A stochastic-modeling approach to MAC coexistence of LTE-U and WiFi
Nazanin Rastegardoost, Bijan Jabbari · 2017
LTE in unlicensed spectrum, also referred to as LTE-U, is a promising solution introduced towards capacity enhancement and efficient spectral utilization through data offloading in the 5GHz unlicensed spectrum. This is especially applicable to LTE operated small cells, which are supposed to boost capacity and expand coverage as a second tier of cellular networks, by allowing seamless flow of data across both licensed and unlicensed bands via a unified core network. To ensure this, fair and stable coexistence with incumbent technologies, most important of which is WiFi, is crucial. In this paper, considering the dynamic and bursty nature of WiFi traffic, we propose an analytical framework based on Bivariate Markov Processes to stochastically characterize the temporal activity of WiFi network in the unlicensed band. In particular, we use Markov Modulated Batch Poisson Processes (MMBPP) to formulate the idle gaps, aka WiFi white spaces, by capturing the underlying states of the WiFi network, as well as the group packet arrivals. Relying on this model, we investigate the possibilities of LTE-U opportunistically accessing the WiFi channel, so as to fully utilize white spaces, while ensuring a fair coexistence. Simulation results based on developed models using NS3 validate the accuracy of our analytical model and demonstrate the potential opportunities available for LTE-U exploitation.