  As the explosive growth of the ISM band usage continues, there are many
scenarios where different systems operate in the same place at the same time.
One of growing concerns is the coexistence of heterogeneous wireless network
systems. For the successful deployment of mission-critical systems such as
wireless sensor networks, it is required to provide a solution for the
coexistence. In this paper, we propose a new scheme using inter packet delay
for the coexistence of IEEE 802.15.4 LRWPAN and IEEE 802.11b WLAN. To evaluate
the effectiveness of the proposed scheme, measurement and simulation study are
conducted using Qualnet 4.5 simulation software. The simulation results show
that the proposed scheme is effective in performance improvement for
coexistence network of IEEE 802.15.4 for various topologies.
