Admission control design for integrated WLAN and OFDMA-based cellular networks

We propose a QoS-aware admission control scheme (ACS) considering slow and fast calls for the integrated WLAN and OFDMA-based cellular network where only slow calls are allowed to connect with WLAN to maintain low handover overhead. The proposed ACS allows efficient traffic offloading from the macrocell to WLAN and considers QoS requirements for users in terms of minimum rates in all regions. The fractional frequency reuse (FFR) technique is assumed to be employed for interference mitigation in the cellular network. We also propose a novel bandwidth (BW) borrow-return strategy in the proposed ACS to improve the system performance. We then develop an analytical model to derive the blocking probabilities for calls in different areas. Numerical results demonstrate the performance enhancement of the ACS with the BW borrow-return strategy and the usefulness of the proposed analytical model in determining the size of WLAN offloading region.