Yes Andy, you are talking with the reference of 8051, there is a serial port in 8051, but i am using AT89c51, i dont think that there is any serial port in it.
And i am recieving synchronous data, and i have solved the problem of clock in it,

but real problem is if there is no serial port in AT89c51 then how can microcontroller recieves serial data from a standalone device(it can be any device which give ouput data to its serial port and i has to send this data to microcontroller from serial port)