA2000 2G System 3G System Easy upgrade Upgrade requiring new modulation Upgrade requiring entire new radio system Yimin Zhang, Villanova University 36

37 Evolution 2G Handsets This is the current digital mobile phone technology most of us are using. Features includes: Phone calls Voice mail Receive and send SMS Speed: 9.6 kilobits/sec Time to download a 4 min MP3 song: 50 min Yimin Zhang, Villanova University 37

38 Evolution Cont. 2.5G Handsets The best technology now widely available Features includes: Phone calls/fax - always on Voice mail Send/receive large messages Internet browsing GPS Instant news update Speed: >10-144kilobits/sec Time to download a 4 min MP3 song: 7-12min Yimin Zhang, Villanova University 38

39 Evolution Cont. 3G Handsets Combines a mobile phone, laptop PC and television. Features includes: Phone calls/fax - always on Global roaming Send/receive large High speed internet GPS Videoconferencing Live streaming Speed: >144-2 megabits/sec Time to download a 4 min MP3 song: 15sec - 1.6min Yimin Zhang, Villanova University 39

40 1 st ECE 8708 Wireless Communications : Wireless Systems and Standards Generations of Mobile Systems st Generation (1G): Analog Transmission 2 nd AMPS TACS (ETACS) NMT nd Generation (2G): Digital Transmission GSM CT2, CT3 (Cordless Telephone) DECT CDMA 3 rd Generation (3G): Unification of technologies FPLMTS (Future Public Land Mobile Telecommunication Systems) UMTS (Universal Mobile Telecom System) cdma2000, WCDMA (Wideband CDMA) Yimin Zhang, Villanova University 40

41 Homework Assignment (find by yourself for DECT) (optional + 20) Deadline 4/20/05 Before next class begins Yimin Zhang, Villanova University 41