wiki:802.11

Version 1 (modified by chunter, 8 years ago) (diff)

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802.11 Reference Design

The 802.11 Reference Design implements a compatible 802.11 PHY and MAC on WARP v3 hardware. For details on the MAC and PHY features that are implemented, please see the FAQ. By default, the 802.11 Reference Design implements an Access Point with WLAN to wired LAN integration portal. By plugging the ETH A connector on the board into a router (or other device with DHCP server), then any 802.11 device can connect to the custom WARP AP and access the wired network (typically the Internet).

The WARP 802.11 Reference Design is supported on Mango WARP v3 hardware. Previous generations of WARP hardware are not supported, as the design requires tools and FPGA features which preclude porting to Virtex-II Pro or Virtex-4 FPGAs. The Research License? requires the design only be used on hardware supplied by Mango Communications.

No image "802_11_RefDes_Overview.png" attached to 802.11

The 802.11 Reference Design consists of 4 key hardware components that, together, implement the 802.11 PHY, MAC and some of the networking layer.

Hardware Components

  1. CPU_HIGH (mb_high): a high-level processor for performing inter-packet tasks that are not time critical. For example, this processor handles 802.11 associations with stations and handles the periodic transmissions of beacon frames. Additionally, this processor handles Ethernet receptions and transmissions. The wlan_mac_ap software project implements a portal to integrate the WLAN with a Wired LAN as specified in Annex P of the 802.11-2012 standard.
  1. CPU_LOW (mb_low): a low-level processor for handling intra-packet behaviors that are time critical. For example, this processor runs code that is responsible for constructing outgoing ACK frames within a SIFS interval following the last byte of a reception on the wireless medium. It is also responsible for handling retransmissions and modifying the 802.11 contention window as appropriate. The wlan_mac_dcf software project is an implementation of Section 9.3.1 of the 802.11-2012 standard. Inter-processor communication between CPU_HIGH and CPU_LOW is handled by an AXI Mailbox and mutual exclusion is handled by an AXI Mutex.
  1. MAC DCF (wlan_mac_dcf_hw): a hardware peripheral core that acts as the interface between the physical layer and any C code that runs in the processors. It also assists in managing the DCF transmit state machine by automatically beginning timeouts after unicast transmissions, beginning backoff intervals after DIFS intervals following medium idle indications, and other timing-critical functions. It also manages the virtual CS of the system, automatically interpreting the duration field of receptions and updating the NAV. Furthermore, this core is responsible for the automatic transmission of packets after valid-FCS receptions, provided the CPU_LOW enables that feature and constructs the outgoing frame prior to the time in which it should transmit (generally a SIFS).
  1. PHY TX/RX: These peripheral cores implement the physical layer behavior specified in Section 18 of the 802.11-2012 standard. Details are available in the FAQ.

Getting Started with the 802.11 Reference Design

  1. Plug ETH A from a WARP v3 board into a router whose WAN port is connected to the Internet. The 802.11 Reference Design is not a router -- it does not have a DHCP server to issue IP addresses to associated stations. It will, however, pass DHCP requests and responses through its Ethernet portal, so connecting WARP v3 to a router will allow DHCP to occur on client stations.
  2. Download the 802.11 Reference Design and program a WARP v3 board with the provided bitstream.
  3. Use any 802.11 device (such as a computer or smartphone) to join the unsecured network with SSID of "WARP." At this point, the 802.11 device should be able to access the network.