May be some one know !
I use DWL-7100(AP) with OpenWrt + DWL-AG660(STA) with XP+atheros drivers.

Distance between AP&STA 5 meters, but speed no more 16Mbit/s in simplex or 8 in duplex i don't have
whenever what protocol i use tcp or udp (samba, nfs, ssh).

May be some one know why?

Ill try play with chipset via iwpriv.

by default iwpriv ath1 --all & got

/etc/init.d/firewall stop

ath1      Available read-only private ioctl :
ath1      getoptie:
ath1      getchanlist:
ath1      getchaninfo:
ath1      get_mode:11g
ath1      get_authmode:5  
ath1      get_protmode:1  
ath1      get_mcastcipher:3  
ath1      get_mcastkeylen:16  
ath1      get_uciphers:8  
ath1      get_ucastcipher:0  
ath1      get_ucastkeylen:13  
ath1      get_keymgtalgs:2  
ath1      get_rsncaps:0  
ath1      get_hostroaming:1  
ath1      get_privacy:1  
ath1      get_countermeas:0  
ath1      get_dropunencry:0  
ath1      get_wpa:2  
ath1      get_driver_caps:1736631311  
ath1      get_wmm:0  
ath1      get_hide_ssid:1  
ath1      get_ap_bridge:1  
ath1      get_inact:300  
ath1      get_inact_auth:180  
ath1      get_inact_init:30  
ath1      get_abolt:0  
ath1      get_dtim_period:1  
ath1      get_bintval:100  
ath1      get_doth:1  
ath1      get_doth_pwrtgt:27  
ath1      get_compression:0  
ath1      get_ff:0  
ath1      get_turbo:0  
ath1      get_xr:0  
ath1      get_burst:0  
ath1      get_pureg:1  
ath1      get_ar:0  
ath1      get_wds:0  
ath1      get_bgscan:0  
ath1      get_bgscanidle:250  
ath1      get_bgscanintvl:300  
ath1      get_mcast_rate:1000  
ath1      get_coveragecls:0  
ath1      get_countryie:0  
ath1      get_scanvalid:60  
ath1      get_regclass:0  
ath1      get_dropunencea:0  
ath1      get_shpreamble:1  
ath1      get_rssi11a:24  
ath1      get_rssi11b:24  
ath1      get_rssi11g:24  
ath1      get_rate11a:48  
ath1      get_rate11b:10  
ath1      get_rate11g:18  
ath1      get_uapsd:1  
ath1      get_sleep:0  
ath1      get_eospdrop:0  
ath1      get_markdfs:1

next i add in /lib/wifi/madwifi.sh following strings

         #config_get rssg "$vif" rssi11g
        #[ -n "$rssg" ] && iwpriv "$ifname" rssi11g "$rssg"
        
        #config_get ratg "$vif" rate11g
        #[ -n "$ratg" ] && iwpriv "$ifname" rate11g "$ratg"
        
        #config_get rssb "$vif" rssi11b
        #[ -n "$rssg" ] && iwpriv "$ifname" rssi11b "$rssb"
        
        #config_get ratb "$vif" rate11b
        #[ -n "$ratb" ] && iwpriv "$ifname" rate11b "$ratb"

        config_get_bool doth "$vif" 80211h
        [ -n "$doth" ] && iwpriv "$ifname" doth "$doth"

        config_get_bool comp "$vif" compression
        [ -n "$comp" ] && iwpriv "$ifname" compression "$comp"

        config_get_bool burst "$vif" bursting
        [ -n "$burst" ] && iwpriv "$ifname" burst "$burst"

        config_get_bool trb "$vif" turbo
        [ -n "$trb" ] && iwpriv "$ifname" turbo "$trb"
        
        config_get_bool ar "$vif" armode
        [ -n "$ar" ] && iwpriv "$ifname" ar "$ar"

        config_get_bool xr "$vif" xrmode
        [ -n "$xr" ] && iwpriv "$ifname" xr "$xr"

        config_get_bool ff "$vif" fastframes
        [ -n "$ff" ] && iwpriv "$ifname" ff "$ff"

        config_get_bool wmm "$vif" wmm
        [ -n "$wmm" ] && iwpriv "$ifname" wmm "$wmm"

and 

         
//in setting on both sides fragmentation & RTS set like this 
option frag 2346
option rts 2346

// signal level on STA -56dB & noise -95dB
option txpower 18

//set best or current speed e.g. 54 or 48, but nothing happen, connection speed showing on STA 
//setups by signal, but in reality it defferent
option rate best
    
//i'll try find some thing what means this settings, but nothing found & just play with this
// but more than unstability signal & connection, dont have
#option rate11g 48
#option rssi11g 24
#option rate11b 48
#option rssi11b 24
    
//addition for support 802.11h
option 80211h 1

// add suppost fast frames, strange, but by default it option off 
option fastframes 1

//hardware QOS, dont do anything, needed play with setting, when off allequal i'll have 16Mbit simplex
option wmm 1

//compression frames by chipset, not CPU, by default off, strange,  not add speed  
option compression 1

//gluing packets, add some speed if lenght of packets small by default off, strange 
option bursting 1

// turbo mode, setup, in Atheros supplicant show that connection support static turbo, but
// in reality speed not up
option turbo 1

//add suuport to regulate static & dynamic turbo
option armode 1

// addition low rate support for STA up sensetive to -105dB & support speed connection 0,25Mbit/s
// ill enable it, but in atheros supplicant not show support XR mode
option xrmode 1

Please ! Help! May be ill do something wrong?
May be any one have solution?
With regards, Dmitry.