Beijing University of Posts and Telecommunications

About: Beijing University of Posts and Telecommunications is a education organization based out in Beijing, Beijing, China. It is known for research contribution in the topics: MIMO & Quality of service. The organization has 39576 authors who have published 41525 publications receiving 403759 citations. The organization is also known as: BUPT.

A Trust-Based Framework for Fault-Tolerant Data Aggregation in Wireless Multimedia Sensor Networks

Abstract: For wireless multimedia sensor networks (WMSNs) deployed in noisy and unattended environments, it is necessary to establish a comprehensive framework that protects the accuracy of the gathered multimedia information. In this paper, we jointly consider data aggregation, information trust, and fault tolerance to enhance the correctness and trustworthiness of collected information. Based on the multilayer aggregation architecture of WMSNs, we design a trust-based framework for data aggregation with fault tolerance with a goal to reduce the impact of erroneous data and provide measurable trustworthiness for aggregated results. By extracting statistical characteristics from different sources and extending Josang's trust model, we propose how to compute self-data trust opinion, peer node trust opinion, and peer data trust opinion. According to the trust transfer and trust combination rules designed in our framework, we derive the trust opinion of the sink node on the final aggregated result. In particular, this framework can evaluate both discrete data and continuous media streams in WMSNs through a uniform mechanism. Results obtained from both simulation study and experiments on a real WMSN testbed demonstrate the validity and efficiency of our framework, which can significantly improve the quality of multimedia information as well as more precisely evaluate the trustworthiness of collected information.

A Broadband Doherty Power Amplifier Based on Continuous-Mode Technology

Abstract: In this paper, a novel broadband Doherty power amplifier based on the continuous-mode technique (C-DPA) is proposed. The amplifier is focused on manipulating harmonic components in a Doherty power amplifier (DPA) structure to achieve improved bandwidth and efficiency. In a conventional DPA, harmonic isolation is typically required between the two transistors to prevent them from modulating each other at harmonic frequencies. However, as presented in this paper, such isolation is not actually necessary. On the contrary, by allowing the two transistors to modulate each other at harmonic frequencies with the help of a properly designed postharmonic tuning network, a series of highly efficient DPA modes can be created over a continuous frequency band, leading to a broadband C-DPA. Based on the proposed method, an example of a C-DPA working from 1.65 to 2.75 GHz was designed. According to the measured results, the designed C-DPA exhibits a 52%–66% efficiency at a −6 dB power backoff and a power utilization factor higher than 1.08 over the 1.1-GHz band. In addition, when simulated by a 7.5-dB peak-to-average power ratio 20-MHz LTE signal, the example C-DPA exhibits an efficiency of 46%–62% while maintaining an adjacent channel power ratio below −45 dBc after linearization over the full 1.1-GHz band. To the best of our knowledge, this is the first proposed C-DPA and a state-of-the-art performance for broadband DPAs.

Performance Analysis of Impaired SWIPT NOMA Relaying Networks Over Imperfect Weibull Channels

Abstract: This letter considers a simultaneous wireless information and power transfer nonorthogonal multiple access network, where the relay is energy constrained and harvests energy from the source radio frequency signals using a time-switching protocol. Our analysis accounts for imperfect channel state information (ICSI) and residual hardware impairments (RHIs). To characterize the effects of the two imperfections brought in the considered network, the outage probability (OP) and throughput are investigated. More particularly, we derive a lower bound on the OP in closed-form, as well as the asymptotic OP and diversity order. We also investigate the throughput in the delay-limited transmission mode in terms of deriving corresponding expression. It is observed that the performance of system is limited by RHIs and ICSI, which results in error floor for the OP and zero diversity order. In addition, a key conclusion is that by carefully selecting the ratio factor between the energy harvesting and information transmission phases, the throughput can be maximized.

Power Allocation and Subcarrier Pairing Algorithm for Regenerative OFDM Relay System

Abstract: Relayed transmission is a promising technique that helps in attaining broader coverage and in combating the impairment of the wireless channel. Orthogonal frequency division multiplexing (OFDM) technique is promising for the next generation wireless communication system. Therefore, the combination of two techniques named OFDM-relay will be a good candidate technology for future wideband wireless communication. This paper investigates the resource allocation of two-hop regenerative OFDM relay system with/without diversity. Optimization of power allocation (PA) is proposed to maximize the channel capacity and subcarrier pairing strategy is adopted to improve the system performance further. In addition, the resource allocation for multi-hop OFDM system without diversity is also presented. The resource allocation is based on the instantaneous channel state information (ICSI) and aims to maximize the system capacity. The order pairing strategy is proved to be a good choice for multi-hop regenerative OFDM relay system without diversity. The simulation results show that combining with the pairing algorithm, efficient power allocation will greatly improve the system capacity.