Innovative technology has made it possible to dramatically change the social and economic environment. In particular, 5G mobile communication technology that radically improves the performance of current technology can renew urban infrastructure, public services, and citizens' lives for the implementation of smart spaces. Although new services need to be generated by such innovative technology, existing technology-based approaches have mostly relied on the intuition of experts rather than a systematic approach. Thus, this paper aims to present a method and process by which technology-based new ideas using 5G mobile communication technology are generated to realize a connected environment by focusing on technological functions as well as customer value. First, the relationships among technology, value, and service are defined through morphology analysis. Second, service opportunities are identified by developing a transformed buyer-utility map in the smart space environment. After mapping the established services, candidate cells for a new service were identified as vacant cells in the map with the removal of technically unnecessary candidates based upon the pre-defined relationship. Third, a new service idea is generated by modifying/extending candidates concretely through an ERRC (Eliminate, Reduce, Raise, Create) framework. Value factors are determined in advance and shown in the As-Is value curve representing the current status. The current level in the curve is then compared at an industrial level and value factors are chosen to newly modify or create. As a result, the To-Be curve is established and leads to a new service idea. It can be regarded as a useful tool for mobile carriers to plan new business models for smart spaces with adequate technology and market feasibility.