Sudhanshu Tyagi,Sudeep Tanwar,Sumit Kumar Gupta,Neeraj Kumar,and Joel J.P.C.Rodrigues

(1.Department of Electronics and Communication Engineering，J.P.Institute of Enginerring and Technology(JPIET)，Meerut 250002，India; 2.Department of Information Technology，Bharat Institute of Technology，Meerut 250002，India; 3.Department of Electronics and Communication Engineering，Institute of Information&Management Technology(IIMT)，Meerut 250002，India; 4.Department of Computer Science and Engineering，Thapar University，Patiala 147004，India; 5.Instituto de Telecomunicações，University of Beira Interior，Covilhã 6200⁃034，Portugal; 6.University ITMO，Saint⁃Petersburg 197101，Russia)

Selective Cluster⁃Based Temperature Monitoring System for Homogeneous Wireless Sensor Networks

Sudhanshu Tyagi1,Sudeep Tanwar2,Sumit Kumar Gupta3,Neeraj Kumar4,and Joel J.P.C.Rodrigues5,6

(1.Department of Electronics and Communication Engineering，J.P.Institute of Enginerring and Technology(JPIET)，Meerut 250002，India; 2.Department of Information Technology，Bharat Institute of Technology，Meerut 250002，India; 3.Department of Electronics and Communication Engineering，Institute of Information&Management Technology(IIMT)，Meerut 250002，India; 4.Department of Computer Science and Engineering，Thapar University，Patiala 147004，India; 5.Instituto de Telecomunicações，University of Beira Interior，Covilhã 6200⁃034，Portugal; 6.University ITMO，Saint⁃Petersburg 197101，Russia)

Over the past few decades，there has been a revolution in ICT，and this has led to the evolution of wireless sensor networks (WSN)，in particular，wireless body area networks.Such networks comprise a specialized collection of sensor nodes(SNs)that may be deployed randomly in a body area network to collect data from the human body.In a health monitoring system，it may be es⁃sential to maintain constant environmental conditions within a specific area in the hospital.In this paper，we propose a tempera⁃ture⁃monitoring system and describe a case study of a health⁃monitoring system for patents critically ill with the same disease and in the same environment.We propose Enhanced LEACH Selective Cluster(E⁃LEACH⁃SC)routing protocol for monitoring the tem⁃perature of an area in a hospital.We modified existing Selective Cluster LEACH protocol by using a fixed⁃distance⁃based thresh⁃old to divide the coverage region in two subregions.Direct data transmission and selective cluster⁃based data transmission ap⁃proaches were used to provide short⁃range and long⁃distance coverage for the collection of data from the body of ill patients.Ex⁃tensive simulations were run by varying the ratio of node densities of the two subregions in the health⁃monitoring system.Last Node Alive(LNA)，which is a measure of network lifespan，was the parameter for evaluating the performance of the proposed scheme.The simulation results show that the proposed scheme significantly increases network lifespan compared with traditional LEACH and LEACH⁃SC protocols，which by themselves improve the overall performance of the health⁃monitoring system.

network lifespan;sensor node;LEACH;LNA

1 Introduction

A wireless sensor network(WSN)comprises a large number of sensor nodes(SNs)that communicate wirelessly.In a WSN，a sink node collects data from all sensors for further processing.A WSN is considered a multihop network for cluster communication.Fig. 1 shows the schematic of various operations in a WSN.

Each SN has a radio transceiver with internal antenna，a mi⁃crocontroller，a battery，and an electronic circuit for interfac⁃ing with sensors and energy source.Size and cost constrains SNs in terms of their energy consumption(a key issue)，memo⁃ry，computational speed，and communication bandwidth.

The technique used to transmit data from source to sink node is based on an appropriate routing decision，but it is diffi⁃cult to select a routing scheme is energy efficient.

▲Figure 1.Wireless sensor network.

There are a number of protocols for routing in a WSN.These protocols vary from application to application and may be data⁃centric，hierarchical，or based on cluster，location，mobility，QoS，network flow，multiple paths，heterogeneity，or homogene⁃ity[1]，[2].Energy efficiency is the key parameter for WSN routing protocols because the battery power in SNs is limited. Because of the rising cost of e⁃healthcare solutions，wirelessbody area networking(WBAN)has received more attention from researchers and application developers[3].A WBAN is a network of small，intelligent sensors that are attached to cloth⁃ing，stuck directly onto the body，or implanted inside the body for continuous monitoring.These devices can sense，sample，and send the captured data to an associated device，e.g.，a smartphone.Then，this data can be sent via wireless link to a medical team for real⁃time diagnosis.In a body sensor net⁃work，sensors and actuators are used.A sensor detects certain vital signs from the human body，such as blood pressure，heart⁃beat，and body temperature.An actuator performs specific tasks according to data received from sensors or through inter⁃action with a human.The tiny sensors used in a WBAN are en⁃ergy⁃constrained，so energy efficiency is an important research area.We consider a case where the temperature within a hospi⁃tal is monitored and controlled for patients with similar diseas⁃es.The literature shows that clustering is a better mechanism for measurement of unique data.The cluster⁃based routing pro⁃tocol is one of the most interesting research areas in WSN.Low⁃Energy Adaptive Clustering Hierarchy(LEACH)[4]protocol is energy efficient and aggregates data，so it is widely used in WSNs.In this paper，we refer to existing work in[4]and[5] and propose Enhanced Low⁃Energy Adaptive⁃Cluster⁃Based Hierarchical Selective Clustering(E⁃LEACHSC)protocol.This protocol leverages direct communication and cluster⁃based communication，both of which occur over the selective cluster. The authors have used fixed distance between BS and CH for communications.From the literature survey in[2]，a clustering approach involves a minimum of two hops in the transmission of data from source to base station(BS)，even though the dis⁃tance between the source and BS may be very small.Hence，we focus on the energy constraints on an individual SN.The key parameter use to evaluate our proposed protocol is last node alive(LNA).

The remainder of this paper is organized as follows.In sec⁃tion 2，related work and contributions are discussed.In section 3，E⁃LEACH⁃SC routing protocol in described.In section 4，our protocol is simulated in MATLAB，and the performance of our protocol is compared with that of LEACH and LEACH⁃SC，other well⁃known routing protocols.Section 5 concludes the pa⁃per.

2.Related Work and Contributions

2.1 Related Work

WSN has already been used in a wide variety of applica⁃tions，so it is important to establish specialized methodoligies for increasing network lifespan and improving routing.A num⁃ber of proposals have been made to address these issues.

2.1.1 Energy⁃Harvesting Approach

To improve the lifespan of a WSN，extra energy is required. There are different mechanisms by which the overall energy of the network field can be increased.In this section，we consider the concept of harvesting extra energy from the surrounding en⁃vironment.Pei et al.[6]suggest a WSN routing protocol based on local adaptive sampling.The authors harvest energy to im⁃prove the overall network performance.Adaptive sampling is used to adapt the sample mode to current conditions and to monitor energy in real time.Zhang et al.[7]proposed an opti⁃mization algorithm for single clusters and multiple clusters. This algorithm considers the energy⁃harvesting(EH)node as the relay node.The authors determined the weight of the EH node in order to estimate an optimal CH position.Designing an EH node is not easy，and several things need to be presumed. In[6]，the type of EH node used in the proposed work is not discussed.

2.1.2 Application⁃Oriented Approach

The rising cost of healthcare has shifted the focus towards wireless body area networking(WBAN)，which is an emerging area of networking.We have extended the concept of health⁃care monitoring and WBAN to provide e⁃healthcare solutions at cheap rates to end users without compromising quality.J.M. L.P.Caldeira et al.[8]propose using biosensors to monitor temperature within the body.A biosensor is an analytical de⁃vice used for detection in different applications，and it can vary in sensitivity.The authors continuously measured the intra⁃vaginal temperature of hospitalized women and found that the temperature varied for each woman.The study had implica⁃tions for preventing preterm labor，detecting pregnancy con⁃tractions，monitoring ovulation period，determining the effec⁃tiveness of gynecological treatments，and discovering new con⁃traception methods.Ousmane Diallo et al.[9]propose a frame⁃work that combines WBAN with cloud computing and statisti⁃cal modeling in order to maximize energy efficiency and se⁃curely store data received by the sink from body sensors.The authors assume a fixed WBAN topology where the patient in a hospital bed or at home and not in a condition to move.The da⁃ta of every patient is stored in a server at the hospital so that any queries about the patient can be answered.If the patient’s data cannot be found or is insufficient，the query is forwarded to the WBAN so that the required data can be obtained.This scheme enables the retrieval of data that is suitable for real⁃time medical diagnosis and energy⁃efficient processing.The authors of[9]do not take into consideration patient mobility. O.R.E.Pereira et al.[10]propose a BSN mobile solution for biofeedback monitoring on Symbian，Windows Mobile，An⁃droid，and iPhone over SHIMMER platforms.The authors found that the life of a critically ill person can be improved us⁃ing a mobile healthcare system as opposed to a traditional healthcare system.In a mobile healthcare system，data can be collected，visualize，and monitored immediately by a team of doctors，and instant action can be taken.Energy efficiency is significant issue in mobile healthcare system and needs to becarefully considered to improve the overall quality of the sys⁃tem.

2.1.3 Direct Communication

Intanagonwiwat et al.[11]proposed directed diffusion(DD) as a way of constructing the route between SNs and BS.There are four stages in DD，the most important being direct data communication.In DD，SNs that are far from the base station die quickly because of the large transmission distance.This means that some areas have no coverage.However，for small⁃scale networks，DD is a good option.

2.1.4 Cluster⁃Based Homogeneous Network

Heinzelman et al.[4]proposed a low⁃energy adaptive clus⁃tering hierarchy(LEACH)protocol.This protocol is a self⁃orga⁃nizing，adaptive clustering protocol that provides each SN with equal energy.The LEACH protocol is executed in rounds，each of which has two phases:setup and steady state.The steady⁃state phase is extensive compared to the setup phase. In LEACH protocol，the SNs organize themselves into local clusters，and one node，called the cluster head(CH)，is the re⁃sponsible node.The rest of the nodes，called cluster members (CMs)act as ordinary nodes for the respective cluster.To pro⁃long the life of the network，LEACH protocol randomly rotates the high⁃energy CH and performs local data fusion to transmit the data from the CHs to the BS.If the BS is far from the net⁃work，the energy of the CHs is affected because only CHs com⁃municate directly with the BS.This unique feature of LEACH protocol saves overall network energy because CMs do not di⁃rectly communicate with the BS.

For a cluster formation，each SN decides whether or not to become a CH for the current round.This decision is based on the percentage of CHs for the network and the number of times the SN has already been a CH.In this process，every SN has to select a random number between 0 and 1.If the number is less than a threshold，the SN becomes a CH for the current round. The threshold is given by[4]:

where p is the desired percentage of CHs，r is the current round，and G is the set of SNs that have not been CHs in the last 1/p rounds.During round 0，every SN has a probability p of becoming a CH.The SNs that are CHs in round 0 cannot be CHs for the next 1/p rounds.This is necessary to increase the probability of the remaining SNs becoming CHs because now there are fewer SNs that are eligible to become CHs.Using this threshold，each SN will be a CH at some point within 1/p rounds.The main drawback of LEACH protocol is that the en⁃ergy cost is directly proportional to communication distance，i. e.，the energy cost increases as the communication distance in⁃ creases.Therefore，selecting the CMs on the basis of received signal strength increases the communication cost of nodes，which leads to a decrease in energy efficiency across the net⁃work.

Heinzelman et al.[12]proposed a centralized，low⁃energy adaptive clustering hierarchy(LEACH⁃C)protocol.The main difference between LEACH and LEACH⁃C is that LEACH does not take into account the remaining energy of SNs where⁃as LEACH⁃C does.In LEACH⁃C protocol，energy⁃efficient clustering and routing are combined for application⁃specific data aggregation.This increases network lifespan and decreas⁃es data access latency.LEACH⁃C includes a new distributed cluster formation technique that enables self⁃organization for a large numbers of SNs.

In CH election，each node elects itself as the CH at begin⁃ning of time t with probability p.If the expected number of CHs for this round is assumed to be such that N is the total number of nodes in the network，then

The authors of[12]give a mathematical formula for estimat⁃ing the probability that a node becomes a CH after finite num⁃ber of iterations:

where f(t)is the parameter used for the estimation.If the node has been a CH in the most recent rounds then f(t)=1;other⁃wise，f(t)=0.After n Nrounds，each node is expected to be⁃come a CH.From(2)，the SNs that have not become CHs in re⁃cent rounds and have more residual energy than other SNs will become CHs in subsequent rounds.When all the SNs have equal initial energy，the node having minimum residual energy is elected as a CH in the subsequent phases.The remaining ex⁃ecution is same as that of LEACH[4].

Handy et al.[13]proposed a low⁃energy adaptive clustering hierarchy with deterministic cluster head selection(LEACH⁃DCHS)protocol.This protocol is an extended version of LEACH protocol.In LEACH⁃DCHS，the CH is selected by a deterministic component rather than stochastic component. The operation of LEACH⁃DCHS is similar to that of LEACH，where execution is divided into CH election and cluster forma⁃tion.However，the threshold for CH selection is modified and is given by

This threshold is further modified because it is a low⁃value threshold，and it is possible that，after some rounds，the net⁃work may jam.This modified threshold is given by

The advantage of LEACH⁃DCHS is that it improves network lifespan.However，a major drawback of the three protocols dis⁃cussed here is that the respective CMs are selected on the ba⁃sis of the strength of the signal received from the CHs.

To address the issues of LEACH(and its related protocols) and to prolong network lifespan，Jun et al.[7]propose a low⁃en⁃ergy adaptive⁃clustering hierarchical selective cluster(LEACH⁃SC)protocol.In LEACH⁃SC，the process of joining the nodes with the cluster is changed，i.e.，the CH closest to the node it⁃self and the sink node is selected.This increases the lifespan of the network.To minimize the amount of energy used by the network and prolong the network lifespan，the authors of[6] use minimum transmission energy，given by

where k is the number of bits forwarded over distance d，and ETXis the transmitter circuitry dissipation per bit.The distance d is vital to the overall energy cost of the network.Fig.2 shows the generalized architecture used in the proposed scheme.

2.2 Contribution

In[14]-[17]，LEACH and its related protocols were very good cluster⁃based protocols;however，when the BS is located at one corner of the network，all the nodes have better load dis⁃tribution through random selection of CH.SNs opposite the BS die quickly compared to SNs near the BS.We propose En⁃hanced Low⁃Energy Adaptive Selective Cluster Based Hierar⁃chical(E⁃LEACH⁃SC)protocol.This protocol has the advan⁃tage of both direct communication and cluster⁃based communi⁃cation.A fixed⁃distance threshold splits the coverage region in⁃to two parts.Results show that E⁃LEACH⁃SC considerably in⁃creases the lifespan of the network.The network and energy models used for E⁃LEACH⁃SC are same as those in[3]and[6]; the only difference is that the BS in our model is located in a 100×100 m network.

▲Figure 2.Hospital layout.

3 Proposed Approach

In a small network，the DD approach is always better;howev⁃er，in a medium to large network field，a cluster⁃based ap⁃proach is better.E⁃LEACH⁃SC protocol leverages both ap⁃proaches.E⁃LEACH⁃SC used a fixed⁃distance⁃based threshold that divides the network field into two segments.The BS is as⁃sumed to be located at one of the corners of network and is fixed.Therefore，the direct⁃communication approach is used for the region near the BS，and the selective cluster⁃based ap⁃proach is used for the region further away from the BS(Fig.3).

An important issue is how to calculate the fixed⁃distance⁃based threshold.We select the appropriate ratio of node densi⁃ties of the two regions.In LEACH[4]and LEACH⁃SC[7]proto⁃cols，it is assumed that almost no energy is consumed in the formation of cluster.However，in practice，this is not possible. We combine the DD[11]and LEACH⁃SC[7]approaches，to⁃gether and using the fixed⁃distance⁃based threshold，we save the energy of the region over which clustering is not being used.As a consequence，the overall lifespan of the network is increased.

Theorem 1:The energy of an SN can be used efficiently if transmission distance is kept to a minimum.

Proof 1:For proof of Theorem1，we prove the following lem⁃mas.

Lemma 1:SN is part of a cluster if CH is near the midpoint between an SN and BS.

▲Figure 3.Network model.

Proof 1:LEACH is the fundamental cluster⁃based hierarchi⁃cal routing protocol.CMs are selected according to thestrength of the signal received from different CHs.Jun et al.[7] use a different mechanism for selecting CMs[7].From the anal⁃ysis in[7]，lemma 1 can be proved.

Lemma 2:The cost of communication is lower for a selective cluster.

Proof 2:With reference to lemma 1，the distance between the CH and SN is shorter for a LEACH⁃SC than LEACH.The distance between CH and the ith non⁃CH node in a selective cluster is denoteddi-sc，and the distance between CH and the ith non⁃CH node in an ordinary cluster is denoteddi-oc.If dCH-BSis the distance between CH and BS and there are m CMs in a particular region，then average distance for a selec⁃tive cluster will be

and the average distance for an ordinary cluster will be

Therefore，per⁃round energy consumption of a CH in a selec⁃tive cluster is

and per⁃round energy consumption of a CH in an ordinary clus⁃ter is

We observe thatDAvg-OC>DAvg-SC;therefore，lemma 2 is proved，andEr-SC

Lemma 3:A combinational approach is more energy effi⁃cient than an individual approach.

Proof 3:For the proof of lemma 3，refer to the theorem in [18].By considering all lemmas simultaneously，Theorem 1 can be proved.

3.1 Execution of E-LEACH-SC

The energy needed in cluster⁃based communication is high⁃er than that needed for direct communication if the distance be⁃tween the SN and BS is sufficiently smaller than the distance between the SN and CH and the distance between the CH and BS.Fig.4 shows the round⁃wise execution of our scheme.

3.2 Pseudo Code of E-LEACH-SC

Algorithm 1 shows the pseudo code for our proposed scheme.

▲Figure 4.Energy mode flow of E⁃LEACH⁃SCl.

Algorithm 1.E-LEACH-SC:Enhanced LEACH Selective Cluster

All input parameters are initialized in the very first step.On selected node densities，partitions can be formed using an esti⁃mated fixed⁃distance⁃based threshold.We have already as⁃sumed that the network model is homogeneous;hence，all SNs are distributed uniformly over the area of investigation.The SNs of region one communicates directly with the BS.In regiontwo，selective⁃cluster⁃based communication is used(Algorithm 1，steps 11 to 23).

4 Performance Evaluation

We use a first⁃order radio model to simulate LEACH[4]，LEACH⁃SC[7]and E⁃LEACH⁃SC.The parameters used for this simulation are the same as those in[4]，[7].To determine the performance of the E⁃LEACH⁃SC protocol，we had simulat⁃ed a homogeneous clustered WSN in a 100×100 m2field.The total number of SNs is 100，and these SNs are uniformly dis⁃tributed over the network.All the SNs are stationary.The mes⁃sage for data packet transmission is 4000 bits.The key parame⁃ters for determining the performance of the E⁃LEACH⁃SC pro⁃tocol are network lifespan increase and system stability.LNA is used to observe the abovementioned issues for different ini⁃tial energy values.Fig.5 shows that the E⁃LEACH⁃SC proto⁃col significantly improves system lifespan compared to the LEACH and LEACH⁃SC protocols.

Fig.6 shows the node densities of two regions with different initial energy levels.The results validate the selection of a fixed⁃distance⁃based threshold for splitting the network into two regions.In this case，we also use LNA as the measuring pa⁃rameter.

Fig.7 shows network stability for LEACH，LEACH⁃SC and E⁃LEACH⁃SC protocols for different initial energy levels.The average number of rounds for fifteen iterations in LEACH and LEACH⁃SC is less than that for E⁃LEACH⁃SC.Looking at LNA performance，we observe that our proposed protocol is more stable than the LEACH and LEACH⁃SC protocols.

5 Conclusion

WSNs have been used in a large number of medical and healthcare applications.Increasing the lifespan of SNs in⁃creases the lifespan and stability of the entire WSN.In this pa⁃per，we have proposed Enhanced Low⁃Energy Adaptive Selec⁃tive⁃Cluster⁃based Hierarchical(E⁃LEACH⁃SC)protocol for WSN.The E⁃LEACH⁃SC protocol increases system stability，is easy to implement，and extends the lifespan of the network. Our protocol uses selective⁃cluster⁃based communication as well as direct communication between nodes and BS on the ba⁃sis of a fixed⁃distance⁃based threshold.Simulations show that E⁃LEACH⁃SC increase the lifespan of the network and provides good stability compared with LEACH and LEACH⁃SC for the same energy level.In the future，we intend to compare E⁃LEACH⁃SC with other protocols and using additional parame⁃ters.Security aspects of the current scheme will also be ex⁃plored.

Acknowledgements

▲Figure 5.Network lifespan as LNA for LEACH,LEACH⁃SC and E⁃LEACH⁃SC at initial energy levels a)E0=0.25J,b)E0=0.5J, and c)E0=1.0J.

This work has been partially supported by Instituto de Tele⁃comunicações，Next Generation Networks and Applications Group(NetGNA)，Covilhã Delegation，by Government of Rus⁃sian Federation，Grant 074⁃U01，and by National Funding from the FCT⁃Fundação para a Ciência e Tecnologia through the Pest⁃OE/EEI/LA0008/2013 Project.

▲Figure 6.Node densities of two regions for ELEACH⁃SC at initial energy levels a)E0=0.25 J,b)E0=0.5 J,and c)E0=1.0 J.

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Biographiesphies

Sudhanshu Tyagi(sudhanshutyagi123@gmail.com)is an associate professor in the Department of Electronics and Communication Engineering，J.P.Institute of Engineering and Technology，India.He received his BEng degree in electronics and telecommunication from North Maharashtra University，India，in 2000.He received his MTech(Hons) degree in electronics and communication engineering from National Institute of Technology，India，in 2005.He is currently pursuing his PhD in electronics and communication engineering from Mewar University，India.He has authored or co⁃authored six papers in prestigious peer⁃reviewed journals and conference proceedings.He is on the editorial boards of leading international journals，such as International Journal of Ad⁃Hoc and Ubiquitous Computing，Inderscience，and Journal of the Franklin Institute.His research in⁃terests include lifetime enhancement of homogeneous and heterogeneous WSNs.He is a member of IEEE and IAENG.

Sudeep Tanwar(sudeeptanwar149@gmail.com)is an assistant professor in the Department of Information Technology，Bharat Institute of Technology，India.He received his BTech degree in computer science from Kurukshetra University，India，in 2002.He received his MTech(Hons)degree in information technology from Guru Gobing Singh Inder⁃prastha University，India，in 2009.Since 2010，he has been pursuing his PhD with specialization in wireless sensor network and works under the supervision of Dr Neeraj Ku⁃mar of Thapar University，India.He is member of the Computer Society of India，associate member of the Indian Society for Telecommunication Engineers，member of the Inter⁃national Association of Engineers，and a member of the Computer Science Teachers Association，USA.He has authored two papers in peer⁃reviewed international journal and conference proceedings.

Sumit Kumar Gupta(skgupta123@gmail.com)is currently working as an assistant professor in the Department of Electronics and Communication Engineering，IIMT Engineer⁃ing College，India.He received his BTech degree in electronic and communication engineering from Chaudhary Charan Singh University，India，in 2002.He is pursuing his MTech degree in electronic and communication engineering from Uttrakhand Technical University，India.He has eight years industry experience in the operations and custom⁃er support with Tata Sky，Reliance Big TV，and Videocon D2h.He has authored research papers that have been published in high⁃quality national and international journals and conferences proceedings.

Neeraj Kumar(neeraj.kumar@thapar.edu)is an associate professor in the School of Computer Science and Engineering，Shri Mata Vaishno Devi University，India.He received his PhD in computer science and engineering from Shri Mata Vaishno Devi University，India，and thereafter worked as a postdoctoral fellow in the UK.He has authored or coau⁃thored more than 70 paper in peer⁃reviewed journals and conferences proceedings.His research is focused on mobile computing，parallel/distributed computing，multiagent sys⁃tems，service⁃oriented computing，and routing and security in wireless adhoc，sensor and mesh networks.He leads the Mobile Computing and Distributed System Research Group.Prior to joining Shri Mata Vaishno Devi University，he worked with HEC Jagadhri and MMEC Mullana India.He has been invited to speak at various IEEE international conferences in India and abroad.He has organized various special sessions in international conferences in his area of expertise in India and abroad.He is a member of the Technical Program Committee of various IEEE⁃sponsored conferences in India and abroad.He is also on the editorial boards of various international journals.He has been the guest editor of six special issues of international journals.He is senior member of ACM，ACEEE and IACSIT.

Joel J.P.C.Rodrigues(joeljr@ieee.org)is a professor in the Department of Informatics，University of Beira Interior，Portugal.He is also a researcher at the Instituto de Teleco⁃municações，Portugal.He received his PhD and MSc degrees in informatics engineering from the University of Beira Interior.He received his five⁃year BSc degree(licentiate) in informatics engineering from the University of Coimbra，Portugal.His main research interests are vehicular communications，sensor networks，eHealth，eLearning，mobile and ubiquitous computing，and cloud technologies.He is the leader of the NetGNA Research Group，chair of the IEEE ComSoc Technical Committee on eHealth，past chair of the IEEE ComSoc Technical Committee on Communications Software，Member Representative of the IEEE Communications Society on the IEEE Biometrics Council，Steering Committee member of the IEEE Life Sciences Technical Community，and officer of the IEEE 1907.1 standard.He is the editor⁃in⁃chief of the International Journal on E⁃Health and Medical Communications and Recent Advances in Communications and Networking Technology.He is also on the editorial board member of several other journals. He has been the guest editor for a number of journals and has been general chair and TPC chair of many international conferences.He has authored or coauthored more than 350 papers in refereed international journals and conferences proceedings.He has also written a book and holds two patents.He was awarded the Outstanding Leadership Award at IEEE GLOBECOM 2010 as the CSSMA Symposium co⁃chair and has won several other best⁃paper awards.He is a licensed professional engineer，a member of the In⁃ternet Society，an IARIA fellow，and a senior member of ACM and IEEE.

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2014⁃04⁃21

10.3939/j.issn.1673-5188.2014.03.003

http://www.cnki.net/kcms/detail/34.1294.TN.20140829.1544.003.html，published online 29 August，2014