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A Novel Approach to implement Fast Flexible Model for secured communication with using ISO/IEEE 11073 Standards for PHDsHarshal Dalal1, Sanjaykumar L. Patil1, Uttam Chaskar11 College of Engineering, Pune (COEP), India, harshal.dalal92@Abstract—this paper presents implementation of Protocol Buffer (Google’s Developers) with Nanopb using ISO 11073/IEEE 1073 standards for personal health devices (PHDs). The ISO/IEEE 11073 standards family enables safety, security, en-vironmental protection and health practices. Approached model improves conventional methodology of standards with simpler, faster and efficient mechanism. Communication between PHDs (Agents) and Computers/Smart devices (Managers) becomes reliable with the use of standards but with using protocol buffer, representation of the system saves time, memory and complex-ity with secured communication. Non-invasive blood pressure monitoring device (NIBP) has developed with implementation of Fast Flexible Model with using ISO/IEEE 11073 standards. Changes in the architecture of standards are capable to achieve interoperability, real-time communications and efficient data exchange between NIBP device and mobile application. This paper gives a methodology of successful implementation with proposed model for part-10407 of ISO/IEEE 11073 standards family for non-invasive Blood Pressure monitoring.Key words—ISO/IEEE 11073, Protocol Buffer, Nanopb, Secu-rity, Health informatics, PHDsFig. 1. System Design with Protocol Buffer313690-205740000are automated mechanisms to serialize structured data with multiple language and platform compatibility[2].I. INTRODUCTIONII. HARDWARE IMPLEMENTATIONTele-monitoring in medical is growing as an efficient, time and money savings solutions[5]. The concept of tele-monitoring established with efficient exchange of data without any human interference . Security and interoperability in real time communication with high flexibility of data exchange is a prior need[4]. Therefore, plug and play interface should be included to provide interoperability and flexibility between PHDs and Gateways. Major disadvantages in the absence of the communication standards are data loss occurs at some-times, data can be manipulated by external factors, manual procedures can be slow, aperiodic in different environmental settings. To overcome the above mentioned factors, System must be automatic, fast, low cost and reliable[1]. With different commercial standardized products, it should be possible to operate agents and managers with plug and play interface. Though, level of communication gets improved but still there is a chance to save time and memory from bulky software. Hence, proposed model has developed for ISO/IEEE 11073 standards to make it more flexible, secure, and efficient. Now, Google has come up with facilities to develop system in more stable way with using protocol buffer. Protocol buffersNon-invasive blood pressure monitor (NIBP) has developed with oscillometric algorithm with systolic pressure, diastolic pressure, mean arterial pressure (MAP), pulse rate, battery sta-tus features are implemented in the system setup with accuracy of 4 mmHg calibrated with FLUKE vital sign simulator[8]. Setup has freescale’s pressure sensor (MPX2050) which is connected to patients cuff to provide equivalent voltage with respect to cuff pressure. Signal from the sensor is given to Analog signal conditioning circuit to get indirect pulsation of blood pressure. This data is input to microcontroller for digital filtering and output data in terms of systolic, diastolic, MAP will be output to other devices. Motor and valve both are controlled using MSP430 TIs microcontroller to automate inflation/deflation of cuff pressure. Output data with standard Nanopb Protocol Buffer ANSI-C library format will be given to further communication. In communication Bluetooth device is used for wireless connectivity. Mobile application works as manager to handle the communication with agent and output data gets high security, flexibility and fast response with using protocol buffer.‘ Fig. 2. (A) Conventional Model of ISO/IEEE 11073 using ASN.1 (B) Approached model using Google’s Protocol Buffer for ISO/IEEE 11073III. SOFTWARE FLOWIn personal health care devices (PHDs) like, blood pressure monitoring device with ISO/IEEE 11073 compliance standards ensures quality of health with safety of medical records of patients[6]. Conventional methodology of the standard de-scribed in the figure 2(A), proposed model replacing ASN.1 nomenclature described in figure 2(B). To understand the protocol buffer and its operation, software flow is divided in two sections, complete system standard model and proposed model with replacement of ASN.1 architecture with Protocol Buffer. Here, the complete standard model profile which is necessarily required to cover both the sections for end to end communications.A. ISO/IEEE 11073 standards and its implementation method-ologyIEEE 11073-20601 established from object oriented system in which part 10407 is dedicated to non-invasive Blood Pressure Monitoring device(NIBP). Primary components of the complete system model are: domain information model, service model and communication model.1) Domain information model (DIM): DIM provides infor-mation regarding device and physiological data sets of objects. These objects and their attributes are used to represent control-ling behavior and providing event report through specific agent which can communicate data to manager. Key objects in DIM are medical device system (MDS) objects, numeric objects, real-time sample array (RT-SA) objects, enumeration objects, PM-store objects and scanner objects. ECG/PPG signal is continuous and objects in DIM are designed such that real time sampling, periodic or episodic scanning and storingFig. 3. System Model313690-265620500can be achieved with RT- SA, scanner and PM-store objects respectively. In the case of blood pressure, there is no need for continuous scanning and real time sampling therefore as shown in Fig. 3, mandatory MDS object with compound numeric and numeric objects are used. Compound numeric object holds data value for all pressures (systolic, diastolic, MAP) and numeric object holds pulse rate data. In the beginning of communication, configuration between agent and manager gets accomplished and information sharing can be done with successful configuration in MDS object.Service model: Service model provides services to ex-change structured data from DIM to agent and manager with the help of GET, SET, Action services and Event Report services. GET and SET services are used by managers to get values from attributes of MDS object and to set specific attribute of agent object. In blood pressure there is no such attribute that can be set but Event Report service is used by agent to convey configuration report as well as measured blood pressure data to the manager. Model manages to pass various messages between PHDs and Gateway. Communication model: In Communication model one or more agents can communicate with single manager with point to point configuration. Transport layer is established between agent and manager with the help of Bluetooth (BLE) device. Also, abstract syntax notation one (ASN.1) converts representation of objects in DIM to a transferable syntax. ASN.1 also provides various types of encoding and decoding technique to encrypt an object in binary message. Here, received message is decrypted to get objects and their data. As shown in figure 4, when a physical connection between both agents and managers gets successfully established, both goes to unassociated state. When manager receives association request from agent, it checks system ID, device configuration ID to get associated with each other. Next, it will go to operating state to exchange the data. In the last, after exchange of data, release request from agent is sent to manager and 93599073152000Fig. 4. Communication modelmanager will respond back. This state can lead to unassociated state again.B. Implementation of Protocol Buffer replacing ASN.1 nomen-clature of standardsWith implementation of the standard, we can achieve in-teroperability and security in communication but efforts, time and RAM requirements make it more impractical to implement it on lower end micro-controller. This drawbacks motivates the need of automated model with Googles protocol buffer. It has language-neutrality, platform-neutrality and support that makes it highly flexible and it is extensively used to implement communication protocol and data storage and structure the data. Protocol buffer has automated mechanism to linearize the structured data which is an advantage to implement with the standards IEEE 1073 and system model becomes simple, robust, generous and time saving[3]. Protocol buffer provides support in java, C++ and python. Next, protocol buffer is ex-tended by Nanopb which is an ANSI-C library for encryption and decryption of message which works on pure C runtime with small code size and small RAM usage. This is how low end microcontroller can also get communication protocol.Nanopb runtime library provide online solution to gen-erate files such as pb.h, encode.h, encode.c, decode.h and decode.c.Here, pb.h is to communicate message, encode.h & encode.c used for encoding message, decode.h & decode.cFig. 5. Communication procedure with unknown/known configuration313690-448627500used for decoding the message. Once domain information gets finished, developer has to define this DIM (Agent/Manager) data into special structured file. This protocol descriptor file is known as .proto file. With the support of protocol buffer, de-veloper can use source code from special auto generated file (C files and header files) to read structured data from data stream or to write structured data into its equivalent stream. Google’s protocol buffer is language independent, as most PHDs are microcontroller based which is programmed in embedded C and gateways like mobile application is programmed in java [4]. This language neutrality feature makes the system very flexible to adopt different platforms.Implementation of IEEE 1073 with nanopb starts with generating .proto files which is structured with various messages according to attributes of different objects in Domain Information Model. For Blood pressure monitoring Device, Bloodpress.proto file is created as shown in the figure 7. Messages like Association Request, Association Response, Medical Device System, Measurement Data etc. created. Each message of protocol buffer has a logical record information containing one or more numbered attributes where each attribute has specific name and particular data types. When structuring of message is completed this .proto file is gets compiled with Google protocol buffer compiler (protoc) to93599073152000Fig. 7. Sample of Source code implementationnanopb references, each and every byte will be transmittedafter encoding is done, this is done to prove additional levelof security is added than ASN.1.IV. CONCLUSIONInteroperability, security and flexibility are major focusedparameters which can be fully achieved with using Nanopb andFig. 6. Sample of .proto fileProtocol Buffer. As the goal is to reduce time, money and com-plexity in the standard ISO 1073/IEEE 11073, proposed modelproduce data access classes.replaces ASN.1 with Protocol Buffer and we implementedthe system model successfully with NIBP device. ASN.1 isEncryption and decryption, both are handled by protocolmore stable and reliable in most of the cases with complexbuffer. In encoding, consider a simple examplestrategies so in future we will try to stable the algorithm withusing complete set of features added into it. Our target is alsomessage association requestto implement communication protocol on portable multi-pararequired unit32 data-proto-ID = 1;monitor where continuous scanning is required.ACKNOWLEDGMENTIn the application data-proto-id is set to 450 and now, serialize the message to output stream. So, Binary will be 111000010 and each byte gets changed and MSB Bit gets set. Now, lower 7 bits of each byte are used to store 2’s complement representation of the number of groups of 7 bits.450 has 2 Bytes like, 0000 0011 1100 0010MSB bit of each byte is dropped to check if you are reached at the end. like,000 0011 100 0010now reverse the two groups of seven bits, and add one MSB bit to upper byte and 0 MSB bit to lower byte. This is how encoding is done through protocol buffer. In this short method, code complexity is decreasing with extra level of security prior to ANS.1 security. Here, Both flexibility and feasibility can be achieved by protocol buffer.If developer compiles Bloodpress.proto with protoc then c file and header file gets generated. C file contains initializer for constant array and header files contains type declaration. However, writing one proto file developer can generate files in C++, JavaNano, python, Ruby etc. These generated files provide accessors as well as methods to serialize whole structure to raw bytes and to parse the complete structure from raw bytes. To get this transformation done a predefined instruction and methods are properly used in main source code.It can be possible to enhance security by using pb encode and pb decode api references of nanopb which is just an extension of protocol buffer. Standardization with use ofWe would like to thank Sofomo Embedded Solutions and team for their kind support and guidance to develop this setup. We are also thankful to the Department of instrumentation & Control, College of Engineering, Pune (COEP) for providing us all the necessary facilities.REFERENCESYao, Jianchu, and Steve Warren. ”Applying the ISO/IEEE 11073 stan-dards to wearable home health monitoring systems.” Journal of clinical monitoring and computing 19.6 (2005): 427-436. Internet Source: Internet Source: Yuksel, Mustafa, and Asuman Dogac. ”Interoperability of medical device information and the clinical applications: an HL7 RMIM based on the ISO/IEEE 11073 DIM.” Information Technology in Biomedicine, IEEE Transactions on15.4 (2011): 557-566. Galarraga, Miguel, et al. ”Telemonitoring systems interoperability chal-lenge: an updated review of the applicability of ISO/IEEE 11073 stan-dards for interoperability in telemonitoring.” Engineering in Medicine and Biology Society, 2007. EMBS 2007. 29th Annual International Conference of the IEEE. IEEE, 2007. Clarke, Malcolm, et al. ”Developing a standard for personal health devices based on 11073.” Engineering in Medicine and Biology Society, 2007. EMBS 2007. 29th Annual International Conference of the IEEE. IEEE, 2007. Park, ChanYong, Joon-Ho Lim, and Soojun Park. ”ISO/IEEE 11073 PHD standardization of legacy healthcare devices for home healthcare services.”Consumer Electronics (ICCE), 2011 IEEE International Con-ference on. IEEE, 2011. Wan, Y., et al. ”Determining which automatic digital blood pressure device performs adequately: a systematic review.” Journal of human hypertension24.7 (2010): 431-438. ................
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