Phase Jitter Modeling for Uplink OFDMA

Multicarrier (MC) systems, such as OFDMA (Orthogonal Frequency Division Multiple Access), which are quite developed in the literature, were shown to be the adequate solution for multipath transmission. However, even with these systems, synchronization errors can't be avoided. In this contribution we study the sensitivity of uplink OFDMA system to the phase jitter for both models proposed : the gaussian and the rayleigh models. By investigating the performance degradation of the OFDMA system, we point out that, first, the degradation depends, not only, on the phase jitter variance, but also, on the jitter power density function, and then, the rayleigh model gives better performance regarding the SNR degradation

EVM as generic QoS trigger for heterogeneous wieless overlay network

Fourth Generation (4G) Wireless System will integrate heterogeneous wireless overlay systems i.e. interworking of WLAN/ GSM/ CDMA/ WiMAX/ LTE/ etc with guaranteed Quality of Service (QoS) and Experience (QoE).QoS(E) vary from network to network and is application sensitive. User needs an optimal mobility solution while roaming in Overlaid wireless environment i.e. user could seamlessly transfer his session/ call to a best available network bearing guaranteed Quality of Experience. And If this Seamless transfer of session is executed between two networks having different access standards then it is called Vertical Handover (VHO). Contemporary VHO decision algorithms are based on generic QoS metrics viz. SNR, bandwidth, jitter, BER and delay. In this paper, Error Vector Magnitude (EVM) is proposed to be a generic QoS trigger for VHO execution. EVM is defined as the deviation of inphase/ quadrature (I/Q) values from ideal signal states and thus provides a measure of signal quality. In 4G Interoperable environment, OFDM is the leading Modulation scheme (more prone to multi-path fading). EVM (modulation error) properly characterises the wireless link/ channel for accurate VHO decision. EVM depends on the inherent transmission impairments viz. frequency offset, phase noise, non-linear-impairment, skewness etc. for a given wireless link. Paper provides an insight to the analytical aspect of EVM & measures EVM (%) for key management subframes like association/re-association/disassociation/ probe request/response frames. EVM relation is explored for different possible NAV-Network Allocation Vectors (frame duration). Finally EVM is compared with SNR, BER and investigation concludes EVM as a promising QoS trigger for OFDM based emerging wireless standards.Comment: 12 pages, 7 figures, IJWMN 2010 august issue vol. 2, no.

Sensitivity of Multi Carrier 2 Dimensional Spreading systems to carrier phase noise

5 pagesPhase noise is a topic of theoretical and practical interest in electronic circuits. Although progress has been made in the characterization of its description, there still considerable gaps in its effect especially on the multi carrier spreading systems. In this paper, we investigate the impact of a local oscillator phase noise on the multi carrier 2 dimensional spreading systems known as OFDM-CDMA. The contribution of this paper is twofold. First, we use some properties of random matrix and free probability theory to give a simplified expression of the Signal to Interference and Noise Ratio SINR obtained after equalization and despreading. The latter is independent of the actual value of the spreading codes of different users and depends principally on the complex amplitudes of the estimated channel coefficients. Second, we use this expression to derive new weighting functions which are very interesting for the RF engineers when they design the frequency synthesizer. Simulation results are provided to discuss and validate our model

A Non-Data-Aided and Non-Phase-Based AFC Method for MPSK DS/CDMA Transceivers Used in Digital Broadcasting

Due to its high-performance broadcast capability, M -ary phase-shift-keying (MPSK) direct sequence code division multiple access (DS/CDMA) technique is widely used in terrestrial and satellite communications to provide wired/wireless services such as audio broadcasting, video broadcasting and high-speed data transmission. However, both coherent and noncoherent MPSK modulation schemes are sensitive to the carrier frequency offset (CFO) incurred by transceiver oscillator instability and/or Doppler shift. In this paper, a nondata-aided and nonphase-based automatic frequency control (AFC) method for MPSK DS/CDMA transceivers is proposed. Different from phase-based AFC approaches, which utilize the frequency-offset-induced phase rotation and suffer from the modulo- 2π phase ambiguity, the proposed method exploits the frequency-offset-induced power degradation and has a wide tracking range of twice the symbol rate, which is independent of the phase keying number as well as the spreading code length. To shorten the tracking time of AFC, the improved steepest descent algorithm and the reshaped S curve are employed. Due to its wide tracking range, short tracking time and low implementation complexity, the proposed AFC method is attractive for terrestrial and satellite-based digital broadcasting.published_or_final_versio

Wavelet-based multi-carrier code division multiple access systems

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

On the System Level Prediction of Joint Time Frequency Spreading Systems with Carrier Phase Noise

TCOM-08-0122 (Index: A)International audiencePhase noise is a topic of theoretical and practical interest in electronic circuits. Although progress has been made in the characterization of its description, there are still considerable gaps in its effects especially on multi-carrier spreading systems. In this paper, we investigate the impact of a local oscillator phase noise on the multi-carrier 2 dimensional (2D) spreading systems based on a combination of orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA) and known as OFDM-CDMA. The contribution of this paper is multifold. First, we use some properties of random matrix and free probability theory to give a simplified expression of signal to interference and noise ratio (SINR) obtained after equalization and despreading. This expression is independent of the actual value of the spreading codes and depends mainly on the complex amplitudes of estimated channel coefficients. Secondly, we use this expression to derive new weighting functions which are very interesting for the radio frequency (RF) engineers when they design the frequency synthesizer. Therefore, based on these asymptotic results, we adapt a new method to predict the bit error rate (BER) at the output of the channel decoder by using an effective SINR value. We show by simulations the validity of our models and that at a given BER, the required signal to noise ratio (SNR) may easily increase due to the carrier phase noise

Array communications in wireless sensor networks

Imperial Users onl

Survey of End-to-End Mobile Network Measurement Testbeds, Tools, and Services

Mobile (cellular) networks enable innovation, but can also stifle it and lead to user frustration when network performance falls below expectations. As mobile networks become the predominant method of Internet access, developer, research, network operator, and regulatory communities have taken an increased interest in measuring end-to-end mobile network performance to, among other goals, minimize negative impact on application responsiveness. In this survey we examine current approaches to end-to-end mobile network performance measurement, diagnosis, and application prototyping. We compare available tools and their shortcomings with respect to the needs of researchers, developers, regulators, and the public. We intend for this survey to provide a comprehensive view of currently active efforts and some auspicious directions for future work in mobile network measurement and mobile application performance evaluation.Comment: Submitted to IEEE Communications Surveys and Tutorials. arXiv does not format the URL references correctly. For a correctly formatted version of this paper go to http://www.cs.montana.edu/mwittie/publications/Goel14Survey.pd