nowadays , various personal health devices ( phds ) are released on a continual basis in recognition of the necessity for healthcare technologies at home . a phd is a device that measures data on the health of its user , for instance , a pulse oximeter , activity monitor , or medication reminder . among the various phds , the pulse oximeter , which measures pulse oximetry data ( e.g. , saturation of peripheral oxygen ( spo2 ) and pulse rate ) , has become one of the most important phds for early diagnosis of heart disease [ 1 , 2 ] . however , some of the existing pulse oximeters are not equipped with communication capabilities , and consequently , the continuous monitoring of patient health is restricted . moreover , even though certain oximeters have been built as network models , they focus on exchanging only pulse oximetry data and they do not provide sufficient device management functions . meanwhile , in a situation , where networked phds are being applied to various u - health services , the standardization of diverse phds is very important to guarantee interoperability between u - health services [ 3 , 4 ] . as a result , iso / ieee 11073   was proposed to define how personal health data should be exchanged between a phd and a monitor and what format should be used for the data . despite the iso / ieee 11073 committee efforts to standardize various phds , many manufacturers of phds for u - health service providers still use their own protocols , and consequently their phds can not be regarded as interoperable . this causes increases in maintenance costs and prevents an integrated u - health service . in this paper the proposed pulse oximeter measures a patient 's pulse oximetry data and transmits the data to the personal monitoring server . for the proposed system to support remote monitoring and management functions , we implement a phd agent and manager on the basis of our previous design study . the phd agent is placed in the pulse oximeter , and the phd manager is placed in the personal monitoring server . the phd agent converts pulse oximetry data and operational errors that occur in the pulse oximeter to an iso / ieee 11073 message format and transmits them to the personal monitoring server . in the proposed system , the pulse oximeter measures spo2 and pulse rate and detects four operational errors : sensor_disconnected , sensor_off , signal_non - detected , and signal_inadequate . the phd manager extracts the pulse oximetry data and operational errors from the received messages . it also manages two components of the system configuration of the pulse oximeter : the thresholds for spo2 and pulse rate and measurement targets . we verify that the proposed pulse oximetry system operates efficiently and that it is appropriate for monitoring and managing a pulse oximeter in real time ; the average response time for transmitting pulse oximetry data or errors is 251  ms . the rest of this paper is organized as follows : section 2 introduces the iso / ieee 11073 standard as background information . iso / ieee 11073 was proposed on may 2006 , to guarantee interoperability between various phds . it specifies how personal health data should be exchanged between a phd and a monitor and what format should be used for the data . the 11073 - 20601 optimized exchange protocol   was proposed to define the communication procedure and interoperable transmission format . , an agent sends an association request message including association information ( e.g. , system i d and configuration i d ) to a manager to establish a session . the manager analyzes the message and checks the configuration of the agent . if the manager can recognize the configuration , the manager responds with an  accepted  parameter ( i.e. , the association was accepted ) . in this case , the operation phase is initiated . alternatively , if the manager does not recognize the configuration , the manager responds with an  accepted - unknown - config parameter ( i.e. , the association was accepted but the configuration needs transmitted ) . in this case , the configuration phase is initiated . configuration phase . during this phase , the agent sends its configuration to the manager . the manager stores the configuration and responds with an  accepted  parameter to prompt the agent into the operation phase . the personal health data are transmitted periodically or whenever the agent takes health data from a phd . in contrast , device information is transmitted at the request of the manager , which sends a if the agent or manager does not have any more messages to transfer , this phase is initiated to release the established session . during this phase , an agent sends an association request message including association information ( e.g. , system i d and configuration i d ) to a manager to establish a session . if the manager can recognize the configuration , the manager responds with an  accepted  parameter ( i.e. , the association was accepted ) . in this case if the manager does not recognize the configuration , the manager responds with an  accepted - unknown - config parameter ( i.e. , the association was accepted but the configuration needs transmitted ) . in this case , the configuration phase is initiated .   configuration phase . during this phase , the agent sends its configuration to the manager . the manager stores the configuration and responds with an  accepted  parameter to prompt the agent into the operation phase .   operation phase . during this phase , the personal health data are transmitted periodically or whenever the agent takes health data from a phd . in contrast , device information is transmitted at the request of the manager , which sends a if the agent or manager does not have any more messages to transfer , this phase is initiated to release the established session . during this phase , the iso / ieee 11073 standard also specifies device specialization protocols considering the characteristics of each phd , such as 11073 - 10404 ( pulse oximeter ) , 11073 - 10407 ( blood pressure monitor ) , 11073 - 10408 ( thermometer ) , and 11073 - 10417 ( glucose meter ) . each specialization protocol details how a phd works and acts as a description for creating a specific type of agent .   among the protocols , this protocol defines objects to represent data that are measured or estimated by pulse oximeters ( e.g. , spo2 , pulse rate , and pulsatility ) . of these , figure 2 depicts the standard messages for transmitting spo2 and pulse rate . despite the iso / ieee 11073 committee efforts to standardize various phds , many existing phds are nonstandard . many manufacturers of phds for u - health service providers still use their own protocols , and consequently their phds can not be regarded as interoperable . the proposed pulse oximeter measures a patient 's pulse oximetry data and transmits the data to the personal monitoring server . for the proposed system to support remote monitoring and management functions , we implement a phd agent and manager on the basis of our previous design study . the phd agent is placed in the pulse oximeter , and the phd manager is placed in the personal monitoring server . the phd agent converts pulse oximetry data and operational errors that occur in the pulse oximeter to an iso / ieee 11073 message format and transmits them to the personal monitoring server . the phd manager extracts the pulse oximetry data and operational errors from the received messages . this measures spo2 and pulse rate using an infrared led , a red led , and a light sensor photo ( pin ) diode . infrared light and red light are passed through the user 's finger the pin diode . this extracts pulse oximetry data , errors , and system configurations from the memory of pulse oximeters . this extracts pulse oximetry data , errors , and system configurations from the memory of pulse oximeters . the processes for converting pulse oximetry data into an 11073 message are shown in figure 4 . the stored pulse oximetry data are extracted and converted into an 11073 message by the memory handler and message handler of the phd agent . the values of spo2 and pulse rate from the memory are inserted into  basic - nu - observed - value  fields and the measured time is inserted into  absolute - time - stamp  fields . the values of  obj - handle  are assigned as 1 and 10 for spo2 and pulse rate , respectively . the personal monitoring server analyzes , collects , and displays the pulse oximetry data and operational errors sent by the pulse oximeter . the architecture of the phd manager placed in the personal monitoring server is similar to that of the phd agent except for a user interface module . phds are usually small , with limited memory and lcds , so a method that measures a user 's health data on a phd but collects and displays those on a device that has better performance is more efficient . in this section , we present the results of the implementation and evaluation of the pulse oximetry system . the pulse oximetry system is comprised of a networked pulse oximeter and personal monitoring server . this prototype uses the finger - type spo2 sensor obtained from apk technology and is loaded with atmega 128 - 16ac mcu and a bluegiga wt12 bluetooth module . in the proposed system , the pulse oximeter measures spo2 and pulse rate using the finger - type spo2 sensor and stores the measured pulse oximetry data in memory . the phd agent within the pulse oximeter extracts the stored pulse oximetry data and detects four operational errors : sensor_disconnected , sensor_off , signal_non - detected , and signal_inadequate . if an error occurs in the pulse oximeter , the corresponding code is inserted into  enum - observed - value - basic - bit - str  attribute of the  device and sensor annunciation status object , then the phd agent transmits the object using a  remote operation invoke  confirmed event report  method . through this mechanism , the operational errors that occur in the pulse oximeter are reported to the personal monitoring server . the phd agent converts the stored pulse oximetry data and the detected errors into an 11073 message and transmits the message to the phd manager via bluetooth . although zigbee might be more suitable for a single signal transmission in terms of transmission range and network latency [ 11 , 12 ] , we plan to use the pulse oximeter to a remote management system . in the system , the pulse oximeter will be managed by a management server remotely . to achieve this , moreover , smartphones that support zigbee have not been released on the market thus far . the phd manager was implemented on an lg lu2300 smartphone ( now called an optimus q ) that is based on android 2.2 . in addition , sqlite , which is an embedded sql database engine , is used for storing pulse oximetry data . it also manages two components of the system configuration of the pulse oximeter : thresholds for spo2 and pulse rate and measurement targets . table 2 lists the manageable system configurations of the pulse oximeter . for example , if the phd manager transmits a  remote operation invoke  set  method with a specific value and targets the attribute  mdc_attr_limit_curr - min_spo2 ,  this reflects an attempt by the medical staff to change the lower threshold for spo2 to a desired value . the system configurations can be extended according to the management scenarios or target phds using the configuration phase described in figure 1 . figure 7 shows the screen of the phd agent for 11073 messages exchanged between the phd agent and the phd manager during a session . in figure 7 , the phd agent sends 11073 request messages ( represented as send - packagenum(1 , 3 , 5 )  ) and the phd manager sends response messages ( represented as  receive - packagenum(2 , 4 , 6 )  ) . the figure shows that the phd agent first sends the association request message and the phd manager responds with the  accepted  parameter . after that , the phd agent sends the event report message to transmit the measured spo2 and pulse rate , and the phd manager responds to the report . finally , the phd agent sends the association release request message and the phd manager responds to the request . based on this figure , the phd agent and phd manager exchange 11073 messages properly . . the patient can monitor pulse oximetry data through the gui . in figure 8(a ) , the pulse oximetry data transmitted from the phd agent is displayed on the screen of the smartphone . the phd manager provides a function to alert users to the detection of a low- or high - limit violation based on the predetermined threshold . a green background represents a normal level and a red background represents an abnormal level . based on figure 8(a ) , the spo2 of 97% is a normal level , but the pulse rate of 107  beats / min is an abnormal level . the phd manager also identifies patterns or changes in pulse oximetry data over a specific period of time , as shown in figure 8 . based on figure 8 , the phd manager receives pulse oximetry data from phd agent and displays these properly . hence , we evaluate the response times of the pulse oximeter for each phase , as shown in figure 9 .   as shown in this figure , the pulse oximeter requires an average of 6  s during the association phase , while requiring 251 and 119  ms during the operation and disassociation phases , respectively . such a large difference exists in the communication times because the communication time during the association phase includes the bluetooth connection time . however , it does not significantly affect the system performance because the association phase is experienced only once , and a bluetooth connection is established only when the physical connection between the pulse oximeter and the personal monitoring server is disconnected . the evaluation confirms that the proposed system is appropriate for monitoring and managing a pulse oximeter in real time . in this paper , we proposed an advanced pulse oximetry system for remote monitoring and management . the system consists of a networked pulse oximeter and a personal monitoring server . for the proposed system to support remote monitoring and management functions the phd agent within the pulse oximeter extracts the stored pulse oximetry data , detects operational errors , and transmits them to the personal monitoring server . the phd manager within the personal monitoring server analyzes , collects , and displays the pulse oximetry data sent by the pulse oximeter . it also manages system configurations of the pulse oximeter . the phd agent reports the detected operational errors using the  remote operation invoke  confirmed event report  method , and the phd manager manages system configurations of the pulse oximeter using  remote operation invoke  set  method . the determined errors and system configurations can be extended according to the management scenarios or target phds using the configuration phase . we also presented the results of the implementation and evaluation of the pulse oximetry system . the results confirmed that the proposed system is appropriate for monitoring and managing a pulse oximeter in real time . as future work , we plan to apply the product to other u - health services . we also plan to apply various protocols to connect between the personal monitoring server and health service providers .
pulse oximetry data such as saturation of peripheral oxygen ( spo2 ) and pulse rate are vital signals for early diagnosis of heart disease . 
 therefore , various pulse oximeters have been developed continuously . 
 however , some of the existing pulse oximeters are not equipped with communication capabilities , and consequently , the continuous monitoring of patient health is restricted . moreover , even though certain oximeters have been built as network models , they focus on exchanging only pulse oximetry data , and they do not provide sufficient device management functions . in this paper , we propose an advanced pulse oximetry system for remote monitoring and management . 
 the system consists of a networked pulse oximeter and a personal monitoring server . 
 the proposed pulse oximeter measures a patient 's pulse oximetry data and transmits the data to the personal monitoring server . 
 the personal monitoring server then analyzes the received data and displays the results to the patient . 
 furthermore , for device management purposes , operational errors that occur in the pulse oximeter are reported to the personal monitoring server , and the system configurations of the pulse oximeter , such as thresholds and measurement targets , are modified by the server . 
 we verify that the proposed pulse oximetry system operates efficiently and that it is appropriate for monitoring and managing a pulse oximeter in real time .