Resources for WiFi

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IEEE 802.11 (WiFi) has been used in most of the laptops, smartphones, tablets. The widespread use of WiFi has led to extensive research interests in the area of localization, security, sensing and produced massive successful research outcomes. This paper summarizes some hardware and software resources for WiFi for the research purpose.

Strictly speaking, IEEE 802.11 is the standard by IEEE and WiFi is a trademark of the WiFi alliance. However, they are used interchangably in this post.

Standard

IEEE 802.11 standard defines the physcai layer and media access control (MAC) layer protocols. It has undergone a number of amendments in the last twenty years, since its first release in 1997. A complete list of the IEEE 802.11 amendments is summarized at wikipedia.

PHY Layer

The main physical layer amendments include 802.11b (1999, DSSS), 802.11a (1999, OFDM, 5 GHz), 802.11g (2003, OFDM, 2.4 GHz), 802.11n (2009, MIMO OFDM, high throughput), 802.11ac (2013, MIMO OFDM, very high throughput), 802.11 ax(est late 2019, high efficiency).

MAC Layer

WiFi use CSMA/CA as the MAC layer protocol.

  • Control frames
  • Management frames
  • Data frames

Testbed and Implementations

The commercial network interface cards (NICs) only provide received signal strength indicator (RSSI) but not channel state information (CSI). RSSI represents the received power which is averaged over a packet, thus it is a coarse grained parameter. On the other hand, CSI is a fine grained parameter, and offers detailed channel response over different frequencies/subcarriers, when OFDM-based technique is used. Since CSI is much more useful for innovative research, a (incomplete) list of testbed is given below.

USRP Software Defined Radio (USRP)

ZedBoard + FMCOMMS2/3/4 SDR

WARP 802.11 Reference Design

There is an 802.11 reference design implemented for WARP boards, which is compatible with the commercial WiFi. An experimental framework is implemented by Python for the research development. The available variables/parameters can be found here, among which the CSI is made public.

WARP is being actively used for research in many areas like power management, architectures for wireless receivers, physical layer algorithms, access protocols, routing and cognitive radios. A list of papers using WARP can be found at here.

Network Interface Cards

Please note PCI-e interface is required for these NICs.

Intel 5300 NIC

There is the Linux 802.11n CSI Tool for Intel 5300 NIC.

This Intel NIC together with the CSI tool have been used extensively by researchers and led to many excellent research papers. A list of the relevant publications can be found at link.

Atheros Chipsets

There is Atheros CSI Tool.

A list of the relevant publications can be found at here.

Software Tool

Matlab WLAN Toolbox

The WLAN Toolbox of Matlab is very powerful. There are many useful functions and examples. I strongly suggest to test your idea and algorithms using this Toolbox before you do it with real hardware.

Radiotap

  • What is radiotap? link

Scapy

Scapy is a Python program that enables the user to send, sniff and dissect and forge network packets. This capability allows construction of tools that can probe, scan or attack networks. (quoated from link)

There is a library supporting IEEE 802.11.