Abstract
We propose to combine the gains of a downlink power control and a joint multicode detection, for an HSDPA link. We propose an iterative algorithm that controls both the transmitted code powers and the joint multicode receiver filter coefficients for the high-speed multicode user. At each iteration, the receiver filter coefficients of the multicode user are first updated (in order to reduce the intercode interferences) and then the transmitted code powers are updated, too. In this way, each spreading code of the multicode scheme creates the minimum possible interference to others while satisfying the quality of service requirement. The main goals of the proposed algorithm are on one hand to decrease intercode interference and on the other hand to increase the system capacity. Analysis for the rake receiver, joint multicode zero forcing (ZF) receiver, and joint multicode MMSE receiver is presented. Simulation is used to show the convergence of the proposed algorithm to a fixed point power vector where the multicode user satisfies its signal-to-interference ratio (SIR) target on each code. The results show the convergence behavior for the different receivers as the number of codes increases. A significant gain in transmitted base station power is obtained.
Highlights
As wireless access to the internet rapidly expands, the need for supporting multirate services over limited spectrum increases
In order to achieve this goal, we propose in this paper to combine the downlink power control approach and the joint multicode detection, presented in [3], for the multicode user
We have analyzed the benefits of combining the downlink power control and the joint multicode detection for a multicode user
Summary
As wireless access to the internet rapidly expands, the need for supporting multirate services (voice, data, multimedia, etc.) over limited spectrum increases. In order to achieve this goal, we propose in this paper to combine the downlink power control approach and the joint multicode detection, presented in [3], for the multicode user. We propose an algorithm which controls both the transmitted code powers at the BS and the joint multicode receiver filters implemented in the mobile. The BS output power is adapted to the radio link conditions The implementation of this approach, in the HSDPA mobile, requires interference measurements for each code. The feasibility of the proposed approach is based on the transmission of the requested code power via a feedback link in order to update the BS output powers Such a feedback is considered in the HSDPA standard where the mobile transmits the channel quality indicator to the base station [2].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
