sources would create code blocking. The resource manager functionality has functions to optimise the code tree. Another step after spreading is scrambling. The baseband bit sequence is scrambled using a scrambling code. This code is used to separate UEs and BSs. This operation does not change the signal bandwidth but only separates the signals from different sources. The chip rate is already achieved in spreading by channellisation codes and the symbol rate is not affected by scrambling. Radio Network Planning and Optimisation SF=16 SF=256 C16(0)=[ Cg(0)=[11111111] C16(1)=[ C4(0)=[1111] C16(2)=[ C (1)=[1111-1-1-1-1] C2(0)=[11] C16(3)=[ C16(4)=[ C (2)=[11-1-111-1-1] C16(5)=[ C4(1)=[11-1-1] C16(6)=[ C (3)=[11-1-1-1-111] C16(7)=[ Co(0)=[1] C16(8)=[ Cg(0)=[1-11-11-11-1] C16(9)=[ C4(2)=[1-11-1] C16(10)=[ C (5)=[1-11-1-11-11] C2(1)=[1-1] C16(11)=[. C16(12)=[ C (6)=[1-1-111-1-11] C16(13=[ C4(3)=[1-1-11] C16(14)=[ Cg(7)=[1-1-11-111-1] C16(15)=[ Figure 2.7 Code tree Processing Gain Due to spectral spreading of the user signal, the D-CDMA system is more resistant to interference. This is because, with respect to the interference signal, the multiplication code used at the receiver is similar to the one used at the transmitter. In an effort to understand this, assume that the user signal during the course of spreading is multiplied by a factor of, say, eight. This means that the signal increases by a factor of eight with respect to the interfering signal from another user. This is called the processing gain. Processing gain is a power density factor that tells how much less energy in W/Hz is required to transmit information on a wideband signal in comparison with transmitting the same information on a narrowband signal. According to information theory the energy X time X frequency band required to transmit an information bit is constant. Spreading the narrowband signal into a wideband signal gives the processing gain. The greater the difference between the narrowband bit rate and the wideband chip rate the greater the proce