Neighbour cell quality measurement in a telecommunications system

• US 8,693,463 B2
• Filed: 03/09/2009
• Issued: 04/08/2014
• Est. Priority Date: 03/13/2008
• Status: Active Grant

• Current Assignee: IDTP Holdings Incorporated (InterDigital, Inc.)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Kazmi, Muhammad, Jongren, George
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): MAGLO, EMMANUEL K
• Application Number:
  US12/921,853
• Publication Number:
  US 20110007657A1
• Time in Patent Office: 1,856 Days
• Field of Search: 370/330, 370/252, 370/329, 455/423, 455/63.1
• US Class Current: 370/352
• CPC Class Codes: H04J 11/005 of intercell interference
• CPC Class Codes: H04J 11/0093 Neighbour cell search
• CPC Class Codes: H04L 5/0039 Frequency-contiguous, i.e. with no allocation of frequencies for one user or terminal between the frequencies allocated to another
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• 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
• CPC Class Codes: H04W 36/0085 Hand-off measurements

Abstract

The present invention relates to methods and arrangements for neighbor cell quality measurements using silent resource element (RE) grids, and as well to a silent RE grid.

Claims

1. A method, executed in a first network node of a wireless communication system, for measuring a quality of a neighbor cell for mobility purposes, the method comprising:

obtaining a cell-specific silent grid for measuring the quality of a neighbor cell, the cell-specific silent grid comprising resource elements having no data allocation;

measuring signal interference over said grid during a measurement period in one or more of the resource elements of said grid having no data allocation; and

estimating the quality of the neighbor cell based on the measured signal interference;

wherein the quality of the neighbour cell is calculated based on an inter-cell interference measured or estimated during the cell-specific silent grid by using signal strength and interference.

2. A method according to claim 1, further comprising a step of reporting said estimated quality of the neighbor cell to a second network node.

3. A method according to claim 1, wherein the inter-cell interference comprises noise and a received power from a data channel or a control channel, or a combination thereof.

4. A method according to claim 1, further comprising calculating the quality of the neighbor cell as a Reference Symbol Received Quality (RSRQ) using the following equation:

RSRQ=RSRP/(I_inter-cell+N₀),

where RSRP=Reference Symbol Received Power, I_inter-cell=inter-cell interference measured during the silent resource element grid used in cell i, and N₀=noise.

5. A method according to claim 1, further comprising defining a position in the cell-specific silent grid of the resource elements having no data allocation, as a function of a cell ID of the cell corresponding to the cell-specific silent grid.

6. A method according to claim 1, further comprising

deriving the cell-specific silent grid for the first network node, from a cell ID of the neighbor cell;

and

making the cell-specific silent grid known to the first network node.

7. A method according to claim 1, further comprising signaling or sending an index of the cell-specific silent grid, to the first network node, via at least one control channel.

8. A method according to claim 7, wherein the at least one control channel is a broadcast channel mapped on, or sent via, a physical downlink shared channel (PDSCH).

9. An arrangement in a first network node, comprising a transceiver and a processor, said processor configured to:

obtaining a cell-specific silent grid to measure a quality of a neighbor cell, the cell-specific silent grid comprising data resource elements with no data allocation;

measure an inter-cell interference during said silent grid over a measurement period in one or more of the data resource elements of said silent grid with no data allocation; and

estimate the quality of the neighbor cell based on the measured signal interference;

wherein the quality of the neighbour cell is calculated as an inter-cell interference measured or estimated during the cell-specific silent grid by using signal strength and interference.

10. A arrangement according to claim 9, further configured to report said estimated quality of the neighbor cell to a second network node.

11. An arrangement according to claim 9, wherein the inter-cell interference comprises noise and a received power from a data channel or control channel, or a combination thereof.

12. An arrangement according to claim 9, wherein the first arrangement is configured to estimate the quality of the neighbor cell based on calculating a Reference Symbol Received Quality (RSRQ) using the following equation:

RSRQ=RSRP/(I_inter-cell+N₀),

where RSRP=Reference Symbol Received Power, I_inter-cell=inter-cell interference measured during the cell-specific silent grid used in the neighbor cell and N₀=noise.

13. An arrangement according to claim 9, further configured to define the position in the cell-specific silent grid as a function of a cell ID of the neighbor cell.

14. An arrangement according to claim 9, wherein:

the cell-specific silent grid is derived from a cell ID of the neighbor cell; and

the cell-specific silent grid is made known to the first network node.

15. An arrangement according to claim 9, further configured to transmit an index of the cell-specific silent grid to the first network node, via one or more control channels.

16. An first arrangement according to claim 15, wherein the arrangement is configured to transmit the index of the cell-specific silent grid via a secondary or a dedicated broadcast channel (D-BCH), or a physical downlink shared channel (PDSCH).