No description available.

No description available.

Future wireless communication systems will utilize the spatial properties of the wireless channel to improve the spectral efficiency and thus increase capacity. This is realized by deploying multiple antennas at both the transmitter and receiver. Utilizing the spatial properties of the channel demands channel models that properly reflect these characteristics. Due to the unpredictable nature of the wireless channel, a common approach is to model its effects in a statistical fashion. A few large world wide cooperations, like the 3GPP or WINNER projects, have developed channel models intended for reference and standardization use. These models are partly based on bulk parameters which describe the characteristics of the channel over larger areas of several wavelengths. These parameters include shadow fading, angle spread, and delay spread among others, and are within the WINNER project called large scale (LS) parameters. Considering the variations of these parameters, it is likely that they are correlated between closely located areas. Therefore it is of key interest to model their correlation properties instead of randomizing them independently for each new simulation. In multi-cell scenarios, when considering macro diversity or evaluation other properties such as interference and/or handover schemes, the intra site correlation of the shadow fading parameters should be taken into account for proper simulations. Neglecting this correlation the interference could be over/under estimated, hence the system capacity can be over/under estimated. Further, reliable estimations of the interference levels will increase the frequency reuse, and may even permit reuse within the same cell, on spatially separated links. The thesis focuses on modelling the statistics and variations of these parameters to increase accuracy of channel models. Previous studies have looked at the autocorrelation properties of the shadow fading in outdoor environments and found it to follow an exponential decay. This means that an first order autoregressive function would be sufficient to model this effect. Research of the angular spread parameter is more scarce, and therefor this issue is studied herein. In addition to the autocorrelation properties the intra-site correlation between the different large scale parameters is of interest. It is herein found that the shadow fading is negatively correlated with angle spreads, while the angle spread at the base station and the angle spread at the mobile show positive correlation. Finally, the inter site correlation between one mobile and multiple base stations is studied as a function of the angular separation between the links. For closely located base station, ie with small angular separation as seen from the mobile, substantial inter-site correlation is found. It is further seen that the correlation of the shadow fading is more prominent than the correlation of angle spread. / QC 20101109

No description available.

No description available.

No description available.

No description available.

In this dissertation, my focus is on understanding distribution channel conflict, its relationship with efficient channel governance and its impact on channel performance. In particular, I will study (1) how the channel conflict can be defined and interpreted, (2) how channel conflict can affect channel governance, (3) what would be the performance outcomes of channel conflict, and (4) how channel conflict can be managed. My theoretical frameworks borrow mainly from transaction cost economics theory (TCE), and strategic marketing. On the empirical side, I employ several methods including meta-analysis (Two-Stage SEM) as well as different econometrics techniques such as Conditional Mixed-Process (CMP) regression estimation. My data comes from diverse sources and are mainly hand collected and created from archival sources. For the meta-analysis study, I extract empirical results of more than 100 studies on channel conflict since the 1960s. For the other empirical efforts, the data comes from various sources. The major data collection undertakings include extracting and integrating data from: (1) Franchise Disclosure Document (FDD) of more than 1000 franchise firms, (2) firms records, and (3) specific franchise rankings such as Entrepreneur and Franchise Times’ rankings spanning from 2004 to 2015. The dissertation comprises following broad inter-related chapters (excluding Introduction and Conclusion chapters): (1) Managing Channel Conflict: Insights from the Current Literature, (2) Conflict and Performance in Channels: A Meta-Analysis, (3) Channel Conflict: Bad for Business?, (4) Adapting to Channel Conflict: An Empirical Study?, and (5) Two Views on Channel Conflict. Chapter 1 is a compendium on channel conflict that not only provides a comprehensive literature review on channel conflict (since the 1960s) but also identifies gaps and provides some managerial perspectives on channel conflict. One of the identified gaps in Chapter 1 revolves around the role of channel conflict and its relationship with other inter-firm constructs. In Chapter 2, I build on this identified gap by conducting a comprehensive meta-analysis study using Two-Stage SEM (TSSEM) method to aggregate the previous findings on channel conflict and its relationship with other inter-firm constructs particularly channel performance. I also investigate the potential moderators of the conflict-performance link. Chapters 1 and 2 set the stage for the next empirical work. One of the enduring debates in the channel domain is about the functionality and dysfunctionality of channel conflict. In Chapter 3, I address this directly by exploring the non-linear (inverted U-shaped) relationship between channel conflict and performance. While Chapter 3 explores the empirical relation between conflict and performance, another understudied but important research question is about how firms react to channel conflict. Such reactions can span the range from relying on relational norms to more explicit adjustment in channel governance. In Chapter 4, I address this by examining the effect of manifest channel conflict on channel governance, controlling for relational norms. In particular, I study how firms adapt their channel governance following litigation. Finally, Chapter 5 is a reflection on the body of knowledge that I have investigated above. This chapter will provide two views on channel conflict by comparing two different channel conflict conceptualizations. I illustrate the differences between these two views by comparing them based on firms’ objectives, conflict characteristics, and managerial approaches toward channel conflict, providing real-world examples of how firms approach and manage channel conflict. / Thesis / Doctor of Philosophy (PhD) / In this dissertation, my focus is on understanding distribution channel conflict, its relationship with efficient channel governance and its impact on channel performance. Channel conflict is an endemic phenomenon. The advent of new technologies (such as Internet-of-Things enabled monitoring systems) and the emergence of the Internet as a primary medium of business transactions have brought big changes to channel management. Use of multiple channels to reach consumers and exchange value with business partners have become much more common with these changes. While channel conflict has always been an important business concern, these have rekindled the interest and attention of researchers and managers to the phenomena. In this dissertation, I investigate the phenomenon of channel conflict and its effect on channel governance and business performance by conducting several independent studies spanning different research methods. The research findings will address gaps in the extant research literature as well as offer both theoretical and practical insights for researchers and practitioners interested in distribution channels strategy and management.

Diese Diplomarbeit befasst sich mit mehreren Unterthemen der verdeckten Kommunikationskanäle (Covert Channels) und möchte vor allen Dingen neue Themen vorstellen und diskutieren: Erstmalige und detaillierte Behandlung von Protocol Hopping Covert Channels: Protocol Hopping Covert Channels sind Storage Channels die, während sie existieren, das Netzwerkprotokoll, in dem die versteckten Informationen untergebracht werden, wechseln. Vorstellung der Idee der Protocol Channels: Im Gegensatz zu Protocol Hopping Covert Channels sind Protocol Channels schwerer zu detektieren, da sie ausschließlich durch den Wechsel eines Protokolls (ohne zusätzliche Informationen zu verstecken), versteckte Daten übertragen. Sowohl für Protocol Hopping Covert Channels als auch für Protocol Channels beschreibt diese Arbeit deren jeweilige Technik und untersucht deren Detektionsmöglichkeiten. Vorstellung der Idee der Header-Strukturveränderung: Ziel der Header-Strukturveränderung ist es, die Möglichkeiten, die Angreifer bei der Erstellung von Storage Channels innerhalb von Paket-Headern haben, einzugrenzen. Bei der Header-Strukturveränderung wird der Aufbau von Paket-Headern für jedes neu verschickte Paket verändert. Eine entsprechende Strukturinformation, die den Headeraufbau bestimmt, ist nur vertrauenswürdigen Komponenten beim Empfänger bzw. Sender zugänglich. Diese Arbeit stellt sowohl ein theoretisches Modell der Header-Strukturveränderung als auch eine praktische Umsetzung vor.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Data collected during July 1999 at Edwards EAFB by the Advanced Range Telemetry (ARTM) program is examined to characterize the dynamic behavior of multipath interference in an aeronautical telemetry channel. Multipath fade events are analyzed in the frequency domain to show how these fades appear, evolve, and disappear from the channel. A channel model and examples from the channel sounding data are used to show the dynamic nature of these fade events. The Doppler power spectrum is used to quantify the exact time-varying nature of the multipath fade events. The coherence time, or the amount of time the channel can be viewed as unchanging, is obtained from the Doppler power spectrum and is calculated to be 100 ms in the data sets examined in this paper. This implies that adaptive multipath mitigation techniques must have an adaptation bandwidth of 10 Hz.