Digital Signal Processing Reference
In-Depth Information
Single-shot synchronization.
Use alternating slots and
rely on delay spread channel.
transmit symbol interval
...
slot 1
slot 2
slot 3
slot 4
slot 5
slot 6
slot 1
slot 2
During data reception: slow tracking of channel characteristics.
Deactivate receive slot
with lowest signal quality.
...
slot 1
slot 2
slot 3
slot 4
slot 5
slot 6
slot 1
slot 2
Relocate inactivated receive
module to a new unused slot.
...
slot 1
slot 2
slot 3
slot 4
slot 5
slot 6
slot 1
slot 2
Figure 5.11.
During synchronization, all available receive modules are evenly dis-
tributed over the interval between two consecutive pulses. During data
reception, the receiver tries to improve its performance by relocating
the slot with the lowest signal output to the oldest unused time slot.
it can be guaranteed that during synchronization sufficient signal power shall
be captured by the remaining receive units, still allowing the receiver to lock
on an incoming transmission burst.
As soon as synchronization has been achieved, the system can start to enhance
its performance using the following algorithm (illustrated in Figure 5.11). First,
the receive branch with the poorest signal quality is selected. Based on an in-
ternal history table which contains the average signal quality for each window
position, the window of the selected branch is relocated to a new position which
is not in use at that moment. During this relocation process, the wireless link
remains fully operational thanks to the
n
1 receive units that are still on-
line. After the disconnected receiver is brought up and is running again, it is
hot-plugged into the system after which the whole procedure starts over. This
way, the receiver can adapt to slow variations in the average characteristics of
the channel without having to chase after every individual multipath compo-
nent. It is emphasized again that the above procedure is entirely client-based,
without any intervention from transmission side. As a result of this feature, the
−
