Wi-Fi Direct — Enabling Direct Connectivity between Wi-Fi Devices

Wi-Fi has become a first choice for short range communication in many applications, due to the cost effective deployment of Wi-Fi networks, its large scale implementation and availability of Wi-Fi devices e.g. smartphones, consumer electronics and industry sensors. In the current deployment of Wi-Fi, devices connect to a common Access Point (AP) to connect to other Wi-Fi devices.

In 2010, Wi-Fi Alliance introduced the Wi-Fi Direct technology, to directly connect Wi-Fi devicess to each other without connecting to an AP. Wi-Fi Direct, initially called Wi-Fi Peer-to-Peer (Wi-Fi P2P), is built upon the IEEE 802.11 infrastructure mode and offers direct, secure and rapid device to device communication.

Technical Overview:

Wi-Fi Direct enables Wi-Fi devices to communicate directly without incorporating an Access Point (AP). The functional entity of Wi-Fi Direct architecture is called a “P2P Group” that is functionally equivalent to a Basic Service Set (BSS) in legacy Wi-Fi network. A P2P Group consists of a P2P Group Owner (P2P GO) and zero or more P2P Clients. The P2P GO (sometimes referred to as “GO”) is also called a Soft-AP. The roles of P2P Devices (i.e. P2P GO and P2P Client) are usually negotiated before creating a P2P Group and remain fixed while the P2P Group is active. Prior to form a P2P Group, a P2P Device runs the Device Discovery procedure to detect the presence of other P2P Devices in its wireless range. Wi-Fi Direct also has an optional service discovery procedure to automatically discover network services using upper layer protocols such as Bonjour and Universal Plug and Play (UPnP).

Applications:

1. File Transfer: Transferring files using the Send service in Wi-Fi Direct is simple and efficient as compared to other short range (SR) communication options such as Bluetooth. Several applications are developed on Android OS that make use of Wi-Fi Direct to transfer files between mobiles at Wi-Fi rates. Wi-Fi Shoot, SuperBeam, WiFi Direct Share and SHAREit are examples of file transfer mobile applications available on the Android application store.
2. Resource Sharing: Wi-Fi Direct can be used to easily print files from smartphones, tablets or laptops directly without connecting to the network. Internet connection sharing was already possible in legacy Wi-Fi using the ad-hoc mode. However, using Wi-Fi Direct the user can scale and extend the network to multi-hops. Wi-Fi Direct enables users to display photos and videos on multiple screens.
3. Streaming Media: Wi-Fi Direct can be used in streaming applications where users can stream contents from streaming video server without directly connecting to the Internet. Users can form a P2P Group with another user who is connected to the Internet.
4. Online Gaming: Users can play multi-player games using Wi-Fi Direct when they make a P2P Group. Higher data rates of Wi-Fi, make Wi-Fi Direct an excellent choice for such applications.
5. Emergency Communication: Wi-Fi Direct can provide easy and flexible connection establishment during emergency communication for alert dissemination. Mobile applications like Firechat available on android, can be used to sent messages in event of emergency.
6. E-Commerce: Wi-Fi Direct based applications can be designed for sending advertisements locally. For example, shops can send local and targeted promotion messages, when a user is in proximity, in order to gain attention and thus increasing sales value.
7. Social Networking: Wi-Fi Direct Device and Service Discovery features allows Wi-Fi Direct to be used for social networking applications like proximity based chatting applications.

In this article, a brief introduction of Wi-Fi Direct technology and its applications are presented. To get more insights of the technical aspects and understanding the open research issues in Wi-Fi Direct, readers are encouraged to read our article [Link] in Journal of Networking and Computer Applications at Elsevier.