Methods and devices for link adaptation under conditions of intermittent interference in wireless communication systems

摘要

Link adaptation of a downlink between an eNB and a User Equipment (UE) in an LTE system operating in unlicensed spectrum is based upon information in Channel Quality Indicator (CQI) reports which monitors and reports on an individual sub-frame periodically. If the downlink is subject to intermittent interference, the sub-frame reported on my not be affected and therefore the CQI will not reflect this. By reporting a CQI value for every sub-frame, intermittent interference will be detected. This information is used by the eNB to select an appropriate Modulation Coding Scheme (MCS) based on the channel conditions. The ratio between sub-frames affected by interference to those not affected by interference may also be calculated to determine which MCS is most appropriate. Alternatively, the CQI reports may be used to determine the duty cycle of the source of any intermittent interference and use the duty cycle information at the eNB to select a MCS. A higher order MCS will provide a higher throughput but will necessitate frequent retransmissions or a lower order MCS will require frequent retransmissions but will have the disadvantage of a lower throughput.