Advanced Quantizer Designs for FDD-Based FD-MIMO Systems Using Uniform Planar Arrays

Massive multiple-input multiple-output (MIMO) systems, which utilize a large number of antennas at the base station, are expected to enhance network throughput by enabling improved multiuser MIMO techniques. To deploy many antennas in reasonable form factors, base stations are expected to employ antenna arrays in both horizontal and vertical dimensions, which is known as full-dimension (FD) MIMO. The most popular two-dimensional array is the uniform planar array (UPA), where antennas are placed in a grid pattern. To exploit the full benefit of massive MIMO in frequency division duplexing (FDD), the downlink channel state information (CSI) should be estimated, quantized, and fed back from the receiver to the transmitter. However, it is difficult to accurately quantize the channel in a computationally efficient manner due to the high dimensionality of the massive MIMO channel. In this paper, we develop both narrowband and wideband CSI quantizers for FD-MIMO taking the properties of realistic channels and the UPA into consideration. To improve quantization quality, we focus on not only quantizing dominant radio paths in the channel, but also combining the quantized beams. We also develop a hierarchical beam search approach, which scans both vertical and horizontal domains jointly with moderate computational complexity. Numerical simulations verify that the performance of the proposed quantizers is better than that of previous CSI quantization techniques.Comment: 15 pages, 6 figure

Sport Labor Migration and Collegiate Sport in the United States: A Typology of Migrant Athletes

The global migration of athletes has been increasing in a variety of sporting contexts around the globe. Notably, the past decade has seen a nearly threefold increase in the number of international athletes coming to the United States for the purposes of participating in collegiate sport. In accordance with such growing internationalization, a body of research in the area of sport labor migration has developed. The purposes of the current study were to improve our understanding of the forces that lead athletes to the U.S. in order to participate in collegiate sport and to explicitly connect research on international collegiate athletes to the broader context of sport labor migration research. In doing so, we utilized the typologies of migrant athletes developed by Maguire (1999) and Magee and Sugden (2002) as a conceptual framework for analysis. Based on findings from qualitative interviews with international collegiate athletes, we present a revised typology including the categories of mercenary, nomadic cosmopolitan, settler, returnee, exile, and ambitionist to help understand the diversity of factors and experiences associated with the migration of athletes in the context of U.S. collegiate sport

Robust Non-Linear Feedback Coding via Power-Constrained Deep Learning

The design of codes for feedback-enabled communications has been a long-standing open problem. Recent research on non-linear, deep learning-based coding schemes have demonstrated significant improvements in communication reliability over linear codes, but are still vulnerable to the presence of forward and feedback noise over the channel. In this paper, we develop a new family of non-linear feedback codes that greatly enhance robustness to channel noise. Our autoencoder-based architecture is designed to learn codes based on consecutive blocks of bits, which obtains de-noising advantages over bit-by-bit processing to help overcome the physical separation between the encoder and decoder over a noisy channel. Moreover, we develop a power control layer at the encoder to explicitly incorporate hardware constraints into the learning optimization, and prove that the resulting average power constraint is satisfied asymptotically. Numerical experiments demonstrate that our scheme outperforms state-of-the-art feedback codes by wide margins over practical forward and feedback noise regimes, and provide information-theoretic insights on the behavior of our non-linear codes. Moreover, we observe that, in a long blocklength regime, canonical error correction codes are still preferable to feedback codes when the feedback noise becomes high.Comment: To appear in International Conference on Machine Learning (ICML) 202

Coverage of the Gay Games from 1980-2012 in U.S. Newspapers: An Analysis of Newspaper Article Framing

Many members of the LGBT community have viewed the Gay Games as an opportunity to challenge dominant ideologies concerning sexuality and sport participation. Members of the mass media, however, play a potentially important role in how the event is perceived by the general public. Therefore, the primary purpose of the current study was to examine how the Gay Games have been framed in newspaper coverage. A total of 646 articles published in the United States covering the eight Gay Games events held during the 32-year period of 1980–2012 were analyzed in terms of three aspects of framing: (a) the types of issues highlighted, (b) the sources of information cited, and (c) the manner in which either episodic or thematic narratives were employed. The results of the current study revealed that issues of identity and optimism were most commonly highlighted, LGBT participants were most frequently cited as sources of information, and thematic framing was most commonly employed in newspaper coverage of the Gay Games