PROACTIVE SCHEDULING METHODS AND APPARATUS TO ENABLE PEER-TO-PEER COMMUNICATION LINKS IN A WIRELESS OFDMA SYSTEM

• US 20100189048A1
• Filed: 01/27/2009
• Published: 07/29/2010
• Est. Priority Date: 01/27/2009
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: BONTA, Jeffrey D., MICHELS, James P., CALCEV, George, SMITH, Nathan J., MANGALVEDHE, Nitin R., BAKER, Michael H.
• Granted Patent: US 8,305,972 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• 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 5/0073 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: H04L 5/0082 at predetermined intervals
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated

Abstract

Systems, methods and apparatus are provided for scheduling resources in Orthogonal Frequency-Division Multiple Access (OFDMA) communication networks for “direct link” or peer-to-peer communications among stations operating therein so that OFDMA resources can be allocated to a transmitter station for a peer-to-peer communication session with a receiver station such that near-far issues caused by peer-to-peer communication are reduced/avoided. The disclosed technologies can prevent peer-to-peer communication links using different sub-channels within the same time slot from creating near-far issues for other receiver stations that are within communication range.

Claims

1. A method for scheduling Orthogonal Frequency-Division Multiple Access (OFDMA) resources allocated to a transmitter station for a peer-to-peer communication session with a receiver station, the method comprising:

maintaining, at the base station, a resource allocation map comprising;

particular OFDMA resources of an OFDMA frame that have been allocated to particular stations; and

generating, at a base station, a request for information with respect to selected OFDMA resources;

receiving at the base station, a resource request message (RRM) from the transmitter station to request allocation of some of the OFDMA resources for the peer-to-peer communication session with the receiver station; and

processing, at the base station, to determine specific ones of the OFDMA resources to be allocated to the transmitter station for the peer-to-peer communication session with the receiver station.

2. A method according to claim 1, wherein each of the OFDMA resources is a OFDMA frequency sub-channel within an OFDMA time slot, and wherein the request for information with respect to selected OFDMA resources comprises:

a resource map information element (RMIE), wherein the RMIE comprises;

a Partial Resource Allocation Map (PRAM), comprising;

selected OFDMA resources of the OFDMA frame that the base station is requesting more information about;

an indicator that a radio frequency (RF) quality metric is to be measured with respect to the selected OFDMA resources;

a number of first metric measurements being requested with respect to the selected OFDMA resources; and

a first metric categories field which identifies one or more first metric categories a station is to report with respect to the selected OFDMA resources, and

further comprising;

broadcasting the RMIE, from the base station to recipient stations including the transmitter station, to request first metric measurement information from the recipient stations based on information specified in the PRAM;

receiving, at the recipient stations including the transmitter station, the RMIE, and measuring first metric with respect to some of the selected OFDMA resources specified in the PRAM;

generating, at the recipient stations including the transmitter station, a resource map response message (RMRM) comprising information regarding first metric measurement with respect to some of the selected OFDMA resources, wherein the RMRM generated by the transmitter station comprises a first RMRM;

transmitting, to the base station, the respective RMRMs generated by each of the recipient stations including the first RMRM generated by the transmitter station, and the resource request message (RRM) from the transmitter station to request allocation of some of the OFDMA resources for the peer-to-peer communication session with the receiver station.

3. A method according to claim 2, wherein the specific ones of the OFDMA resources allocated to the transmitter station each comprise:

an allocated OFDMA sub-channel within a particular OFDMA time slot, and wherein the specific ones of the OFDMA resources are allocated such that other stations communicating over different OFDMA sub-channels of the particular OFDMA time slots will not cause near-far problems for the receiver station, and communications by the transmitter station using the specific ones of the OFDMA resources will not cause near-far problems for the other stations communicating over different OFDMA sub-channels of the particular OFDMA time slots.

4. A method according to claim 1, wherein the peer-to-peer communication session between the transmitter station and the receiver station takes place in an OFDMA cell defined by the base station, and further comprising:

dynamically adjusting the resource measurement information of the RMIE at the base station as traffic characteristics change within the OFDMA cell.

5. A method according to claim 2, wherein the resource request message (RRM) transmitted from the transmitter station to request allocation of some of the OFDMA resources for the peer-to-peer communication session with the receiver station, comprises:

an indicator which indicates the type of peer-to-peer communication session the transmitter station would like to set up with the receiver station including information regarding QoS requirements for that type of peer-to-peer communication session;

information regarding the station type of the transmitter station; and

information regarding the size of the packet to be transmitted by the transmitter station.

6. A method according to claim 2, wherein the step of measuring first metric with respect to some of the selected OFDMA resources specified in the PRAM, comprises:

decoding, at the recipient stations including the transmitter station, the PRAM;

starting a resource measurement period timer at each of the recipient stations including the transmitter station;

monitoring, at the recipient stations including the transmitter station, an OFDMA channel for an OFDMA frame;

selecting, at the recipient stations including the transmitter station, particular ones of the selected OFDMA resources from the PRAM; and

measuring, at the recipient stations including the transmitter station, the first metric with respect to each of the particular ones of the selected OFDMA resources that are selected by that particular recipient station.

7. A method according to claim 6, wherein the step of generating, at each of the recipient stations including the transmitter station, a resource map response message (RMRM), comprises:

sorting, at each of the recipient stations including the transmitter station, measured first metric for each of the particular ones of the selected OFDMA resources into one of a plurality of first metric categories that categorize the particular ones of the selected OFDMA resources based on measured first metric, wherein the plurality of first metric categories comprise;

a high first metric category that includes information regarding peer stations that cause high level interference;

a medium first metric category that includes information regarding peer stations that cause medium level interference, and a low first metric category that includes information regarding peer stations that cause low level interference;

generating, at each of the recipient stations including the transmitter station, a partial resource measurement map (PRMM) comprising the plurality of first metric categories, wherein each of the first metric categories includes first metric measurement information regarding some of the particular ones of the selected OFDMA resources; and

generating, at each of the recipient stations including the transmitter station upon expiration of the resource measurement period, a resource map response message (RMRM) comprising the PRMM as determined by that particular station, wherein the RMRMs generated by the transmitter station comprises the first RMRMs including first PRMMs.

8. A method according to claim 7, wherein each RMRM comprises:

a resource type field that specifies a type of resource that the particular station is reporting in the RMRM;

a total categories field that specifies a total number of different first metric categories being reported in the RMRM; and

a partial resource measurement map (PRMM) comprising;

a plurality of first metric categories each including information regarding first metric measurements made by the particular station for selected ones of the selected OFDMA resources specified in the PRAM,

wherein the plurality of first metric power categories specified in each PRMM comprise;

a high first metric category used to report high power first metric measurements, a medium first metric category used to report medium power first metric measurements, and a low first metric category used to report low power first metric measurements.

9. A method according to claim 8, wherein each of the first metric categories comprise a plurality of fields used to report information regarding first metric measurements by the particular station for that first metric power category, the plurality of fields comprising:

a category identifier field that identifies the particular first metric category;

a number measured field that specifies a number of first metric measurements that are included for the particular first metric category, and

a category MAP data field that specifies particular resource locations in the resource allocation map for the particular first metric category, wherein each particular resource location is specified as at least one specific sub-channels and at least one time slot.

10. A method according to claim 9, wherein the step of processing, at the base station, the RMRMs to determine specific ones of the OFDMA resources to be allocated to the transmitter station for the peer-to-peer communication session with the receiver station, comprises:

receiving, at the base station, the first resource map response message (RMRM) from the transmitter station;

determining, at the base station based on the RMM, a packet size the transmitter station requests to transmit in the peer-to-peer communication session with the receiver station;

determining, at the base station based on the one or more first PRMMs from the first RMRM, updated peer station information for the transmitter station; and

scheduling a first OFDMA resource in a first OFDMA time slot for a first transmission by the transmitter station to the receiver station during the peer-to-peer communication session; and

scheduling other OFDMA resources in other OFDMA time slots for other transmissions by high first metric peer stations of the receiver station having high power first metric such that the first transmission is received by the receiver station at a time when the high first metric peer stations of the receiver station are not transmitting so that the first transmission is isolated in the time domain from the other transmissions by the high first metric peer stations of the receiver station.

11. A method according to claim 10, wherein the step of determining, at the base station based on the one or more first PRMMs from the first RMRM, updated peer station information for the transmitter station, comprises:

extracting, at the base station from the one or more first PRMMs that was received from the transmitter station, information regarding first metric measurements made by the transmitter station for the selected ones of the selected OFDMA resources;

using the resource allocation map maintained at the base station to translate the selected ones of the selected OFDMA resources into corresponding peer station identification numbers;

determining, at the base station, first metric categories from the one or more first PRMMs for each of the peer station indentification numbers, and assigning each particular peer station identification number to one of;

a high power first metric transmitter peer list that specifies peer stations having high power first metric, a low power first metric transmitter peer list that specifies peer stations having low power first metric, and a medium power first metric transmitter peer list that specifies peer stations having medium power first metric;

creating, at the base station, an entry in a peer memory map (PMM) for the transmitter station, wherein the PMM comprises a plurality of rows, and a plurality of columns, the plurality of columns comprising;

a first column that lists peer station identification numbers corresponding to peer-to-peer enabled stations including the transmitter station and the receiver station, wherein each row corresponds to entry for a particular peer-to-peer enabled station that is identified in the first column by a particular peer station identification number;

a second column comprising the high power first metric transmitter peer list that specifies peer stations having high power first metric, wherein the second column lists peer station identification numbers for peer stations of the corresponding station in the first column;

a third column comprising the low power first metric transmitter peer list that specifies peer stations having low power first metric, wherein the third column lists peer station identification numbers for peer stations of the corresponding station in the first column; and

a fourth column comprising the medium power first metric transmitter peer list that specifies peer stations having medium power first metric, wherein the fourth column lists peer station identification numbers for peer stations of the corresponding station in the first column.

12. A method according to claim 11, wherein the step of scheduling comprises:

processing, at the base station, the first PRMM provided in the first RMRM and other PRMMs provided in other RMRMs from other recipient stations, to generate;

a high impact peer set that identifies stations in the high power first metric transmitter peer list of the transmitter station that are susceptible to near-far issues when one station that belongs to the high impact peer set transmits while another station that belongs to the high impact peer set is receiving a different transmission from another station that does not belong to the high impact peer set, and

a low impact peer set that identifies stations in the low power first metric transmitter peer list of the transmitter station that are not susceptible to near-far issues when one station that belongs to the low impact peer set transmits while another station that belongs to the low impact peer set is receiving a different transmission from another station that does not belong to the low impact peer set;

using information in the resource allocation map, the high impact peer set and the low impact peer set to determine preferred OFDMA time slots (TSP) of the OFDMA frame and excluded OFDMA time slots (TS_x) of the OFDMA frame, and marking the preferred OFDMA time slots (TS_p) and excluded OFDMA time slots (TS_x) in the resource allocation map maintained at the base station;

estimating, at the base station, a resource allocation size (RAS) for the peer-to-peer communication session between the transmitter station and the receiver station; and

determining, at the base station based on the estimated RAS, a resource allocation comprising at least one of the preferred OFDMA time slot (TS_p) and at least one sub-channel in that preferred OFDMA time slot (TS_p) to allocate for the peer-to-peer communication session between the transmitter station and the receiver station.

13. A method according to claim 12, wherein the step of using information in the resource allocation map, the high impact peer set and the low impact peer set to determine preferred OFDMA time slots (TS_p) of the OFDMA frame and excluded OFDMA time slots (TS_x) of the OFDMA frame, and marking the preferred OFDMA time slots (TS_p) and excluded OFDMA time slots (TS_x) in the resource allocation map maintained at the base station, comprises:

marking, at the base station, any time slots allocated to peer stations in a high impact peer set of the receiver station as excluded OFDMA time slots (TS_x) of the OFDMA frame;

marking, at the base station, any time slots allocated to peer stations in the high impact peer set of the transmitter station as preferred OFDMA time slots (TS_p) of the OFDMA frame; and

when the high impact peer set of the transmitter station includes no peer stations, marking, at the base station, any time slots allocated to peer stations in a low impact peer set of the receiver station as preferred OFDMA time slots (TS_p) of the OFDMA frame.

14. A method according to claim 13, when an OFDMA time slot is marked as being both an excluded time slot (TS_x) and preferred time slot (TSP), further comprising:

marking the OFDMA time slot;

as a preferred OFDMA time slot (TSP) of the OFDMA frame when the transmitter station is a member of the high impact peer set of the receiver station, or as an excluded OFDMA time slot (TS_x) of the OFDMA frame when the transmitter station is not a member of the high impact peer set of the receiver station.

15. A method according to claim 12, further comprising:

transmitting, from the base station to the transmitter station and the receiver station, a resource grant message (RGM) to notify the transmitter station and the receiver station of the resources allocation to the transmitter station and the receiver station for the peer-to-peer communication session between the transmitter station and the receiver station.

16. A method according to claim 2, wherein the first metric comprises a radio frequency (RF) quality metric.

17. A method according to claim 16, wherein the RF quality metric comprises:

Receive Signal Strength (RSS) power levels.

18. A method according to claim 16, wherein the RF quality metric comprises:

Signal-to-interference-plus-Noise Ratio (SINR).

19. A method according to claim 16, wherein the RF quality metric comprises:

Signal-to-Noise Ratio (SNR).

20. A method according to claim 16, wherein the RF quality metric comprises:

range.

21. A method according to claim 1, wherein the OFDMA frame comprises:

a downlink portion comprising downlink OFDMA resources for downlink communications from the base station to stations, and an uplink portion comprising uplink OFDMA resources for normal uplink communications from the stations to the base station and for direct peer-to-peer communication between stations

and wherein the resource allocation map comprises;

designations of selected ones of the downlink OFDMA resources presently allocated to stations for downlink communications from the base station to stations, and designations of selected ones of the uplink OFDMA resources presently allocated to stations for normal uplink communications from the stations to the base station and presently allocated for direct peer-to-peer communication between stations in the uplink portion of the OFDMA frame.

22. A method according to claim 21, wherein the uplink portion comprises a dedicated zone, wherein the dedicated zone comprises OFDMA resources reserved exclusively for direct station-to-station communications such that normal uplink communications from the stations to the base station can not be scheduled in the dedicated zone.

23. A method according to claim 1, wherein the base station defines a cell of an OFDMA communication system, and wherein the OFDMA communication system comprises:

a wide area wireless OFDMA communication network.

24. A method for scheduling OFDMA resources allocated to a transmitter station for a peer-to-peer communication session with a receiver station, the method comprising:

transmitting, from a base station to recipient stations including the transmitter station, a metric request message to request first metric measurement information from the recipient stations, wherein the metric request message comprises;

an indicator that first metric is to be measured with respect to selected OFDMA resources of an OFDMA frame that the base station is requesting more information about; and

one or more first metric categories that a station is to report with respect to the selected OFDMA resources;

receiving the metric request message at the recipient stations including the transmitter station, measuring, at each of the at the recipient stations, first metric with respect to some of the selected OFDMA resources, and transmitting, from each of the recipient stations, a response message (RM) comprising information regarding first metric measurement with respect to some of the selected OFDMA resources, wherein the response message (RM) generated by the transmitter station comprises a first response message (RM);

transmitting, to the base station, a resource request message (RRM) from the transmitter station to request allocation of some of the OFDMA resources for the peer-to-peer communication session with the receiver station; and

processing the response messages (RMs) at the base station to determine specific ones of the OFDMA resources to be allocated to the transmitter station.

25. A method for scheduling OFDMA resources allocated to a transmitter station for a peer-to-peer communication session with a receiver station, the method comprising:

transmitting, from a base station to recipient stations including the transmitter station, a request for first metric measurement information to be measured with respect to selected OFDMA resources of an OFDMA frame;

receiving the request message at the recipient stations;

measuring, at each of the recipient stations, first metric with respect to some of the selected OFDMA resources, and transmitting, from each of the recipient stations, a response message (RM) comprising information regarding first metric measurements with respect to some of the selected OFDMA resources; and

processing the response messages (RMs) at the base station to determine specific ones of the OFDMA resources to be allocated to the transmitter station for the peer-to-peer communication session with the receiver station.