Multi-user lattice coding for the multiple-access relay channel

This paper considers the multi-antenna multiple access relay channel (MARC), in which multiple users transmit messages to a common destination with the assistance of a relay. In a variety of MARC settings, the dynamic decode and forward (DDF) protocol is very useful due to its outstanding rate performance. However, the lack of good structured codebooks so far hinders practical applications of DDF for MARC. In this work, two classes of structured MARC codes are proposed: 1) one-to-one relay-mapper aided multiuser lattice coding (O-MLC), and 2) modulo-sum relay-mapper aided multiuser lattice coding (MS-MLC). The former enjoys better rate performance, while the latter provides more flexibility to tradeoff between the complexity of the relay mapper and the rate performance. It is shown that, in order to approach the rate performance achievable by an unstructured codebook with maximum-likelihood decoding, it is crucial to use a new K-stage coset decoder for structured O-MLC, instead of the one-stage decoder proposed in previous works. However, if O-MLC is decoded with the one-stage decoder only, it can still achieve the optimal DDF diversity-multiplexing gain tradeoff in the high signal-to-noise ratio regime. As for MS-MLC, its rate performance can approach that of the O-MLC by increasing the complexity of the modulo-sum relay-mapper. Finally, for practical implementations of both O-MLC and MS-MLC, practical short length lattice codes with linear mappers are designed, which facilitate efficient lattice decoding. Simulation results show that the proposed coding schemes outperform existing schemes in terms of outage probabilities in a variety of channel settings.Comment: 32 pages, 5 figure

Filter and nested-lattice code design for fading MIMO channels with side-information

Linear-assignment Gel'fand-Pinsker coding (LA-GPC) is a coding technique for channels with interference known only at the transmitter, where the known interference is treated as side-information (SI). As a special case of LA-GPC, dirty paper coding has been shown to be able to achieve the optimal interference-free rate for interference channels with perfect channel state information at the transmitter (CSIT). In the cases where only the channel distribution information at the transmitter (CDIT) is available, LA-GPC also has good (sometimes optimal) performance in a variety of fast and slow fading SI channels. In this paper, we design the filters in nested-lattice based coding to make it achieve the same rate performance as LA-GPC in multiple-input multiple-output (MIMO) channels. Compared with the random Gaussian codebooks used in previous works, our resultant coding schemes have an algebraic structure and can be implemented in practical systems. A simulation in a slow-fading channel is also provided, and near interference-free error performance is obtained. The proposed coding schemes can serve as the fundamental building blocks to achieve the promised rate performance of MIMO Gaussian broadcast channels with CDIT or perfect CSITComment: submitted to IEEE Transactions on Communications, Feb, 200

Understanding the Antecedents of SCM Process Performance: The Perspective of IT-Enabled Resources

This study aims to better understand how a firm’s resources can be used to improve performance of supply chain. Extending prior research on the resources-based view, this study develops an integrated model, which delineates the relationship among three IT-related resources, absorptive capacity, and supply chain (SC) process performance. Through a field survey of 205 managers from Taiwan’s firms, most proposed hypotheses are supported, showing that IT-related resources in terms of managerial skills and partner support affect absorptive capacity, which in turn influences performance. This paper offers a new perspective on using firms’ resources from which their SC performance can be improved

Understanding Satisfaction With Service Providers From The Resource-Based View Of A Firm

Drawing on the resource-based view (RBV), the aim of this research is to better understand how satisfaction with application service providers (ASPs) is affected by intangible assets in interorganizational relationships (e.g. antecedents of non-contractibility), which in turn are influenced by IT-enabled resources such as information systems (IS) integration and ambidexterity of software development. Empirical findings support the proposed model. We discuss the implications for practitioners and research

Prediction Markets: A Systematic Review and Meta-Analysis

Prediction markets (PM) have drawn considerable attention in recent years as a tool for forecasting events. Studies surveying and examining relevant the trends of PM using traditional approaches have been reported in the literature. However, research using meta-analysis to review Prediction markets systems is very limited in Management Information System (MIS). This paper aimed to fill this gap by using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method to study Prediction markets trends over the past decades. Our results are as follows. First, we find that shows that more than 64% of academic studies on Prediction markets are published in top journals such as Journal of the Association for Information Systems, Journal of Consumer Research and Information Systems Research. Second, we showed that Prediction markets applications can be can be divided into two groups: internal use PMS and general public usage. Finally, our significant meta-analysis result show that on average prediction markets is 79% more accurate than alternative forecast methods based

Text Mining-Based Patent Analysis of Blockchain Technology Applications

This study focuses on the emergence of blockchain-related technologies regarding patenting activity. Blockchain technology has gained the attention of the general public. It has intensified in recent years, making it a fascinating subject of study for a patent analysis to scrutinize the evolution of this technology. However, research using the patent landscape to study the evolution of blockchain technologies is scarce. This article follows a unique methodology and comprehensive search strategy based on patent mapping and text mining to identify and categorize Blockchain patent documents extracted from the United States Patent and Trademark Office and the World Intellectual Property Organization databases. This methodology and dataset can be used for patent landscaping exercises or bibliometric analysis

Cognitive Radio with Partial Channel State Information at the Transmitter

In this paper, we present the cognitive radio system design with partial channel state information known at the transmitter (CSIT).We replace the dirty paper coding (DPC) used in the cognitive radio with full CSIT by the linear assignment Gel'fand-Pinsker coding (LA-GPC), which can utilize the limited knowledge of the channel more efficiently. Based on the achievable rate derived from the LA-GPC, two optimization problems under the fast and slow fading channels are formulated. We derive semianalytical solutions to find the relaying ratios and precoding coefficients. The critical observation is that the complex rate functions in these problems are closely related to ratios of quadratic form. Simulation results show that the proposed semi-analytical solutions perform close to the optimal solutions found by brute-force search, and outperform the systems based on naive DPC. Asymptotic analysis also shows that these solutions converge to the optimal ones solved with full CSIT when the K-factor of Rician channel approaches infinity. Moreover, a new coding scheme is proposed to implement the LA-GPC in practice. Simulation results show that the proposed practical coding scheme can efficiently reach the theoretical rate performance.Comment: resubmitted to IEEE Transaction on Wireless Communications, May 200

The Contribution of Commitment Value in Internet Commerce: An Empirical Investigation

Exploring what makes Internet customers satisfied is perhaps one of the most important challenges facing customer relationship managers in this decade. It is important because prior studies suggest that happy customers make repeat purchases and develop brand loyalty. However, there is not enough accumulated knowledge to understand specifically the determinants of customer satisfaction in Internet commerce. To more accurately understand the determinants that may enhance a customer\u27s satisfaction with their Internet shopping experience, this study looks at the customer\u27s commitment value and examines its relationships with the customer\u27s satisfaction. Commitment value is defined as a total value perception from a buyer and is composed of three components: sociopsychological, economic, and product values. The results from this study show that the sociopsychological value (i.e., shopping enjoyment and convenience in purchasing) and the product value (i.e., product quality) contribute significantly to the attainment of customer satisfaction. The economic value (i.e., reduction of time spent in Internet shopping), however, has no significant positive impact on customer satisfaction. Explanations are presented along with the implications