- EI核心期刊
A summarization of published research achievements about interconnection between wireless sensor networks and transmission control protocol/ Internet protocol（TCP/IP ）networks is presented. Two different ways to connect wireless sensor networks with TCP/IP networks: proxy architectures and direct TCP/IP architectures for sensor networks are discussed. Investigation shows that the proxy architectures will provide simple access and high security level, while direct TCP/IP architectures have better extensibilities and robustness. Also, based on full analysis, a hybrid approach combined proxy architectures is proposed together with direct TCP/IP architectures to have their respective advantages.
Based on the requirements of information security for spacecraft telecommand and data protection mechanism adopted, the weakness of short length spacecraft telecommand messages in secure transmission was analyzed. To overcome the weakness a message extension method based on physical chaos source and its application were presented in this paper. The channel error control measures applied with the message extension method were also presented. With the method mentioned the entropy of telecommand messages will obviously be increased and the security of transmission enhanced as well.
The management information modeling methods of connectionless network are studied based on the characteristic concept of connectionless network - flow. The contents involve the basic principles of information modeling of connectionless network, the transform mechanisms from functional architecture components to managed resources, and the principles to identify the relationships between managed resources，as well as essential attributes of those resources. The modeling methods proposed here focuses on the guidance for detailed steps during the modeling process. The characteristics of connectionless networks as well as the concept of flow are analyzed, and the management abstraction from functional architecture components to managed resources is dwelt on. The methods have been applied in the information modeling of Ethernet passive optical networks (EPON) network management interface, and the information model has already been accepted as ITU-T recommendation Q.838.1.
Four vector equations are established for the non-planar nine-link Barranov truss. A vector method with complex numbers according to four loops and its equations are changed onto an equitation group with complex exponential form. Above all, the 4 equations are reduced to a 46 degree univariate polynomial equation by Sylvester resultant elimination and the other 3 variables are solved by Euclid’s Algorithm. A numerical example is given, it verifies that assembly configurations number of the Barranov truss is 46.
Tô et al. presented a bilinear-map-based traitor tracing scheme with revocation, but it is a symmetric scheme because it does not provide non-repudiation. An improved Tô scheme was proposed using oblivious polynomial evaluation (OPE) protocol and service parameters. Under the precondition of general sameness capabilities of both Tô’s and improved Tô’s scheme, the new scheme adds some advantages such as providing multi-service capability, user’s non-repudiation and data provider’s no-framing innocent users. Furthermore, it is also proved to be semantically secure under the decisional bilinear Diffie-Hellman problem (DBDH) assumption.
Personalized information service is studied for providing high quality mobile information service to mobile users. Based on the mobile off-line reading system, an algorithm of the individuation recommendation service is proposed. The K near neighbors classification method is adjusted so as to trace, log, model and analyze the series of users’ actions for news browsing. Then the personalized features are classified and saved, and could be used later in the system to provide the real-time individual information recommendation for each user’s access to news. Simulation experiment result has certified the utility and feasibility of the individual recommendation algorithm. The accuracy of the recommendation can reach 70%.
The construction and enumeration of symmetric balanced Boolean functions is equivalent to the solution and enumeration of the solution of one knapsack equation with n variables in the binary field. There exist two trivial solutions of this knapsack equation when is even. The necessary and sufficient condition under which there exist non-trivial solutions of this knapsack equation was given when is even. A method for finding out the non-trivial solutions was also shown. Some non-trivial solutions of this knapsack equation were found out when and.
A new method of the performance measurement definition is presented based on unified telecommunication management network （TMN） requirements, analysis and design (UTRAD) methodology . The method including four steps describes the action and process of each step, introduces the measurement definition communities and their roles in each step, and meets the performance measurement requirements of every management layer. It also indicates how the performance measurement requirements can be transformed into the performance measurements. Compared with the existing methods, meanwhile, the method inherits some useful properties from the existing methods, abandons some improper properties and presents some new properties.
Based on uniform linear array, a blind estimating algorithm for spatial signature of uplink signals was presented. Using the fourth order cumulant of array output, a spatial-signature-matrix was constructed with the algorithm. It was proved that the spatial signature of each user can be obtained via decomposition of the spatial-signature-matrix. The algorithm is not dependent upon the modulation type of signal, and can be employed to additive arbitrary Gaussian noise. Applying it to estimate spatial signature of multi-user with coherent multi-path, the standard estimation deviations at different snapshots and signal-to-noise-ratio (SNR) were studied. The results confirm the availability and robustness of the algorithm.
A novel multiuser transmission (MUT) model is developed. In this model, the smart antennas method is combined the multiuser transmission. The smart antennas are used to eliminate the space interference and the MUT is used to mitigate the multiple-access interference (MAI) and the inter-symbol interference (ISI). The simulation in the time division–synchronous code division multiple access（TD-SCDMA） system shows that the proposed system model can achieve a better performance than the model which only uses MUT method in the spatial domain environment.
A segmentation method by multiscale weight aggregation is presented for segmentation of the tree crowns based on the digital surface model (DSM). The tree top from the DSM for the segmentation of the tree crown is firstly selected. Then the tree top is projected to the aerial image as the seed of the segmentation. Based on a global measure, an algebraic multigrid technique is used to construct the pixels to a multiscale segmented image by weight aggregation. Through the position of the seed and the image size, the segmented tree crown is obtained. The experimental results demonstrate that the algorithm can accurately segment the tree crown which is projected to different viewing angle aerial images
Differed from the traditional resolution of selecting a service with highest priority, a method was proposed to resolve the shared trigger interaction(STI) .It includes two steps. Firstly, the shared trigger services are divided into consistent service set and conflict service set. Secondly, combining the user intention with the system policy, the services in the consistent service set are conducted in turn, and one of the services with the highest priority in the conflict service set is executed in the end. The research of the service instances shows that the method is simple and efficient, and can execute the service as much as possible.
The implementation and practicability of dynamic parallel paths traffic engineering (DPPTE) with genetic algorithm was analyzed. An algorithm for the theoretical optimization of DPPTE was offered at first. The computing cost and the outcome were unrealized technically. Thereafter, a new genetic algorithm was designed based on practicable traffic assignment solutions, and the optimization performance of the algorithm was closed to the theoretical one with a little computing cost. The simulations proves that traffic assignment errors between parallel paths will be controlled in the optimizing.
A cross-layer radio resource allocation scheme is proposed with guaranteed divers quality of service ( QoS) for multi-user orthogonal frequency division multiplex （OFDM） system. In order to maximize the system throughput under satisfying the QoS requirement of real-time and non-real-time services, packet scheduling, subchannel allocation and adaptive modulation and coding （AMC）schemes are jointly designed. The channel dependent earliest due date (CD-EDD) and minimum rate request(MRR) disciplines are employed for the resource allocation for real-time and non-real-time services respectively. The performance of the proposed algorithm is evaluated on the IEEE 802.16 standard-based dynamical system-level simulation. The results reveal that the proposed algorithm can perform better than maximum signal noise ratio strategy in terms of average packet delay and user fairness with the near throughput.
The method of multilevel parallel phase modulation (MPPM) was proposed, which means two parallel multilevel phase shift keying（MPSK） signals were transmitted with one frequency at the same symbol period. The MPPM system model was presented and the mechanisms of modulation and demodulation of MPPM were theoretically analyzed. Furthermore, the methods of improving the bit error performance of MPPM were studied. The simulation results show that 16PPM performs better than 16-ary phase shift keying（16PSK） by 2dB at bit error rate of 10-3 over additive white Gaussian noise (AWGN) channels. By optimizing the parameters of phases at transmitter, 16PPM is superior to 16-ary quadrature amplitude modulation（16QAM） over Rayleigh flat-fading channels. MPPM can greatly improve the transmitting data rate and bandwidth efficiency, which can be utilized for the future mobile communication.
An information-driven sensor selection algorithm is proposed to select sensors to participate in Kalman filtering for target state estimation in sensor networks. The mutual information between the measurements of sensors and the estimated distribution of the target state is considered as the information utility function to evaluate the information contributions of sensors. Only those sensors with larger mutual information are selected to participate in Kalman filtering iterations. Then the geographic routing mechanism is utilized to visit these selected sensors sequentially and to set up a path to transport the state estimation information to the sink node. Simulation results show that the information-driven sensor selection algorithm has excellent estimation performance.
A distributed link-based IP paging method is proposed to enhance the scalability and flexibility of traditional IP paging. A semi-active state of mobile node (MN) is introduced in hierarchical mobile IPv6 (HMIPv6) network. Then, a dynamic paging agent (PA) designation and paging link establishment approach is proposed, it would decrease the number of redundant IP paging messages and balance the network signaling traffic. Theoretical analysis for overall signaling load demonstrates that the link-based paging method with moderate paging link length could significantly reduce the paging signaling cost and improve the network performance.
The ergodic capacity of independent and identically distributed multiple-input multiple-output (MIMO) flat Rayleigh fading channels is investigated when the channel state information is assumed to be unknown at the transmitter but perfectly known at the receiver. Firstly, a simple closed-form MIMO channel capacity formula is derived by using the eigenvalue distribution of Wishart matrix. An asymptotic bound of MIMO channel capacity at high signal-to-noise ratio (SNR) is acquired on the basis of the formula. The bound analytically shows that the capacity is asymptotically linear in the logarithm of SNR and the minimum of the number of transmit and receive antennas with the growth of SNR. Finally, the proposed capacity formula and asymptotic bound are justified by computer simulation.
A new kind of perfect discrete signal with good odd-periodic correlation function is presented. It is odd-periodic perfect almost binary sequence pair. The elements of each sequence in odd-periodic perfect almost binary sequence pair are “1” or “-1” with exception of a single zero element, and odd-periodic perfect almost binary sequence pair possess a perfect odd-autocorrelation function. The transformation features and Fourier spectrum of odd-periodic perfect almost binary sequence pair are studied. Some combined admissibility conditions are also given out. It is found that odd-periodic perfect almost binary sequence pair spreads the existing range of odd-periodic perfect almost binary sequence and odd-periodic perfect almost binary sequence is a special case when the two sequences in the odd-periodic perfect almost binary sequence pair are same.
A near maximum-likelihood (ML) multiuser detection algorithm based on unconstrained optimization approach is proposed for code-division multiple access (CDMA) systems. By employing the proposed algorithm, ML detection regarded as a combinatorial optimization problem, is transformed to an unconstrained optimization problem. The detected symbols are obtained by approximating the solution of the aforementioned unconstrained optimization problem. Simulation results show that the performance of the proposed algorithm is very close to that of the ML detection algorithm over both additive white Gaussian noise (AWGN）and time-varying multipath fading channels, meanwhile its computational complexity is comparable with that of the conventional linear detection algorithms, especially when the number of users is high.
LIU Xue-yong, YANG Da-cheng
A downlink admission control (AC) algorithm is proposed in code division multiple access （CDMA）systems, that is based on multi-cell transmitted power raised estimation. The transmitted power raised in the adjacent base stations is taken into account as well as in the serving one when a new call is arrived. A method is derived to estimate the transmitted power in the adjacent base stations. Simulation results show that under non-homogeneous conditions, the proposed algorithm reduces the probability of wrong admission, accordingly the throughput is increased.
Aiming at multi-carrier system, a utility-based radio resource scheduling method, named as Multi-carrier gradient scheduling algorithm with minimum/maximum rate constraints (GMR) is proposed. As an extension of GMR, it can be used in beyond tree generation (3G) wireless communication system for multiuser scheduling. Analysis and simulation results show that the algorithm can provide soft quality of service (QoS) guarantee with good performance and low complexity.
In vertical-Bell laboratory layered space-time (V-BLAST) systems, the detection of received signal needs rich scattering channel environment, otherwise the system bit error rate (BER) performance descends seriously. A transmit antenna selection algorithm based on V-BLAST orthogonal frequency division multiplexing (OFDM) systems is proposed to solve this problem in this paper. This algorithm selects the transmit antenna subset that will maximize the minimum signal-to-noise-plus-interference ratio (SNIR) on each sub-carrier. Theoretical analysis and computer simulation results show that the system BER performance is significantly improved by this algorithm.
Energy of nodes in wireless sensor networks (WSNs) was spent on delivering the packets mostly. In order to decrease the number of packets, but not increase the time delay simultaneously, a model of data dissemination based on confidence coefficient was presented. Confidence coefficient was generated by the node based on the data sensed, and represented the authenticity and importance of the data. A backoff algorithm and a transmission filter based on the confidence coefficient were designed also. Extensive simulations testified that the model was effective in decreasing energy consumption of the node and time delay of the important data.
In order to implement the differentiated, customized, quality of service (QoS) guaranteed service in IP DiffServ network, the layered service-oriented model for DiffServ is improved. An integral IP service implementation mechanism based on service level agreement (SLA) is proposed. thus, the problem of mapping customer service level specification （SLS） to provider SLS is solved. An IP service implementation process based on the above mechanism is described. Implementation of a prototype verifies that validity of the mechanism.
A query refinement scheme, which synthesizes the synonymic relation and the semantic association, is presented. By analyzing the synonymic characteristic of the key words and the intensity of semantic association among the ontology instances, the accuracy and completeness of the mapping from key word to ontology entities can be improved. A query refinement system is designed and implemented. The experimentation results show the system can optimize query input efficiently.
A fuzzy logic based security-level (FLSL) routing protocol is proposed. The basic idea of the FLSL routing protocol is to utilize the “local multicast” mechanism and the security-level to select the most secure route. The proposed algorithm of security-level is an adaptive fuzzy logic based algorithm that can adapt itself with the dynamic conditions of Ad hoc networks. The FLSL routing protocol will improve the security of Ad hoc networks
A low-complexity blind symbol-timing synchronization scheme applicable to zero prefix-orthogonal frequency-division multiplexing（ZP-OFDM ）systems is presented. The proposed method is based on zero prefix（ZP） power collection in the ZP-OFDM symbols whose ZP average power distribute regularly in the slide windows. The synchronization schemes in both Gauss channel and multipath Rayleigh fading channel are investigated. Average power distribution of the received signal in multipath Rayleigh fading channel is analysed in detail in order that symbol synchronizes accurately. The relation of synchronization performance and the window’s width is presented. A multi-slide-windows method is designed in order to improve the performance of synchronization. Final computer results also demonstrate the superior performance of the new method in both Gauss channel and multipath Rayleigh fading channel.
Unique problems that hybrid automatic repeat request (HARQ) encounter in Time Division Duplex- high speed downlink packet access (TDD-HSDPA) systems are analyzed, especially when smart antennas are introduced. Accordingly, a novel mechanism combining HARQ with adaptive modulation and coding (AMC) is proposed. Dynamic system level simulator based on OPNET software is established to investigate the performance gain of the mechanism. Simulation results indicate that the scheme can reduce system block error rate (BLER) significantly and enhance system throughput.
According to the feature of mobile Internet over wireless link, a new handover scheme for mobile wireless IP networks is presented based on the idea of cross-layer design. The proposed scheme will forward the packets to the mobile host in the network layer with multicast protocol and employ the trigger information from the link layer in order to construct the multicast tree. The numerical analysis discloses that the proposed scheme can shorten more handover delay and reduce the packets loss ratio more efficiently than Mobile IP protocol and Hierarchical Mobile IP protocol. The signaling cost during the handover also decreases obviously in the proposed scheme so that plenty of radio resource is saved.
A new architecture of power generation circuit is proposed based on charge pump principle. Then an algorithm is designed to simplify the power generation circuit architecture. Finally, using the novel architecture and algorithm, an example of power generation circuit applied in ultra high frequency（UHF）passive transponder integrated circuit (IC) is given. The results prove that the architecture and algorithm simplify power generation circuits and enhance the circuit efficiency when providing the same output voltage.
The performance of vertical bell labs layered space-time (V-BLAST) over receive correlated Rayleigh fading channel is investigated. The squared Euclidean distance is observed to be the sum of weighted-chi-squared-distributed random variable. Based on the observation, a new exact expression of the pairwise error probability (PEP) is presented . The asymptotic result of the PEP for high signal-to-noise ration (SNR) is used to quantify the loss of the diversity order and the penalty of SNR. It is shown that the loss of diversity order equals to the difference of the number of receiver antennas and the rank of receive correlation matrix, and, under that assumption that the receive correlation matrix has full rank, the penalty of SNR is jointly determined by the determinant of the receive correlation matrix and the number of receive antennas. Simulation results are given to corroborate the theoretical analysis.