Christian Roland

A new concept for wireless reconfigurable receivers

In this article we present the Self-Adaptive Universal Receiver (SAUR), a novel wireless reconfigurable receiver architecture. This scheme is based on blind recognition of the system in use, operating on a new radio interface comprising two functional phases. The first phase performs a wideband analysis (WBA) on the received signal to determine its standard. The second phase corresponds to demodulation. Here we only focus on the WBA phase, which consists of an iterative process to find the bandwidth compatible with the associated signal processing techniques. The blind standard recognition performed in the last iteration step of this process uses radial basis function neural networks. This allows a strong analogy between our approach and conventional pattern recognition problems. The efficiency of this type of blind recognition is illustrated with the results of extensive simulations performed in our laboratory using true data of received signals.

Promising Technique of Parameterization For Reconfigurable Radio, the Common Operators Technique: Fundamentals and Examples

In the field of Software Radio (SWR), parameterization studies have become a very important topic. This is mainly because parameterization will probably decrease the size of the software to be downloaded, and also because it will limit the reconfiguration time. In this paper, parameterization is considered as a digital radio design methodology. Two different techniques, namely common functions and common operators are considered. In this paper, the second view is developed and illustrated by two examples: the well known Fast Fourier Transform (FFT) and the proposed Reconfigurable Linear Feedback Shift Register (R-LFSR), derived from the classical Linear Feedback Shift Register (LFSR) structure.

A near-optimal multiuser detector for MC-CDMA systems using geometrical approach

An efficient sub-optimal algorithm, called HIS (hyperplane intersection and selection) detection algorithm, is proposed to solve the problem of joint detection of K users in an MC-CDMA system. Compared to existing solutions, the proposed algorithm has three characteristics very attractive for practical. systems. Firstly, it has nearly optimal performance. Secondly, it has a low computational complexity - O(K/sup 2/) multiplications and O(K/sup 3/) additions. Third, the algorithm has an inherent parallelism. To our knowledge, the HIS algorithm is not just an add-on to an existing algorithm, but rather a new decoding technique based on a singular value decomposition of the channel matrix, H. After giving the equation of the MC-CDMA multi-user detection problem, the HIS algorithm is described. Its performance is compared to known existing algorithms (ZF, MMSE, PIC and sphere decoding). For a BER as low as 10/sup -4/, the HIS algorithm introduces only 0.2 dB degradation compared to the optimal sphere decoding algorithm for K=16 users against 3.8 dB for the PIC algorithm with two MMSE stages.

Efficient multiplierless architecture for frame synchronization in DVB-S2 standard

The first challenging step of the demodulation of the DVB-S2 signal with function of VCM (Variable Coding and Modulation)/ACM (Adaptive Coding and Modulation) is the detection of the Physical Layer (PL) header. PL header is transmitted using π/2-BPSK modulation and is composed of a fixed part (26 bits of Start Of Frame (SOF)) and a variable part (64 bits codeword of PL Signaling (PLS) code that defines the structure of the PL frame). Since the 90 bits corresponding to the PL header are affected by noise, the carrier frequency offset and the phase noise, the synchronization task in a DVB-S2 receiver is thus a critical task. In this paper, we present a properties of the Hadamard code used to encode the information of the PLS code to reinforce frame detection before knowing the actual value of the PL code. Moreover, we propose to perform the computation in the polar domain in order to avoid the need of multiplier and thus, to obtain a very low cost implementation. The associated decoder architecture is presented together with the measured performance at several SNRs.

Quasi-maximum-likelihood detector based on geometrical diversification greedy intensification

This letter proposes a quasi optimum maximum likelihood detection technique based on Geometrical Diversification and Greedy Intensification (GDGI). The presented detector scheme is shown to achieve almost optimal performance for all signal-to-noise ratio (SNR) values and a cubic computation complexity in the problem dimension. It possesses a regular structure well suited for hardware implementation. Simulation results show that for a system with a high dimension of n = 60, the loss is approximately 0.35 dB at BER=10-5 compared to an optimal decoding.

Low-complexity energy proportional posture/gesture recognition based on WBSN

This paper addresses the issue of low-power posture and gesture recognition in indoor or outdoor environments without any additional equipment. For applications based on predefined postures such as environment control and physical rehabilitation, we show that low cost and fully distributed solutions, that minimize radio communications, can be efficiently implemented. Considering that radio links provide distance information, we also demonstrate that the matrix of estimated inter-node distances offers complementary information that allows for the reduction of communication load. Our results are based on a simulator that can handle various measured input data, different algorithms and various noise models. Simulation results are useful and used for the development of real-life prototype.

Probability-Driven Simulated Annealing for Optimizing Digital FIR Filters

In this paper, we propose to mimic some well-known methods of control theory to automatically fix the parameters of a multi-objective Simulated Annealing (SA) method. Our objective is to allow a decision maker to efficiently use advanced operation research techniques without a deep knowledge of this domain. Classical SA controls the probability of acceptance using an a priori temperature scheduling (Temperature Driven SA, or TD-SA). In this paper, we simply propose to control the temperature using an a priori probability of acceptance scheduling (Probability Driven SA, or PD-SA). As an example, we present an application of signal processing and particularly the design of digital Finite Impulse Response (FIR) filters for very high speed applications. The optimization process of a FIR filter generally trades-off two metrics. The first metric is the quality of its spectral response (measured as a distance between the ideal filter and the real one). The second metric is the hardware cost of the filter. Thus, a Pareto-based approach obtained by a multi-objective simulated annealing is well suited for the decision maker. In this context, TD-SA and PD-SA method are compared. They show no significant differences in terms of performance. But, while TD-SA requires numerous attempts to set an efficient temperature scheduling, PD-SA leads directly to a good solution.

Improved Multiplierless Architecture for Header Detection in DVB-S2 Standard

One of the first processing steps in a DVB-S2 signal receiver is the detection of frames header. Recently, an architecture using only the phase information of the received samples was proposed. In this paper several optimization in algorithm/architecture are proposed, leading to better performance and reduced hardware complexity. For an SNR of -3 dB, the probability of miss detection of the header detector is reduced from 0.7 down to 0.52 for a constant false alarm probability of 10-6.

Radio signature based posture recognition using WBSN

A body network of Inertial Measurement Units (IMUs) is a well known solution for posture recognition based on accelerometer and magnetometer data fusion. However sensors and especially the magnetometer can be disturbed by the environment. Considering a Wireless Body Sensor Network (WBSN), we propose to use available radio received power measurements as an alternative to the magnetometer. We show with simulation and real data, that the radio signal used for WBSN communications can also provide useful location information despite highly noisy Received Signal Strength Indications (RSSI). We propose a solution for the static case that leads to a very simple yet Efficient algorithm.