F. WANG ET AL.

646

inter-element spacing equals to 0.5 λ. Transmit antenna

selection and beam selections are performed at transmit-

ter side. We can see from these figures that with extra

antennas the hybrid scheme is capable of improving the

SER performance further. One can see from Figure 8, the

system employing ULA shows a much better perform-

ance when AoA = π/6. However, when AoA increased to

π/3, the system employing UCA takes dominant position

(as shown in Figure 9). By comparing Figure 8 and Fig-

ure 9, it is easy to be noted that the increased AoA leads

to a significant decrease in the SER performance for

ULA. This observation confirms the results shown in

Figures 3 and 4 that a UCA receiver is robust to AoA.

The change of AoA results in little change of SER per-

formance for UCA receievr. On the contrary, the receiver

equipped with ULA is sensitive to AoA. An increased

AoA could result in a significant decrease in the SER

performance.

5. Conclusions

In this paper, we have proposed a hybrid transmission

scheme which involves beam selection and antenna se-

lection techniques over a MIMO system operating with

vary antenna array. Optimal subset of transmit antennas

are selected via fast successive selection scheme de-

signed to optimize the target eigenbeam. Optimal eigen-

beams corresponding to the largest singular values of the

new MIMO channel formed by the selected antennas are

exploited for data transmission. We also evaluated the

performance of the proposed scheme with different array

structures. In our simulations, the transmitter is assumed

to be surrounded by scattering objects while the receiver

is postulated to be free from scattering objects. The

Laplacian distribution of angle of arrival (AoA) of a sig-

nal reaching the receiver is postulated. The results show

that the proposed scheme is capable of achieving an im-

proved SER performance. In regards to the array struc-

ture, we can conclude that ULA is preferred when AoA

is small the constant while UCA is favoured when AoA

is varying significantly.

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