794 research outputs found
Limits on the Capacity of In-Band Full Duplex Communication in Uplink Cellular Networks
Simultaneous co-channel transmission and reception, denoted as in-band full
duplex (FD) communication, has been promoted as an attractive solution to
improve the spectral efficiency of cellular networks. However, in addition to
the self-interference problem, cross-mode interference (i.e., between uplink
and downlink) imposes a major obstacle for the deployment of FD communication
in cellular networks. More specifically, the downlink to uplink interference
represents the performance bottleneck for FD operation due to the uplink
limited transmission power and venerable operation when compared to the
downlink counterpart. While the positive impact of FD communication to the
downlink performance has been proved in the literature, its effect on the
uplink transmission has been neglected. This paper focuses on the effect of
downlink interference on the uplink transmission in FD cellular networks in
order to see whether FD communication is beneficial for the uplink transmission
or not, and if yes for which type of network. To quantify the expected
performance gains, we derive a closed form expression of the maximum achievable
uplink capacity in FD cellular networks. In contrast to the downlink capacity
which always improves with FD communication, our results show that the uplink
performance may improve or degrade depending on the associated network
parameters. Particularly, we show that the intensity of base stations (BSs) has
a more prominent effect on the uplink performance than their transmission
power
DbSWPT: A Novel Distance-based Switch for Efficient Wireless Power Transfer in Battery-less Wireless Capsule Endoscopy
The restricted power supply of batteries hampered the development of capsule endoscopy. Accordingly, a distance-based switch is proposed for efficient wireless power transfer (WPT) system. It targets battery-less wireless capsule endoscopy (WCE). The proposed system consists of two separate coils with distance significant impact. To tackle problem, a distance-based switch configuration is proposed between two variable load resistances according to distance between transmitting and receiving circuits. Results proved high efficiency at short distances using potentiometer in decreasing direction which starts with high resistance values and then decreases to a certain value of resistance according to measured distance whereas the other has a high efficiency at long distances using potentiometer in increasing direction which starts with low resistance values and then increases to certain value of resistance according to measured distance. The results illustrated that the system performance using series-series (S-S) configuration is superior to using the parallel-parallel (P-P) configuration. It is found that the minimum efficiency for the proposed P-P distance-based switch is 51%, while for the proposed P-S is 83.33% . Accordingly, the proposed switch-based S-S configuration achieved minimum efficiency 90.91%. It increases the efficiency by 8.34%
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