Hello, everyone! I am on my way to understand the HSDPA/HSUPA technologies. I have just started and came upon the topic of channelization code. I learned how these codes are generated - Hadamard code technique - and how they are used to transmit and retrieve the information of transmitters(like http://www.kynix.com/Product/Cate/694.html) . Further I read upon the 3GPP page that a major feature in HSDPA is thatthe channelization codes can be shared not only though code multiplexing, as in R99(UMTS), but also using time multiplexing. In time multiplexing one UE is allocated all the channelization codes in one TTI and another may use the resources in the next TTI. Now I have these doubts, which I am not able to get cleared even after referring various resources. 1) Why are we giving all of the Channelization codes to one UE. Wouldn't just one suffice? 2) What does sharing the code through code multiplexing mean. Is it different from code division multiplexing? How is the channelization code shared between different UE using code multiplexing? 3) Out of Time multiplexing and code multiplexing which is better and why and used in which case? For my first question,I will further explain my understanding. Please rectify wherever required. I understand that channelization codes are generated and shared with the UE so that it can decode the information sent to it inside the spreaded signal. Now when a code is determined for a UE for 1 TTI(in case of channelization code being shared by TDM tech) then why all the channelization code is shared with it. Is it so that it can receive lot such spreaded signal increasing the overall data rate at the UE. But then again cant all the information be spreaded wi how is the channelization code allocated through Time multiplexing and Code multiplexing. If Code Multiplexing = CDM. Then what does this phrase mean channelization codes can be shared not only though code multiplexing but also through time multiplexing. To allocate channel codes again codes are created!