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- IoT Knowledge Base
- TCP (Transmission Control Protocol)
TCP (Transmission Control Protocol) in IoT
Quick Summary
In IoT, connectivity is the foundation that enables connected devices to exchange small but critical pieces of data, such as status updates, sensor readings, or commands. TCP (Transmission Control Protocol) provides a reliable and ordered communication channel for these exchanges. Although it wasn’t originally designed for low-power or lossy environments, TCP remains widely used in IoT for use cases where reliable delivery is more important than minimal latency.
How TCP Works in IoT
When used in IoT systems, TCP acts as a transport protocol that guarantees the delivery and correct order of data packets. Its operation begins with a handshake to establish a connection, followed by sequenced and acknowledged data transmission. This is particularly important in systems where dropped or corrupted packets could lead to device malfunctions or data loss.
Connection establishment (3-Way Handshake)
Even in constrained IoT environments, TCP uses a three-step handshake process to establish a connection between a device and a server or gateway:SYN: The device initiates the connection.
SYN-ACK: The server responds, confirming the request.
ACK: The device confirms receipt, and data exchange begins.
Reliable data transmission
Sensor data or commands are broken into packets and sent in sequence. TCP ensures the receiving party acknowledges each packet before continuing, guaranteeing delivery in the correct order.Error detection and correction
TCP checks the integrity of each packet using checksums. If errors are detected, the corrupted packets are automatically retransmitted.Flow and congestion control
Especially important in networks with variable performance (like LPWANs or mobile networks), TCP dynamically adjusts the transmission rate to prevent overwhelming devices with limited buffer capacity.Connection termination
Once data has been reliably delivered, TCP closes the connection in a controlled sequence, freeing up resources on constrained devices.
Benefits of TCP for IoT
For many IoT scenarios, especially those involving cloud communication, sensitive data, or remote firmware updates, TCP’s reliability features make it a strong choice. It ensures that critical updates or commands are not lost in transit, even over unstable networks.
Reliability | Perfect for IoT use cases where data accuracy matters, such as energy usage monitoring or remote diagnostics. |
Data integrity | TCP’s built-in error checking ensures sensor data reaches the cloud exactly as it was captured. |
Compatibility | TCP is the foundation of HTTP and MQTT, two commonly used IoT application protocols. |
Security support | Works well with TLS/SSL, enabling secure connections for sensitive data transmission. |
Persistent connections | Supports long-lived sessions ideal for continuous device-to-cloud synchronization |
Challenges of using TCP in IoT
Despite its strengths, TCP can be problematic for some IoT applications, particularly those with strict power, memory, or latency constraints. Its connection setup, acknowledgments, and retransmissions increase overhead, which can be costly for battery-powered devices or those using low-bandwidth networks.
High overhead | Connection management consumes more memory and power—difficult for microcontrollers or battery-powered nodes. |
Latency issues | TCP's retry and acknowledgment mechanism can introduce noticeable delays, especially in lossy or high-latency networks. |
Not optimal for broadcast/real-time use | In real-time sensing or one-to-many scenarios, TCP’s unicast and stateful nature can be inefficient. |
Connection reliability | Long-lasting TCP connections may time out or be interrupted in low-quality mobile or satellite links unless actively managed. |
TCP is not always the first choice in lightweight or time-critical IoT environments, but it remains essential where reliability, accuracy, and security are top priorities. It underpins key protocols like HTTP and MQTT, making it a foundational part of many IoT architectures, especially in cloud-connected, industrial, and smart infrastructure applications. Understanding its capabilities and trade-offs helps developers design more resilient and efficient IoT systems.
Looking to build reliable, secure IoT systems?
TCP is just one piece of the puzzle. Pelion helps you manage connectivity, security, and device integrity at scale.