• Title, Summary, Keyword: Wireless Communications

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Blind Source Separation of Instantaneous Mixture of Delayed Sources Using High-Order Taylor Approximation

  • Zhao, Wei;Yuan, Zhigang;Shen, Yuehong;Cao, Yufan;Wei, Yimin;Xu, Pengcheng;Jian, Wei
    • ETRI Journal
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    • v.37 no.4
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    • pp.727-735
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    • 2015
  • This paper deals with the problem of blind source separation (BSS), where observed signals are a mixture of delayed sources. In reference to a previous work, when the delay time is small such that the first-order Taylor approximation holds, delayed observations are transformed into an instantaneous mixture of original sources and their derivatives, for which an extended second-order blind identification (SOBI) approach is used to recover sources. Inspired by the results of this previous work, we propose to generalize its first-order Taylor approximation to suit higher-order approximations in the case of a large delay time based on a similar version of its extended SOBI. Compared to SOBI and its extended version for a first-order Taylor approximation, our method is more efficient in terms of separation quality when the delay time is large. Simulation results verify the performance of our approach under different time delays and signal-to-noise ratio conditions, respectively.

User-Oriented Energy- and Spectral-Efficiency Tradeoff for Wireless Networks

  • Zhang, Yueying;Long, Hang;Peng, Yuexing;Zheng, Kan;Wang, Wenbo
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.7 no.2
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    • pp.216-233
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    • 2013
  • Conventional optimization designs of wireless networks mainly focus on spectral efficiency (SE) as a performance metric. However, as diverse media services are emerging, a green wireless network, which not only meets the quality of experience (QoE) requirements for users and also improves energy efficiency (EE), is the most appropriate solution. In this paper, we firstly propose the unit QoE per Watt, which is termed QoE efficiency (QEE), as a user-oriented metric to evaluate EE for wireless networks. We then analyze which is the kind of wireless resource given priority to use under different scenarios to obtain an acceptable QEE. Particularly, power, delay and data-rate related to QoE are separately addressed for several typical services, such as file download, video stream and web browsing services. Next, the fundamental tradeoffs are investigated between QEE and SE for wireless networks. Our analytical results are helpful for network design and optimization to strike a good balance between the users perceived QoE and energy consumption.

28 GHz Wireless Backhaul Transceiver Characterization and Radio Link Budget

  • Leinonen, Marko E.;Destino, Giuseppe;Kursu, Olli;Sonkki, Marko;Parssinen, Aarno
    • ETRI Journal
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    • v.40 no.1
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    • pp.89-100
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    • 2018
  • Millimeter wave communication is one of the main disruptive technologies in upcoming 5G mobile networks. One of the first candidate applications, which will be commercially ready by 2020, is wireless backhaul links or wireless last mile communication. This paper provides an analysis of this use-case from radio engineering and implementation perspectives. Furthermore, preliminary experimental results are shown for a proof-of-concept wireless backhaul solution developed within the EU-KR 5GCHAMPION project, which will be showcased during the 2018 Winter Olympic Games in Korea. In this paper, we verify system level calculations and a theoretical link budget analysis with conductive and radiated over-the-air measurements. The results indicate that the implemented radio solution is able to achieve the target key performance indicator, namely, a 2.5 Gbps data rate on average, over a range of up to 200 m.

On the Formulation and Optimal Solution of the Rate Control Problem in Wireless Mesh Networks

  • Le, Cong Loi;Hwang, Won-Joo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.5B
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    • pp.295-303
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    • 2007
  • An algorithm is proposed to seek a local optimal solution of the network utility maximization problem in a wireless mesh network, where the architecture being considered is an infrastructure/backbone wireless mesh network. The objective is to achieve proportional fairness amongst the end-to-end flows in wireless mesh networks. In order to establish the communication constraints of the flow rates in the network utility maximization problem, we have presented necessary and sufficient conditions for the achievability of the flow rates. Since wireless mesh networks are generally considered as a type of ad hoc networks, similarly as in wireless multi-hop network, the network utility maximization problem in wireless mesh network is a nonlinear nonconvex programming problem. Besides, the gateway/bridge functionalities in mesh routers enable the integration of wireless mesh networks with various existing wireless networks. Thus, the rate optimization problem in wireless mesh networks is more complex than in wireless multi-hop networks.

Converged Mobile Cellular Networks and Wireless Sensor Networks for Machine-to-Machine Communications

  • Shan, Lianhai;Li, Zhenhong;Hu, Honglin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.6 no.1
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    • pp.147-161
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    • 2012
  • In recent years, machine-to-machine (M2M) communications are under rapid development to meet the fast-increasing requirements of multi-type wireless services and applications. In order to satisfy M2M communications requirements, heterogeneous networks convergence appears in many areas, i.e., mobile cellular networks (MCNs) and wireless sensor networks (WSNs) are evolving from heterogeneous to converged. In this paper, we introduce the system architecture and application requirement for converged MCN and WSN, where mobile terminals in MCN are acting as both sensor nodes and gateways for WSN. And then, we discuss the joint optimization of converged networks for M2M communications. Finally, we discuss the technical challenges in the converged process of MCN and WSN.

Efficient Interference Cancellation Scheme for Wireless Body Area Network

  • Bae, Jung-Nam;Choi, Young-Hoon;Kim, Jin-Young;Kwon, Jang-Woo;Kim, Dong-In
    • Journal of Communications and Networks
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    • v.13 no.2
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    • pp.167-174
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    • 2011
  • In this paper, we propose and simulate an efficient interference cancellation scheme with an optimal ordering successive interference cancellation (SIC) algorithm for ultra wideband (UWB)/multiple-input-multiple-output (MIMO) systems in a wireless body area network (WBAN). When there are several wireless communication devices on a human body, multiple access interference (MAI) usually occurs. To mitigate the effect of MAI and achieve additional diversity gain, we utilize SIC with an optimal ordering algorithm. A zero correlation duration (ZCD) code with robust MAI capability is employed as a spread code for UWB systems in a multi-device WBAN environment. The performance of the proposed scheme is evaluated in terms of the bit error rate (BER). Simulation results confirm that the BER performance can be improved significantly if the proposed interference cancellation scheme and the ZCD code are jointly employed.