Methods and apparatuses for providing transmit/receive relative radio alignment verification
Radio alignment of downlink and uplink channels between a wireless device and a multi-antenna base station. A method performed by a network node comprises obtaining downlink channel data, wherein the downlink channel data comprises: estimates of a plurality of downlink channels each associated with a downlink reference signal being received from one of the antennas at the wireless device, and time synchronization information associated with each of the downlink channels; obtaining uplink channel data, wherein the uplink channel data comprises: estimates of a plurality of uplink channels each associated with an uplink reference signal being received at one of the antennas from the wireless device, and time synchronization information associated with each of the uplink channels; comparing the downlink channel data and the uplink channel data to determine whether the downlink channel and uplink channel between the wireless device and the multi-antenna base station are aligned.
1. A method performed by a network node for determining radio alignment of a full downlink channel and a full uplink channel between a wireless device and a multi-antenna base station comprising a plurality of antennas, the method comprising:
obtaining downlink channel data, wherein the downlink channel data comprises:
estimates of a plurality of downlink channels each associated with a downlink reference signal being received from one of the plurality of antennas at the wireless device, and time synchronization information associated with each of the plurality of downlink channels,
wherein the estimates of the plurality of downlink channels comprises estimates of a plurality of subset vector channels each associated with a different time instance, m i , and estimates of a phase tracking channel at each different time instance, m i , and
wherein the phase tracking channel is associated with a first downlink reference signal always transmitted from a first antenna of the plurality of antennas, and the plurality of subset vector channels is associated with a plurality of cycled downlink reference signals cycled over the plurality of antennas excluding the first antenna over consecutive downlink slots, the plurality of cycled downlink reference signals being fewer than the plurality of antennas excluding the first antenna;
obtaining uplink channel data, wherein the uplink channel data comprises:
estimates of a plurality of uplink channels each associated with an uplink reference signal being received one of the plurality of antennas from the wireless device, and time synchronization information associated with each of the plurality of uplink channels; and
comparing the downlink channel data and the uplink channel data to determine whether the downlink channel and uplink channel between the wireless device and the multi-antenna base station are aligned.
2. The method as claimed in claim 1 further comprising:
selecting a first time instance, m 1 ;
for each of the plurality of subset vector channels associated with time instance m i
determining a phase difference between the phase tracking channel at m i and the phase tracking channel at m 1 ; and
de-rotating the subset vector channel by the phase difference to provide an estimate of the subset vector channel at time instance m i ; and
stacking the estimates of the plurality of subset vector channels at time instance m i on top of the estimate of the phase tracking channel at time instance m i to determine an estimate of a full downlink vector channel at time instance m 2 .
3. The method as claimed in claim 2 wherein the estimates of the plurality of uplink channels comprises an estimate of a full uplink vector channel at different time instances, m k , wherein the step of comparing the downlink channel data and the uplink channel data comprises:
comparing the estimate of the full downlink vector channel at time instance m 2 with the estimate of the full uplink vector channel at time instance m 2 .
4. The method as claimed in claim 1 , wherein the method is performed by the wireless device.
5. The method as claimed in claim 1 , wherein the method is performed by the multi-antenna base station.
6. A method performed by a wireless device in communication with a multi-antenna base station comprising a plurality of antennas for radio alignment of downlink channels and uplink channels between the wireless device and the multi-antenna base station, the method comprising:
transmitting uplink reference signals from an antenna in the wireless device to the multi-antenna base station, wherein the uplink reference signals are transmitted across multiple time instances;
receiving downlink reference signals from the multi-antenna base station wherein the downlink reference signals are received over multiple time instances; and
determining downlink channel data, wherein the downlink channel data comprises:
estimates of a plurality of downlink channels associated with each of the downlink reference signals, and time synchronization information associated with each of the plurality of downlink channels,
wherein the estimates of the plurality of downlink channels comprises estimates of a plurality of subset vector channels each associated with a different time instance and estimates of a phase tracking channel at each different time instance, and
wherein the phase tracking channel is associated with a first downlink reference signal always transmitted from a first antenna of the plurality of antennas, and the plurality of subset vector channels is associated with a plurality of cycled downlink reference signals cycled over the plurality of antennas excluding the first antenna over consecutive downlink slots, the plurality of cycled downlink reference signals being fewer than the plurality of antennas excluding the first antenna.
7. The method as claimed in claim 6 further comprising obtaining the time synchronization information by time stamping each of the plurality of downlink channels upon reception of the respective downlink reference signals.
8. The method as claimed in claim 6 further comprising obtaining the time synchronisation information by receiving a time stamp associated with each of the downlink reference signals.
9. The method of claim 6 further comprising transmitting the downlink channel data to the multi-antenna base station.
10. The method of claim 6 further comprising transmitting the downlink channel data to a network node.
11. A wireless device in communication with a multi-antenna base station comprising a plurality of antennas for radio alignment of downlink channels and uplink channels between the wireless device and the multi-antenna base station, the wireless device comprising processing circuitry to:
transmit uplink reference signals from an antenna in the wireless device to the multi-antenna base station, wherein the uplink reference signals are transmitted across multiple time instances;
receive downlink reference signals from the multi-antenna base station wherein the downlink reference signals are received over multiple time instances; and
determine downlink channel data, wherein the downlink channel data comprises:
estimates of a plurality of downlink channels associated with each of the downlink reference signals, and time synchronization information associated with each of the plurality of downlink channels,
wherein the estimates of the plurality of downlink channels comprises estimates of a plurality of subset vector channels each associated with a different time instance and estimates of a phase tracking channel at each different time instance, and
wherein the phase tracking channel is associated with a first downlink reference signal always transmitted from a first antenna of the plurality of antennas, and the plurality of subset vector channels is associated with a plurality of cycled downlink reference signals cycled over the plurality of antennas excluding the first antenna over consecutive downlink slots, the plurality of cycled downlink reference signals being fewer than the plurality of antennas excluding the first antenna.
12. A network node for determining radio alignment of a full downlink channel and a full uplink channel between a wireless device and a multi-antenna base station comprising a plurality of antennas, the network node comprising processing circuitry to:
obtain downlink channel data, wherein the downlink channel data comprises:
estimates of a plurality of downlink channels each associated with a downlink reference signal being received from one of the plurality of antennas at the wireless device, and time synchronization information associated with each of the plurality of downlink channels,
wherein the estimates of the plurality of downlink channels comprises estimates of a plurality of subset vector channels each associated with a different time instance, m i , and estimates of a phase tracking channel at each different time instance, m i , and
wherein the phase tracking channel is associated with a first downlink reference signal always transmitted from a first antenna of the plurality of antennas, and the plurality of subset vector channels is associated with a plurality of cycled downlink reference signals cycled over the plurality of antennas excluding the first antenna over consecutive downlink slots, the plurality of cycled downlink reference signals being fewer than the plurality of antennas excluding the first antenna;
obtain uplink channel data, wherein the uplink channel data comprises:
estimates of a plurality of uplink channels each associated with an uplink reference signal being received one of the plurality of antennas from the wireless device, and time synchronization information associated with each of the plurality of uplink channels; and
compare the downlink channel data and the uplink channel data to determine whether the downlink channel and uplink channel between the wireless device and the multi-antenna base station are aligned.
13. The wireless device as claimed in claim 11 further to obtain the time synchronization information by time stamping each of the plurality of downlink channels upon reception of the respective downlink reference signals.
14. The wireless device as claimed in claim 11 further to obtain the time synchronisation information by receiving a time stamp associated with each of the downlink reference signals.
15. The network node as claimed in claim 12 further comprising:
select a first time instance, m 1 ;
for each of the plurality of subset vector channels associated with time instance m i
determine a phase difference between the phase tracking channel at m i and the phase tracking channel at m 1 ; and
de-rotate the subset vector channel by the phase difference to provide an estimate of the subset vector channel at time instance m i ; and
stack the estimates of the plurality of subset vector channels at time instance m i on top of the estimate of the phase tracking channel at time instance m i to determine an estimate of a full downlink vector channel at time instance m 2 .
16. The network node as claimed in claim 15 , wherein the estimates of the plurality of uplink channels comprises an estimate of a full uplink vector channel at different time instances, m k , wherein when comparing the downlink channel data and the uplink channel data comprises:
compare the estimate of the full downlink vector channel at time instance m 2 with the estimate of the full uplink vector channel at time instance m 2 .