Lattices from Codes for Harnessing Interference: An Overview and Generalizations

In this paper, using compute-and-forward as an example, we provide an overview of constructions of lattices from codes that possess the right algebraic structures for harnessing interference. This includes Construction A, Construction D, and Construction $\pi_A$ (previously called product construction) recently proposed by the authors. We then discuss two generalizations where the first one is a general construction of lattices named Construction $\pi_D$ subsuming the above three constructions as special cases and the second one is to go beyond principal ideal domains and build lattices over algebraic integers

VIRTUAL TOURISM: IDENTIFYING THE FACTORS THAT AFFECT A TOURIST\u27S EXPERIENCE AND BEHAVIORAL INTENTIONS IN A 3D VIRTUAL WORLD

Given the increase in the use of technologies within the tourism industry, particularly the rising interest in virtual worlds such as Second Life, the purpose of this study is to identify the factors related to the 3D virtual tourism experience and behavioral intentions after visiting a virtual tourism destination. Two theories, the Technology Acceptance Model and Self-Determination Theory, were used to guide this study, both of which were found to be useful frameworks. Basecamp Maasai Mara in Second Life was selected as the research site, designed and developed through a collaborative effort at Clemson University. The results revealed that technological acceptance factors of tele-presence, perceived usefulness and perceived ease-of-use as described by the Technology Acceptance Model are significant factors related to both virtual tourist experiences and the behavioral intentions. In addition, the results obtained here indicate that psychological needs of autonomy, competence, and relatedness, as specified by the Self-Determination Theory, are significantly associated with virtual tourist experiences and behavioral intentions. The results of this study suggest that in designing virtual destinations, tourism practitioners need to consider consumers\u27 psychological needs of competence, autonomy and relatedness; for instance, the activities provided in Second Life Maasai Mara such as riding animated animals and listening to Maasai music were found to increase the virtual tourist\u27s autonomy. In addition, tourism marketers should consider the types of information provided as well as the media used to present the information, by including videos and music, for example, in order to enhance the perception of ease-of use and usefulness. As technology continues to evolve, more research is needed to understand the significance of the use of virtual worlds in the tourism industry as well as to generate a new paradigm shift in tourism literature

Coding for Relay Networks with Parallel Gaussian Channels

A wireless relay network consists of multiple source nodes, multiple destination nodes, and possibly many relay nodes in between to facilitate its transmission. It is clear that the performance of such networks highly depends on information for- warding strategies adopted at the relay nodes. This dissertation studies a particular information forwarding strategy called compute-and-forward. Compute-and-forward is a novel paradigm that tries to incorporate the idea of network coding within the physical layer and hence is often referred to as physical layer network coding. The main idea is to exploit the superposition nature of the wireless medium to directly compute or decode functions of transmitted signals at intermediate relays in a net- work. Thus, the coding performed at the physical layer serves the purpose of error correction as well as permits recovery of functions of transmitted signals. For the bidirectional relaying problem with Gaussian channels, it has been shown by Wilson et al. and Nam et al. that the compute-and-forward paradigm is asymptotically optimal and achieves the capacity region to within 1 bit; however, similar results beyond the memoryless case are still lacking. This is mainly because channels with memory would destroy the lattice structure that is most crucial for the compute-and-forward paradigm. Hence, how to extend compute-and-forward to such channels has been a challenging issue. This motivates this study of the extension of compute-and-forward to channels with memory, such as inter-symbol interference. The bidirectional relaying problem with parallel Gaussian channels is also studied, which is a relevant model for the Gaussian bidirectional channel with inter-symbol interference and that with multiple-input multiple-output channels. Motivated by the recent success of linear finite-field deterministic model, we first investigate the corresponding deterministic parallel bidirectional relay channel and fully characterize its capacity region. Two compute-and-forward schemes are then proposed for the Gaussian model and the capacity region is approximately characterized to within a constant gap. The design of coding schemes for the compute-and-forward paradigm with low decoding complexity is then considered. Based on the separation-based framework proposed previously by Tunali et al., this study proposes a family of constellations that are suitable for the compute-and-forward paradigm. Moreover, by using Chinese remainder theorem, it is shown that the proposed constellations are isomorphic to product fields and therefore can be put into a multilevel coding framework. This study then proposes multilevel coding for the proposed constellations and uses multistage decoding to further reduce decoding complexity