Showing papers on "Multi-user MIMO published in 1997"

Blind identification and equalization for wireless communications using antenna arrays

Abstract: Antenna arrays can be used in wireless communication systems to increase system capacity and improve communication quality. The antenna arrays, which receive several signals at the same time and frequency domain, can be modeled as a multiple-input/multiple- output (MIMO) system. To separate and recover multiple signals from arrays, the parameters of the system have to be identified explicitly or implicitly. In the first part of this paper, we deal with blind parameter identification based on second-order statistics. We investigate the identifiability of the MIMO FIR channels, and obtain a necessary and sufficient condition for second-order based identifiability of the MIMO FIR channels. Then, we extend the identification algorithms for single-input/multiple- output (FIR-SIMO) channels, such as the algebraic algorithm and the subspace algorithms to the identification of the MIMO FIR channels. The MIMO systems can also be directly equalized using blind techniques. We then investigate blind algorithms to separate multiple signals received by antenna arrays. We analyze the CMA equalizer used in the MIMO systems. According to our analysis, for the MIMO FIR channels satisfying certain conditions, the MIMO-CMA FIR equalizer is able to recover one of input signals and remove the intersymbol interference and co-channel interference regardless of the initial setting of the equalizer. To recover all input signals simultaneously, a novel MIMO channel blind equalization algorithm is developed in this paper. The global convergence of the new algorithm for MIMO channels is proved. Hence, the new blind equalization algorithm for MIMO channels can be applied to separate and equalize the signals received by antenna arrays in communication systems.

Wireless informing system

Abstract: PROBLEM TO BE SOLVED: To speedily execute the installation work of a wireless transmitter by intermittently transmitting a wireless signal for prescribed time through the operation of a test mode switch provided for the wireless transmitter and automatically stopping intermittent transmission after prescribed time passes SOLUTION: An installation-type wireless transmitter 10 detecting the object of a human body and transmitting the wireless signal and a wireless receiver 20 receiving the wireless signal from the transmitter 10 and giving information are provided The unlatch-type test mode switch 10g is provided on the wireless transmitter 10, the wireless signal is intermittently transmitted for prescribed time through the operation of the test mode switch 10 g and intermittent transmission is automatically stopped after prescribed time passes Thus, work accompanied with test transmission becomes easy at the time of providing the wireless transmitter 10 in a position where the wireless receiver 20 can receive the wireless signal COPYRIGHT: (C)1998,JPO

Adaptive identification of discrete-time MIMO systems with possibly different input and output steps

Abstract: An equivalent transformation of ΜΙΜΟ time-invariant systems with different input and output steps to ΜΙΜΟ time-invariant systems with equal input and output steps is described. A new canonical form of ΜΙΜΟ time-invariant systems is defined. The parameter updating algorithm for this canonical form is based on a recursive least square scheme. The convergence of the algorithm is proved. The numerical investigation is carried out. It proves poor convergence of the straightforward least square scheme. Two modifications of the algorithm are developed. They rise the convergence significantly.