I. INTRODUCTION
   A. Related Works and Contributions
   B. Outline of the Paper

II. PUBLIC SAFETY NETWORKS
   A. LMRS Network
   B. LTE Broadband Network
   C. Major Challenges in PSNs

III. PUBLIC SAFETY SPECTRUM ALLOCATION IN THE UNITED STATES
   A. 700 MHz Public Safety Spectrum
   C. 900 MHz Public Safety Spectrum
   D. VHF and UHF Public Safety Spectrum
   E. 4.9 GHz Public Safety Spectrum

IV. LTE-BASED FIRSTNET PSN
   A. FirstNet Architecture

V. LMRS AND LTE CONVERGENCE

VI. MISSION-CRITICAL PTT OVER LTE

VII. COMPARISON OF LMRS AND LTE PSC
   A. Network Architecture
   B. Channel Configuration and Frame Structure

VIII. LMRS VS. LTE: SIMULATION RESULTS

IX. LMRS VS. LTE: SDR EXPERIMENTS

X. EMERGING TECHNOLOGIES FOR PSC

XI. PUBLIC SAFETY BROADBAND DEPLOYMENTS IN OTHER REGIONS OF THE WORLD

XII. ISSUES AND OPEN RESEARCH DIRECTIONS

XIII. CONCLUDING REMARKS