Search

In wireless communication, radio access is a key and important technology. Cognitive Radio (CR) and non-orthogonal multiple access (NOMA) are two promising technologies for next generation networks. The combination of CR and NOMA can improve spectral efficiency and outage probability. In this paper, we introduce an underlay CR inspired NOMA system, in which we use a coordinate direct and relay transmission scheme for data transmission. A relay is used to reduce the effect of co-channel interference in CR inspired NOMA system. The relay in this article functions as decode and forward. In this article, different from other existing literature, we use a new scheme for decoding primary and secondary users symbols in a way that increases system performance, improves outage probability and energy efficiency. In this method, in the first phase, the primary transmitter broadcasts the symbol of the primary user and the secondary transmitter broadcast a superimposed symbol. In the second phase, the relay makes a decision based on the detection result based on the proposed plan and transmits the symbols. The primary and secondary users combine the first and second phase signals to improve the outage probability and increase system performance. Based on this, we introduce a signal-to- interference plus noise ratio combined, the use of this method improves the probability of outage compared to the other designs in this article. In this article, the closed form for the outage probabilities of the primary and secondary users has been extracted, as well as the outage probability at high signal-to-noise ratio (SNR)s and the asymptotic expressions for the outage probabilities of the primary and secondary users. Also, energy efficiency and throughput have been extracted for and it has been shown that choosing the optimal power allocation coefficient is important for increasing energy efficiency and throughput. Also, the simulation results show the high performance of the method proposed in this article compared to other designs. [ABSTRACT FROM AUTHOR]

In the multi hop communication of wireless sensor networks, relay stations are used to realize remote transmission. In order to avoid the air data repeating collision problem and multi-path retransmission problem of wireless signals sent by relay nodes, this paper proposes a relaying algorithm using dual buffer pool. The node buffer pool is added in the node to store the package source identifier and packet count pairs, the package buffer pool is added to the package to store paths in transmission. First, after the package is received from radio, the node compares the pairs of the SID and Count in the node buffer pool with the pairs of the package source identifier and package count in the package. If there are pairs, the package is discarded, otherwise the package source identifier and package count are added into the node buffer pool. Next step, if the node identifier is equal to the destination byte DID in package, the package will be processed in the node and terminated transmission, otherwise the package will be continued to process. Then the node compares the node identifier with the package buffer pool bytes. If there is the node identifier in the package pool, the package will be discarded, otherwise the relay node stores its own node identifier into the packet buffer pool to create a new package and transmit forwards. The algorithm is implemented on CC2530 chip and relaying experiments of wireless sensor network are carried out. The results show that the algorithm can achieve relay forwarding and avoid duplicating forwarding data collision and avoid multipaths duplicate forwarding. [ABSTRACT FROM AUTHOR]

The huge increase in the communication network rate has made the application fields and scenarios for vehicular ad hoc networks more abundant and diversified and proposed more requirements for the efficiency and quality of data transmission. To improve the limited communication distance and poor communication quality of the Internet of Vehicles (IoV), an optimal intelligent routing algorithm is proposed in this paper. Combined multi-weight decision algorithm with the greedy perimeter stateless routing protocol, designed and evaluated standardized function for link stability. Linear additive weighting is used to optimize link stability and distance to improve the packet delivery rate of the IoV. The blockchain system is used as the storage structure for relay data, and the smart contract incentive algorithm based on machine learning is used to encourage relay vehicles to provide more communication bandwidth for data packet transmission. The proposed scheme is simulated and analyzed under different scenarios and different parameters. The experimental results demonstrate that the proposed scheme can effectively reduce the packet loss rate and improve system performance.

Unmanned Aerial Vehicles (UAVs) can assist Internet of Things (IoT) systems in collecting data from sensor nodes due to their high flexibility and ease of deployment. However, in existing UAV-assisted IoTs, there is neither mission overlap nor mission collaboration between UAVs, which requires all UAVs to return to the base station to offload the collected data. This results in significant latency in data transmission. Therefore, we propose a proximity-remote region collaborative data collection scheme to overcome this problem. In this scheme, we first divide the mission region into the proximity region and the remote region, and deploy an appropriate ratio of UAVs in each region for data collection. Second, we balance the flight paths of UAVs in different regions by updating the partition. Finally, we achieve seamless relay transmission between UAVs by selecting relay points, modifying UAV flight paths, and adjusting flight speed and take-off points. Through the above process, data collected from the remote region can rapidly reach the base station through seamless collaborative relays between UAVs. Extensive experimental results have shown that the proposed scheme can effectively reduce the data transmission latency of the system compared to existing data collection schemes. [ABSTRACT FROM AUTHOR]