Unstable Cisco Aironet 1231

Question

I have one Cisco Aironet 1231 access point. It does not use any kind of (server) functionality outside the Cisco device.
I have one SSID and uses WPA-PSK (TKIP).
The configuration seams wary straight forward, but something is wrong.
The access point seams to be unstable. The clients use long time to connect to the access point and it looses connection a lot of times a day. Can I do something to speed up the ?negotiation process? ?
What could be the course of instability?
The configuration was made with the ?web configurator?, but I have a SSH/telnet dump:
Best Regards
Martin
AP1#sh run
Building configuration...
Current configuration : 2227 bytes
version 12.3
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
hostname AP1
enable secret xxx
clock timezone GMT 1
ip subnet-zero
ip domain name mydom.com
aaa new-model
aaa group server radius rad_eap
aaa group server radius rad_mac
aaa group server radius rad_acct
aaa group server radius rad_admin
aaa group server tacacs+ tac_admin
aaa group server radius rad_pmip
aaa group server radius dummy
aaa authentication login eap_methods group rad_eap
aaa authentication login mac_methods local
aaa authorization exec default local
aaa accounting network acct_methods start-stop group rad_acct
aaa session-id common
dot11 ssid myssid
authentication open
authentication key-management wpa
guest-mode
wpa-psk ascii xxx
username Cisco password xxx
bridge irb
interface Dot11Radio0
no ip address
no ip route-cache
encryption mode ciphers tkip
ssid myssid
speed basic-1.0 basic-2.0 basic-5.5 6.0 9.0 basic-11.0 12.0 18.0 24.0 36.0 48.0 54.0
channel 2412
station-role root
no cdp enable
bridge-group 1
bridge-group 1 subscriber-loop-control
bridge-group 1 block-unknown-source
no bridge-group 1 source-learning
no bridge-group 1 unicast-flooding
bridge-group 1 spanning-disabled
interface FastEthernet0
no ip address
no ip route-cache
duplex auto
speed auto
no cdp enable
bridge-group 1
no bridge-group 1 source-learning
bridge-group 1 spanning-disabled
hold-queue 160 in
interface BVI1
ip address 192.168.1.105 255.255.255.0
no ip route-cache
ip http server
no ip http secure-server
ip http help-path http://www.cisco.com/warp/public/779/smbiz/prodconfig/help/eag
ip radius source-interface BVI1
access-list 111 permit tcp any any neq telnet
no cdp run
radius-server local
no authentication leap
no authentication mac
radius-server attribute 32 include-in-access-req format %h
radius-server vsa send accounting
control-plane
bridge 1 route ip
line con 0
access-class 111 in
line vty 0 4
access-class 111 in
sntp server 212.242.xx.207
sntp broadcast client
end
AP1#

Answer 1

A "stronger" (more gain) antenna probably won't help. An antenna that transmits with more gain also receives with more gain ..(basically, the same situation, but all of the signals are "louder")
The general remedy, aside from the obvious of going to the least populated channel or moving to the 802.11a band, is usually to add more access points, all using some flavor of "sector" antenna (and / or "patch" antennas) to localize the area of interest.
Because the antennas are covering a more specific area (and usually smaller area), it is usually the case that more APs are needed.
"Seeing" 20 APs is not that alarming ... check the signal strength of each, many will usually be well-below the level that would cause serious interference. The specific level will vary, depending on the location relative to the AP<->client relationship.
If you're seeing 20 APs, and their signal strength is roughly the same as your APs or a little lower, then you've got a problem that only a sectorized antenna system can cure.
Good Luck
Scott