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In this letter we apply the Generalized Method of Moments (GMM), widely used in econometrics, to receivers operating with imperfect channel state information (CSI) of singleinput-multiple-output (SIMO) block-fading channels where a single pilot symbol is used. The GMM results in the standard maximum ratio combining (MRC) receiver, but with an improved channel estimate. Although not our goal at the

This paper presents a mutual coupling based calibration method for time-division-duplex massive MIMO systems, which enables downlink precoding based on uplink channel estimates. The entire calibration procedure is carried out solely at the base station (BS) side by sounding all BS antenna pairs. An Expectation-Maximization (EM) algorithm is derived, which processes the measured channels in order t

During the last two decades a slow but steady change of external factors has set-up new conditions affecting the way in how software producing firms create and leverage innovations. Firms now need to look outside of their boundaries and start interacting with the open environment that encompasses them in order to stay innovative and keep a competitive advantage. To facilitate this shift Requiremen

[Context and motivation] Ecosystems developed as Open Source Software (OSS) are considered to be highly innovative and reactive to new market trends due to their openness and wide-ranging contributor base. Participation in OSS often implies opening up of the software development process and exposure towards new stakeholders. [Question/Problem] Firms considering to engage in such an environment sho

In the vehicular communication channels, the mobility of the receiver (RX) and the transmitter (TX) along with the movements of interacting objects in the propagation environment result in significant non-stationary channel fading. The channel impulse response exhibits not just significant delay- and Doppler spreads, but also the delay- and Doppler spreads themselves are changing over the time- an

This paper presents the construction and evaluation of SERP-test, a taxonomy aimed to improve communication between researchers and practitioners in the area of software testing. SERP-test can be utilized for direct communication in industry academia collaborations. It may also facilitate indirect communication between practitioners adopting software engineering research and researchers who are st

We consider the problem of migrating keys from TPM 1.2 to the backwardsincompatible TPM 2.0. The major differences betweenthe two versions introduce several challenges for deployed systems whensupport for TPM 2.0 is introduced. We show how TPM 2.0 support can beintroduced while still maintaining the functionality specified by TPM 1.2,allowing a smoother transition to the newer version. Specificall

A wide band fractional-N digital PLL which uses a high resolution 2-dimension gated-Vernier time-to-digital converter (TDC) with 5.2 ps resolution is presented. The quantization noise shaping of the TDC greatly improves the in-band phase noise. While, in the same time, the 2-dimension structure makes the digital PLL (DPLL) be able to process large phase errors almost without the influence of laten

In this work we implement features for IEEE 802.11ac in the NS-3 simulator, in particular wider channels and bit-error calculations for higher modulation coding schemes. We also implement four wireless LAN deployment scenarios from the 802.11ax working group scenario document, and evaluate their performance under different operating conditions. Our simulation results demonstrate that many nodes in

Block diagram languages are often used for physical modeling and automation, where end users are domain engineers that instantiate block types and wire them together. Abstraction mechanisms in these languages allow specialists to build advanced reusable domain-specific libraries. However, this brings a tension between supporting reusability and making the language simple to comprehend for domain e

Ensuring that communication is secure, including the ability to encrypt sensitive traffic, has always been a fundamental pillar of the telecom industry. Users expect their right to privacy to be respected, and operators expect to be able to protect themselves and their customers from various kinds of attacks. But the world is changing. Encryption technologies are advancing, regulations are changin

We consider optimal precoder design for multi-user multiple-input multiple-output (MIMO) broadcasting channels in single-carrier (SC) systems. Instead of linear detection, we assume that advanced non-linear channel shortening (CS) detectors are utilized at the receivers. Such a scenario is challenging for precoder design as the uplink-downlink duality is inapplicable. The target of our linear prec

In LTE base-stations, RoHC is a processingintensive algorithm that may limit the system from serving a large number of users when it is used to compress the VoIP packets of mobile traffic. In this paper, a hardware-software and a full-hardware solution are proposed to accelerate the RoHC compression algorithm in LTE base-stations and enhance the system throughput and capacity. Results for both sol

Case studies are largely used for investigating software engineering practices. They are characterized by their flexible nature, multiple forms of data collection, and are mostly informed by qualitative data. Synthesis of case studies is necessary to build a body of knowledge from individual cases. There are many methods for such synthesis, but they are yet not well explored in software engineerin

This brief presents a low-complexity system for digitally assisting a channel select filter (CSF) to mitigate both even- and odd-order nonlinearities. The proposed solution is scalable and can be utilized for nonlinearity mitigation in different analog transceiver blocks. The system consists of an auxiliary path with a low-resolution analog to digital converter (ADC) enabling digital recreation an

[Context and motivation] When developing software, coordination between different organizational units is essential in order to develop a good quality product, on time and within budget. Particularly, the synchronization between requirements and verification processes is crucial in order to assure that the developed software product satisfies customer requirements. [Question/problem] Our research

Feedback with carry shift registers (FCSRs) have previously been available in two configurations, the Fibonacci and Galois architectures. Recently, a generalized and unifying FCSR structure and theory was presented. The new ring FCSR model repairs some weaknesses of the older architectures. Most notably, the carry cell bias property that was exploited for an attack on the eSTREAM final portfolio c

Abstract in UndeterminedSignal detection algorithms providing likelihood informationfor coded spatial-multiplexing multiple-input multipleoutput(MIMO) wireless communication system pose a criticaldesign challenge due to their prohibitively high computationalcomplexity. In this paper, we present a low-complexity soft-outputdetection algorithm by adopting four implementation-friendlyalgorithm-level

Characteristic mode analysis provides unparalleled insights into designing high performance multiple-input multiple-output (MIMO) terminal antennas at frequencies where the antenna elements are constrained to be electrically small. Conventionally, an electrically small single-antenna utilizes the fundamental characteristic mode of the terminal chassis to obtain sufficient bandwidth while maintaini