The name "UE Specific" and "Cell specific" is the first clue.
Release 8 of LTE had cell specific reference signals.These reference signals are used for both demodulation and channel estimation. the location of the cell specific signals is known and is constant to all the UEs in that cell and hence can be used for demodulation of PDSCH. The location of the C-RS depends on the Physical Cell ID, the number of antennas. Also the C-RS is used for channel estimation based on PDSCH power control. The reference power is specified in the system information and it is used for Channel estimation.
However in Release 10, they changed the design slightly. They have separate signals for Demodulation and Channel Estimation. Note that these signals are used by the Release 10 UEs ALONGWITH the C-RS. DM-RS is configured using DMRS-Config-r11. For the location of the DM-RS Config depends on which port on which the DM-RS is being transmitted (=which in turn depends on what is the transmission mode of the UE). See here for the examples of the location of DM-RS :
http://www.sharetechnote.com/html/FrameStructure_DL.html#RS_UE_Specific
