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This paper presents an ultra-wideband(UWB) microstrip patch antenna with a simple pentagonal geometry and two notches. The UWB characteristics is achieved by using defective ground and impedance conversion methods, yielding a frequency band coverage from 3.1 GHz to 10.6 GHz where the voltage standing wave ratio(VSWR) is no more than 2. A rectangular slit and a narrow U-shape slot are etched in on the patch and feed-line respectively to achieve notch performance at WLAN band(5.15 GHz~5.85 GHz) and X-band communication downlink band(7.25 GHz~7.7 GHz). The antenna presents good radiation characteristics in its operational UWB, and measured results are in good agreements with the simulation, which accordingly validates the design.

Sparse code multiple access(SCMA) is a novel non-orthogonal multiple access scheme to face the future 5G communication. In allusion to the problem that sparse code multiple access(SCMA) system based on a logarithm-domain MAX-Log message passing algorithm(MPA) for multiuser detection has lower detection performance, this paper adopts a method that the message updating formula of the resource node is multiplied by a factor, which can reduce the lost messages of the original MAX-Log MPA algorithm for approximate computing the updating message of resource node. The theory and simulation results show that the improved MAX-Log MPA multiuser detection algorithm can not only maintain the low complexity of the original MAX-Log MPA algorithm, but also obtains better detection performance.

To solve the problem of limited capacity and high detection complexity for generalized frequency division multiplexing (GFDM) used by the fifth generation (5G) mobile communication system candidate multicarrier modulation technology, the GFDM is combined with spatial modulation MIMO to build system A scheme for optimal antenna combination and modified signal detection was proposed, the capacity of modified system was analyzed, and the computational complexity and error rate of the system were compared, which was used by the modified multiple stage (MMS) detection algorithm and other detection algorithms. The simulation results show that the system with antenna selection optimization has larger ergodic channel capacity in different antenna equipments, resulting in lower computational complexity and better symbol error rate performance when using the modified multiple stage detection. [ABSTRACT FROM AUTHOR]