Wireless Communications

Lecture 16

Diversity

1. Combining Methods and diversity gain

· Selection Combining

· Equal gain combining

· Maximum ratio combining

· Overhead of Combining Methods

Space Diversity

· Antennas separated by lambda/2 or more

· Alamouti and space-time codes

· Somewhat opposite of beam-steering which is more relevant to MIMO

Frequency Diversity

· Multiple carrier frequencies – esp. OFDM

· CDMA/ Spread Spectrum Systems IS-95

· Frequency Hopping Systems

Path Diversity

· RAKE Receiver

Time Diversity

· Interleaving

· Retransmission of signals

· Repetition coding or more elegant additions of redundancy

Polarization Diversity

· Outline my paper