Changes between Version 17 and Version 18 of OFDM/MIMO/Docs/AutoResponse

Timestamp:

Aug 29, 2009, 3:40:22 PM (15 years ago)

Author:

murphpo

Comment:

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OFDM/MIMO/Docs/AutoResponse

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-The OFDM core includes a subsystem which can automatically transmit a packet in response to a received packet. This behavior is ideal for implementing MAC protocols which require responses at fast time scales (like RTS-CTS or DATA-ACK exchanges). Both the conditions for responding and contents of the response packet are programmable at run-time.
+The OFDM core includes a subsystem which can automatically transmit a packet in response to a received packet. This behavior is ideal for implementing MAC protocols which require responses at fast time scales (like RTS-CTS or DATA-ACK exchanges). Both the conditions for responding and contents of the response packet are programmable from software. While this system is implemented in FPGA fabric, its behavior is programmed entirely by C code. Think of it as a MAC "accelerator"- MAC behaviors are specified in code but executed by dedicated hardware resources in the PHY.
 
-The auto response hardware consists of three parts- match units, actors and the header translator.
+The auto response hardware consists of three parts- '''match units''', '''actors''' and the '''header translator'''.
 
 === Match Units ===
-The auto response match units search for user-specified patterns in received headers. Each unit operates independently.
+The auto response match units search for user-specified patterns in received headers. Each unit operates independently. There are six match units in the current PHY.
+
+Each match unit searches for a sequence of 1, 2 or 3 bytes starting at some offset in each received header. Multiple match units can be used together to search for longer sequences.
 
 === Actors ===
-The actors are configured to trigger a transmission when a received packet meets programmed conditions, including any combination of match unit outputs.
+The actors are configured to trigger a transmission when a received packet meets programmed conditions. These conditions include any combination of match unit outputs, plus the Rx PHY status bits indicating the CRC status of received the received packet header and payload.
 
 '''Important:''' user code must guarantee that the conditions applied to each actor are mutually exclusive. No more than one actor should be triggered by a single packet reception. This requirement is '''not''' enforced in hardware. Results will be unpredictable if multiple actors are triggered at once. Unused actors should be disabled.
 
 === Header Translator ===
-The header translator is used to construct the header of an automatically transmitted packet using data from the header of the received packet which triggered the transmission.
+The header translator is used to construct the header of an automatically transmitted packet using data from the header of the received packet which triggered the transmission. This allows auto-transmitted packets to use values from received headers without having to read them into the user code. A simple example is populatng the destination address of an auto-transmitted ACK with the source address of the received DATA packet.
 
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