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.

There are ever increasing demands for additional capacity in wireless communications to handle voice, data, and wideband Internet applications. These demands are constrained by the bandwidth that was allocated to wireless communications. The spectral efficiencies in present day wireless systems hover around 1 bit/s/Hz. Bell-labs Layered Space-Time (BLAST) is a communication technique for achieving very high spectral efficiencies in highly scattering environments using multiple transmit and receive antennas. A measurement campaign was undertaken to assess the BLAST gains in spectral efficiency in the suburban outdoor environment for stationary subscribers. The measurements employed directive antennas to better control interference from adjacent cells. The measurements were performed over a narrow band at 2.44 GHz with five transmitting and seven receiving antennas, respectively. Extensive calibration methods, assisted by simulations, were developed to assure accurate results for the BLAST capacities of the measured remote subscriber sites. Initial results indicate that BLAST capacities of C/sub B//spl ges/38 bits/s/Hz at 20% of the measured locations and C/sub B//spl ges/24 bits/s/Hz at 50% of these locations are feasible, for reasonable link parameters and negligible interference.

Recent breakthroughs in the application of information theory have shown great capacity increase by deploying multiple transmitting and multiple receiving antennas as compared to conventional single antenna systems. This work presents an experimental verification of the theoretical capacity prediction and a summary of measurement results for 16 fixed wireless locations in suburban New Jersey.