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In-band full-duplex wireless communication, which supports a node to transmit and receive simultaneously in the same frequency band, is receiving growing interest. The latency of packets in an in-band full-duplex wireless network can be significantly lowered by employing effective medium access control. However, queue delay is not considered in current delay performance analysis works, which do not describe the delay of a packet from generation to reception or analyze the ability to support real-time traffic. In this article, an easily expandable three-way handshaking in-band full-duplex medium access control mechanism is proposed, and both queueing delay and access delay are analyzed. Based on an M/G/1 queuing model, the system delay of in-band full-duplex access point from the packet coming to the queue, to its successful reception by the destination user, is provided. Simulation results show that compared with half-duplex access point, in-band full-duplex access point performs excellent low latency.

In underground sensor networks, electronic magnetic waves undergo severe fading due to the challenging environment. Magnetic-induction (MI) communication is a promising alternative physical layer technique for underground sensor networks. In this paper, we solve the intercoil crosstalk in magnetic-induction multiple-input multiple-output (MI MIMO) communication and investigate the channel capacity for underground MI MIMO wireless communication. Firstly, considering mutual induction between each two coils, we analyze the capacity of magnetic-induction channel. Secondly, the channel model of magnetic-induction multiple-input single-output (MISO) is introduced and a novel coil deployment method is proposed to reduce the crosstalk in MI MISO communication. Finally, the capacity of MI MISO communication and MI MIMO communication is deduced by the proposed coil deployment method. Simulation shows that the channel capacity would increase significantly in high SNR regime for underground MI MIMO communication.

Energy is an extremely critical resource for battery-powered wireless sensor networks. Since data transmission typically consumes more energy than any other activities on a sensor node, it is of great importance to design energy optimized routing algorithm to achieve both energy efficiency and energy balance together, in order to prolong the network lifetime. In this paper, with the help of the concept of potential field in physics, we design a distributed energy optimized routing by constructing a hybrid potential field. The goal of this basic approach is to force packets to move toward the sink at the same time to achieve energy balance among neighbors. We adopt the social welfare function from social sciences to predict equality of residual energy of neighbors after selecting different next nodes, which is used to compute the potential value in energy balance potential field. Simulation results show that the algorithm effectively extends the network lifetime, has good performance on energy balance of sensors, and decreases the average hop of data transmission with the increase of the number of sinks, compared with similar algorithms.

A wireless network scenario of bidirectional relaying with imperfect channel side information (CSI) is considered, in which two source nodes intend to exchange information with the help of one relay. The power allocation problem is investigated to minimize the total transmit power subject to constraints on two source nodes' received signal-to-noise-ratios (SNRs). The best relay that minimizes the total transmit power is selected in a multiple relay network. We also present outage analysis when the proposed power allocation is adopted, and a close-form approximation of outage probability is obtained by shrinking the integral interval. Simulation results show that the total transmit power can be substantially decreased and the outage probability is significantly decreased by the proposed power allocation scheme when two source nodes have different QoS requirement.

Wireless sensor nodes are usually powered by batteries and deployed in unmanned outdoors or dangerous regions. So, constrained energy is a prominent feature for wireless sensor networks. Since the radio transceiver typically consumes more energies than any other hardware component on a sensor node, it is of great importance to design energy optimized routing algorithm to prolong network lifetime. In this work, based on analysis of energy consumption for data transceiver, single-hop forwarding scheme is proved to consume less energy than multihop forwarding scheme within the communication range of the source sensor or a current forwarder, using free space energy consumption model. We adopt the social welfare function to predict inequality of residual energy of neighbors after selecting different next hop nodes. Based on energy inequality, the method is designed to compute the degree of energy balance. Parameters such as degree of closeness of node to the shortest path, degree of closeness of node to Sink, and degree of energy balance are put into fuzzy logic system. Fuzzy-logic-based energy optimized routing algorithm is proposed to achieve multiparameter, fuzzy routing decision. Simulation results show that the algorithm effectively extends the network lifetime and has achieved energy efficiency and energy balance together, compared with similar algorithms.