hello

I'm broadcasting a wireless internet to 20 clients,and I'm using pppoe , but some one is broadcasting with the same SSID as mine and with many different mac addresses , many of my clients have a bad net and disconnecting many times and tow of them even don't connect to my network ...

so,what you think i can do to solve this problem ?

PS :
i can't hide my signal because i need new client to know me and even if i change it he will know it

my clients are using 2.4MHz Grid like this
hxxp://dmsichina.com/grid/SP242409-400.jpg

And i'm using omni antenna to broadcast

i search a lot for a solution for this problem and even talked with many people in yahoo chat rooms and they all say that i must broadcast with a stronger signal , the problem is there is a high noise in my area and if i did this my net will be so slow ...

I don't know if you need other information ,best regards