== [wiki:OFDM/MIMO MIMO OFDM] | [wiki:OFDM/MIMO#Documentation Documentation] | OFDM Frame Format ==

The frame format for the WARP MIMO OFDM core is based loosely on the frame format specified in the [http://ieeexplore.ieee.org/xpl/standardstoc.jsp?isnumber=17645&isYear=1999 IEEE 802.11a] wireless networking standard.

Each frame is divided into four sections, illustrated below:

[[Image(OFDM/MIMO/Docs/Images:FrameFormatOverview.png)]]

 * Preamble: a hard-coded 320-sample sequence used by the receiver for AGC, carrier frequency offset estimation and symbol timing estimation
 * Training: hard-coded OFDM symbols used for channel estimation. The number of training symbol periods is programmable per-packet.
 * Base Rate: a programmable number of OFDM symbols containing a packet's header, modulated using the user-specified base-rate modulation scheme.
 * Full Rate: a programmable number of OFDM symbols containing a packet's payload, modulated using the user-specified full-rate modulation scheme.

The WARP MIMO OFDM core supports both single (SISO) and two antenna (MIMO) modes. The frame formats for these two modes are detailed below.

== SISO Frame Format ==

[[Image(OFDM/MIMO/Docs/Images:SISO_Frame_Format.png)]]

== MIMO Frame Format ==

[[Image(OFDM/MIMO/Docs/Images:MIMO_Frame_Format.png)]]