QUASI CO-LOCATED ANTENNA PORTS FOR CHANNEL ESTIMATION

• US 20140036800A1
• Filed: 06/14/2013
• Published: 02/06/2014
• Est. Priority Date: 08/03/2012
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Frenne, Mattias, Eriksson, Erik, Sorrentino, Stefano
• Granted Patent: US 9,203,576 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0091 Signaling for the administration of the divided path
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 84/042 Public Land Mobile systems, e.g. cellular systems

Abstract

Systems and methods are disclosed for estimating one or more channel properties of a downlink from a cellular communications network based on quasi co-located antenna ports with respect to the one or more channel properties. In one embodiment, a wireless device receives a downlink subframe including a downlink control channel from the cellular communications network. The wireless device estimates one or more large-scale channel properties for an antenna port of interest in the downlink control channel based on a subset of reference signals that correspond to antenna ports in the cellular communications network that are quasi co-located with the antenna port of interest with respect to the one or more large-scale channel properties. As a result of using the quasi co-located antenna ports, estimation of the one or more large-scale channel properties is substantially improved.

Claims

1. A wireless device configured to operate in a cellular communications network, comprising:

a radio subsystem; and

a processing subsystem associated with the radio subsystem configured to;

receive, via the radio subsystem, a downlink subframe comprising a downlink control channel from the cellular communications network; and

estimate one or more large-scale channel properties for an antenna port of interest in the downlink control channel based on a subset of a plurality of reference signals corresponding to antenna ports in the cellular communications network that are quasi co-located with the antenna port of interest with respect to the one or more large-scale channel properties.

2. The wireless device of claim 1 wherein the subset of the plurality of reference signals comprise:

reference signals that are transmitted in different reference signal ports for the same reference signal type in the same physical resource block within the downlink subframe;

wherein the different reference signal ports for the same reference signal type in the same physical resource block within the downlink subframe correspond to antenna ports that are quasi co-located with respect to the one or more large-scale channel properties.

3. The wireless device of claim 1 wherein the subset of the plurality of reference signals comprise reference signals that are:

the same reference signal transmitted in the same reference signal port for the same reference signal type in a different physical resource block within the downlink subframe;

wherein the reference signal port for the same reference signal type in the different physical resource block within the downlink subframe correspond to antenna ports that are quasi co-located with respect to the one or more large-scale channel properties.

4. The wireless device of claim 1 wherein the subset of the plurality of reference signals comprise:

reference signals that are transmitted in different reference signal ports for different reference signal types in the same physical resource block within the downlink subframe;

wherein the different reference signal ports for the different reference signal types in the same physical resource block within the downlink subframe correspond to antenna ports that are quasi co-located with respect to the one or more large-scale channel properties.

5. The wireless device of claim 1 wherein the subset of the plurality of reference signals comprise:

reference signals that are transmitted in different reference signal ports for different reference signal types in different physical resource blocks within the downlink subframe;

wherein the different reference signal ports for the different reference signal types in the different physical resource blocks within the downlink subframe correspond to antenna ports that are quasi co-located with respect to the one or more large-scale channel properties.

6. The wireless device of claim 1 wherein the processing subsystem is further configured to receive, via the radio subsystem, information from the cellular communications network that is indicative of the antenna ports that are quasi co-located with the antenna port of interest with respect to the one or more large-scale channel properties.

7. The wireless device of claim 6 wherein the information from the cellular communications network is further indicative of one or more physical resource blocks over which the antenna ports are quasi co-located with the antenna port of interest with respect to the one or more large-scale channel properties.

8. The wireless device of claim 1 wherein the antenna ports that are quasi co-located with the antenna port of interest with respect to the one or more large-scale channel properties are predefined for the cellular communications network.

9. The wireless device of claim 8 wherein one or more physical resource blocks over which the antenna ports are quasi co-located with the antenna port of interest with respect to the one or more large-scale channel properties are also predefined by the cellular communications network.

10. The wireless device of claim 1 wherein the antenna ports that are quasi co-located with the antenna port of interest with respect to the one or more large-scale channel properties comprise first antenna ports that are predefined for the cellular communications network as being quasi co-located with the antenna port of interest with respect to the one or more large-scale channel properties and second antenna ports indicated as being quasi co-located with the antenna port of interest with respect to the one or more large-scale channel properties via signaling from the cellular communications network.

11. The wireless device of claim 10 wherein one or more physical resource blocks over which the first antenna ports are quasi co-located with the antenna port of interest with respect to the one or more large-scale channel properties are also predefined by the cellular communications network.

12. The wireless device of claim 10 wherein one or more physical resource blocks over which the second antenna ports are quasi co-located with the antenna ort of interest with respect to the one or more large-scale channel properties are also indicated to the wireless device via signaling from the cellular communications network.

13. The wireless device of claim 1 wherein the cellular communications network is a Long Term Evolution cellular communications network, and the downlink control channel is an enhanced Physical Downlink Control Channel.

14. The wireless device of claim 1 wherein:

the wireless device does not assume that antenna ports that correspond to reference signals in an enhanced Physical Downlink Control Channel are quasi co-located with respect to large-scale channel properties between antenna ports and between physical resource blocks within a subframe; and

the antenna ports that are quasi co-located with the antenna port of interest with respect to the one or more large-scale channel properties comprise antenna ports signaled by the cellular communications network.

15. The wireless device of claim 1 wherein:

the cellular communications network is a Long Term Evolution cellular communications network;

the downlink control channel is an enhanced Physical Downlink Control Channel; and

the plurality of reference signals comprise a plurality of reference signals transmitted within the enhanced Physical Downlink Control Channel.

16. The wireless device of claim 15 wherein:

the wireless device does not assume that any antenna ports corresponding to Demodulation Reference Signal ports within the enhanced Physical Downlink Control Channel are quasi co-located with respect to long-term channel properties between antenna ports and between physical resource blocks within the downlink subframe; and

the processing subsystem is further configured to;

determine whether a downlink control information message transmitted in the enhanced Physical Downlink Control Channel is associated with two or more Demodulation Reference Signal ports;

wherein, if the downlink control information message is associated with two or more Demodulation Reference Signal ports, the antenna ports that are quasi co-located with respect to the one or more large-scale channel properties comprise antenna ports associated with the downlink control information message for physical resource blocks associated with the downlink control information message.

17. The wireless device of claim 15 wherein:

the wireless device does not assume that any antenna ports corresponding to Demodulation Reference Signal ports within the enhanced Physical Downlink Control Channel are quasi co-located with respect to long-term channel properties between antenna ports and between physical resource blocks within the downlink subframe; and

the processing subsystem is further configured to;

determine whether a downlink control information message transmitted on the enhanced Physical Downlink Channel is associated with two or more physical resource blocks;

wherein if the downlink control information message is associated with two or more physical resource blocks, the antenna ports that are quasi co-located with respect to the one or more large-scale channel properties comprise antenna ports associated with the downlink control information message for physical resource blocks associated with the downlink control information message.

18. The wireless device of claim 15 wherein a search space of the wireless device with respect to the enhanced Public Downlink Control Channel includes two or more sets of physical resources, and the antenna ports that are quasi co-located with respect to the one or more large-scale channel properties comprise antenna ports within the same set of the two or more sets of physical resources.

19. The wireless device of claim 15 wherein a search space of the wireless device with respect to the enhanced Public Downlink Control Channel includes two or more sets of physical resources, and the processing subsystem is further configured to:

receive information from the cellular communications network that is indicative of which antenna ports within the two or more sets of physical resources are quasi co-located with respect to the one or more large-scale channel properties.

20. The wireless device of claim 19 wherein the information from the cellular communications network indicates that the antenna ports within the same set of physical resources are quasi co-located with respect to the one or more large-scale channel properties, and the antenna ports that are quasi co-located and on which the estimate of the one or more large-scale channel properties is based comprise the antenna ports in the same set of physical resources.

21. The wireless device of claim 19 wherein the information from the cellular communications network indicates that the antenna ports within two or more different sets of physical resources from the two or more sets of physical resources are quasi co-located with respect to the one or more large-scale channel properties, and the antenna ports that are quasi co-located and on which the estimate of the one or more large-scale channel properties is based comprise the antenna ports in the two or more different sets of physical resources.

22. The wireless device of claim 1 wherein the one or more large-scale channel properties include one or more of a group consisting of:

delay spread, Doppler spread, Doppler shift, average gain, and average delay.

23. A method of operation of a wireless device in a cellular communications network, comprising:

receiving a downlink subframe from the cellular communications network, the downlink subframe comprising a downlink control channel from the cellular communications network; and

estimating one or more large-scale channel properties for an antenna port of interest in the downlink control channel based on a subset of a plurality of reference signals corresponding to antenna ports in the cellular communications network that are quasi co-located with the antenna port of interest with respect to the one or more large-scale channel properties.

24. A base station of a cellular communications network, comprising:

a radio subsystem; and

a processing subsystem associated with the radio subsystem configured to;

provide, via the radio subsystem, a downlink subframe comprising a plurality of reference signals corresponding to a plurality of antenna ports according to one or more predefined rules that define one or more subsets of the plurality of antenna ports that must be quasi co-located within a downlink control channel of the downlink subframe.

25. A base station of a cellular communications network, comprising:

a radio subsystem; and

a processing subsystem associated with the radio subsystem configured to;

send, via the radio subsystem, information to a wireless device that is indicative of antenna ports that are quasi co-located within a downlink control channel of a subframe of a downlink from the cellular communications network.

26. The base station of claim 25 wherein the information is explicitly indicative of the antenna ports that are quasi co-located.

27. The base station of claim 25 wherein the information is implicitly indicative of the antenna ports that are quasi co-located.

28. The base station of claim 25 wherein the subframe includes a plurality of sets of resources for the downlink control channel, and the information is indicative of whether antenna ports within the same set of resources are quasi co-located with respect to one or more large-scale channel properties.

29. The base station of claim 28 wherein the downlink control channel is an enhanced Physical Downlink Control Channel.