I. INTRODUCTION
Future wireless networks will be heterogeneous [1]. The heterogeneous wireless networks integrate different access networks, such as IEEE 802.15 WPAN, IEEE 802.11 WLAN, IEEE 802.16 WMAN, GPRS/EDGE, cdma2000, WCDMA and satellite network, etc. Selection of the most efficient and suitable access network to meet a specific application's QoS requirements has thus recently become a significant topic, the actual focus of which is maximizing the QoS experienced by the user. The main concept is that users will rely on intelligent network selection decision strategies to aid them in optimal network selection. At this point, it must be clarified that even if Quality of Experience (QoE) and Quality of Service (QoS), are not identical concepts, there are several cases where users' perception of a service can be estimated through using end-to-end QoS, as explained in [2]. Either way, as also stressed in [3], in QoE's case there is too much subjectivity which poses barriers to its use. A concrete definition of QoE is provided in [4].