How to reduce ping or lag for wireless internet in windows 7?

I have recently installed BSNL 4mbps connection with wireless modem.I play online shooting games like modern warfare 2,previously i used a direct cable internet it had much ping,i used TCPotimiser and reduced it ping very much,now it does not work on wireless intrernet as it does not have ip address,I fi try to enter IP,sub,gateway,DNS e.t.c.the internet does not work,so i can't enter IP address,I can't edit the TCP IP in rededit as i don't have IP address.Is there any other way to reduce the ping?I use windows 7 64-bit.thankz for helping