Transmission strategies for correlated MIMO links with imperfect channel estimates

Abstract

Abstract-We investigate the transmit precoder design problem for a multiple input multiple output (MIMO) link with correlated receive antennas, considering the effect of channel estimation. We propose transceiver structures that are optimum in the sense of minimizing the total MSE and distributing the total MSE equally among the parallel data streams. We also investigate the problem of how the correlated MIMO link should distribute its total available power between power expended for channel estimation versus data transmission. The optimum power allocation problem between the training sequences for channel estimation and data transmission for the correlated MIMO link is shown to have a unique solution, that is different than the uncorrelated case. The performance of the system is observed to be more sensitive to transceiver design rather than the power allocation. The results demonstrate that the correlation structure of the MIMO link has a profound effect on the performance, and that the transceiver optimization should be done by taking both the correlation and the channel estimation process into account.

Rate Quantization and Cross-Layer Design of Multiple-Antenna Base Stations with Transmit MMSE and Imperfect CSIT

“…The linear weights W = {w k : k ∈ A} are selected to minimize the total normalized meansquare error J given by (4), where Y = [y 1 , ..., y |A| ] T and U = [u 1 , ..., u |A| ] T are the |A| × 1 vectors of received signals and encoded symbols for the selected users, Λ is the |A|×|A| diagonal matrix of the square-root of transmit powers √ p k .…”

“…3 Limited feedback refers to the system where only a limited number of bits is allowed to carry the CSIT feedback from the receiver to the transmitter. 4 Perfect limited feedback here means that the limited feedback obtained is assumed to be up-to-date without any error or delay.…”

“…Hence, it is important to take account of the CSIT errors in the cross layer design 2 to achieve robust performance. The effect of imperfect CSIT on point to point multiple input multiple output (MIMO) links has been investigated by [3], [4] and [5]. In [3], [5], Lloyd's algorithm is used to design the precoder for point-to-point MIMO link based on limited feedback.…”

“…In [8], a multi-user downlink zero-forcing based scheduling is analyzed using perfect limited feedback. 4 In [9], an opportunistic scheduling approach is proposed with perfect rate feedbacks from the mobiles. Yet, in all these cases, due to the perfect feedback assumption, there is no packet outage as long as the error correction code is sufficiently strong and hence, these works only considered ergodic capacity as the performance objective.…”

MIMO-CDMA systems: signature and beamformer design with various levels of feedback

“…In practical scenarios, CSI errors will be present and should be taken into account in system design. The effect of imperfect CSI on the sum capacity and the MSE of a MIMO link is studied in references [21]- [23]. [21] shows that, when estimation errors exist, the capacity has a lower bound, and the channel estimation error acts like additional Gaussian noise.…”