OFDMA CELLULAR NETWORK AND METHOD FOR MITIGATING INTERFERENCE

• US 20100317339A1
• Filed: 06/11/2009
• Published: 12/16/2010
• Est. Priority Date: 06/11/2009
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Koc, Ali Taha
• Granted Patent: US 8,238,323 B2
• Time in Patent Office: Days
• US Class Current: 455/424
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/003 Arrangements for allocating sub-channels of the transmission path
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• 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 72/121 for groups of terminals or users
• CPC Class Codes: H04W 72/1268 of uplink data flows
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

Embodiments of an OFDMA cellular network and method for mitigating interference are generally described herein. In some embodiments, the scheduler assigns a common group ID to mobile stations based on interference levels of a common interference source and allocates bandwidth within a selected zone of an OFDMA uplink subframe to the mobile stations assigned the common group ID for uplink communications within the uplink subframe. In some joint-scheduling embodiments, a neighbor base station that is identified as the common interference source may refrain from assigning bandwidth within the selected zone to at least some of its associated mobile stations that have identified the serving base station as an interference source.

Claims

1. A base station configured to mitigate uplink interference in an orthogonal frequency division multiple access (OFDMA) cellular network, the base station comprising a scheduler configured to:

assign a common group identifier (ID) to mobile stations based on interference levels of a common interference source; and

allocate bandwidth within a selected zone of an OFDMA uplink subframe to the mobile stations assigned the common group ID for uplink communications with the base station within the uplink subframe.

2. The base station of claim 1 wherein a neighbor base station that is identified as the common interference source is configured to refrain from assigning bandwidth within the selected zone to at least some of its associated mobile stations that have identified the serving base station as an interference source.

3. The base station of claim 2 wherein the scheduler is further configured to:

receive scan reports from associated mobile stations identifying one or more interference sources and the interference level associated with at least one of the interference sources; and

identify common interference sources based on an identity of the interference sources from the scan reports.

4. The base station of claim 3 wherein the scheduler is configured to assign a common group ID to mobile stations with a common interference source when the interference level of the common interference source is above a predetermined threshold.

5. The base station of claim 4 wherein the scheduler is further configured to cause the base station to transmit a group ID broadcast message to the mobile stations that are assigned the common group IDs, and

wherein the group ID broadcast message is configured to include the assigned group ID, and frequency assignments for each of the mobile stations assigned the common group ID.

6. The base station of claim 5 wherein the allocated zone is an orthogonal zone in time of the OFDMA uplink subframe, and

wherein within the allocated zone, the allocated bandwidth comprises an orthogonal channel resource in frequency that is allocated to each of the mobile stations having a common group ID for uplink communications within the OFDMA uplink subframe.

7. The base station of claim 6 wherein the scheduler is further configured to assign the orthogonal channel resource to each of the mobile stations with a common group ID based on a channel response determined from a channel sounding signal transmitted by the mobile stations.

8. The base station of claim 4 wherein the scheduler is configured to refrain from assigning a common group ID to mobile stations that do not have an interference level of a common interference source above the predetermined threshold, and

wherein the scheduler is further configured to allocate bandwidth to mobile stations that do not have an interference level of a common interference source above the predetermined threshold from portions of the uplink subframe that is not within the selected zone.

9. The base station of claim 4 wherein the base station is a serving base station,

wherein the scheduler is further configured to generate interference reports for transmission to a neighbor base station identified as common interference sources, and

wherein the interference report identifies the selected zone of the OFDMA uplink subframe that the serving base station has assigned to mobile stations that have identified the neighbor base station as the common interference source.

10. The base station of claim 9 wherein the serving base station and the neighbor base station are configured to utilize a same frequency range and time-synchronize their OFDMA frames.

11. The base station of claim 9 wherein in response to receipt of the interference report, the neighbor base station is configured to assign a different zone of the OFDMA uplink subframe to at least some of its associated mobile stations that have identified the serving base station as a common interference source,

wherein the cellular network is a Worldwide Interoperability for Microwave Access (WiMAX) cellular network and the base station is configured to communicate in accordance with one of the IEEE 802.16m specifications using an OFDMA technique comprising time-division multiplexed downlink and uplink subframes.

12. The base station of claim 1 wherein the cellular network is a 3rd Generation Partnership Project (3GPP) Universal Terrestrial Radio Access Network (UTRAN) Long-Term Evolution (LTE) cellular network and the base station is configured to communicate in accordance with one of the 3GPP UTRAN LTE communication standards,

wherein the mobile stations transmit uplink subframes to an associated base station using single-carrier uplinks;

and

wherein the base stations communicate within downlink subframes to associated mobile stations using multicarrier downlinks.

13. A scheduler to operate in an orthogonal frequency division multiple access (OFDMA) cellular network configured to:

receive interference reports at a serving base station from mobile stations identifying interference sources; and

instruct a neighbor base station that is identified as a common interference source to refrain from assigning bandwidth within a selected zone of an OFDMA uplink subframe to at least some of its associated mobile stations that have identified the serving base station as an interference source.

14. The scheduler of claim 13, wherein the scheduler is further configured to:

assign a common group identifier (ID) to at least some of the mobile stations based on interference levels of the common interference source based on the interference reports; and

allocate bandwidth within the selected zone of the OFDMA uplink subframe to the mobile stations assigned the common group ID for uplink communications within the uplink subframe.

15. The scheduler of claim 13 wherein the OFDMA cellular network operations in accordance with a frequency reuse pattern of one,

wherein the serving base station and the neighbor base station are configured to time-synchronize their OFDMA frames, and

wherein the OFDMA cellular network is a Worldwide Interoperability for Microwave Access (WiMAX) cellular network and the base station is configured to communicate in accordance with one of the IEEE 802.16m specifications using an OFDMA technique comprising time-division multiplexed downlink and uplink subframes.

16. The scheduler of claim 15 wherein the scheduler is configured to:

assign a common group ID to mobile stations with a common interference source when the interference level of the common interference source is above a predetermined threshold; and

cause the base station to transmit a group ID broadcast message to the mobile stations that are assigned the common group IDs,

wherein the allocated zone is an orthogonal zone in time of the OFDMA uplink subframe.

17. A method of scheduling uplink communications in an OFDMA cellular network, the method comprising:

assigning a common group identifier (ID) by a serving base station to mobile stations based on interference levels of a common interference source; and

instructing a neighbor base station that is identified as the common interference source to refrain from assigning bandwidth within a selected zone of an OFDMA uplink subframe to at least some of its associated mobile stations that have identified the serving base station as an interference source.

18. The method of claim 17 further comprising allocating bandwidth within the selected zone of the OFDMA uplink subframe to the mobile stations assigned the common group ID for uplink communications with the serving base station within the uplink subframe.

19. The method of claim 17 further comprising:

receiving scan reports from associated mobile stations identifying one or more interference sources and the interference level associated with at least one of the interference sources;

identifying common interference sources based on an identity of the interference sources from the scan reports; and

assigning a common group ID to mobile stations with a common interference source when the interference level of the common interference source is above a predetermined threshold.

20. The method of claim 17 wherein the OFDMA cellular network operates in accordance with a frequency reuse pattern of one, and

wherein the serving base station and neighbor base stations are configured to time-synchronize their OFDMA frames.