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LTE作为一个革命性的宽带移动通信标准,从频域、空域等维度对空间信道进行了深度挖掘,同时采用了自适应系统设计和简洁全IP的扁平网络架构,提供了强大的时频资源。面对极度灵活的系统,在如何高效地利用这些时频资源、如何实现真正的同频组网等方面仍存在挑战,需不断努力才能充分发挥LTE技术的预期潜力。本文分析了3GPP长期演进（LTE）标准的技术创新点以及研发面临的挑战。 相似文献
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基于TD-LTE系统的自适应调度技术研究 总被引：1，自引：0，他引：1
随着移动通信技术的飞速发展,LTE技术作为移动通信系统的主要演进方向,以其高速率、低时延的特点,越来越受到世界各大主流运营商和设备厂商的广泛关注。由于OFDM和MI-MO等先进技术的引入,使LTE系统的资源分配具有很大的灵活性,但是,面对这样灵活的系统,如何高效地利用这些时频资源,有效提高LTE系统的频谱效率,还有很多... 相似文献
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Alexandre Ragaleux Sbastien Baey Anne Fladenmuller 《Wireless Communications and Mobile Computing》2016,16(17):3089-3103
This paper addresses the downlink resource allocation problem in pre‐5G (LTE‐B) networks. At each time slot, the problem is to share the radio resources between users in order to maximize a given objective function. We expressed this problem considering the LTE standard constraints, which are rarely considered in the literature. Mainly, for any given user, the base station is constrained to transmit with a single modulation and coding scheme. We show that this problem is non‐deterministic polynomial‐time hard, and therefore, we propose a generic approximation algorithm that covers a large variety of objectives. This algorithm is composed of three routines that enable an effective resource sharing procedure. The first routine computes a solution for a relaxation of our main problem, while the second routine selects the most suitable modulation and coding scheme for each user. Finally, the last routine effectively distributes the unallocated resources. For the max rate policy, simulation results show that our algorithm outperforms other existing algorithms in terms of capacity and remains close to the optimal. Under the proportional fairness policy, our solution also provides a very good fairness while maintaining a near‐optimal capacity. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Tae Chul Hong Kunseok Kang Bon‐Jun Ku Dae‐Ig Chang 《International Journal of Satellite Communications and Networking》2017,35(1):3-15
For the successful deployment of the long term evolution (LTE)‐based mobile satellite service, the price of a user terminal is one of the major factors. A user terminal for the LTE‐based satellite communication needs to be implemented with a similar hardware size that is used for a terrestrial LTE user terminal. However, for quality of service provision, the satellite user terminal needs a larger size of memories than the terrestrial terminal does. This is very evident by considering that the N‐channel stop and wait hybrid automatic repeat request requires proportionally increasing memory size by the propagation delay, resulting in unmanageable amount of memories in the satellite system. To resolve this problem, we propose an efficient memory management method at the user terminal when the size of memory is insufficient. The simulation results in this paper reveal that the proposed method can increase the throughput about 20.7% when a user terminal is operated under very low throughput condition with an insufficient memory size, compared with the case without memory management scheme. In addition, we show that the additional throughput gain can be obtained by the packet scheduling using the information of receiver memory status. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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严秋实 《电信工程技术与标准化》2010,23(5):78-80
上行接入为用户设备UE（UserEquipment）接入网络提供上行支撑,是移动通信不可或缺的重要组成部分。优秀、高效的上行接入技术可以大大提高上行链路的频谱效率,增加系统容量,扩大覆盖范围,最大化的减小时延。本文通过对LTE（LongTimeEvolution）标准中上行接入技术的研究,较为全面地对LTE环境下上行接入进行了分析和介绍。 相似文献
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中继技术能够对原有基站进行覆盖增强,同时OFDMA技术是下一代移动通信的主要多址方式,因而研究设计OFDMA技术约束下的中继方案,具有非常现实的意义.以LTE物理层帧结构为基础,针对OFDMA调制系统的中继实现方式进行了深入分析,结合OFDMA系统灵活的时频资源分配特点,提出针对OFDMA的多跳/单跳资源分配方法,最后,还提出一种针对FDD模式的OFDMA中继实现方案,对认为中继只能用于TDD系统的传统观念进行了前沿性的拓展. 相似文献
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Tae Chul Hong Sungmoon Yeo Sooyoung Kim Kun‐Seok Kang Bon‐Jun Ku 《International Journal of Satellite Communications and Networking》2012,30(5):221-234
The adaptive modulation and coding (AMC) scheme is mandatory for modern wireless communication systems to overcome inevitable channel impairments. Many of the limitations using AMC are due to the long round‐trip delay of a satellite system. This paper proposes an efficient AMC scheme with power control and symbol interleaving that can be effectively applied to satellite systems. In particular, we focus on mobile satellite systems that have maximum compatibility in a Long Term Evolution system. Simulations reveal that the proposed scheme can provide a maximum 10.2% increase of average beam spectral efficiency and a maximum of 8‐dB power gain compared with a conventional AMC scheme. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Tae Chul Hong Kun‐Seok Kang Bon‐Jun Ku Do‐Soeb Ahn 《International Journal of Satellite Communications and Networking》2014,32(5):377-392
Hybrid automatic repeat request (HARQ) and automatic repeat request (ARQ) of the terrestrial long‐term evolution (LTE) system are designed considering the very short propagation delay of terrestrial environment. Therefore, when HARQ and ARQ are applied to the LTE‐based mobile satellite communication system, the inefficiency is caused by the long propagation delay of satellite environment. This paper proposes the interaction method between HARQ and ARQ for the decrease of inefficiency in the LTE‐based mobile satellite communication system. The existing concept of layered architecture about HARQ and ARQ is also maintained in our interaction method. Simulation results reveal that our proposed scheme can provide the larger spectrum efficiency than that of the non‐interaction scheme in all environments. The performance improvement can be up to 2.04 times through the interaction method. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Itzik Kitroser Yehuda Ben‐Shimol 《Wireless Communications and Mobile Computing》2016,16(14):2116-2130
We examine a new problem called the Zone Selection Problem (ZSP) in wireless Orthogonal Frequency‐Division Multiple Access (OFDMA)‐based systems. We consider the case where the mobile station (MS) informs the base station of its preferences regarding possible working modes supported by the system. In Worldwide Interoperability for Microwave Access (WiMAX) systems, which are used as a practical reference system for constraints and specific modes of operations, each working mode must be assigned at a different time interval called a Zone. Such zone may, in the downlink subframe, define a specific transmission scheme, which can be either single‐input single‐output or one of the multiple‐in multiple‐out (MIMO) modes supported by the system. We define ZSP as a problem where the base station assigns MSs to zones in a way that optimizes the system utilization (in terms of resource usage) while trying to satisfy the preferences of the users as much as possible. This makes ZSP a bi‐objective optimization problem. We derive assignment costs from physical channel models that integrate specific MIMO schemes and channel conditions. We provide an exact solution to ZSP by using a combinatorial optimization abstraction. We propose a simplified and practical mode ranking approach that enables the MS to define its preferences regarding operation in the optional MIMO modes in the system. We prove that ZSP is NP‐hard and describe two heuristic solutions: a greedy approach and a local search approach. Simulation results show the performance of the exact algorithms on a realistic WiMAX system assumptions and present the trade‐off between the user preferences and system preferences. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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未来的移动通信系统LTE的下行链路将广泛采用MIMO-OFDM技术。基于MIMO-OFDM系统的表达式和信道模型,以及Zadoff-Chu序列,提出了一种等周期的伪叠加Zadoff-Chu序列的集中式和分布式MIMO同步算法,并进行了仿真。仿真结果表明该算法能够准确地进行符号时间同步,验证了所提出符号同步算法的有效性。 相似文献
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文章介绍了LTE体系结构及小区内的RRM,提出具有认知特性的B3GLTE系统的增强型RRM的框架,阐述了其管理功能模块和上下文获取机制。仿真表明,LTE网络环境下认知RRM方案能大大提高系统性能和网络的自适应性。 相似文献
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上行接入为用户设备（UE,User Equipment）接入网络提供上行支撑,是移动通信不可或缺的重要组成部分。优秀、高效的上行接入技术可以大大提高上行链路的频谱效率,增加系统容量,扩大覆盖范围,最大化的减小时延。本文通过长期演进对（LTE,Long Time Evolution）标准中上行接入技术的研究,较为全面地对LTE环境下上行接入进行了分析和介绍。 相似文献
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LTE中MIMO技术面临的挑战及其测试 总被引：1，自引：0，他引：1
分析了3GPP长期演进（LTE）标准中多输入多输出（MIMO）技术面临的挑战和相应的测试方法。LTE的MIMO技术引入了空间维度,但是空间维度的利用在现阶段仍然面临很大挑战,如方向控制信道受限,各种MIMO模式的应用场景不明确及各种MIMO模式间的切换等。针对各项挑战和不确定性,需要用大量的实验来验证和促进MIMO技术的发展。讨论了MIMO技术的室内测试方法和室外测试方法。 相似文献
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移动WiMAX系统的技术分析及对TD-SCDMA的发展启示 总被引：1，自引：0，他引：1
本文首先对移动WiMAX的主要技术进行分析,主要包括MIMO技术、OFDM／OFDMA技术及越区切换等,然后阐述了移动WiMAX目前的发展状况,就其对我NTD—SCDMA的发展提供的借鉴经验进行介绍。 相似文献
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文章在阐述LTE中MIMO无线系统通信技术的特点及需研究的问题基础上,尝试探讨了MIMO技术在LTE中的具体应用挑战,以期为深入研究MIMO无线传输技术提供参考。 相似文献