Chapter 8: WIA-MEDICAL-IOT Standard

8.1 Standard Overview

The WIA-MEDICAL-IOT standard provides a comprehensive framework for implementing secure, interoperable Internet of Medical Things systems. Built on the WIA 4-phase architecture (Data, API, Protocol, Integration), this standard enables seamless connectivity between medical devices, remote monitoring platforms, clinical systems, and analytics applications.

Guided by the principle of 弘益人間 (Hongik Ingan) - "Benefit All Humanity" - this standard aims to make connected health technologies accessible globally, enabling continuous care and early intervention regardless of geographic or economic barriers.

8.2 WIA 4-Phase Architecture

The WIA-MEDICAL-IOT standard implements the WIA 4-phase architecture pattern:

Phase	Name	Purpose	Components
Phase 1	Data Layer	Information modeling	Device, Observation, Patient models
Phase 2	API Layer	Programmatic access	FHIR APIs, device management, alerts
Phase 3	Protocol Layer	Device communication	BLE PHD, MQTT, IEEE 11073
Phase 4	Integration Layer	External connectivity	EHR, RPM platforms, analytics

8.3 Phase 1: Data Layer Specification

The Data Layer defines core information models aligned with FHIR and IEEE 11073 standards:

Core Data Models

Device Model

{
  "resourceType": "Device",
  "id": "string (UUID)",
  "identifier": [{
    "system": "urn:ietf:rfc:3986",
    "value": "UDI (Unique Device Identifier)"
  }],
  "status": "active | inactive | entered-in-error",
  "manufacturer": "string",
  "deviceName": [{
    "name": "string",
    "type": "udi-label-name | user-friendly-name | patient-reported-name"
  }],
  "modelNumber": "string",
  "serialNumber": "string",
  "type": {
    "coding": [{
      "system": "urn:iso:std:iso:11073:10101",
      "code": "device type code"
    }]
  },
  "patient": { "reference": "Patient/123" },
  "owner": { "reference": "Organization/456" }
}

Observation Model

{
  "resourceType": "Observation",
  "id": "string (UUID)",
  "status": "final | preliminary",
  "category": [{
    "coding": [{
      "system": "http://terminology.hl7.org/CodeSystem/observation-category",
      "code": "vital-signs"
    }]
  }],
  "code": {
    "coding": [{
      "system": "http://loinc.org",
      "code": "LOINC code",
      "display": "Measurement type"
    }]
  },
  "subject": { "reference": "Patient/123" },
  "effectiveDateTime": "2025-01-15T10:30:00Z",
  "device": { "reference": "Device/456" },
  "valueQuantity": {
    "value": 120,
    "unit": "mmHg",
    "system": "http://unitsofmeasure.org",
    "code": "mm[Hg]"
  }
}

Alert Model

{
  "alertId": "string (UUID)",
  "patientId": "string",
  "deviceId": "string",
  "alertType": "threshold | trend | missing-data | device-issue",
  "severity": "critical | high | medium | low",
  "condition": {
    "parameter": "string (e.g., 'systolic_bp')",
    "operator": "gt | lt | eq | trend_up | trend_down",
    "value": "number",
    "duration": "ISO 8601 duration"
  },
  "triggerObservation": { "reference": "Observation/789" },
  "status": "active | acknowledged | resolved",
  "timestamp": "datetime",
  "assignedTo": { "reference": "Practitioner/321" }
}

8.4 Phase 2: API Layer Specification

The API Layer provides RESTful endpoints for device management and data access:

API Endpoints Overview

Category	Endpoint	Method	Description
Devices	/api/v1/devices	GET	List devices (filtered)
	/api/v1/devices/{id}	GET	Get device details
	/api/v1/devices/{id}/assign	POST	Assign device to patient
Observations	/fhir/Observation	GET	Query observations
	/fhir/Observation	POST	Submit observation
	/api/v1/observations/aggregate	GET	Get aggregated data
Alerts	/api/v1/alerts	GET	Query active alerts
	/api/v1/alerts/{id}/acknowledge	POST	Acknowledge alert
	/api/v1/alert-rules	POST	Configure alert rules
Programs	/api/v1/programs	GET	List RPM programs
	/api/v1/programs/{id}/enroll	POST	Enroll patient

8.5 Phase 3: Protocol Layer Specification

The Protocol Layer defines communication standards for device connectivity:

Supported Protocols

Protocol	Use Case	Standard
Bluetooth PHD	Personal health devices	IEEE 11073-20601, GATT profiles
MQTT	IoT messaging	MQTT 3.1.1/5.0 over TLS
HTTP/REST	Gateway to cloud	HTTPS, FHIR REST
WebSocket	Real-time streaming	WSS for live data
CoAP	Constrained devices	CoAP over DTLS

MQTT Topic Structure

// Device telemetry
wia/iomt/{org_id}/devices/{device_id}/telemetry

// Device status
wia/iomt/{org_id}/devices/{device_id}/status

// Alerts
wia/iomt/{org_id}/patients/{patient_id}/alerts

// Commands to device
wia/iomt/{org_id}/devices/{device_id}/commands

// Example message payload
{
  "device_id": "bp-monitor-123",
  "timestamp": "2025-01-15T10:30:00Z",
  "measurements": [
    { "type": "systolic_bp", "value": 120, "unit": "mmHg" },
    { "type": "diastolic_bp", "value": 80, "unit": "mmHg" },
    { "type": "pulse", "value": 72, "unit": "bpm" }
  ]
}

8.6 Phase 4: Integration Layer Specification

The Integration Layer connects IoMT systems with healthcare ecosystem:

Integration Patterns

System	Integration Method	Data Exchanged
EHR	FHIR API, SMART on FHIR	Observations, devices, care plans
RPM Platform	REST API, webhooks	Device data, alerts, programs
Analytics	Event streaming, batch export	Time-series data, outcomes
Patient App	Mobile SDK, push notifications	Readings, education, reminders
Billing	ADT events, charge capture	RPM codes, transmission days

8.7 Security Framework

Security requirements across all phases:

Layer	Requirements	Implementation
Device	Secure boot, authentication	Certificates, secure elements
Transport	Encryption in transit	TLS 1.3, DTLS, BLE encryption
API	Authentication, authorization	OAuth 2.0, JWT, RBAC
Data	Encryption at rest	AES-256, key management

8.8 Compliance Mapping

Framework	Standard Elements	Coverage
HL7 FHIR	Device, Observation, Patient	R4 aligned
IEEE 11073	PHD profiles, nomenclature	Full support
HIPAA	Privacy, security	Encryption, access control
FDA	SaMD, cybersecurity	Audit, traceability