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User Throughput Estimation for the PF Scheduling Algorithm under MIMO Channel Environments
Jeongsik Choi,Yong-Hwa Kim,Jong-Ho Lee,Saewoong Bahk,Seong-Cheol Kim IEEE 2012 IEEE wireless communications letters Vol.1 No.5
<P>In cellular systems, user throughput estimation is needed for cell-site selection, handover design, etc. This letter introduces long-term average user throughput estimation methods for the proportional fair (PF) scheduling algorithm under multiple-input multiple-output (MIMO) channel environments. From the observation that the current data rate divided by the long-term average throughput of each user is roughly around a similar level, we propose estimation methods for both single user MIMO (SU-MIMO) and simple multiuser MIMO (MU-MIMO) scheduling scenarios. Since our throughput estimation methods do not depend on the statistics of other users' data rates, they can be easily implemented in practical systems regardless of user data rate distribution.</P>
Throughput Estimation Based Distributed Base Station Selection in Heterogeneous Networks
Jeongsik Choi,Woong-Hee Lee,Yong-Hwa Kim,Jong-Ho Lee,Seong-Cheo Kim IEEE 2015 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.14 No.11
<P>Small cells are considered an emerging technology for increasing the potential capacity of cellular networks. However, as the density of infrastructure increases, users have many choices for connection, and therefore, selecting an appropriate base station (BS) becomes an important issue. This study aims to provide an improved user association rule, where each user autonomously chooses the best among all the BSs in the vicinity, while considering their congestion levels. As the first step, an optimization problem is formulated, which emphasizes both the time-varying nature of the wireless channel and fairness among users. On the basis of this formulation, the influence of a specific handover event on system performance is investigated, and then, two versions of the handover frameworks are developed. Simulation results show that the proposed algorithms increase the throughput of every user in the network by 2.8-12% compared to the best conventional scheme. Furthermore, these schemes especially enhance the performance of users having low service quality by 5.0-85%, through efficient utilization of the pre-installed infrastructures.</P>
IEEE 2018 IEEE antennas and wireless propagation letters Vol.17 No.3
<P>The millimeter-wave (mmWave) band has attracted great attention as promising spectrum for the next-generation cellular systems. However, mmWave communication systems have encountered several challenges because of different electromagnetic characteristics compared with existing spectrum below-6 GHz systems. In order to evaluate the technical feasibility of mmWave provision, 28 GHz mmWave band channel models were presented by developing an efficient three-dimensional (3-D) ray-tracing simulation. The accuracy of 3-D ray-tracing simulation was verified by comparing its results with actual measurements. The path loss (PL) agreed well in both line-of-sight (LOS) and non-line-of-sight (NLOS) regions, whereas the shadowing factor exhibited differences in the NLOS regions. The contributions of this work include confirmation of the applicability of single- and dual-slope LOS and NLOS PL models with different threshold distances for NLOS regions with low root-mean-square errors.</P>
Video streaming exploiting multiple-antenna techniques of wirelessMAN-advanced systems
Jeongsik Yun,Sanghyun Bak,Nulibyul Kim,Kwanghoon Choi,Jaekwon Kim IEEE 2012 IEEE transactions on consumer electronics Vol.58 No.3
<P>In this paper, a novel video streaming technique is proposed for the recently standardized IEEE802.16m system also known as the Wireless MAN-Advanced or WIMAX2 system. The antenna mode considered is single user spatially multiplexed (SUSM) transmission suitable for video streaming. In previous works, the linear signal detection method was used in order to achieve unequal error protection (UEP). In this paper, it is shown that a joint signal detection method can also be used to achieve UEP. Computer simulations demonstrate improved performance using the proposed method. In the simulations, H.264/AVC compressed video is used, and the PHY layer procedures such as resource unit allocation, convolutional turbo code (CTC), pilot tone insertion, and pre-coding are implemented in strict accordance with the IEEE 802.16m standard.</P>