In fact, if we further assume
that each of the receive antennas has the same noise power then we can further simplify the metric.
We will utilize the VA to perform the MLE where each of the D antennas will be utilized sequentially
as follows.
(6.87)
This can be easily extended to the case when the desired signal has delay spread components.
(6.88)
In Fig. 6.17 we provide an overall block diagram of a system where the desired signal encounters
a two-ray channel. The channel has a single interferer experiencing flat fading. The channel estimates
are obtained as previously discussed where q data symbols are consumed before an output
symbol is generated. The MLSE generates various hypothesis signals, sh(k), to use in calculating
the metrics.
A simple block diagram is provided in Fig. 6.18, although it is shown for the flat fading scenario,
it can easily be extended to the frequency selective fading scenario. Each antenna has an independent
channel estimate and the MLSE hypothesis is applied to each antenna.
One can also show that minimizing the above metric, M(k), is equivalent to maximizing the following
relationship [18??“20].
(6.89)
This can be represented with the following block diagram which after careful inspection is equivalent
to MRC combining (see Fig.
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