Daniyal Munir

Information Processing and Wireless Energy Harvesting in Two-Way Amplify-and-Forward Relay Networks

Wireless energy harvesting is an efficient way to prolong the lifetime of energy constrained networks. In this paper, a two-way amplify-and-forward (AF) based relay network is considered, where two communicating nodes concurrently transmit there information signals to a relay node using time switching based relaying protocol (TSR). The relay node is energy constrained and therefore it first harvests the energy from the received radio frequency (RF) signals. After successful energy harvesting the relay utilizes the harvested energy to amplify and forward the received information signal to its destination. We derive the analytical expression for outage probability and achievable throughput at the receiving nodes. Our numerical results verify our analytical derivation and shows the effect of different system parameters on achievable throughput at receiving nodes.

Reliable cooperative scheme for public safety services in LTE-A networks

In order to enable effective public safety services in challenged environments, 3rd Generation Partnership Program is considering the use of device-to-device (D2D) communications. D2D communications can be ideal in various emergency situations where the conventional network services get suspended. We propose a D2D-based user equipment (UE) relaying process to support the out-of-range isolated UEs. The main idea is to allow UEs that have active connections with eNB to exchange data with the isolated UEs over direct D2D links. This paper proposes a mechanism that enables an ordinary UE to serve as a relay for the isolated UEs, considering the D2D link capacity and the relays radial velocity. We define the complete procedure of establishing a reliable relay link between UEs in public safety environments and analyse its performance. Copyright

Selection of relay UE with energy harvesting capabilities in public safety environment

Relaying is a widely proposed solution for multi-hop communication in PS environments. However, the selected relay is energy constrained and cannot go on indefinitely. Energy harvesting can solve this problem and make multi-hop D2D communication a viable solution for PS services. In this paper, selection of energy harvesting relay has been studied for device-to-device (D2D) communications. Public safety environment has been considered, where some user equipments (UE) are located out of the coverage area of eNodeB (eNB). For out of the coverage UEs, communication with the eNB is possible through an intermediate relay UE and selection of those intermediate relay UEs is the main focus of this work. Based on D2D link between potential relay UE and out of coverage UEs and estimated harvested energy at potential relay UE, a relay UE is selected to support out of coverage UEs. The relay-based approach enables D2D communications to incorporate cellular and ad hoc operations based on the network availability. The energy harvesting parameter at the relay UE make it unique, which is used to extend the life of rapidly drained battery of a relay UE. The effect of energy harvesting and D2D link quality on the selection of a relay UE has been topics of focus in this work. The proposed scheme is evaluated through system level simulations.

Selection of UE relay considering QoS class for public safety services in LTE-A network

Introduction of Device-to-Device (D2D) communication in public safety (PS) environments has been well investigated by 3rd Generation Partnership Project (3GPP). The main target is to provide communication services to user equipments (UE) in the disaster struck area with the help of ordinary UEs over D2D links. UE-relaying is one of the most important application of D2D communication especially in PS environment. While selecting this type of relay, several factors have to be considered prior to the selection process. Previously, only transmission rates were considered for the selection of UE relay on the basis of received signal strength. We propose a UE relay selection scheme in this article taking into account the quality of service (QoS) class. For that, we consider two important factors which greatly affect the communication process specially in cellular networks; data rates and radial velocity. We use weighted sum model as a tool for selecting most appropriate UE relay. The efficiency of the relay selection process is also increased and we evaluate the performance with the help of system level simulations.

Low-power backscatter relay network

This paper proposes a full duplex relay scheme for ambient backscatter devices which require little or no power for operation. The ambient backscatter devices reflect radio signals from ambient sources such as TV tower, FM radio station, etc. Because of the backscattering of radio signals, such devices have small coverage range. To extend the network coverage of such devices, relaying is the most conventional way, which is previously used for extending the coverage range of radio networks such as LTE, WiFi and so on. In this paper, the backscatter devices assist other backscatter devices to relay the information to their destination nodes. Because of the full duplex characteristics at the relaying node, they can send their own information while receiving signals from the source node. We propose the relaying procedure for full duplex backscatter nodes and investigate the its performance in terms of throughput by performing simulations.

Duty Cycle Optimizing for WiFi-based IoT Networks with Energy Harvesting

In this paper, we propose a simple method to optimize the duty-cycle of an IoT network equipped with energy harvesters. The main objective is to achieve Energy Neutral Operation (ENO) so that the devices can operate autonomously for longer periods. We use an exponentially weighted moving-average (EWMA) filter to predict the energy harvested in a single duty-cycle, and adjust the duty-cycle according to the energy required during the active periods. As a case study, we consider the use of the carrier sensing medium access (CSMA) Medium Access Control (MAC) protocol in a data collection application where a WiFi access point investigates a group of IoT devices equipped with energy harvesting circuit. We evaluate the performance of the proposed scheme with the help of simulations. The results show that an optimal configuration of the prediction filter can help to reach the ENO condition and ensure the unlimited lifetime of the network.

Relay Selection Scheme for Cooperative Backscatter Communications Networks

Backscatter communications has become an emerging alternative to replace conventional radio frequency (RF) communications, especially for the internet of things (IoT) networks. Due to its low power and low complexity operations, it is well suited for the implementation of IoT in next generation communications networks. Since backscatter devices operate on the principle of reflecting RF signals, the transmission range of such devices is very small. Relaying has been commonly adopted for extending the communication range of distant devices. An efficient relay selection scheme can significantly improve the signal to noise ratio at the base station. In this paper, we propose a relay selection scheme for an IoT network, where backscatter devices relay information to the base station. The proposed scheme enables out-of-coverage devices to communicate with the base station via backscatter relay devices. We also explain the procedure for obtaining the channel state information for efficient beamforming of signals at the base station in order to achieve improved data rates. Simulation results show that acquiring accurate channel state information can significantly improves the overall data rates of the proposed backscatter relay network. We also show the effect of various system parameters on overall system performance.

Information Processing and Wireless Energy Harvesting in Interference-Aware Public Safety Networks

In a public safety environment, user equipments (UEs) located within the coverage area of evolved NodeB, relay network services to out-of-coverage UEs. However, relay UEs in public safety environments are typically energy constrained and cannot operate indefinitely without recharging. Radio frequency energy harvesting has been proposed as a solution for recharging wireless UEs. In this paper, we propose a scheme for extending the lifetime of a public safety network by wirelessly charging relay UEs. In addition, we propose a relay selection method considering the battery status of relay UEs. The proposed relay selection is defined as a bipartite graph matching problem and the optimal relay is obtained through matching games technique. The proposed scheme not only improves the network lifetime but also extend the network coverage. We also conduct system level simulations to evaluate the performance of the proposed scheme. Simulation results show that the overall performance of the system is improved in terms of achievable throughput and network lifetime.

Integrating RF-powered backscatter with underlay cognitive radio networks

This paper proposes the technique which can improve the data rate of secondary system in radio frequency (RF) powered backscatter cognitive radio networks (CRNs). In previous studies, secondary system cannot transmit data by conventional radio transmission when a channel is busy. However, in our proposed scheme, secondary transmitter (ST) is allowed to transmit data even though the channel is busy. The ST selects the harvest-then-transmit or backscatter mode based on interference at primary receiver (PR). We obtain the maximum data rate of secondary system by optimizing the allocated time of energy harvesting, transmitting and backscattering. We evaluate the performance of proposed scheme through the simulation. The results show the proposed scheme improves the performance of the secondary system in terms of throughput.

A Mechanism on Energy Harvesting and Data Communications in Wi-Fi Network

RF energy harvesting is a novel technology which is used for harvesting energy from the ambient RF resources. In energy harvesting, harvested energy is converted into useful electrical energy to recharge battery of electronic devices. With energy harvesting scheme, there is no need to replace battery, and the device can be recharged without cable line. Although the energy harvesting technique brings the convenience for recharging the devices, the amount of harvested energy is too small to operate device without supplying energy from the wired resource. In this paper, we consider Wi-Fi signals as energy harvesting resource, where Wi-Fi nodes can harvest energy from ambient signals that are being transmitted by the other users. Not only energy harvesting but also data transmission is considered in this paper. In order to achieve simultaneous wireless information and power transfer (SWIPT) switching circuit is proposed. We measure the received signal strength of Wi-Fi signals in the real environment, and our simulation results show harvested energy and throughput of the nodes in Wi-Fi network.