In determining RF coverage in CDMA systems, the effect of interference generated from the serving cell as well as the neighboring cells must be considered, this is in contrast to the RF coverage analysis for AMPS cells where interference mainly affects the frequency assignment but not the coverage. The interference margin is dependent upon the … Read more
Time diversity is a technique common to most digital transmission systems. The Rake Receiver is used to find and demodulate multipath signals that are time delayed from the main signal. Rake Receiver to Find and Demodulate Multipath Signals. Data is Interleaved : Spreads Adjacent Data in time to Improve Error Correction Efficiency Convolutional Encoding : … Read more
Make use of a number of receive antennas that are well separated (coherence distance) to generate independent receptions of the transmitted signal. Selection diversity: choose received signal with largest received power, S/N, etc. Switched diversity: choose alternate antenna if signal falls below a certain threshold. Linear combining: linearly combine a weighted replica of all received … Read more
We know that we normally have several independent paths from TX to Rx of different lengths, these are affected and delayed differently, Signals that start out together at the transmitter will be separated in time when they reach the receiver Diversity doesn’t work with Line of Sight, This is exploiting Multipath rather than fighting it … Read more
In GSM system, the interference strength and distribution on each frequency carrier in cell are different, the carrier variation of the bursts of the same communication low the interference on signal, the radio wave interference on communication is equalized. If no hopping is used, the mobile station will always work on fixed frequency carrier, each … Read more
Spurious interference Spurious interference refers to the additive interference generated by the interference source in the working frequency band of the interfered receiver. Spurious interference includes the out of band power leakage of the interference source, amplified background noise, and transmit inter-modulation product. Spurious interference can reduce the signal noise ratio (SNR) of the interfered … Read more