Like　its　outdoor　counterpart　(e.g.,　GPS),　an　indoor　tracking　system　can　bring　about　disruptive　changes　in　how　we　live　and　work.　This　paper　proposes　a　location　and　tracking　system　using　a　single　WiFi　link　based　on　channel　state　information.　The　system　can　realize　real-time,　decimeter-level　localization　and　tracking.　In　this　system,　phase　calibration　and　static　path　elimination　are　realized　by　multiplying　the　conjugate　signals　of　different　antennas.　Then,　a　three-dimensional　MUSIC　algorithm　is　employed　to　estimate　the　angle　of　arrival　(AOA),　the　time　of　flight　(TOF),　and　the　velocity　of　a　target.　A　scheme　is　then　developed　to　adjust　the　MUSIC　search　range　and　reduce　the　computation　time　from　about　ten　hours　to　tens　of　seconds.　The　Widar2.0　data　set　from　Tsinghua　University　are　used　for　the　experiments;　the　proposed　system　is　found　to　have　an　average　tracking　error　of　0.68　m　in　the　three　environments　of　classroom,　office,　and　corridor,　which　is　better　than　the　existing　single　link　localization　and　tracking　system.