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In a Wireless Local Area Network (WLAN), devices have limited battery capacity. To improve the energy efficiency, we propose a new Medium Access Control (MAC) protocol to perform selective energy transfer request based on the amount of residual energy of a device in a WLAN with IEEE 802.11 Distributed Coordination Function (DCF). By supplying the energy only to the device requiring energy harvesting, the deterioration in network throughput during energy harvesting in a wireless network is minimized. We present a new energy Markov chain model to analyze the throughput and the energy efficiency of the proposed method. We confirm that the throughput and the energy efficiency of the proposed method is improved. [ABSTRACT FROM AUTHOR]

The random access procedure in cellular networks suffers from a congestion problem caused by massive access requests from a large number of devices. Since this congestion problem causes inefficient energy consumption and increases the random access delay, an efficient random access procedure is required for various types of devices. In this paper, we propose a new access control scheme to reduce the access delay and the energy consumption by mining hidden random access resources. The proposed scheme consists of the random access procedure and the resource allocation algorithm. The proposed random access procedure utilizes the multiple access class barring (ACB) procedure to mine and utilize the hidden random access opportunities (RAOs) in order to increase the number of successfully admitted devices. The proposed algorithm optimizes the resource allocation parameters according to the estimated number of devices. We provide an analytical model for the proposed scheme by using an embedded Markov chain. The proposed scheme is shown to reduce the random access delay and the energy consumption for green communications by achieving 53 percent maximum efficiency compared to 37 percent in the conventional schemes with the ACB and random access procedure. [ABSTRACT FROM AUTHOR]

Power Beacons (PBs) can transfer energy wirelessly to devices in a wireless powered communication network. When PBs are deployed in an IEEE 802.11 Wireless LAN (WLAN), the energy transfer of PBs may interfere with the Wi-Fi stations if Wi-Fi stations and PBs share the same frequency band. In this letter, to resolve this interference problem, we propose a new Medium Access Control (MAC) protocol for IEEE 802.11 Wi-Fi stations to efficiently coexist with PBs. PBs contend just as Wi-Fi stations to gain opportunity for transferring energy and determine its operation based on the average energy level of stations. It is demonstrated that the throughput of the proposed MAC protocol is superior to that of IEEE 802.11 WLAN without interference control. [ABSTRACT FROM PUBLISHER]

Vehicular ad hoc networks (VANETs) provide information and entertainment to drivers for safe and enjoyable driving. Wireless Access in Vehicular Environments (WAVE) is designed for VANETs to provide services efficiently. Since the control messages transmitted in WAVE are broadcast, the probability of collision increases by increasing the number of vehicle nodes. In this paper, we propose a coordinated multichannel medium access control (C-MAC) protocol for VANETs. The proposed C-MAC protocol provides contention-free broadcasting for safety messages by the coordination of roadside units (RSUs). An RSU schedules the broadcasting order of transmissions for safety messages. Contention-free broadcasting lowers the probability of collision and reduces the required time for transmissions of safety messages. An RSU may play the role of harvesting energy wirelessly to coordinated VANET terminals, which are gateways for Internet-of-things devices in the car. The contention interval for service channels is optimized to provide maximum throughput. The proposed C-MAC protocol is shown to enhance throughput and delay via analysis and simulation. [ABSTRACT FROM AUTHOR]

Summary: In a wireless powered communication network (WPCN), sensor nodes harvest energy to transmit information. By a harvest‐then‐transmit (HT) protocol, nodes can be classified into either energy receiving (ER) or data transmitting (DT) nodes depending on the current level of the harvested energy. Since nodes may join or leave a network any time and energy levels vary, the distribution of ER and DT nodes changes over time. As the number of contending DT nodes is highly dynamic, a quick learning mechanism is required for an access point (AP). We propose a learning AP that learns from experience and adapts the frame size according to the changes in the number of DT nodes. The proposed learning AP is also shown to learn well and react to the situation. We compare the performances of the proposed learning mechanism with a WPCN and conventional HT FSA schemes. The proposed RL scheme outperforms the comparative schemes in terms of success rate and delay. [ABSTRACT FROM AUTHOR]