Abstract
We analyze the sum-rate performance of a multiantenna downlink system carrying more users than transmit antennas, with partial channel knowledge at the transmitter due to finite rate feedback. In order to exploit multiuser diversity, we show that the transmitter must have, in addition to directional information, information regarding the quality of each channel. Such information should reflect both the channel magnitude and the quantization error. Expressions for the SINR distribution and the sum-rate are derived, and tradeoffs between the number of feedback bits, the number of users, and the SNR are observed. In particular, for a target performance, having more users reduces feedback load.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1478-1491 |
| Number of pages | 14 |
| Journal | IEEE Journal on Selected Areas in Communications |
| Volume | 25 |
| Issue number | 7 |
| DOIs | |
| State | Published - Sep 2007 |
| Externally published | Yes |
All Science Journal Classification (ASJC) codes
- Computer Networks and Communications
- Electrical and Electronic Engineering
Keywords
- Broadcast channel
- Limited feedback
- MIMO
- Multiuser diversity
- Quantized feedback
- Random beamforming
- Scheduling
- Semi-orthogonal user selection
- Zero-forcing beamforming