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. Further I read upon the 3GPP page that a major feature in HSDPA is that the 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.
- Why are we giving all of the Channelization codes to one UE. Wouldn't just one suffice?
- 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?
- Out of Time multiplexing and code multiplexing which is better and why and used in which case?