摘要 :
TDD (Time Division Duplex) is one of the two duplex modes. TD-SCDMA (Time Division Synchronous CDMA) is the first TDD-based cellular mobile system which is commercialized in wide area and large scale and TD-SCDMA is also the first...
展开
TDD (Time Division Duplex) is one of the two duplex modes. TD-SCDMA (Time Division Synchronous CDMA) is the first TDD-based cellular mobile system which is commercialized in wide area and large scale and TD-SCDMA is also the first cellular mobile system which adopted smart antenna technology (also called as beamforming). As the long term evolution of TD-SCDMA, TD-LTE(A) (Time Division-Long Term Evolution, and TD-LTE Advanced) introduced OFDM (Orthogonal Frequency Division Multiplexing) and enhanced smart antenna technology together with MIMO (Multiple Input Multiple Output), which are adopted by LTE FDD (Frequency Division Duplex) either. It is indicated that TD-SCDMA and TD-LTE(A) have opened a sustainable utilization era of TDD and smart antenna technologies in the wireless mobile communication. This paper aims to present a systematic introduction to TDD-based mobile communications from TD-SCDMA to TD-LTE and beyond, with particular focuses on TDD key technologies, principles of TDD cellular mobile systems, TDD evolution path, and future TDD 5G directions. The comparisons between TDD and FDD are also included. We hope that this paper will provide a comprehensive overview of TDD technology upgrade and its standard evolution, and serve as a valuable reference for research on 5G mobile communication systems. It is believed that TDD will play more important role in 5G.
收起
摘要 :
This paper introduces mechanisms and algorithms for managing efficiently the resources of Time-Division Long Term Evolution (TD-LTE) networks in a flexible manner enabling (i) dynamic frame alternation at each evolved Node B (eNB)...
展开
This paper introduces mechanisms and algorithms for managing efficiently the resources of Time-Division Long Term Evolution (TD-LTE) networks in a flexible manner enabling (i) dynamic frame alternation at each evolved Node B (eNB) and (ii) forming virtual cells, which allow diverse resource utilization to users residing within regions that can utilize resources from multiple eNBs. Our approach leverages the benefits of Software Defined Network (SDN) paradigm for monitoring network resource utilization and allowing applications or services to request resources. The resources requested by the applications or services can be allocated on-demand by adjusting the Time Division Duplex (TDD) frames in different regions of the geographical area being considered. This can be accomplished by creating virtual cells in the overlapping regions that can customize service for the residing users. A simulation study has been carried out to elaborate the benefits of this approach and the performance enhancements in comparison with the conventional TD-LTE configurations are presented. The results indicate significant performance gains of around 30%-35% considering both UL/DL directions respectively. (C) 2015 Elsevier B.V. All rights reserved.
收起
摘要 :
A radio system is classified into SISO(Single input single output),SIMO,MISO and MIMO. In radio the SISO system uses an antenna in the transmitter and receiver. The SISO systems are typically less complex than the MIMO(Multiple in...
展开
A radio system is classified into SISO(Single input single output),SIMO,MISO and MIMO. In radio the SISO system uses an antenna in the transmitter and receiver. The SISO systems are typically less complex than the MIMO(Multiple input Multiple Output)systems. In this paper we are presenting a 2 × 2 MIMO OTA measurement system. FPGAs are used for applications like signal processing, image processing, communications and control systems. The SDR are radios that provide software control on a variety of modulation techniques In this system real-time FPGA(Field programmable gate arrays) based software-defined radio are used. Vestigial signal transceivers are used for the signal generation and channel emulation. Many different MIMO OTA test methods have been proposed. Wireless communication industry groups such as Third generation partnership project (3GPP) and international association for wireless telecommunication are working on the standardization of the two-stage MIMO OTA. The test equipment we are using is the (TD-LTE) duplex scheme.
收起
摘要 :
It has been an enigma for the communities of practice and academia in the field of standards as to why, when the capabilities of a technology are not much different or even superior to those of their competitors, only some standar...
展开
It has been an enigma for the communities of practice and academia in the field of standards as to why, when the capabilities of a technology are not much different or even superior to those of their competitors, only some standards lead to commercial success. Previous literature indicates that a standard needs organisational support and legitimacy amongst audiences, including distributors, influenced by network connectivity and configuration. Using a social network analysis, this paper visualises and compares the networks of wireless broadband and time domain-long-term evolution deployment in the global market. The results show that the presence of a few key sponsors with financial resources and a large installed base is more important than the size of the network. Consequently, we draw some implications for sustainable deployment of future standards.
收起
摘要 :
Due to the time-variant channel, outdated channel state information (CSI) largely reduce the performance of double codebook beamforming system. This paper studies the two codebooks independently and proposes an adaptive feedback p...
展开
Due to the time-variant channel, outdated channel state information (CSI) largely reduce the performance of double codebook beamforming system. This paper studies the two codebooks independently and proposes an adaptive feedback period adjustment Strategy for long-term codebook and a prediction estimation algorithm for short-term codebook respectively. The former dynamically adjusts feedback period so as to improve the feedback timeliness and uplink feedback resource utilization. The later adopts improved Kalman prediction algorithm to predict CSI. Finally simulation results shows that the proposed schemes can effectively improve the performance of double codebook estimation with outdated CSI.
收起
摘要 :
This paper presents a joint time-frequency-code-power resource management algorithm based on the Nash bargaining solution in time-division long term evolution systems. First, a joint radio resource allocation scheme at the time, f...
展开
This paper presents a joint time-frequency-code-power resource management algorithm based on the Nash bargaining solution in time-division long term evolution systems. First, a joint radio resource allocation scheme at the time, frequency, code and power domain simultaneously is provided for the time-division long term evolution system. Second, the proposed algorithm is modeled as a cooperative game under the constraints of each user's minimal rate requirement and available resources, for example, the maximal transmitting power. To reduce the computational complexity, the joint resource allocation algorithm is divided into time-frequency-code and power domain resource allocation. Also, we could approach the Pareto optimal rate as closely as possible by iterations. Simulation results show that compared with the other resource allocation algorithms, the proposed algorithm has achieved a good tradeoff between the overall system throughput and fairness among different users. Copyright (C) 2012 John Wiley & Sons, Ltd.
收起
摘要 :
In the LTE system, Zadoff-Chu (ZC) sequence is used for the generation and detection of physical random access channel (PRACH) preamble sequence. The key step of PRACH baseband signal generation is to perform a discrete Fourier tr...
展开
In the LTE system, Zadoff-Chu (ZC) sequence is used for the generation and detection of physical random access channel (PRACH) preamble sequence. The key step of PRACH baseband signal generation is to perform a discrete Fourier transform (DFT) of ZC sequence, which is characterized by the root index u and a rotation factor p. On-line computation according to the DFT formula is adopted in traditional algorithm, which has high computational complexity and is hard to meet the real-time requirement of LTE system. In this paper, it is mainly to improve the calculation of rotation factor p in DFT formula. Based on theoretical analysis of the ZC sequence DFT property, the symmetry property and recurrence relations of its rotation factor p are derived. Hence, a small amount of the rotation factors p in a ZC sequence can be calculated off-line and stored in memory firstly. And then all the other rotation factors can be obtained by looking up the table and some simple computations. As a result, the improved ZC sequence DFT can be achieved with less computational effort at a little expense of memory space.
收起
摘要 :
In this work, a tri-band (Band 39: 1880-1920 MHz, Band 40: 2300-2400 MHz, and Band 38: 2570-2620 MHz), 2-receiver (RX) multiple-in-multiple-out (MIMO), 1-transmitter (TX) TD-LTE (Time Division Long Term Evolution) CMOS transceiver...
展开
In this work, a tri-band (Band 39: 1880-1920 MHz, Band 40: 2300-2400 MHz, and Band 38: 2570-2620 MHz), 2-receiver (RX) multiple-in-multiple-out (MIMO), 1-transmitter (TX) TD-LTE (Time Division Long Term Evolution) CMOS transceiver is presented and fabricated in 0.13-μm CMOS technology. The continuous-time delta-sigma A/D converters (CT Δ∑ ADCs) are directly coupled to the RX front-end outputs to achieve low power. With proper gain allocation and a novel carrier leakage calibration, the TX section ensures at least -40 dBc carrier leakage suppression over 86-dB gain range. The transceiver dissipates maximum 171 mW at 2-RX MIMO mode and 183 mW at 1-TX maximum gain mode. To the best of our knowledge, this is the first research paper on fully integrated commercial TD-LTE transceiver.
收起
摘要 :
China has become a significant player in the international standardization regime of telecommunications. It is currently attempting international standardization of its indigenous technologies. This paper examines how China's appr...
展开
China has become a significant player in the international standardization regime of telecommunications. It is currently attempting international standardization of its indigenous technologies. This paper examines how China's approach for standardization has evolved in the cases of locally developed 3G and 4G mobile standards: TD-SCDMA and TD-LTE. The authors address the question in terms of alliance formation. They apply network analysis, which visualizes the formation and transformation of alliances. They argue that China's approach to standardization has evolved from techno-nationalism to techno-globalism. In building, developing, and maintaining alliances, relatively more weight is placed on links with foreign firms over time than on those with local firms, and China is increasingly open to foreign firms to gain their support and cooperation, which is required for international standardization and commercialization of locally-developed standards. This study makes a contribution in that it applies a quantitative method of network analysis and thereby visualizes the formation of alliances in 3G and 4G mobile communication industries.
收起
摘要 :
Contraposing the poor coverage of 4 G, the mobile jitters, large network delay and the characteristics of LTE system resource scheduling in the subway station, this paper proposes an improved resource scheduling algorithm - improv...
展开
Contraposing the poor coverage of 4 G, the mobile jitters, large network delay and the characteristics of LTE system resource scheduling in the subway station, this paper proposes an improved resource scheduling algorithm - improved algorithm of PF utility function based on distance game (hereinafter referred to as M-DG PF/UF algorithm). Then construct optimization model of M-DG PF/UF algorithm, take the distance game on the concurrency user which requests the communication, and take priority scheduling, using the priority as the base parameter, to carry the relevant scheduling out on the subway dynamic resources. Finally, made analysis for the performance of PF, EXP/PF, M-LWDF and M-DG PF/UF algorithm, the simulation results show that the improved algorithm is better than the traditional resource scheduling algorithm, makes the limited system resources of TD-LTE cover more effective users and achieves the optimization goals of subway station radio resource scheduling.
收起
原文获取