Xiaojun Yuan

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—In this paper, we endeavour to seek a fundamental understanding of the potentials and limitations of training-based multiuser multiple-input multiple-output (MIMO) systems. In a multiuser MIMO system, users are geographically separated. So, the near-far effect plays an indispensable role in channel fading. The existing optimal training design for(More)
In Cloud Radio Access Network (C-RAN), the high computational complexity of signal processing becomes unaffordable due to the large number of RRHs and users. This paper endeavours to use message passing to design a scalable uplink signal detection algorithm, in the sense that the complexity grows linear with the network size. However, message passing cannot(More)
A Content, Context, Connection and Researching, Reasoning, Reflecting (3C3R) model is a conceptual framework for problem-based learning (PBL) problem design. We introduced the 3C3R-PBL method into a pediatric teaching plan, and evaluated its effectiveness and feasibility. The 3C3R model was applied in a pediatric problem design teaching plan "why the lips(More)
—We consider training-based channel estimation for a cloud radio access network (CRAN), in which a large amount of remote radio heads (RRHs) and users are randomly scattered over the service area. In this model, assigning orthogonal training sequences to all users will incur a substantial overhead to the overall network, and is even impossible when the(More)
—This letter studies the optimal degrees of freedom (DoF) region for the asymmetric MIMO Y channel, where each user i (i = 1, 2, 3), equipped with Mi antennas, can exchange independent messages with the other two users via the help of a common relay, equipped with N antennas. To deal with the asymmetric data exchange pattern within each user pair, we(More)
Cloud Radio Access Network (C-RAN) is a promising architecture for unprecedented capacity enhancement in next-generation wireless networks thanks to the centralization and virtualization of base station processing. However, centralized signal processing in C-RANs involves high computational complexity that quickly becomes unaffordable when the network grows(More)
In this paper, we study the degrees of freedom (DoF) of a new network information flow model called symmetric multi-relay MIMO Y channel, where three user nodes, each with M antennas, communicate via K geographically separated relay nodes, each with N antennas. For this model, we establish a general DoF achievability framework based on linear precoding and(More)
Conventionally, secrecy is achieved using cryptographic techniques beyond the physical layer. Recent studies raise the interest of performing encryption within the physical layer by exploiting some unique features of the physical wireless channel. Following this spirit, we present a novel physical layer encryption (PLE) scheme that randomizes the radio(More)
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