Philadelphia University Faculty of Engineering Communication and Electronics Engineering MOBILE COMMUNICATIONS (650539) Part 1 ١ Dr. Omar R Daoud Text Book and References T. Rappaport, “Wireless Communications: Principles and Practice”, 2nd Edition, Prentice Hall, 2002. W. Stalling, “Wireless Communications and Networks”, Pearson Education, 2002. S. Haykin, “Communications Systems”, 4th Edition, John Wiley and Sons., 2001. A. Yoshihiko, “Introduction to Digital Mobile Communication”, John Wiley and Sons., 1997. L. William, “ Mobile Cellular Telecommunications: Analog and Digital Systems”, Mc Graw Hill, 1995. ٢ Dr. Omar R Daoud Course Contents Introduction (1 week) Cellular Concepts, Coverage Principle and Frequency Reuse (2 weeks) Multichannel and Cochannel Schemes (2 weeks) Interference: Cochannel and Adjacent Channel (2 weeks) Fading Models and Prediction of the Median Path Loss (2 weeks) Modulation Techniques (2 weeks) Mobile Communication Systems (2 weeks) Private and Public Access Mobile Radio and Radio Paging (2 weeks) ٣ Dr. Omar R Daoud Mode of Assessment First Exam (20%) Second Exam (20%) Quizzes\Reports\or Projects (10%) Final Exam (50%) ٤ Dr. Omar R Daoud Introduction Mobile/ Wireless Systems Definitions Why Cellular Mobile Systems? Mobile Systems Revolutions ٥ Dr. Omar R Daoud First Mobile Radio Telephone 1924 ٦ Dr. Omar R Daoud Mobile/ Wireless Systems Definitions BS: Base Station; fixed station located on either the center or the edge of a coverage region. Consists of radio channels, transmitter and receivers antennas. MS: a station which is intended for use while in motion at unspecified location. Forward Channel/ downlink: The transmission process from BS to MS. Reverse Channel/ uplink: The transmission process from MS to BS. Handoff: a process of automatically changing frequencies as the mobile unit moves into a different frequency zone. Thus, the call can be continued in a new frequency without redialing. Full Duplex: Transmission and reception on two different channels. Half Duplex: At any time the user can only transmit or receive information. FDD: Frequency Division Duplexing; the radio transmission channels are provided simultaneously for the subscriber and the BS. ٧ Dr. Omar R Daoud Mobile/ Wireless Systems Definitions TDD: Time Division Duplexing; A single radio channel can be shared in time between the subscriber and the BS. Roaming: a MS operate in a service area different than the from which service has been subscribed. MSC: Mobile Switching Center; connects the BS and MS to the PSTN. SSB: Single-sideband FCC: Federal Communications Commission MTS: Mobile Telephone Service IMTS: Improved Mobile Telephone Service AMPS: Advanced Mobile Phone Service TACS: Total Access Communication System NMT: Nordic Mobile Telephone ٨ Dr. Omar R Daoud Mobile/ Wireless Systems Definitions GSM: Global System for Mobile Communications PDC: Personal Digital Cellular HSCSD: High Speed Circuit Switched Data GPRS: General Packet Radio Service EDGE: Enhanced Data rates for Global Evolution ٩ Dr. Omar R Daoud Why Cellular Mobile Systems? To Improve: * Service Capability * Service Performance * Frequency Spectrum Utilization ١٠ Dr. Omar R Daoud Why Cellular Mobile Systems? Improving the Service Capability In a conventional mobile telephone system: It is usually designed by selecting one or more channels from a specific frequency allocation for use in autonomous geographic zones. Each zone is planned to be as large as possible (the transmitted power must be as high as the federal specifications allows). The user must reinitiate the call when moving into a new zone because the call will be dropped. The number of active users is limited to the number of channels assigned to a particular frequency zone. ١١ Dr. Omar R Daoud Why Cellular Mobile Systems? Improving the Service Performance In the conventional mobile telephone systems (MTS, IMTS-MJ and IMTS-MK) a total of 33 channels were allocated. The large number of subscribers created a high blocking probability during the busy hours. Thus a high-capacity systems were needed ١٢ Dr. Omar R Daoud Why Cellular Mobile Systems? Improving the Frequency Spectrum Utilization In a conventional mobile telephone system the frequency utilization measurement is defined as the maximum number of subscribers that could be served by one channel at the busy hour. In such systems the channel can only serve one customer at a time in a whole area. Thus, a new cellular system must be initiated to overcome these limitations. This systems must be: - SSB: divides the allocated frequency band into maximum numbers of channels - Cellular: reuses the allocated frequency band in different geographical locations - Spread-spectrum or Frequency-hopped: generates many codes over a wide frequency band ١٣ Dr. Omar R Daoud Cellular Mobile Telephony Frequency modulation Antenna diversity 2 7 5 3 2 Cellular concept 1 6 3 Bell Labs (1957 & 1960) 4 1 6 2 7 4 Frequency reuse 5 2 7 3 5 Typically every 7 cells 1 6 3 4 1 Handoff as caller moves 2 7 5 Modified CO switch HLR, paging, handoffs Sectors improve reuse Every 3 cells possible ١٤ Dr. Omar R Daoud Mobile Systems Revolutions 1G (AMPS, TACS and NMT): Features: -Analogue systems -FM modulations -Cellular concepts -Hard Handoff ١٥ Dr. Omar R Daoud First Generation Advanced Mobile Phone Service (AMPS) US trials 1978; deployed in Japan (’79) & US (’83) 800 MHz band — two 20 MHz bands TIA-553 Still widely used in US and many parts of the world Nordic Mobile Telephony (NMT) Sweden, Norway, Demark & Finland Launched 1981; now largely retired 450 MHz; later at 900 MHz (NMT900) Total Access Communications System (TACS) British design; similar to AMPS; deployed 1985 Some TACS-900 systems still in use in Europe ١٦ Dr. Omar R Daoud Mobile Systems Revolutions 2G (GSM, IS-95, PDC): Features : -Digital Mobile phones -Digital modulation -Data compression -Error control -Soft Handoff -SMS -High quality voice -More capacity/ each cell are divided among several users. ١٧ Dr. Omar R Daoud Second Generation — 2G There are a wide diversity of 2G systems IS-54/ IS-136 North American TDMA; PDC (Japan) iDEN DECT and PHS IS-95 CDMA (cdmaOne) GSM ١٨ Dr. Omar R Daoud D-AMPS/ TDMA & PDC Speech coded as digital bit stream Compression plus error protection bits Aggressive compression limits voice quality Time division multiple access (TDMA) 3 calls per radio channel using repeating time slices Deployed 1993 (PDC 1994) Development through 1980s; bakeoff 1987 IS-54 / IS-136 standards in US TIA ATT Wireless & Cingular use IS-136 today Plan to migrate to GSM and then to W-CDMA PDC dominant cellular system in Japan today NTT DoCoMo has largest PDC network ١٩ Dr. Omar R Daoud iDEN Used by Nextel Motorola proprietary system Time division multiple access technology Based on GSM architecture 800 MHz private mobile radio (PMR) spectrum Just below 800 MHz cellular band Special protocol supports fast “Push-to-Talk” Digital replacement for old PMR services Nextel has highest APRU in US market due to “Direct Connect” push-to-talk service ٢٠ Dr. Omar R Daoud DECT and PHS Also based on time division multiple access Digital European Cordless Telephony Focus on business use, i.e. wireless PBX Very small cells; In building propagation issues Wide bandwidth (32 kbps channels) High-quality voice and/or ISDN data Personal Handiphone Service Similar performance (32 kbps channels) Deployed across Japanese cities (high pop. density) 4 channel base station uses one ISDN BRI line Base stations on top of phone booths Legacy in Japan; new deployments in China today ٢١ Dr. Omar R Daoud North American CDMA (cdmaOne) Code Division Multiple Access All users share same frequency band Discussed in detail later as CDMA is basis for 3G Qualcomm demo in 1989 Claimed improved capacity & simplified planning First deployment in Hong Kong late 1994 Major success in Korea (1M subs by 1996) Used by Verizon and Sprint in US Simplest 3G migration story today ٢٢ Dr. Omar R Daoud cdmaOne — IS-95 TIA standard IS-95 (ANSI-95) in 1993 IS-95 deployed in the 800 MHz cellular band J-STD-08 variant deployed in 1900 MHz US “PCS” band Evolution fixes bugs and adds data IS-95A provides data rates up to 14.4 kbps IS-95B provides rates up to 64 kbps (2.5G) Both A and B are compatible with J-STD-08 All variants designed for TIA IS-41 core networks (ANSI 41) ٢٣ Dr. Omar R Daoud GSM « Groupe Special Mobile », later changed to « Global System for Mobile » Joint European effort beginning in 1982 Focus on seamless roaming across Europe Services launched 1991 Time division multiple access (8 users per 200KHz) 900 MHz band; later extended to 1800MHz Added 1900 MHz (US PCS bands) GSM is dominant world standard today Well defined interfaces; many competitors Network effect (Metcalfe’s law) took hold in late 1990s Tri-band GSM phone can roam the world today ٢٤ Dr. Omar R Daoud Mobile Systems Revolutions 2.5G (HSCSD,GPRS, EDGE): Features : 2.5G is an interim solution designed to allow for improved data rates prior to 3G implementation. A variety of 2.5G techniques are being employed to improve the speed of data for enhanced e-mail and Internet access. ٢٥ Dr. Omar R Daoud Mobile Systems Revolutions 3G (UMTS, WCDMA): Features : -Digital multimedia handset. High data transmission rate > 100kbps. Providing much more basic voice call. -Dynamic RRM. -Packet data. ٢٦ Dr. Omar R Daoud 3G Vision Universal global roaming Multimedia (voice, data & video) Increased data rates 384 kbps while moving 2 Mbps when stationary at specific locations Increased capacity (more spectrally efficient) IP architecture ٢٧ Dr. Omar R Daoud CDMA2000 Pros and Cons Evolution from original Qualcomm CDMA Now known as cdmaOne or IS-95 Better migration story from 2G to 3G cdmaOne operators don’t need additional spectrum 1xEVD0 promises higher data rates than UMTS, i.e.