Experimental demonstration of a 35 GHz holographic antenna
We have developed a novel two-dimensional grating antenna based on microwave holography. The two-dimensional grating (hologram) is formed on a dielectric substrate and fed by an integrated surface wave exciter. Various design issues will be presented, as will a 35 GHz demonstration prototype antenna designed, fabricated, and tested. Measured radiation patterns closely agreed with the theoretical prediction.
Volume-type holographic antenna
A new type of holographic antenna based on the principle of the volume hologram is proposed. The characteristics of the prototype are examined. The antenna has a unidirectional beam with a front-to-back ratio of 20 dB. The practical frequency handwidth is about 10 percent of the center frequency. The antenna is unique in that the feed point is placed in the plane of the holographic plate so that both feeder and the holographic plate could be made out of one printed circuit board for easy flush mount installation or mass production, although the feeder of the prototype antenna was a pyramidal horn.
A traffic scheduling framework in broadband wireless access systems
In this paper, we present a traffic scheduling framework for allocating the upstream channel bandwidth in broadband wireless access systems, where both voice and data applications are supported. Our traffic scheduling framework is aimed at supporting diverse QoS requirements and obtaining high utilization of the upstream bandwidth. It prioritizes traffic streams according to different classes of service, and provides fair access of bandwidth to the users. The presented framework consists of three algorithms: a calibration algorithm for the jittered constant bit rate (CBR) traffic, a scheduling algorithm for the jittered CBR traffic, and a scheduling algorithm for the unspecified bit rate traffic. The proposed algorithms are feasible when either the asynchronous transfer mode or multi-protocol label switching protocol is deployed at the network edge. Simulation results are presented to demonstrate the effectiveness of our algorithms in achieving high bandwidth utilization and the good traffic performance in terms of both cell loss ratio and mean queuing delay.