A Novel MCS Selection Criterion for VOIP in LTE

This paper presents a novel modulation and coding scheme (MCS) selection method to optimize the performance of Voice over Internet Protocol (VoIP) semi-persistent scheduling in Long Term Evolution (LTE) downlink. In VoIP traffic, the packet length little changes during a certain period and the cost of resource for the packet is related to this length. We exploit the characteristics and propose to select a more reliable MCS with the same amount of resource to be allocated. This method can reduce the block error ratio (BLER) at the same time satisfy VoIP Quality-of-Service (QoS) requirements. Through system level simulations, the proposed MCS selection criterion is proved to yield nearly 15% capacity gain in LTE VoIP system compared with the conventional method.