We analyze a MIMO DS-CDMA channel with a general multiuser detector including a nonlinear multiuser detector, using the replica method. In the many-user, limit the MIMO DS-CDMA channel with the multiuser detector is decoupled into a bank of single-user SIMO Gaussian channels if a spatial spreading scheme is employed. On the other hand, it is decoupled into a bank of single-user MIMO Gaussian channels if a spatial spreading scheme is not employed. The spectral efficiency of the MIMO DS-CDMA channel with the spatial spreading scheme is comparable with that of the MIMO DS-CDMA channel using an optimal space-time block code without the spatial spreading scheme. In the case of the QPSK data modulation scheme the spectral efficiency of the MIMO DS-CDMA channel with the MMSE detector shows waterfall behavior and is very close to the corresponding sum capacity when the system load is just below the transition point of the waterfall behavior. Our result implies that the performance of a multiuser detector taking the data modulation scheme into consideration can be far superior to that of linear multiuser detectors. Index TermsMultiple-input multiple-output (MIMO) systems, direct-sequence code-division multiple access (DS-CDMA), asymptotic analysis, multiuser detection, replica method.K. Takeuchi is with the

Abstract. [Purpose] In this study, we investigated the effect of exercise using a horse-riding simulator on the physical ability of frail seniors.[Subjects] The subjects consisted of 21 frail seniors living in the vicinity of a day care facility, which they used more than twice each week.[Methods] The subjects were randomly divided into two groups, an exercise group and a control group. The exercise group, in addition to their normal exercise routine at the day care facility, participated in exercise using a horse-riding simulator. The control group continued their normal exercise regime at the facility with no additional exercise. The duration of our research was 12 weeks.[Results] The levels of physical ability of the exercise group were significantly increased after the implementation period relative to the pre-study levels. On the other hand, there was no significant difference in the pre-and post-study levels of the physical ability of the control group. In addition, even in the exercise group, no significant difference in the levels of more complicated movement abilities relative to those of pre-study abilities was observed. [Conclusion] Although the level of physical ability of some frail seniors was increased by exercise using the horse-riding simulator, the exercise did not realize a sufficient increase in the levels of all movement abilities.

No abstract

No abstract

No abstract