Performance Evaluation and Analysis of Switching Algorithms in MIMO-OFDM System with Ideal and Non-Ideal CSI

Abstract

In this paper we analyzed the bit error rate performance of a switching algorithm between spatial multiplex-ing and diversity for an OFDM MIMO system with ideal channel state information. The effect of channel estimation error was studied and we verified by simulations that the spatial multiplexing outperforms the switching algorithm. Given that the switching algorithm is based on the comparison of the channel matrix Demmel condition number to a threshold, its accuracy is compromised when channel estimation error in-creases. As a first intuitive solution, we proceeded to the adaptation of the threshold, but this didn’t lead to a pertinent improvement for the main reason that channel estimation errors did affect the MIMO techniques which use different constellation. Based on that, we proposed a new estimation technique that improved the bit error rate performance significantly

A novelOFDMswitching algorithm for symmetric and asymmetricMIMOarchitectures

“…Study of switching performance in the presence of channel estimation errors has been done in. 21 To summarize, we 1. Review the DCN-based switching algorithm and we show its limitation when increasing the number of receive antennas.…”

“…For switching algorithms, different selection metrics were proposed to choose the appropriate MIMO technique according to the channel state 12‐21 . Among these metrics, the Demmel condition number (DCN) was considered as the simplest criterion that was concluded based on the minimum Euclidean distance (MED) 12,16 .…”

“…At present, perfect channel knowledge is assumed at the receiver. Study of switching performance in the presence of channel estimation errors has been done in 21 …”

Adaptive Pilot Pattern for Massive MIMO Systems

“…The first part is at the transmitter, where a pilot sequence is assigned to each user. Then, it is inserted in the available resources among the data following a specific pattern [8]. The second part is at the receiver.…”

“…The second part is at the receiver. Channel coefficients that correspond to the pilots' positions are estimated using several algorithms such as least-square (LS) [9], minimum mean-square error (MMSE) [9], and robust channel estimation [8]. Finally, they are interpolated among the unknown coefficients that correspond to the data positions.…”