Initialization of reference signal scrambling
View Patent ↗A scrambling sequence is initialized using at least a cell identifier and an offset, and a physical downlink control information DCI is sent to a user equipment which indicates the offset. In more particular embodiments a user equipment-specific reference signal UE-RS is scrambled using the initialized scrambling sequence, and the scrambled UE-RS is sent to the UE for demodulating a downlink shared channel (PDSCH). In another exemplary embodiment the generated UE-RS is sent in a pilot part of a subframe transmission associated with the PDSCH and is for demodulating at least a data part of that subframe transmission. In a specific embodiment from the UE side, the UE receives the UE-RS and the DCI which indicates the offset, descrambles the UE-RS using a scrambling sequence that is initialized using a cell identifier and the indicated offset; and demodulates the PDSCH using the de-scrambled UE-RS.
1. A method comprising:
initializing a scrambling sequence using a cell identifier and a non-fixed offset; and
sending a physical downlink control information to a user equipment which indicates the offset.
2. The method according to claim 1 , further comprising sending a user equipment specific reference signal to the user equipment for demodulating a downlink shared channel, wherein the user equipment specific reference signal is scrambled by the scrambling sequence.
3. The method according to claim 1 , wherein the physical downlink control information is transmitted on a physical downlink shared control channel (PDCCH).
4. An apparatus comprising:
at least one processor; and
at least one memory storing computer program code configured to, with the at least one processor, cause the apparatus at least to perform:
initializing a scrambling sequence using a cell identifier and a non-fixed offset; and
sending a physical downlink control information to a user equipment which indicates the offset.
5. The apparatus according to claim 4 , wherein the memory storing computer program code is configured with the at least one processor to cause the apparatus at least to further perform: sending a user equipment specific reference signal to the user equipment for demodulating a downlink shared channel, wherein the user equipment specific reference signal is scrambled by the scrambling sequence.
6. The apparatus according to claim 4 , wherein the offset corresponds to a single specific scrambling sequence.
7. The apparatus according to claim 4 , wherein the physical downlink control information is transmitted on a physical downlink shared control channel (PDCCH).
8. The apparatus according to claim 4 , wherein the cell identifier is selected from a set of coordinated multipoint transmission cell identifiers.
9. The apparatus according to claim 5 , wherein the user equipment specific reference signal is sent to the user equipment in a pilot part of a subframe transmission associated with the physical downlink shared channel, and the user equipment specific reference signal is for demodulating at least a data part of the transmission associated with the physical downlink shared channel.
10. A memory storing computer program code that when executed by at least one processor result in operations comprising:
initializing a scrambling sequence using a cell identifier and a non-fixed offset; and
sending a physical downlink control information to a user equipment which indicates the offset.
11. The memory according to claim 10 , the operations further comprising: sending a user equipment specific reference signal to the user equipment for demodulating a downlink shared channel, wherein the user equipment specific reference signal is scrambled by the scrambling sequence.
12. A method comprising:
receiving a physical downlink control information which indicates a non-fixed offset; and
initializing a scrambling sequence using a cell identifier and the offset.
13. The method according to claim 12 , further comprising receiving a user equipment specific reference signal for demodulating a downlink shared channel, wherein the user equipment specific reference signal is scrambled by the scrambling sequence.
14. The method according to claim 12 , in which the physical downlink control information is received on a physical downlink shared control channel (PDCCH).
15. An apparatus comprising:
at least one processor; and
at least one memory storing computer program code configured to, with the at least one processor, cause the apparatus at least to perform:
receiving a physical downlink control information which indicates a non-fixed offset; and
initializing a scrambling sequence using a cell identifier and the offset.
16. The apparatus according to claim 15 , wherein the memory storing computer program code is configured with the at least one processor to cause the apparatus at least to further perform: receiving a user equipment specific reference signal for demodulating a downlink shared channel, wherein the user equipment specific reference signal is scrambled by the scrambling sequence.
17. The apparatus according to claim 15 , wherein the offset corresponds to a single specific scrambling sequence.
18. The apparatus according to claim 15 , wherein the physical downlink control information is received on a physical downlink shared control channel (PDCCH).
19. The apparatus according to claim 15 , wherein the cell identifier comprises an identifier for one cell in a wireless network from which the downlink control information was received, and wherein the apparatus comprises a user equipment associated with a user specific reference signal that is scrambled by the scrambling sequence.
20. A memory storing computer program code that when executed by at least one processor result in operations comprising:
receiving downlink control information which indicates a non-fixed offset; and
initializing a scrambling sequence using a cell identifier and the offset.
21. The method according to claim 20 , further comprising receiving a user equipment specific reference signal for demodulating a downlink shared channel, wherein the user equipment specific reference signal is scrambled by the scrambling sequence.