Jun Fan

Bio: Jun Fan is an academic researcher from Missouri University of Science and Technology. The author has contributed to research in topics: Equivalent circuit & Printed circuit board. The author has an hindex of 36, co-authored 482 publications receiving 5641 citations. Previous affiliations of Jun Fan include Ulsan National Institute of Science and Technology & University of Missouri.

Scalable and Efficient Diagnosis for 5G Data Center Network Traffic

Abstract: Data center networks (DCNs) for 5G are expected to support a large number of different bandwidth-hungry applications with exploding data, such as real-time search and data analysis. As a result, significant challenges are imposed to identify the cause of link congestion between any pair of switch ports that may severely damage the overall network performance. Generally, it is expected that the granularity of the flow monitoring to diagnose network congestion in 5G DCNs needs to be down to the flow level on a physical port of a switch in real time with high-estimation accuracy, low-computational complexity, and good scalability. In this paper, motivated by a comprehensive study of a real DCN trace, we propose two sketch-based algorithms, called α-conservative update (CU) and P(d)-CU, based on the existing CU approach. α-CU adds no extra implementation cost to the traditional CU, but successfully trades off the achieved error with time complexity. P(d)-CU fully considers the amount of skew for different types of network services to aggregate traffic statistics of each type of network traffic at an individual, horizontally partitioned sketch. We also introduce a way to produce the real-time moving average of the reported results. By theoretical analysis and sufficient experimental results on a real DCN trace, we extensively evaluate the proposed and existing algorithms on their error performance, recall, space cost, and time complexity.

PAM4 signaling considerations for high-speed serial links

Abstract: The paper discusses current challenges and advantages of multi-level signaling for high-speed serial links, showing the differences and similarities in link-path analysis between binary and multi-level signaling. Comparison of two signaling methodologies is given from the general theory viewpoint, as well as on the basis of various tests regarding crosstalk, jitter, equalizations and different channel characteristics, such as material, impedance and overall manufacturing design sensitivity.

Differential Crosstalk Mitigation in the Pin Field Area of SerDes Channel With Trace Routing Guidance

Abstract: Crosstalk noise on the printed circuit board is usually decreased by adding shielding ground (GND). In the trace routing area, the shielding vias are added to isolate the coupling between different traces. In the ball gate array (BGA) and pin field area, assigning more GND pins has demonstrated the effectiveness of crosstalk reduction between signals. However, such design decreases the signal to ground (S:G) ratio dramatically, herein, it is not suitable for applications that require high signal pin density. Unlike the treatment in the conventional methodology, in this paper, the differential crosstalk is mitigated by using the principle of symmetry on two adjacent differential signal pairs in the BGA and pin field regions. New full pin map patterns are proposed and compared with the conventional full pin map patterns. Without sacrificing the S:G ratio, the proposed maps prove the superiority in mitigating both differential far-end and near-end integrated crosstalk noise. To maintain the low crosstalk level in the entire link path, guidance of differential trace routing is provided and demonstrated in the details. All models in this paper satisfy SerDes channel designing and manufacturing requirements.

A circuit approach to model narrow slot structures in a power bus

Abstract: A coupled transmission line model for narrow slot structures in DC power planes is proposed. This approach, combined with SPICE-based cavity models and a segmentation method, provides an easy and fast way to model relatively complex structures of power planes with narrow slots often used for isolation purposes. This approach is used to achieve isolation using gapping. The cavity model formulations for rectangular and isosceles right triangular segments are reviewed. The rationale of modeling the narrow slot as a three-conductor transmission line is described. The modeling results are shown and compared with the output of a full wave simulation tool, HFSS, and with experimental measurements.

Evaluating Field Interactions Between Multiple Wires and the Nearby Surface Enabled by a Generalized MTL Approach

Abstract: Interactions between a cable harness containing multiple wires and the nearby metal surface can be evaluated by full-wave methods. Though these methods can calculate the interactions with great accuracy, they have long simulation times and large memory requirements when dealing with complex wire structures. The multiple scattering (MS) approach by treating the cable harness and the surface separately using different algorithms has been proven to be superior to the full-wave methods when evaluating these interactions. However, the cable harness solver in the previous MS approach is restricted to two-wire structures since the per-unit-length (pul) inductance ( L ) and capacitance ( C ) are derived based on the antenna and differential modes assumption between two wires. In this paper, a generalized multiconductor transmission-line (GMTL) approach is proposed to overcome the two-wire limitation. In the GMTL approach, all wires take the infinity as the reference. The extraction of the pul L and C for the cable harness is not limited by the number of wires. Thus, the GMTL approach can conveniently model multiple wire structures. The application of the GMTL approach to the multiple wires enables the MS approach to accurately evaluate the interactions between the cable harness and the metal surface.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

IEEE Transactions on Microwave Theory and Techniques and Antennas and Propagation Announce a Joint Special Issue on Ultra-Wideband (UWB) Technology

Abstract: Before the emergence of ultra-wideband (UWB) radios, widely used wireless communications were based on sinusoidal carriers, and impulse technologies were employed only in specific applications (e.g. radar). In 2002, the Federal Communication Commission (FCC) allowed unlicensed operation between 3.1–10.6 GHz for UWB communication, using a wideband signal format with a low EIRP level (−41.3dBm/MHz). UWB communication systems then emerged as an alternative to narrowband systems and significant effort in this area has been invested at the regulatory, commercial, and research levels.