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ETSI TC SmartBANOverview of the Wireless Body Area Network Standard

Matti Hämäläinen1

, Tuomas Paso1

, Lorenzo Mucchi2

, Marc Girod-Genet3

,John Farserotu

4, Hirokazu Tanaka

5, Woon Hau Chin

5, Lina Nachabe Ismail

3

1University of Oulu, PO Box 4500, FI-90014 University of Oulu, Finland, {matti.hamalainen, tuomas.paso}@ee.oulu.fi2University of Firenze, via di S. Marta, n.3, I-50139 Firenze, Italy, [email protected]

3Telecom SudParis, 9 rue Charles Fourier, 91011 Evry Cedex, France, {marc.girod_genet, lina.nachabe-ismail}@telecom-

sudparis.eu4CSEM SA, Rue Jaquet-Droz 1, CH-2002 Neuchâtel, [email protected]

5Toshiba Research Europe Ltd., 208 Cambridge Science Park, Milton Rd, Cambridge CB4 0GZ, UK, {Hirokazu.Tanaka,woonhau.chin}@toshiba-trel.com

Abstract—This paper gives an overview of the European level

standard proposal for smart wireless body area networks

(WBAN). Under the mandate of European TelecommunicationStandards Institute ETSI, a technical committee TC SmartBAN

was formed in 2013. The goal of the TC SmartBAN is to define a

standard for low power devices and networks to be used in short

range links supporting, e.g., healthcare, wellness and sport

relating applications operating around a human body. The main

focus areas were in physical and medium access control layers’

specifications as well as efficient data presentation format for

information delivery. Moreover, experimental measurement

campaigns to characterize radio channel occupancy in the

specified SmartBAN frequency range have been carried out. The

actual work is divided into several, parallel Work Items (WI).

Within this paper, a short overview of the ETSI TC SmartBAN

work is given. The components of the SmartBAN standard are

described in their own dedicated papers.

Keywords—healthcare, wellfare, leisure, short range,

communication, low power, energy efficiency, coexistence.

I.

INTRODUCTION

The aging population in the developed world, coupled withincreasing health awareness and individualized services, havetriggered considerable attention and demand for developingwearable healthcare devices for monitoring vital signs anddetecting serious health conditions. In addition, ageing peopleare preferable staying at home instead of being hospitalized.This is a global trend, not only European. Novel, easy to usedevices can encourage the growth of tele-health and also helpto mitigate the burgeoning healthcare costs that many countriesare now facing with. Modern healthcare services are nowadaysalso changing their paradigm to focus more on individualizedand proactive healthcare rather than only contributing whenpeople are already sick. This means that people will take moreresponsibility on their own health. Additionally, wearablemonitoring devices and techniques can be used in sports,fitness, etc. and also to increase diagnostic rates relating tovarious diseases and health conditions.

Wearable healthcare devices can monitor a variety ofpsycho-physiological signals, including audio, visual, and

environmental data in addition to human vital signs. As aresult, any wireless links connecting these devices have to

adapt to various requirements given to, e.g., data rate andquality of service (QoS). Additionally, due to the small size ofthe wearable devices, they will have limited energy storagecapability. As a result, any communication protocols in placemust be simple, robust and power efficient, and they shouldalso be easy to use in self-monitoring purposes.

Under the mandate of European TelecommunicationStandards Institute (ETSI), a Technical Committee (TC)SmartBAN was established in 2013 to develop and maintain anETSI Standard and Specification, reports, guides, etc. relatingto smart wireless body area networks. Within ETSI TCSmartBAN work, specifications for low power physical layer(PHY), medium access control layer (MAC) and suitable light

data presentation formats are defined. At the beginning of theprocess, the application fields were limited to healthcare,welfare, sports and leisure, but the standard could also beapplied to other application fields.

In addition to communication protocols for PHY and MAClayers, the work is focusing on features on security andcoexistence highlighted for different applications and services.Essential technical features of Smart BANs are ultra-low powercommunication, support for required varying data rates andQoS, and a robust coexistence strategy.

The corresponding work has already been done by theInstitute of Electrical and Electronics Engineers (IEEE), whoreleased the IEEE802.15.6-2012 standard for wireless bodyarea networks in February 2012 [1]. This standard utilizedthree different PHYs which are merged by a common MAC.The standard [1] itself is not light and that is a reason whyETSI would like to develop its own standard for WBAN. Theadvantages SmartBAN will provide compared to [1] aredescribed later in this paper.

This paper is organized as follows. Chapter II describes thesystem requirements given to TC SmartBAN. Chapter IIIintroduces the SmartBAN data representation format. Chapter

2015 9th International Symposium on Medical Information and Communication Technology (ISMICT)

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IV focuses on PHY & MAC and Chapter V on coexistenceissues. Finally, the conclusion is given in Chapter VI.

II. SYSTEM REQUIREMENTS

By the TC SmartBAN, several use cases which are highlybenefitting SmartBAN approach are defined. The applicationareas are divided for several categories, such as healthcare,medical, elderly care, fitness and sport [2]. Each of thesecategories has different sets of their own applications whichgive various requirements for the SmartBAN protocols.

The standard is supporting both on-body links and links to

implanted devices. Within the end-to-end system, SmartBANdevices can be connected using, e.g., Bluetooth, Bluetooth LowEnergy and other existing radio standards. Thus, SmartBANconcept is based on the heterogeneous multi-radio approach, aspresented in Fig. 1 [2]. A SmartBAN hub can also act as arelay or bridge between devices operating with different radiostandards.

III. DATA REPRESENTATION

During the work, a high level descriptions andspecifications of infrastructure and mechanisms providingsolutions for heterogeneity and interoperability management inSmartBANs are defined. The scope is mainly to cover from the

networking level up to the service and application levels. Theexpected solutions will mainly concern:

1) The specification and the formalization of aSmartBAN unified data representation formats, semantic opendata model and corresponding ontology. This unifieddescription model will, in particular, be provided withextensible semantic metadata for SmartBAN entities andrelated data (including in particular sensor/actuator/relay/coordinator/Hub descriptions and sensed/measured data), aswell as for key monitoring and control information.

2) The specification of a standardized end-to-endarchitecture (up to the remote control and monitoring serversof, e.g., caregivers or healthcare centers) for SmartBANentities’ generic interactions, data access, control andmonitoring, irrespective of whatever lower layers and radiotechnologies are used. This architecture will be fully relying onthe SmartBAN semantic data model, which will also enable theneighboring BAN discovery, BAN interworking functionalitiesand smart control. The SmartBAN end-to-end architecturedesign will also imply the specification and the formalizationof SmartBAN service ontology, the associated standardizedservice level enablers and application programming interfaces

(API). The description and the specification of a standardizedinfrastructure for SmartBAN entities (e.g., sensors andactuators) interactions, data access and monitoring, irrespectiveof whatever lower layers and radio technologies are utilizedunderneath. On the service and application sides, standardizedAPI for secure interaction and access to SmartBANdata/entities (data transfer and sharing mechanisms included) isin particular interest.

The SmartBAN semantic open data model and ontologyhave already been fully specified, formalized and pre-qualifiedin [3,4] and will only be summarized in the next sub-section.The SmartBAN standardized end-to-end architecture will beaddressed in later dedicated Work Item of TC SmartBAN and

is therefore not presented in this paper.SmartBAN semantic open data model

The proposed data model is divided into three main parts:BAN (SmartBAN or BAN cluster), Nodes (i.e., Hub, relay,sensors and actuators), Process and Measurements. Fig. 2summarizes the main classes introduced for the SmartBANBAN part.

A SmartBAN is identified by its BANID that should beunique and accessible by any authorized user. It is composed ofa certain number of nodes (BAN’s density) deployed on or

Fig. 1. Future multi-radio SmartBAN concept.


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inside a human body. Thus, SmartBAN location, whenavailable and needed, should be given relatively to the one ofthe body can refer to (generally the location of the patientwearing the BAN and acting as the contact point for this BAN).SmartBAN nodes are distributed based on a physical topologyand are exchanging data through network links that are alsohandled and described within the data model. Finally, aSmartBAN is used for monitoring specific phenomena (burned

calories during exercises, glucose level, etc.) belonging to aspecific domain of application (healthcare, telemedicine,assisted living, sport training, pervasive computing, safety andemergency, etc.). All the aforementioned attributes are inparticular associated to the BAN class of the SmartBAN modelsummarized in Fig. 2. Fig. 3 summarizes the main classes ofthe SmartBAN node and process/measurements model.

Fig. 2. Main classes of SmartBAN BAN part.

Fig. 3. Main classes of SmartBAN Nodes, Process and Measurements parts.

As depicted in Fig. 3, each node:

• Is identified by a Node ID (e.g., its MAC address, its serialnumber, any other unique descriptor),

• Is used for a certain process (e.g., temperature, bloodpressure, insulin regulation, and so on) that is associated tomeasurement data provided with a given format andconstraints (e.g., validity, operating, security, reliability,etc.),

• Evaluates measurements (mainly associated with the sensedvalue),

• Has only one node’s type (associated with functioningmode, energy source and low energy constraints, resourceslike processor and memory, and interface),

• And has finally an interface for data transmission interfaces(e.g., SmartBAN PHY/MAC, Bluetooth LE, IEEE802.15.6, etc.).

IV. PHY AND MAC

In this section, a brief introduction to SmartBAN PHY &MAC protocols is given. A more detailed description of theprotocols are presented in [5, 6] for PHY layer specifications,

and in [7, 8] for MAC layer specifications. The key concept ofSmartBAN PHY & MAC solution is a low-power and low-complexity design, especially on the node side. A one-hop startopology with a Hub acting as a coordinator is defined. Due tothe higher power capability Hub has, it can have morefunctions to operate.

A. Ultra-Low power PHY

The frequency spectrum of SmartBAN operation at the firststage is, but not limited, at the unregulated frequency band forIndustrial, Scientific and Medical (ISM) applications. Inparticular, the ISM band of 2.401-2.481 GHz is identified forthe operation of the first version of SmartBAN [5,6].

The SmartBAN concept is utilizing two different channels:a control channel, where a Hub broadcasts a control beaconincluding network parameters, and a data channel, where data,management and control transmissions take place. With 2 MHzchannels, the SmartBAN has 3 control channels and 37 datachannels, from which the optimal channels can be selectedbased on the interference and other possible restrictions. Thetwo-channel concept provides fast channel acquisition and easy

Hub to Hub communication, which is not included, e.g., in [1].This will increase the usability of the SmartBAN if comparedto existing WBAN standards.

The basic unit of data transmission of the PHY is thePhysical-Layer Protocol Data Unit (PPDU), which isdescribed in Fig. 4. It consist of a 16-bit Preamble, a 40-bitPLCP Header and a Physical-Layer Service Data Unit(PSDU). As described in Fig. 4, PSDU is a MAC ProtocolData Unit (MPDU), which is further divided into threedifferent parts. PLCP Header is protected with a systematicBCH code, whereas for MPDU BCH coding is optional.

In addition to Forward Error Control (FEC) provided by

systematic BCH coding, repetition coding can be implementedto reduce errors. Two repetition schemes shall be supported, 2-repetition, repeating the entire PPDU 2 times, and 4-repetition,repeating the entire PPDU 4 times. Data scrambling is alsosupported.

Fig. 4. Physical-Layer Protocol Data Unit (PPDU) structure.

B. Low complexity MAC

Connection procedure to the network is started bymonitoring the control channel. After receiving a control


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beacon, a node is able to switch to the data channel andinitialize a connection to the Hub.

Data channel is divided into Inter-Beacon Intervals. In thebeginning of each Inter-Beacon Interval, the Hub sends abeacon, and the remainder of the Inter-Beacon Interval isdivided into three parts: Scheduled Access Period, Control andManagement (C/M) period, and Inactive Period. Each of theperiods is further divided into time slots of equal size.

Data transmissions are carried out mainly in the ScheduledAccess Period, in which the time slots are allocated by the Hubbased on node’s requests and available resources.Transmissions in the Scheduled Access Period are contentionfree, as in TDMA (time division multiple access) basedprotocols. C/M period is utilized for transmitting managementframes by employing Slotted-Aloha channel accessmechanism. C/M period can also be used for data transmissionwhen sufficient resources have not been allocated in theScheduled Access Period for node’s/Hub’s purpose.

In addition to basic channel access mechanisms describedabove, an alternative Multi-use Channel Access (MCA) mode

is defined. It utilizes a unique time slot structure, which enablesthe transmission of highest priority (i.e., emergency) packets inevery time slot thus guaranteeing very-low latency for time-critical applications. In addition, MCA enables the utilizationof scheduled but unused time slots, and therefore the channelutilization is increased. These features are not supported, e.g.,by [1]. For detailed information on the features of theSmartBAN MAC, reader is directed to [7,8].

V.

COEXISTENCE AND CHANNEL OCCUPANCY

Unlicensed frequency bands are used by a large variety ofdevices, including wireless local area network (WLAN) andBluetooth devices. As a result, severe interference in the ISM

band is expected.

The scope of this study in TC SmartBAN is to analyze thecoexistence of several wireless devices operating around the2.4 GHz ISM band. The goal is to develop a stochastic modelto evaluate coexistence in an arbitrary operational environment.To develop a model, empirical measurements were carried outto estimate parameters and to substantiate the analytical model.By using the model, coexistence is evaluated based on thevariations in the operational environment which takes intoaccount the uncertainty in an installation’s location and in theinterfering traffic. This evaluation points to potential troublespots and helps in determining strategies for alleviating them.In addition, the model can be used to evaluate techniques for

mitigating interference and assist in optimizing the coexistenceof different radio technologies operating in the same space.

Measurement campaigns have been carried out in two EUcountries and others are still planned. The scope of themeasurements is to collect long-interval data on the spectrumutilization in several environments, in particular in hospital,home and office. In the future, wearable or implantableSmartBAN devices are expected to operate more frequently inthese specific types of environment. In the measurements, thesamples received by the spectrum analyzer are recorded, atleast one week long, in order to get statistically reliable

information describing the spectrum utilization in differentdays.

The impact of the interference is evaluated by three types ofoccupancy metrics which are calculated from the measureddata: channel occupancy (CO), frequency band occupancy(FBO) and spectrum resource occupancy (SRO) [9]. Thesemetrics allow to realize which is the intensity of theinterference, its spreading over time and frequency, the mostoccupied hours per environment, the most occupiedfrequencies, the nature of the interference (bursty orcontinuous), etc. Fig. 5 explains the parameters to be squeezedfrom the measurement data.

In order to come up with a stochastic model of theinterference, other parameters are derived and studied. Inparticular, the most interesting ones are dimensions of theclusters, inter-arrival time of the clusters and amplitudeoscillation inside each cluster. Distributions of these stochasticparameters are investigated and derived. Once the stochasticmodel is ready, it can be used to simulate the impact of theinterference of each specific environment on desired wirelesssystem. This is a useful task in order to evaluate the overallperformance of SmartBAN devices operating in the ISM band,and, in addition, to figure out if more effort is needed tomitigate the interference. Different methods can be introducedto face the interference, such as cognitive approach (sense andswitch to less occupied frequency band).

The channel occupancy results based on the work carriedout by TC SmartBAN are presented, e.g., in [10-13].

Fig. 5. Interference clusters.

VI. CONCLUSION

In this paper, an overview of the ETSI TC SmartBANactivities and the proposed standard are given. The SmartBANis targeted for smart body area network to support wireless datatransmission related to human’s physiological data delivery.

Two-channel approach (data and control) combined withefficient PHY and MAC layers’ protocols are forming a basefor a low complexity and low energy solution to offer reliabletransmission media around a human body.

ACKNOWLEDGMENT

The main contributors for the ETSI TC SmartBAN areCentre Suisse d'Electronique et de Microtechnique (CH),Toshiba Research Europe Ltd (UK), University of Oulu (FI),Consorzio Nazionale Interuniversitario per leTelecomunicazioni (IT) and Telecom Sudparis (FR). In


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addition, several companies have been involved in theSmartBAN process. The authors would like to thank all thecontributors and ETSI Secretariat.

REFERENCES

[1] IEEE Standard for local and metropolitan area networks - Part 15.6:Wireless Body Area Network, IEEE Computer Society, IEEE Std.802.15.6-2012, NY, USA.

[2] ETSI TC SmartBAN, “Smart Body Area Networks (SmartBAN);System Level Description and Requirements”,SMARTBAN(14)006009.

[3] ETSI TC SmartBAN, “Smart Body Area Networks (SmartBAN);SmartBAN unified data representation formats, semantic and open datamodel”, TS DTS/SmartBAN-009V1.0.0, Nov 2014.

[4] L. Nachabé Ismail, M. Girod-Genet, B. El-Hassan, F. Aro, “ApplyingOntology to WBAN for mobile application in the context of sportexcersises”, the 9th International Conference on Body Area Networks,Sep 29 - Oct 1, 2014, London, UK.

[5] ETSI TC SmartBAN, “Smart Body Area Networks (SmartBAN);Enhanced Ultra-Low Power PHY”, TS DTS/SmartBAN(14)006002,Nov 2014.

[6] W.H. Chin, H. Tanaka, T. Nakanishi, T. Paso, M. Hämäläinen, ”AnOverview of ETSI TC SmartBAN’s Ultra Low Power Physical Layer”,

the 9th International Symposium on Medical Information andCommunication Technology, 24 - 26.3.2015, Kamakura, Japan.

[7] ETSI TC SmartBAN, “Smart Body Area Networks (SmartBAN); LowComplexity Medium Access Control (MAC)”, TS DTS/SmartBAN(14)006001r5, Dec 2014.

[8] T. Paso, H. Tanaka, M. Hämäläinen, W.H. Chin, R. Matsuo, S.Subramani, J. Haapola, ”An Overview of ETSI TC SmartBAN MACProtocol”, the 9th International Symposium on Medical Information andCommunication Technology, 24 - 26.3.2015, Kamakura, Japan.

[9] J.J. Lehtomäki, R. Vuohtoniemi, K. Umebayashi, J.-P. Mäkelä, “Energydetection based estimation of channel occupancy rate with adaptivenoise estimation”, IEICE Transactions on Communications, 2012.

[10] L. Mucchi, A. Carpini, T. Kumpuniemi, M. Hämäläinen, J. Iinatti,“Evaluation of the Aggregate Interference in Hospital ISM Band”, the

9th International Conference on Body Area Networks, Sep 29 - Oct 1,2014, London, UK.

[11] M.H. Virk, R. Vuohtoniemi, M. Hämäläinen, J.-P. Mäkelä, J. Iinatti,“Spectrum Occupancy Evaluations at 2.35-2.50 GHz ISM Band in aHospital Environment”, the 9th International Conference on Body AreaNetworks, Sep 29 - Oct 1, 2014, London, UK.

[12] M.H. Virk, R. Vuohtoniemi, M. Hämäläinen, J. Iinatti, J.-P. Mäkelä,”On Spectrum Occupancy Evaluations From the Standpoint of BodyArea Networks in ISM Band”, the 9th International Symposium onMedical Information and Communication Technology, 24 - 26.3.2015,Kamakura, Japan.

[13] L. Mucchi, A. Carpini, T. D’Anna, M.H. Virk, R. Vuohtoniemi, M.Hamalainen, J. Iinatti, “Threshold Setting for the Evaluation of theAggregate Interference in ISM Band in Hospital Environments”, the 9thInternational Symposium on Medical Information and CommunicationTechnology, 24 - 26.3.2015, Kamakura, Japan.


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