Recently standards essential patent (SEP) is key issue in the global information and communication technology (ICT) market and also standards setting organizations (SSOs). In this context, we briefly survey recent litigation case regarding SEP and related discussion in the ITU-T. After that, we analyze SEP trend in the IEEE-SA (Standards Association) based on IEEE-SA records of IEEE standards-related patent letters of assurance (LOA) as a case study. Based on the analysis result, we examine each country's SEP position developed in this paper which indicates the degree of a country's standardization activity linked to patents. Finally, we will seek standardization strategy coping with the rapidly changing environment.