1. WiFi network connection function

  • Establish access point and wireless mesh network;
  • Build small wireless routers to connect to the Internet with nearby devices: provide public access to hot spots or create your own Wi-Fi hot spots;
  • Use ad-hoc mode to connect client to client to Wi-Fi devices without the need for a router.

1.1 Operating Principles

Wi-fi setup requires at least one Access Point (AP) and one or more clients (HI). The AP broadcasts Service Set Identifier (SSID) data packets through beacons every 100ms. The transmission rate of the Service Set Identifier (SSID) data packets is 1 Mbit/s and their length is relatively short. Therefore, this broadcast action has little impact on network performance. Because the minimum transmission rate of Wi-Fi is 1 Mbit/s, ensure that all Wi-Fi clients can receive the BROADCAST packets of this SSID. Then, clients can decide whether to connect to the AP of this SSID. The user can set which SSID to connect to. Wi-fi systems always open up their connection standards to clients and support roaming, which is the benefit of Wi-Fi. But it also means that one wireless adapter may outperform another in terms of performance.

2. WiFi Direct

  1. Wi-fi peer-to-peer (Wi-Fi peer-to-peer) is a software protocol that enables a wifi device to directly connect to another wifi device in a peer-to-peer manner for high-speed data transmission without having to use an Access Point. Based on the existing WiFi technology, WiFi Direct enables WiFi devices to connect wirelessly without routers or hotspots. This protocol was developed, supported and certified by Wi-Fi Alliance, and products that pass the certification will receive the Wi-Fi Certified Wi-Fi Direct logo.
  1. The Wi-Fi Direct architecture is higher than 802.11a, 802.11g, and 802.11n, but does not support 802.11b. Faster than the existing ad-hoc mode and also supports WPA2 encryption. The maximum transmission distance is 300 meters, and the maximum transmission speed is 250Mbps, using 2.4ghz and 5GHz bands. It supports one-to-one and one-to-many modes.

2.1 Advantages of wifi Direct

  • Mobility and portability: Wi-Fi Direct devices can connect to each other anytime, anywhere. Since no Wi-Fi router or access point is required, Wi-Fi devices can be connected from anywhere.
  • Instant availability: Users will be able to establish a Direct connection with the first Wi-Fi Direct authenticated device they bring home. For example, a newly purchased Wi-Fi Direct laptop can create a Direct connection to a user’s existing traditional Wi-Fi device.
  • Ease of use: Wi-Fi Direct Device Discovery and Service Discovery help users identify available devices and services and establish connections.
  • Simple and secure connection: Wi-Fi Direct The device uses Wi-Fi Protected Setup** to get the certificate and verify the WiFi Direct that is being searched.

2.2 Device Discovery

Scanning technology is adopted to discover and determine other Wifi Direct devices, and users can select the discovered devices to connect; If the target has not already joined the group, a new group will be formed, and if the target has joined the group, the Wifi Direct device being searched will try to join the existing group.

2.3 Service Discovery

Optional feature to notify other Wifi Direct devices of the services supported by the high-level application and to perform service discovery on other discovered Wifi Direct devices at any time (including before creating a connection). It is up to the vendor to implement service discovery.

2.4 Creating a Group

A group can be created with a Wifi Direct device; Groups can be created automatically between the two devices, the devices will negotiate to determine which device is responsible for managing the group, and the devices responsible for managing the group will determine whether the group is temporary (single instance) or permanent (multiple iterations).

2.5 Energy Saving Management

Wife Direct adopts P2P-PS and P2P-VMMPowerSave mechanism. The P2P specification introduces two energy-saving mechanisms: Opportunistic Power Save and Notice of Absence.

2.6 Wife Direct VS Bluetooth

Both are wireless network connection standards. Bluetooth is primarily used for wireless Personal Area Network (WPAN), which is best suited for connecting between personal devices. WiFi is mainly used to provide wireless area networks (WlAns) and also to connect devices. WiFi Direct enters Bluetooth’s established territory. But WifiDirect uses Wifi technology, which gives it better range and speed than Bluetooth, which has the advantage of lower power consumption.