Realization of Public M-Health Service in License-Free Spectrum

Public m-health is a new medical service under intensive development, which provides unobtrusive monitoring of people´s health conditions from anywhere at any time to enable detection of deteriorating health conditions before severe discomfort or disability occur. A key challenge in practical implementation of public m-health is the use of shared license-free spectrum by body area networks (BANs) to report sampled vital signs continuously and in real time. A cognitive medium access control method called centralized body area network access scheme (CBAS) is proposed in this paper to reduce access delay in a BAN in the presence of coexistent systems. By opportunistic extraction of idle spaces from a pool of orthogonal channels, CBAS dynamically adjusts a BAN´s channel access pattern according to the current interference environment, and improves the BAN´s visibility among coexistent networks. Performance of a BAN under CBAS is analyzed by modeling the system as a preemptive-resume priority queue. Numerical and simulation results show that the queuing delay and throughput of a BAN employing CBAS outperforms those of a BAN that utilizes a single channel statically, as channel access opportunities suffer less fragmentations and interruptions.