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In this paper, we study the design of linear dispersion codes (LDCs) for asynchronous cooperative communication networks. Firstly, the concept of conventional LDCs is extended to the delay-tolerant version and new design criteria are discussed. Then we propose a new design method to yield delay-tolerant LDCs that approach near-optimal capacity as well as minimum average pairwise error probability...
In mobile Ad-hoc networks forwarding data through intermediate relays extends the coverage area and enhances the network throughput. Dynamic assignment of routes for data transmission from sources to destinations that is optimized based on channel conditions in a cross-layer manner could provide improved performance. We consider a general multiuser two-hop transmission, where each flow is subject...
In this paper, we investigate the outage performance of a dual-hop relaying systems with partial relay selection and feedback delay. The analysis considers the case of Rayleigh fading channels when the relaying station as well as the destination undergo mutually independent interfering signals. Particularly, we derive the cumulative distribution function (c.d.f.) of a new type of random variable involving...
The impact of outdated channel state information (CSI) on the performance of variable-rate adaptive M-ary quadrature amplitude modulation (M-QAM) in an amplify-and-forward (AF) opportunistic relaying system over Rayleigh fading channels is analyzed. Closed-form expressions are derived for the average spectral efficiency, outage probability and the average bit error rate under outdated CSI. Using numerical...
The latest wireless communication systems focus on developing MIMO-OFDM systems that allow the transmission of very high data rates in fading environments. We can optimize these systems even further by setting the modulation and coding adaptively according to the channel conditions, and by using sub-carrier frequency and power allocation techniques. The overall system performance depends on the accuracy...
The stochastic resonance in a time-delayed Logistic growth model subject to correlated multiplicative and additive white noise as well as to multiplicative periodic signal is investigated. Using small time delay approximation, we get the expression of the signal-to-noise ratio (SNR). It is found that the SNR is a non-monotonic function of the delayed times, of the system parameters, of the intensities...
This paper introduces a silicon-based imaging array for remote measurements of complex permittivity of tissue. Using a coherent pulsed measurement approach, this time-frequency resolved technique recovers the three dimensional mapping of electrical properties of the subject in the microwave/millimeter-wave frequency spectrum. Some of the major challenges in the design of the system are described....
This paper describes improvements to the technique of velocity selective recording (VSR) in which multiple neural signals are matched and summed to identify excited axon populations in terms of velocity. This form of recording has been termed intrinsic velocity selective recording (IVSR). The signals are acquired using a multi-electrode cuff (MEC) which is now available as a component for use in implantable...
In order for interference alignment (IA) techniques to be implemented in future generation mobile multiple-input multipleoutput (MIMO) communications systems, they must be shown to be robust to system limitations such as quantisation and delay. Current IA algorithms in the literature assume global and instantaneous channel knowledge. In this paper, a novel IA algorithm is proposed which uses limited...
The PARIS in orbit demonstrator is a novel altimeter concept recently proposed by the European Space Agency with has the objective of observing ocean mesoscale features with an expected sea surface height estimation accuracy of about 20 cm and unprecedented simultaneous spatial-temporal sampling of the ocean. This altimeter is based on the well known PARIS (also defined as GNSS-R) technique, which...
Adaptive filtering (AF) acquisition scheme has been proved to be an effective pseudo-noise (PN) code acquisition in DS-SS system, which is especially useful to long PN code acquisition in low Signal Noise Ratio (SNR) environment [1]. In order to make use of this scheme in those PN code acquisition systems with data modulation, a modified adaptive filtering method is proposed in this paper, where the...
The Global Positioning System (GPS) is widely used for many applications but its performance can be impacted significantly by the environment. This can be overcome to a large extend by processing the signal in space and time. The space processing is achieved with a seven element planar array followed by an algorithm to calculate the antenna weights in such a way that the interferences can be nulled...
A method that virtually double the oversampling ration of a second order sigma-delta (ΣΔ) modulator is described. Accounting for a limited cost, the resolution increases by about 2-bit and power just increases by few percents. Therefore, the FoM diminishes by a factor close to 3.5. Simulation at the behavioral level of the proposed method verifies the operation. Circuit level schemes indicates that...
It can be concluded that an upper bound has been found for the SNR of the signals at the PARIS-IOD if one-bit quantization is used and a linear cross-correlation with the same shape as the analog correlation is desired. That is, it is not possible to increase the signal SNR at any desired level without distorting the cross-correlation waveform if one-bit digitalization is used. Simulation results...
The work described in this paper proposes two Smart Hybrid-Automatic Repeat Request (SHARQ) schemes with incremental redundancy, that are developed for a dual-hop network of two relays implementing cooperative communication. In a dual-hop network consisting of multiple relays, one of the most challenging tasks is to determine an appropriate trade-off point between the end-to-end block-error rate (BLER)...
In this paper, we study the impact of an important RF impairment inside direct-conversion receiver, namely the I/Q imbalance, on the performance of OFDM radio link over frequency-selective Rayleigh fading channel. Closed-form expressions for link performance, in terms of detection error rate, ergodic capacity and outage capacity, under both frequency-selective RX I/Q imbalance and noisy frequency-selective...
The ultimate goal of this work is to identify a methodical analysis of imager design to achieve high level of flexibility and modularity. It will enable early stages of design space exploration using hierarchical approach. In particular, we develop generic models for imager IC in order to explore early design choices throughout the hierarchy. This modeling approach supports top-down design flows.
This paper presents a novel acquisition method for time-variant channels, which yield a different channel phasor for each transmission symbol due to the non-zero Doppler frequency. The alternating channel phasors prevent a coherent symbol averaging and require an incoherent or a differentially-coherent symbol averaging instead. Compared to the incoherent symbol averaging, the differentially-coherent...
This paper presents a self-injection-locked (SIL) sensor array for cancelling the effects of random body movement on the detection of vital signs. To achieve this goal, a subject is seated between two SIL sensors to measure rates of respiration and heartbeat using the Doppler shift, and the effects of random movements by the subject are cancelled by wireless mutual injection locking (MIL) of the two...
In this paper we investigate the issue of exploiting switched beamforming antennas to improve multicast transmission in wireless networks. Under the practical assumptions that different beams may have arbitrary overlapping patterns and that each user can receive data at different rates under different beams, we formulate the problem as minimizing the total multicast delay subject to the constraint...
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