Abstract-In this paper, a multiple-input-multiple-output (MIMO) extension for a third-generation (3G) wireless system is described. The integration of MIMO concepts within the existing UMTS standard and the associated space-time RAKE receiver are explained. An analysis is followed by a description of an actual experimental MIMO transmitter and receiver architecture, both realized on digital signal processors (DSPs) and FPGAs within a precommercial OneBTS base station. It uses four transmit and four receive antennas to achieve downlink data rates up to 1 Mb/s per user with a spreading factor of 32 and the UMTS chip rate of 3.84 MHz. Furthermore, different MIMO detectors are evaluated, comparing their performance and complexity. System performance is evaluated through simulations and indoor over-the-air measurements. Capacity and bit-error rate measurement results are presented.Index Terms-OneBTS, rapid prototyping, third-generation (3G), UMTS, wireless multiple-input-multiple-output (MIMO) systems.

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A new waveguide array multiplexer design is presented, which is particularly suitable for making broad-band low-order devices. Two channel multiplexers at 1.0-1.55 pm, 131-1.53 pm and 1.47-1.55 pm are demonstrated. Compared to conventional waveguide multiplexers, these devices have wide spectral ranges of low crosstalk. The devices are polarization independent. The crosstalk and fiber-to-fiber insertion loss for the 131-1.53 pm multiplexer were the lowest yet reported for array multiplexers: about -35 and -2 dB, respectively.

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A four-port bandpass filter is demonstrated with good performance by use of UV-induced Bragg gratings in P-doped channel waveguides without UV trimming. The simple, single-step fabrication procedure is experimentally and theoretically analyzed, and tolerances are calculated for achieving practical wavelength-division-multiplexed communication system performance.