Radio channel reservation is used to alleviate call dropping which may occur in two situations: (i) hand-off between cells in cellular networks, and (ii) channel withdrawal in wireless networks with spectrum leasing. In this article, we study a radio resource reservation scheme for heterogeneous traffic in a cellular network with spectrum leasing, in which one reservation pool is used to alleviate the two types of call droppings. Since different types of traffic have different tolerances to the exhaustion of channels, it is critical for different types of traffic to select the optimal size of the reservation pool such that the channel requirements of different types of traffic are satisfied while throughput is maximized. A three-dimensional Markov chain is presented to find the optimal size of reservation pool. Numerical and simulation results show that (i) the selected parameters of reservation satisfy the quality-of-service requirements of different types of traffic while produce high throughput, and (ii) channel withdrawal yields higher impact on real-time traffic than non-real-time traffic in terms of throughput.
Multiple access control (MAC) is crucial for devices to send data packets and harvest wireless energy in wireless powered Internet of Things (IoT) networks. A framed slotted ALOHA (FSA) protocol is employed in several practical networks. This paper studies an FSA-based MAC in a centralized wireless powered IoT network, including half-duplex devices and a full-duplex base station transmitting wireless energy in an intended direction. Under such a network, it is possible that a half-duplex device contends for a time slot to transmit a packet while the base station transmits wireless energy to the device in the same time slot, which causes vain charging and wastes the opportunity to charge other devices. To eliminate the vain charging, this paper designs a MAC in which a base station utilizes the information conveyed from devices in advance to arrange the charging order of devices. The novelty is to develop an algorithm to find a charging order of half-duplex devices instead of using full-duplex devices to eliminate the vain charging. Event-driven simulations are conducted to study the performance of the proposed MAC. Simulation results show that the proposed MAC produces better system performances than the system not eliminating the vain charging. In summary, the application of the proposed MAC yields the benefits of higher throughput and lower packet loss.
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