We report four different types of plasma waves detected in and near the dayside polar cap boundary layer (PCBL) region at high altitudes (>6 RE). One wave type is narrowband whistler-mode emission at frequencies just below fce (5.5 kHz). These emissions could be locally generated by resonant wave-particle interactions involving an electron beam of ~100 eV energy. A second type is a low frequency (200--300 Hz) whistler mode wave, which may be locally generated by ~25 keV electrons or ~45 keV ions. It is also possible that these latter waves are generated at low altitudes near the ionosphere and then converted from the ion cyclotron mode into whistler-mode during propagation from the generation region to the spacecraft. Two further types of waves are large-amplitude bipolar and monopolar solitary electrostatic waves. The bipolar wave structures are possibly generated all along the magnetic field lines in the field-aligned current regions (at all local times). The monopolar structures could be evolved bipolar solitary waves. A one-d schematic is presented to explain the paired monopolar structures as a result of splitting of an electron hole into two parts. ¿ 1998 American Geophysical Union