Manel Ben-Romdhane

Non Uniform Sampled signal reconstruction for software defined radio applications

This paper focuses on digital reconstruction methods of uniform signal from its non uniform samples. A specific Non Uniform Sampling (NUS) technique for controlling Analog-to-Digital Conversion (ADC) in a multi-standard radio receiver is presented. Several reconstruction algorithms are summarized and a general mathematical formula is used to describe these algorithms. Different methods are classified into two types: iterative and interpolation methods. For radio communications context, performances in terms of accuracy of reconstruction and computational complexity, are shown and compared for these algorithms.

Non-uniform sampling schemes for IF sampling radio receiver

The IF sampling radio receiver based on the non-uniform sampling (NUS), technique is promising and would be a candidate for the multistandard reception. This technique allows the IF down-conversion and permit to eliminate or alleviate the anti-aliasing filter. For wideband and multistandards design, the choice of sampling rates for bandpass sampling is flexible. This paper introduces the NUS theory, particularly its random processes schemes; the additive random sampling (ARS) and the jittered random sampling (JRS). Then, it proposes the IF NUS receiver architecture. The reconstruction algorithm RA block represents the object of the comparison between the sampling schemes. Finally, validation of the algorithm, its anti-aliasing specificity and some simulation results are presented

Nonuniformly Controlled Analog-to-Digital Converter for SDR Multistandard Radio Receiver

A new multistandard radio receiver architecture is presented to take advantage of nonuniformly controlled analog-to-digital converters (ADCs). By defining the statistical parameter related to the random sampling frequency, a time-quantized random sampling scheme is considered to design a nonuniform sampling-based software defined radio (SDR) multistandard receiver. A relaxed design is proposed for an E-GSM/UMTS/IEEE802.11a multistandard receiver. The designed baseband stage avoids the use of the automatic gain control block, relaxes the nonprogrammable antialiasing filter to the third order, and converts data with a 16-bit ADC at a 124-MHz mean sampling frequency.

Pseudorandom clock signal generation for data conversion in a multistandard receiver

In previous work, a non-uniform sampling (NUS) technique to control analog-to-digital conversion (ADC) in a multistandard radio receiver was proposed. In this context of wide band radio signals, the NUS-based ADC offers the advantages of relaxing antialiasing filter (AAF) constraints, decreasing the sampling frequency average and reducing ADC dynamic power consumption. In this paper, we focus on generating non-uniform clock for the sample and hold block of the ADC. The proposed non-uniform clock is based on quantified clock timing. Non-uniform clock is generated from digital control unit (DCU). The DCU is composed of a Gray counter, a linear feedback shift register (LFSR) and a multiplexer to generate specified signals and to select the required clock phase. Simulation results show that performances are similar for conventional uniform sampling (US), additive random sampling (ARS) and time quantized additive random sampling (TQ-RS) for different quantizing factors.

Flexible baseband analog front-end for NUS based multistandard receiver

Non-uniform sampling (NUS) controlling baseband analog front-end in a Software Defined Radio multistandard receiver was previously proposed in our works. Non-uniform sampling offers the alias-free sampling feature. Non-uniform sampling based multistandard receiver relaxes Anti-Aliasing Filter (AAF), relaxes automatic gain control circuit and reduces power consumption of the analog-to-digital converter. In this paper, for a finite number of samples, we adopt Bilinskiss theoretical results to multistandard radio signals. The obtained NUS attenuations are relevant to design a flexible AAF. Some comparative AAF orders are presented to figure out NUS advantages in spite of finite number of samples.

Data acquisition test platform for non uniformly controlled ADC

Non Uniform Sampling (NUS) was presented as an emerging solution to reduce aliases for ADC (Analog-to-Digital Converter) in Software Defined Radio receiver. In this paper, practical implementations of NUS, called TQ-RS (Time Quantized Random Sampling) are presented. A test setup for non uniformly controlled data acquisition system is detailed. Experimental results are presented and discussed.

Pseudo-random Direct Sampler for frequency down-conversion in a multi-standard receiver

For software defined radio, non uniform sampling (NUS) is a process promising IF down-conversion with alias reduction. Applied to multi-standard receiver, this technique relaxes system design constraints. This paper presents a new design strategy for clock generation in NUS based multi-standard radio receiver supporting GSM, UMTS and Wi-Fi standards. Sampling frequency choice is discussed in order to get only one shared anti-aliasing filter suitable for all considered standards. The proposed non uniform clock generator, the pseudo-random direct sampler (PDS), promises a direct driving of the sampler circuit leading to low-power oriented design regarding classic RF sampling receiver.

Non uniform sampling for power consumption reduction in SDR receiver baseband stage

In this paper, authors point out the effect of non uniform sampling (NUS) on the power consumption in SDR receiver baseband stage. This feature is drawn by theoretical formulas regarding spectrum shape and power estimation of different baseband components. An example is drawn to focus on NUS ability to reduce anti-aliasing filter (AAF) consumption by 25%.

Towards time-quantized random sampling for multistandard receiver baseband stage

In this paper, the ability of time-quantized random sampling (TQ-RS) to reduce aliases is discussed. Authors present simulation results of power spectrum density of a time-quantized random sampled signal. The oversampling ratio impact on alias reduction is outlined. TQ-RS application is proposed for baseband stage design of software defined radio receiver supporting the GSM, the UMTS and the IEEE802.11a standards. Obtained design results are compared to design results considering the uniform sampling. This comparison shows that the anti-aliasing filter order has been reduced from 4 to 3 and the maximal gain of automatic gain control is decreases with at least 12 dB. A test setup for data acquisition system with TQ-RS is detailed. Validation results confirm the targeted performances in terms of signal-to-noise ratio (SNR) of TQ-RS acquisition. The SNR is equal to 53.13 dB in TQ-RS compared to 54 dB in uniform sampling.

Test setup and spurious replicas identification in time-quantized pseudorandom sampling-based ADC in SDR multistandard receiver

Software defined radio (SDR) multistandard receiver is an enabling technology for radio evolution. The time-quantized pseudorandom sampling (TQ-PRS) is an advantageous processing for SDR multistandard receiver design. The TQ-PRS allows aliases attenuation leading to a relaxed receiver baseband stage. In this paper, the authors focus on experimental proof of concept of the TQ-PRS-based analog-to-digital converter (ADC). The spectrum analysis of the test results shows spurious replicas which are not present in simulation results. The presented investigations show that the spurious replicas are coming from a pseudorandom delay with the same periodicity as TQ-PRS clock. A solution based on sharing receiver channel selection filter for spurious attenuation is proposed.