Ultra-Reliable Link Adaptation for Downlink MISO Transmission in 5G Cellular Networks

Abstract

This paper addresses robust link adaptation for a precoded downlink multiple input single output (MISO) system, for guaranteeing ultra-reliable (99.999%) transmissions to mobile users served by a small cell network (e.g. slowly moving machines in a factory). Effects of inaccurate channel state information (CSI) caused by user mobility and varying precoders in neighboring cells are mitigated. Both of these impairments translate to changes of received signal-to-noise plus interference ratios (SINRs), leading to CSI mispredictions and potentially erroneous transmissions. Knowing the statistics of the propagation channels and the precoder variation, backoff values can be selected to guarantee robust link adaptation. Combining this with information on the current channel state, transmissions can be adapted to have a desired reliability. Theoretical analysis accompanied by simulation results show that the proposed approach is suitable for attaining 5G ultra-reliability targets in realistic settings.

Fifth-Generation Control Channel Design: Achieving Ultrareliable Low-Latency Communications

“…One is related to the CQI decoding, i.e., decoding a CQI as a higher or a lower value. Another issue for the CQI report is the time gap between the channel measurement and the actual data transmission, during which the channel might change unfavorably [13]. Some of solutions for these issues are as follows: ■ Configurable CQI report: A wideband CQI is carried over the PUCCH using the same number of resources.…”

“…To compensate for the effects of the outdated CQI report, the gNB can consider the CQI report delay while selecting the MCS for data transmissions. In this regard, a more robust MCS is selected when there is a long delay between the CQI report and downlink transmission [13]. This requires providing additional information for the scheduler, such as delay and channel variations.…”

Enabling Ultra-Reliable and Low-Latency Communications through Unlicensed Spectrum

“…Recently, automated rate adaptation with limited feedback has been utilized to guarantee ultrareliability and achieve the minimized transmission delay. For example, in [5], a robust link adaptation is enabled to select suitable data rates for desired reliability (99.999%) and delay constraints. However, automated rate adaptation relies heavily on the accuracy of channel state information (CSI).…”

Statistical Analysis of Downlink Transmissions for Ultra-Reliable Low-Latency Communications

“…Another solution is considering the time gap while selecting the MCS. In this way, a more robust MCS is selected when there is a long time gap between the received CQI and data transmission instances [28].…”