• Title/Summary/Keyword: user-multiplexing

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English Performance of MIMO-OFDM Combing Bemaformer with Space-time Decoder in Multiuser Environments (다중 사용자 환경에서 빔 형성기와 결합된 Space-Time decoder을 가진 MIMO-OFDM 시스템의 성능)

  • Kim Chan-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.8A
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    • pp.775-783
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    • 2006
  • In this paper, the new technique combining beamforming with space-time coding is proposed for an orthogonal frequency division multiplexing(OFDM) system with multi-input multi-output(MIMO). When MIMO-OFDM system is employing Nt(the number of transmitterantenna) beamfomers and one S-T decoder at Nr receiver antennas, Nt signals removed CCI are outputted at the beamformer and then diversity gain can be got through space-time decoding. As the proposed technique can reduce cochannel interference and get diversity gain in the multi-user environment, the performance of MIMO-OFDM system is very improved. BER performance improvement and convergence behavior of the proposed approach are investigated through computer simulation by applying it to MIMO-OFDM system in the multi-user environment.

Efficient Transmission Mode Selection Scheme for MIMO-based WLANs

  • Thapa, Anup;Kwak, Kyung Sup;Shin, Seokjoo
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.7
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    • pp.2365-2382
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    • 2014
  • While single-user spatial multiplexing multiple-input multiple-output (SU-MIMO) allows spatially multiplexed data streams to be transmitted to one node at a time, multi-user spatial multiplexing MIMO (MU-MIMO) enables the simultaneous transmission to multiple nodes. However, if the transmission time required to send packets to each node varies considerably, MU-MIMO may fail to utilize the available MIMO capacity to its full potential. The transmission time typically depends upon two factors: the link quality of the selected channel and the data length (packet size). To utilize the cumulative capacity of multiple channels in MIMO applications, the assignment of channels to each node should be controlled according to the measured channel quality or the transmission queue status of the node.A MAC protocol design that can switch between MU-MIMO and multiple SU-MIMO transmissions by considering the channel quality and queue status information prior to the actual data transmission (i.e., by exchanging control packets between transmitter and receiver pairs) could address such issues in a simple but in attractive way. In this study, we propose a new MAC protocol that is capable of performing such switching and thereby improve the system performance of very high throughput WLANs. The detailed performance analysis demonstrates that greater benefits can be obtained using the proposed scheme, as compared to conventional MU-MIMO transmission schemes.

Reduced Complexity Scheduling Method with MIMO Interference Alignment for Mutually Interfering Broadcast Channels (상호 간섭 Broadcast 채널을 위한 MIMO 간섭 정렬을 이용한 복잡도를 줄인 스케쥴링)

  • Park, Hae-Wook;Park, Seok-Hwan;Sung, Hak-Jea;Lee, In-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.8A
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    • pp.601-611
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    • 2012
  • In this paper, we first study the spatial multiplexing gain for the 3-cell interfering broadcast channels (IFBC) where all base stations and mobile users are equipped with multiple antennas. Then, we present the IA scheme in conjunction with user selection which outperforms the TDMA technique in the IFBC environment. The optimal scheduling method utilizes multiuser diversity to achieve a significant fraction of sum capacity by using an exhaustive search algorithm. To reduce the computational complexity, a suboptimal scheduling method is proposed based on a coordinate ascent approach.

Multimodal Interaction on Automultiscopic Content with Mobile Surface Haptics

  • Kim, Jin Ryong;Shin, Seunghyup;Choi, Seungho;Yoo, Yeonwoo
    • ETRI Journal
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    • v.38 no.6
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    • pp.1085-1094
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    • 2016
  • In this work, we present interactive automultiscopic content with mobile surface haptics for multimodal interaction. Our system consists of a 40-view automultiscopic display and a tablet supporting surface haptics in an immersive room. Animated graphics are projected onto the walls of the room. The 40-view automultiscopic display is placed at the center of the front wall. The haptic tablet is installed at the mobile station to enable the user to interact with the tablet. The 40-view real-time rendering and multiplexing technology is applied by establishing virtual cameras in the convergence layout. Surface haptics rendering is synchronized with three-dimensional (3D) objects on the display for real-time haptic interaction. We conduct an experiment to evaluate user experiences of the proposed system. The results demonstrate that the system's multimodal interaction provides positive user experiences of immersion, control, user interface intuitiveness, and 3D effects.

A Memory Configuration Method for Virtual Machine Based on User Preference in Distributed Cloud

  • Liu, Shukun;Jia, Weijia;Pan, Xianmin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.11
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    • pp.5234-5251
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    • 2018
  • It is well-known that virtualization technology can bring many benefits not only to users but also to service providers. From the view of system security and resource utility, higher resource sharing degree and higher system reliability can be obtained by the introduction of virtualization technology in distributed cloud. The small size time-sharing multiplexing technology which is based on virtual machine in distributed cloud platform can enhance the resource utilization effectively by server consolidation. In this paper, the concept of memory block and user satisfaction is redefined combined with user requirements. According to the unbalanced memory resource states and user preference requirements in multi-virtual machine environments, a model of proper memory resource allocation is proposed combined with memory block and user satisfaction, and at the same time a memory optimization allocation algorithm is proposed which is based on virtual memory block, makespan and user satisfaction under the premise of an orderly physical nodes states also. In the algorithm, a memory optimal problem can be transformed into a resource workload balance problem. All the virtual machine tasks are simulated in Cloudsim platform. And the experimental results show that the problem of virtual machine memory resource allocation can be solved flexibly and efficiently.

Relay-assisted Multiple Access Channel Protocol for Cooperative Diversity

  • Kim, Dong-Hyun;Kim, Gil;Lee, Kwang-Bok
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.1C
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    • pp.1-8
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    • 2009
  • Cooperative diversity is a novel technique to improve diversity gains, capacity gains, and energy saving. This technique involves multiple terminals sharing resources in order to build a virtual antenna array in a distributed fashion. In this paper, we propose a multi-user cooperative diversity protocol called Relay-assisted Multiple Access Channel(R-MAC) that allows multiple source terminals to transmit their signals simultaneously and the relay terminal forwards the aggregated signal received from the source terminals to the destination terminal. The proposed protocol converts the distributed antenna channels into an effective MIMO channel by exploiting a relay, increasing both diversity gain and system throughput. We investigate the performance of the proposed protocol in terms of outage probability and diversity-multiplexing tradeoff where we assume block fading channel environment. Our simulation results show that the proposed protocol outperforms direct transmission in the high spectral efficiency regime where the conventional cooperative diversity protocols cannot outperform direct transmission.

Analysis of Spatial Multiplexing Gain in a Two-cell MIMO Environment with Coordinated Base Stations (협력 기지국을 가진 2-셀 다중 안테나 환경에서 공간적 다중화 이득 분석)

  • Kim, Jae-Sin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.5C
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    • pp.376-383
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    • 2012
  • In this paper, we provide a general expression of spatial multiplexing gain (SMG) for two mutually interfering multiple-input multiple-output (MIMO) broadcast channels, referred to as MIMO-IBC, when some of user messages are made available to base stations through a common noiseless backbone line. The MIMO-IBC has two base stations and multiple users, each equipped with multiple antennas, where independent messages are transmitted over fixed channels. From the derived results, we observe the variation of the SMG with respect to the presence of a coordination as well as various antenna distributions, and compare the derived result to the SMG of the case with full cooperation among users.

A Joint Power Allocation and Scheduling Algorithm for CDMA-based High-rate Packet Data Systems (CDMA기반 고속 패킷 데이터 전송 시스템을 위한 전력제어가 결합된 스케쥴링 알고리즘)

  • Koo In-Soo;Kim Ki-Seon
    • Journal of Internet Computing and Services
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    • v.7 no.3
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    • pp.41-51
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    • 2006
  • In the case of CDMA-based packet data systems such as 1xEV-DO which are designed to support high rate services, BSs transmit data packets with a maximum power based on time multiplexing mode such that only one user can be serviced at a time. In this paper, we propose a joint power allocation and scheduling algorithm for 1xEV-DO-like systems in which we adopt a code division multiplexing (CDM) transmission method in the downlink common channel in order to utilize channel orthogonality such that we can serve more than one user at a time slot especially when there exist remaining resources after serving the firstly selected user by the scheduler. Simulation results demonstrate that the proposed scheme can improve the performances of conventional schemes such as the maximum rate and the proportional fair algorithms.

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Subcarrier Allocation Algorithm with Simple CSI for Multiuser OFDM System (다중 사용자 OFDM 시스템에서 간략화된 채널 정보를 이용한 부반송파 할당 알고리즘)

  • Yang, Jun-Seok;Park, Sang-Kyu
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.3
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    • pp.229-235
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    • 2010
  • The Orthogonal Frequency Division Multiplexing(OFDM) has been strongly recommended as a transmission technique in order to satisfy requests of high speed and high quality multimedia information. This paper considers resource allocation algorithm which supports the user Quality of Service(QoS) for multi-user OFDM system with simple CSI (Channel State Information) structure. After users eligible for services and the number of subcarrier are determined by minimum request data rate and average channel gain, subcarriers are allocated to increase total transmission rates. Although ideal CSI is not reported to base station, compared to conventional algorithm, we have obtained better result with simple CSI structure.

A New Diversity Technique for multi-user OFDM (다중 사용자 OFDM 시스템에서 다이버시티를 향상시키기 위한 새로운 기법)

  • Heo, Ji-Haeng;Min, Hyun-Kee;Kim, Hyung-Jong;Hong, Dae-Sik
    • Proceedings of the IEEK Conference
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    • 2008.06a
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    • pp.217-218
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    • 2008
  • A new diversity technique is proposed for multi-user single-input single-output (SISO) orthogonal frequency division multiplexing (OFDM) uplink system. Each user transmit a symbol using frequency band of all users that are active in the uplink. In addition, a receiver detect each signal using maximum likelihood (ML) method. Simulation results show that the proposed technique improves a diversity order without an additional bandwidth and a loss of data rate.

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