In this letter, we introduce information-guided channel-hopping, a new scheme for high data rate communication over Rayleigh fading channel using multiple transmit antennas. This scheme is proposed based on the fact that the independence character of multi-channel can be used as an additional information transmitting channel, and the maximum likelihood decoding can be achieved in a simple way by decoupling of the signals conveyed by different methods. The analysis results prove that the capacity behavior of this scheme is better than that of the space-time block coding for more than two transmit antennas.

In this paper, a novel transmission strategy, referred to as mapping-varied spatial modulation, is proposed for physical layer security, where the transmitter varies mapping patterns for the radiated information and the antenna information of spatial modulation, based on the instantaneous pattern of legitimate channel quality information that is unknown to eavesdroppers. Therefore, eavesdroppers cannot successfully decode the confidential information and the transmission over the legitimate link is secured from the wire-tap of eavesdroppers, without relying on higher-layer encryption. An important virtue of the proposed transmission strategy is that the transmitter does not need to know eavesdroppers' channels states at all. To further demonstrate the advantage of this scheme, its secrecy rate was formulated for the purpose of facilitating the performance evaluation. Moreover, illustrative numerical results pertaining to the metrics of ergodic secrecy rate and secrecy outage probability not only substantiate the validity of the proposed transmission strategy, but also provide useful references for the system design with the mapping-varied spatial modulation, from the view of physical layer security.

In this paper, a decode-and-forward (DF) short-packet relaying model is developed to achieve timely status updates for intelligent monitoring within the Internet of Things (IoT), where the status updates generated at an IoT device are delivered to a remote server with the aid of a relay in both half-duplex (HD) and full-duplex (FD) modes. To characterise the data freshness of status updates, we exploit the age of information (AoI) as a metric, which is defined as the time elapsed since the generation of the latest successfully decoded status update. The average AoI is formulated and minimised for both HD-DF and FD-DF relaying IoT networks in finite blocklength regime. For the HD-DF relaying, we introduce a perfect approximation of the average AoI to solve the problem of average AoI minimisation with the optimal blocklengths in two phases. For the FD-DF relaying, we propose an iterative algorithm to solve the problem of average AoI minimisation by optimising the relay’s transmit power and the blocklength. Illustrative numerical results not only substantiate the validity of our proposed algorithms, but also provide useful references for the IoT monitoring network design, specifically for the transmit power thresholds at the IoT device and the relay.

Fixed-rate and rateless channel codes are generally treated separately in the related research literature and so, a novice in the field inevitably gets the impression that these channel codes are unrelated. By contrast, in this treatise, we endeavor to further develop a link between the traditional fixed-rate codes and the recently developed rateless codes by delving into their underlying attributes. This joint treatment is beneficial for two principal reasons. First, it facilitates the task of researchers and practitioners, who might be familiar with fixed-rate codes and would like to jump-start their understanding of the recently developed concepts in the rateless reality. Second, it provides grounds for extending the use of the well-understood code-design tools - originally contrived for fixed-rate codes - to the realm of rateless codes. Indeed, these versatile tools proved to be vital in the design of diverse fixed-rate-coded communications systems, and thus our hope is that they will further elucidate the associated performance ramifications of the rateless coded schemes.

Solar insecticidal lamps (SILs) play a vital role in green prevention and control of pests. By embedding SILs in wireless sensor networks (WSNs), we establish a novel agricultural Internet of Things (IoT), referred to as the SIL-IoTs. In practice, the deployment of SIL nodes is determined by the geographical characteristics of an actual farmland, the constraints on the locations of SIL nodes, and the radio-wave propagation in a complex agricultural environment. In this article, we mainly focus on the constrained SIL deployment problem (cSILDP) in a mixed-crop farmland, where the locations used to deploy SIL nodes are a limited set of candidates located on the ridges. We formulate the cSILDP in this Scenario as a connected set cover (CSC) problem and propose a hole-aware node deployment method (HANDM) based on the greedy algorithm to solve the constrained optimization problem. The HANDM is a two-phase method. In the first phase, a novel deployment strategy is utilized to guarantee only a single coverage hole in each iteration, based on which a set of suboptimal locations is found for the deployment of SIL nodes. In the second phase, according to the operations of deletion and fusion, the optimal locations are obtained to meet the requirements on complete coverage and connectivity. Experimental results show that our proposed method achieves better performance than the peer algorithms, specifically in terms of deployment cost.

In the context of multiple-input multiple-output (MIMO) communications, we propose a bit-padding information guided channel hopping (BP-IGCH) scheme which breaks the limitation that the number of transmit antennas has to be a power of two based on the IGCH concept. The proposed scheme prescribes different bit-lengths to be mapped onto the indices of the transmit antennas and then uses padding technique to avoid error propagation. Numerical results and comparisons, on both the capacity and the bit error rate performances, are provided and show the advantage of the proposed scheme. The BP-IGCH scheme not only offers lower complexity to realize the design flexibility, but also achieves better performance.