Reference signal configuration for extension carriers and carrier segments

Reference signals configured for use with extension carriers and/or carrier segments are described. Reference signals for extension carriers and/or carrier segments may include demodulation reference signals (e.g., user equipment-specific reference signals), cell-specific reference signals, and channel-state information reference signals. Methods, systems and apparatuses for configuring extension carriers and/or carrier segments with one or more of the reference signals (e.g., positioning one or more reference signal symbols in extension carriers and/or carrier segments) are described.