Sung-Soo Hwang

Multi-beam multiplexing using multiuser diversity and random beams in wireless systems

In this paper, we propose a new multiple-access transmission scheme that can simultaneously achieve both diversity and multiplexing gain in the multi-user domain, by using multiple random beams. Multiple beams are generated so that the users encounter multiple channels at the same rime, enabling the use of multi-user diversity through each channel. Since the transmit power is spilt into multiple channels, the signal-to-noise power ratio (SNR) of each channel is reduced in proportion to the number of beams. However, multiple beams are generated so that the multiplexing gain is much larger than the decrease of SNR, increasing the overall system capacity. The proposed scheme works well in both Rician and Rayleigh fading channels regardless of the channel correlation, providing the maximum capacity in multiuser and multi-antenna systems in practice. The proposed scheme is applicable to both MIMO and MISO systems, enabling the use of receivers with flexible antenna structure.

Multiuser diversity and multiplexing using multiple random beams in wireless systems

In this paper, we propose a new multiple-antenna transmission scheme that can simultaneously achieve both diversity and multiplexing gain in the multiuser domain, by using multiple random beams. Multiple beams are generated so that the users encounter multiple channels at the same time, enabling the use of multiuser diversity through each channel. Although the signal-to-noise power ratio (SNR) of each channel is reduced in proportion to the number of beams, multiple beams are generated so that the multiplexing gain is larger than the decrease of SNR, increasing the overall system capacity

An Enhanced V-BLAST System for Reduced-Complexity Tree Searching

This paper presents a new vertical Bell labs layered space-time (V-BLAST) transmission scheme for developing reduced-complexity receiver. It can significantly alleviate the receiver complexity in sense of tree searching of the QRD-M algorithm. The new V-BLAST system is designed by two criteria: minimum performance loss and maximum complexity reduction. In a 4 times 4 V-BLAST system with 16 bps/Hz, the former can lessen about 51% metric computations with 1.0 dB performance degradation, compared with the conventional V-BLAST system with the QRD-M algorithm. The latter can achieve approximately 65% complexity reduction at the expense of 3.0 dB performance penalty.