[OpNet WLAN Model] BSS自动信道分配

frost.wrath

   
   



[color="#02368d"][OpNet WLAN Model] Auto Channel Allocation for BSS
Node name and modelbase station 2 : wlan2_router_adv  (referred to as 'base station')http_server : wlan_server_advWireless LAN MAC parametershttp_serverAttribute nameValueBSS Identifier1Channel settingAuto Assignedbase station (IF0 P0)Attribute nameValueBSS Identifier1Channel settingAuto Assignedbase station (IF1 P1)Attribute nameValueBSS Identifier3Channel settingAuto AssignedTraffic SourcesAn ip_traffic_flow demand is configured from 'base station' to 'http_server'.ip_traffic_flow profileAttribute nameValueTraffic (bits/sec)12,767Traffic (packets/sec)5Traffic MixAll ExplicitTraffic Start Time30Since hybrid (explicit and background) traffic doesn't work well in wireless radio scenarios currently, I choose 'All Explicit'.Simulation Run
   
   
Packet 63 and 67 are both generated by base station's
WLAN MAC module. And pk63 is transmitted by base station's transmitter
0 while pk67 is transmitted by transmitter 1.Two pieces of trace below show the creation of the 2 packets.    * Time   :  37.793641848372 sec, [37s . 793ms 641us 848ns 372ps]    * Event  :  execution ID (383), schedule ID (#408), type (stream intrpt), (Forced)    * Source :  execution ID (382), top.lab2.base station 2.ARP0 [Objid=1995] (processor)    * Data   :  instrm (1), packet ID (62), ICI ID (12)    > Module :  top.lab2.base station 2.wlan_mac_0_0 [Objid=1919] (processor)                +- op_pk_create_fmt (format_name)        |       format name      (wlan_mac)        |       packet ID        (63)        +-------   * Time   :  37.793641848372 sec, [37s . 793ms 641us 848ns 372ps]    * Event  :  execution ID (385), schedule ID (#411), type (stream intrpt), (Forced)    * Source :  execution ID (384), top.lab2.base station 2.ARP1 [Objid=2074] (processor)    * Data   :  instrm (1), packet ID (66), ICI ID (14)    > Module :  top.lab2.base station 2.wlan_mac_1_0 [Objid=1998] (processor)                +- op_pk_create_fmt (format_name)        |       format name      (wlan_mac)        |       packet ID        (67)        +-------Following the trace, we can find out the transmission frequency and bandwidth for the 2 packets.        | +- op_td_get_dbl (pkptr, tda_index)        | |       packet ID        (63)        | |       TDA attribute    (OPC_TDA_RA_TX_FREQ)        | |       TDA value        (2,426,000,000.0 Hz)        | +-------        |         | +- op_td_get_dbl (pkptr, tda_index)        | |       packet ID        (63)        | |       TDA attribute    (OPC_TDA_RA_TX_BW)        | |       TDA value        (22,000,000.0 Hz)        | +-------       | +- op_td_get_dbl (pkptr, tda_index)        | |       packet ID        (67)        | |       TDA attribute    (OPC_TDA_RA_TX_FREQ)        | |       TDA value        (2,421,000,000.0 Hz)        | +-------        |         | +- op_td_get_dbl (pkptr, tda_index)        | |       packet ID        (67)        | |       TDA attribute    (OPC_TDA_RA_TX_BW)        | |       TDA value        (22,000,000.0 Hz)        | +-------Since the 2 channels (channel 5 and channel 6) are overlapping, packets are considered to be in collision status. In inoise stage, we'll find the following trace: Kernel Action: Radio pipeline              Calling (inoise) pipeline stage              arriving noise packet (67)              earlier valid packet (63)                +- op_td_increment_int (pkptr, tda_index, value)        |       packet ID        (67)        |       TDA attribute    (OPC_TDA_RA_NUM_COLLS)        |       TDA value        (1)        +-------
All packets that are finished with receiving have bit errors,
overpassing the default ecc threshold (namely 0). As a result all
packets are dropped by the ecc pipeline stage, unable to reach MAC module or higher layers.According
to best-of-practice, I set channel 1 and 6 for the 2 BSS's
respectively. At this point the traffic is able to be received normally.

ConclusionSetting BSS identifier only cannot seperate transceivers in frequency domain.

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