A distributed antenna system (DAS) is very attractive, since it can reduce transmit power by shortening the distance between antenna elements (AEs) and the mobile station. This paper investigates the channel capacity of the DAS over a multi-path frequency-selective fading channel. We first show that the optimal power allocation solution to approaching the channel capacity is unrealistic for the practical DAS. Then, a near-optimal scheme is given through maximally tightening the upper bound of the channel capacity. Approximate analytical results are obtained through the use of the central-limit theorem. Both simulation and theoretical results are presented to show that the channel capacity can be greatly enhanced by the proposed power allocation schemes. Moreover, the bit error rate performance is analyzed for the proposed scheme.

A collaborative design frame based on virtual prototype and virtual manufacturing (CDFVPM) is explored. In CDFVPM, the virtual product prototype (VPP) used as a product shared information database, and to view the product during design process before creation of any physical prototype, to detect the product's performance by simulating the product's working process and interactive using process. The engineers related to developing products do collaborative jobs by working on the virtual product prototypes. The synthetic evaluation system (SES) is used to evaluate the product's quality and performance at every phase during product development process. Virtual manufacturing system (VMS) is used as a visual interactive simulation environment so that the engineers or customers are immersed in this environment and designed products are apperceived or controlled. By supporting of VPP/SES/VMS, the product development cycle will be shortened considerably; the product quality and performance will also be ensured effectively. Application examples are given.