This work adopts a mobile social network in proximity (MSNP)-centric group touring service concept to share geo-points of interest's (POIs') data among mobile users belonging to the same touring group. In a group-based touring service, a mobile user can create a group in the MSNP that can consist of some clusters in which some members having the 3G/3.5G/4G cellular network service are selected as cluster leaders to enable their Wi-Fi hot spot functions as mobile proxies. After that, each group member can join one of the clusters by connecting with a cluster leader's Wi-Fi hot spot. Thereafter, each cluster leader downloads geo-POIs' data using 3G/3.5G/4G cellular network and then shares the downloaded POIs' data with its cluster members through its Wi-Fi hot spot. This work proposed a handoff mechanism such that each mobile user can handoff from its currently connected cluster to the other one that belongs to the same MNSP group. The main handoff concern is that each handheld device only allows a limited number of handheld devices to connect with its Wi-Fi hot spot at the same time. This work proposed a K-member-limited MSNP-based INter Group handoff scheme called K-MING to tackle the handoff problem. The performance analysis shows that K-MING for the group touring scenario has better performance for the sharing of geo-POIs' data downloading in terms of average power consumption and average downloaded data volume from 3G/3.5G/4G cellular network than that of the individual touring scenario. KEYWORDSclustering mechanism, data sharing, group-based touring service, location-based service, mobile social networks in proximity 600 /journal/spe Softw Pract Exper. 2018;48:600-620. HUANG AND MAI 601POI. 1,2 Two types of the LBS touring service are (1) individual-based and (2) group-based. The individual-based touring system considers issues that may exist when 1 person is using the LBS system for helping his touring. 3 The group-based touring system considers issues that may exist when a number of persons are using the LBS system to tour together. [4][5][6] Mobile social networks (MSNs), which are similar to online social networks, have raised enormous research studies. 7,8 Mobile social network integrates social networks and wireless communications in the mobile environments. It can be considered as an application or system that creates virtual communities and provides various contents among mobile users, for which mobile users can join any community that was created by other mobile users using any mobile device. Proximity service is a new service that allows neighboring mobile devices to use device-to-device (D2D) or terminal-to-terminal communication to share data with each other. 9,10 Some MSNs consider proximity, ie, nearby mobile users are interacting with each other directly using the D2D/terminal-to-terminal communication technique, which is called MSN in proximity (MSNP). 11,12 A mobile user can utilize either his handheld device's Bluetooth or Wi-Fi interface to detect proximate mobile users' handheld devices an...