Soft AP + STA Overview

With ever increasing wireless system and application demands, as well as the need for network flexibility, developers need solutions that provide them with the ability to accommodate these challenges. One powerful solution is Soft AP + STA Mode. Quite simply, this allows a Wi-Fi-enabled device to serve as an Access Point to some devices, while being an end device (STA) on another network. This capability provides developers with multiple options to address their technical and application needs. The key elements of this operation mode are as follows:

Soft AP Mode

See additional details in CEL’s Soft AP Mode blog post

  • This device uses its non-specialized and existing hardware to function as an Access Point through software.
  • It will broadcast its own wireless network.
  • Other devices like smartphones, laptops, or IoT devices connect to the device with Soft AP capability.
Diagram illustrating how a Smart IoT lightbulb uses SoftAP mode to create a Wi-Fi hotspot. A Smart Device (such as a smartphone) finds and joins the lightbulbs hotspot, enabling the user to control the lightbulb device via an app. The app interface on the smartphone screen displays an ON/OFF toggle for managing the device

STA/End-Device

  • This mode allows the given device to act as a client on a wireless network.
  • It uses the network’s internet connection for data exchange.
  • This is typical for IoT end devices like sensors, remote connection for monitoring and control of assets/equipment, laptops, and more.
Diagram illustrating a security camera operating in STA (Station) mode as a client on a network. The camera connects to a Wi-Fi router, which links to cloud storage for saving recorded footage. A mobile device accesses the live feed remotely for monitoring purposes

Soft AP + STA

  • The Wi-Fi-enabled device will combine the functions of Soft AP and STA mode, allowing it to play two roles simultaneously:
    • Role 1: It can act as an STA device on one network and perform various application functions like monitoring industrial equipment or providing vital sensor data to a remote server.
    • Role 2: It allows other STAs to connect to it, giving them remote network capability that they cannot establish directly on their own.
  • Dual roles and functionality provide network flexibility and address many application use cases.

Use Cases

This dual capability can address some common use cases:

  • Network Provisioning: With the use of a smart device or tablet, a user can connect to a Soft AP + STA device while it’s in Soft AP mode and establish its permanent connection to the local wireless network.
  • Bridging Networks: A device could become a bridge between two different Wi-Fi networks, enabling devices on different networks to communicate with one another.
  • STA Device: When not acting as a bridge, service access point, or used for provisioning, it can function like any other end-device (input, output, monitoring) in a given network.
  • Secure Service Access: If the device is in Soft AP mode, it could temporarily allow service people or technicians to access the system or device without needing to gain access to the local network.
  • Remote & Temporary/Permanent Access: Providing access to/from other STAs in a network that don’t have a direct link to the local network infrastructure.

A network diagram showing how a Soft AP + STA device bridges two networks. The STA mode connects to the main network, while the Soft AP mode creates a hotspot for IoT devices. These IoT devices connect to the Soft AP network and gain access to the main network through the STA connection. The diagram includes a modem, router, wireless bridge, and pre-configured sensors.

Key Benefits

Flexibility is probably the #1 benefit to Soft AP + STA. As aforementioned, developers are faced with designing and implementing solutions that need to address ever changing applications and demanding use cases. This affords them the ability to tailor a system that best meets their needs. Additionally, in many cases, having one device to support multiple roles and functions can simplify the given end solution. Having a multi-functional device in the network can also help reduce system and installation costs. Finally, with multi-functional ability, there is flexibility to change, update, or expand the system in the future.

Considerations and Challenges

Although there are numerous benefits to Soft AP + STA, developers must consider and accommodate some key challenges. First, running both modes simultaneously may require additional processing horsepower, which impacts the host design, complexity, cost, Etc. Additionally, resource management may become more critical. Next, power consumption will increase, so energy restricted applications and devices will need special consideration in terms of their power source, resource utilization, and application development. Since one device will be responsible for running its own application and managing a local network, system performance will degrade; to what extent depends heavily on the HOST processing capability, its ability to manage resources, and supporting the application needs of all devices in the system. Due to the potentially high demands of managing a network and being a STA device, the managed network is usually smaller in size compared to a system using a dedicated AP that has specialized hardware and software.

Let CEL Help

Soft AP + STA mode is a powerful feature that allows devices to be more versatile, enabling them to function both as a local Wi-Fi hotspot and as a client on another network. This dual functionality is critical for today’s systems and applications.

The majority of CEL’s solutions offer Soft AP +STA functionality. Please contact CEL for details and how we can assist you in your system and application development.