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In this paper, we present a novel method for data detection of M-ary phase shift keying (MPSK) in the presence of unknown carrier phase and additive white Gaussian noise. Here, the unknown carrier phase is rapidly changing and random. That is, the unknown phase changes from symbol to symbol in a nondeterministic manner. The rate of phase change is such that phase change over two symbol intervals is negligible, but it is not necessarily negligible over a longer interval. Our proposed system outperforms traditional differential phase shift keying (DPSK) by 1.5 dB at error probabilities of [10.sup.-3] and [10.sup.-4]. We also compare the performance of our scheme with that of multiple symbol differential detection (MSDD). Except under very slow phase change conditions, our scheme outperforms MSDD.

In this paper, we investigate the effects of antenna directivity and antenna orientation on fading correlation and, therefore, the channel capacity in multiple-input-multiple-output communication systems by means of a spherical simulation model. The correlation is caused by the mutual interaction of the scattering environment and antenna elements. To study the effect of antenna directivity and orientations on the correlation and channel capacity in a more realistic environment, we extend the "one-ring" model to a spherical scattering environment, which is appropriate for narrowband 3-D Rayleigh fading. In our model, scatterers around a subscriber unit are distributed over a sphere centered on the antenna array in the subscriber unit. Antenna directivity is included in a precise way, and the antenna array can be placed in any orientation. Any type of antenna can be studied in the model. Through simulation, we find that directive antenna elements in linear broadside arrays make the channel capacity more strongly directive than when antenna elements are isotropic. Moreover, different antenna patterns and orientations have different outage capacities depending on the interaction of antenna directivities and the incident waves, which shows that the antenna pattern and orientation affect the channel capacity to some extent. In the uniformly scatter-rich environment, the microstrip antenna array can have 10% higher outage capacity than that of the dipole antenna array. [ABSTRACT FROM AUTHOR]