Method and apparatus for measuring interference in a telecommunications system

• US 8,358,979 B2
• Filed: 02/04/2009
• Issued: 01/22/2013
• Est. Priority Date: 02/04/2009
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Astely, David, Hammarwall, David, Jngren, George, Lundevall, Per Magnus
• Primary Examiner(s): Wells, Kenneth B.
• Application Number:
  US12/365,703
• Publication Number:
  US 20100197330A1
• Time in Patent Office: 1,448 Days
• Field of Search: 455/63.1, 455/67.13, 370/330
• US Class Current: 455/63.1
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04L 5/003 Arrangements for allocating sub-channels of the transmission path
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0062 Avoidance of ingress interference, e.g. ham radio channels
• 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
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports

Abstract

A method for facilitating noise and interference measurements on an air interface of a wireless network includes obtaining information relating to a time-varying layout of a silent resource element (RE) grid and taking a presence of a silent RE grid into account in the reception of a control or a data channel.

Claims

1. A method in a receiving unit of a wireless network, for facilitating noise and interference measurements on an air interface, said method comprising the steps of:

obtaining, at a receiver, information relating to a time-varying layout of a first silent resource element (RE) grid for a first cell;

measuring a signal that is received on a data channel during an RE for which no data transmission is allocated for the first cell according to the silent RE grid;

determining an amount of inter-cell interference experienced by the receiver based on the signal measurement;

taking the determined inter-cell interference into account in the reception of a control or a data channel; and

introducing a second silent RE grid on a control channel to estimate an interference that hits the control channel using code in an electronic memory.

2. The method according to claim 1, wherein said step of obtaining information comprises the steps of using a pseudo-random sequence to generate said layout of said silent RE grid, and synchronizing said pseudo-random sequence by deriving a seed for said pseudo-random sequence from parameters.

3. The method according to claim 2, wherein said pseudo-random sequence is synchronized in each frame based on said parameters that include a cell ID and a frame index.

4. The method according to claim 1, wherein said layout of said silent RE grid is received through signaling.

5. The method according to claim 1, wherein determining the amount of inter-cell interference experienced by the receiver comprises:

collecting statistics relating to inter-cell interference based on measurements on said silent RE grid in an electronic memory having code; and

using said statistics with the code to estimate any or all of;

a channel quality indicator, inter-cell power that hits a channel, a co-variance matrix of the inter-cell interference that hits the channel, a full probability distribution of the Inter-cell interference.

6. The method according to claim 1 including the step of randomizing the silent RE grid in consecutive, in frequency and time, resource blocks (RBs).

7. The method according to claim 1 including the step of deriving the silent RE grid with essentially no signaling overhead.

8. The method as described in claim 1 including the step of coordinating each silent grid of neighboring cells in said wireless system such that there is no significant overlap.

9. The method as described in claim 1, wherein for each subframe, grouping resource blocks into resource windows where each resource window is a group of contiguous, in frequency, resource blocks;

and the number of resource blocks in each resource window may be configured semi-statically, each resource window having a same number of silent REs, and are configured semi-statically.

10. A receiving unit of a wireless network, for facilitating noise and interference measurements on an air interface comprising:

a network interface configured to obtain information relating to a time-varying layout of a first silent resource element (RE) grid for a first cell;

an electronic memory having code configured to communicate with the network interface and to the information; and

a processing unit configured to;

measure a signal that is received on a data channel during an RE for which no data transmission is allocated for the first cell according to the silent RE grid;

determine an amount of inter-cell interference experienced by the receiver based on the signal measurement;

take the determined inter-cell interference into account in the reception of a control or a data channel; and

introducing a second silent RE grid on a control channel to estimate an interference that hits the control channel using code in an electronic memory.

11. The receiving unit as described in claim 10 wherein the processing unit is further configured to use a pseudo-random sequence to generate the layout of the silent RE grid, and synchronizes the pseudo-random sequence by deriving a seed for the pseudo-random sequence from parameters.

12. The receiving unit as described in claim 11 wherein the processing unit is configured to synchronize the pseudo-random sequence in each frame based on parameters that include a cell ID and a frame index, and the network interface is configured to receive the layout of the silent RE grid through signaling.

13. The receiving unit as described in claim 12 wherein the electronic memory is configured to collect statistics relating to inter-cell interference based on measurements on the silent RE grid.

14. The receiving unit as described in claim 13 wherein the processing unit is configured to use the statistics with the code to estimate any or all of:

a channel quality indicator, inter-cell power that hits a channel, a co-variance matrix of the inter-cell interference that hits the channel, a full probability distribution of the Inter-cell interference; and

to send the signal through the network interface.

15. The receiving unit as described in claim 14 wherein the processing unit is configured to randomize the silent RE grid in consecutive, in frequency and time, resource blocks (RBs).

16. The receiving unit as described in claim 15 wherein the processing unit is configured to derive the silent RE grid with essentially no signaling overhead.

17. The receiving unit as described in claim 10 wherein the processing unit is configured to coordinate each silent grid of neighboring cells in the wireless system such that there is no significant overlap.

18. The receiving unit as described in claim 17 wherein for each subframe, the processing unit is configured to group resource blocks into resource windows where each resource window is a group of contiguous, in frequency, resource blocks;

and wherein the number of resource blocks in each resource window may be configured semi-statically, and each resource window has a same number of silent REs, and are configured semi-statically.