  The new model of a quantum ring (QR) defined inside a nanowire (NW) is
proposed. The one-particle Hamiltonian for electron in [111]-oriented NW QR is
constructed taking into account both Rashba and Dresselhaus spin-orbit coupling
(SOC). The energy levels as a function of magnetic field are found using the
exact numerical diagonalization. The persistent currents (both charge and spin)
are calculated. The specificity of SOC and arising anticrossings in energy
spectrum lead to unusual features in persistent current behavior. The variation
of magnetic field or carrier concentration by means of gate can lead to pure
spin persistent current with the charge current being zero.
