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

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

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
[source:/ResearchApps/PHY/MIMO_OFDM/ofdm_tx_mimo_init.m#L48 ofdm_tx_mimo_init]

=== Training ===
A hard-coded OFDM symbols used for channel estimation. The number of training symbol periods is programmable per-packet.
[source:/ResearchApps/PHY/MIMO_OFDM/ofdm_tx_mimo_init.m#L37 ofdm_tx_mimo_init]

=== Base Rate ===
A programmable number of OFDM symbols containing a packet's header, modulated using the user-specified base-rate modulation scheme.
[source:/ResearchApps/PHY/MIMO_OFDM/ofdm_tx_mimo_init.m#L150]

=== Full Rate ===
A programmable number of OFDM symbols containing a packet's payload, modulated using the user-specified full-rate modulation scheme.
[source:/ResearchApps/PHY/MIMO_OFDM/ofdm_tx_mimo_init.m#L150]

== SISO Frame Format ==

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

== MIMO Frame Format ==

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