The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60617-3
Abstract ( 1264 ) PDF (0 KB)( 145 )
The authors in this article investigated how to cancel multi-user interference with low feedback amount over 3-user multiple input multiple output (MIMO) interference channel using space-time code and precoders. Space-time block code with coding rate 2 was designed, also zero vectors were introduced into each codeword. The multi-user interference is mitigated by pre-coding at the transmitters and nonlinear operation and unidirectional cooperation link at the receivers. Compared with the existing scheme for the same scene, the proposed scheme greatly reduces feedback amount and improves the sum degrees of freedom (DOF). Simulation demonstrates the validity of the proposed scheme.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60618-5
Abstract ( 1896 ) PDF (0 KB)( 142 )
A new variable step-size (VSS) affine projection algorithm (APA) (VSS-APA) was proposed for adaptive feedback cancellation suitable for hearing aids. So, a nonlinear function between step-size and estimation error is established and automatically adjusted according to the change of the estimation error, which leads to low misalignment and fast convergence speed. Analysis of the proposed algorithm offers large capacities in converging to the objective system. Simulation shows that the proposed algorithm achieves lower misalignment and faster convergence speed compared to fixed step-size APA and conventional adaptive algorithms.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60619-7
Abstract ( 1324 ) PDF (0 KB)( 131 )
The authors pay focus on the K user multiple-input multiple-output (MIMO) Gaussian interference channel (IC) with M transmitting antennas and N receiving antennas, in which and . The channel coefficients are variable, time varying or frequency selectively drawn from a continuous distribution. Based on ergodic interference alignment (IA), an achievable scheme was proposed to achieve a total of degrees of freedom (DoF). The ergodic IA scheme can reach the optimal DoF value with simply linear beamforming and finite symbols. Furthermore, the achievable rate of the ergodic IA scheme was derived at any signal-to-noise ratio (SNR). With numerical simulation, the performance of the proposed scheme is evaluated.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60620-3
Abstract ( 1614 ) PDF (0 KB)( 269 )
Virtual network embedding (VNE) is an essential part of network virtualization, which is considered as one of the most promising way for the future network. Its main object is to efficiently assign the nodes and links of a virtual network (VN) to a shared substrate network (SN). The NP-hard and exiting studies have put forward several heuristic algorithms. However, most of the algorithms only consider the local resource of nodes, such as CPU and bandwidth (BW), to decide the embedding, and ignore the significant impact of network attributes. Based on the attributes of entire network, a model of the connectivity between each pair of nodes was formulated to measure the resource ranking of the nodes, and a new two-stage embedding algorithm was proposed. Thereafter, the node mapping and link mapping can be jointly considered. Extensive simulation shows that the proposed algorithm improves the performance of VNE by increasing the revenue/cost ratio and acceptance ratio of VN requests while reducing the runtime.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60621-5
Abstract ( 2615 ) PDF (0 KB)( 129 )
In contention-based satellite communication system, collisions between data packets may occur due to the randomly sending of the packets. A proper delay before each transmission can reduce the data collision rate. As classical random multiple access protocol, the slotted ALOHA (S-ALOHA) reduces the data collision rate through time slot allocation and synchronous measures. In order to improve the stability and throughput of satellite network, a backoff algorithm based on S-ALOHA will be effective. A new adaptive backoff algorithm based on S-ALOHA using grey system was proposed, which calculates the backoff time adaptively according to the network condition. And the network condition is estimated by each user terminal according to the prediction of the channel access success ratio using the model GM (1,1) in grey system. The proposed algorithm is compared to other known schemes such as the binary exponential backoff (BEB) and the multiple increase multiple decrease (MIMD) backoff. The performance of the proposed algorithm is simulated and analyzed. It is shown that throughput of the system based on the proposed algorithm is better than of system based on BEB and MIMD backoff. And there are also some improvements of the delay performance compared to using BEB. The proposed algorithm is especially effective for large number of user terminals in the satellite networks.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60622-7
Abstract ( 1401 ) PDF (0 KB)( 118 )
The fourth generation (4G) wireless communication systems have been deployed or are soon to be deployed in many countries. However, with an explosion of wireless mobile devices and services, there are still some challenges that cannot be accommodated even by the 4G, such as the spectrum crisis and inter-cell interference. Telecom operators have turned to commit themselves to share available resources, including hardware and software resources. Therefore, with the mutual infrastructure, the ‘integration’ should be highlighted, especially in the fifth generation (5G) wireless systems that are expected to be deployed beyond 2020. The authors in the article proposed a potential cellular architecture, and discussed the inter-operator radio interface based synchronization (RIBS) for the 5G wireless communication systems. A scheme of inter-operator RIBS and typical scenarios, along with the analysis of the corresponding interference were given. Analysis of the shared parameters, signaling coordination of inter-operator RIBS and listening reference signal (RS) design for RIBS were also carried out.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60623-9
Abstract ( 1310 ) PDF (0 KB)( 157 )
Quality-of-Service (QoS) describes the non-functional characteristics of Web services. As such, the QoS is a critical parameter in service selection, composition and fault tolerance, and must be accurately determined by some type of QoS prediction method. However, with the dramatic increase in the number of Web services, the prediction failure caused by data sparseness has become a critical challenge. A new ‘hybrid user-location-aware prediction based on weighted Adamic-Adar (WAA)’ (HUWAA) was proposed. The implicit neighbor search was optimized by incorporating location factors. Meanwhile, the ability of the improved algorithms to solve the data sparsity problem was validated in experiments on public real world datasets. The new algorithm outperforms the existing of item-based pearson correlation coefficient (IPCC), user-based pearson correlation coefficient (UPCC) and Web service recommender system (WSRec) algorithms.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60624-0
Abstract ( 1329 ) PDF (0 KB)( 137 )
Traffic light detection and recognition is essential for autonomous driving in urban environments. A camera based algorithm for real-time robust traffic light detection and recognition was proposed, and especially designed for autonomous vehicles. Although the current reliable traffic light recognition algorithms operate well under way, most of them are mainly designed for detection at a fixed position and the effect on autonomous vehicles under real-world conditions is still limited. Some methods achieve high accuracy on autonomous vehicle, but they can’t work normally without the aid of high-precision priori map. The authors presented a camera-based algorithm for the problem. The image processing flow can be divided into three steps, including pre-processing, detection and recognition. Firstly, red-green-blue (RGB) color space is converted to hue-saturation-value (HSV) as main content of pre-processing. In detection step, the transcendental color threshold method is used for initial filterings, meanwhile, the prior knowledge is performed to scan the scene in order to quickly establish candidate regions. For recognition, this article use histogram of oriented gradients (HOG) features and support vector machine (SVM) as well to recognize the state of traffic light. The proposed system on our autonomous vehicle was evaluated. With voting schemes, the proposed can provide a sufficient accuracy for autonomous vehicles in urban enviroment.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60625-2
Abstract ( 1360 ) PDF (0 KB)( 158 )
Biography is a direct and extensive way to know the representation of well known peoples, however, for common people, there is poor knowledge for them to be recognized. In recent years, information extraction (IE) technologies have been used to automatically generate biography for any people with online information. One of the key challenges is the entity linking (EL) which can link biography sentence to corresponding entities. Currently the used general EL systems usually generate errors originated from entity name variation and ambiguity. Compared with general text, biography sentences possess unique yet rarely studied relational knowledge (RK) and temporal knowledge (TK), which could sufficiently distinguish entities. This article proposed a new statistical framework called the knowledge enhanced EL (KeEL) system for automated biography construction. It utilizes commonsense knowledge like PK and TK to enhance Entity Linking. The performance of KeEL on Wikipedia data was evaluated. It is shown that, compared with state-of-the-art method, KeEL significantly improves the precision and recall of Entity Linking.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60626-4
Abstract ( 1321 ) PDF (0 KB)( 128 )
Hyperspectral remote sensing images terrain classification faces the problems of high data dimensionality and lack of labeled training data, resulting in unsatisfied terrain classification efficiency. The feature extraction is required before terrain classification for preserving discriminative information and reducing data dimensionality. A hyperspectral remote sensing images feature extraction method, i.e., discrete cosine transform (DCT) spectral regression discriminant analysis (SRDA) subspace method, was presented to solve the above problems. The proposed DCT SRDA subspace method firstly takes DCT in the original spectral space and gets the DCT coefficients of each pixel spectral curve; secondly performs SRDA in the DCT coefficients space and obtains the DCT SRDA subspace. Minimum distance classifier was designed in the resulting DCT SRDA subspace to evaluate the feature extraction performance. Experiments for two real airborne visible/infrared imaging spectrometer (AVIRIS) hyperspectral images show that, comparing with spectral LDA subspace method, the proposed DCT SRDA subspace method can improve terrain classification efficiency.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60627-6
Abstract ( 1339 ) PDF (0 KB)( 132 )
Parallel acceleration of convolution perfectly matched layer (CPML) algorithm suffers from massive division operation which is widely accepted as one of the most expensive operations for the equipment such as graphic processing unit (GPU), field programmable gate array (FPGA) etc. In pursuit of higher efficiency and lower power consumption, this article revisited the CPML theory and proposed a new fast division-free parallel CPML structure. By optimally rearranging the CPML inner iteration process, all the division operators can be eliminated and replaced by recalculating the related field updating coefficients offline. Experiments show that the proposed division-free structure can save more than 50% arithmetic instructions and 25% execution time of the traditional parallel CPML structure without any accuracy loss.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60628-8
Abstract ( 1310 ) PDF (0 KB)( 127 )
The radiation emission (RE) of multilayer printed circuit board (PCB) will cause electromagnetic compatibility problem. An efficient numerical method for evaluating the effectiveness of decoupling capacitors in reducing RE from power ground (P/G) planes in PCB was presented. A two-dimensional boundary-element method (BEM) was used to establish the radiation model. Then, the RE was calculated by equivalent magnetic current of edge field around P/G planes. Furthermore, the radiation and input impedance of P/G planes mounted decoupling capacitors were calculated for frequency up to 5 GHz. The results were compared to those of the case without decoupling capacitors. It shows that the decoupling capacitors can effectively decrease RE except for anti-resonant frequency. At higher frequencies, the decoupling effectiveness mainly depends on the parasitic inductance of capacitor pin rather than the value.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60629-X
Abstract ( 1342 ) PDF (0 KB)( 132 )
The working state (WS) evaluation is a valuable task in the process of failure diagnosis in the analogue circuits. A fuzzy evaluating algorithm was proposed to quantify the working condition of analogue circuit regarded as fuzzy system. Several familiar WS evaluating functions based on fuzzy membership functions were also proposed to calculate the local working state indexes (WSI) of each node in an analogue circuit. The decision function combined with the WS evaluating functions is used to synthesize all the local WSI to the global WSI of the whole circuit. An example was presented to verify that the working status of the analogue circuits can be described by the new WS evaluating algorithm and the global WSI objectively and accurately.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60630-6
Abstract ( 1386 ) PDF (0 KB)( 121 )
Wavelength division multiplexing (WDM) has been becoming a promising solution to meet the rapidly growing demands on bandwidth. Multicast in WDM networks by employing free wavelength is an efficient approach to saving bandwidth and cost. However, the free wavelength may not identical between different hops in a multicast light-path, particularly in heavy load optical WDM networks. In order to implement multicast applications efficiently, a network coding (NC) technique was introduced into all-optical WDM multicast networks to solve wavelength collision problem between the multicast request and the unicast request. Compared with the wavelength conversion based optical multicast, the network coding based optical multicast can achieve better multicast performance with paying lower cost.
The Journal of China Universities of Posts and Telecommunications, 2015, 22 (1). doi： 10.1016/S1005-8885(15)60631-8
Abstract ( 1512 ) PDF (0 KB)( 274 )
An effective data hiding method based on pixel value differencing (PVD) and modulus function (MF) PVD (MF-PVD) was proposed. MF-PVD method was derived by Wang et al in which the MF was employed to adjust the remainder of two pixels for data embedding and extraction. In the proposed method, a new remainder function in a more general form is defined by selecting proper parameters, in which an indeterminate equation is constructed and an optimal solution is applied to revise the pixels. This strategy leads to a significant image distortion reduction compared with the original method. The experiment reveals that, by preserving the original embedding capacity, the method provides better embedding efficiency than both MF-PVD and PVD methods.