Processing reference signal across multiple signal carriers

1 . An apparatus comprising:

at least one processor; and

at least one memory configured to store instructions that when executed by the at least one processor, cause the apparatus at least to:

obtain aggregated reference signals received from multiple signal carriers over channels of a mobile communication system, wherein the multiple signal carriers have different carrier frequencies;

initialize a first matrix, a channel power matrix and a noise estimate, wherein the first matrix models how a carrier frequency offset (CFO) of a channel of the channels rotates a reference signal phase;

sequentially update:

a channel impulse response (CIR) estimate, the channel power matrix and the noise estimate;

a second matrix, wherein the second matrix describes how reference signals transmitted over the channel are spread and delayed due to multipath propagation;

a vector of channel frequency offset; and

the first matrix; and

repeat the sequential update until a termination condition is reached.

2 . The apparatus of claim 1 , wherein the apparatus is further caused to generate a position estimate based on at least one of the CIR estimate and the CFO.

3 . The apparatus of claim 1 , wherein the apparatus is caused to sequentially update the CIR estimate based on a theory that the CIR estimate is sparse or has a constant delay profile across carriers.

4 . The apparatus of claim 1 , wherein the second matrix is updated based, at least in part, on the updated CIR estimate.

5 . The apparatus of claim 1 , wherein the vector of channel frequency offset is updated based, at least in part, on power and noise estimates, and on the updated second matrix.

6 . The apparatus of claim 1 , wherein the first matrix is updated based, at least in part, on the updated vector of channel frequency offset.

7 . The apparatus of claim 1 , wherein the updated first matrix is utilized in updating of the CIR estimate on a next iteration of the sequential update.

8 . The apparatus of claim 1 , wherein the aggregated reference signals are caused the apparatus to receive the reference signals transmitted on carriers over the channel of the mobile communication system, and aggregate the received reference signals.

9 . The apparatus of claim 1 , wherein the multiple signal carriers comprise intra-band carriers.

10 . The apparatus of claim 1 , wherein the multiple signal carriers comprise inter-band carriers.

11 . The apparatus of claim 10 , wherein the apparatus is caused to update the CFO based on a theory that the CFO estimates across carriers are independent.

12 . The apparatus of claim 1 , wherein the multiple signal carriers have contiguous frequencies.

13 . The apparatus of claim 1 , wherein the reference signals comprise position reference signals, sounding reference signals, or synchronization signals.

14 . A method comprising:

obtaining aggregated reference signals received from multiple signal carriers over channels of a mobile communication system, wherein the multiple signal carriers have different carrier frequencies;

initializing a first matrix, a channel power matrix and a noise estimate, wherein the first matrix models how a carrier frequency offset (CFO) of a channel of the channels rotates a reference signal phase;

sequentially updating:

a channel impulse response (CIR) estimate, the channel power matrix and the noise estimate;

a second matrix, wherein the second matrix describes how reference signals transmitted over the channel are spread and delayed due to multipath propagation;

a vector of channel frequency offset; and

the first matrix; and

repeating the sequential updating until a termination condition is reached.

15 . The method of claim 14 , further comprising:

generating a position estimate based on at least one of the CIR estimate and the CFO.

16 . The method of claim 14 , wherein the sequentially updating the CIR estimate is based on a theory that the CIR estimate is sparse or has a constant delay profile across carriers.

17 . The method of claim 14 , wherein the second matrix is updated based, at least in part, on the updated CIR estimate.

18 . The method of claim 14 , wherein the vector of channel frequency offset is updated based, at least in part, on power and noise estimates, and on the updated second matrix.

19 . The method of claim 14 , wherein the first matrix is updated based, at least in part, on the updated vector of channel frequency offset.

20 . The method of claim 14 , wherein the updated first matrix is utilized in updating of the CIR estimate on a next iteration of the sequential updating.