18-07-2012, 01:39 PM
DSP for Wireless
[attachment=27950]
The Matched Filter Principle
The optimum receiver for any signal
in Additive white Gaussian Noise
over a Linear Time-Invariant Channel
is ‘a matched filter’:
Antenna (or micro) diversity.
at the mobile
Covariance of received signal amplitude
J02(2πfDτ) = J02(2πd/λ).
antenna spacing of λ/2 is enough
- at the base station
All signal come from approximately the same direction
received signals are highly correlated
Larger antenna separation needed
Relevant parameter:
distance between scattering objects antenna (typically, a is 10 .. 100 meters), and
distance between mobile and base station.
Site (or macro) diversity
Receiving antennas are located at different sites.
Example: at the different corners of hexagonal cell.
Advantage: multipath fading, shadowing, path loss and interference all become "independent"
Frequency diversity
Each message is transmitted at different carrier frequencies simultaneously
Frequency separation >> coherence bandwidth
Advanced user separation in DS
More advanced signal separation and multi-user detection receivers exist.
Matched filters
Successive subtraction
Decorrelating receiver
Minimum Mean-Square Error (MMSE)
Software radio
Many functions are executed in software anyhow
There are many different radio standards, multi-mode is the way to go.
Can we share functions?
Can we realize a steep cost reduction on DSP platforms?
Architectural choices:
what to make in dedicated hardware?
what to do in programmable ‘filters’?
which operations are done by a general purpose processor?
[attachment=27950]
The Matched Filter Principle
The optimum receiver for any signal
in Additive white Gaussian Noise
over a Linear Time-Invariant Channel
is ‘a matched filter’:
Antenna (or micro) diversity.
at the mobile
Covariance of received signal amplitude
J02(2πfDτ) = J02(2πd/λ).
antenna spacing of λ/2 is enough
- at the base station
All signal come from approximately the same direction
received signals are highly correlated
Larger antenna separation needed
Relevant parameter:
distance between scattering objects antenna (typically, a is 10 .. 100 meters), and
distance between mobile and base station.
Site (or macro) diversity
Receiving antennas are located at different sites.
Example: at the different corners of hexagonal cell.
Advantage: multipath fading, shadowing, path loss and interference all become "independent"
Frequency diversity
Each message is transmitted at different carrier frequencies simultaneously
Frequency separation >> coherence bandwidth
Advanced user separation in DS
More advanced signal separation and multi-user detection receivers exist.
Matched filters
Successive subtraction
Decorrelating receiver
Minimum Mean-Square Error (MMSE)
Software radio
Many functions are executed in software anyhow
There are many different radio standards, multi-mode is the way to go.
Can we share functions?
Can we realize a steep cost reduction on DSP platforms?
Architectural choices:
what to make in dedicated hardware?
what to do in programmable ‘filters’?
which operations are done by a general purpose processor?