This paper proposes a practical throughput upper bound that considers physical layer techniques using adaptive modulation and coding (AMC) for orthogonal frequency division multiplexing (OFDM) multiple-input multiple-output (MIMO) multiplexing. The proposed upper bound is computed from the modulation and coding scheme (MCS) that provides the maximum throughput considering the required block error rate (BLER) at the respective received signal-to-noise power ratios as a constraint. Then, based on the practical throughput upper bound, we present the causes of impairment for selecting the best MCS based on the computed mutual information for OFDM MIMO multiplexing. More specifically, through the evaluations, we investigate the effect of MCS selection error on an increasing maximum Doppler frequency due to the round trip delay time and the effect of channel estimation error of maximum likelihood detection associated with reference signal based channel estimation.

LTE-Advanced supports asymmetric carrier aggregation (CA) to achieve flexible bandwidth allocation by applying different numbers of component carriers (CCs) between the downlink and uplink. This paper experimentally clarifies the achievable downlink throughput performance when uplink control information (UCI) feedback mechanism using the physical uplink shared channel (PUSCH), which enables minimization of the UCI overhead while maintaining the required reception quality, is applied in asymmetric CA. The laboratory experimental results show that the stable reception quality control of the channel quality information (CQI) with the target block error rate (BLER) of 10-1 to 10-2 is achieved irrespective of the average received signal-to-noise power ratio (SNR) when the control offset parameter of approximately 1.25 is used. We also show that the achievable downlink throughput when the CQI error is considered is almost the same as that in no CQI error case. Furthermore, based on the experimental results in a real field environment, a suburban area of Yokosuka city in Japan, we confirm stable adaptive modulation and coding (AMC) operation including target BLER control of the CQI on the PUSCH in asymmetric CA. The field experimental results also show that when CA with 5 CCs (90-MHz bandwidth) and 2-by-2 rank-2 multiple-output multiple-input (MIMO) multiplexing are employed in the downlink, the peak throughput of approximately 640Mbps is achieved even considering the CQI error.

This paper presents indoor experimental results on 4-by-2 multi-user (MU)-MIMO transmission with carrier aggregation (90-MHz bandwidth) achieving real-time 1-Gbps data transmission using adaptive modulation and coding (AMC) in the LTE-Advanced downlink employing OFDMA radio access. In the experiments, eigenvalue decomposition (EVD)-based channel state information (CSI) feedback based on subband unit for MU-MIMO operation and inter-user interference whitening filter applied before maximum likelihood detection (MLD) are employed to achieve such a high data rate with realistic numbers of transmitter and receiver antennas. The indoor experiments are conducted in a conference room under line-of-sight conditions with multiple reflected waves where one mobile station (MS) travels at walking speed and the other MS is static. The experimental results show that the total throughput for the 2 MSs is greater than 1Gbps at the average received signal-to-interference plus noise power ratio (SINR) of approximately 25 and 17dB for the first and second streams of each MS, respectively, when the moving speed is up to approximately 1km/h. The results also show that a centralized transmitter antenna arrangement is more effective in order to achieve a high data rate such as 1Gbps compared to a distributed antenna arrangement for the measurement environment.