Iterative amplitude/phase multiple-symbol differential sphere detection for DAPSK modulated transmissions

Differentially encoded and non-coherently detected transceivers exhibit a low complexity, since they dispense with complex channel estimation. Albeit this is achieved at the cost of requiring an increased transmit power, they are particularly beneficial, for example in cooperative communication scenarios, where the employment of channel estimation for all the mobile-to-mobile links may become unrealistic. In pursuit of high bandwidth efficiency, differential amplitude and phase shift keying (DAPSK) was devised using constellations of multiple concentric rings. In order to increase resilience against the typical high-Doppler-induced performance degradation of DAPSK and/or enhance the maximum achievable error-free transmission rate for DAPSK modulated systems, multiple-symbol differential detection (MSDD) may be invoked. However, the complexity of the maximum-a-posteriori (MAP) MSDD increases exponentially with the detection window size and hence may become excessive upon increasing the window size, especially in the context of iterative detection aided channel coded system. In order to circumvent this excessive complexity, we conceive a decomposed two-stage iterative amplitude and phase (A/P) detection framework, where the challenge of having a non-constant-modulus constellation is tackled with the aid of a specifically designed information exchange between the independent A/P detection stages, thus allowing the incorporation of reduced-complexity sphere detection (SD). Consequently, a near-MAP-MSDD performance can be achieved at a significantly reduced complexity, which may be five orders of magnitude lower than that imposed by the traditional MAP-MSDD in the 16-DAPSK scenario considered

Minimum error probability MIMO-aided relaying: multihop, parallel, and cognitive designs

A design methodology based on the minimum error probability (MEP) framework is proposed for a nonregenerative multiple-input multiple-output (MIMO) relayaided system. We consider the associated cognitive, the parallel and the multi-hop source-relay-destination (SRD) link design based on this MEP framework, including the transmit precoder, the amplify-and-forward (AF) relay matrix and the receiver equalizer matrix of our system. It has been shown in the literature that MEP based communication systems are capable of improving the error probability of other linear counterparts. Our simulation results demonstrate that the proposed scheme indeed achieves a significant BER reduction over the existing linear schemes

Брэгговское отражение световых волн от сверхрешеток вблизи экситонных резонансов

A real-time cooperative localization system,utilizing dual foot-mounted low-cost inertial sensors and RFbasedinter-agent ranging, has been developed. Scenario-basedtests have been performed, using fully-equipped firefightersmimicking a search operation in a partly smoke-filledenvironment, to evaluate the performance of the TOR (TacticallOcatoR) system. The performed tests included realisticfirefighter movements and inter-agent distances, factors that arecrucial in order to provide realistic evaluations of the expectedperformance in real-world operations. The tests indicate that theTOR system may be able to provide a position accuracy ofapproximately two to three meters during realistic firefighteroperations, with only two smoke diving firefighters and onesupervising firefighter within range.QC 20140619</p

Spatial modulation aided zero-padded single carrier transmission for dispersive channels

In this paper, we consider spatial modulation (SM) operating in a frequency-selective single-carrier (SC) communication scenario and propose zero-padding instead of the cyclic-prefix considered in the existing literature. We show that the zero-padded single-carrier (ZP-SC) SM system offers full multi-path diversity under maximum-likelihood (ML) detection, unlike the cyclic-prefix based SM system. Furthermore, we show that the order of ML detection complexity in our proposed ZP-SC SM system is independent of the frame length and depends only on the number of multipath links between the transmitter and the receiver. Thus, we show that the zero-padding applied in the SC SM system has two advantages over the cyclic prefix: 1) achieves full multipath diversity, and 2) imposes a relatively low ML detection complexity. Furthermore, we extend the partial interference cancellation receiver (PIC-R) proposed by Guo and Xia for the detection of space-time block codes (STBCs) in order to convert the ZP-SC system into a set of narrowband subsystems experiencing flat-fading. We show that full rank STBC transmissions over these subsystems achieves full transmit, receive as well as multipath diversity for the PIC-R. Furthermore, we show that the ZP-SC SM system achieves receive and multi-path diversity for the PIC-R at a detection complexity order which is the same as that of the SM system in flat-fading scenario. Our simulation results demonstrate that the symbol error ratio performance of the proposed linear receiver for the ZP-SC SM system is significantly better than that of the SM in cyclic prefix based orthogonal frequency division multiplexing as well as of the SM in the cyclic-prefixed and zero-padded single carrier systems relying on zero-forcing/minimum mean-squared error equalizer based receivers

Parameter Estimation using a Sensor Array in a Ricean Fading Channel

The estimation of the Direction Of Arrival (DOA) and the variance of the angular spread, using an array of sensors in the case of a Ricean channel is considered, using the Maximum-Likelihood, Least-Squares and Weighted Least Squares criteria. The Cram&apos;er-Rao bound is also obtained for the problem of interest. Simplification of the cost functions to reduce the dimension of the problem has been carried out and the performance of the methods has been studied based on numerical experiments. 1 Introduction The use of sensor arrays in the field of Mobile Communication to improve the performance of a cellular system has been an active area of research recently. An important issue is to efficiently use the available channel bandwidth to provide services to as many users as possible. Techniques using an array of sensors have been proposed which estimate the Direction-Of-Arrival (DOA) of the received signal from a mobile unit and the associated angular spread due to scattering, to form multiple..

Incidence of essential hypertension in young adult males followed for over two decades

Background: The data about the incidence of hypertension in India is scarce and is lacking about hypertension in young adult patients. We studied the incidence of hypertension in a cohort of young adult male military personnel followed for a long duration. Methods: The data for this retrospective, observational study was derived from the electronic medical records (EMR) of the male service personnel enrolled between 1990 and 2015. All subjects were recruited before 18 years of age in good health without any disease. Hypertension in young adults was defined as the onset of the disease prior to 45 years of age. We calculated the incidence rates as per person years using appropriate statistical methods. Results: Our study population includes 51,217 participants (median age 33 years, range 17–54) with a mean follow up of 12.5 years, giving a total observation period of 613,925 person-years (py). During the study period, 360 patients developed hypertension, giving an incidence rate of 58.6 per 100,000 py (95% CI 52.8–64.9). The mean age at the time of diagnosis was 33.5 ± 5.7 years (range 20–45) with 5.6 ± 3.9 years (range 0.3–21 yr) of follow up after the diagnosis. Only 16 patients (4.4%) had associated cardiovascular complications attributable to hypertension. Conclusion: Our cohort had low incidence rates of hypertension when compared with other studies from abroad. Active military service may offer protection from the hypertension and associated complications. Keywords: Epidemiology, Prevalence, Hypertension, Prehypertensio

A trigger-happy soldier with bilateral ptosis and dysphagia

Muscular dystrophy encompasses a group of disorders characterized by the progressive weakness of the skeletal muscles. These disorders are mostly inherited and have characteristic age and muscle group predilection. Lingual muscle involvement is an unusual feature in patients with the muscular dystrophy and helps in the differential diagnosis. We recently encountered a serving soldier presenting with complaints of bilateral ptosis and dysphagia of 5 years duration. Examination showed bilateral ptosis, percussion myotonia, generalized muscular atrophy including that of tongue muscles, and a characteristic hatchet facies. Investigations revealed elevated creatine kinase and myotonic discharges on electromyography leading to a diagnosis of myotonic dystrophy type 1. Muscular dystrophy has a varied presentation and can pose a diagnostic problem in clinical practice. We present the case to highlight the differential diagnosis of tongue atrophy in patients with muscular dystrophy