Lecture11
- 1. UNIT-2 Point-to-Point Communication: Detection in a Rayleigh Fading Channel Time Diversity Antenna Diversity . Frequency Diversity Impact of Channel Uncertainty
- 2. Diversity
- 6. • Similarly Transmit Diversity, if there are multiple Transmit antenna. • And it is also possible multiple transmit as well as receive antenna than both Transmit as well as receive diversity. • Similarly we can send the signal at different time slot it is called as Temporal diversity
- 7. • Similarly, signal is send at different carrier a frequency called frequency diversity. • Transmit the signal between different user called multi user diversity. • Hence Diversity play a major role to combat fading and decrease the bit error rate and improves the performance.
- 33. Receive Diversity • In a flat fading channel with 1 transmit antenna and L receive antenna, , the channel model is as follows: • where the noise and independent across the antennas.
- 34. • We would like to detect • If the antennas are spaced sufficiently far apart, then we can assume that the gains are are independent Rayleigh, and we get a diversity gain of L.
- 35. • With receive diversity, there are actually two types of gain as we increase L. • for the error probability of BPSK conditioned on the channel gains:
- 36. • We can break up the total received SNR conditioned on the channel gains into a product of two terms: • The first term corresponds to a power gain (also called array gain): by having multiple receive antennas and coherent combining at the receiver, the effective total received signal power increases linearly with L:The second term reflects the diversity gain:
Editor's Notes
- #2: 2