BCM4330 Preliminary Data Sheet
MAC Features
TXE
The transmit engine (TXE) constitutes the transmit data path of the MAC. It coordinates the DMA engines to
store the transmit frames in the TXFIFO. It interfaces with WEP module to encrypt frames, and transfers the
frames across the MAC-PHY interface at the appropriate time determined by the channel access mechanisms.
The data received from the DMA engines are stored in transmit FIFOs. The MAC supports multiple logical
queues to support traffic streams that have different QoS priority requirements. The PSM uses the channel
access information from the IFS module to schedule a queue from which the next frame is transmitted. Once
the frame is scheduled, the TXE hardware transmits the frame based on a precise timing trigger received from
the IFS module.
The TXE module also contains the hardware that allows the rapid assembly of MPDUs into an A-MPDU for
transmission. The hardware module aggregates the encrypted MPDUs by adding appropriate headers and pad
delimiters as needed.
RXE
The receive engine (RXE) constitutes the receive data path of the MAC. It interfaces with the DMA engine to
drain the received frames from the RXFIFO. It transfers bytes across the MAC-PHY interface and interfaces with
the WEP module to decrypt frames. The decrypted data is stored in the RXFIFO.
The RXE module contains programmable filters that are programmed by the PSM to accept or filter frames
based on several criteria such as receiver address, BSSID, and certain frame types.
The RXE module also contains the hardware required to detect A-MPDUs, parse the headers of the containers,
and disaggregate them into component MPDUS.
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BROADCOM
BCM4330 Preliminary Data Sheet
April 28, 2011 • 4330-DS304-RI
Page 88
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