VNU-UET Repository: No conditions. Results ordered -Date Deposited. 2024-03-29T14:38:28ZEPrintshttp://eprints.uet.vnu.edu.vn/images/sitelogo.pnghttps://eprints.uet.vnu.edu.vn/eprints/2022-03-21T00:41:51Z2022-03-21T00:41:51Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4694This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46942022-03-21T00:41:51ZMỘT GIAO THỨC TRUY CẬP NGẪU NHIÊN
CHO HỆ THỐNG CELL-FREE MASSIVE MIMOmMTC (truyền thông cho tập hợp lớn máy
móc) là một thành phần quan trọng của mạng sau 5G
(B5G) và của cách mạng công nghiệp 4.0. Do phải đáp
ứng nhiều yêu cầu kết nối cùng một lúc nên xây dựng
một giao thức truy cập ngẫu nhiên hiệu quả là vấn đề
rất quan trọng. Trong bài báo này chúng tôi phát triển
giao thức A-ACB, đã được đề xuất cho hệ thống
Cellular Massive MIMO, sang áp dụng cho hệ thống
Cell-Free Massive MIMO. Kết quả phân tích và mô
phỏng cho thấy giao thức này vẫn đảm bảo mức độ hiệu
quả cần thiết, trong khi giao thức SUCRe, một giao
thức khá hiệu quả trong hệ thống Cellular Massive
MIMO, lại tỏ ra kém hiệu quả trong hệ thống không
phân chia tế bào. Kết luận rút ra ở đây là trong ứng
dụng mMTC, theo hướng nghiên cứu phân giải va chạm
trong truy cập ngẫu nhiên dựa trên cấp phát (Grant�based) thì giao thức A-ACB là một ứng viên tiềm năng
tốt.Xuân Sơn Hà20025067@vnu.edu.vnGia Hưng Hoànghunghg@vnu.edu.vnAnh Vu Trinhvuta@vnu.edu.vn2022-03-21T00:41:38Z2022-03-21T00:41:38Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4695This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/46952022-03-21T00:41:38ZA Random Access Protocol for Massive MIMO:
The Adaptive ACB based Collision ResolutionmMTC (massive Machine Type
Communications) is one of the key components in beyond 5G
networks for smart manufactures and the fourth industrial
revolution. Due to the massive connectivity in mMTC, it is vital
to have an efficient random access protocol. In the paper, we
propose a new random access technique called the Adaptive
ACB (A-ACB) to minimize collisions. We show that, in terms of
successfully resolved probability, the proposed A-ACB always
outperforms the ACBPC protocol [1] and surpasses the SUCRe
protocol [2] when the number of collisions per preamble is large.
In addition, the proposed protocol achieves better fairness than
the SUCRe but less than the ACBPC. Finally, numerical results
are provided to demonstrate the effectiveness of the proposed
random access protocol.Huu Ha Tranhuuha.tran306@gmail.comChu Huy Duongduongch.hyn@gmail.comAnh Vu Trinhvuta@vnu.edu.vnXuan Thang Vuthang.vu85@gmail.comGia Hung Hoanghunghg@vnu.edu.vn2020-12-04T08:27:29Z2020-12-04T08:27:29Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/4125This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/41252020-12-04T08:27:29ZCache-aided Full-Duplex: Delivery Time Analysis
and OptimizationEdge caching has received much attention as a promising technique to overcome the stringent latency and data-hungry challenges in the future generation wireless networks. Meanwhile, full-duplex (FD) transmission can
improve the spectral e�ciency by allowing a node to receive and transmit on the same frequency band simultaneously. In this paper, we investigate the de-
livery time performance of a cache-aided FD system, in which an edge node, operates in FD mode, serves users via wireless channels and is equipped with a cache memory. Firstly, we derive a closed-form expression for the average delivery time by taking into account the uncertainties of both backhaul and access wireless channels. The derived analysis allows the examination of the impact of the key parameters, e.g., cache size and transmit power. Secondly, a power optimization problem is formulated to minimize the average delivery time. To deal with the non-convexity of the formulated problem, we propose an iterative optimization algorithm based on the bisection method. Finally, numerical results are presented to demonstrate the e�ectiveness of the pro-posed algorithm, which can signi�cantly reduce the delivery time compared to the FD reference and the half-duplex counterpart.Xuan Thang Vuthang.vu85@gmail.comAnh Vu Trinhvuta@vnu.edu.vnXuan Nam Trannamtx@mta.edu.vn2019-12-09T03:39:45Z2019-12-09T03:39:45Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3602This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/36022019-12-09T03:39:45ZModeling a Virtual Reality System with Caching and Computing Capabilities at Mobile User’ DeviceVirtual reality (VR) recently is a promising technique in both industry and academia due to its potential applications in immersive experiences including website, game, tourism, or museum. VR technique provides an amazing 3-Dimensional (3D) experiences by requiring a very high amount of elements such as images, texture, depth, focus length, etc. However, in order to apply VR technique to various devices, especially in mobiles, ultra-high transmission rate and extremely low latency are really big challenge. Considering this problem, this paper proposes a novel combination model by transforming the computing capability of VR device into an equivalent caching amount while remaining low latency and fast transmission. In addition, Classic caching models are used to computing and catching capabilities which is easily apply to multi-user modelsCong Huy Phihuypc@ptit.edu.vnHuu Ha Tranhuuha.tran306@gmail.comAnh Vu Trinhvuta@vnu.edu.vnXuan Thang Vuthang.vu@uni.lu2019-12-09T03:35:08Z2019-12-09T03:35:08Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3593This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/35932019-12-09T03:35:08ZFull-Duplex Enabled Mobile Edge Caching: From Distributed to Cooperative CachingMobile edge caching (MEC) has received much attention as a promising technique to overcome the stringent latency and data hungry requirements in the future generation wireless networks. Meanwhile, full-duplex (FD) transmission can
potentially double the spectral efficiency by allowing a node to receive and transmit simultaneously. In this paper, we investigate the delivery time performance of full-duplex enabled MEC (FDMEC) systems, in which the users are served by distributed edge nodes (ENs), which operate in FD mode and are equipped with a limited storage memory. Firstly, we analyse the FD-MEC with different levels of cooperation among the ENs and take into account the realistic model of self-interference cancellation. Secondly, we propose a framework to minimize the system delivery time of FD-MEC under both linear and optimal precoding designs. Thirdly, to deal with the non-convexity of the formulated problems, two iterative optimization algorithms are proposed based on the inner approximation method, whose convergence is analytically guaranteed. Finally, the effectiveness of the proposed designs are demonstrated via extensive numerical results. It is shown that the cooperative scheme mitigates inter-user and self interference significantly better than the distributed scheme at the expense of inter-EN cooperation. In addition, we show that minimum mean square error (MMSE)-based precoding design achieves the best performance-complexity trade-off, compared with the zero-forcing and optimal designs.Xuan Thang Vuthang.vu85@gmail.comSymeon ChatzinotasChatzinotas@gmail.comBj¨orn Otterstenbjorn.ottersten@uni.luAnh Vu Trinhvuta@vnu.edu.vn2019-05-27T08:28:49Z2019-05-27T08:28:49Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3456This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34562019-05-27T08:28:49ZCooperative Caching in Two-Layer Hierarchical Cache aided SystemsCaching has received much attention as a promising technique to overcome high data rate and stringent latency requirements in the future wireless networks. The premise of caching technique is to prefetch most popular contents closer to end users in local cache of edge nodes, e.g., base station (BS). When a user requests a content that is available in the cache, it can be served directly without being sent from the core network. In this paper, we investigate the performance of hierarchical caching systems, in which both BS and end users are equipped with a storage memory. In particular, we propose a novel cooperative caching scheme that jointly optimizes the content placement at the BS’s and users’ caches. The proposed caching scheme is analytically shown to achieve a larger global caching gain than the reference in both uncoded – and coded caching strategies. Finally, numerical results are presented to demonstrate the effectiveness of our proposed caching algorithm.Van Xiem Hoangxiemhoang@vnu.edu.vnthi Hang duonghangdt@haui.edu.vnAnh Vu Trinhvuta@vnu.edu.vnXuan Thang Vuthang.vu85@gmail.com2018-12-14T01:42:08Z2018-12-18T07:02:04Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3249This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32492018-12-14T01:42:08ZCooperative Caching in Two-Layer Hierarchical Cache-aided SystemsCaching has received much attention as a promising technique to overcome high data rate and stringent latency requirements in the future wireless networks. The premise of caching technique is to prefetch most popular contents closer to end users in local cache of edge nodes, e.g., base station (BS). When a user requests a content that is available in the cache, it can be served directly without being sent from the core network. In this paper, we investigate the performance of hierarchical caching systems, in which both BS and end users are equipped with a storage memory. In particular, we propose a novel cooperative caching scheme that jointly optimizes the content placement at the BS’s and users’ caches. The proposed caching scheme is analytically shown to achieve a larger global caching gain than the reference in both uncoded – and coded caching strategies. Finally, numerical results are presented to demonstrate the effectiveness of our proposed caching algorithmVan Xiem Hoangxiemhoang@vnu.edu.vnHang DuongAnh Vu Trinhvuta@vnu.edu.vnXuan Thang Vuthang.vu85@gmail.com2018-12-13T07:49:45Z2018-12-19T05:08:47Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3250This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32502018-12-13T07:49:45ZCache-aided Full Duplex: Delivery Time Analysis
and OptimizationEdge caching has received much attention as a
promising technique to overcome the stringent latency and data
hungry challenges in the future generation wireless networks.
Meanwhile, full duplex (FD) transmission can potentially double
the spectral efficiency by allowing a node to receive and transmit
simultaneously. In this paper, we investigate the delivery time
performance of a cache-aided FD system, in which an edge
node, operates in FD mode, serves users via wireless channels
and is equipped with a cache memory. Firstly, we derive a
closed-form expression for the average delivery time by taking
into account the uncertainties of both backhaul and access
wireless channels. The derived analysis allows the examination
of the impact of key parameters, e.g., cache size and transmit
power. Secondly, a power optimization problem is formulated
to minimize the average delivery time. To deal with the nonconvexity
of the formulated problem, we propose an iterative
optimization algorithm by using the bisection method. Finally,
numerical results are presented to demonstrate the effectiveness
of the proposed algorithm.Xuan Thang Vuthang.vu85@gmail.comAnh Vu Trinhvuta@vnu.edu.vnSymeon ChatzinotasChatzinotas@gmail.comBjörn OtterstenOttersten@gmail.com2017-12-26T07:00:28Z2017-12-26T07:00:28Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2796This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/27962017-12-26T07:00:28ZEnhancing WiFi based Indoor Positioning by Modeling Measurement Data with GMMAbstract—Recently, indoor positioning has been investigated by many research groups. Several proposals for indoor positioning have been developed over the last decades, amongst them, WiFi fingerprinting based is considered as the most promissing approach. However, many challenges are still remained for improving the accuracy of indoor mobile object localization. This paper presents a novel approach for enhancement of WiFi fingerprinting based indoor positioning by using Gaussian Mixture Model (GMM) to model the measured Received Signal Strength Index (RSSI) distributions. Since the measured data
varies due to obstacles in indoor environments as well as user directions, the proposed approach is able to model the data distribution more precise than the previous popular approach which utilizes single Gaussian. Simulation results demonstrate the effectiveness of the proposed approach compared to the others.Manh Kha Hoangkhamh@gmail.comThi Hang Duongduongthihang.haui@gmail.comTrung Kien Vukienvt@gmail.comAnh Vu Trinhvuta@vnu.edu.vn2017-12-26T06:14:07Z2018-01-05T07:15:30Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2786This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/27862017-12-26T06:14:07ZĐIỀU KHIỂN CÔNG SUẤT ĐƯỜNG XUỐNG CHO DUNG LƯỢNG NGƯỜI DÙNG ĐỒNG ĐỀU TRONG HỆ THỐNG MASSIVE MIMO ĐƠN TẾ BÀOBài báo đề xuất kỹ thuật điều khiển công suất đường xuống nhằm làm cho dung lượng người dùng đồng đều trong hệ thống Massive MIMO đơn tế bào sau khi xây dựng các biểu thức tính toán phẩm chất kênh. Khác với những nghiên cứu về điều khiển công suất phức tạp nhằm tối ưu hệ thống với những điều kiện ràng buộc khác nhau, bài báo này đề xuất một kỹ thuật đơn giản chỉ nhắm đến mục tiêu là cung cấp dung lượng người dùng bình đẳng khi ràng buộc công suất tổng tại trạm cơ sở không đổi, đó là chỉ cần phân công suất tỷ lệ nghịch với suy giảm đường truyền. Ngoài ra một số liên hệ cơ bản khi thiết kế hệ thống cũng được rút ra. Kết quả mô phỏng cho thấy hiệu quả của phương pháp đề xuất này.Anh Vu Trinhvuta@vnu.edu.vnThi Quynh Trang Phamtrangptq@gmail.comTrung Nghia Phungptnghia@ictu.edu.vn2017-10-29T03:16:53Z2017-12-17T08:24:10Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2587This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/25872017-10-29T03:16:53ZJoint Exploration Model based Light Field Image Coding: A Comparative StudyThe recent light field imaging technology has been attracting a lot of interests due to its potential applications in a large number of areas including Virtual Reality, Augmented Reality (VR/AR), Teleconferencing, and E-learning. Light Field (LF) data is able to provide rich visual information such as scene rendering with changes in depth of field, viewpoint, and focal length. However, Light Field data usually associates to a critical problem - the massive data. Therefore, compressing LF data is one of the main challenges in LF research. In this context, we present in this paper a comparative study for compressing LF data with not only the widely used image/video coding standards, such as JPEG-2000, H.264/AVC, HEVC and Google/VP9 but also with the most recent image/video coding solution, the Joint Exploration Model. In addition, this paper also proposes a LF image coding flow, which can be used as a benchmark for future LF compression evaluation. Finally, the compression efficiency of these coding solutions is thoroughly compared throughout a rich set of test conditions.Cong Huy Phihuypc@ptit.edu.vnStuart PerryStuart.Perry@uts.edu.auAnh Vu Trinhvuta@vnu.edu.vnVan Xiem Hoangxiemhoang@vnu.edu.vn2017-06-09T11:27:50Z2017-06-09T11:27:50Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2489This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/24892017-06-09T11:27:50ZSpectral-Efficient Model for Multiuser Massive MIMO: Exploiting User VelocityThe employment of a massive number of antennas
in multiple-input multiple-output systems, known as massive MIMO, has drawn a new horizon for future communications systems to support a very large number of users. However, the actual number of active users in massive MIMO are limited by pilots training via the coherence time of the communication channel which is inversely proportional to the user velocity. The
current model applies this coherence time for every user to design multiuser massive MIMO, which might result in a suboptimal solution since the users usually move at different speeds in practice. In this paper, we investigate multiuser massive MIMO by taking into consideration the differences in user velocities.
In particular, two multiuser models are proposed to maximize the per-user spectral efficiency and the number of served users, respectively. System capacity of the proposed models is provided in analytical expression. Finally, numerical results demonstrate the advantages of our proposed models compared with the reference model.Xuan Thang Vuthangvx85@gmail.comAnh Vu Trinhvuta@vnu.edu.vnSymeon ChatzinotasChatzinotas@gmail.comBjörn OtterstenOttersten@gmail.com2016-12-25T17:06:03Z2016-12-25T17:06:03Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2019This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/20192016-12-25T17:06:03ZHiệu năng của hệ thống tìm phương sử dụng anten không tâm pha bất đối xứngBài báo thực hiện việc đánh giá hiệu năng của hệ thống tìm phương sử dụng anten không tâm pha có cấu trúc bất đối xứng Asym-AWPC (Asymmetric - Antenna without Phase Center). Đây là cấu trúc anten có giản đồ pha là hàm phi tuyến đã được nhóm nghiên cứu đề xuất và tối ưu hóa về kích thước trong các công trình công bố gần đây. Khi kết hợp Asym-AWPC với thuật toán phân lớp nhiều tín hiệu MUSIC (MUltiple Signal Classification), hệ thống tìm phương này có khả năng ước lượng cùng lúc nhiều nguồn tín hiệu với độ phân giải cao trong toàn bộ không gian 360O ngay cả khi số nguồn tín hiệu đến lớn hơn số phần tử anten. Hiệu năng của hệ thống được đánh giá thông qua lỗi ước lượng góc và được so sánh với hệ thống sử dụng cấu trúc mảng tròn cách đều UCA (Uniform Circular Array), là cấu trúc được sử dụng nhiều trong thực tế. Dựa trên các kết quả mô phỏng, có thể thấy rằng hệ thống đề xuất có hiệu năng tốt hơn nhiều hệ thống sử dụng UCA với cùng số phần tử anten, đặc biệt trong các trường hợp tỷ số công suất tín hiệu trên công suất tạp âm SNR (Signal to Noise Ratio) thấp, khoảng cách giữa các góc của các nguồn tín hiệu đến nhỏ (độ phân giải cao), cũng như số mẫu tín hiệu thu thập tại mỗi phần tử anten ít.Thi Thuy Quynh Tranquynhttt@vnu.edu.vnAnh Vu Trinhvuta@vnu.edu.vnMinh Tuan Trantm_tuan@mic.gov.vnAnh Phanphananh@rev.org.vn2016-12-05T04:15:40Z2016-12-05T04:15:40Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2099This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/20992016-12-05T04:15:40ZA simple diagram for data transmission using Manchester codeThe paper proposes a simple diagram for data
transmission on the frequency of 2.4GHz based on the
Manchester code. Unlike the classical methods, the receiver
usually performs some feedback loops to stabilize the gain to control the sampling at exact position (timing) of the symbol or to synchronize and track frequency. The proposed diagram only uses a cut-off signal to detect data directly without any feedback loops. Although it is simple, the proposed diagram still obtains high stable operation and wide input dynamic range. The experiment was tested by transmitting a 64kbit image file through an embedded FPGA system. Due to the use of Manchester code, then the cost of the proposed method depends only on the bandwidth. Furthermore, the proposed diagram is more suitable for indoor transmission applications and transmitting high-speed data by using Ultra Wide Band (UWB) pulsesAnh Vu Trinhvuta@vnu.edu.vnVan Thanh Phamphamvanthanh1209@gmail.com2016-05-30T07:00:20Z2016-05-30T07:01:51Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/846This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/8462016-05-30T07:00:20ZHiệu năng của hệ thống tìm phương sử dụng anten không tâm pha bất đối xứngThi Thuy Quynh Tranquynhttt@vnu.edu.vnAnh Vu Trinhvuta@vnu.edu.vnMinh Tuan TranAnh Phanphananh@vnu.edu.vn2016-05-28T04:01:40Z2016-05-28T04:01:40Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1709This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/17092016-05-28T04:01:40ZSuccessive pilot contamination elimination in multiantenna multicell networksThis paper addresses the problem of channel estimation in time-division duplex (TDD) multicell cellular systems, where the performance of such systems is usually bounded by a bottleneck due to pilot contamination. We propose two channel estimation schemes that completely remove pilot contamination. The exact closed-form expression for average mean square error (MSE) of the proposed estimators is derived. More importantly, our proposed estimators do not need to know the second-order statistics of either desired user channels or interfering user channels. Finally, simulated results confirm gains over existing channel estimation schemes.Xuan Thang Vuthang.vu85@gmail.comAnh Vu Trinhvuta@vnu.edu.vnTony QS QuekT.Quek@gmail.com2016-05-26T06:41:22Z2016-05-26T06:42:14Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1652This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/16522016-05-26T06:41:22ZA Solution to Enhance the Efficiency of the High Power S Band LDMOS Amplifier for Microwave Power Transmission and Wireless CommunicationDinh The Anh NguyenHoang Giang BachAnh Vu Trinhvuta@vnu.edu.vnGia Duong Bachduongbg@vnu.edu.vn2016-05-26T06:39:04Z2016-05-26T06:40:57Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1641This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/16412016-05-26T06:39:04ZNon-Coherent IR-UWB Receiver Front-End for High-Precision Ranging and LocalizationAnh Vu Trinhvuta@vnu.edu.vnGia Duong Bachduongbg@vnu.edu.vnT.S Lande2016-05-26T02:37:24Z2016-05-26T02:38:13Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/845This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/8452016-05-26T02:37:24ZDesign of a Simple OFDM-IF Transceiver on FPGAThi Thuy Quynh Tranquynhttt@vnu.edu.vnAnh Vu Trinhvuta@vnu.edu.vnHung Hai Hoang2015-12-22T07:45:19Z2015-12-22T07:46:10Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1440This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/14402015-12-22T07:45:19ZSuccessive Pilot Contamination Elimination in Multi-antenna Multi-cell NetworksXuan Thang VuAnh Vu Trinhvuta@vnu.edu.vnTony Q.S. Quek2015-12-22T07:43:17Z2015-12-22T07:44:21Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1441This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/14412015-12-22T07:43:17ZDesign and Implementation of the Alamouti-OFDM system based on FPGAVan Tai TranVan Huy NguyenAnh Vu Trinhvuta@vnu.edu.vnXuan Thang Vu2015-12-03T06:50:57Z2015-12-03T06:51:48Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/1401This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/14012015-12-03T06:50:57ZSimple Channel Estimation Techniques Based on Pilot-Assistance for STBC-Based MIMO-OFDM SystemsDuc Tan Trantantd@vnu.edu.vnDuc Tuyen TaAnh Vu Trinhvuta@vnu.edu.vnHuu Tue Huynh2015-03-17T09:48:26Z2017-02-05T09:59:25Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/408This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/4082015-03-17T09:48:26ZAntenna selection in rank-deficient MIMO systemsIn a rank-deficient MxN MIMO system, the number of non-zero eigen-modes is smaller than min (M,N). In such a system, it is desirable to be able to identify then eliminate the most dasiainactivepsila antennas or equivalently to select the most dasiaactivepsila antennas for operation. In this paper we use the incremental algorithm for the successive selection technique for receive antenna selection applied to a rank-deficient indoor MIMO link transmitting through a small window between two rooms. It is shown that there is a close correspondence between the rank of the ill-conditioned MIMO channel and the minimum number of receive antennas that can be selected for a given small reduction in capacity.Xuan Thang Vuthang.vu85@gmail.comDinh Thong NguyenAnh Vu Trinhvuta@vnu.edu.vn2015-03-17T09:44:20Z2017-02-05T10:00:04Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/407This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/4072015-03-17T09:44:20ZAn finite-state Markov channel model for ACM scheme in WiMAXThe paper derives a more accurate upper bound for BER for M-QAM than is currently used in the literature. This allows a more thorough analysis of the power adaptation to fading conditions for optimization of spectral efficiency. By taking into account the effect of error coding gain on power adaptation, a 7-state FSMC model for the implementation of the adaptive modulation and coding scheme in WiMAX is proposed.Xuan Thang Vuthang.vu85@gmail.comDinh Thong NguyenAnh Vu Trinhvuta@vnu.edu.vn2015-03-17T08:43:42Z2017-01-17T02:50:17Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/406This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/4062015-03-17T08:43:42Z16-QAM Transmitter and Receiver Design Based on FPGAThe FPGA technology has been playing a considerable role in portable and mobile communication. This is due to the features of flexibility, accuracy and configurability in designing and implementation. The paper presents a complete design for a 16-QAM transmitter and receiver based on the Virtex4 FPGA Kit. The implemented system can be applied in particle. Based on the principles of carrier synchronization, time synchronization, core tools for phase-different detecting as well as adaptive equalization processing in System Generator (a software of Xilinx), the authors have designed a complete baseband IF 16-QAM system, in which the baseband signal is upconverted into IF frequency (up to 12MHz) at the transmitter and then is downconverted at the receiver. After timing synchronizing, the adaptive equalizing and phase recovering, the received baseband signal is displayed in the oscilloscope's screen. These accurate experiments conducted in Virtex 4 FPGA board kit have shown a promising foundation for developing coding, algorithms in 16-QAM modulation scheme.Xuan Thang Vuthang.vu85@gmail.comDuc Anh NguyenAnh Vu Trinhvuta@vnu.edu.vn2013-01-23T08:19:28Z2013-06-29T04:18:51Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/126This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/1262013-01-23T08:19:28ZThe Application of a Multibeam Antenna for 4GThere are various antenna schemes which can be used to increase the throughput of the 4th mobile generation (4G) networks such as antenna diversity, beamforming, spatial multiplexing and MIMO (Multiple Input Multiple Output) 1. With the above antenna schemes OFDMA (Orthogonal Frequency Division Multiple Access) is a suitable selection for 4G. This paper proposes a multibeam antenna combining OFDMA for the next generation mobile communications. Analysis and simulation show that this kind of antenna is comparable to MIMO scheme and can be applied to 4G.Cao Quyen Tranquyentc@vnu.edu.vnAnh Vu Trinhvuta@vnu.edu.vn