Recently, there has been significant interest in the integration and co-existence of Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) with other Radio Access Technologies, like IEEE 802.11 Wireless Local Area Networks (WLANs). Although, the inter-working of IEEE 802.11 WLANs with 3GPP LTE has indicated enhanced network performance in the context of capacity and load balancing, the WLAN discovery scheme implemented in most of the commercially available smartphones is very inefficient and results in high battery drainage. In this paper, we have proposed an energy efficient WLAN discovery scheme for 3GPP LTE and IEEE 802.11 WLAN inter-working scenario. User Equipment (UE), in the proposed scheme, uses 3GPP network assistance along with the results of past channel scans, to optimally select the next channels to scan. Further, we have also developed an algorithm to accurately estimate the UE's mobility state, using 3GPP network signal strength patterns. We have implemented various discovery schemes in Android framework, to evaluate the performance of our proposed scheme against other solutions in the literature. Since, Android does not support selective scanning mode, we have implemented modules in Android to enable selective scanning. Further, we have also used simulation studies and justified the results using power consumption modeling. The results from the field experiments and simulations have shown high power savings using the proposed scanning scheme without any discovery performance deterioration.
 Recently commercial mobile phones have been shipped with integrated Wi-Fi NIC (Network Interface Card), while a fundamental barrier for easily using such Wi-Fi is its high energy cost for phone. We profile two integrated mobile phone Wi-Fi NICs and observe that the energy cost on PSM (Power Saving Mode) is greatly reduced, yet the scan state still costs most of the energy when it's not connected on discovering potential AP (Access Point). In this paper, we propose footprint, leveraging the cellular information such as the overheard cellular tower IDs and signal strength, to guild the Wi-Fi scan and thus greatly reduce the number of unnecessary scans through the changes and history logs of the mobile user's locations. Our experiments and implementation demonstrate that our scheme effectively saves energy for mobile phone integrated with Wi-Fi. Location based services (LBS) have generated a lot of interest in recent years, in the era of significant telecommunications competition. Mobile network operators continuously seek new and innovative ways to offer new services and increase the profit. In the days to come, location based service will be benefiting both the consumers and network operators. Mobile operators should consider various aspects when offering LBS, including network technology evolution, standardization, user acceptance, and the availability of attractive services. Many location-based services require the involvement of many different parties in order to provide the value added service. This paper presents current trends and requirements for LBS implementation in GSM, GPRS and UMTS networks.