Hantao Xu

Implementation of a Project-Based Telecommunications Engineering Design Course

This paper describes and discusses the implementation of a project-based graduate design course in telecommunications engineering. This course, which requires a combination of technical and soft skills for its completion, enables guided independent learning (GIL) and application of technical knowledge acquired from classroom learning. Its main implementation challenge is the need for instructors to define graduate-level GIL activities that are unique for the project objectives and scope. This process is required at both the system and subsystem levels. These activities must also satisfy the program learning outcomes and course outcomes (PLOs and COs). The course initiation, implementation, and management are first described from the instructors perspective. Technical specifications and outcomes from a recently implemented project titled “A Human-Inspired Telecommunication System” is taken as a case study. Besides explaining the methodology used to evaluate both the course and the students, an empirical assessment of PLOs and COs against the associated educational activities is also presented. Results of a student exit survey, in which each instrument was mapped to specific COs, indicated that the intended course objectives had been accomplished and that there was a good level of student satisfaction.

An Architectural Scheme for Real-Time Multiple Users Beam Tracking Systems

In this paper, the design, building, and functioning of a complete communication system with 16 antenna elements, software-defined radio, and beam-tracking capabilities for up to four users is reported. Since the design uses components off the shelf, it is relatively low cost, which makes it feasible to be used in high-volume commercial applications. A key feature is that all digital beamforming and advanced direction-of-arrival tracking algorithms are integrated into one segment—the multiple users beam tracker. Experimental results with regard to system performance, responding time, and efficiency illustrate the effectiveness of the concept.

Simple Technique to Predict Beam Direction Based on Element Pattern and Array Factor in Small- and Medium-Sized Arrays

It is well known that, in an array, the actual beam direction differs from the beam direction of the array factor. This is an issue coming up especially when studying beam steering in small- and medium-sized arrays. There, the effect may be considerable. It seriously affects the electronics taking care of the steering. This letter derives a simple relation between the actual beam direction and the beam direction of the array factor. Its use makes the programming of electronic beam steering much easier. This relation is validated by experiments on a 2×1 array, the array most sensitive to the effect, and an 8×8 array.

Off-the-Shelf Low-Cost Target Tracking Architecture for Wireless Communications

A compact architecture for real-time directions-of-arrival estimation, tracking, and beamforming is presented. It is based on the phased-array concept. Beamforming is digitally realized. The system concept and architecture are described in full detail. A proof of concept prototype, including a 1 × 2 planar array, an analog front end, and an field programmable gate array (FPGA)-based embedded system, is built and measured. The system is controlled by a GUI running on a mainstream laptop. The architecture is tailored to the use of low cost, off the shelf, and readily available components.

Experimental Assessment of the Coarray Concept for DoA Estimation in Wireless Communications

The direction of arrival (DoA) estimation performance of three different coarray structures, namely, the nested array, the coprime sampling array, and the sparse ruler array are presented and compared. The coarray concept makes it possible to detect the DoAs of much more sources than the number of physical antennas. Crucial is that for the first time, these coarrays are investigated based on real measurements conducted on a demonstrator platform. Based on the results obtained, the conclusion is clear. The MUSIC algorithm-based coarray concept with spatial smoothing is not suitable for DoA estimation in practical circumstances due to the unavoidable multipath phenomenon.

A Dual-Band Cavity Antenna Embedded Within Multiple Metallic Enclosures

This work describes the design and evaluation of an antenna to be embedded within multiple metallic cavity like structures of quite arbitrary shape. The design is based on an open substrate-integrated waveguide (SIW) implemented with RO 4003 substrate, aiming to miniature the cavity and suited for fabrication with printed-circuit board (PCB) technology. A pair of vias is used to tune the resonances of the cavity for dual-band operation [2.45 and 5-GHz wireless local area network (WLAN) bands], and an open-loop resonator is introduced to enhance the bandwidth. The cavity antenna is fed by a stripline to avoid cross coupling with other devices. Evaluations have been performed both in freespace (FS) and inside multiple metallic cavities. Operating from within the cavities, a good antenna performance is obtained with a maximum -10-dB bandwidth of 4% at 2.45 GHz and 25% at 5.5 GHz. Simulations and measurements agree well. As a proof of concept, the proposed antenna was connected to several WLAN modules inside realistic metallic cavity environments and its operation was evaluated in a realistic indoor environment. These real-life tests confirm that the maximum data rate of 54 Mb/s is obtained for most practical situations, in which the antenna has to operate.