1. In radio signal propagation, there are two kinds of signal fading. The fading caused by buildings shadow is called Slow fading (shadow fading ) .The fading caused by multi-path is called Fast fading (Rayleigh Fading) .
1. In GSM mobile communication system, there are mainly four kinds of diversity technology: space diversity, time diversity , frequency diversity and polarization diversity.
2. Time dispersion mainly refers to the problem of co-frequency interference arising from the time difference between master signals arriving at the receiver and other multi-path signals in terms of time for transmission in space (transmission distance).
3. In a GSM 900 cellular BTS, its Tx band is 935~960 MHZ, and its Rx band is 890~915 MHZ; its duplex interval is 45 MHZ, and its Carrier Frequency interval is 200 KHZ , each Carrier Frequency containing 8 full-rate physical channels.
4. Demodulation is actually a process to reflect the change to the transferred information about such Carrier Frequency parameters as Amplitude, frequency, phase .
5. Electronic map mainly includes such three subdirectories as clutter 、 heights 、vector, which keep the information ASSET can use.
6. In GSM specification, despite what frequency reuse pattern is applied, Carrier/Interference must satisfy following request. Co-frequency C/I ≧ 9 dB. Adjacent frequency C/I ≧ - 9 dB. 400KHZ deviation C/I ≧ - 41 dB. In engineering design, 3 dB more should be considered.
7. The multiple access modes now adopted in wireless communications include FDMA , TDMA , and CDMA
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