Power Switching Protocol for Two-way Relaying Network under Hardware Impairments

In this paper, we analyze the impact of hardware impairments at relay node and source node (i.e. imperfect nodes) on network performance by evaluating outage probability based on the effective signal to noise and distortion ratio (SNDR). Especially, we propose energy harvesting protocol at the relay and source nodes, namely, power switching imperfect relay (PSIR) and power switching imperfect source (PSIS). Aiming to determine the performance of energy constrained network, we first derive closed-form expressions of the outage probability and then the throughput can be maximized in delay-limited transmission mode. The simulation results provide practical insights into the impacts of hardware impairments and power switching factors of the energy harvesting protocol on the performance of energy harvesting enabled two-way relaying network

Secrecy performance of TAS/SC-based multi-hop harvest-to-transmit cognitive WSNs under joint constraint of interference and hardware imperfection

In this paper, we evaluate the secrecy performance of multi-hop cognitive wireless sensor networks (WSNs). In the secondary network, a source transmits its data to a destination via the multi-hop relaying model using the transmit antenna selection (TAS)/selection combining (SC) technique at each hop, in the presence of an eavesdropper who wants to receive the data illegally. The secondary transmitters, including the source and intermediate relays, have to harvest energy from radio-frequency signals of a power beacon for transmitting the source data. Moreover, their transmit power must be adjusted to satisfy the quality of service (QoS) of the primary network. Under the joint impact of hardware imperfection and interference constraint, expressions for the transmit power for the secondary transmitters are derived. We also derive exact and asymptotic expressions of secrecy outage probability (SOP) and probability of non-zero secrecy capacity (PNSC) for the proposed protocol over Rayleigh fading channel. The derivations are then verified by Monte Carlo simulations.Web of Science195art. no. 116

マルチホップ無線ネットワークの特性解析に関する研究

九州工業大学博士学位論文 学位記番号:情工博甲第309号 学位授与年月日:平成28年3月25日1 Introduction||2 Impact of Transceiver Hardware Impairments on Cognitive Network||3 Case study: Two-Way Cognitive Relay in RF Energy HarvestingWireless Sensor Network||4 Soft Information Relaying Protocol||5 Overall Conclusion and FutureWorkWireless communication has been considered as the most efficient mean of data transmission. We have been witnessed the breakthrough of wireless communication era in many manifolds, such as speech, coverage area, and stability. However, frequency bands, the resource to convey information wirelessly, are limited and expensive to be granted usage licenses. Attaining the goals of ubiquitous wireless devices will require the future wireless networks stepping forward to overcome the scarcity and expensiveness of wireless frequency bands. Thus, the future wireless networks should evolve to utilize wireless frequencies more efficiently, such as cognitive relay network where non-license users are able to transmit data in the same frequency band that officially allocated to primary users. Subsequently, the transmit power of users in a cognitive network is limited and the performance is vulnerable to impairments of transceiver hardware. This dissertation aims to analyze the performance of the cognitive relay network under the impact of transceiver hardware impairments. A case study of two-way cognitive relay network is given for further investigate the impact of transceiver hardware impairments on end-to-end outage performance and throughput. Furthermore, we provide a new relaying scheme in order to lessen the impact of transceiver hardware impairment and further boost the system performance. For the purposes, this dissertation is organized into five (5) chapters. Chapter 1: Introduction. In this chapter, multihop wireless networks and the performance metrics are overviewed. In particular, the relay networks and cognitive relay networks are presented. Moreover, the general model of the practical transceiver hardware impairment is detailed for further analysis. Chapter 2: The impact of transceiver hardware impairments on cognitive relay networks. By using the general hardware impairment model for the received signal, the closed forms of outage probability of the relay network with decode-and-forward (DF) and amplify-and-forward (AF) under the impact of transceiver hardware imperfection are derived. Based on these results, we provide further discussion on transceiver hardware selection guideline. Chapter 3: Case study: two-way cognitive relaying in energy harvesting wireless sensor networks. A two-way relay wireless sensor network equipped with RF energy harvesting node is introduced. This network is aimed to be implemented in hazardous or remote areas where power supply for the relay node is difficult to maintain. In this chapter, we consider four configurations of the network with formed by combining two bidirectional relaying protocols and two wireless power transfer policies. The detailed performance analysis of outage probability and throughput of the case-study network with four configurations are presented. Based on the analysis, we provide performance comparison between the four and suggest the network configuration with the best performance. Chapter 4: Soft information relaying protocol. The soft information relaying protocol is proposed and analyzed. The analysis shows that this relaying protocol can gradually reduce the impact of transceiver hardware impairment on cognitive relay networks. Hence, soft relaying protocol is considered as a solution for cognitive relay network with cost-effective wireless transceiver devices. Chapter 5: Overall conclusion. An overall summary of the works presented in the above is provided in this chapter. Moreover, the future related work is also discussed. The results in this dissertation acknowledge the impact of transceiver hardware impairment by presenting the reduction of outage probability and throughput of the cognitive relay network. It puts forward the consideration of including the impact of transceiver hardware impairments on wireless network performance analysis, especially for the cognitive networks of which the transmit power is limited. Furthermore, a new relaying protocol, namely soft information relaying protocol, is proposed as a solution to lessen the impact of transceiver hardware impairment. The analysis shows that the impact of transceiver hardware impairment in cognitive relay network is reduced in compared to conventional relaying schemes. As a final point, we have provided a full picture of performance analysis for the cognitive relay network under the impact of transceiver hardware imperfection and the solution to reduce the performance loss by applying soft information relaying scheme. This research would contribute to boost the development of cognitive relay networks where frequency bands are used more efficiently

Wireless-Powered Communication Assisted by Two-Way Relay with Interference Alignment Underlaying Cognitive Radio Network

This study investigates the outage performance of an under-laying wireless-powered secondary system that reuses the primary users (PU) spectrum in a multiple-input multiple-output (MIMO) cognitive radio (CR) network. Each secondary user (SU) harvests energy and receives information simultaneously by applying power splitting (PS) protocol. The communication between SUs is aided by a two-way (TW) decode and forward (DF) relay. We formulate a problem to design the PS ratios at SUs, the power control factor at the secondary relay, and beamforming matrices at all nodes to minimize the secondary network's outage probability. To address this problem, we propose a two-step solution. The first step establishes closedform expressions for the PS ratios at each SU and secondary relay's power control factor. Furthermore, in the second step, interference alignment (IA) is used to design proper precoding and decoding matrices for managing the interference between secondary and primary networks. We choose IA matrices based on the minimum mean square error (MMSE) iterative algorithm. The simulation results demonstrate a significant decrease in the outage probability for the proposed scheme compared to the benchmark schemes, with an average reduction of more than two orders of magnitude achieved