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    COMMUNICATION THEORIES & SYSTEMS
  • COMMUNICATION THEORIES & SYSTEMS
    Hao Zhang, Hongyan Li, Jung Hoon Lee
    2017, 14(4): 1-10.
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    In this paper, we exploit clustered interference alignment (IA) for efficient subchannel allocation in ultra-dense orthogonal frequency division multiplexing access (OFDMA) based femtocell networks, which notably improves the spectral efficiency as well as addresses the feasibility issue of IA. Our problem is formulated as a combinatorial optimization problem which is NP-hard. To avoid obtaining its optimal solution by exhaustive search, we propose a two-phases efficient solution with low-complexity. The first phase groups all the femtocell user equipments (FUEs) into disjoint clusters, and the second phase allocates subchannels to the formed clusters where IA is performed. By doing this, the intra-cluster and inter-cluster interferences are mitigated by clustered IA and subchannel allocation in ultra-dense femtocell networks, respectively. Also, low-complexity algorithm is proposed to solve the corresponding sub-problem in each phase. Simulation results demonstrate that the proposed scheme not only outperforms other related schemes, but also provides a close performance to the optimal solution.
  • COMMUNICATION THEORIES & SYSTEMS
    Muhammad Saad Khan, Hongxin Zhang, Fan Zhang, Sulman Shahzad, Rahat Ullah, Sajid Ali, Qasim Ali Arain, Manzoor Ahmed
    2017, 14(4): 11-19.
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    Advanced wireless standards of communication like 3GPP and LTE are becoming more and more efficient and with this evolution of communication systems mobile equipment is also become smaller and smaller. Power amplifier designing has become a very crucial task in this era where efficiency and size are the main concern of any designer. In this paper we have design and analyzed X-band Class E Metal-semiconductor field effect transistor (MESFET) based Power Amplifier. This device targets the devices which use OFDM technique to improve their spectral efficiency for the next generation communication systems. Microstrip lines are used to achieve small size for our design instead of lumped components. Load Pull measurements are used to get MESFET input and output impedances optimum values. For linear and non linear operation small signal mathematical model of the design is used. To reduce thermal losses FR4 substrate is used to increase PA efficiency. Our designs shows small values of input and output return loss of about -22.3dB and -23.716 dB achieving a high gain of about 25.6 dB respectively, with PAE of about 30 % having stability factor greater than 1 and 21.894dBm of output power.
  • COMMUNICATION THEORIES & SYSTEMS
    Ji Zhang, Dafang Zhang, Kun Xie, Hong Qiao, Shiming He
    2017, 14(4): 20-34.
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    Energy efficiency is an important criterion for routing algorithms in the wireless sensor network. Cooperative routing can reduce energy consumption effectively stemming from its diversity gain advantage. To solve the energy consumption problem and maximize the network lifetime, this paper proposes a Virtual Multiple Input Multiple Output based Cooperative Routing algorithm (VMIMOCR). VMIMOCR chooses cooperative relay nodes based on Virtual Multiple Input Multiple Output Model, and balances energy consumption by reasonable power allocation among transmitters, and decides the forwarding path finally. The experimental results show that VMIMOCR can improve network lifetime from 37% to 348% in the medium node density, compared with existing routing algorithms.
  • COMMUNICATION THEORIES & SYSTEMS
    V.Akila, T.Sheela, G.Adiline Macriga
    2017, 14(4): 35-46.
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    Wireless Sensor Networks (WSNs) has become a popular research topic due to its resource constraints. Energy consumption and transmission delay is crucial requirement to be handled to enhance the popularity of WSNs. In order to overcome these issues, we have proposed an Efficient Packet Scheduling Technique for Data Merging in WSNs. Packet scheduling is done by using three levels of priority queue and to reduce the transmission delay. Real-time data packets are placed in high priority queue and Non real-time data packets based on local or remote data are placed on other queues. In this paper, we have used Time Division Multiple Access (TDMA) scheme to efficiently determine the priority of the packet at each level and transmit the data packets from lower level to higher level through intermediate nodes. To reduce the number of transmission, efficient data merge technique is used to merge the data packet in intermediate nodes which has same destination node. Data merge utilize the maximum packet size by appending the merged packets with received packets till the maximum packet size or maximum waiting time is reached. Real- time data packets are directly forwarded to the next node without applying data merge. The performance is evaluated under various metrics like packet delivery ratio, packet drop, energy consumption and delay based on changing the number of nodes and transmission rate. Our results show significant reduction in various performance metrics.
  • COMMUNICATION THEORIES & SYSTEMS
    Wei Wang, Dake Liu, Ying Zhang, Chen Gong
    2017, 14(4): 47-64.
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    There are already several power models to estimate the power consumption of base stations at system level. However, there is so far no model that can predict power consumption of the future base station designs based on algorithms and hardware selections with insufficient physical information. We present such an energy model for typical base stations. This model can help designers in estimating, evaluating and optimizing energy/power consumption of candidate designs in early design stages. The proposed model is verified by an LTE extreme scenario. The estimated results show that digital front-end, channel equalization and channel decoding are three major power greedy modules (consuming 39.4%, 16.3%, 13.4%) in a digital baseband subsystem. The power estimation error of the proposed power amplifier (PA) power model is 3.5% (macro cell). The major contribution of this paper is that the proposed models can rapidly estimate energy/power consumption of 4G and the future base stations (such as 5G) in early design stages with well acceptable precision, even without sufficient implementation information.
  • COMMUNICATION THEORIES & SYSTEMS
    Shuangshuang Han, Xiang Cheng, Liuqing Yang
    2017, 14(4): 65-72.
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    An estimate-and-forward (EF) scheme for single-input single-output (SISO) and multiple-input multiple-output (MIMO) full-duplex two-way relay networks is proposed and analyzed. The relay estimates the received signal from two terminal nodes by a minimum mean squared error (MMSE) estimation and forwards a scaled version of the MMSE estimate to the destination. The proposed EF outperforms conventional amplify-and-forward (AF) and decode-and-forward (DF) across all signal-to-noise ratio (SNR) region. Because its computational complexity is high for relays with a large number of antennas (large MIMO) and/or high order constellations, an approximate EF scheme, called list EF, are thus proposed to reduce the computational complexity. The proposed list EF computes a candidate list for the MMSE estimate by using a sphere decoder, and it approaches the performance of the exact EF relay at a negligible performance loss. The proposed forwarding approach also could be used to other relay networks, such as half-duplex, one-way or massive MIMO relay networks.
  • NETWORKS & SECURITY
  • NETWORKS & SECURITY
    Hongwei Meng, Zhong Chen, Jianbin Hu, Chuck Song, Cong Tang
    2017, 14(4): 73-88.
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    Integrating mobility and security in the network layer has become a key factor for Future Internet Architecture (FIA). This paper proposes a secure mobility support mechanism in eXpressive Internet Architecture (XIA), a new FIA currently under development as part of the US National Science Foundation's (NSF) program. Utilizing the natural features of ID/locator decoupling and versatile routing in XIA, a general mechanism to support host mobility is proposed. Exploiting the self-certifying identifier, a secure binding update protocol to overcome the potential threats introduced by the proposed mobility support mechanism is also given. We demonstrate that our design in XIA outperforms IP based solutions in terms of efficiency and flexibility. We also outline our initial design to illustrate one derivative benefit of an evolvable architecture: mobility support customizability with no sacrifice of architectural generality.
  • NETWORKS & SECURITY
    Qasim Ali Arain, Zhongliang Deng, Imran memon, Asma Zubedi, Jichao Jiao, Aisha Ashraf, Muhammad Saad Khan
    2017, 14(4): 89-100.
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    In this research we proposed a strategy for location privacy protection which addresses the issues related with existing location privacy protection techniques. Mix-Zones and pseudonyms are considered as the basic building blocks for location privacy; however, continuously changing pseudonyms process at multiple locations can enhance user privacy. It has been revealed that changing pseudonym at improper time and location may threat to user's privacy. Moreover, certain methods related to pseudonym change have been proposed to attain desirable location privacy and most of these solutions are based upon velocity, GPS position and direction of angle. We analyzed existing methods related to location privacy with mix zones, such as RPCLP, EPCS and MODP, where it has been observed that these methods are not adequate to attain desired level of location privacy and suffered from large number of pseudonym changes. By analyzing limitations of existing methods, we proposed Dynamic Pseudonym based multiple mix zone (DPMM) technique, which ensures highest level of accuracy and privacy. We simulate our data by using SUMO application and analysis results has revealed that DPMM outperformed existing pseudonym change techniques and achieved better results in terms of acquiring high privacy with small number of pseudonym change.
  • NETWORKS & SECURITY
    Muhammad Azam Zia, Zhongbao Zhang, Ximing Li, Haseeb Ahmad, Sen Su
    2017, 14(4): 101-110.
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    Recently, the community analysis has seen enormous research advancements in the field of social networks. A large amount of the current studies put forward different models and algorithms about most influential people. However, there is little work to shed light on how to rank communities while considering their levels that are determined by the quality of their published contents. In this paper, we propose solution for measuring the influence of communities and ranking them by considering joint weight composed of internal and external influence of communities. To address this issue, we design a novel algorithm called ComRank: a modification of PageRank, which considers the joint weight in order to identify impact of each community and ranking them. We use real-world data trace in citation network and perform extensive experiments to evaluate our proposed algorithm. The comparative results depict significant improvements by our algorithm in community ranking due to the inclusion of proposed weighting feature.
  • SIGNAL PROCESSING FOR COMMUNICATIONS
  • SIGNAL PROCESSING FOR COMMUNICATIONS
    Hengzhou Xu, Dan Feng, Cheng Sun, Baoming Bai
    2017, 14(4): 111-119.
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    In this paper, we study the rank of matrices over GF(2p) and propose two construction methods for algebraic-based nonbinary LDPC codes from an existing LDPC code, referred to as the original code. By multiplying all elements of each column of the binary parity-check matrix H corresponding to the original code with the same nonzero element of any field, the first class of nonbinary LDPC codes with flexible field order is proposed. The second method is to replace the nonzero elements of some columns in H with different nonzero field elements in a given field, and then another class of nonbinary LDPC codes with various rates is obtained. Simulation results show that the proposed nonbinary LDPC codes perform well over the AWGN channel with the iterative decoding algorithms.
  • SIGNAL PROCESSING FOR COMMUNICATIONS
    Bin Duo, Xiaoling Zhong, Yong Guo
    2017, 14(4): 127-139.
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    In this paper, based on the characteristics of polar codes, a new decode-and-forward strategy called generalized partial information relaying protocol is proposed for degraded multiple-relay networks with orthogonal receiver components (MRN-ORCs). In such a protocol, with the help of partial information from previous nodes, each relay node tries to recover the received source message and re-encodes part of the decoded message for transmission to satisfy the decoding requirements for the following relay node or the destination node. In order to construct practical polar codes, the nested structures are developed based on this protocol and the information sets corresponding to the partial messages forwarded are also calculated. The proposed scheme is proved to be capable of achieving the theoretical capacity of the degraded MRN-ORCs while still retains the low-complexity feature of polar codes. We perform simulations to testify the practicability of the proposed scheme and compare polar codes by using successive-cancellation list decoder (SCLD) with traditional low-density parity-check (LDPC) codes. The results show that the obtained polar codes provide significant gain.
  • SIGNAL PROCESSING FOR COMMUNICATIONS
    Chengjie Li, Lidong Zhu, Zhongqiang Luo
    2017, 14(4): 140-149.
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    The problem of underdetermined blind source separation of adjacent satellite interference is proposed in this paper. Density Clustering algorithm (DC-algorithm) presented in this article is different from traditional methods. Sparseness representation has been applied in underdetermined blind signal source separation. However, some difficulties have not been considered, such as the number of sources is unknown or the mixed matrix is ill-conditioned. In order to find out the number of the mixed signals, Short Time Fourier Transform (STFT) is employed to segment received mixtures. Then, we formulate the blind source signal as cluster problem. Furthermore, we construct Cost Function Pair (p,δ) and Decision Coordinate System by using density clustering. At the end of this paper, we discuss the performance of the proposed method and verify the novel method based on several simulations. We verify the proposed method on numerical experiments with real signal transmission, which demonstrates the validity of the proposed method.