Non-orthogonal Multiple Access (NOMA) with Asynchronous Interference Cancellation

Non-orthogonal multiple access (NOMA) allows allocating one carrier to more than one user at the same time in one cell. It is a promising technology to provide high throughput due to carrier reuse within a cell. In this thesis, a novel interference cancellation (IC) technique is proposed for asynchronous NOMA systems, which uses multiple symbols from each interfering user to carry out IC. With the multiple symbol information from each interfering user the IC performance can be improved substantially. The proposed technique creates and processes so called "IC Triangles". That is, the order of symbol detection is based on detecting all the overlapping symbols of a stonger user before detecting a symbol of a weak user. Also, successive IC (SIC) is employed in the proposed technique. Employing IC Triangles together with the SIC suppresses co-channel interference from strong (earlier detected) signals for relatively weak (yet to be detected) signals and make it possible to achieve low bit error rate (BER) for all users. Further, iterative signal processing is used to improve the system performance. Employing multiple iterations of symbol detection which is based on exploiting a priori estimate obtained from the previous iteration can improve the detection and IC performances. The BER and capacity performance analyses of an uplink NOMA system with the proposed IC technique are presented, along with the comparison to orthogonal frequency division multiple access (OFDMA) systems. Performance analyses validate the requirement for a novel IC technique that addresses asynchronism at NOMA uplink transmissions. Also, numerical and simulation results show that NOMA with the proposed IC technique outperforms OFDMA for uplink transmissions. It is also concluded from the research that, in the NOMA system, users are required to have large received power ratio to satisfy BER requirements and the required received power ratio increases with increasing the modulation level. Also, employing iterative IC provides significant performance gain in NOMA and the number of required iterations depend on the modulation level and detection method. Further, at uplink transmissions, users' BER and capacity performances strongly depend on the relative time offset between interfering users, besides the received power ratio

Performance of Non-orthogonal Multiple Access (NOMA) with a Novel Asynchronous Interference Cancellation Technique

The non-orthogonal multiple access (NOMA) allows one subcarrier to be allocated to more than one user at the same time in an orthogonal frequency division multiplexing (OFDM) system. NOMA is a promising technique to provide high throughput due to frequency reuse within a cell. In this paper, a novel interference cancellation (IC) technique is proposed for asynchronous NOMA systems. The proposed IC technique exploits a triangular pattern to perform the IC from all interfering users for the desired user. The bit error rate (BER) and capacity performance analysis of an uplink NOMA system with the proposed IC technique is presented, along with the comparison to orthogonal frequency division multiple access (OFDMA) systems. The numerical and simulation results show that the NOMA with the proposed asynchronous IC technique outperforms the OFDMA. It is also shown that employing iterative IC provides significant performance gain for NOMA and the number of required iterations depends on the modulation level and the detection method.With hard-decision, two iterations are sufficient, however with soft-decision, two iterations are enough only for low modulation level, and more iterations are desirable for high modulation level

A Proposal for Dynamic Frequency Sharing in Wireless Networks

Wireless networks are today employed as complementary access technology, implemented on the last hop towards the Internet end-user. The shared media that wireless deployments provide and which is relevant to interconnect multiple users has a limited technical design, as only one device can be served per unit of time, design aspect that limits the potential applicability of wireless in dense environments. This paper proposes and evaluates a novel MAC-layer mechanism that extends current wireless networks with the possibility to perform downstream transmission to multiple devices within a single transmission time-frame, resulting in improved fairness for all devices. The mechanism, which is software-defined, is backward-compatible with current wireless standards and does not require any hardware changes. The solution has been validated in a realistic testbed, and the paper provides details concerning the computational aspects of our solution; a description of the implementation; and results extracted under different realistic scenarios in terms of throughput, packet loss, as well as jitter

Depredadores de escarabajos de la corteza (Coleoptera) en la región de Balikesir de Turquía.

El objetivo de este estudio fue determinar la diversidad de los depredadores de los escarabajos de la corteza en los bosques de coníferas de la provincia de Balıkesir en Turquía. Se establecieron seis parcelas que contenían cinco trampas de feromonas y dos trampas de troncos. Se encontraron ocho especies de depredadores de escarabajos de corteza: Aulonium ruficorne (Olivier, 1790), Clerus mutillarius Fabricius 1775, Corticeus fraxini (Kugelann, 1794), Paromalus parallelepipedus (Herbst, 1792), Platysoma elongatum (Thunberg, 1782), Raphidia ophiopsis Linnaeus 1758, Temnochila caerulea (Olivier, 1790) y Thanasimus formicarius (Linnaeus, 1758), pertenecientes a seis familias: Cleridae, Trogossitidae, Laemophloeidae, Tenebrionidae, Zopheridae, Histeridae, Raphidiidae. También se describe en cuáles galerías de escarabajos se encontraban estos depredadores

Impact of Coronary Collateral Circulation on In-Hospital Death in Patients with Inferior ST Elevation Myocardial Infarction

Objectives. Coronary collateral circulation (CCC) may limit the size of right ventricular (RV) infarcts but does not fully explain the relationship between CCC and clinical adverse events in patients with inferior STEMI. In this study, it was aimed to assess the relationship between preintervention angiographic evidence of CCC and clinical outcomes in patients with inferior STEMI who have undergone percutaneous coronary intervention. Methods. A total of 235 inferior STEMI patients who presented within the first 12 hours from the symptom onset were included. CCC to the right coronary artery (RCA) before angioplasty were angiographically assessed, establishing two groups: 147 (63%) patients without CCC and 88 (37%) with CCC according to presence of CCC. Results. RV infarction, complete atrioventricular block, VT/VF, cardiogenic shock, and in-hospital death were noted less frequently in patients with CCC than in those without CCC. Absence of CCC to RCA was found to be the independent predictor for in-hospital death among them (odds ratio 4.0, 95% CI 1.8–12.6; p=0.03). Conclusion. Presence of angiographically detectable CCC was associated with better in-hospital outcomes including RV infarction, complete AV block, cardiogenic shock, and VT/VF in patients with inferior STEMI

Varför ränta? : Ett räntekritiskt perspektiv

I dagens samhälle är det nästintill omöjligt att inte stöta på ränta. Förr eller senare kommer individen i behov av att låna pengar. Behovet av att låna kapital och placera sparandeöverskott koordineras på kreditmarknaden. Ränteverksamhet är den alltmer dominerande formen. Trots att ränta använts under flera århundraden, har det funnits kritiker mot ränta, under en lika lång tid. Syftet med uppsatsen är att genom räntekritikernas perspektiv redogöra för varför ränteekonomin är problematisk och varför vi eventuell skall ha en räntefri ekonomi istället för den vanliga ränteekonomin. Metodiskt är uppsatsen grundat på sekundär- och primärdata. Med ändamålet att besvara de frågor som jag ställer i uppsatsen, har jag använt mig av intervjuer och en mindre art av fallstudie. Definitionen på ränta varierar, men enkelt kan man säga att det är ersättning till olika produktionsfaktorer som exempelvis mark och kapital. I studien har det framkommit att räntekritikernas skäl varit varierande. De flesta kritikerna påstår att ränta leder till att en kapitalström går från fattiga till rika. Med andra ord är räntan till gagn för de individer som redan har gott om pengar. Vid sidan av det förekommer andra skäl. Från religionens sida sägs det att räntan är ett hinder för ett specifikt ändamål. Således är slopande av ränta ett medel för att nå ett religiöst mål. Kritiken har lett till att diverse räntefria verksamheter uppkommit. Dessa har dock brister. JAK medlemsbank fungerar bra för dess medlemmar som tänker spara och låna på en längre sikt. Islamiska banker har enligt uppgifter en bra avkastning, men till skillnad från förra banken är den lämpligare för kortare in- respektive utlåningar. Det mesta av räntekritikernas argument och åsikter är lagt fram på ett övertygande sätt, med belägg och siffror hämtade från statliga instanser. Ett total räntefritt samhälle lär inte byggas upp i den närmaste framtiden, men däremot kan det mycket väl vara så att flera räntefria verksamheter dyker upp, samt att de befintliga verksamheternas medlemmar och kunder ökar

Novel scheduling characteristics for mixture of real-time and non-real-time traffic

This paper presents comprehensive performance analyses of a novel scheduling policy for wireless communications where users have mixed real-time (RT) and non-real-time (nRT) traffic. Also, it introduces novel characteristics to scheduling where the QoS perceived by RT and nRT streams within a mixed traffic system can be differentiated and managed. Performance comparisons with popular proportional fair scheduling policy as well as the convergence analysis are also included

Performance of non-orthogonal multiple access with a novel interference cancellation method

In this paper, a novel interference cancellation technique is proposed for asynchronous non-orthogonal multiple access (NOMA) systems and the performance is theoretically investigated in a small cell uplink scenario. It is shown that unlike synchronous communications, at uplink transmission, NOMA users' performance strongly depends on the relative time offset between interfering users

Predators of bark beetles (Coleoptera) in the Balikesir region of Turkey

El objetivo de este estudio fue determinar la diversidad de los depredadores de los escarabajos de la corteza en los bosques de coníferas de la provincia de Balıkesir en Turquía. Se establecieron seis parcelas que contenían cinco trampas de feromonas y dos trampas de troncos. Se encontraron ocho especies de depredadores de escarabajos de corteza: Aulonium ruficorne (Olivier, 1790), Clerus mutillarius Fabricius 1775, Corticeus fraxini (Kugelann, 1794), Paromalus parallelepipedus (Herbst, 1792), Platysoma elongatum (Thunberg, 1782), Raphidia ophiopsis Linnaeus 1758, Temnochila caerulea (Olivier, 1790) y Thanasimus formicarius (Linnaeus, 1758), pertenecientes a seis familias: Cleridae, Trogossitidae, Laemophloeidae, Tenebrionidae, Zopheridae, Histeridae, Raphidiidae.  También se describe en cuáles galerías de escarabajos se encontraban estos depredadores.The aim of this study was to determine the diversity of bark beetle predators in the coniferous forests of the Balıkesir Province of Turkey. Six plots were established that each contained five pheromone traps and two log traps. Eight bark beetle predator species: Aulonium ruficorne (Olivier, 1790), Clerus mutillarius Fabricius 1775, Corticeus fraxini (Kugelann, 1794), Paromalus parallelepipedus (Herbst, 1792), Platysoma elongatum (Thunberg, 1782), Raphidia ophiopsis Linnaeus 1758, Temnochila caerulea (Olivier, 1790) and Thanasimus formicarius (Linnaeus, 1758), belonging to six families were found. The six bark beetle predator families found were: Cleridae, Trogossitidae, Laemophloeidae, Tenebrionidae, Zopheridae, Histeridae, and Raphidiidae. Also it is included a description of which bark beetle galleries these predators were found in