SUCCESSIVE TRANSMISSION THROUG USART

[jaycec]

Hi Forum,
if we are transmitting data successively through usart do we have to put some delay between to successive transmission to give pic some settilment time?I am asking this because,in my project i am using rf transmitter and receiver and at receiver side i have a usb interface also.I heard that for reliable transmission through rf module we have to first send some random value and then a byte that tells the receiver that a valid data byte is following.but the problem is when i transmitted random value,identification byte and data byte without any delay between transmission they all get mixed up,but when i add delay they worked fine.I did all this by connecting receiver and transmitter pic by wire.But i have to use rf module now,if i continue using delay between transmission is there a possiblity that rf receiver piks up some noise in between the delay time?please helpme