Modeling and Analyzing LTE Licensed Assisted Access Network with Capture Effect

The coexistence performance of LTE-licensed assisted access (LAA) and WiFi networks has been extensively investigated. However, these works ignore capture effect, which is the phenomenon that the strongest signal may still be successfully received when more than two signals are transmitted simultaneously on the same channel, and which may occur more frequently in the coexistence scenario than in the pure WiFi network. This may lead to very large deviation in the coexistence performance evaluation. In the paper, we deeply investigate the coexistence performance of LAA and WiFi networks with the capture effect. More specifically, a capture model for more than two signals is first proposed in the coexistence scenario, and the capture probability is derived. Then the LAA access schemes are modeled as a new two-dimensional discrete Markov model integrating with the capture effect. A large number of simulation and numerical results verify the validity of the proposed Markov chain and capture model. The results also show that the capture effect can not only significantly decrease the collision probability but also increase LAA and WiFi throughput as well as total throughput. All these results prove the necessity of considering the capture effect in coexistence performance evaluation.