102L3access - Chapter 3 Wireless Systems: Wireless Systems:...

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October, 1997 RF Engineering 102 - V1.00 (c) 1997 Scott Baxter 1 Wireless Systems: Multiple Access Technologies & Standards Wireless Systems: Multiple Access Technologies & Standards Chapter 3
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October, 1997 RF Engineering 102 - V1.00 (c) 1997 Scott Baxter 2 Multiple Access Methods Frequency Time Power TDMA Power FDMA Power CDMA CODE FDMA: AMPS & NAMPS •Each user occupies a private Frequency, protected from interference through physical separation from other users on the same frequency TDMA: IS-136, GSM Each user occupies a specific frequency but only during an assigned time slot. The frequency is used by other users during other time slots. CDMA Each user occupies a signal on a particular frequency simultaneously with many other users, but is uniquely distinguishable by correlation with a special code used only by this user
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October, 1997 RF Engineering 102 - V1.00 (c) 1997 Scott Baxter 3 Survey of Analog Wireless Technologies AMPS IS553 TACS NMT450 NMT900 C-450 Frequency Band Channel Spacing Speech Modulation Freq. Deviation Signalling Modulation Signalling Bit Rate Overlay Signalling? In-Call Supervision In-Call Control 800 900 450 900 450 30 kHz. 25 25 12.5 20 FM 12 kHz. 9.5 5.0 5.0 4.0 Dir.FSK Dir.FSK Aud.FFSK Aud.FFSK Dir.FSK 10 kb/s 8 kb/s 1200 b/s 1200 b/s 5280 b/s no no no no yes SAT SAT ? ? overlay FM FM FM FM NAMPS IS-91 800 10 kHz. FM 5 kHz. Dir.FSK 10 kb/s no DSAT ST ST ? ? overlay DSAT Call Control ST ST ? ? overlay DSAT Paging/Access CCH (f) CCH (f) CCH (f) CCH (f) CCH (f) CCH (f) Handoff Logic BTSLCR BTSLCR BTSLCR BTSLCR BTSLCR BTSLCR
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October, 1997 RF Engineering 102 - V1.00 (c) 1997 Scott Baxter 4 AMPS AMPS: Advanced Mobile Phone System n Developed primarily by Bell Labs to replace low-capacity IMTS n 800 MHz. frequency band is used in North American markets also used in Central/South America, Australia, some Asia dominant standard in the world by size of customer base n Analog FM for speech transmission uses wider deviation than similar land-mobile systems – increases interference margin against co-channel signals compander improves s/n n Signalling at 10 kb/s on dedicated control channels and voice ch. direct FSK modulation error correction with repetition and majority voting; block codes n Call Supervision and status Signalling SAT Tones Signalling Tone
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October, 1997 RF Engineering 102 - V1.00 (c) 1997 Scott Baxter 5 TACS, JTACS, ETACS TACS: Total Access Communications System n Adapted from US AMPS standard for use in the UK in 1985 n 900 MHz. frequency band for Europe, 25 kHz. channel spacing slight reduction in frequency deviation and signalling speed retains AMPS signalling architecture, but with enhancements originally specified for entire band, 1000 channels, but only 600 are part of original TACS allocation, with remainder called Extended TACS (ETACS) currently used in UK, Eire, Spain, Italy, Austria, Malta, Kuwait, UAE, Bahrain, Hong Kong, Singapore, Malaysia, China A variant, JTACS, is used in Japan; also an analog NTT system, not yet included in this chapter n Speech transmission by FM n Signalling at 10 kb/s on FSK n Call Supervision and Control: SAT, Signalling Tone
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October, 1997 RF Engineering 102 - V1.00
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102L3access - Chapter 3 Wireless Systems: Wireless Systems:...

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