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

In-Band Full-Duplex Communications for Cellular Networks with Partial Uplink/Downlink Overlap

In-band full-duplex (FD) communications have been optimistically promoted to improve the spectrum utilization in cellular networks. However, the explicit impact of spatial interference, imposed by FD communications, on uplink and downlink transmissions has been overlooked in the literature. This paper presents an extensive study of the explicit effect of FD communications on the uplink and downlink performances. For the sake of rigorous analysis, we develop a tractable framework based on stochastic geometry toolset. The developed model accounts for uplink truncated channel inversion power control in FD cellular networks. The study shows that FD communications improve the downlink throughput at the expense of significant degradation in the uplink throughput. Therefore, we propose a novel fine-grained duplexing scheme, denoted as $\alpha$-duplex scheme, which allows a partial overlap between uplink and downlink frequency bands. To this end, we show that the amount of the overlap can be optimized via adjusting $\alpha$ to achieve a certain design objective.Comment: To be presented in IEEE Globecom 201

Geotechnical Behavior of Stabilized Dunes Sand by Cement

The dunes sand is wide spread with huge quantities all over the world especially in desert areas near roads. The objective of the current paper is to use dunes sand as a foundation soil under structures instead of utilizing expensive replacement with structural fills. The dunes sand samples were collected from a site outside Tabuk city in the north-west of Saudi Arabia. Several experimental tests were performed on the dunes sand samples such as sieve analysis, standard Proctor compaction, drained direct shear and CBR. The test results indicated that the sand dunes are SP according to USCS. The sand dunes have also low shear strength and CBR value. The bearing ability of the sand dunes became weaker due to water immersion. Therefore, the construction on the non-treated dunes sand is impossible. For the later reason, the dunes sand was stabilized with various ordinary Portland cement fractions ranging from 3% to 15%. Compaction and CBR tests were conducted on the stabilized dunes sand. The maximum dry density increased as the increments of the cement contents accompanying with the decrement of porosity and optimum moisture content. The stabilized dunes sand implied higher CBR values than the non-treated soil.  The CBR values of the stabilized soil increased with increasing cement fractions. The stabilized dunes sand induced very high CBR values after longer curing times for all the utilized cement contents. The stabilized dunes sand using only 3% is considered the optimum design achieving good performance under structures and best economic mix