Reference signaling for radio access networks
There is disclosed a method of operating a signaling radio node in a radio access network, the signaling radio node being adapted for transmitting on a plurality of layers utilizing an antenna arrangement; wherein the method comprises transmitting, on each of the plurality of layers, reference signaling in the same symbol time interval, wherein reference signaling on at least a first layer of the plurality of layers is shifted in time and/or phase relative to reference signaling on at least a second layer of the plurality of layers. There are also disclosed related methods and devices.
1. A method of operating a signaling radio node in a radio access network, the signaling radio node being adapted for transmitting on a plurality of layers utilizing an antenna arrangement; wherein the method comprises transmitting, on each of the plurality of layers, reference signaling in the same symbol time interval, wherein reference signaling on at least a first layer of the plurality of layers is shifted in time and/or phase relative to reference signaling on at least a second layer of the plurality of layers, wherein the shift corresponds to a shift in time domain smaller than a cyclic prefix associated to transmission on the layer, and wherein each layer is associated with a different reference signaling port of a plurality of reference signaling ports, and the reference signaling ports are mapped to subcarriers according to different sequences, mapping the reference signaling ports to the subcarriers comprising a type 1 mapping and a type 2 mapping, the type 1 mapping comprising a comb structure and wherein the type 1 mapping comprises a denser pattern in a frequency-domain than the type 2 mapping.
2. A method according to claim 1 , wherein transmission on different layers shares antenna elements of the antenna arrangement.
3. A method according to claim 1 , wherein for each layer, the reference signaling is mapped in frequency domain to subcarriers according to one of the different sequences.
4. A method according to claim 1 , wherein the reference signaling is a demodulation reference signal and the demodulation reference signal is shifted by applying a phase shift to elements of a sequence associated to a layer.
5. A method according to claim 1 , wherein reference signaling on the at least first layer is based on the same sequence as reference signaling of the at least second layer.
6. A method according to claim 1 , wherein a layer corresponds to a transmission beam.
7. A method according to claim 1 , wherein a receiving radio node is configured with a shift indication by the signaling radio node.
8. The method of claim 7 , wherein the signaling radio node is configured to transmit the shift indication with control signaling to the receiving radio node.
9. A method according to claim 1 , wherein the reference signaling is shifted before precoding is performed for transmission.
10. A method according to claim 1 , wherein the reference signaling is shifted after mapping of reference signaling to resource elements.
11. A non-transitory storage medium comprising instructions adapted for causing processing circuitry to control and/or perform a method according to claim 1 .
12. The method of claim 1 , wherein the shift is about 10% or less than the cyclic prefix associated to the transmission on the layer.
13. The method of claim 1 , wherein the plurality of layers is grouped into Code Division Multiplex (CDM) groups using Orthogonal Cover Codes (OCC).
14. A signaling radio node for a radio access network, the signaling radio node being adapted for transmitting a plurality of layers utilizing an antenna arrangement; the signaling radio node further being adapted for transmitting, on each of the plurality of layers, reference signaling in the same symbol time interval, wherein reference signaling on at least a first layer of the plurality of layers is shifted in time and/or phase relative to reference signaling on at least a second layer of the plurality of layers, wherein the shift corresponds to a shift in time domain smaller than a cyclic prefix associated to transmission on the layer, and wherein each layer is associated with a different reference signaling port of a plurality of reference signaling ports, and the reference signaling ports are mapped to subcarriers according to different sequences, mapping the reference signaling ports to the subcarriers comprising a type 1 mapping and a type 2 mapping, the type 1 mapping comprising a comb structure and wherein the type 1 mapping comprises a denser pattern in a frequency-domain than the type 2 mapping.
15. A signaling radio node according to claim 14 , wherein transmission on different layers shares antenna elements of the antenna arrangement.
16. A signaling radio node according to claim 14 , wherein for each layer, the reference signaling is mapped in frequency domain to subcarriers according to one of the different sequences.
17. A signaling radio node according to claim 14 , wherein the reference signaling is a demodulation reference signal and the demodulation reference signal is shifted by applying a phase shift to elements of a sequence associated to a layer.
18. A signaling radio node according to claim 14 , wherein reference signaling on the at least first layer is based on the same sequence as reference signaling of the at least second layer.