Bruno Paille

Analysis of Binary CPFSK With Non-Uniform Sampled Reception

In this paper, the impact on the bit error rate (BER) of the periodic non-uniform sampling implied by a power-gated analog-to-digital converter (ADC) is addressed in the specific case of a binary CPFSK receiver. Analytical and simulated lower bounds of the BER in an additive white Gaussian noise channel for several phase-based estimators are presented and discussed together with their dependency on the sampling synchronization. The main results are summarized in a practical abacus for Minimum Shift-Keying (MSK) modulation. Finally, the proposed techniques are evaluated against the IEEE 802.15.4 specification in MSK mode and lead to an active time ratio of the ADC of only 10% or less. Application of the proposed technique to a more competitive IEEE 802.15.4 compliant architecture available in the literature is also presented.

Distance measurement using narrowband ZigBee devices

Zigbee, also known as IEEE 802.15.4 is a popular wireless communication standard developed for simple low-power and low-cost wireless applications. One of these applications is local positioning, which consists in inferring the position of a device in real time. In this paper, a new method to precisely measure distance using standard ZigBee devices is presented. The measurement uses only a 2 MHz bandwidth channel and compensate the lack of bandwidth by using an original technique for measuring Time Of Arrival. Simulations show that our method achieves a standard deviation of 33 cm, which is better than other approaches in the same testing conditions. The technique is tested under a real indoor environment, and the results are finally compared with the simulations.

RF Power Gating: A Low-Power Technique for Adaptive Radios

In this paper, we propose a low-power technique, called RF power gating, which consists in varying the active time ratio (ATR) of the RF front end at a symbol time scale. This technique is especially well suited to adapt the power consumption of the receiver to the performance needs without changing its architecture. The effect of this technique on the bit error rate (BER) performances is studied for a basic estimator in the specific case of minimum-shift keying signaling. A system-level energy model is also derived and discussed to estimate precisely the power reduction based on the characteristics and the power consumption of each block. This model allows highlighting the different contributors of the power reduction. The BER results and the energy model are finally merged to determine the best ATR meeting the design constraints. Applying this technique to the IEEE 802.15.4 standard, this paper shows that an ATR of 20% is a good tradeoff to meet the packet error rate constraint while maximizing the energy reduction ratio. Using typical block power consumptions, an energy reduction ratio around 20% can be reached. Even better energy reduction ratios (~60%) are also achievable when most of the blocks are power-gated.

Digital cubic interpolation and synchronization for RF receiver using power-gated ADC

In this paper, an implementation of both interpolation and synchronization modules designed for RF receiver using power-gated ADC (PG-ADC) is presented. These modules allow lower bit error rates when demodulating non-uniformly sampled minimum-shift keying (MSK) signal. The proposed architectures are synthesized using CMOS 90 nm technology and are shown to have small occupied area (≈0.05 mm2) and low power consumption (tens to hundreds of μW). The results are detailed for several input data rates and interpolation factors.

New technique to resolve carrier-phase cycle ambiguity for narrowband low-power systems

This paper presents a new approach to resolve an ambiguity zone of carrier phase measurements of low power devices. It is based on a Time Difference Of Arrival method. It reliably resolves the ambiguities between two reference points and a transceiver. Simulation are based on a low-power state-of-the-art ZigBee radio architecture. The results show that with a ZigBee channel and 12 MHz sampling frequency it is possible to reliably measure distances from 25cm to 25m without phase ambiguities and with a standard deviation lower than 20cm.