System and method for inter-cell interference avoidance in co-channel networks

• US 8,442,541 B2
• Filed: 03/28/2011
• Issued: 05/14/2013
• Est. Priority Date: 03/29/2010
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Guvenc, Ismail, Jeong, Moo Ryong, Watanabe, Fujio
• Primary Examiner(s): Bhattacharya, Sam
• Application Number:
  US13/073,137
• Publication Number:
  US 20110237243A1
• Time in Patent Office: 778 Days
• Field of Search: 455/418, 455/423, 455/436, 455/450, 370/252, 370/335, 370/336
• US Class Current: 455/450
• CPC Class Codes: H04L 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04L 5/0058 Allocation criteria
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

Systems and methods are provided for a distributed inter-cell interference avoidance (ICIA) technique for avoiding co-channel interference between femtocell networks and macrocell networks. At the macrocell, user equipments sense the downlink (DL) spectrum and detects whether there are any nearby interfering femtocells. If there is any interference, a macrocell base station appropriately re-schedules the DL resources and also uses a mapping function to re-schedule uplink (UL) resources based on the re-scheduled DL resources. At the femtocell, a femtocell base station senses the UL spectrum to detect for interference from nearby macrocell users. If there is interference, femtocell gives priority for use of the resources to the macrocell by releasing UL resources. Femtocell may also use the same mapping function to obtain the DL resources used by the macrocell and to re-schedule DL and UL resources of the femtocell to avoid using the DL and UL resources of the macrocell.

Claims

1. A method, comprising:

sensing downlink (DL) interference at a macrocell mobile station of a macrocell network from a femtocell base station of a co-channel femtocell network within a coverage area of the macrocell network, wherein the macrocell mobile station is initially scheduled in the DL in resource blocks spanning a first bandwidth;

re-scheduling uplink (UL) and DL spectrum resources for the macrocell mobile station to address the interference such that the mobile station is rescheduled in the DL in first resource blocks spanning a second bandwidth that is less than the first bandwidth;

sensing a change in UL interference at the femtocell base station responsive to the re-scheduling for the macrocell mobile station; and

re-scheduling femtocell UL and DL spectrum resources for a femtocell mobile station within the femtocell network to address the change in UL interference such that the re-scheduling in the UL for the femtocell network avoids at least some of the first resource blocks.

2. The method of claim 1, wherein said re-scheduling UL and DL spectrum resources for the macrocell mobile station comprises:

using a DL/UL mapping function to map the re-scheduled DL resources to generate re-scheduled UL resources.

3. The method of claim 2, wherein said re-scheduling UL and DL spectrum resources for the femtocell mobile station comprises:

re-scheduling the UL resources of the femtocell network to avoid using UL resources of the femtocell network sensed as receiving interference from the macrocell network;

using the DL/UL mapping function to map the UL resources of the femtocell network sensed as receiving interference from the macrocell network to determine DL resources of the femtocell network expected to receive interference from the macrocell network; and

re-scheduling DL resources of the femtocell network to avoid using the DL resources of the femtocell network expected to receive interference from the first cellular network.

4. The method of claim 1, wherein said sensing DL interference comprises generating an interference table to identify victim macrocell mobile stations.

5. The method of claim 4, wherein said re-scheduling DL resources of the first cellular network comprises re-scheduling DL resources for the victim macrocell mobile stations.

6. The method of claim 1, wherein the DL resources and the UL resources for the macrocell network and the femtocell network comprises a plurality of component carriers.

7. The method of claim 1, wherein said sensing DL interference and sensing a change in UL interference comprises detecting energy of the interference and comparing the energy to a detection threshold, wherein the detection threshold is set high enough to minimize false alarm.

8. A macrocell base station configured for inter-cell interference avoidance comprising:

a re-scheduler module adapted to re-schedule uplink (UL) and DL spectrum resources of a macrocell network responsive to reception from a macrocell mobile station of an identification of DL resource blocks in which the macrocell mobile station detected interference from a femtocell base station such that the macrocell mobile station is re-scheduled in DL resource blocks spanning a reduced bandwidth.

9. The macrocell base station of claim 8, wherein the re-scheduler module further comprises:

a DL re-scheduler module of the first cellular network adapted to generate re-scheduled DL resources; and

a memory containing a DL/UL mapping table adapted to generate re-scheduled UL resources from the re-scheduled DL resources.

10. The macrocell base station of claim 9, wherein the base station is further adapted to transmit the re-scheduled DL resources and the re-scheduled UL resources to the macrocell mobile station.

11. A femtocell base station for a femtocell network comprising:

an uplink (UL) spectrum sensing module adapted to detect a change in UL interference from a macrocell network; and

a re-scheduler module, wherein the re-scheduler module is adapted to;

re-schedule UL resources of the femtocell network to avoid using UL resources of the femtocell network sensed as receiving interference from the macrocell network; and

re-schedule DL resources of the femtocell network based upon a DL-to-UL mapping.