Jialiang Zhang’s research while affiliated with University of Wisconsin–Madison and other places

The 60 GHz wireless technology holds great potential for multi-Gbps communications and high-precision radio sensing. But the lack of an accessible experimental platform has been impeding its progress. We propose to overcome the barrier with OpenMili, a reconfigurable 60 GHz radio architecture. OpenMili builds from off-the-shelf FPGA processor, data converters and 60 GHz RF front-end. It employs customized clocking, channelization and interfacing modules, to achieve Gsps sampling bandwidth, Gbps wireless bit-rate, and Gsps sample streaming from/to a PC host. It also incorporates the first programmable, electronically steerable 60 GHz phased-array antenna. OpenMili adopts programming models that ease development, through automatic parallelization inside signal processing blocks, and modular, rate-insensitive interfaces across blocks. In this demo, we will showcase OpenMili's hardware modules, and demonstrate example communication and sensing applications based on it.

The 60 GHz wireless technology holds great potential for multi-Gbps communications and high-precision radio sensing. But the lack of an accessible experimental platform has been impeding its progress. In this paper, we overcome the barrier with OpenMili, a reconfigurable 60 GHz radio architecture. OpenMili builds from off-the-shelf FPGA processor, data converters and 60 GHz RF front-end. It employs customized clocking, channelization and interfacing modules, to achieve Gsps sampling bandwidth, Gbps wireless bit-rate, and Gsps sample streaming from/to a PC host. It also incorporates the first programmable, electronically steerable 60 GHz phased-array antenna. OpenMili adopts programming models that ease development, through automatic parallelization inside signal processing blocks, and modular, rate-insensitive interfaces across blocks. It provides common reference designs to bootstrap the development of new network protocols and sensing applications. We verify the effectiveness of OpenMili through benchmark communication/sensing experiments, and showcase its usage by prototyping a pairwise phased-array localization scheme, and a learning-assisted real-time beam adaptation protocol.

Visible light communication (VLC) technology piggybacks on legacy illumination infrastructure, and creates a communication channel by modulating LEDs' light emission patterns. Existing VLC research mostly focused on improving single link communication capacity, or localizing a single static handset equipped with light sensors. In this paper, we advance this technology to the next layer, and propose an integrated visible light network (VLN) architecture that aims to realize continuous communication coverage and location tracking for indoor mobile devices. Our VLN architecture uses a powerline backbone together with a backend server to centrally control and coordinate ceiling-mounted LED access points (APs). The LED APs are dynamically clustered depending on the client location, and tightly synchronize and cooperate with each other, in order to enhance link quality and spatial diversity, thus smoothing the client's transition between cells and alleviating the impact of device motion, body shadowing, etc.. We have proto-typed the VLN architecture using customized hardware platform and an entire software-defined network stack. Preliminary results demonstrate the feasibility of the VLN concept, and potential of the architectural design.

Mobile devices are shrinking their form factors for portability, but user-mobile interaction is becoming increasingly challenging. In this paper, we propose a novel system called Okuli to meet this challenge. Okuli is a compact, low-cost system that can augment a mobile device and extend its interaction workspace to any nearby surface area. Okuli piggybacks on visible light communication modules, and uses a low-power LED and two light sensors to locate user's finger within the workspace. It is built on a light propagation/reflection model that achieves around one-centimeter location precision, with zero run-time training overhead. We have prototyped Okuli as an Android peripheral, with a 3D-printed shroud to host the LED and light sensors. Our experiments demonstrate Okuli's accuracy, stability, energy efficiency, as well as its potential in serving virtual keyboard and trackpad applications.

Device-to-device(D2D) underlaying communication brings great benefits to the cellular networks from the improvement of coverage and spectral efficiency at the expense of complicated transceiver design. With frequency spectrum sharing mode, the D2D user generates interference to the existing cellular networks either in downlink or uplink. Thus the resource allocation for D2D pairs should be designed properly in order to reduce possible interference, in particular for uplink. In this paper, we introduce a novel bandwidth allocation scheme to maximize the utilities of both D2D users and cellular users. Since the allocation problem is strongly NP-hard, we apply a relaxation to the association indicators. We propose a low-complexity distributed algorithm and prove the convergence in a static environment. The numerical result shows that the proposed scheme can significant improve the performance in terms of utilities.The performance of D2D communications depends on D2D user locations, the number of D2D users and QoS(Quality of Service) parameters.