A Receiver Architecture for Devices in Wireless Body Area Networks

Abstract

A receiver architecture suitable for devices in wireless body area networks is presented. Such devices require minimum physical size and power consumption. To achieve this the receiver should therefore be fully integrated in state-of-the-art CMOS technology, and size and power consumption must be carefully considered at all levels of design. The chosen modulation is frequency shift keying, for which transmitters can be realized with high efficiency and low spurious emissions. A directconversion receiver architecture is used to achieve minimum power consumption and a modulation index equal to two is chosen, creating a mid-channel notch in the modulated signal. A tailored demodulation structure has been designed to make the digital baseband compact and low power. To increase sensitivity it has been designed to interface with an analog decoder. Implementation in the analog domain minimizes the decoder power consumption. Antenna design and wave propagation are taken into account via simulations with phantoms. The 2.45 GHz ISM band was chosen as a good compromise between antenna size and link loss. An ultra-low power medium access scheme has been designed, which is used both for system evaluation and for assisting system design choices. Receiver blocks have been fabricated in 65-nm CMOS, and an RF front-end and an analogto-digital converter have been measured. Simulations of the complete baseband have been performed, investigating impairments due to 1/f noise, frequency and time offsets. Index Terms-Body sensor networks, CMOS integrated circuits, Low power electronics, Receivers, System-on-a-chip I. INTRODUCTION HERE are numerous applications for ultra-low power wireless communication. For instance, it can benefit such different areas as health care [1] and smart buildings [2], [3]. To achieve ultra-low power consumption it is important to combine low-power transceiver circuits with optimized communication protocols. In medical implants this is critical Manuscript received October 6, 2011.

A Novel Intrabody Communication Transceiver for Biomedical Applications

“…We suggest a carrier-free scheme based on IR for the IBC hardware design. We argue that an optimal modulation scheme for IR-IBC would fulfill the requirements to design a more efficient IBC hardware [100].…”

“…In terms of the complexity of different modulation schemes, both schemes are the potential candidates that allow the implementation of simple transmission circuit. The channel noise detection is simple in PPM compared to OOK, due to the constant envelope of PPM [100]. Unlike OOK, a threshold to distinguish signals and noise is not required in PPM [101].…”

Antennas and Propagation for In-Mouth Tongue-Controlled Devices in Wireless Body Area Networks

“…For the link budget, the receiver architecture for WBANs discussed in [12] is considered where at the bit-error-rate (BER) of 0.001, the required Signal-to-Noise (SNR) per bit (E b /N 0 ) for the demodulation in the coded case was found to be 10 dB. As the application here is a low data rate application, considering a maximum data rate of 125 kbps will give the receiver sensitivity (S RX ) of −97 dBm as calculated in [12].…”

SmartGate – connecting wireless sensor nodes to the Internet

“…Applications of the IoT in logistics and environment can be found in Atzori et al (2010). Examples of wireless sensor networks in health care can be found in De Boeck (2011) and Sjoland et al (2012). For an increasing amount of applications, the connection of the WSN (wireless sensor network) to the Internet is an attractive feature.…”