988 research outputs found
Rate Analysis of Two-Receiver MISO Broadcast Channel with Finite Rate Feedback: A Rate-Splitting Approach
To enhance the multiplexing gain of two-receiver Multiple-Input-Single-Output
Broadcast Channel with imperfect channel state information at the transmitter
(CSIT), a class of Rate-Splitting (RS) approaches has been proposed recently,
which divides one receiver's message into a common and a private part, and
superposes the common message on top of Zero-Forcing precoded private messages.
In this paper, with quantized CSIT, we study the ergodic sum rate of two
schemes, namely RS-S and RS-ST, where the common message(s) are transmitted via
a space and space-time design, respectively. Firstly, we upper-bound the sum
rate loss incurred by each scheme relative to Zero-Forcing Beamforming (ZFBF)
with perfect CSIT. Secondly, we show that, to maintain a constant sum rate
loss, RS-S scheme enables a feedback overhead reduction over ZFBF with
quantized CSIT. Such reduction scales logarithmically with the constant rate
loss at high Signal-to-Noise-Ratio (SNR). We also find that, compared to RS-S
scheme, RS-ST scheme offers a further feedback overhead reduction that scales
with the discrepancy between the feedback overhead employed by the two
receivers when there are alternating receiver-specific feedback qualities.
Finally, simulation results show that both schemes offer a significant SNR gain
over conventional single-user/multiuser mode switching when the feedback
overhead is fixed.Comment: accepted to IEEE Transactions on Communication
- …