Radio Resource Allocation for Device-to-Device Underlay Communication Using Hypergraph Theory

Device-to-Device (D2D) communication has been recognized as a promising technique to offload the traffic for the evolved Node B (eNB). However, the D2D transmission as an underlay causes severe interference to both the cellular and other D2D links, which imposes a great technical challenge to radio resource allocation. Conventional graph based resource allocation methods typically consider the interference between two user equipments (UEs), but they cannot model the interference from multiple UEs to completely characterize the interference. In this paper, we study channel allocation using hypergraph theory to coordinate the interference between D2D pairs and cellular UEs, where an arbitrary number of D2D pairs are allowed to share the uplink channels with the cellular UEs. Hypergraph coloring is used to model the cumulative interference from multiple D2D pairs, and thus, eliminate the mutual interference. Simulation results show that the system capacity is significantly improved using the proposed hypergraph method in comparison to the conventional graph based one.Comment: 27 pages,10 figure

A dual-grating InGaAsP/InP DFB laser integrated with an SOA for THz generation

We report a dual-mode semiconductor laser that has two gratings with different periods below and above the active layer. A semiconductor optical amplifier (SOA), which is integrated with the dual-mode laser, plays an important role in balancing the optical power and reducing the linewidths of the emission modes. A stable two mode emission with the 13.92-nm spacing can be obtained over a wide range of distributed feedback and SOA injection currents. Compared with other types of dual-mode lasers, our device has the advantages of simple structure, compact size, and low fabrication cost

Analysis of diesel engine isolation system with piston slap

An isolation system of diesel engine with cylinder gap was modeled to deeply study the effect of piston shock on the whole vibration system. With the diesel engine rotates at rated speed, the center of engine body mass moves in plane with an obvious ellipse, and the magnitude is enlarged high to 3.5 times of the origin. All the bottom three directional springs have the corresponding response with the fundamental frequency signal, and a characteristic frequency band, as the piston slap is considered