METHOD AND APPARATUS FOR A CLUSTER SPECIFIC CLOUD RADIO TRANSMISSION AND RECEPTION

• US 20180019899A1
• Filed: 01/19/2017
• Published: 01/18/2018
• Est. Priority Date: 07/14/2016
• Status: Active Grant

• Current Assignee: Indian Institute of Technology Hyderabad
• Original Assignee: Indian Institute of Technology Hyderabad
• Inventors: Kuchi, Kiran Kumar
• Granted Patent: US 11,012,263 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 5/0026 Division using four or more dimensions
• CPC Class Codes: H04L 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04W 72/27 between access points
• CPC Class Codes: H04W 88/085 Access point devices with remote components

Abstract

Embodiments herein provide a method implemented in a cloud radio access network (C-RAN). The method includes transmitting channel state information (CSI) reference signals to plurality of user equipments (UEs). The method includes receiving a measured downlink (DL) CSI from each UE among the plurality of UEs. The DL CSI corresponds to a plurality of antenna ports associated with a set of remote radio heads (RRHs) in cluster. Further, the method includes estimating an uplink (UL) CSI for each UE antenna port. The UL CSI is estimated using a pre-defined pilot structure received from each UE. The DL CSI or UL CSI is defined with respect to BS and UE antenna port pair. Furthermore, the method includes deriving a calibration coefficient for each antenna port based on measured DL CSI and estimated UL CSI. The calibrated DL CSI is used to precoder the data using a linear or non-linear precoder.

Claims

1. A method implemented in a cloud radio access network (C-RAN), the method comprising:

transmitting a channel state information (CSI) reference signals to a plurality of user equipments (UEs);

receiving a measured downlink (DL) CSI from each UE among the plurality of UEs, wherein the DL CSI corresponds to a plurality of antenna ports associated with a set of remote radio heads (RRHs) in a cluster;

estimating an uplink (UL) CSI for each UE antenna port, wherein the UL CSI is estimated using a pre-defined pilot structure received from each UE; and

deriving a calibration coefficient for each RRH and UE antenna port pair based on the measured DL CSI and the estimated UL CSI.

2. The method of claim 1, wherein the method further comprises transmitting data to each UE by precoding with diagonal element signaling (DES) pilots through the RRH.

4. The method of claim 1, wherein the method further comprises:

transmitting an uplink (UL) sounding signal with a pre-defined pilot structure to the cloud RAN;

receiving a signal from a RRH along with diagonal element signaling (DES) pilots, wherein the received signal includes data intended to the UE;

estimating the diagonal elements using DES pilots in the received signal; and

retrieving the data from the signal based on the estimated diagonal elements.

3. A method implemented in a user equipment (UE), the method comprising:

transmitting a measured downlink (DL) CSI to a cloud radio access network (C-RAN), wherein the DL CSI corresponds to a plurality of antenna ports associated with a set of remote radio heads (RRHs).

5. A cloud radio access network (C-RAN) comprising:

a reference signals transmission unit configured to;

transmit a channel state information (CSI) reference signals to a plurality of user equipments (UEs);

a downlink CSI reception unit configured to;

receive a measured downlink (DL) CSI from each UE among the plurality of UEs, wherein the DL CSI corresponds to a plurality of antenna ports associated with a set of remote radio heads (RRHs) in a cluster;

an uplink CSI estimation unit configured to;

estimate an uplink (UL) CSI for each UE antenna port, wherein the UL CSI is estimated using a pre-defined pilot structure received from each UE; and

a calibration coefficient derivation unit configured to;

derive a calibration coefficient for each RRH and UE antenna port pair based on the measured DL CSI and the estimated UL CSI.

6. The method of claim 5, wherein the C-RAN further comprises a transmitter unit configured to transmit data to each UE by precoding with diagonal element signaling (DES) pilots through the RRH.

7. The method of claim 5, wherein the transmitter unit configured to transmit data using a precoder, wherein the precoder is one of a linear precoder and a non-linear precoder.

8. A user equipment (UE) comprising:

a downlink CSI transmission unit configured to;

transmit a measured downlink (DL) CSI to a cloud radio access network (C-RAN), wherein the DL CSI corresponds to a plurality of antenna ports associated with a set of remote radio heads (RRHs).

9. The UE of claim 8, wherein the UE further comprises:

a signal reception unit configured to;

transmit an uplink (UL) sounding signal with a pre-defined pilot structure to the cloud RAN;

receive a signal from a RRH along with diagonal element signaling (DES) pilots, wherein the received signal includes data intended to the UE;

a pilots estimation unit configured to;

estimate the diagonal elements using DES pilots in the received signal; and

a data retrieval unit configured to;

retrieve data from the signal based on the estimated diagonal elements.

10. The UE of claim 8, wherein the transmitter unit configured to transmit data using a precoder, wherein the precoder is one of a linear precoder and a non-linear precoder.

11. A computer program product comprising computer executable program code recorded on a computer readable non-transitory storage medium, the computer executable program code when executed causing the actions including:

transmitting a channel state information (CSI) reference signals to a plurality of user equipments (UEs);

receiving a measured downlink (DL) CSI from each UE among the plurality of UEs, wherein the DL CSI corresponds to a plurality of antenna ports associated with a set of remote radio heads (RRHs) in a cluster;

estimating an uplink (UL) CSI for each UE, wherein the UL CSI is estimated using a pre-defined pilot structure received from each UE antenna port; and

deriving a calibration coefficient for each RRH and UE antenna port pair based on the measured DL CSI and the estimated UL CSI.

12. A computer program product comprising computer executable program code recorded on a computer readable non-transitory storage medium, the computer executable program code when executed causing the actions including:

transmitting a measured downlink (DL) CSI to a cloud radio access network (C-RAN), wherein the DL CSI corresponds to a plurality of antenna ports associated with a set of remote radio heads (RRHs).