Harri Viittala

Different experimental WBAN channel models and IEEE802.15.6 models: Comparison and effects

In this paper, a summary of the IEEE802.15.6 wireless body area network (WBAN) radio channel models is given and the models are compared to the corresponding results obtained from the measurements carried out at the Oulu University hospital, Oulu, Finland. CWC has done a set of experimental UWB on-body channel modeling independently of the measurements that are behind the IEEE model. Being statistically more reliable, CWCs results correspond with the models presented by the IEEE806.15.6 task group. Different scenarios for the WBAN link setups have been considered in both campaigns.

Measurement and modelling of an UWB channel at hospital

This paper describes the results of an ultra wideband (UWB) channel measurements and modelling from 3.1 to 6.0 GHz carried out at the Oulu University Hospital. Mainly line-of-sight (LOS) channels were measured having transmitter-receiver separation from 3 to 6 m. The modelling is done in time domain and in frequency domain, and the results are compared with. Channel parameters that are corresponding to the modified Saleh-Valenzuela (SV) model in time domain and autoregressive (AR) model in frequency domain are extracted from the measurement data. Also, delay spreads and path losses are examined. In the study, the effect of the huge frequency diversity over the UWB band on the path loss is pointed out.

Impact of difference in WBAN channel models on UWB system performance

In this paper, the performances of two singleband ultra wideband (UWB) systems, i.e., direct sequence UWB (DS-UWB) and UWB frequency modulation (UWB-FM) are studied in two different channel models to reveal an impact of a channel model on the systems performance. The applied channel models are the experimental wireless body area network (WBAN) channel model developed at the Centre for Wireless Communications (CWC), Finland, and the IEEE 802.15.6 channel model. The simulation results indicate that the choice of the WBAN channel model applied in the simulations has a major impact on the performance of UWB-FM, whereas it is not such a crucial in the case of DS-UWB.

An Experimental Evaluation of WiFi-Based Vehicle-to-Vehicle (V2V) Communication in a Tunnel

New automated solutions are needed, e.g., in mining industry to improve efficiency and productivity of every process. In addition, costs have to be reduced, and health and safety of employees need to be enhanced. This paper studies vehicle-to-vehicle (V2V) communication to be utilized in, e.g., mining vehicles in a tunnel to increase safety and productivity of a transportation of mining goods. The objective of the paper is to experimentally evaluate maximum achievable range of WiFi radio in a real tunnel environment including line-of-sight (LOS) and non-LOS (NLOS) links. The measurement campaign was carried out in an artificial tunnel using commercial off-the-shelf WiFi radios and antennas. The experimental system was able to reach 150 m range when applying a single data stream, and 100 m for two simultaneous data streams without loss in throughput.

Medical applications adapting ultra wideband: a system study

In order to find the best solution of physical layer for medical wireless body area network (WBAN), two single-band ultra wideband (UWB) systems are studied, i.e., direct sequence ultra wideband (DS-UWB) and ultra wideband frequency modulation (UWB-FM). UWB is considered to be one of the most feasible techniques among those that can be applied to medical WBAN since it provides low power consumption, simple transceiver structure and good coexistence characteristics due to a low power spectral density. The simulation results indicate that UWB-FM has better performance than non-coherent DS-UWB in overall. It was expected that coherent DS-UWB with multiple rake fingers gives the best results, and this was justified by the simulation results.

Emulation of secure Wi-Fi communication: A performance gap analysis against a virtual test-bed

Wireless local area networks (WLANs) gained evergrowing importance in public transportation systems where they are selected to reduce installation costs and introduce new services. However, the introduction of a wireless interface in safety critical applications implies different communication protocol analysis and the introduction of a security layer is indispensable to implement defenses from malicious attacks. Host Identity Protocol (HIP) based network with IPSec is the network architecture proposed to secure wireless communications in large public transportation system. This paper analyses a comparison between the proposed architecture tested in a real environment and in an emulated scenario. The measurement campaign was carried out in outdoor using commercial on the shelf (COTS) Wi-Fi devices. The Common Open Research Emulator (CORE) with the Extendable Mobile Ad-hoc Network Emulator (EMANE) framework were used to evaluate the same scenario in a virtual test-bed. Results indicate how the end-to-end secure wireless communication built in the emulator works similarly to an intra-vehicular on-board network.

ETSI SmartBAN System Performance and Coexistence Verification for Healthcare

European Telecommunications Standard Institute (ETSI) Technical Committee (TC) Smart Body Area Network (SmartBAN) defines and specifies low-power physical and medium access control layers for SmartBANs. Several use cases have been defined for SmartBAN, such as sleep monitoring, fall monitoring, and apnea monitoring. The specialist task force 511, working under ETSI TC SmartBAN, studied the performance of the system and evaluated coexistence with other wireless systems. In this paper, the simulator model based on the SmartBAN specification is introduced. Based on the simulation results, the receiver sensitivity for the SmartBAN system is defined. In addition, the interference model extracted from the measurements in the Oulu university hospital is discussed. This paper presents the summary of the simulation results based on the above-mentioned interference models. The simulation results showed that when there is a high interference in a communication channel, the SmartBAN system cannot gain an acceptable frame error level without a physical layer protocol data unit repetition technique and a high signal-to-interference power ratio level (SIR). In a low interference scenario, repetition is also needed when SIR is less than 9 dB.

Zone-based fuzzy routing for WBANs

Heterogeneous nature of Wireless Body Area Networks (WBANs) including different types of nodes, applications and environments sets great challenges for a routing protocol. We will present routing challenges set by WBAN and its applications, go through existing protocols and their flaws. In the end, we will give a novel routing protocol using different zones and fuzzy logic.

Security of Wi-Fi on-board intra-vehicular communication: Field trials of tunnel scenario

Wireless communications are increasingly-often selected as a cable replacement for on-board vehicular networks. When a wireless technology implements safety critical application, cryptographic countermeasures are required. This paper describes the impact of security on intra-vehicular communication in a real tunnel scenario, e.g. for urban transit or mining vehicles where the usage of security is mandatory in order to maintain the system safety. The measurement campaign was carried out in a sport ski-tunnel using commercial off-the-shelf (COTS) Wi-Fi modules. The objective was to understand the impact of overhead on security in a tunnel considering line-of-sight (LOS) and non-LOS (NLOS) scenarios. In addition, the study compared different solutions for security to evaluating lesser known protocols. These field trials showed that wireless security is feasible up to 300 m in NLOS without repeaters. Finally, the experiment presented confirms the effectiveness of the Host Identity Protocol when used as standalone or in combination with other security solution.

Performance of the ETSI SmartBAN system in the interfered IEEE 802.15.6 channel

The ETSI TC SmartBAN defined system is designed for body area networks supporting both on-body links and links to implanted devices. The system operates at the 2.4 GHz ISM band, where there are also other wireless radio systems, such as Bluetooth and WiFi. The SmartBAN system simulation model has been created to Matlab and the system performance was studied in the IEEE 802.15.6 channel model 3 with a measurement based interference model. The interference model is based on the measurement campaigns carried out in the Oulu university hospital. By using these simulation models, comparative analysis between BCH encoding schemes (127,113) and (36,22) on the system performance was carried out. It is shown that a higher coding rate has better performance in the presence of interference but it needs a repetition method to gain an acceptable frame error rate.