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In this paper we present a new class of MAC protocols for wireless LANs based on sharing of transmission intentions. We develop an example protocol implementation based on distributed, co-operative scheduling of data frames. Sched- ules are non-binding, requiring minimal negotiation between nodes. The protocol is implemented on top of standard 802.11 so that backwards compatibility with legacy nod
This paper presents the findings from a design study of a model-based framework for safety-critical software development, called SimPal. The objective of the study was to better understand the necessary properties of such a framework and to learn more about the challenges of realizing it. Our research approach can be labeled as design research, which means that we try to answer our research questi
This paper presents a study of the so called far field approximation to the problem of determining both the direction to a number of transmittors and the relative motion of a single antenna using relative distance measurements. The same problem is present in calibration of microphone and wifi-transmittor arrays. In the far field approximation we assume that the relative motion of the antenna is sm
As the identification process is based on the unique patterns of the users, biometrics technologies are expected to provide highly secure authentication systems. The existing systems using fingerprints or retina patterns are, however, very vulnerable. One’s fingerprints are accessible as soon as the person touches a surface, while a high resolution camera easily captures the retina pattern. Thus,
Analytical Multiple-Input Multiple-Output (MIMO) models are often attractive due to their low complexity when analyzing possibilities and limitations in the system. In this paper we outline a a possible dual link extension of an analytical MIMO channel model and investigate its suitability based on measurements of a dual link MIMO scenario. The extension is based on the correlation matrix distance
As average packet sizes in wireless networks shrink and data rates increase, the fundamental CSMA mechanism in the 802.11 protocol family is put under stress. With the emerg- ing 802.11ax standard, the carrier sensing mechanism is low- ering the efficiency of the protocol to the level of random access (ALOHA), and as future-generation 802.11 standards emerge, CSMA-based protocols will fall below t
The phenomenon of adopting open source software development practices in a corporate environment is known by many names, one being inner source. The objective of this study is to investigate how an organization consisting of small development teams can benet from adopting inner source and assess the level of applicability. The research has been conducted as a case study at a software development c
This paper presents the main features of the TURNUS co-exploration environment, an unified design space exploration framework suitable for heterogeneous parallel systems designed using an high level dataflow representation. The main functions of this tool are illustrated through the analysis of a video decoder implemented in the RVC-CAL dataflow language.
In this paper we present an algorithm for finding low-weight multiples of polynomials over the binary field using coding theoretic methods. The code defined by the public polynomial is cyclic, allowing an attacker to search for any shift of the sought codeword. Therefore, a code with higher length and dimension is used, having a larger number of low-weight codewords. Additionally, since the degree of
Abstract in UndeterminedContextThe key for effective problem prevention is detecting the causes of a problem that has occurred. Root cause analysis (RCA) is a structured investigation of the problem to identify which underlying causes need to be fixed. The RCA method consists of three steps: target problem detection, root cause detection, and corrective action innovation. Its results can help with
Abstract in UndeterminedRoot cause analysis (RCA) is a structured investigation of a problem to detect the causes that need to be prevented. We applied ARCA, an RCA method, to target problems of four medium-sized software companies and collected 648 causes of software engineering problems. Thereafter, we applied grounded theory to the causes to study their types and related process areas. We detec
While Lars Norén’s confrontational and self-exposing En dramatikers dagbok (A Dramatist’s Journal, 2008) already has spurred discussions on the nature of confession in today’s mediatised literary public sphere, less has been said about the aesthetic project of the journal. By tracing this project back to Norén’s poetry of the 1960s as well as by comparing it to works by Lyn Hejinian and Kenneth Go
Multiple-input multiple-output (MIMO) is a mandatory feature of the Third Generation Partnership Project (3GPP) Long Term Evolution. This work investigates the performance of a low complexity channel estimator for LTE terminals with an emphasis on the 4 × 4 multiple antenna scheme. The presented work extends a promising low-complexity 2 × 2 MIMO channel estimator to the 4 × 4 MIMO case and evaluat
While research on the design of heterogeneous concurrent systems has a long and rich history, a unified design methodology and tool support has not emerged so far, and thus the creation of such systems remains a difficult, time-consuming and error-prone process. The absence of principled support for system evaluation and optimization at high abstraction levels makes the quality of the resulting im
Abstract in UndeterminedSoftware deployment, including both clean installs and updates, is a crucial activity for all software vendors. It starts with a customer's order of a new release and incorporates all steps taken until the customer is satisfied with the deployed product. Using interviews as the main data collection method, we conducted a case study of four companies to discover their softwa
