NETWORK-CENTRIC LINK ADAPTATION FOR COORDINATED MULTIPOINT DOWNLINK TRANSMISSION

• US 20120275327A1
• Filed: 06/07/2012
• Published: 11/01/2012
• Est. Priority Date: 06/12/2009
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Zangi, Kambiz, Hui, Dennis, Hafeez, Abdulrauf
• Granted Patent: US 8,849,326 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04J 11/0053 using co-ordinated multipoint transmission/reception co-ordinated antenna or beam-forming aspects H04B7/022
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/0022 in which mode-switching is influenced by the user
• CPC Class Codes: H04L 1/0034 where the transmitter decides based on inferences, e.g. use of implicit signalling
• CPC Class Codes: H04L 1/02 by diversity reception
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0073 Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005

Abstract

A Coordinated MultiPoint (CoMP) cell controller performs network-centric link adaptation for User Equipment (UE) in the CoMP cell. The CoMP cell controller receives at least infrequent channel estimates from a UE in the CoMP cell, from which it estimates downlink channel and thermal noise at the UE. The CoMP cell controller is aware of the desired signal to be received at the UE, and the intra-CoMP cell interference to the UE caused by transmissions to other UEs in the CoMP cell. The CoMP cell receives from the UE reports of inter-CoMP cell interference caused by transmissions by other CoMP cells. Based on the downlink channel quality, the desired signal, the intra-CoMP cell interference, the inter-CoMP cell interference, and the thermal noise, the CoMP cell controller performs link adaptation by selecting modulation and coding schemes, and other transmission parameters, for an upcoming transmission duration (such as a TTI).

Claims

1. A method of network-centric link adaptation for a first User Equipment (UE), performed by a controller of a first Coordinated Multi-Point (CoMP) cooperating set consisting of a single network transceiver that serves a plurality of UEs in a single cell, comprising:

determining the downlink channel quality between the single network transmitter in the first CoMP cooperating set and the first UE;

determining the desired signal to be received at the first UE;

determining the interference caused to the first UE by transmissions to other UEs in the first CoMP cooperating set;

determining the thermal noise observed at the first UE; and

performing link adaptation for the first UE based on the downlink channel quality, the desired signal, the intra-CoMP cooperating set interference, and the thermal noise.

2. The method of claim 1 further comprising receiving, from the first UE, a measure of interference from one or more other CoMP cooperating sets, and wherein performing link adaptation for the first UE further comprises performing link adaptation also based on inter-CoMP cooperating set interference.

3. The method of claim 2 wherein receiving a measure of interference from other CoMP cooperating sets comprises receiving a measure of interference observed by the first UE when no network transceiver in the first CoMP cooperating set transmits symbols.

4. The method of claim 2 wherein receiving, from the first UE, a measure of interference from other CoMP cooperating sets comprises receiving a frequency-independent measure of interference from other CoMP cooperating sets.

5. The method of claim 3 wherein receiving a frequency-independent measure of interference from other CoMP cooperating sets comprises receiving a measure of observed interference from other CoMP cooperating sets averaged over sub-carrier and time.

6. The method of claim 2 wherein receiving, from the first UE, a measure of interference from other CoMP cooperating sets comprises receiving, from the first UE, a measure of interference from other CoMP cooperating sets and thermal noise.

7. The method of claim 2 wherein performing link adaptation for the first UE comprises estimating the Signal to Interference and Noise Ratio (SINR) for the first UE at sub-carrier “

k” and

time “

t”

as;

8. A Coordinated Multi-Point (CoMP) cell controller, comprising:

a communication interface to a single network transceiver in a CoMP cooperating set, the single network transceiver providing wireless communications to a plurality of User Equipments (UE) within a single cell of the CoMP cooperating set; and

a controller operative to communicate transmission parameters to the single network transceiver so as to maximize the data rate to selected UEs and while presenting interference to other UEs in the CoMP cooperating set below a predetermined amount, and further operative to perform link adaptation by

determining the downlink channel quality between the one or more network transmitters in the first CoMP cooperating set and the first UE;

determining the desired signal to be received at the first UE;

determining the interference caused to the first UE by transmissions to other UEs in the first CoMP cooperating set;

determining the thermal noise observed at the first UE; and

performing link adaptation for the first UE based on the downlink channel quality, the desired signal, the intra-CoMP cooperating set interference, and the thermal noise.

9. The controller of claim 8 wherein the controller is further operative to receive, from the first UE, a measure of interference from one or more other CoMP cooperating sets, and wherein the controller is operative to perform link adaptation for the first UE also based on inter-CoMP cooperating set interference.

10. The controller of claim 9 wherein the controller is operative to receive a measure of interference from other CoMP cooperating sets observed by the first UE when no network transceiver in the first CoMP cooperating set transmits symbols.

11. The controller of claim 9 wherein the controller is operative to receive, from the first UE, a frequency-independent measure of interference from other CoMP cooperating sets.

12. The controller of claim 11 wherein the controller is operative to receive, from the first UE, a frequency-independent measure of interference from other CoMP cooperating sets averaged over sub-carrier and time.

13. The controller of claim 9 wherein the controller is operative to receive, from the first UE, a measure of interference from other CoMP cooperating sets and thermal noise.

14. The controller of claim 9 wherein the controller is operative to perform link adaptation for the first UE by estimating the Signal to Interference and Noise Ratio (SINR) for the first UE at sub-carrier “

k” and

time “

t”

as;