Yoshiaki Amano

Forward link throughput evaluation of a SDMA based wireless packet cellular system

In selecting access terminals (AT) for simultaneous transmission, the effectiveness of the spatial-domain scheduler is one of the key factors that affect the performance of the space division multiple access (SDMA) based wireless packet cellular system. The forward link throughput of an SDMA based wireless packet cellular system, to the ability of our proposed quasioptimal weight priority scheduling and beam forming scheme, was evaluated under a condition that is similar to the field environment. The optimal AT directional separation conditions which promise the maximum median cell throughput have been obtained. Simulation results show that more than 10 times the total cell throughput is obtained over that of the system with an omni-antenna. The typical base station equipped with a three-sector antenna can get no more than 3 times the throughput of that with omni-antenna; therefore, the SDMA based wireless packet cellular system discussed has great potential in the future of wireless high-speed data communication.

Downlink beamforming performance of SDM enabled cellular systems

The authors have studied the packet cellular system utilizing SDM (space division multiplexing) technology. This paper evaluates downlink beamforming performance of SDM based FDD packet cellular system by computer simulation under the condition that access terminals are independently and identically distributed in each cell following uniform distribution utilizing premeasured radiation patterns of the 12-element circular array antenna and makes explicit the relation between the angular spread and the number of spatial scheduled users corresponding to the maximal cell throughput. The simulation results show that the average cell throughput can reach up to 9Mbps. The results also show that as angular spread increases, average cell throughput becomes smaller, but can still reach up to 4.44Mbps even when angular spread equals to 10 degree. This indicates that the realistic approaches we adopted are quite promising for next generation mobile communication systems.

Forward Link Beamforming Performances of FDD-SDMA Packet Cellular Testbed System

We carried out field trials of the developed FDD-SDMA packet cellular testbed system and demonstrated the effectiveness of the proposed forward link beamforming algorithm. Our forward link beamforming algorithm use not only unidirectional access terminal estimation but also angular spread estimation that is the proposed method and available to extract angular spread characteristics from a correlation matrix accumulated with reverse link signals through eigen decomposition. Moreover, the proposed beamforming algorithm is equipped with forward link array antenna weighting vector normalization to prevent from demodulation and channel estimation errors with omni-beamformed pilot channel. During the field trials, we confirmed that the throughput performance per access point of the proposed forward link beamforming algorithm exceeded that of the conventional beam-null forming algorithm with only unidirectional access terminal estimation and were convinced of the effectiveness of the proposed algorithm in a real field environment with angular spread