Apparatus and method for spreading/de-spreading data using pair of child orthogonal variable spreading factor codes

A spreading apparatus using a child orthogonal variable spreading factor (OVSF) code pair, comprising:

• a channel condition information receiving means for receiving and analyzing channel condition information including a channel condition metric wherein the channel condition metric is analyzed using equation:
• Channel_condition
• ⁢
• _metric
• ⁢
• (
• l
• ,
• k
• ,
• n
• )
• =
• ⁢
• E
• [
• Re
• ⁡
• [
• P
• r
• l
• ⁡
• [
• k
• +
• n
• ]
• ⁢
• P
• r
• l
• ⁡
• [
• k
• ]
• *
• ]
• P
• r
• l
• ⁡
• [
• k
• ]
• ⁢
• P
• r
• l
• ⁡
• [
• k
• ]
• *
• ]
• ,
• wherein
• Prl[k] denotes a kth receiving CPICH pilot symbol at an lth finger, Prl[k]=αl(k)ejφl(k)Pt[k] denotes Prl[k] with phase distortion and attenuation, and Pt[k] denotes a kth pilot symbol, Prl[k+n]=αl(k+n)ejφl(k+n)Pt[k] denotes a (k+n)th received CPICH symbol at a lth finger, and Re[Prl[k+n]Prl[k]*]=αl(k+n)αl(k)cos(φl(k+n))−(k)) denotes a real value of an inter symbol correlation that is a coherence time measuring metric, Prl[k]Prl[k]*=αl(k)2, and E[x] denotes an expectation value of x;
• a switch controlling means for receiving the channel condition metric from the channel condition information receiving means and transferring a data stream according to the received channel condition information;
• a first spreading means for receiving the data stream from the switch controlling means, and spreading the data stream using a single OVSF code;
• and
• a second spreading means for receiving the data stream from the switching controlling means, and spreading the data stream using a child OVSF code pair.