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This paper investigated the multiple unmanned aerial vehicle (UAV) relays' assisted network in the Internet of Things (IoT) systems enhanced with energy harvesting in order to overcome the largescale fading between source and sink as well as achieve the green cooperative communications, where time switch (TS) and power splitting (PS) strategies were typically applied for UAV relays to implement energy harvesting transmission, which was also selected via signal to noise ratio (SNR) maximization criterion so that the terminal node can obtain the optimal signal. Meanwhile, it was worth noting that the terminal node may be disturbed by aggregated interference caused by dense network signaling interaction in the future 5G/B5G systems. Therefore, after TS and PS protocols designing and utilizing, the closed-form expressions of outage probability and bit error rate (BER) for UAV relay assisted IoT systems suffered from aggregated interference were derived in detail. In addition, the throughput and delay limited state of UAV relay assisted transmission were also analyzed thoroughly. The derivations and analysis results showed that the proposed multi-parameter joint optimization of transmitting power, scaling factor, and UAV relay selection could effectively improve the system throughput and reduce the system outage probability and BER. The simulation experiments verified the effectiveness of the proposed schemes and the correctness of theoretical analysis. INDEX TERMS Unmanned aerial vehicles (UAV), relay assisted, IoT, energy harvesting, protocol design, aggregate interference.

The emergence of wireless body area network (WBAN) technology has brought hope and dawn to solve the problems of population aging, various chronic diseases, and medical facility shortage. The increasing demand for real-time applications in such networks, stimulates many research activities. Designing such a scheme of critical events while preserving the energy efficiency is a challenging task, due to the dynamic of the network topology, severe constraints on the power supply, and the limited computation power. The design of routing protocols becomes an essential part of WBANs and plays an important role in the communication stacks and has a significant impact on the network performance. In this paper, we briefly introduce WBAN and focus on the analysis of the routing protocol, classify, and compare the advantages and disadvantages of various routing protocols. Lastly, we put forward some problems and suggestions, which provides ideas for the follow-up routing design.

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A novel, non‐coherent bit‐level detection scheme is proposed to compensate for the frequency offset efficiently in IEEE 802.15.4 binary phase shift keying (BPSK) receivers. In the proposed scheme, the frequency‐offset estimation process only requires comparison, division, and addition operations. The proposed scheme first creates a suitable estimation‐region division, thus the mathematical approximation tan−1(x) ≈ x is efficiently utilised to simplify the conventional optimal estimation. The frequency offset and signal‐to‐noise ratio conditions do not need a priori knowledge. Simulations demonstrate that the proposed scheme is as reliable as the conventional optimal algorithm, but with a significant reduction of complexity.

We investigate the performance of multi-antenna two-way relay networks, where both amplify-and-forward (AF) and decode-and-forward (DF) relaying strategies are considered. First an antenna selection scheme among all nodes is proposed based on maximizing the worse received signal-to-noise ratio (SNR) of two end users. Then, we derive the probability density function (PDF) and cumulative distribution function (CDF) of the received SNRs of both users. We also obtain the closedform expressions of average bit error rates (BER) and the outage probability of our system. Furthermore, we study the asymptotic behavior of our system when transmitting SNR or the number of antennas is large. The results show that the proposed antenna selection scheme achieves full diversity, and the simulation results closely match to our theoretical analysis. To further improve the spectrum efficiency of the system, a hybrid selection antenna scheme is proposed. Finally, the numerical results show that our scheme outperforms the state of art.Index Terms-Amplify-and-forward, antenna selection, bit error rate, decode-and-forward, outage probability.

In vehicular networks, the selection of the relay-node determines the message dissemination through the vehicle-to-vehicle communication. However, the irregular shape of the curve road makes it difficult to design and analyze the relay-node selection on the curve road. In this paper, a relay-node selection on the curve road is first proposed, which aims to fast message delivery and complete coverage of the curve road, namely the complete relay-node selection. Additionally, after defining a metric of the curving rate, the models are constructed to analyze the performances of our proposal in terms of the message dissemination speed and the packet delivery rate. Simulations on a realistic mountain road are conducted. Moreover, the upto-date relay-node selection methods are adapted to suit the scenario of the curve road for the comparison. The results of the simulations prove the validation of the analytic models and the significant performances of our proposal. The attractive benefits include not only the stable performance against the vehicle density in terms of the message dissemination speed and the packet delivery rate but also the improvements of at least 16.20% gain compared with these adapted methods in terms of the message dissemination speed as well as the packet delivery rate of more than 99.7%. INDEX TERMS Relay-node selection, curve road, vehicle-to-vehicle communication, vehicular networks. DUN CAO received the B.S. degree in communication engineering from Central South University, China, in 2001, the M.S. degree in information systems and communications from Hunan University, China, in 2006, and the Ph.D. degree in vehicle engineering from the