A blind signal localization and SNR estimation method

ABSTRACT Congested radio frequencies call for efficient and flexible spectrum use and, hence, spectrum sensing. As cognitive radios need channel information for achieving better use of radio frequencies, military systems require information about unknown signals. In this paper, a novel method for computing signal-to-noise ratios (SNR) of several unknown narrowband signals without a priori information is proposed. The presented frequency domain method is an extension of the localization algorithm based on double-thresholding (LAD). The main point is to produce fast and cost-efficient estimators with adequate accuracy. The proposed method is verified via computer simulations and tested also with real-life radio channel measurement data. The results verify that the proposed method gives sufficient approximations of SNR values with low overall computational complexity

6G for Bridging the Digital Divide: Wireless Connectivity to Remote Areas

In telecommunications, network service accessibility as a requirement is closely related to equitably serving the population residing at locations that can most appropriately be described as remote. Remote connectivity, however, would have benefited from a more inclusive consideration in the existing generations of mobile communications. To remedy this, sustainability and its social impact are being positioned as key drivers of the sixth generation's (6G) research and standardization activities. In particular, there has been a conscious attempt to understand the demands of remote wireless connectivity, which has led to a better understanding of the challenges that lie ahead. In this perspective, this article overviews the key challenges associated with constraints on network design and deployment to be addressed for providing broadband connectivity to rural areas, and proposes novel approaches and solutions for bridging the digital divide in those regions

A 6G White Paper on Connectivity for Remote Areas

In many places all over the world rural and remote areas lack proper connectivity that has led to increasing digital divide. These areas might have low population density, low incomes, etc., making them less attractive places to invest and operate connectivity networks. 6G could be the first mobile radio generation truly aiming to close the digital divide. However, in order to do so, special requirements and challenges have to be considered since the beginning of the design process. The aim of this white paper is to discuss requirements and challenges and point out related, identified research topics that have to be solved in 6G. This white paper first provides a generic discussion, shows some facts and discusses targets set in international bodies related to rural and remote connectivity and digital divide. Then the paper digs into technical details, i.e., into a solutions space. Each technical section ends with a discussion and then highlights identified 6G challenges and research ideas as a list.Comment: A 6G white paper, 17 page

Delay Estimation in the Presence of a Tone Jammer: Two Simple Estimators

Two delay estimators that mitigate effects of a tone jammer are presented. They are based on the phase interference extractor (PIE) and auxiliary-vector (AV) data detection principles. The estimators are analyzed by computer simulations and shown to tolerate more powerful jammers than the conventional correlator estimator does

A Performance Study of the MVDR Delay Estimator in the Presense of Interference

The performance of the minimum variance distortionless response (MVDR) estimator is studied by simulations if the estimator is applied for delay estimation of a direct sequence spread spectrum (DS/SS) signal corrupted by interference. The results show that the MVDR estimator can mitigate the effects of strong tone interferences and other DS/SS signals, under the condition that the number of other DS/SS signals is limited to one third of the code length. However, the estimator is quite sensitive to a highly correlated multipath signal

Asymptotic distributions of the correlator and maximum likelihood estimators of nonlinear signal parameters

Abstract In time delay estimation the correlator or, equivalently, matched filter estimator is widely used. Examples of its usage can be found in the global positioning system (GPS), radars and code division multiple access (CDMA) communication systems. Although widely used its performance is not studied in general case until recently. Partially this study is done in this thesis. If interfering signals like multipath or multiple access signals exist in addition to additive white Gaussian noise, as in GPS and CDMA, the correlator is not a maximum likelihood (ML) estimator. However, it is known that the correlator produces consistent estimates in the existence of multipath interference if the delay separation is larger than the correlation time of the signal (in direct sequence spread spectrum applications such as GPS and CDMA, the correlation time approximately equals the chip duration of the spreading code). It also performs well in the existence of multiple access interference (MAI), if the powers of the MAI signals are equal to the power of the desired signal. In this thesis the asymptotic distribution of the correlator estimator is derived in multisignal environments. Using the result, it can be analytically shown, that in these benign interference cases the exact ML estimator and the correlator estimators perform equally well in the sense that their asymptotic covariance matrices are equal. The thesis also verifies the well known result that if the signals are orthogonal, then the correlator and ML estimators perform equally. In addition, the correlator's asymptotic performance is investigated also in the inconsistent case by slightly extending the earlier results found in the literature. Also the resolution of the correlator estimator is investigated. It is numerically shown that the correlator estimator can produce consistent estimators even if the delay separation is less that the chip duration, which is commonly believed to be the resolution limit of the correlator. This can happen in fading channels where the multipath amplitudes are uncorrelated or just slightly correlated. This result seems to be fairly unknown. In addition to the classical ML estimator, where all the unknowns are assumed to be deterministic, also an improved ML estimator is investigated. This other ML estimator is obtained by assuming that the amplitudes are Gaussian distributed. It is an improved estimator in the sense that its asymptotic covariance, say CML, is less positive definite than that of the classical ML estimator CCML, i.e., CCML-CML is positive semidefinite. More importantly, this result is valid independent of the fact are the amplitudes really deterministic or Gaussian. This well known result is shown in this thesis to be valid also if the signals contain more than one unknown parameter, which occurs, for example, in direction-of-arrival estimation when two angles per arrival are to be estimated

Systematic Errors and Location Accuracy in Wireless Networks

Wireless systems already provide time delay and signal strength measurements and the future may see antenna arrays that provide directional information. All these may be used for positioning. Although the statistical accuracy of different positioning methods is well studied, the systematic error effects, which arise, for example, from errors in sensor (node) location, network synchronization, or the path loss model, are not. This study fills this gap providing a unified error-propagation-law-based tool to analyze measurement and systematic error effects. The considered positioning systems, which are compared based on the developed framework, are the hyperbolic (time-delay-based), direction finding (DF), received signal strength (RSS), and relative RSS (RRSS) location systems. The obtained analytical results verify our intuitive expectations; the hyperbolic methods are sensitive to errors in network synchronization, RRRS methods to channel modelling errors, whereas DF methods are rather insensitive to systematic errors. However, the bias of DF methods is at its largest if the sensor location error is perpendicular to the line joining the sensor and the source. If the methods are compared based on overall accuracy, hyperbolic methods may be preferred in large sized networks, whereas the DF and RRSS methods may provide better accuracy in small sized networks. However, RRSS systems require a dense network in order to provide reliable results.</p

Detaljplanering : Exploatering inom ett område av riksintresse

Arbetet utreder förutsättningarna att exploatera ett område i Trångfors i Bodens kommun för bostadsändamål arbetet är på uppdrag av Bodens kommuns plankontor. Parallellt med utredningen tas ett förslag på detaljplan och tillhörande handlingar framför området som redovisas i rapporten. Detaljplanen ritas i programmet Focus detaljplan som plankontoret i Boden använder. Under den verksamhetsförlagda utbildningen på Bodens plankontor är ett underlag är framtaget, materialet ligger som grund till rapporten samt detaljplanens bestämmelser och utformning. Under arbetet har dialog förts med berörda förvaltningar samt Länsstyrelsen. Detaljplanering avser att reglera hur mark-och vattenområden inom kommunen ska användas, vilket ändamål ett område är mest lämpat för baseras på områdets läge behov och egenskaper. Lagar som främst reglerar planläggning av mark-och vattenområden är Plan-och bygglagen,Miljöbalken och kulturminneslagen (Adolfsson &amp; Boberg, 2015). Planområdet Trångforsen är utpekat i Bodens kommuns översiktsplan 2025 som ett utvecklingsområde för bebyggelse. Bodens kommuns mål är att öka till 30000 invånare till 2025, för att nå det målet arbetar kommunen aktivt med att stärka planberedskapen och på så sett kunna erbjuda attraktiva tomter. Planområdet Trångforsen består till störst del av naturmark och ligger i anslutning till Luleälven i öst. Närområdet består av kvartersmark med villabebyggelse och närmaste vägnätet är Kanalvägen i väst och Trångforsvägen i norr, delar av planområdet har tidigare använts för fotbollsverksamhet och utgörs därför av fotbollsplaner i naturgräs. Parallellt med planområdet ligger intill Engelska kanalen som är av riksintresse för kulturmiljövården, riksintresset är ett skyddat område som tar anspråk på stora delar av det tänkta planområdet. Intervju och platsbesök har utförts tillsammans med Länsstyrelsen angående hur hänsyn ska tas till Engelska kanalen i en framtida exploatering. Länsstyrelsen anser att ett avstånd på ca 10 meter från Engelska kanalen till planområdet ska tas för att bevara kanalhistorian. Utredningen visar på att planområdet är lämpligt att utvecklas till ett bostadsområde, detaljplanen för planområdet Trångforsen omfattar 27 fastigheter på ca 1200kvm vardera med en maximal byggnadsarea på 250kvm. I samband med den nya detaljplanen kommer strandskyddet att upphöra, planförslaget medger en gång -och cykelväg parallellt med älven, på så sätt kommer området närmast älven vara mer tillgängligt än idag