Changes between Version 12 and Version 13 of 802.11/MAC/Upper


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Timestamp:
Aug 2, 2013, 1:20:47 PM (11 years ago)
Author:
chunter
Comment:

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  • 802.11/MAC/Upper

    v12 v13  
    33[[TracNav(802.11/TOC)]]
    44
    5 = High-level MAC Description =
     5= Upper-level MAC Description =
    66
    7 The high-level MAC is responsible for inter-packet states that are not time critical. The state machine implemented by the high-level MAC has 6 states: {{{Idle}}}, {{{MPDU Tx}}}, {{{MPDU Rx}}}, {{{Ethernet Tx}}}, {{{Ethernet Rx}}}, and {{{Scheduled Event}}}.
     7The upper-level MAC is responsible for inter-packet states that are not time critical. The state machine implemented by the upper-level MAC has 6 states: {{{Idle}}}, {{{MPDU Tx}}}, {{{MPDU Rx}}}, {{{Ethernet Tx}}}, {{{Ethernet Rx}}}, and {{{Scheduled Event}}}.
    88
    99[[Image(wiki:802.11/files:wlan_mac_cpu_high_overview.png, width=800)]]
    … …  
    1111== States ==
    1212
    13  * {{{Idle}}}: This state is the default state where no actions are performed by the high-level MAC. All other states return to {{{Idle}}} when completed.
     13 * {{{Idle}}}: This state is the default state where no actions are performed by the upper-level MAC. All other states return to {{{Idle}}} when completed.
    1414
    1515 * {{{MPDU Tx}}}: This state handles the transmission of wireless MPDUs from a transmit queue.
    … …  
    3131== State Transitions ==
    3232
    33  * {{{Idle}}} → {{{MPDU Tx}}}: This transition occurs when two conditions are met: (a) The [wiki:../Low low-level MAC] has indicated that it is ready to receiver another packet for wireless transmission and (b) the transmit queue in the high-level MAC contains a packet that needs to be sent.
     33 * {{{Idle}}} → {{{MPDU Tx}}}: This transition occurs when two conditions are met: (a) The [wiki:../Lower lower-level MAC] has indicated that it is ready to receiver another packet for wireless transmission and (b) the transmit queue in the upper-level MAC contains a packet that needs to be sent.
    3434
    35  * {{{Idle}}} → {{{MPDU Rx}}}: This transition occurs when the [wiki:../Low low-level MAC] has indicated that a reception has occurred with the following criteria: (a) the received packet is not a control packet (e.g. ACK, RTS, CTS) and (b) the received packet has a receiver address that is either a broadcast packet or a unicast packet whose address matches the MAC address of the node running this software.
     35 * {{{Idle}}} → {{{MPDU Rx}}}: This transition occurs when the [wiki:../Lower low-level MAC] has indicated that a reception has occurred with the following criteria: (a) the received packet is not a control packet (e.g. ACK, RTS, CTS) and (b) the received packet has a receiver address that is either a broadcast packet or a unicast packet whose address matches the MAC address of the node running this software.
    3636
    3737 * {{{MPDU Rx}}} → {{{Ethernet Tx}}}: This transition occurs when a wireless MPDU data reception occurs that should be de-encapsulated and via Ethernet. ''Note: Unlike the {{{MPDU Tx}}} state, the {{{Ethernet Tx}}} state does not employ a queue. As such, it can be directly accessed from the {{{MPDU Rx}}} state without transitioning through {{{Idle}}}. There is a good reason for this asymmetry: even at the fastest 802.11g rates, wireless packets are much slower than gigabit-per-second wired packets. When receiving a wireless packet, there is enough time to directly transmit a wired packet without halting the next wireless reception. This is not the case for wired receptions, so they must be queued in order to mitigate dropping packets during bursty Ethernet arrivals.''