# Architecture Overview

## Overview

The WiFi-DensePose system is a distributed, microservices-based architecture that transforms WiFi Channel State Information (CSI) into real-time human pose estimation. This document provides a comprehensive overview of the system architecture, component interactions, and design principles.

## Table of Contents

1. [System Architecture](#system-architecture)
2. [Core Components](#core-components)
3. [Data Flow](#data-flow)
4. [Processing Pipeline](#processing-pipeline)
5. [API Architecture](#api-architecture)
6. [Storage Architecture](#storage-architecture)
7. [Security Architecture](#security-architecture)
8. [Deployment Architecture](#deployment-architecture)
9. [Scalability and Performance](#scalability-and-performance)
10. [Design Principles](#design-principles)

## System Architecture

### High-Level Architecture

```
┌─────────────────────────────────────────────────────────────────┐
│                        WiFi-DensePose System                    │
├─────────────────────────────────────────────────────────────────┤
│  ┌─────────────────┐  ┌─────────────────┐  ┌─────────────────┐  │
│  │   Client Apps   │  │   Web Dashboard │  │  Mobile Apps    │  │
│  └─────────────────┘  └─────────────────┘  └─────────────────┘  │
├─────────────────────────────────────────────────────────────────┤
│                        API Gateway                              │
├─────────────────────────────────────────────────────────────────┤
│  ┌─────────────────┐  ┌─────────────────┐  ┌─────────────────┐  │
│  │   REST API      │  │  WebSocket API  │  │   MQTT Broker   │  │
│  └─────────────────┘  └─────────────────┘  └─────────────────┘  │
├─────────────────────────────────────────────────────────────────┤
│                      Processing Layer                           │
│  ┌─────────────────┐  ┌─────────────────┐  ┌─────────────────┐  │
│  │ Pose Estimation │  │    Tracking     │  │   Analytics     │  │
│  │    Service      │  │    Service      │  │    Service      │  │
│  └─────────────────┘  └─────────────────┘  └─────────────────┘  │
├─────────────────────────────────────────────────────────────────┤
│                       Data Layer                                │
│  ┌─────────────────┐  ┌─────────────────┐  ┌─────────────────┐  │
│  │ CSI Processor   │  │  Data Pipeline  │  │  Model Manager  │  │
│  └─────────────────┘  └─────────────────┘  └─────────────────┘  │
├─────────────────────────────────────────────────────────────────┤
│                     Hardware Layer                              │
│  ┌─────────────────┐  ┌─────────────────┐  ┌─────────────────┐  │
│  │  WiFi Routers   │  │ Processing Unit │  │   GPU Cluster   │  │
│  │   (CSI Data)    │  │   (CPU/Memory)  │  │  (Neural Net)   │  │
│  └─────────────────┘  └─────────────────┘  └─────────────────┘  │
└─────────────────────────────────────────────────────────────────┘
```

### Component Interaction Diagram

```
┌─────────────┐    CSI Data    ┌─────────────┐    Features    ┌─────────────┐
│   Router    │ ──────────────▶│ CSI         │ ──────────────▶│ Feature     │
│   Network   │                │ Processor   │                │ Extractor   │
└─────────────┘                └─────────────┘                └─────────────┘
                                       │                              │
                                       ▼                              ▼
┌─────────────┐    Poses       ┌─────────────┐    Inference   ┌─────────────┐
│   Client    │ ◀──────────────│ Pose        │ ◀──────────────│ Neural      │
│ Applications│                │ Tracker     │                │ Network     │
└─────────────┘                └─────────────┘                └─────────────┘
       │                               │                              │
       ▼                               ▼                              ▼
┌─────────────┐    Events      ┌─────────────┐    Models      ┌─────────────┐
│ Alert       │ ◀──────────────│ Analytics   │ ◀──────────────│ Model       │
│ System      │                │ Engine      │                │ Manager     │
└─────────────┘                └─────────────┘                └─────────────┘
```

## Core Components

### 1. CSI Data Processor

**Purpose**: Receives and processes raw Channel State Information from WiFi routers.

**Key Features**:
- Real-time CSI data ingestion from multiple routers
- Signal preprocessing and noise reduction
- Phase sanitization and amplitude normalization
- Multi-antenna data fusion

**Implementation**: [`src/hardware/csi_processor.py`](../../src/hardware/csi_processor.py)

```python
class CSIProcessor:
    """Processes raw CSI data from WiFi routers."""
    
    def __init__(self, config: CSIConfig):
        self.routers = self._initialize_routers(config.routers)
        self.buffer = CircularBuffer(config.buffer_size)
        self.preprocessor = CSIPreprocessor()
    
    async def process_stream(self) -> AsyncGenerator[CSIData, None]:
        """Process continuous CSI data stream."""
        async for raw_data in self._receive_csi_data():
            processed_data = self.preprocessor.process(raw_data)
            yield processed_data
```

### 2. Neural Network Service

**Purpose**: Performs pose estimation using deep learning models.

**Key Features**:
- DensePose model inference
- Batch processing optimization
- GPU acceleration support
- Model versioning and hot-swapping

**Implementation**: [`src/neural_network/inference.py`](../../src/neural_network/inference.py)

```python
class PoseEstimationService:
    """Neural network service for pose estimation."""
    
    def __init__(self, model_config: ModelConfig):
        self.model = self._load_model(model_config.model_path)
        self.device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
        self.batch_processor = BatchProcessor(model_config.batch_size)
    
    async def estimate_poses(self, csi_features: CSIFeatures) -> List[PoseEstimation]:
        """Estimate human poses from CSI features."""
        with torch.no_grad():
            predictions = self.model(csi_features.to(self.device))
            return self._postprocess_predictions(predictions)
```

### 3. Tracking Service

**Purpose**: Maintains temporal consistency and person identity across frames.

**Key Features**:
- Multi-object tracking with Kalman filters
- Person re-identification
- Track lifecycle management
- Trajectory smoothing

**Implementation**: [`src/tracking/tracker.py`](../../src/tracking/tracker.py)

```python
class PersonTracker:
    """Tracks multiple persons across time."""
    
    def __init__(self, tracking_config: TrackingConfig):
        self.tracks = {}
        self.track_id_counter = 0
        self.kalman_filter = KalmanFilter()
        self.reid_model = ReIDModel()
    
    def update(self, detections: List[PoseDetection]) -> List[TrackedPose]:
        """Update tracks with new detections."""
        matched_tracks, unmatched_detections = self._associate_detections(detections)
        self._update_matched_tracks(matched_tracks)
        self._create_new_tracks(unmatched_detections)
        return self._get_active_tracks()
```

### 4. API Gateway

**Purpose**: Provides unified access to system functionality through REST and WebSocket APIs.

**Key Features**:
- Authentication and authorization
- Rate limiting and throttling
- Request routing and load balancing
- API versioning

**Implementation**: [`src/api/main.py`](../../src/api/main.py)

```python
from fastapi import FastAPI, Depends
from fastapi.middleware.cors import CORSMiddleware

app = FastAPI(
    title="WiFi-DensePose API",
    version="1.0.0",
    description="Privacy-preserving human pose estimation using WiFi signals"
)

# Middleware
app.add_middleware(CORSMiddleware, **get_cors_config())
app.add_middleware(RateLimitMiddleware)
app.add_middleware(AuthenticationMiddleware)

# Routers
app.include_router(pose_router, prefix="/api/v1/pose")
app.include_router(system_router, prefix="/api/v1/system")
app.include_router(analytics_router, prefix="/api/v1/analytics")
```

### 5. Analytics Engine

**Purpose**: Processes pose data to generate insights and trigger alerts.

**Key Features**:
- Real-time event detection (falls, intrusions)
- Statistical analysis and reporting
- Domain-specific analytics (healthcare, retail, security)
- Machine learning-based pattern recognition

**Implementation**: [`src/analytics/engine.py`](../../src/analytics/engine.py)

```python
class AnalyticsEngine:
    """Processes pose data for insights and alerts."""
    
    def __init__(self, domain_config: DomainConfig):
        self.domain = domain_config.domain
        self.event_detectors = self._load_event_detectors(domain_config)
        self.alert_manager = AlertManager(domain_config.alerts)
    
    async def process_poses(self, poses: List[TrackedPose]) -> AnalyticsResult:
        """Process poses and generate analytics."""
        events = []
        for detector in self.event_detectors:
            detected_events = await detector.detect(poses)
            events.extend(detected_events)
        
        await self.alert_manager.process_events(events)
        return AnalyticsResult(events=events, metrics=self._calculate_metrics(poses))
```

## Data Flow

### Real-Time Processing Pipeline

```
1. CSI Data Acquisition
   ┌─────────────┐
   │   Router 1  │ ──┐
   └─────────────┘   │
   ┌─────────────┐   │    ┌─────────────┐
   │   Router 2  │ ──┼───▶│ CSI Buffer  │
   └─────────────┘   │    └─────────────┘
   ┌─────────────┐   │           │
   │   Router N  │ ──┘           ▼
   └─────────────┘       ┌─────────────┐
                         │ Preprocessor│
                         └─────────────┘
                                │
2. Feature Extraction           ▼
   ┌─────────────┐       ┌─────────────┐
   │   Phase     │ ◀─────│ Feature     │
   │ Sanitizer   │       │ Extractor   │
   └─────────────┘       └─────────────┘
          │                     │
          ▼                     ▼
   ┌─────────────┐       ┌─────────────┐
   │ Amplitude   │       │ Frequency   │
   │ Processor   │       │ Analyzer    │
   └─────────────┘       └─────────────┘
          │                     │
          └──────┬──────────────┘
                 ▼
3. Neural Network Inference
   ┌─────────────┐
   │ DensePose   │
   │   Model     │
   └─────────────┘
          │
          ▼
   ┌─────────────┐
   │ Pose        │
   │ Decoder     │
   └─────────────┘
          │
4. Tracking and Analytics      ▼
   ┌─────────────┐       ┌─────────────┐
   │ Person      │ ◀─────│ Raw Pose    │
   │ Tracker     │       │ Detections  │
   └─────────────┘       └─────────────┘
          │
          ▼
   ┌─────────────┐
   │ Analytics   │
   │ Engine      │
   └─────────────┘
          │
5. Output and Storage          ▼
   ┌─────────────┐       ┌─────────────┐
   │ WebSocket   │ ◀─────│ Tracked     │
   │ Streams     │       │ Poses       │
   └─────────────┘       └─────────────┘
          │                     │
          ▼                     ▼
   ┌─────────────┐       ┌─────────────┐
   │ Client      │       │ Database    │
   │ Applications│       │ Storage     │
   └─────────────┘       └─────────────┘
```

### Data Models

#### CSI Data Structure

```python
@dataclass
class CSIData:
    """Channel State Information data structure."""
    timestamp: datetime
    router_id: str
    antenna_pairs: List[AntennaPair]
    subcarriers: List[SubcarrierData]
    metadata: CSIMetadata

@dataclass
class SubcarrierData:
    """Individual subcarrier information."""
    frequency: float
    amplitude: complex
    phase: float
    snr: float
```

#### Pose Data Structure

```python
@dataclass
class PoseEstimation:
    """Human pose estimation result."""
    person_id: Optional[int]
    confidence: float
    bounding_box: BoundingBox
    keypoints: List[Keypoint]
    dense_pose: Optional[DensePoseResult]
    timestamp: datetime

@dataclass
class TrackedPose:
    """Tracked pose with temporal information."""
    track_id: int
    pose: PoseEstimation
    velocity: Vector2D
    track_age: int
    track_confidence: float
```

## Processing Pipeline

### 1. CSI Preprocessing

```python
class CSIPreprocessor:
    """Preprocesses raw CSI data for neural network input."""
    
    def __init__(self, config: PreprocessingConfig):
        self.phase_sanitizer = PhaseSanitizer()
        self.amplitude_normalizer = AmplitudeNormalizer()
        self.noise_filter = NoiseFilter(config.filter_params)
    
    def process(self, raw_csi: RawCSIData) -> ProcessedCSIData:
        """Process raw CSI data."""
        # Phase unwrapping and sanitization
        sanitized_phase = self.phase_sanitizer.sanitize(raw_csi.phase)
        
        # Amplitude normalization
        normalized_amplitude = self.amplitude_normalizer.normalize(raw_csi.amplitude)
        
        # Noise filtering
        filtered_data = self.noise_filter.filter(sanitized_phase, normalized_amplitude)
        
        return ProcessedCSIData(
            phase=filtered_data.phase,
            amplitude=filtered_data.amplitude,
            timestamp=raw_csi.timestamp,
            metadata=raw_csi.metadata
        )
```

### 2. Feature Extraction

```python
class FeatureExtractor:
    """Extracts features from processed CSI data."""
    
    def __init__(self, config: FeatureConfig):
        self.window_size = config.window_size
        self.feature_types = config.feature_types
        self.pca_reducer = PCAReducer(config.pca_components)
    
    def extract_features(self, csi_data: ProcessedCSIData) -> CSIFeatures:
        """Extract features for neural network input."""
        features = {}
        
        if 'amplitude' in self.feature_types:
            features['amplitude'] = self._extract_amplitude_features(csi_data)
        
        if 'phase' in self.feature_types:
            features['phase'] = self._extract_phase_features(csi_data)
        
        if 'doppler' in self.feature_types:
            features['doppler'] = self._extract_doppler_features(csi_data)
        
        # Dimensionality reduction
        reduced_features = self.pca_reducer.transform(features)
        
        return CSIFeatures(
            features=reduced_features,
            timestamp=csi_data.timestamp,
            feature_types=self.feature_types
        )
```

### 3. Neural Network Architecture

```python
class DensePoseNet(nn.Module):
    """DensePose neural network for WiFi-based pose estimation."""
    
    def __init__(self, config: ModelConfig):
        super().__init__()
        self.backbone = self._build_backbone(config.backbone)
        self.feature_pyramid = FeaturePyramidNetwork(config.fpn)
        self.pose_head = PoseEstimationHead(config.pose_head)
        self.dense_pose_head = DensePoseHead(config.dense_pose_head)
    
    def forward(self, csi_features: torch.Tensor) -> Dict[str, torch.Tensor]:
        """Forward pass through the network."""
        # Feature extraction
        backbone_features = self.backbone(csi_features)
        pyramid_features = self.feature_pyramid(backbone_features)
        
        # Pose estimation
        pose_predictions = self.pose_head(pyramid_features)
        dense_pose_predictions = self.dense_pose_head(pyramid_features)
        
        return {
            'poses': pose_predictions,
            'dense_poses': dense_pose_predictions
        }
```

## API Architecture

### REST API Design

The REST API follows RESTful principles with clear resource hierarchies:

```
/api/v1/
├── auth/
│   ├── token          # POST: Get authentication token
│   └── verify         # POST: Verify token validity
├── system/
│   ├── status         # GET: System health status
│   ├── start          # POST: Start pose estimation
│   ├── stop           # POST: Stop pose estimation
│   └── diagnostics    # GET: System diagnostics
├── pose/
│   ├── latest         # GET: Latest pose data
│   ├── history        # GET: Historical pose data
│   └── query          # POST: Complex pose queries
├── config/
│   └── [resource]     # GET/PUT: Configuration management
└── analytics/
    ├── healthcare     # GET: Healthcare analytics
    ├── retail         # GET: Retail analytics
    └── security       # GET: Security analytics
```

### WebSocket API Design

```python
class WebSocketManager:
    """Manages WebSocket connections and subscriptions."""
    
    def __init__(self):
        self.connections: Dict[str, WebSocket] = {}
        self.subscriptions: Dict[str, Set[str]] = {}
    
    async def handle_connection(self, websocket: WebSocket, client_id: str):
        """Handle new WebSocket connection."""
        await websocket.accept()
        self.connections[client_id] = websocket
        
        try:
            async for message in websocket.iter_text():
                await self._handle_message(client_id, json.loads(message))
        except WebSocketDisconnect:
            self._cleanup_connection(client_id)
    
    async def broadcast_pose_update(self, pose_data: TrackedPose):
        """Broadcast pose updates to subscribed clients."""
        message = {
            'type': 'pose_update',
            'data': pose_data.to_dict(),
            'timestamp': datetime.utcnow().isoformat()
        }
        
        for client_id in self.subscriptions.get('pose_updates', set()):
            if client_id in self.connections:
                await self.connections[client_id].send_text(json.dumps(message))
```

## Storage Architecture

### Database Design

#### Time-Series Data (PostgreSQL + TimescaleDB)

```sql
-- Pose data table with time-series optimization
CREATE TABLE pose_data (
    id BIGSERIAL PRIMARY KEY,
    timestamp TIMESTAMPTZ NOT NULL,
    frame_id BIGINT NOT NULL,
    person_id INTEGER,
    track_id INTEGER,
    confidence REAL NOT NULL,
    bounding_box JSONB NOT NULL,
    keypoints JSONB NOT NULL,
    dense_pose JSONB,
    metadata JSONB,
    environment_id VARCHAR(50) NOT NULL
);

-- Convert to hypertable for time-series optimization
SELECT create_hypertable('pose_data', 'timestamp');

-- Create indexes for common queries
CREATE INDEX idx_pose_data_timestamp ON pose_data (timestamp DESC);
CREATE INDEX idx_pose_data_person_id ON pose_data (person_id, timestamp DESC);
CREATE INDEX idx_pose_data_environment ON pose_data (environment_id, timestamp DESC);
```

#### Configuration Storage (PostgreSQL)

```sql
-- System configuration
CREATE TABLE system_config (
    id SERIAL PRIMARY KEY,
    domain VARCHAR(50) NOT NULL,
    environment_id VARCHAR(50) NOT NULL,
    config_data JSONB NOT NULL,
    created_at TIMESTAMPTZ DEFAULT NOW(),
    updated_at TIMESTAMPTZ DEFAULT NOW(),
    UNIQUE(domain, environment_id)
);

-- Model metadata
CREATE TABLE model_metadata (
    id SERIAL PRIMARY KEY,
    model_name VARCHAR(100) NOT NULL,
    model_version VARCHAR(20) NOT NULL,
    model_path TEXT NOT NULL,
    config JSONB NOT NULL,
    performance_metrics JSONB,
    created_at TIMESTAMPTZ DEFAULT NOW(),
    UNIQUE(model_name, model_version)
);
```

### Caching Strategy (Redis)

```python
class CacheManager:
    """Manages Redis caching for frequently accessed data."""
    
    def __init__(self, redis_client: Redis):
        self.redis = redis_client
        self.default_ttl = 300  # 5 minutes
    
    async def cache_pose_data(self, pose_data: TrackedPose, ttl: int = None):
        """Cache pose data with automatic expiration."""
        key = f"pose:latest:{pose_data.track_id}"
        value = json.dumps(pose_data.to_dict(), default=str)
        await self.redis.setex(key, ttl or self.default_ttl, value)
    
    async def get_cached_poses(self, track_ids: List[int]) -> List[TrackedPose]:
        """Retrieve cached pose data for multiple tracks."""
        keys = [f"pose:latest:{track_id}" for track_id in track_ids]
        cached_data = await self.redis.mget(keys)
        
        poses = []
        for data in cached_data:
            if data:
                pose_dict = json.loads(data)
                poses.append(TrackedPose.from_dict(pose_dict))
        
        return poses
```

## Security Architecture

### Authentication and Authorization

```python
class SecurityManager:
    """Handles authentication and authorization."""
    
    def __init__(self, config: SecurityConfig):
        self.jwt_secret = config.jwt_secret
        self.jwt_algorithm = config.jwt_algorithm
        self.token_expiry = config.token_expiry
    
    def create_access_token(self, user_data: dict) -> str:
        """Create JWT access token."""
        payload = {
            'sub': user_data['username'],
            'exp': datetime.utcnow() + timedelta(hours=self.token_expiry),
            'iat': datetime.utcnow(),
            'permissions': user_data.get('permissions', [])
        }
        return jwt.encode(payload, self.jwt_secret, algorithm=self.jwt_algorithm)
    
    def verify_token(self, token: str) -> dict:
        """Verify and decode JWT token."""
        try:
            payload = jwt.decode(token, self.jwt_secret, algorithms=[self.jwt_algorithm])
            return payload
        except jwt.ExpiredSignatureError:
            raise HTTPException(status_code=401, detail="Token expired")
        except jwt.InvalidTokenError:
            raise HTTPException(status_code=401, detail="Invalid token")
```

### Data Privacy

```python
class PrivacyManager:
    """Manages data privacy and anonymization."""
    
    def __init__(self, config: PrivacyConfig):
        self.anonymization_enabled = config.anonymization_enabled
        self.data_retention_days = config.data_retention_days
        self.encryption_key = config.encryption_key
    
    def anonymize_pose_data(self, pose_data: TrackedPose) -> TrackedPose:
        """Anonymize pose data for privacy protection."""
        if not self.anonymization_enabled:
            return pose_data
        
        # Remove or hash identifying information
        anonymized_data = pose_data.copy()
        anonymized_data.track_id = self._hash_track_id(pose_data.track_id)
        
        # Apply differential privacy to keypoints
        anonymized_data.pose.keypoints = self._add_noise_to_keypoints(
            pose_data.pose.keypoints
        )
        
        return anonymized_data
```

## Deployment Architecture

### Container Architecture

```yaml
# docker-compose.yml
version: '3.8'
services:
  wifi-densepose-api:
    build: .
    ports:
      - "8000:8000"
    environment:
      - DATABASE_URL=postgresql://user:pass@postgres:5432/wifi_densepose
      - REDIS_URL=redis://redis:6379/0
    depends_on:
      - postgres
      - redis
      - neural-network
    volumes:
      - ./data:/app/data
      - ./models:/app/models
  
  neural-network:
    build: ./neural_network
    runtime: nvidia
    environment:
      - CUDA_VISIBLE_DEVICES=0
    volumes:
      - ./models:/app/models
  
  postgres:
    image: timescale/timescaledb:latest-pg14
    environment:
      - POSTGRES_DB=wifi_densepose
      - POSTGRES_USER=user
      - POSTGRES_PASSWORD=password
    volumes:
      - postgres_data:/var/lib/postgresql/data
  
  redis:
    image: redis:7-alpine
    volumes:
      - redis_data:/data

volumes:
  postgres_data:
  redis_data:
```

### Kubernetes Deployment

```yaml
# k8s/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: wifi-densepose-api
spec:
  replicas: 3
  selector:
    matchLabels:
      app: wifi-densepose-api
  template:
    metadata:
      labels:
        app: wifi-densepose-api
    spec:
      containers:
      - name: api
        image: wifi-densepose:latest
        ports:
        - containerPort: 8000
        env:
        - name: DATABASE_URL
          valueFrom:
            secretKeyRef:
              name: database-secret
              key: url
        resources:
          requests:
            memory: "2Gi"
            cpu: "1000m"
          limits:
            memory: "4Gi"
            cpu: "2000m"
```

## Scalability and Performance

### Horizontal Scaling

```python
class LoadBalancer:
    """Distributes processing load across multiple instances."""
    
    def __init__(self, config: LoadBalancerConfig):
        self.processing_nodes = config.processing_nodes
        self.load_balancing_strategy = config.strategy
        self.health_checker = HealthChecker()
    
    async def distribute_csi_data(self, csi_data: CSIData) -> str:
        """Distribute CSI data to available processing nodes."""
        available_nodes = await self.health_checker.get_healthy_nodes()
        
        if self.load_balancing_strategy == 'round_robin':
            node = self._round_robin_selection(available_nodes)
        elif self.load_balancing_strategy == 'least_loaded':
            node = await self._least_loaded_selection(available_nodes)
        else:
            node = random.choice(available_nodes)
        
        await self._send_to_node(node, csi_data)
        return node.id
```

### Performance Optimization

```python
class PerformanceOptimizer:
    """Optimizes system performance based on runtime metrics."""
    
    def __init__(self, config: OptimizationConfig):
        self.metrics_collector = MetricsCollector()
        self.auto_scaling_enabled = config.auto_scaling_enabled
        self.optimization_interval = config.optimization_interval
    
    async def optimize_processing_pipeline(self):
        """Optimize processing pipeline based on current metrics."""
        metrics = await self.metrics_collector.get_current_metrics()
        
        # Adjust batch size based on GPU utilization
        if metrics.gpu_utilization < 0.7:
            await self._increase_batch_size()
        elif metrics.gpu_utilization > 0.9:
            await self._decrease_batch_size()
        
        # Scale processing nodes based on queue length
        if metrics.processing_queue_length > 100:
            await self._scale_up_processing_nodes()
        elif metrics.processing_queue_length < 10:
            await self._scale_down_processing_nodes()
```

## Design Principles

### 1. Modularity and Separation of Concerns

- Each component has a single, well-defined responsibility
- Clear interfaces between components
- Pluggable architecture for easy component replacement

### 2. Scalability

- Horizontal scaling support through microservices
- Stateless service design where possible
- Efficient resource utilization and load balancing

### 3. Reliability and Fault Tolerance

- Graceful degradation under failure conditions
- Circuit breaker patterns for external dependencies
- Comprehensive error handling and recovery mechanisms

### 4. Performance

- Optimized data structures and algorithms
- Efficient memory management and garbage collection
- GPU acceleration for compute-intensive operations

### 5. Security and Privacy

- Defense in depth security model
- Data encryption at rest and in transit
- Privacy-preserving data processing techniques

### 6. Observability

- Comprehensive logging and monitoring
- Distributed tracing for request flow analysis
- Performance metrics and alerting

### 7. Maintainability

- Clean code principles and consistent coding standards
- Comprehensive documentation and API specifications
- Automated testing and continuous integration

---

This architecture overview provides the foundation for understanding the WiFi-DensePose system. For implementation details, see:

- [API Architecture](../api/rest-endpoints.md)
- [Neural Network Architecture](../../plans/phase2-architecture/neural-network-architecture.md)
- [Hardware Integration](../../plans/phase2-architecture/hardware-integration.md)
- [Deployment Guide](deployment-guide.md)