Throughput is an important parameter that it is used to measure the performance of wireless local network (WLAN). In this research, we proposes a new discrete time Markov chain model to calculate the boundary of saturated and unsaturated throughput efficiencies in WLAN channel. Both throughput parameters are compared in fixed back off stages and fixed contention window sizes (FBFC) technique by applying the global balance equation concept in steady-state distribution of discrete time Markov chain model. Also, the collision resolution method of transmitted packets through WLAN channel uses the Binary Exponential Back off (BEB) algorithm based on Carrier Sense Multiple Accesses with Collision Avoidance (CSMA/CA) protocol. Our numerical results show that the throughput of unsaturated channel is higher than the saturated channel at light traffic load. On the contrary, the throughput of unsaturated channel is less than the saturated channel at high traffic loads condition.