Methods of performing communications, mobile terminal devices, and baseband modems

1. A mobile terminal device having a radio processing circuit and a baseband processing circuit adapted to interact with the radio processing circuit, the mobile terminal device configured to:

identify a first set of frequency resources allocated for a wireless channel by a mobile communication network;

calculate a first channel response estimate for a second set of frequency resources of the wireless channel using a reference signal derived from a second mobile terminal device, wherein the reference signal is distributed across the second set of frequency resources of the wireless channel;

calculate a channel impulse response estimate for the wireless channel based on the first channel frequency response estimate;

calculate a second channel response estimate for the first set of frequency resources of the wireless channel based on the channel impulse response estimate; and

apply the second channel response estimate to schedule data transmission intended for the second mobile terminal device over the wireless channel.

2. The mobile terminal device of claim 1 , wherein the first set of frequency resources has a greater bandwidth of the wireless channel than the second set of frequency resources.

3. The mobile terminal device of claim 1 , wherein applying the second channel response estimate to schedule data transmission intended for the second terminal device over the wireless channel comprises:

performing one of frequency resource selection, modulation scheme selection, or coding rate selection based on the second channel response estimate.

4. The mobile terminal device of claim 1 , wherein applying the second channel response estimate to schedule data transmission intended for the second mobile terminal device over the wireless channel comprises:

selecting a third set of frequency resources of the wireless channel using the second channel response estimate; and

transmitting data intended for the second mobile terminal device over the wireless channel using the third set of frequency resources.

5. The mobile terminal device of claim 4 , wherein selecting the third set of frequency resources of the wireless channel using the second channel response estimate comprises:

identifying one or more frequency resources of the first set of frequency resources of the wireless channel that have strong channel conditions according to the second channel response estimate; and

selecting the one or more frequency resources as the third set of frequency resources.

6. The mobile terminal device of claim 5 , wherein the third set of frequency resources are a subset of the first set of frequency resources.

7. The mobile terminal device of claim 1 , wherein calculating the channel impulse response estimate for the wireless channel using the first channel response estimate comprises:

applying at least one of least squares (LS) estimation, minimum mean square error (MMSE) estimation (MMSE), or linear minimum mean square error (LMMSE) estimation to the first channel response estimate to calculate the channel response estimate.

8. The mobile terminal device of claim 1 , wherein the reference signal is a Primary Sidelink Synchronization Signal (PSSS) or a Secondary Sidelink Synchronization Signal (SSSS).

9. The mobile terminal device of claim 1 , wherein the first set of frequency resources comprise a first set of subcarriers and the second set of frequency resources comprise a second set of subcarriers.

10. The mobile terminal device of claim 1 , further configured to receive the reference signal from the second mobile terminal device on the second set of frequency resources of the wireless channel, wherein the second set of frequency resources is a subset of the first set of frequency resources.

11. The mobile terminal device of claim 1 , wherein the wireless channel is a device-to-device wireless channel.

12. A method of performing communications, the method comprising:

identifying a first set of frequency resources allocated for a wireless channel by a mobile communication network;

calculating a first channel response estimate for a second set of frequency resources of the wireless channel using a reference signal derived from a terminal device, wherein the reference signal is distributed across the second set of frequency resources of the wireless channel;

calculating a channel impulse response estimate for the wireless channel based on the first channel frequency response estimate;

calculating a second channel response estimate for the first set of frequency resources of the wireless channel based on the channel impulse response estimate; and

applying the second channel response estimate to schedule data transmission intended for the terminal device over the wireless channel.

13. The method of claim 12 , wherein the first set of frequency resources has a greater bandwidth of the wireless channel than the second set of frequency resources.

14. The method of claim 12 , wherein applying the second channel response estimate to schedule data transmission intended for the terminal device over the wireless channel further comprises:

performing one of frequency resource selection, modulation scheme selection, or coding rate selection based on the second channel response estimate.

15. The method of claim 12 , wherein the first set of frequency resources is a set of subcarriers allocated by the mobile communication network for Proximity Services (ProSe).

16. The method of claim 12 , wherein applying the second channel response estimate to schedule data transmission intended for the terminal device over the wireless channel further comprises:

selecting a third set of frequency resources of the wireless channel using the second channel response estimate; and

transmitting data intended for the terminal device over the wireless channel using the third set of frequency resources.

17. The method of claim 12 , wherein calculating the second channel response estimate for the first set of frequency resources of the wireless channel using the first channel response estimate further comprises:

calculating a channel impulse response estimate for the wireless channel using the first channel response estimate; and

calculating the second channel response estimate as a channel frequency response estimate of the wireless channel over the first set of frequency resources using the channel impulse response estimate.

18. The method of claim 17 , wherein the first channel response estimate approximates the channel frequency response of the wireless channel over the second set of frequency resources and the second channel response estimate approximates the channel frequency response of the wireless channel over the first set of frequency resources.

19. The method of claim 17 , wherein calculating the channel impulse response estimate for the wireless channel using the first channel response estimate comprises:

applying at least one of least squares (LS) estimation, minimum mean square error (MMSE) estimation (MMSE), or linear minimum mean square error (LMMSE) estimation to the first channel response estimate to calculate the channel response estimate.

20. The method of claim 12 , wherein the reference signal is a Primary Sidelink Synchronization Signal (PSSS) or a Secondary Sidelink Synchronization Signal (SSSS).

21. The method of claim 12 , further comprising receiving the reference signal from the terminal device on the second set of frequency resources of the wireless channel, wherein the second set of frequency resources is a subset of the first set of frequency resources.

22. The method of claim 12 , wherein the wireless channel is a device-to-device wireless channel.

23. A mobile terminal device having a radio processing circuit and a baseband processing circuit adapted to interact with the radio processing circuit, the mobile terminal device configured to:

identify a first set of frequency resources allocated for a wireless channel by a mobile communication network;

calculate a first channel response estimate for a second set of frequency resources of the wireless channel using a reference signal derived from a second mobile terminal device, wherein the reference signal is distributed across the second set of frequency resources of the wireless channel;

calculate a second channel response estimate for the first set of frequency resources of the wireless channel using the first channel response estimate, wherein calculating the second channel response estimate for the first set of frequency resources of the wireless channel using the first channel response estimate comprises calculating a channel impulse response estimate for the wireless channel using the first channel frequency response estimate, and calculating the second channel frequency response estimate using the channel impulse response estimate; and

apply the second channel response estimate to schedule data transmission intended for the second mobile terminal device over the wireless channel,

wherein the first channel response estimate is a first channel frequency response estimate approximating the frequency response of the wireless channel over the second set of frequency resources and the second channel response estimate is a second channel frequency response estimate approximating the frequency response of the wireless channel over the first set of frequency resources.