请问有用过ns2 802.11Ext的达人：如何设置通信距离？

Phy/WirelessPhyExt set CSThresh_                3.9810717055349694e-13    ;# -
94 dBm wireless interface sensitivity
Phy/WirelessPhyExt set Pt_                      0.1            ;#
equals 20dBm when considering antenna gains of 1.0
Phy/WirelessPhyExt set freq_                    5.9e+9
Phy/WirelessPhyExt set noise_floor_             1.26e-13            ;# -
99 dBm for 10MHz bandwidth
Phy/WirelessPhyExt set L_                       1.0                 ;#
default radio circuit gain/loss
Phy/WirelessPhyExt set PowerMonitorThresh_      3.981071705534985e-18   ;# -
174 dBm power monitor sensitivity (=level of gaussian noise)
Phy/WirelessPhyExt set HeaderDuration_          0.000040            ;#
40 us
Phy/WirelessPhyExt set BasicModulationScheme_   0
Phy/WirelessPhyExt set PreambleCaptureSwitch_   1
Phy/WirelessPhyExt set DataCaptureSwitch_       1
Phy/WirelessPhyExt set SINR_PreambleCapture_    3.1623;             ;# 5
dB
Phy/WirelessPhyExt set SINR_DataCapture_        10.0;              ;#
10 dB
Phy/WirelessPhyExt set trace_dist_              1e6                 ;#
PHY trace until distance of 1 Mio. km ("infinity")
Phy/WirelessPhyExt set PHY_DBG_                 0
Mac/802_11Ext set CWMin_                        15
Mac/802_11Ext set CWMax_                        1023
Mac/802_11Ext set SlotTime_                     0.000013
Mac/802_11Ext set SIFS_                         0.000032
Mac/802_11Ext set ShortRetryLimit_              7
Mac/802_11Ext set LongRetryLimit_               4
Mac/802_11Ext set HeaderDuration_               0.000040
Mac/802_11Ext set SymbolDuration_               0.000008
Mac/802_11Ext set BasicModulationScheme_        0
Mac/802_11Ext set use_802_11a_flag_             true
Mac/802_11Ext set RTSThreshold_                 2346
Mac/802_11Ext set MAC_DBG                       0
注意第一行，显然方法跟原来一样的。。。

看IP,大侠去了JW老师那里?