CQI reporting strategy for Multi-SIM UEs

UEs which support simultaneous activity from Multiple Active Subscriber
Identities (Multi-SIM) has gained popularity within the last years. Such UEs are forced to discard data on one of the SIMs when both try to access the Radio Frequency (RF) interface simultaneously, creating gaps in the data transfer. The discarded data due to Multi-SIM gaps, along with channel errors, significantly increase the probability of high latency data subframes. High latency increases the probability of data subframes being discarded. In this paper we present an algorithm with which it is possible to decrease the probability of discarded data subframes due to high latency. The algorithm takes advantage of the fact that the connections of each SIMs are unaligned and therefore gaps will only cover some timeslots partially. In such a case, it is possible to recover data using existing error correction coding, if the amount of corrupted bits corresponds to the error correction capability of the code. We investigate the performance of the algorithm using a link level simulator in respect to KPIs; overall throughput, decrease in subframe loss probability, and block error rate. The algorithm is tested in three different radio conditions as they comprise different restrictions to the algorithm. We show how the algorithm significantly decreases the subframe loss probability due to Multi-SIM, without significant impact on the overall throughput.