An Adaptive Soft Handover Scheme Using Fuzzy Load Balancing for WCDMA Systems

In cellular systems, user distribution variations can cause load imbalance between cells. Embedding a load balancing strategy within the handover scheme means that ensuing traffic congestion can be alleviated by dynamically reallocating load between neighbouring cells. An adaptive soft handover scheme for multimedia cellular communication systems is proposed in this paper, that considers both the cell load factors as well as the pilot channel signal-to-interference-and-noise-ratio (SINR) for soft handovers. By using fuzzy principles, the soft handover thresholds and time hysteresis are adapted dependent upon the loads of the neighbouring cells. Simulation results show that the new algorithm provides improved system performance in terms of a more evenly distributed load, lower blocking probabilities and higher throughput

Using SINR as Vertical Handoff Criteria in Multimedia Wireless Networks

In the next generation multimedia wireless network environment that consists of heterogeneous access technologies, we need to offer the end user with multimedia QoS inside each access network as well as during vertical handoff between them. The vertical handoff algorithm have to be QoS aware, which cannot be achieved by using the traditional RSS as the vertical handoff criteria. In this paper, we propose a new vertical handoff algorithm using the receiving SINR from various access networks as the handoff criteria. By converting the different receiving SINR values, the handoff algorithm can have the knowledge of achievable bandwidths from both access networks, and make handoff decisions with multimedia QoS consideration. Analysis results confirms that the new SINR based vertical handoff algorithm is able to consistently offer the end user with maximum available bandwidth during vertical handoff comparing with the RSS based vertical handoff, whose performance differs under different network conditions

Combined SINR Based Vertical Handoff Algorithm for Next Generation Heterogeneous Wireless Networks

Next generation heterogeneous wireless networks offer the end users with assurance of QoS inside each access network as well as during vertical handoff between them. For guaranteed QoS, the vertical handoff algorithm must be QoS aware, which cannot be achieved with the use of traditional RSS as the vertical handoff criteria. In this paper, we propose a novel vertical handoff algorithm which uses received SINR from various access networks as the handoff criteria. This algorithm consider the combined effects of SINR from different access networks with SINR value from one network being converted to equivalent SINR value to the target network, so the handoff algorithm can have the knowledge of achievable bandwidths from both access networks to make handoff decisions with QoS consideration. Analytical results confirm that the new SINR based vertical handoff algorithm can consistently offer the end user with maximum available bandwidth during vertical handoff contrary to the RSS based vertical handoff, whose performance differs under different network conditions. System level simulations also reveal the improvement of overall system throughputs using SINR based vertical handoff, comparing with the RSS based vertical handoff

Comparison of the effects of rumen-protected and unprotected L-leucine on fermentation parameters, bacterial composition, and amino acids metabolism in in vitro rumen batch cultures

This study was conducted to compare the effects of rumen-protected (RP-Leu) and unprotected L-leucine (RU-Leu) on the fermentation parameters, bacterial composition, and amino acid metabolism in vitro rumen batch incubation. The 5.00 g RP-Leu or RU-Leu products were incubated in situ in the rumen of four beef cattle (Bos taurus) and removed after 0, 2, 4, 6, 12, 16, and 24 h to determine the rumen protection rate. In in vitro incubation, both RP-Leu and RU-Leu were supplemented 1.5 mmol/bottle (L-leucine HCl), and incubated after 0, 2, 4, 6, 8, 12, and 16 h to measure gas production (GP), nutrient degradability, fermentation parameters, bacterial composition, and amino acids metabolism. Results from both in vitro and in situ experiments confirmed that the rumen protection rate was greater (p < 0.01) in RP-Leu than in RU-Leu, whereas the latter was slow (p < 0.05) degraded within incubation 8 h. Free leucine from RP-Leu and RU-Leu reached a peak at incubation 6 h (p < 0.01). RU-Leu supplementation increased (p < 0.05) gas production, microbial crude protein, branched-chain AAs, propionate and branched-chain VFAs concentrations, and Shannon and Sobs index in comparison to the control and RP-Leu supplementation. RU-Leu and RP-Leu supplementation decreased (p < 0.05) the relative abundance of Bacteroidota, which Firmicutes increased (p < 0.05). Correlation analysis indicated that there are 5 bacteria at the genus level that may be positively correlated with MCP and propionate (p < 0.05). Based on the result, we found that RP-Leu was more stable than RU-Leu in rumen fluid, but RU-Leu also does not exhibit rapid degradation by ruminal microbes for a short time. The RU-Leu was more beneficial in terms of regulating rumen fermentation pattern, microbial crude protein synthesis, and branched-chain VFAs production than RP-Leu in vitro rumen conditions

A Fuzzy Adaptive Soft Handover Scheme Supporting Four Active Sets

Load imbalance between cells caused by random user distribution is a common issue in cellular systems, which often leads to traffic congestion. This can be alleviated by embedding a load balancing strategy into the handover scheme to dynamically reallocate load between neighbouring cells. A fuzzy adaptive soft handover scheme that can support four active set size is presented in this paper. In this paper, three fuzzy systems for radio link: addition, removal and replacement events are used and tuned to adapt to the soft handover thresholds and time hysteresis efficiently, depending upon the loads of the cells in user's active set. Simulation results show that the new fuzzy algorithm alleviates congestion and provides improved system performance in terms of both lower blocking probabilities and higher system capacity

Multi-dimensional adaptive SINR based vertical handoff for heterogeneous wireless networks

Vertical handoff in next generation heterogeneous wireless networks is a multi-dimensional issue. In this article we propose a multi-dimensional adaptive SINR based vertical handoff algorithm (MASVH) which uses the combined effects of SINR, user required bandwidth, user traffic cost and utilization from participating access networks to make handoff decisions for multi-attribute QoS consideration. Simulation results confirm that the new MASVH algorithm improves the system performance in terms of higher throughput and lower dropping probability, as well as reduces the user traffic cost for accessing the integrated wireless networks

Context aware vertical soft handoff algorithm for heterogeneous wireless networks

Soft handoff in WCDMA systems allows multi connection between the user and base stations during handoff, in contrast to single connection in hard handoff. But multi connection flexibility leads to a trade-off between quality of service for the user and the system downlink capacity. The heterogeneous wireless networks consist of WCDMA and WLAN systems, which operate at different frequency with no direct interference. Therefore, a vertical soft handoff between downlink shared channels from WCDMA and WLAN will not suffer similar side effects as the horizontal soft handoff in WCDMA systems. In this paper, we present an analytical framework for vertical soft handoff and propose a context-aware vertical soft handoff algorithm (CAVSH) for heterogeneous wireless networks. CAVSH considers four user and system context parameters such as user required bandwidth, user traffic cost, access network utilization, and signal to interference-and-noise ratio (SINR). The results show that the proposed CAVSH can provide the system with lower dropping probability, lower average cost to the user and higher throughput, as compared with vertical hard handoff

Breakdown Characteristics of Ga₂O₃-on-SiC Metal-Oxide-Semiconductor Field-Effect Transistors

Ultra-wide bandgap semiconductor gallium oxide (Ga2O3) features a breakdown strength of 8 MV/cm and bulk mobility of up to 300 cm2V−1s−1, which is considered a promising candidate for next-generation power devices. However, its low thermal conductivity is reckoned to be a severe issue in the thermal management of high-power devices. The epitaxial integration of gallium oxide thin films on silicon carbide (SiC) substrates is a possible solution for tackling the cooling problems, yet premature breakdown at the Ga2O3/SiC interface would be introduced due to the relatively low breakdown strength of SiC (3.2 MV/cm). In this paper, the on-state properties as well as the breakdown characteristics of the Ga2O3-on-SiC metal-oxide-semiconductor field-effect transistor (MOSFET) were investigated by using the technology computer-aided design (TCAD) approach. Compared with the full-Ga2O3 MOSFET, the lattice temperature of the Ga2O3-on-SiC MOSFET was decreased by nearly 100 °C thanks to the high thermal conductivity of SiC. However, a breakdown voltage degradation of >40% was found in an unoptimized Ga2O3-on-SiC MOSFET. Furthermore, by optimizing the device structure, the breakdown voltage degradation of the Ga2O3-on-SiC MOSFET is significantly relieved. As a result, this work demonstrates the existence of premature breakdown in the Ga2O3-on-SiC MOSFET and provides feasible approaches to further enhance the performance of hetero-integrated Ga2O3 power devices