Multi-Carrier Transmission with Limited Feedback: Power Loading over Sub-Channel Groups

— Feedback of channel state information (CSI) enables a multi-carrier transmitter to optimize the power allocation across sub-channels. We consider a single user feedback scheme in which the entire set of sub-channels is evenly divided into smaller groups of sub-channels, and the receiver requests the use of a particular group if the gain of every sub-channel in the group is above a threshold. The transmit power is then uniformly spread across the requested sub-channel groups. The amount of feedback is therefore controlled by the group size and the threshold. For this scheme, we characterize how the channel capacity scales with the number of sub-channels N as a function of the feedback rate. We then consider transmission over a block fading channel, assuming that each coherence block contains both feedback and data transmission. We optimize the fraction of feedback overhead as a function of the number of feedback bits per channel use and coherence time. Numerical results show that th...

• Type: Conference
• Year: 2008
• Where: ICC
• Authors: Manish Agarwal, Dongning Guo, Michael L. Honig
• Keywords: Channel State Information, Communications, Feedback, ICC 2008, User Feedback Scheme