Impact of Capture Effect on LTE-Licensed Assisted Access Networks

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. Therefore, in this paper, the coexistence performance of LAA and WiFi networks with the capture effect is deeply investigated. More specifically, a capture model for more than two signals is firstly proposed in the coexistence scenario, and the capture probability is derived. Then the LAA access scheme is modeled as a new two-dimensional discrete Markov model with the capture effect, where the decrease of the backoff counter depends not only on the idle time slots but also on the time slots in which capture effect occurs. Finally, the expressions for coexistence performance are derived. A large number of simulation and numerical results verify the validity of the proposed Markov chain and capture model. The results prove the necessity of considering the capture effect in coexistence performance evaluation.