The location of a mobile station (MS) in a cellular network can be estimated using received signal strength (RSS) measurements that are available from control channels of nearby base stations. Most of the recent RSS-based location estimation methods that are available in the literature rely on the rather unrealistic assumption that signal propagation characteristics are known and independent of time variations and the environment. In this paper, we propose an RSS-based location estimation technique, so-called multiple path loss exponent algorithm (RSS-MPLE), which jointly estimates the propagation parameters and the MS position. The RSS-MPLE method incorporates antenna radiation pattern information into the signal model and determines the maximum likelihood estimate of unknown parameters by employing the Levenberg-Marquardt method. The accuracy of the proposed method is further examined by deriving the Cramer-Rao bound. The performance of the RSS-MPLE algorithm is evaluated for various scenarios via simulation results which confirm that the proposed scheme provides a practical position estimator that is not only accurate but also robust against the variations in the signal propagation characteristics.

An effective way for the joint detection and localization of multiple RF transmitters in a multipath environment is to enumerate the number of paths using the minimum-description-length information-theoretic algorithm, and to then measure the angle of arrival of each path, using an antenna array with a high-resolution direction-finding algorithm, such as MUSIC. The possible propagation paths are the angles corresponding to the peaks of the MUSIC pseudo-spectrum. Since more than one path may correspond to a single emitter source, further processing is required. The time-domain signals incident from these paths are then extracted with beamnforming techniques, such as minimum variance, in order to estimate their coefficients of correlation with each other. These correlation coefficients are used to decide whether or not these paths correspond to the same emitter. Among the paths that appear to originate from the same source, the path with the time signal that contains the highest power is selected as the original path of the source. Hence, the number of emitters and their angles of arrival are jointly estimated. A performance analysis of the method is presented via real-time laboratory experimentation and discussed in this paper. To demonstrate the effectiveness of the proposed technique, experimental results with two uncorrelated sources were compared to experimental results with a single source and a reflector. All of the experiments were conducted in an anechoic test chamber.

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Ozetce qagrilarin (155 Polis Imdat, 112 Acil Servis, v.b.) konum tespiti, orman yangininin ba*langiq noktasinin erken tespiti, deprem Bu bildiride iletil en sinyalmnkaii yiiren (TOA) Gauss-erken uyari sistemleri, hedef takibi, hasta veya 6ziirlii insanizge kestirim yontemi olan FLOM-MUSICk yaniikek iriniiiik larin ya da qocuklarin kontrol altinda tutulmasi gibi uygulaizgeckestirimoymentemi olaICnerFlm-MUSIC,nir kesirli kadar malarin hepsinde konumlandirma sistemlerine ihtiya, vardir. dereceli momentli MUSIC osnerilmektediri Her ne kadar Kiiresel Konumlandirma Sistemi (Global Positioning System godeirolt da dmiin gaussraltmi ok gen eribir o ltamlardaGausil -GPS) giiniumiizde en ,ok bilinen ve kullanilan konum tespit mdeglimi oeelsadadiirini gaybrtmektedieren olrltamlarndaGauss sistemi olmakla beraber bazi i ortamlarda, karma*ik ve yogun da~hmigeerlliinikabetekedi. iiriliinindiit* yapilarin oldugu yerlerde ye deniz altinda ,cah1,maz. 6zelligini yuiksek dogrulukla modelleyen ae-kararli dagilimi aiai luuyred v ei lid aimz zesasialinarak y taksekaoruluk* Modelleyen u-aa l mdam Iletilen sinyalin vari* siuresi (Time-of-Arrival -TOA) bir,ok esas alinarak tasarlanmi,s FLOM-MUSIC, bu uygulamada, ileti.im kanali diirtii yanitinin tepeciklerinin kestiriminde kul-konumlandirma sistemi tarafindan (GPS, GSM, v.b.) alici ile lanilmaktadir. ilk ...iilen tepecigin g6ril* hatti iizerinden verici arasindaki mesafenin kestirilmesi icin kullanilir. Teorik (LOS) geldigi varsayilir ye bu tepecigin 65liilen gecikmesi olarak konumu bilinmeyen bir nokta ile konumu belli iiu TOA'nin kestirim degeri olarak seilir. Benzetim sonu.lari nokta arasindaki mesafe ol,iilebiliyorsa o noktanin konumu yardimiyla, i * ortamlara ait radyo kanalindaki uokyollu ii,genleme yontemi ile kolayca kestirilebilir. sinyal ve diirtiun giuriiltii ortaminda FLOM-MUSIC'in ge-Ozellikle alici ile verici arasindaki uzakliktan faydalaleneksel ikinci-dereceden istatistige dayali MUSIC yani SOS-narak konum tespiti yapan yontemlerde dogru konumlandirma MUSIC'ten daha iyi kestirim sonucu verdigi g6sterilmi,tir. i,in ortamin dogru olarak modellenmesi gerekir. Bu makalede ortamdaki giiriultiu sinyallerinin kestirici dogruluguna etkisi Abstract uizerinde durulacaktir. Cogu sinyal isleme uygulamalarinda, ortamdaki giuriiltii Gauss dagilimli olarak kabul edilmi,tir. FLOM-MUSIC (Fractional Lower Order Moment-MUSIC), a Hlui o aalraypln~l~aad radk high resolution spectral estimation algorithm, is proposed for grltii siny a nlerininapilanun atam molara a daki TOA (Time of Arrival) estimation under non-Gaussian noise. g .5stertdi sin -kaarlindn ilo mailestileogarak lGanss daha While Gaussianity is the conventional model in statistical sig-gdogru modellenebilecegi gdsterilmi,stir [1]. Bu g allnmada danal processing, it does not accurately represent noise with im-kara dellimacsa i glstvrilandirtiin g t alinda pulsive nature that do occur in some wireless environments. k estirimi sahnFlO uSI yiln dnerilmil yetge-FLOM-MUSIC is, in particular, designed for the a-stable leneTOA kestirimi iyc...

OzetBu çalışmada, hücresel cep telefonlarının konum tespitinde varış zamanı (time-of-arrival TOA)ölçümlerinde meydana gelen kesintili hat (non-line of sight-NLOS) kaynaklı hataların azaltılması için bir yöntemönerilmektedir. Ilk aşamada her baz istasyonu (BS) -mobil istasyonu (MS) kombinasyonuna ait TOAölçüm dizileri LOS veya NLOS olarak sınıflandırılıyor, bu sınıflandırmaya göre farklı Kalman filtreleriyle zamanda düzeltiliyor. Sonra birçok BS ve bir MS için elde edilen zaman dizileri agırlıklandırmalı kısıtlı en küçük kareler yöntemi (constrained weighted least squares CWLS) ile birleştirilerek MS'in konum bilgisi elde ediliyor. Simülasyon sonuçlarıönerilen yöntemin yararını göstermektedir. AbstractA method to mitigate the effects of non-line-of-sight (NLOS) errors in time-of-arrival (TOA) based cellular positioning is proposed. TOA readings are initially classified as LOS or NLOS and Kalman filtered for each base station (BS)-mobile station (MS) combination. After Kalman tracking the TOA / range sequences, range information for multiple BS's and one MS is converted to the MS's position information through a constrained weighted least squares technique (CWLS). Simulation results demonstrate the utility of the proposed algorithm.