A server and a terminal enabling channel capacity estimation in a High-Speed Downlink Packet Access (HSDPA) network and a method of controlling the server and the terminal are provided. More particularly, when transmitting data between both terminals in an HSDPA network, a server end may transmit a packet pair of the same size and a client end may measure a time difference between the packet pair and thereby proceed filtering. Through this, it is possible to estimate the channel capacity. Therefore, it is possible to prevent data transmission from exceeding the channel capacity in the HSDPA to thereby prevent a packet loss and to effectively use a channel.