A mobile terminal apparatus, comprising: one or more processing elements configured to couple to a wireless radio (36, 38); and one or more memories having program instructions stored thereon that when executed by the one or more processing elements cause the apparatus to: receive a first time difference of arrival reference signal, TDOA-RS, from a first base station serving the apparatus via a first cell and a second TDOA-RS via a second cell over a radio access network; receive a cell specific reference signal via the first cell, wherein the cell specific reference signal is different from the first TDOA-RS; determine a time difference of arrival between the first TDOA-RS received from the first base station serving the apparatus via the first cell and the second TDOA-RS received via the second cell over the radio access network; report the determined time difference to the first base station; wherein the first TDOA-RS is received using one or more first resource elements in one or more resource blocks; wherein a resource element corresponds to one subcarrier in one orthogonal frequency-division multiplexing, OFDM, symbol, wherein a resource block consists of a plurality of resource elements occupying a contiguous set of subcarrier frequencies across a plurality of OFDM symbols, and wherein resource elements used for TDOA-RS are based at least in part on respective cell identifiers of transmitting cells; wherein the one or more first resource elements in the one or more resource blocks used for the first TDOA-RS correspond to a first transmission instance of a plurality of transmission instances from the first cell; and characterized in that the apparatus is caused to receive plurality of transmission instances in two or more different sets of a plurality of sets of one or more resource blocks according to a frequency hopping pattern. receive a first time difference of arrival reference signal, TDOA-RS, from a first base station serving the apparatus via a first cell and a second TDOA-RS via a second cell over a radio access network; receive a cell specific reference signal via the first cell, wherein the cell specific reference signal is different from the first TDOA-RS; determine a time difference of arrival between the first TDOA-RS received from the first base station serving the apparatus via the first cell and the second TDOA-RS received via the second cell over the radio access network; report the determined time difference to the first base station; wherein the first TDOA-RS is received using one or more first resource elements in one or more resource blocks; wherein a resource element corresponds to one subcarrier in one orthogonal frequency-division multiplexing, OFDM, symbol, wherein a resource block consists of a plurality of resource elements occupying a contiguous set of subcarrier frequencies across a plurality of OFDM symbols, and wherein resource elements used for TDOA-RS are based at least in part on respective cell identifiers of transmitting cells; wherein the one or more first resource elements in the one or more resource blocks used for the first TDOA-RS correspond to a first transmission instance of a plurality of transmission instances from the first cell; and characterized in that the apparatus is caused to receive plurality of transmission instances in two or more different sets of a plurality of sets of one or more resource blocks according to a frequency hopping pattern.