Mitigation Techniques

1. • Fading mitigations techniques
Diversity-Equlization-Channel Coding
Equalization, diversity, and channel coding are three techniques which can
be used independently or in tandem to improve received signal quality.

2. Equalization compensates for intersymbol
interference (ISI) created by multipath within
time dispersive channels. if the modulation
bandwidth exceeds the coherence bandwidth of
the radio channel, ISI occurs and modulation
pulses are spread in time.

3. Diversity is another technique used to
compensate for fading channel
impairments, and is usually implemented by
using two or more receiving antennas.

4. • while equalization is used to counter the
effects of time dispersion (ISI), diversity
usually employed to reduce the depth and
duration of the fades experienced by a
receiver in a flat fading (narrowband) channel.

5. Diversity techniques can be employed at both base station and mobile
receivers.
The most common diversity technique is called spatial diversity, whereby
multiple antennas are strategically spaced and connected to a common
receiving system. While one antenna sees a signal null, one of the other
antennas may see a signal peak, and the receiver is able to select the
antenna with the best signal at any time.
Other diversity techniques include antenna polarization diversity, frequency
diversity, and time diversity.

6. Channel coding improves mobile communication link performance by ading
redundant data bits in the transmitted message. At the baseband portion of
the transmitter, a channel coder maps a digital message sequence into
another specific code sequence containing a greater number of bits than
originally contained in the message. The coded message is then modulated
for transmission in the wireless channel.

7. The three techniques of equalization, diversity,
and channel coding are used to improve radio
link performance (i.e. to minimize the
instantaneous bit error rate), but the approach,
cost, complexity, and effectiveness of each
technique varies widely in practical wireless
communication systems.