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GSM 900
channels 0 – 124, 955 – 1023
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876.2 to 914.8 MHz (uplink),
921.2 to 959.8 MHz (downlink)
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GSM 1800
channels 512 – 885
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1710.2 to 1784.8 MHz (uplink),
1805.2 to 1879.8 MHz (downlink)
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GSM 1900 (Americas)
channels 512 – 810
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1850.2 to 1909.8 MHz (uplink),
1930.2 to 1989.8 MHz (downlink)
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GSM 850 (Americas)
channels 128 – 251
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824.2 to 848.8 MHz (uplink),
869.2 to 893.8 MHz (downlink)
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Modulation
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GMSK (Gaussian Minimum Shift Keying), phase shifts of π/2 (90°) on symbol transitions
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Access format
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TDMA (time-division multiple access)
TDD/FDD (time and frequency division duplex)
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Number of channels per carrier
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8 time slots per TDMA frame (4.615 ms)
148 bits per time slot, equivalent to 577 µs
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Speech
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Digital transmission with one out of several possible vocoders:
Full rate speech (13 kbit/s)
RPE-LTP (regular pulse excited code with long term prediction)
Enhanced full rate speech (12.2 kbit/s)
ACELP (algebraic code excited linear prediction)
Half rate speech (5.6 kbit/s)
VSELP (vector sum excited linear predictor)
Adaptive multirate (AMR), dynamic operation on full and half rate channel depending on capacity and reception quality
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Power control
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Yes, in 2-dB steps over a range of 30 dB
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