At this point the UE can either work under the assumption
that the correct weight was applied (even though this maybe false) or it can determine the
actual weight applied. In this latter case, there must be a mechanism within the communication
system to support this feature.
A block diagram of the CLTD communication system is shown below. Note Fig. 5.72 assumes a
single receive antenna to be used by the UE, obviously nothing precludes the UE from using more
than 2 antennas.2 Also, we have drawn a second set of antennas for transmit and receive functionality.
In a typical application, an antenna would be used for both transmit and receive.
So for a single receive antenna at the UE, the received signal is given by the following equation:
(5.151)
Note in this transmit diversity example, the same symbol is transmitted on both antennas, the exception
being that the antenna weights (w1 and w2) are different.
Phase Only Adjustments. We will impose the following constraint: . Moreover,
in an effort to effectively present the CLTD concept, we will further constrain w1 to equal 1/!??“
2. This
Zw1 Z2 Zw2 Z2 1
r d # w1 # h1 d # w2 # h2 noise
PERFORMANCE IMPROVEMENT TECHNIQUES 283
Modulator
w2
Demod FEC X
X
Determine
Feedback
Weights Modulator Slot
Format
Weight Estimate
Quantization
w1
Closed Loop
FIGURE 5.
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