It is obvious that when we spread our signal on space, time, and frequency, we had better performance as we were able to maintain maximum achievable spatial diversity on the receiver side.
We showed that our proposed system gives the advantage of maintaining maximum achievable spatial diversity on the receiver side in the case of slow frequency-selective Rayleigh-fading channels.
On the other hand, when we decrease the number of receive antennas to one, our proposed scheme is superior because we are able to maintain maximum possible spatial diversity on the receiver side, but the other scheme is not able to compensate when reducing the number of receive antennas to one.
Tools developed by ALSTOM-TIS allow to realize field measurements and to take into account a simple spatial diversity by keeping the maximum level of the two receivers.
To determine the maximum rate that can be realized when a full spatial diversity is achieved, we need to define the optimal rate-diversity tradeoff [13] which can be characterized by the following equation: (6).
With N transmitter (TX) and M receiver (RX) antennas, the maximum diversity gain is N × M, and the maximum spatial multiplexing gain is min {N, M}.
Following the notion from [34], the spatial diversity gain can be illustrated by assuming a maximum ratio combining (MRC) receiver that combines the signals from independent receive antennas.
To illustrate the attainable frequency and spatial diversity, we consider 10 scenarios shown in Table 2 where the maximum diversity order is computed from (24), (30), and (37).
More spatial diversity gain can be obtained compared with BD precoding when MRT precoding and maximum ratio combining are employed.
Transmit maximum ratio combining (MRC) allows to extend the range of wireless local area networks (WLANs) by exploiting spatial diversity and array gains.
