Showing papers on "Transmit diversity published in 1995"
Patent•
03 Mar 1995
TL;DR: In this paper, a common diversity transmitter is employed for all channels, whereas individual transmitters are employed for the normally transmitted signals in the respective voice channels, and when it is detected that a voice channel needs diversity transmission, a diversity (delayed) signal is automatically transmitted for that channel over an independent path.
Abstract: A cellular system has base stations in which diversity transmission is controllably employed to improve voice communications as needed. Normal signal transmission is employed in each voice channel unless it is detected that quality has dropped to a point where diversity transmission is needed to enhance the quality. When it is detected that a voice channel needs diversity transmission, a diversity (delayed) signal is automatically transmitted for that channel over an independent path. A common diversity transmitter is employed for all channels, whereas individual transmitters are employed for the normally transmitted signals in the respective voice channels.
76 citations
18 Jun 1995
TL;DR: Transmitter weights are derived to maximize the signal to interference noise ratio (SINR) at the output of the matched filter based receiver for each user.
Abstract: Increased demand for wireless communications in the workplace and for cellular communications has revitalized the concept of spaced antenna diversity. Both transmit and receive diversity are being explored to increase the capacity and improve the performance of wireless communication systems. Transmit diversity is the focus of the present paper. Multiple antennas transmit amplitude and phase weighted signals to a single antenna for each user. Fading coefficients were assumed to vary at a slow enough rate so that reliable estimates can be obtained at the transmitter. Transmitter weights are derived to maximize the signal to interference noise ratio (SINR) at the output of the matched filter based receiver for each user.
12 citations
27 Sep 1995
TL;DR: Simulation results show that optimum diversity combining is only useful for a TDD system with a short dwell time, and in the uplink direction M-1 interferers can be suppressed by an M element array.
Abstract: Optimum diversity combining in a wireless communications system using TDMA/TDD is considered. By the use of optimum diversity combining a receiving antenna array is able to suppress interference and thus the capacity of the system is increased. The results in this paper are obtained by simulations. In the simulations a DECT-like system is used as the TDMA/TDD system. The results show that in the uplink direction M-1 interferers can be suppressed by an M element array. However the downlink transmit diversity performance is much worse, due to the changes in the radio channel during the dwell time between the uplink and downlink burst. That is the reason why it is concluded that optimum diversity combining is only useful for a TDD system with a short dwell time.
8 citations