Ergodic Capacity Analysis and Adaptive Transsmion Scheme in Multi-user Distributed Antenna Systems

This paper focuses on analyzing the ergodic capacity performance of limited feedback (LFB) beamforming in multi-user distributed antenna system (DAS). In such a system, multi-user interference (MUI) is inevitably due to the channel uncertainties caused by quantization error. Considering this, we propose a parameter named effective ergodic capacity rate (EECR), which denotes the capacity offset between finite rate feedback and perfect channel state information (CSI). The simulation results show that the derived approximated EECR is very tight to actual EECR. Based on the approximated EECR, an adaptive minimum bit feedback scheme is proposed, which can effectively reduce the overhead of feedback channel and the complexity of the system. The simulation results verify the effectiveness of the proposed scheme.

Reduction of Carbon-bearing Pellets of Oolitic Hematite in a Shaft Furnace

When carbon-bearing pellets of oolitic hematite are treated in a shaft furnace,some problems are typically encountered:the metallization ratio of the metal pellets is low;the carbon-bearing pellets bond with each other at high temperatures;and the separation of phosphorus from iron is difficult.To solve these problems,experiments were conducted on oolitic hematite reduction in a resistance furnace and semi-industrial test shaft furnace.The results showed that the metallization rate reached 90% or greater under the conditions of a reduction temperature of 1 150℃,an atmosphere of simulated flue gas,and a reduction time between 1.5and 2.0h.The problem of high-temperature bonding among pellets can be solved by increasing the strength of the pellets,coating their surface with a surface transfer agent and maintaining an even temperature inside the shaft furnace.The basicity of the ore blend exerted no obvious effect on the magnetic concentrate and phosphorus content.The phosphorus content in the magnetic concentrate can be further reduced by improving the grinding capacity of the ball mills used in the experiments.On the basis of the experimental results related to oolitic hematite reduction with carbon-bearing pellets in a shaft furnace,the experimental requirements were satisfied with an average 88.27%total Fe content and 0.581% P content in the pellets.