Dual-mode satellite-cellular phones

Several mobile-satellite systems will be in commercial operation in the next 5 years. These systems will co-exist with terrestrial cellular systems augmenting their coverage and providing wide area roaming via the use of dual-mode (satellite-cellular) phones. The realization of dual-mode satellite-cellular handheld phones that are competitive in size and features with cellular phones is very dependent on the system design. This paper provides a perspective on the requirements and challenges in the design of such phones.