We focus on the Multi-Rate Sampling (MRS) Compressed Sensing (CS) scheme, in which several Analog-to-Digital Converters (ADC) sample in parallel at different sub-Nyquist rates. In this paper, we postulate that a good signal recovery requires the measurement matrix rank (MMR) to be as high as possible. We also present an upper-bound for the MMR. Choosing pairwise coprime sampling rates allows to reach this upper-bound.

This paper studies the Cramér-Rao bound (CRB) for burst-mode transmission synchronization of Single-Sideband Frequency Shift Keying (SSB-FSK). Based on the CRB computations of burst-mode CPM, for conventional double sided schemes, it was shown that it is possible to obtain an optimum training sequence that minimizes the CRBs simultaneously for the joint estimation of symbol timing, frequency offset, and carrier phase. However, due to the SSB-FSK non-antipodal alphabet, it is impossible to use the same optimum sequence to minimize the CRBs for all parameters simultaneously. Meanwhile, in this paper, we propose a new general training sequence that can minimize the sum of all CRBs for any binary SSB-FSK. The derived results can be helpful for data-aided (DA) synchronization of SSB-FSK modulation.

When an unknown signal propagates through an AWGN channel of unknown variance, estimating the noise variance can be difficult. We propose a novel method to perform blind noise variance estimation, based on the separation of noise-only values and signal-plus-noise values in the frequency representation of the received signal. This separation is conducted using the K-means algorithm. Our linear-complexity method is efficient and accurate, requires a limited amount of samples and is robust to SNRs as low as -7 dB. It relies on two weak hypotheses of compacity and sparsity on the signal of interest.

The standard multiple-input multiple-output (MIMO) detectors exploit the available information to resolve the detection problem. Alternative algorithms, such as bioinspired or geometrical detectors, mix exploitation with exploration to bypass local minima and enhance the results. This paper examines the benefits of adding exploration to the traditional tree-based detectors. For this purpose, a new interpretation of the bio-inspired detector based on the firefly algorithm (FA) is proposed. It is studied in a tree search paradigm and extended to soft-outputs. The findings suggest that the addition of a stochastic exploration to tree-based detectors significantly improves performance with a small computational overhead.

This study revokes the performance of continuous phase modulation (CPM) able to generate a single-sideband (SSB) spectrum directly. This signal is analyzed in terms of modulation indices, pulse lengths, and pulse widths, all of which affect error probability, bandwidth, SSB property, and receiver complexity. The error probability performance is based on an approximation of the minimum Euclidean distance. A numerical power spectral density calculation for this particular SSB modulation in terms of the modulation index is presented. Reasonable tradeoffs in designing modulation schemes have been proposed using multi-objective optimization to ensure sizable improvements in bit error rate (BER), spectral efficiencies, and complexity without losing the property of being a SSB signal. Performance comparisons are made with known CPM schemes, e.g., Gaussian Minimum Shift Keying (GMSK) and Raised Cosine based CPM (RC).

In this article, we address the problem of optimal joint power and resource allocation when Non-Orthogonal Multiple Access (NOMA) and Orthogonal Frequency Multiple Access (OFDMA) are combined for a hybrid downlink multiple access. First, an optimal solution of joint power and resource allocation minimizing the transmit power consumption, is obtained by rewriting the original optimization problem into an equivalent convex one and then by solving it by means of the well-known interior-point method. Second, we analyze the properties of the optimum, which are twofold; we show that at the optimum, the order of the users is preserved from one channel to another. Then, we derive a closed-form expression for the optimal power allocation in the particular case where all users have positive non-zero transmit powers in all channels.

In this study, the authors consider the utilisation of multicast technology in cellular networks given different arrival patterns for the content requests of mobile users. Traditionally, the performance evaluation of multicast in the literature usually depends on the adoption of temporal Poisson processes for content requests, which is not accurate any more according to many real data measurements. Therefore, to make use of the bursty nature of content requests, they propose a hybrid unicast/multicast strategy where the base station (BS) can perform the unicast or multicast procedure according to its serving status. By modelling the complete process into a circular Markov chain, they derive the average latency of content requests and the average power consumption of BSs under different arrival patterns and serving configurations in theoretical and/or simulative ways. Moreover, the multicast threshold introduced in their strategy can be dynamically adjusted to achieve a joint optimisation between average latency and power consumption when confronted with varied demands. Numerous results show that the proposed strategy can not only reduce the average latency of content requests but also decrease the average power consumption of BSs, especially under the bursty request arrival patterns.

In this paper, a new Peak-to-Average Power Ratio (PAPR) reduction technique, called Adaptive Width Peak Cancellation (AWPC), for multicarrier systems is proposed. The principle of this technique is to control the peak cancellation pulse width, according to the width of each peak of the original signal. Secondly, we propose to combine the AWPC and the clipping techniques where an interesting improvement is noticed. These proposed techniques outperform the conventional Peak Cancellation (PC) technique which use only one pulse width for all peaks whatever the signal peak width. Numerical results show that a better PAPR reduction gain is reached while less EVM distortion is introduced.

The pulse amplitude modulation (PAM) decomposition of continuous phase modulation (CPM) signals has been recently revamped to give another view of ternary shaped offset quadrature phase shift keying (SOQPSK) signals as duobinary CPMs. Taking advantage of this approach, we propose a new maximum likelihood sequence estimation (MLSE) OQPSK trellis-type detector which relies on the presence of a single main pulse unlike the detectors developed by Kaleh and Perrins. We show that the proposed solution has the best bit error rate (BER) performance/complexity trade-off among the state of the art detectors and we endorse by these results that SOQPSK modulation can be approximated as a linear modulation.

The distribution of the peak-to-average power ratio (PAPR) of multicarrier systems is studied in the context of signals featuring low subcarriers number. Considering the mean power of the signal as a random variable, a general cumulative distribution function of the PAPR is suggested. We show that the new formulation is valid not only for low subcarriers number but also for larger subcarriers number. Thus, an asymptotic analysis using a large subcarriers number proves a perfect concordance between the suggested approach and the state-of-the-art derivations only valid for large subcarriers number. All the theoretical developments are supported through simulations, and we discuss the case of oversampled signals as well.

The aim of this paper is to analytically evaluate the spectral regrowth at the output of a transmitter due to the nonlinear components such as the power amplifier (PA). Therefore, we propose a generalization of existing closed-form expression for the Power Spectral Density (PSD) of nonlinear amplified multicarrier signals to be valid for any type of modulation. Then, we derive the PSD of the amplified multicarrier signal taking into account the predistortion technique. To the best of our knowledge, no analytical PSD expression of the transmitted signal taking into account the predistortion technique exists in the literature. Such analytical expression could be of particular interest to those involved in the design of cellular communications systems. In fact, this analytical expression is very useful to determine the optimal configuration of the PA and the predistortion technique that allows to obtain the maximum PA efficiency while satisfying the linearity requirements.

In this study, the authors consider the standard condition number (SCN) detector for a cognitive radio with finite number of cooperative sensors. They derive an exact nested form of the distribution of the SCN for the central uncorrelated, non‐central uncorrelated and central semi‐correlated Wishart matrices under and hypotheses. Due to the complexity of these expressions, the authors approximate the distribution of the SCN by the generalised extreme value distribution using moment matching. They derive the exact form of the p th moment of the SCN for these cases. Consequently, the performance probabilities are approximated and a simple decision threshold formula is provided. In addition, a similar approximation for the detection probability is provided using non‐central/central approximation. They show that the proposed analytical approximations provide high accuracy using Monte‐Carlo simulations.

Linear minimum mean square error (LMMSE) is by definition the optimal channel estimator in the sense of mean square error criterion, but its practical application is limited by its high complexity. Furthermore, the LMMSE estimation method requires the knowledge of both the channel and the noise statistics, which are a priori unknown at the receiver. A wide range of techniques are proposed in the literature in order to overcome these two drawbacks. In this study, the authors give an overview of the LMMSE‐based channel estimation in an orthogonal frequency division multiplexing (OFDM) context. A didactic reminder concerning the basics of LMMSE estimation and its performance is provided, and a survey of techniques of the literature, which enable the practical application of LMMSE and the reduction of its complexity, is presented in both single‐input single‐output and multiple‐input multiple‐output contexts. Finally, some perspectives are provided, in particular the application of the LMMSE estimator to flexible waveforms beyond OFDM.

In this paper, we investigate the pulse amplitude modulation (PAM) decomposition and the spectral efficiency of duobinary continuous phase modulation (CPM), where duo- binary CPM represents a ternary CPM whose symbols are generated using a duobinary encoder. We show that this precoder ensures a higher spectral efficiency compared with binary CPM and we propose a PAM decomposition characterized by the presence of a single main pulse and by uncorrelated pseudo-symbols for a half integer modulation index value for this ternary CPM. We show that shaped offset quadrature phase shift keying belongs to this CPM family and we provide a new reduced complexity trellis detector capable of reaching identical performance as the one introduced by Perrins as well as new linear detectors.

The topology of smallcell Base Stations (BS) in wireless networks, serving as a basis of networking performance analysis was subject to lots of investigations around Poisson Cluster Process (PCP) theory due to the smallcells pairwise interaction within hot areas (shopping centre, office...). This paper aims at establishing through a detailed comparison the spatial points pattern fitting the best with BSs real deployment data, for different frequency ranges and different operators. The candidate models belong to the Neyman-Scott Process (NSP) and results show that the NSP with variance gamma kernel is the most accurate for matching the microcells distribution for different scenarios.

This study deals with a bit error rate (BER) floor performance analysis for orthogonal frequency division multiplexing (OFDM) systems using pilot‐aided channel estimation with polynomial interpolations. Such a performance analysis has been previously undertaken in the literature, but is limited to binary phase shift keying and 4‐quadrature amplitude modulation (4‐QAM) constellations. The main contribution of this study is then to analyse the BER floor achieved by a 16‐QAM OFDM signal in a Rayleigh channel. To achieve this, the binary error probability is obtained by carrying out the analysis on maximum significant bits (MSB) and least significant bits (LSB). The MSB leads to the similar results as those obtained in 4‐QAM, but very specific developments are required to obtain the error probability of the LSB. Numerical results show that the proposed BER performance analysis is valid for the 16‐QAM constellation.

With the growing number of cores on chips, conventional electrical interconnects reach scalability limits, leading the way for alternatives like Radio Frequency (RF), optical and 3D. Due to the variability of applications, communication needs change over time and across regions of the chip. To address these issues, a dynamically reconfigurable Network on Chip (NoC) is proposed. It uses RF and Orthogonal Frequency Division Multiple Access (OFDMA) to create communication channels whose allocation allows dynamic reconfiguration. We describe the NoC architecture and the distributed mechanism of dynamic allocation. We study the feasibility of the NoC based on state of the art components and analyze its performances. Static analysis shows that, for point to point communications, its latency is comparable with a 256-node electrical mesh and becomes lower for wider networks. A major feature of this architecture is its broadcast capacity. The RF~NoC becomes faster with 32 nodes, achieving a x3 speedup with 1024. Under realistic traffic models, its dynamic reconfigurability provides up to x6 lower latency while ensuring fairness.

This paper presents a preamble-based linear minimum mean square error (LMMSE) estimation technique for filter bank multicarrier (FBMC) modulations. Orthogonal frequency division multiplex (OFDM) systems have been extensively used in digital communication systems, for they are extremely efficient in terms of channel estimation and equalization. Estimation being a crucial part of digital communication systems, techniques have been developed to reduce the impact of noise on the channel estimation process, the optimal one being the LMMSE one. Until recently, non-orthogonal multicarrier modulations such as FBMC, were unable to use OFDM-like estimation techniques due to the non-orthogonality. The interference approximation method (IAM) is one of the most popular method among preamblebased estimation techniques with a limited complexity. This paper present a combination of IAM and a LMMSE-based algorithm that makes possible to achieve a LMMSE estimation in FBMC.

Orthogonal Frequency Division Multiplexing (OFDM) systems are extremely sensitive to nonlinear distortions brought by the Power Amplifier (PA) because of the inherent high peak-to-average power ratio (PAPR) of the signal. In this paper, we analyze the impact of the non-linearities on the output signal, assuming that the transmitter is equipped with a linearization stage before the PA. Therefore, the expression of the Error Vector Magnitude (EVM) of the output signal is analytically derived with or without the use of the linearization process. We provide analytical expressions of the EVM in the form of a series expansion that depends on the transition factors of the PA and predistortion characteristics. Simulations results confirm the accuracy of our analytical expressions, even when limiting the series expansion to an order of 4.

In this paper, the authors provide an analytical expression of the mean square error (MSE) and the bit error rate (BER) lower bound of an orthogonal frequency division multiplexing signal transmission over a multipath Rayleigh channel considering estimation errors. For some pilot arrangements, an interpolation is required to perform the channel estimation. Owing to their low complexity, polynomial based interpolations are usually applied at the receiver, which induces estimation and signal errors. Based on a statistical analysis of these errors, the exact MSE expression of the channel estimation is provided. Furthermore, with a geometrical study of the constellation, an analytical BER limit is derived. For a given channel, it is shown that the errors are perfectly characterised by the interpolation method and the frequency gap between the pilot tones. All the steps of the analytical developments are validated through simulations. The proposed analysis then predicts the performance of the receiver, thus enabling the latter to a priori select the interpolation method with minimum complexity, according to a given channel and a BER target.

This paper deals with the minimum mean square error (MMSE)-based multipath channel and noise variance estimation in the case of a pilot-aided orthogonal frequency division multiplexing/offset quadrature amplitude modulation (OFDM/OQAM) system. The theoretical expression of the LMMSE channel estimation is formulated and a simpler closed-form is derived. The MSE analysis shows that LMMSE inevitably reaches an error floor due to the interference inherent to OFDM/OQAM modulation. Furthermore, an algorithm for the joint MMSE estimation of both the channel and the noise variance (J-MCNE) is proposed and features a reduced complexity thanks to the low-rank approximation method. The noise level estimation represents a challenge as it is concealed in the intrinsic interferences generated by the OFDM/OQAM. Simulations reveal the capability of the proposed J-MCNE method to estimate the noise variance and show that the achieved bit error rate (BER) is close to that of the perfect estimation.

This paper introduces flexible radio techniques inside integrated circuits in order to tackle the interconnect issue for many-core chips. We propose to take benefits from OFDMA for a RF-interconnect associated to a carrier allocation policy and adaptive modulation. A 20 GHz bandwidth is shared between 32 tile sets made of 32 tiles of 4 cores each, for a 4096 cores chip. We adopt a cognitive radio approach in order to dynamically share 1024 carriers, which avoids inter-cluster communication contention and decreases latency compared to conventional static approaches.

A paradigm shift is apparent in Chip Multiprocessor (CMP) design, as the new performance bottleneck is becoming communication rather than computation. It is widely provisioned that number of cores on a single chip will reach thousands in a decade. Thus, new high rate interconnects such as optical or RF have been proposed by various researchers. However, these interconnect structures fail to provide essential requirements of heterogeneous on-chip traffic; bandwidth reconfigurability and broadcast support with a low complex design. In this paper we investigate the feasibility of a new Orthogonal Frequency Division Multiple Access (OFDMA) RF interconnect for the first time to the best of our knowledge. In addition we provide a novel dynamic bandwidth arbitration and modulation order selection policy, that is designed regarding the bimodal on-chip packets. The proposed approach decreases the average latency up to 3.5 times compared to conventional static approach.

Digital predistortion (DPD) and Crest Factor Reduction (CFR) are applied separately in radio frequency power amplifiers (PAs) in general. This paper proposes a method to jointly optimize DPD and CFR. For a given model of predistorter our solution gives automatically the Peak to average power ratio (PAPR) reduction gain to be applied by the CFR module. Within the DPD module PAPRs of original input signal and PA output and PAPR at predistorter output without CFR are used to estimate an optimal CFR gain through mathematical calculations. The combined CFR/DPD module ensures that the PAPR at the output of predistorter will not exceed a given limit. Hence, the envelope clipping module which is typically present to protect the PA, may be removed. In addition the proposed method offers a higher operating range of the DPD while fulfilling out-of band requirements and preserving low in-band distortion. Power efficiency of amplification module is improved as well. This solution has been tested by simulation and measurement on a 10-W class AB LDMOS power amplifier.

In this article, the authors study the convergence of an iterative algorithm for the joint estimation of the signal‐to‐noise ratio (SNR) and the transmission channel in orthogonal frequency division multiplexing context. At each step of the algorithm, the authors use the minimum‐mean‐square error (MMSE)‐based SNR estimation, which feeds the linear MMSE channel estimation. Reciprocally, this efficient channel estimation is used to perform the SNR estimation. The authors provide a proof of convergence of the algorithm to a single value. Furthermore, we derive an accurate approximation of the bias of the estimation. Simulations show that the algorithm converges quickly and verifies the theoretical results. They also show the efficiency of both SNR and channel estimation. By comparing with the existing methods, the authors show that the tradeoff between the number of required pilots in the preamble and the performance of the SNR estimation were improved. Furthermore, for a fixed bit error rate, the SNR gap between the proposed channel estimation and the perfect one is <0.5 dB.

The paper tackles the problem of efficient reduction of the out-of-band (OOB) radiation in multi-carrier systems when considering the presence of a nonlinear power amplification. It is important to provide “green” transmitters producing less electromagnetic “pollution” out of its nominal frequency band and obtaining at the same time high energy efficiency of the used power amplifier. One of the known methods assumes appropriate modulation of dedicated subcarriers by specially calculated symbols reducing OOB radiation. The solution proposed in this paper combines two approaches, among which the first, called cancellation carriers, is used traditionally for subcarrier sidelobes minimization, and the second, called tone reservation, for peak to average power ratio reduction. The novelty of this work is in joint minimization of both aforementioned metrics in the near optimal way while keeping low computational complexity. The result is seen as a decreased power of the OOB radiation observed after signal passing through the power amplifier. The obtained results confirm that the proposed algorithm outperforms the approaches in which those metrics are minimized separately. Additionally, a number of simulations has been carried out to investigate the influence of the proposed algorithm parameters on the resultant out-of-band radiation performance.

In this study, the authors look into digital predistortion and its combination with the peak‐to‐average power ratio (PAPR) reduction technique in the case of orthogonal frequency division multiplexing (OFDM)‐based systems. First of all, the authors propose a new predistortion methodology which uses the addition of signals. Two different algorithms are investigated for the predistortion signals generation. The first one is based on the traditional predistortion method, where an estimation of the power amplifiers (PAs) characteristics is needed in the first place. The second algorithm to generate the predistortion signal does not need a priori PA estimation. It is based on an iterative compensation of the error between the amplified signal and the OFDM signal. Then, the authors combine this latter algorithm with the tone reservation PAPR reduction method in order to have a global adding signal expression. Two combination scenarios of PAPR reduction and predistortion obtained by means of adding a signal are proposed. The first one combines both of them in series while the second one is parallel. Performances of the proposed predistortion algorithms and the combination scenarios are compared thanks to simulations based on IEEE802.il a/g standards for a memoryless solid state PA.

Some recent communication systems like DVB-T2 standard set up a PAPR reduction technique followed by a linearization's one. So in such a scenario, the performance of the linearization is influenced undoubtedly by the PAPR reduction method. In this paper, we revisit the EVM metric and evaluate a closed form regarding the performance of both the PAPR reduction technique and the linearization's one. We choose the predistortion as a linearization technique and define a predistortion error. Assuming that the baseband OFDM signal is characterized as a complex Gaussian process, we consider the three top categories of PAPR reduction methods presented in [2] and we first study the distribution of the resulted signal. Then, we derive some theoretical expressions of the first and second order moments of the predistortion error and show that the error depends mainly on the PAPR of the signal after PAPR reduction method and on the predistortion quality. Some simulations compared to our proposed model confirm our results.

Transmitter non-linear components cause distortions when a signal with high Peak to Average Power Ratio (PAPR) is transmitted. High PAPR is a parameter commonly associated to the multi-carrier signals like Orthogonal Frequency Division Multiplexing (OFDM) and Software Radio (SWR). Since SWR is an enabling technology for Cognitive Radio (CR), the signals demonstrate high PAPR in CR context as well. Upon opportunistic spectrum access in CR, PAPR further increases as more carriers (secondary carriers) are added in an already large numbered multi-carrier signal (primary signal). This paper explores the PAPR variations on spectrum access in CR context. Also, the reduction of PAPR in SWR and CR is performed using Tone Reservation (TR). In TR, certain carriers of the data signal are reserved to create a peak reducing signal which on addition to the data signal reduces its peak power. These carriers are called peak reducing carriers (PRC). At first, PAPR is reduced for different SWR signal scenarios. Then the influence of bandwidth, position and power of PRC on he PAPR reduction performance is discussed. Finally, CR PAPR is reduced by presenting a joint pectrum access scheme which implies a part of secondary data carriers as PRC to reduce CR PAPR.

Today's telecommunication systems require more and more flexibility, and reconfiguration mechanisms are becoming major topics especially when it comes to multi-standard designs. This paper capitalizes on the Common Operator technique to present a new common operator for the FFT and Viterbi algorithms. In the present work, the FFT/Viterbi common butterfly is investigated where reuse and power consumption is traded against throughput. Performance comparisons with similar works are discussed in this paper.

High Peak to Average Power Ratio (PAPR) is a critical issue in multi-standard and multi-carrier communication systems. This problem can result in large performance degradation due to the non-linearity of the High Power Amplifier (HPA) or in low power efficiency. The Cognitive Radio (CR) is an efficient technology to meet the Green communications concept. In this paper, we study the PAPR reduction in the context of amplifying signals of several standards. Also, we propose a scenario allowing an opportunistic spectrum access in the context of Cognitive Radio without degrading the system performance keeping the same Input Back-Off (IBO) and thus the same efficiency of the power amplifier. This scenario uses particular Cognitive Radio (CR) sensors, a Hole Detector sensor and a PAPR sensor. The principle of the proposed method will be described. Also, simulation results based on two Tone Reservation (TR) based PAPR reduction techniques will be given in order to validate the proposed concept.

Orthogonal frequency division multiplexing (OFDM), has recently attracted considerable attention because of its features to combat delay spread or frequency selective fading of wireless or wireline channels. One of the major drawbacks of OFDM is the peak-to-average power ratio (PAPR) which leads to an inefficient use of high power amplifiers (HPA) in communications systems. The authors first briefly review the principle of geometric method (GM) that they previously proposed. This method has a couple of well identified drawbacks as the necessity of adding a radio frequency (RF) filter, the increasing of power amplifier band and the bit error rate degradation if PAPR is largely mitigated. Consequently we propose in this paper a new method to improve GM performance. This method mixes tone reservation (TR) technique and GM called ‘TR-GM’ in order to efficiency reduce the high PAPR of OFDM signals. In addition, the proposed TR-GM technique is compared with TR based on second order cone programming (‘TR-SOCP’) and TR based on the gradient-project (‘TR-GP’) techniques in terms of PAPR reduction, average power variation and complexity. The comparative study has shown that, the proposed TR technique seems to be a good compromise between PAPR reduction, complexity, and average power variation.

High peak-to-average power ratio (PAPR) is a critical issue in any multicarrier systems using orthogonal frequency division multiplexing, as terrestrial digital video broadcasting (DVB). It can result in low power efficiency and large performance degradation of systems, due to the nonlinearity of high-power amplifier (HPA). A PAPR reduction method based on tone reservation technique with second-order cone programming (SOCP) approach in terrestrial DVB systems is proposed. The authors first demonstrate the superiority of the SOCP optimisation algorithm compared with an iterative gradient-based algorithm, using the current DVB-T parameters: significant PAPR reduction gains can be achieved with only a very small set of subcarriers in the useful bandwidth, making the proposed method more promising in terms of spectral efficiency. Moreover, the proposed solution presents a very good trade-off between PAPR reduction gain and mean transmitted power increase. An overall study, taking into account the limitation of the power level of the dedicated subcarriers and the evaluation of the performances in presence of a nonlinear HPA, is presented. These performances are given in terms of adjacent channel power ratio and bit error rate. The resulting PAPR reduction gain demonstrates that the relevance of the proposed method for the future DVB-T standard is straightforward.

Peak-to-mean envelop power ratio (PMEPR) statistical analysis in continuous OFDM context is addressed. After having precisely defined this term which characterizes OFDM signal fluctuations, first statistical order derivation of PMEPR from two already developed distribution functions for continuous base-band OFDM signals is proposed. In literature, one of these two functions is simulation based and lacks any theoretical justifications. It is demonstrated that first statistical order of these two distributions is almost same which provides the analytical justification of the correctness of the simulation based distribution function. Moreover, it has been revealed that the second statistical order of the PMEPR valid for an oversampling factor of one (discrete signal), could also be adopted for continuous signals. PMEPR distribution function associated with continuous OFDM signal is proposed.

SoftWare radio (SWR) is an enabling technology for cognitive radio (CR) systems which promises to (de) modulate any signal, at any frequency. SWR signal therefore is composed of different standard's signals, and each standard's signal is either multicarrier or multiplex of single carriers. This combination leads to high temporal fluctuations and thus SWR signal inherits high peak to average power ratio (PAPR) or simply high power ratio (PR). Nonlinear analogue components (amplifiers, converters etc.) cause distortions (in and out of band distortion) for high PR signals which result in system performance degradation. Usually PR problem is addressed in time domain, and here frequency domain interpretation of PR which is more appropriate in SWR context is presented. Gaussian equivalence between SWR signal and orthogonal frequency division multiplexing (OFDM) signal is proved first to accentuate high PR issue in SWR as OFDM suffers the same problem. Then frequency domain interpretation of PR metric is discussed which results in a PR upper bound. This PR upper bound depends only upon spectral values of the signal thus associates spectrum with PR. As a result this bound assists in spectrum access for CR systems by providing PR metric information related to any available bandwidth. Thus bandwidth allocation in a spectrum access scenario under PR constraint is simplified.

In this paper, we investigate the complexity of a common FFT-like butterfly capable of carrying out both modular and complex arithmetic operations. This idea of resource sharing stands for software radio systems where re-configurability is of major importance for an optimal multi-standards terminal design. By taking into account, in the implementation on STRATIX II devices, the required number of logic blocks and the total execution time, this re-configurable butterfly can achieve a performance-to-cost ratio gain around 20% over the basic duplicated solution where no re-configuration is considered.

The "software radio (SWR)" concept has become a topic of widespread interest for reconfigurable mobile architecture design. It is seen as the next evolutionary step in the mobile communications. In this context of SWR, a way to decrease the runtime of the software reconfiguration and to optimize the sharing between the software and the hardware of the execution platform called "parametrization" was introduced. This technique is based on two approaches, the first one is called the common function approach, the second one is called the common operator approach. Being interested on the second parametrization technique, we propose in this paper a reconfigurable FFT (fast Fourier transform) operator. This operator can be reconfigured to switch from an operator dedicated to compute the FFT in the complex field (i.e for OFDM modulation or frequential equalization) to an operator which computes the FFT in the Galois field in order to perform Reed-Solomon (RS) encoding and two steps of the decoding process

Indoor wireless local networks (WLAN) development in the millimetre band gives new perspectives, which are very promising in terms of announced data rate and offered services. Nevertheless strong free space attenuation as well as pieces of furniture and wall attenuations result in difficult propagation conditions. A French research project (RNRT COMMINDOR) has been set up to study and design new high data rate (155 Mbit/s) radiocommunication systems at 60 GHz in an indoor environment. SIRADEL takes part in this project by modelling the propagation phenomenon thanks to a ray-tracing tool associated to the Uniform Theory of Diffraction (UTD). Simulations are then compared to measurements realised within the framework of this project by the LCST Laboratory of INSA Rennes. The good behaviour of the propagation model is analysed for LOS and NLOS situations.