Search

Copyright of Electric Power is the property of Electric Power Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To solve the current problems of inefficiency, low utilization of intensive network resources, and high system cost in handling multi-user applications, a multi-user fine-grained task offloading scheduling approach under cloud-edge-end collaboration was proposed. Latency, energy consumption, and server rental costs were jointly considered. Application tasks were firstly divided and subtask priorities were designed. Then, a multi-user subtask scheduling scheme was proposed and an improved simulated annealing particle swarm algorithm was designed to minimize the total system cost to achieve the optimal offloading decision. Experimental results show that the proposed method reduces the total cost by at least 12.28% and 7.42% compared to other methods such as particle swarm and simulated annealing binary particle swarm, respectively.

Copyright of Telecommunications Science is the property of Beijing Xintong Media Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To solve the channel acquisition overhead problem of frequency division duplex massive MIMO, for the typical scenario of zero-forcing (ZF) precoding at the base station with users’ quality of service guarantee, a supervisory mechanism for the signal-to-interference-and-noise ratio (SINR) was introduced, and a multi-user antenna-by-antenna interleaved training scheme was designed.Then, considering the additional time overhead introduced by the interleaved training, a multi-user interleaved training scheme based on antenna grouping was designed.Closed-form expressions of the average training length, transmission success rate, and average effective sum spectrum efficiency were derived for the proposed schemes.Theoretical and simulation results reveal the impact of transmit power, SINR threshold, user number, group length, and the error level of channel on the performance of the proposed schemes, and demonstrate that the proposed schemes significantly reduce the pilot overhead and improve the transmission success rate compared to the full and partial training.

Copyright of Journal on Communication / Tongxin Xuebao is the property of Journal on Communications Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The k-dominated skyline algorithm weakens the domination relationship between data points and is more suitable for high-dimensional data. k-dominated skyline bodies are suitable for multiple users to query with the k-dominated skyline algorithm, but the existing solution algorithms need to be improved in terms of time efficiency and code scalability. Therefore, this paper proposes an optimization algorithm for solving k-dominated skyline bodies. This algorithm stores the candidate set and the intermediate set for each user separately, and stores the non-k-dominated skyline points in the candidate set to the intermediate set of the corresponding user in the order of appearance of data points in the two sets during the k-domination checking process, so that the next user can filter and use them, which can reduce the number of comparisons between data points, avoids double counting, and improve query efficiency. A multi-user k-dominated skyline body parallel solving algorithm is also proposed, which effectively reduces the comparison time of data points through the Apache Flink parallel processing framework. The theoretical study and experimental data show that the proposed algorithm is highly efficient and can handle the multi-user k-dominated skyline problem well. [ABSTRACT FROM AUTHOR]

Intelligent reflecting surface (IRS) can achieve unprecedented channel capacity gains by reconfiguring the wireless propagation environment smartly. The channel capacity is maximized by jointly optimizing the power-constrained precoder at the base station and the unit modulus-constrained phase shifter at the IRS in the IRS-assisted multi-user downlink communication. Aiming at the resulting non-deterministic polynomial hard problem, it is converted into an equivalent problem then the alternative optimization algorithm is used to solve the precoding matrix and phase shift vector. The problem can be converted to a second-order cone programming problem that can be solved by adopting standard optimization packages while the phase shifts vector fixing. The unit modulus constraint is the difficulty to solve this problem, it is decided to embed it into the search space. Then the Riemannian trust-region (RTR) algorithm is proposed to solve this problem while fixing the precoding matrix. Simulation results show that, compared with the existing approaches, RTR algorithm not only has better performance gains but also faster convergence speed. [ABSTRACT FROM AUTHOR]

To solve the problems of single-user search, single-keyword search, high computational cost and low-security level of ciphertext data retrieval in the industrial Internet of things environment, a certificateless ciphertext retrieval scheme with multi-user and multi-keyword based on cloud-edge collaboration was proposed.A user access permissions table was set and once encryption algorithm was executed to realize multi-user search and update users’ access permissions.A cloud-side collaborative computing model was introduced to match keyword ciphertext and keyword trapdoor efficiently by a linear scanning method when the keyword ciphertext does not entirely contain the search keyword.Key escrow and certificate management problems were solved by utilizing certificateless encryption system.Keyword ciphertext authentication was ensured by using digital signature technology.The security analysis results show that the proposed scheme can resist internal keyword guessing attacks under the random oracle model.Simulation results show that the proposed scheme has higher computational efficiency compared with similar schemes.

Copyright of Journal of South China Normal University (Natural Science Edition) / Huanan Shifan Daxue Xuebao (Ziran Kexue Ban) is the property of Journal of South China Normal University (Natural Science Edition) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wi-Fi 6 was the new name of IEEE 802.11ax by the Wi-Fi Alliance to facilitate the promotion of new Wi-Fi technology.Wi-Fi 6 technology focused on improving multi-user performance and efficiency in dense deployment scenario.Introducing OFDMA, UL MU-MIMO and other multi-user collaboration technologies, greatly increases system capacity and reduces transmission delay.The principles of OFDMA, MU-MIMO, MU-RTS/CTS technologies were described, the communication process in multi-user scenario was introduced in detail, and the UL and DL simultaneous user numbers of Wi-Fi 6 were analyzed in theory.Finally, the application potential of Wi-Fi 6 were discussed.

Copyright of Journal on Communication / Tongxin Xuebao is the property of Journal on Communications Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In a frequency division duplex communication system,precoding at the base station usually requires terminal feedback channel state information.In a distributed array system,the channel conditions between the terminal and different access nodes in the cell are different because multiple access nodes are arranged at different locations in the cell.When the resources for feedback channel state information are limited,the allocation method of feedback bit needs to be optimized to improve the overall performance of the system.In a multi-user distributed array system,an access node selection method based on distance threshold was adopted.Based on this method,the quantization characteristics of the random vector quantization codebook and the Taylor expansion method were used to derive the system quantization capacity loss,and then an approximate expression was given.Based on this expression,a feedback bit allocation method was proposed.Compared with other allocation methods,the method of this paper was more universal because it did not limit the number of access nodes selected by the user.The simulation results show that the strategy proposed is superior to the traditional equal-bit allocation scheme and can obtain better performance when the feedback resources are limited.

The traditional privacy-preserving image retrieval schemes not only bring large computational and communication overhead,but also cannot protect the image and query privacy in multi-user scenarios.To solve above problems,an efficient privacy-preserving content-based image retrieval scheme was proposed in multi-user scenarios.The scheme used Euclidean distance comparison technique to rank the pictures according to similarity of picture feature vectors and return top-k returned.Meanwhile,the efficient key conversion protocol designed in proposed image retrieval scheme allowed each search user to generate queries based on his own private key so that he can retrieval encrypted images generated by different data owners.Strict security analysis shows that the user privacy and cloud data security can be well protected during the image retrieval process,and the performance analysis using real-world dataset shows that the proposed image retrieval scheme is efficient and feasible in practical applications.

Copyright of Telecommunications Science is the property of Beijing Xintong Media Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Telecommunications Science is the property of Beijing Xintong Media Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Focusing on the multi-user satellite communication system, the outage performance of the system under the condition of the amplify-and-forward (AF) protocol based on the threshold judgment is analyzed. Firstly, taking the satellite antenna gain and satellite path loss into account, assuming that the small scale fading of satellite link obeys shadowed-Rician (SR) distribution, the closed-form expression of outage probability for the multi-user satellite communication system is derived. Then, in order to further analyze the performance of the system, the asymptotic expression of the outage probability at high signal noise ratio (SNR) is derived, and the analytic expressions of the diversity order and coding gain of the system are obtained. Finally, the computer simulations verify the validity of the theoretical analysis, and analyze the influence of the number of users and channel parameters on the performance for the multi-user satellite communication system, which provides a guide and basis for the design of actual system. [ABSTRACT FROM AUTHOR]

In the large-scale MU-MISO system, this paper studied the spectral efficiency affected by the channel and power allocation in spatially correlated channels. Firstly, it derived the transmit correlation matrix of the user from steering matrix which was determined by the wave path difference of the transmission signal. Then it established spatial correlation channel under the large-scale shadow fading and the scattering environment with Gaussian distribution. Based on the spatial correlation channel, it simulated the precoding which could reduce the interference between multiple users for the spectral efficiency performance. Finally, this paper proposed a power allocation algorithm that made the spectrum efficiency maximized in the scenario where the transmit power was limited and signal to interference plus noise ratio of each user was limited in receive signal. The simulation shows that the spectral efficiency of RZF precoding in spatially correlated channels is better than that of MRT precoding. And compared with the average power allocation, the spectral efficiency with the proposed algorithm which has strong theoretical and practical significance has the improvement. [ABSTRACT FROM AUTHOR]

In the searchable encryption services, data owners wish to store different data ciphertexts and keyword indexes on different servers, so as to avoid centralized search of servers and infer the ciphertext information. A multi-server multi-keyword multi-user searchable encryption scheme under public channel is proposed by combining multi-user searchable encryption and multi-server features. This scheme allows data owners and users use the cloud servers' public keys to generate ciphertext indexes and search trapdoors, thereby satisfying the transmission under public channel and reducing the communication cost. The analysis results show that the proposal has lower communication cost. In the random oracle model, the proposed scheme is ciphertext index indistinguishable under the adaptive selection of keyword attacks in the decisional Diffie-Hellman problem. [ABSTRACT FROM AUTHOR]

Location recommendation is an important application of location-based social network, Focused on the planning requirement for multi-user group social activities in urban area, and taking into account of urban road accessibility and user's time-cost of participation in activities, based on the characteristics of urban road network structure and navigation route planning, an algorithm for multi-user location recommendation has been suggested, in which the position is recommended in polygon region that is automatically recognized and constructed by making use of specific points in inter-user navigation route in support of map application programming interface, in order to balance the accessibility and time-cost from multi-user to recom mended location. The validity of the suggested approach has been verified by a test system developed by the authors, this method can provide an effective location recommendation scheme for urban multi-user collective activities on location-based social networks. [ABSTRACT FROM AUTHOR]

Copyright of Journal on Communication / Tongxin Xuebao is the property of Journal on Communications Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Chongqing University of Posts & Telecommunications (Natural Science Edition) is the property of Chongqing University of Posts & Telecommunications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Resource allocation problem was investigated for downlink multi-user MIMO-OFDM systems.A QoE (quality of experience) utility function was given according to the characteristics of real-time (RT) and non real-time (NRT) ser-vices,and then a RT ＆amp; NRT QoE utility function-based cross-layer resource allocation algorithm was proposed.The al-gorithm firstly used the designed utility function to calculate the delta QoE,which was offered by users got resource.Secondly,it classified users according to their delta QoE and then allocated time-frequency blocks.Thirdly,it optimized the power allocation result by implementing pseudo water flooding power allocation.Simulation results show that com-pared with the existing algorithm,the proposed algorithm is better in the user average QoE,average packet delay to real time services,average packet lost rate to non real time services as well as sum throughput of system.

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Single carrier frequency domain equalization (SCFDE) joint beamforming in frequency selective multiple input multiple output (MIMO) channels under the multi-user scenario was analyzed.Firstly,the frequency domain beamforming was transformed to a time domain filtering beamforming.By using the time domain model,the signal to interference plus noise(SINR)expression of every receiver at the decision point was shown after the frequency domain minimum mean square error(MMSE)equalization.Under a given quality of service(QoS)constraint of every receiver,the optimal beamforming coefficients minimizing the total transmitted power from all transmitters were found through solving a convex semidefinite programming (SDP) problem relaxed from a nonconvex quadratically constrained quadratic programming(QCQP)problem.Simulation demonstrates that the total transmitted power from all transmitters varies regularly with different settings deployed by the model.

Using the WIFI wireless communication technology, the ARM Cortex A8 embedded system, TCP/IP protocol and WLAN monitoring technology, we design a control system of multi-user wireless projection system on Android. Establishing wireless communication between the client and the wireless projector gateway by WIFI wireless communication technology can solve the constraints of data line, and it is greatly convenient for cable projector users to use wireless projection function. The proposed system with one leader and multi-followers can implement multi-user and multi-platform wireless projection by WLAN, and it is suitable for PCs and Android mobile devices. In addition, we also describe in detail the wireless projection gateway and the design of wireless projection management software. Test results show that the system meets operating requirements. [ABSTRACT FROM AUTHOR]

Coordinated multi-point (CoMP) joint transmission (JT) is an effective technique to improve the quality of services for cell edge user. In JT, multiple points precode jointly to reduce the interference of the cell edge, thereby improve the spectral efficiency. Combining orthogonal projection (OP) with sorted QR decomposition (SQRD), the paper proposes two JT methods which are respectively named as OP-ZF-SQRD and OP-MMSE-SQRD. Both methods use OP to eliminate multi-user interference, and decompose the multi-user system into multiple parallel single-user systems without interference. Then, ZF-SQRD or MMSE-SQRD is applied to each single-user system separately. Simulation results show that compared to joint transmitter zero forcing (JT-ZF) and block diagonalization (BD) methods, the two proposed methods have obvious advantages in performance. Meanwhile, the two proposed methods can not only eliminate multi-user interference but also mitigate multi-stream interference of each user effectively, thereby they improve the quality of services and the spectral efficiency for the cell edge. [ABSTRACT FROM AUTHOR]