PENG Fei, WANG Ying, ZHANG Wei-dong, YUAN Yuan
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60261-2
Abstract ( 1338 ) PDF (0 KB)( 166 )
Two-dimensional (2D) multiple-input multiple-output (MIMO) is currently concentrated on propagation in horizontal plane, but the impact of elevation angle is not considered. However, due to the three-dimensional (3D) character of the real MIMO channel, 2D MIMO cannot achieve the optimal system throughput. A multiple-user MIMO (MU-MIMO) user pairing scheme was proposed, in which the vertical dimension was taken into consideration. In the proposed scheme, a 3D codebook based on full dimension MIMO channel was designed; then two 3D MU-MIMO user’s pairing schemes are proposed combining the proposed joint and separate 3D codebook. Simulation evaluates the proposed 3D codebook aided user pairing scheme and compares with the previous 2D MU-MIMO user pairing technology. Owing to the additional spatial degree of freedom in vertical dimension, the proposed 3D MU-MIMO user pairing schemes can effectively improve the overall system performance.
ZHANG Ying-hui, ZHANG Tian-kui, SAEED-Muhammad, ZENG Zhi-min
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60262-4
Abstract ( 1119 ) PDF (0 KB)( 127 )
The transmission antennas of cooperative systems are spatially distributed on multiple nodes, so the received signal can be asynchronous due to propagation delays. A receiving scheme for cooperative relay networks is proposed, multiple asynchronous signals are reconstructed at the receiver by forward and backward interference cancellation, which can obtain gains of cooperative transmission diversity with obvious delay and with no requiring timing synchronization or orthogonal channelization between relays. Analysis and simulation show that the bit error rate (BER) of the proposed scheme is similar to Alamouti code, and the scheme has the diversity order of orthogonal transmission scheme accompanied by minimal BER losses. It is demonstrated that the performance can be further improved by adding an error correcting code (ECC).
YAN Sheng-nan, LI Yan
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60263-6
Abstract ( 1109 ) PDF (0 KB)( 169 )
This paper investigates the performance of an underlay cognitive relay system where secondary users (SUs) suffer from a primary outage probability constraint and spectrum-sharing interference imposed by a primary user (PU). In particular, we consider a secondary multi-relay network operating in the selection decode-and-forward (SDF) mode and propose a best-relay selection criterion which takes into account the spectrum-sharing constraint and interference. Based on these assumptions, the closed-form expression of the outage probability of secondary transmissions is derived. We find that a floor of the outage probability occurs in high signal-to-noise ratio (SNR) regions due to the joint effect of the constraint and the interference from the PU. In addition, we propose a generalized definition of the diversity gain for such systems and show that a full diversity order is achieved. Simulation results verify our theoretical solutions.
YU Yin-hui, SUN Chen, QIN Nan-nan, GAO Ke, CHEN Deng-zhao
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60264-8
Abstract ( 1180 ) PDF (0 KB)( 147 )
This article introduces the classic locating method based on the receiving signal strength in the cognitive radio and puts forward a cognitive radio-receiving signal strength (CR-RSS) localization algorithm which solves the problem of secondary users locating the primary user and succeeds in estimating the primary user’s location and transmission power. Through the establishment of cognitive radio network, evaluating the number of secondary users ,sampling and the environmental factors to the results in CR-RSS approach. The consequence shows that this approach can effectively locate the primary user and the technology of localization in cognitive radio can assist network optimization.
GUO Wei-jie, HUANG Liu-sheng, SUN Quan, XU Hong-li, ZHANG Hao-ra
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60265-X
Abstract ( 1500 ) PDF (0 KB)( 133 )
In vehicular Ad-hoc network (VANET), many multi-hop broadcast schemes are employed to widely propagate the warning messages among vehicles and the key is to dynamically determine the optimal relay vehicle for retransmission. In order to achieve reliable and fast delivery of warning messages, this paper proposes a delay-aware and reliable broadcast protocol (DR-BP) based on transmit power control technique. First, a comprehensive model is derived to evaluate the transmission in vehicle-to-vehicle communications. This model considers the wireless channel fading, transmission delay and retransmissions characters occurring in the physical layer/medium access control (PHY/MAC) layer. Then, a local optimal relay selection mechanism based on the above model is designed. In DR-BP scheme, only the vehicle selected as the optimal relays can forward warning messages and the transmit power is time-varying. Finally, extensive simulations verify the performance of DR-BP under different traffic scenarios. Simulation results show that DR-BP outperforms the traditional slotted 1-persistence (S1P) and flooding scheme in terms of packets delivery ratio and transmission delay.
LI Li, WU Wei, CHEN Jian-ya, LIU Yun-jie
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60266-1
Abstract ( 1213 ) PDF (0 KB)( 126 )
Because of its potential applications in agriculture, environment monitoring and so on, wireless underground sensor network (WUSN) has been researched more and more extensively in recent years. The main and most important difference of WUSN to terrestrial wireless sensor network (WSN) is the channel characteristics, which determines the design methodology of it. In this paper, the propagation character of electromagnetic (EM) wave in the near surface WUSN is analyzed, as well as the path loss model of it is given. In addition, the influence of human’s ankle to the channel characteristics of near surface WUSN is investigated by electromagnetic theory analysis, simulation and experiment. A novel path loss model of near surface WUSN which takes the interference of human’s ankle into consideration is proposed. It is verified that the existing of human above the WUSN system may cause additional attenuation to the signal of near surface WUSN which propagates as lateral wave along the ground. Moreover, the relation of the attenuation and operating frequency is deduced, which gives a reference to extend the frequency band applied in WUSN.
WANG Ya-li, SONG Mei, WEI Yi-fei, WANG Ying-he, WANG Xiao-jun
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60267-3
Abstract ( 1175 ) PDF (0 KB)( 132 )
In order to establish a route supporting multi-constrained quality of service (QoS), increase network throughput and reduce network energy consumption, an improved ant colony-based multi-constrained QoS energy-saving routing algorithm (IAMQER) is proposed. The ant colony algorithm, as one of the available heuristic algorithms, is used to find the optimal route from source node to destination node. The proposed IAMQER algorithm, which is based on the analysis of local node information such as node queue length, node forwarding number of data packets and node residual energy, balances the relationship between the network throughput and the energy consumption, thus improving the performance of network in multi-constrained QoS routing. Simulation results show that this IAMQER algorithm can find the QoS route that reduce average energy consumption and improves network packet delivery ratio under the end-to-end delay and packet loss ratio constraints.
DU Xiu-juan, HUANG Ke-jun, LAN Sheng-lin, FENG Zhen-xing, LIU Fan
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60268-5
Abstract ( 1177 ) PDF (0 KB)( 133 )
Underwater sensor network (UWSN) adopts acoustic communication with more energy-consumption and longer propagation-delay, which bring great challenges to protocol design. In this paper, we proposed level-based adaptive geo-routing (LB-AGR) protocol. LB-AGR divides traffics into four categories, and routes different types of traffic in accordance with different decisions. Packets upstream to the sink are forwarded unicast to the best next-hop instead of broadcasting to all neighbor nodes as in present UWSN routing protocols. LB-AGR defines an integrated forwarding factor for each candidate node based on available energy, density, location, and level-difference between neighbor nodes, which is used to determine the best next-hop among multiple qualified candidates. Through simulation experiments, we show the promising performance of LB-AGR.
YU Yu, GUO Zhong-wen
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60269-7
Abstract ( 1425 ) PDF (0 KB)( 142 )
A compression algorithm is proposed in this paper for reducing the size of sensor data. By using a dictionary-based lossless compression algorithm, sensor data can be compressed efficiently and interpreted without decompressing. The correlation between redundancy of sensor data and compression ratio is explored. Further, a parallel compression algorithm based on MapReduce  is proposed. Meanwhile, data partitioner which plays an important role in performance of MapReduce application is discussed along with performance evaluation criteria proposed in this paper. Experiments demonstrate that random sampler is suitable for highly redundant sensor data and the proposed compression algorithms can compress those highly redundant sensor data efficiently.
CHENG Gang , SONG Mei, ZHANG Yong, XING Yi-hai, BAO Xu-yan
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60270-3
Abstract ( 1123 ) PDF (0 KB)( 133 )
Opportunistic networks are derived from delay tolerant networks, where mobile nodes have no end-to-end connections. Nodes are represented by people, which means that opportunistic networks can be regarded as social networks. Human mobility plays an important role in affecting the performance of forwarding protocols in social networks, furthermore, the trajectory of people’s movements are driven by social characteristics. However, current routing protocols rely on simple mobility models, and rarely consider social characteristics. Considering two heterogeneous network models, an social opportunistic networks routing (SONR) was proposed which brings an adapted discrete Markov chain into nodes’ mobility model and calculates the transition probability between successive status. Comparison was made between Spray, Wait and Epidemic protocol. Simulation show that SONR can improve performance on delivery ratio, delivery latency and network overhead, meanwhile. SONR approaches the performance of Epidemic routing.
WU Xu-guang , LI Yi, JI Hong
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60271-5
Abstract ( 1232 ) PDF (0 KB)( 183 )
In downlink coordinated multi-point (CoMP) system, full cooperation is always not applicable in real world because of its high request in the backhaul. To deal with this problem, clustering decision is made to process transmission. In this paper clustering methods based on the metric signal-to-leakage-plus-noise (SLNR) is proposed. In addition, user scheduling schemes based on SLNR is also put up to make the scheduling set as large as possible. Simulation results show that the proposed clustering methods not only reduce the data sharing among the cooperating base stations (BSs), but also improve the system throughput compared with the traditional clustering methods based on channel strength.
LIU Jing , XU Guo-sheng, ZHENG Shi-hui, XIAO Da, GU Li-ze
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60272-7
Abstract ( 1210 ) PDF (0 KB)( 120 )
The main challenges of data streams classification include infinite length, concept-drifting, arrival of novel classes and lack of labeled instances. Most existing techniques address only some of them and ignore others. So an ensemble classification model based on decision-feedback (ECM-BDF) is presented in this paper to address all these challenges. Firstly, a data stream is divided into sequential chunks and a classification model is trained from each labeled data chunk. To address the infinite length and concept-drifting problem, a fixed number of such models constitute an ensemble model E and subsequent labeled chunks are used to update E. To deal with the appearance of novel classes and limited labeled instances problem, the model incorporates a novel class detection mechanism to detect the arrival of a novel class without training E with labeled instances of that class. Meanwhile, unsupervised models are trained from unlabeled instances to provide useful constraints for E. An extended ensemble model Ex can be acquired with the constraints as feedback information, and then unlabeled instances can be classified more accurately by satisfying the maximum consensus of Ex. Experimental results demonstrate that the proposed ECM-BDF outperforms traditional techniques in classifying data streams with limited labeled data.
HUANG Qin-long , FU Jing-yi, MA Zhao-feng, YANG Yi-xian, NIU Xin-xin
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60273-9
Abstract ( 1223 ) PDF (0 KB)( 149 )
The online social networks (OSNs) offer attractive means for social interactions and data sharing, as well as raise a number of security and privacy issues. Although current solutions propose to encrypt data before sharing, the access control of encrypted data has become a challenging task. Moreover, multiple owners may enforce different access policy to the same data because of their different privacy concerns. A digital rights management (DRM) scheme is proposed for encrypted data in OSNs. In order to protect users’ sensitive data, the scheme allows users outsource encrypted data to the OSNs service provider for sharing and customize the access policy of their data based on ciphertext-policy attribute-based encryption. Furthermore, the scheme presents a multiparty access control model based on identity-based broadcast encryption and ciphertext-policy attribute-based proxy re-encryption, which enables multiple owners, such as tagged users who appear in a single data, customize the access policy collaboratively, and also allows the disseminators update the access policy if their attributes satisfy the existing access policy. Security analysis and comparison indicate that the proposed scheme is secure and efficient.
GUO Cong, ZHANG Zi-jian, ZHU Lie-huang, TAN Yu-an, YANG Zhen
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60274-0
Abstract ( 1339 ) PDF (0 KB)( 197 )
The trend of researching group radio frequency identification devices (RFID) authentication protocol has become increasingly popular in recent years. One of the newest work in this area is from Batina and Lee, they presented a privacy-preserving multi-players grouping-proof protocol based on the elliptic curve cryptography (ECC), and claimed their protocol have the ability to resist five potential attacks, including compromised tag attack, man-in-the-middle attack, colluding tags attack, etc. In this paper, we first take a counterexample to demonstrate their protocol is vulnerable to compromised tag attack. Then we propose a novel secure RFID authentication protocol, and analyze its security by merging formal analysis, provable security, and mathematical inductive method, so as to solve the weakness of Batina and Lee’s work. Furthermore, compared with another two classic protocols (secure ownership transfer protocol (SOTP) and secure multiple group ownership transfer protocol (SMGOTP)), the performance analysis show that our protocol provides not only a lower tags’ communication cost at about 50.0% and 14.3%, but also a lower reader’s computation cost (approximate 14.5% and 55.1% respectively), when transferring a large number of tags.
LIU Xuan, ZHANG Wen-ying, LIU Xiang-zhong, LIU Feng
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60275-2
Abstract ( 1163 ) PDF (0 KB)( 137 )
In this paper, we present a new lightweight block cipher named eight-sided fortress (ESF), which is suitable for resource-constrained environments such as sensor networks and low-cost radio rrequency identification (RFID) tags. Meanwhile, we present the specification, design rationale and evaluation results in terms of the hardware implementation. For realizing both efficiency and security in embedded systems, similar to the other lightweight block ciphers, ESF is 64 bits block length and key size is 80 bits. It is inspired from existing block cipher, PRESENT and LBlock. The encryption algorithm of ESF is based on variant Feistel structure with SPN round function, used Feistel network as an overall structure with the purpose of minimizing computational resources.
ZHANG Deng-yin, WU Yuan-yuan, WAN Ming-xiang
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60276-4
Abstract ( 1209 ) PDF (0 KB)( 135 )
Side information has a significant influence on the rate-distortion (RD) performance of distributed video coding (DVC). In the conventional motion compensated frame interpolation scheme, all blocks adopt the same side-information generation method regardless of the motion intensity inequality at different regions. In this paper, an improved method is proposed. The image blocks are classified into two modes, fast motion and slow motion, by simply computing the discrete cosine transformation (DCT) coefficients at the encoder. On the decoder, it chooses the direct interpolation and refined motion compensated interpolation correspondingly to generate side information. Experimental results show that the proposed method, without increasing the encoder complexity, can increase the average peak signal-to-noise ratio (PSNR) by up to 1~ 2 dB compared with the existing algorithm. Meanwhile, the proposed algorithm significantly improves the subjective quality of the side information．
SUN Yue-ping, WANG Xiao-jie, WANG Xu-wen, JIANG Shao-wei, LIU Yong-bin
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60277-6
Abstract ( 1092 ) PDF (0 KB)( 116 )
Community-based question answer (CQA) makes a figure network in development of social network. Similar question retrieval is one of the most important tasks in CQA. Most of the previous works on similar question retrieval were given with the underlying assumption that answers are similar if their questions are similar, but no work was done by modeling similarity measure with the constraint of the assumption. A new method of modeling similarity measure is proposed by constraining the measure with the assumption, and employing ensemble learning to get a comprehensive measure which integrates different context features for similarity measuring, including lexical, syntactic, semantic and latent semantic. Experiments indicate that the integrated model could get a relatively high performance consistence between question set and answer set. Models with better consistency tend to get a better precision according to answers.
ZHUANG Yu-feng, LIU Dong-qiang, WANG Jun-guang
The Journal of China Universities of Posts and Telecommunications, 2014, 21 (1). doi： 10.1016/S1005-8885(14)60278-8
Abstract ( 1184 ) PDF (0 KB)( 167 )
In this paper, a walking robot is established. The zero-moment point (ZMP) is used to stabilize the working robot. The kinematic model of the robot based on denavit-hartenberg (D-H) method is presented in this thesis. And then the dynamic model, based on Lagrange method, is built by simplifying the kinematic model of robot body. A kinematic simulation to the robotic system is achieved based on Adams. Driving torque of left ankle is calculated according to joint angle, angular velocity and angular acceleration. The validity of the dynamic model is testified by comparing with the result of simulation.