Exploiting Capture Diversity for Performance Enhancement of ALOHA-Based Multi-Static Backscattering Systems in the 6G Perspective

In this paper, we consider the emerging context of ALOHA-based multi-static backscattering communication systems. By assuming an architecture consisting of a set of passive backscattering nodes, an illuminator, and a set of spatially dislocated receivers, we firstly propose a cross-layer framework for performance analysis. The model jointly accounts for the shared wireless channel, including fading and capture effect, and channel contention strategy, which is regulated by a Framed Slotted ALOHA protocol. Furthermore, based on the inherent macroscopic diversity offered by the multi-static settings, we introduce the concept of capture diversity, which is shown to enable multiple packet detection in slots with multiple transmissions. In order to characterize the multiple access interference and approximate the capture probabilities, we enforce a log-normal approximation of the inverse Signal-to-Interference Ratio that relies on moment matching. Numerical results show the impact of deployment scenarios and the relative positions of illuminator, backscattering nodes, and receivers on the system normalized throughput. We show how the number of detection points impacts the system performance under various channel conditions. Moreover, the accuracy of the proposed approximation rationale is validated via Monte Carlo simulations. Finally, we analyze the optimal frame length in the presence of capture diversity.

The Integration Of IEEE 802.11 (WLAN) With RFID Systems in ISM (2.45 GHz) Frequency Band Environment Using Framed Slotted ALOHA And IEEE 802.15.4

In this thesis, we attempt to solve the problem of WLAN/RFID coexistence and integration in frequency band of GHz or ISM band. Our solution to this problem is to allow the WLAN access and RFID access in a time-sharing manner by making the WLAN Access Point aware of the RFID neighbor-network at MAC layer. The time-sharing function is implemented using IEEE 802.11 PCF mechanism. RFID network is implemented using two different standards. The first one is Framed Slotted Aloha standard and the second one is IEEE 802.15.4 standard. We have simulated both models using Artifex simulator and compared their performance using some performance metrics like collision probability and average number of collision in each superframe. It is shown that IEEE 802.15.4 based model outperforms the Framed Slotted Aloha based model.

The Integration Of IEEE 802.11 (WLAN) With RFID Systems in ISM (2.45 GHz) Frequency Band Environment Using Framed Slotted ALOHA And IEEE 802.15.4

In this thesis, we attempt to solve the problem of WLAN/RFID coexistence and integration in frequency band of GHz or ISM band. Our solution to this problem is to allow the WLAN access and RFID access in a time-sharing manner by making the WLAN Access Point aware of the RFID neighbor-network at MAC layer. The time-sharing function is implemented using IEEE 802.11 PCF mechanism. RFID network is implemented using two different standards. The first one is Framed Slotted Aloha standard and the second one is IEEE 802.15.4 standard. We have simulated both models using Artifex simulator and compared their performance using some performance metrics like collision probability and average number of collision in each superframe. It is shown that IEEE 802.15.4 based model outperforms the Framed Slotted Aloha based model.

A Framed Slotted ALOHA-Based MAC for Eliminating Vain Wireless Power Transfer in Wireless Powered IoT Networks

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.