Channel Characterization and Robust Tracking for Diversity Reception over Time-Variant Off-Body Wireless Communication Channels

Vanveerdeghem

2013 IEEE 20th Symposium on Communications and Vehicular Technology in the Benelux (SCVT)

et al. 2013

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Abstract-Off-body wireless communication applications range from fall-detection systems for the elderly to monitoring networks for rescue workers. Further development of practical body-worn systems requires compact, low-cost and low-power battery-powered equipment. A versatile wearable network node offering all these features, including a powerful microcontroller for data processing and additional memory for local data logging was designed and implemented. The node allows receive diversity, mitigating the negative impact of fading, which is typically present in indoor propagation environments. Channel measurements are performed for an indoor Non Line-of-Sight communication between two nodes. Mobile-to-base-station as well as mobile-to-mobile links are considered. A statistical analysis of the performance determines outage probability with and without receiver diversity for both link types, showing a significant diversity gain in all cases. Correlation properties, level crossing rate and average fade duration are also determined.

Section: A Measurement Setupmentioning

confidence: 99%

Energy-efficient off-body communication nodes with receive diversity

Vanveerdeghem

2013 IEEE 20th Symposium on Communications and Vehicular Technology in the Benelux (SCVT)

et al. 2013

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“…One approach consists of reducing the overhead in terms of pilot symbols that are needed to make accurate channel estimates at the receiver. This is done by implementing data driven channel tracking [9], where we use the detected data symbols as substitutes for the pilot symbols to keep track in time of the correct channel state. Fig.…”

Section: Energy-efficient Multi-antenna Processing Techniquesmentioning

confidence: 99%

Active Textile Antennas as a Platform for More Energy-Efficient and Reliable Wireless Links in Healthcare

Declercq

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering

et al. 2013

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Abstract. New wireless wearable monitoring systems worn by patients and caregivers require a high degree of reliability and autonomy. We show that active textile antenna systems may serve as robust platforms to deploy such wireless links, in the meanwhile being comfortable and invisible to the wearer, thanks to recent developments in the design process combined with dedicated signal processing techniques. The key idea is to exploit the large amount of real estate available in patients' and caregivers' garments to deploy multiple textile antennas each with a size large enough to make them efficient radiators when deployed on the body. The antenna area is then reused by positioning active electronics directly underneath and energy harvesters directly on top of the antenna patch, ensuring the autonomy of the module. Combining different antenna signals by means of low-power multi-antenna processing techniques then ensures good signal quality at low transmit power in all situations.

“…We will present results with and without these extra pilot symbols. The timevarying channel can be tracked without significant processing overhead at the receiver, as illustrated in [4], if a small residual channel estimation error can be tolerated. Channel tracking schemes, as documented in [5]- [10] can track the channel more accurately at the price of a higher computational complexity.…”

Section: ) Evolution Of the Complex Channel Estimatesmentioning

confidence: 99%

Energy-efficient off-body data transmission by means of antenna diversity and tracking of the time-variant wireless channel state

Vallozzi

2012 6th European Conference on Antennas and Propagation (EUCAP)

et al. 2012

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Abstract-Textile antennas integrated into the garment of rescue workers offer a convenient way for implementing an offbody communication system. When operating indoors, the link reliability is compromised by fading and shadowing. For a SISO system, the transmitted power needs to be very large to allow an acceptable bit error rate at the receiver. Employing front and back dual-polarized textile antennas creates fourth order diversity at the body. Equipping also the base-station with such a pair of antennas results in diversity at both sides, in this case realizing a 4 × 4 MIMO system. The MIMO techniques counter the effects of fading and shadowing and allow the system to achieve low bit error rates at the receiver with a minimum of transmitted power. Long data frames are used with a minimum pilot symbol overhead, also reducing the transmitted power per data bit. Although the propagation channel is time-varying during the transmitted frame, the channel variation is tracked at the receiver with a minimal processing power.