In this paper, an existing analytical model of WiMAX/WLAN heterogeneous network integration has been altered.We use two-dimensional Markov processes to model the dynamics of the WiMAX traffic and WLAN traffic.In our model, the user can remain static, move wvithin the cell or move out of the cell and step into a new cell.If the WLAN does not have enough resources to support a handoff connection request, the request will be transferred to WiMAX overlaid.Instead of the completely symmetric traffic and distributed coverage area in the original model, we have made the traffic asymmetric and the coverage area overlapped, which is a much more realistic scenario.The explicit expressions of various traffic arrival rates and performance metrics after the modification are also given.