APPARATUS AND METHOD FOR ALLOCATING RESOURCES IN A WIRELESS COMMUNICATION SYSTEM

Abstract

An apparatus and method for allocating resources in a wireless communication system are provided. The apparatus and method include a BS for allocating downlink resources periodically to predetermined MSs, for generating resource allocation messages with resource allocation information for the MSs, and for transmitting control information including the resource allocation messages to the MSs. Accordingly, the apparatus and method more efficiently allocate resources in a wireless communication system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of certain exemplary embodiments of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a conventional downlink resource allocation method in a wireless communication system;

FIG. 2 is a block diagram illustrating a BS according to an exemplary embodiment of the present invention;

FIG. 3 is a block diagram illustrating an MS according to an exemplary embodiment of the present invention;

FIG. 4 is a flowchart illustrating an operation of a BS for periodically allocating downlink resources in a wireless communication system according to an exemplary embodiment of the present invention;

FIG. 5 is a flowchart illustrating an operation of an MS for receiving downlink data in a wireless communication system according to an exemplary embodiment of the present invention;

FIG. 6 is a flowchart illustrating an operation of a BS for temporarily discontinuing and resuming periodic downlink resource allocation in a wireless communication system according to an exemplary embodiment of the present invention;

FIG. 7 is a flowchart illustrating an operation of an MS for receiving data when periodic downlink resource allocation is temporarily discontinued in a wireless communication system according to an exemplary embodiment of the present invention;

FIG. 8 is a view illustrating a downlink resource allocation method in a wireless communication system according to an exemplary embodiment of the present invention;

FIG. 9 is a view illustrating a downlink resource allocation method in a wireless communication system according to another exemplary embodiment of the present invention; and

FIG. 10 is a view illustrating a downlink resource allocation method in a wireless communication system according to an exemplary embodiment of the present invention.

Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of the exemplary embodiments of the present invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

An exemplary embodiment of the present invention provides an apparatus and method for periodically allocating downlink resources in a wireless communication system. While the present invention is described in the context of an OFDM or Orthogonal Frequency Division Multiple Access (OFDMA) communication system using multiple carriers, it is to be understood that downlink Periodic Allocation (PA) of the present invention is applicable to other communication systems.

FIG. 2 is a block diagram illustrating a BS according to an exemplary embodiment of the present invention. The BS includes a periodic/non-periodic data transmitter 201, a downlink resource allocator 203, a MAP generator 205, and a MAP transmitter 207.

Referring to FIG. 2, the periodic/non-periodic data transmitter 201 encodes and modulates periodic/non-periodic data received from a higher layer in a predetermined scheme. The transmitter 201 maps the modulated data to downlink resources allocated to MSs, processes the mapped data by OFDM modulation, upconverts the OFDM-modulated data to Radio Frequency (RF) signals, and transmits the RF signals to the MSs through an antenna (not shown).

The downlink resource allocator 203 determines the MSs to which the downlink resources are to be allocated, allocates the downlink resources to the MSs according to the channel information and service types of the respective MSs, and provides the downlink resource allocation result to the MAP generator 205 and the periodic/non-periodic data transmitter 201. In addition to its typical functions, the downlink resource allocator 203 allocates periodic downlink resources to MSs that require periodic data transmission in a predetermined allocation scheme according to an exemplary embodiment of the present invention.

The MAP generator 205 generates resource allocation messages for the respective MSs according to the downlink resource allocation result and creates MAP information including the resource allocation messages.

The MAP transmitter 207 encodes and modulates the MAP information received from the MAP generator 205 in a predetermined scheme, maps the modulated MAP information to predetermined downlink resources (e.g. a front part of a frame), OFDM-modulates the mapped MAP information, upconverts the OFDM-modulated MAP information to an RF signal, and broadcasts the RF signal to the MSs through the antenna.

FIG. 3 is a block diagram of an MS according to an exemplary embodiment of the present invention. The MS includes a MAP receiver 301, a MAP interpreter 303, and a data receiver 305.

Referring to FIG. 3, the MAP receiver 301 extracts MAP data from OFDM-demodulated data of a predetermined area in a frame in the data receiver 305, demodulates and decodes the MAP data in a predetermined scheme, and provides the resulting MAP information to the MAP interpreter 303.

The MAP interpreter 303 extracts information about a resource allocation scheme and resource allocation information from the MAP information by interpreting the MAP information.

After OFDM modulation of an RF signal received from the BS, the data receiver 305 receives downlink data in slots of the frame according to the extracted information and demodulates and decodes the downlink data in a predetermined scheme.

FIG. 4 is a flowchart illustrating an operation of a BS for periodically allocating downlink resources in a wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the BS monitors whether downlink resource allocation has been requested in step 401. If the downlink resource allocation has been requested, the BS determines MSs that require downlink resource allocation and sets an MS index n to 1 in step 403.

In step 405, the BS identifies the service type of the nth MS and determines whether periodic data transmission (e.g. period=Tp) is required for the nth MS. For example, a service characterized by periodic packet generation such as VoIP can be defined as a service requiring periodic resource allocation. While a decision is made as to whether the periodic resource allocation is required according to service type, it is a mere exemplary application. Hence, the decision can be made when an MS requests periodic resource allocation. Nonetheless, the BS finally determines whether to allocate resources periodically.

When determining that the nth MS needs periodic data transmission, the BS allocates periodic resources to the nth MS in the Periodic Allocation (PA) method of an exemplary embodiment of the present invention and generates a resource allocation message to be transmitted to the nth MS in step 407. On the other hand, when determining that the nth MS does not need periodic data transmission, the BS allocates resources to the nth MS in a general resource allocation method and generates a resource allocation message to be transmitted to the nth MS in step 409.

The general resource allocation method refers to allocating resources in the form of a rectangle to an MS, starting from the first slot of a DL frame. Meanwhile, the PA method can be considered in three ways: PA based on two-dimensional absolute coordinates, PA based on time-reverse ordered slots, and PA based on frequency-axis slots.

The PA based on two-dimensional absolute coordinates is a scheme for allocating the remaining resources after general resource allocation to MSs requiring periodic resource allocation in the form of rectangles. Referring to FIG. 8, assuming that resources are allocated to MS1 in the conventional manner and periodic resources are allocated to MS2, MS3 and MS4, the BS allocates a rectangle of 24 slots in a DL frame, starting from slot #1 to MS1, two 9-slot rectangles to MS2 and MS3, respectively, and a 10-slot rectangle to MS4.

The PA based on time-reverse ordered slots allocates the remaining resources after general resource allocation to MSs requiring periodic resource allocation in a time-reverse order, that is, sequentially starting from the last slot of a DL frame. Referring to FIG. 9, assuming that resources are allocated to MS1 in the general manner and periodic resources are allocated to MS2, MS3 and MS4, the BS allocates a rectangle of 24 slots in a DL frame, starting from slot #1 to MS1. Then, stating from the last slot, the BS allocates 9 slots to MS2, 9 slots counted from the last 10th slot to MS3, and 10 slots counted from the last 19th slot to MS4. Although the periodic resources are allocated in the time-reverse order, actual packet transmission is carried out in the order of time.

The PA based on frequency-axis slots is a scheme that allocates the remaining resources after general resource allocation to MSs requiring periodic resource allocation along the frequency axis in the time-reverse order. Referring to FIG. 10, assuming that resources are allocated to MS1 in the general manner and periodic resources are allocated to MS2, MS3 and MS4, the BS allocates a rectangle of 24 slots in a DL frame, starting from slot #1 to MS1. Starting from the first slot along the frequency axis in the time-reverse order, the BS allocates 9 slots to MS2, 9 slots counted from the 10th slot to MS3, and 10 slots counted from the 19th slot to MS4. Although the periodic resources are allocated along the frequency axis, that is, lengthwise in the time-reverse order, actual packet transmission is carried out in the order of time.

According to allocation types, a resource allocation message can be configured as illustrated in Table 1 below.

TABLE 1
DL-MAP IE( ){
Allocation Type               Identifier identifying a resource
                              allocation type
if (Allocation Type==0){      General resource allocation
                              DIUC
                              CID
                              OFDMA symbol offset
                              Subchannel offset
                              NO. OFDMA symbols
                              No. subchannels
                              Repetition coding indication
}
else if (Allocation Type==1){ PA based on two-dimensional
                              absolute coordinates
                              DIUC
                              CID
                              OFDMA symbol offset
                              Subchannel offset
                              NO. OFDMA symbols
                              No. subchannels
                              Repetition coding indication
                              PA frame duration
                              PA period
}
else if (Allocation Type==2){ PA based on time-reverse ordered
                              slots
                              DIUC
                              CID
                              Duration
                              Repetition coding indication
                              PA start offset
                              PA frame duration
                              PA period
}
else if (Allocation Type==3){ PA based on frequency-axis slots
                              DIUC
                              CID
                              Duration
                              Repetition coding indication
                              PA start offset
                              PA frame duration
                              PA period
}
}

Referring to Table 1, the resource allocation message DL-MAP IE( ) of an exemplary embodiment of the present invention has a different configuration according to an allocation type. If Allocation Type is 0, it indicates the general resource allocation method. For Allocation Type 0, the resource allocation message includes Downlink Interval Usage Code (DIUC) indicating a processing scheme (e.g. a modulation and coding scheme) for a physical channel that delivers a downlink data burst, CID identifying a service and an MS, OFDMA symbol offset indicating the start of OFDMA symbols of the data burst, Subchannel Offset indicating the start of subchannels that carry the data burst, No. OFDMA symbols indicating the number of OFDMS symbols occupied for the data burst, No. Subchannels indicating the number of subchannels used for the data burst, and Repetition coding indication indicating the number of iterative codings.

If Allocation Type is 1, it indicates the PA based on two-dimensional absolute coordinates. For Allocation Type 1, the resource allocation message includes, in addition to the information included in the resource allocation message for Allocation Type=0, PA frame duration indicating the number of allocated frames and PA period indicating a period for which actual resources are allocated. If PA frame duration is 0, this means that the resource allocation ends.

Allocation Type 2 is PA based on time-reverse ordered slots and two-dimensional absolute coordinates and Allocation Type 3 is PA based on frequency-axis slots. For Allocation Type 2 and Allocation Type 3, the resource allocation message includes, in addition to DIUC, CID, and Repetition coding indication, Duration indicating the number of allocates slots, PA start offset indicating the start of the resource allocation, PA frame duration indicating the number of allocated frames, and PA period indicating a period for which actual resources are allocated. In the case of the PA based on time-reverse ordered slots, PA start offset indicates the start position of resource allocation, counted from the last slot. In the case of the PA based on frequency-axis slots, PA start offset indicates the start position of resource allocation, counted from the first slot on the frequency axis in the time reverse order.

Referring again to FIG. 4, the BS determines whether the downlink resource allocation has been completed for the MSs in step 411. If the downlink resource allocation is still going, the BS updates n to (n+1) in step 413 and returns to step 405. Upon completion of the downlink resource allocation, the BS generates MAP information using the generated resource allocation messages and broadcasts the MAP information in step 415. The BS may receive Acknowledgement (ACK) signals from the MSs.

Then the BS transmits downlink data according to the MAP information. Specifically, the BS determines whether resources have been allocated periodically or in the general manner to each of the MSs in step 417. In the case of periodic resource allocation, the BS transmits downlink data to the MS every predetermined period, for example, in slots allocated to the MS every Tp frames in step 419. That is, the BS transmits the downlink data to the MS in the predetermined resource area every predetermined period without transmitting the resource allocation message. On the other hand, in the case of general resource allocation, the BS transmits downlink data to the MS in a frame in step 421. Then the BS ends the algorithm of an exemplary embodiment of the present invention.

FIG. 5 is a flowchart illustrating an operation of an MS for receiving downlink data in a wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 5, an MS receives MAP information from a BS and determines whether downlink resources have been allocated to the MS by interpreting the MAP information in step 501.

In step 503, the MS determines whether the downlink resource allocation is periodic. In the case of periodic allocation, the MS extracts resource allocation information from the interpreted MAP information according to a resource allocation type and receives periodic downlink data in slots indicated by the extracted resource allocation information in step 505. In the case of general allocation, the MS receives downlink data in slots indicated by a resource allocation message included in the MAP information according to a general data reception method in step 507.

If the PA service is terminated for the MS, the BS reallocates the periodic resources used for the MS to another MS, thus reducing resource consumption. For example, resources are allocated to MS2, MS3 and MS4 in the PA method as illustrated in FIGS. 8, 9 and 10. Then if the periodic resource allocation ends for MS3, the BS can reallocate the periodic resources used for MS3 to MS2 and MS4 in the PA method.

If the MS temporarily discontinues the PA service, or if the BS has no more packets for the MS that receives the PA service, the BS can reallocate the periodic resources used for the MS to general MSs until the PA service of the MS resumes. This will be described below with reference to FIGS. 6 and 7.

FIG. 6 is a flowchart illustrating an operation of a BS for temporarily discontinuing and resuming PA in a wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 6, a BS determines whether PA needs to be discontinued temporarily for an MS in step 601. The BS may decide on temporary PA discontinuation when receiving a temporary PA discontinuation request from the MS or in the absence of periodic packets to be transmitted to the MS.

When deciding on temporary PA discontinuation, the BS allocates periodic resources of a frame to a general MS and generates a resource allocation message for the general MS in step 603. In step 605, the BS generates MAP information including the resource allocation message, broadcasts the MAP information to MSs, and transmits downlink data to the MSs according to the MAP information.

In step 607, the BS determines whether to resume the PA for the MS. The BS may decide on PA resumption upon receipt of a PA resumption request from the MS or upon generation of periodic packets to be transmitted to the MS.

If the BS determines not to resume the PA for the MS, the BS returns to step 603. On the other hand, when determining to resume the PA for the MS, the BS releases the periodic resources from the general MS and resumes the PA service with the periodic resources so that the MS can receive downlink data periodically without additional resource allocation in step 609. Then the BS ends the algorithm of an exemplary embodiment of the present invention.

FIG. 7 is a flowchart illustrating an operation of an MS for receiving data when PA is temporarily discontinued in a wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 7, during a service through PA, an MS receives MAP information from the BS and determines whether downlink resources have been allocated to the MS by interpreting the MAP information in step 701. The MS can request temporary service discontinuation, i.e. temporary PA discontinuation to the BS. Thus the BS can allocate the period resources of the BS to a general MS until the service resumes, generate MAP information correspondingly, and broadcast the MAP information.

In step 703, the MS determines whether the periodic resources of the MS have been allocated to another MS. If the periodic resources are still available to the MS, the MS receives periodic data in a downlink resource area allocated to the MS.

If the period resources have been allocated to another MS, the MS discontinues the periodic data reception, i.e. the service, considering that the PA is temporarily discontinued in a current frame in step 705. The MS then returns to step 701 and monitors MAP information received from the BS to determine whether the service will resume. If the MAP information does not indicate that the period resources of the MS have been allocated to another MS, the MS may determine that the PA resumes in step 707. The MS can request resumption of the service so that BS resumes the PA, generates MAP information correspondingly, and broadcasts the MAP information to MSs.

In accordance with certain exemplary embodiments of the present invention as described above, a BS broadcasts resource allocation information for the first time once for an MS to which downlink data will be transmitted periodically and then transmits the downlink data to the MS in an allocated resource area every predetermined period without broadcasting the resource allocation information for the MS in a wireless communication system. Because the BS does not need to transmit the resource allocation information to the MS every time, downlink resources can be saved from the resource allocation information. Especially for a service characterized by periodic packet generation such as VoIP, the efficiency of downlink resources can be increased.

While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

Claims

1. A method for allocating resources in a Base Station (BS) in a wireless communication system, the method comprising: allocating periodic downlink resources to Mobile Stations (MSs);generating resource allocation messages with resource allocation information for the MSs; andtransmitting control information including the resource allocation messages to the MSs.

2. The method of claim 1, wherein each of the resource allocation messages comprises at least one of an amount of resources, a start of the resources, an allocation duration, and a transmission period.

3. The method of claim 1, wherein the allocating of the periodic downlink resources comprises: selecting the MSs to receive the downlink resources periodically; andallocating the periodic downlink resources to the selected MSs based on two-dimensional absolute coordinates.

4. The method of claim 1, wherein the allocating of the periodic downlink resources comprises: selecting the MSs to receive the downlink resources periodically; andallocating the periodic downlink resources to the selected MSs in a time reverse order, starting from a last slot of a downlink frame.

5. The method of claim 1, wherein the allocating of the periodic downlink resources comprises: selecting the MSs to receive the downlink resources periodically; andallocating the periodic downlink resources to the selected MSs along a frequency axis in a time reverse order of a downlink frame.

6. The method of claim 1, wherein the MSs have requested a service characterized by periodic packet generation.

7. The method of claim 1, wherein the control information comprises MAP information.

8. The method of claim 1, further comprising transmitting downlink data to each of the MSs in a predetermined period using the allocated periodic downlink resources.

9. The method of claim 1, further comprising, when the periodic downlink resource allocation ends for an MS among the MSs, reallocating periodic downlink resources used for the MS to the other MSs.

10. The method of claim 1, further comprising, when the periodic downlink resource allocation ends or is temporarily discontinued for an MS among the MSs, reallocating periodic downlink resources used for the MS to another MS.

11. The method of claim 10, further comprising ending or temporarily discontinuing the periodic downlink resource allocation for the MS, upon receipt of a request for temporarily discontinuing the periodic downlink resource allocation from the MS.

12. The method of claim 10, further comprising, when the ended or temporarily discontinued periodic downlink resource allocation resumes, discontinuing allocation of the periodic resources to the another MS.

13. The method of claim 12, further comprising resuming the periodic downlink resource allocation for the MS, upon receipt of a request for resuming the periodic downlink resource allocation from the MS.

14. The method of claim 10, wherein a resource allocation message transmitted to the another MS comprises at least one of an amount of resources and a start of the resources.

15. A method for receiving data in a Mobile Station (MS) in a wireless communication system, the method comprising: receiving and interpreting control information from a Base Station (BS); andreceiving downlink data using downlink resources allocated to the MS with a predetermined period, when the downlink resources are allocated periodically.

16. The method of claim 15, wherein the control information comprises MAP information.

17. The method of claim 15, wherein the control information comprises a resource allocation message with resource allocation information for the MS.

18. The method of claim 17, wherein the resource allocation message comprises at least one of an amount of resources, a start of the resources, an allocation duration, and a transmission period.

19. The method of claim 15, further comprising transmitting a request for temporarily discontinuing the periodic downlink resource allocation to the BS, when a service to which the periodic downlink resources are allocated is temporarily discontinued.

20. The method of claim 19, further comprising transmitting a request for resuming the periodic downlink resource allocation to the BS, when the temporarily discontinued service resumes.

21. An apparatus for allocating resources in a Base Station (BS) in a wireless communication system, comprising: a resource allocator for allocating periodic downlink resources to Mobile Stations (MSs); anda control information generator for generating resource allocation messages with resource allocation information for the MSs, and for generating control information including the resource allocation messages.

22. The apparatus of claim 21, further comprising: a data transmitter for transmitting downlink data to the MSs using the allocated periodic downlink resources in a predetermined period; anda control information transmitter for transmitting the control information to the MSs.

23. The apparatus of claim 21, wherein the resource allocator allocates the periodic downlink resources to the MSs, when the MSs request a service characterized by periodic packet generation.

24. The apparatus of claim 21, wherein each of the resource allocation messages comprises at least one of an amount of resources, a start of the resources, an allocation duration, and a transmission period.

25. The apparatus of claim 21, wherein the resource allocator allocates the periodic downlink resources to the MSs based on two-dimensional absolute coordinates.

26. The apparatus of claim 21, wherein the resource allocator allocates the periodic downlink resources to the MSs, in a time reverse order, starting from a last slot of a downlink frame.

27. The apparatus of claim 21, wherein the resource allocator allocates the periodic downlink resources to the MSs, along a frequency axis in a time reverse order of a downlink frame.

28. The apparatus of claim 21, wherein the control information comprises MAP information.

29. The apparatus of claim 21, wherein when the periodic downlink resource allocation ends for an MS among the MSs, the resource allocator reallocates periodic downlink resources used for the MS to the other MSs.

30. The apparatus of claim 21, wherein when the periodic downlink resource allocation ends or temporarily is discontinued for an MS among the MSs, the resource allocator reallocates periodic downlink resources used for the MS to another MS.

31. The apparatus of claim 30, wherein a resource allocation message transmitted to the another MS comprises at least one of the amount of resources and the start of the resources.

32. The apparatus of claim 30, wherein upon receipt of a request for temporarily discontinuing the periodic downlink resource allocation from the MS, the resource allocator ends or temporarily discontinues the periodic downlink resources for the MS.

33. The apparatus of claim 30, wherein when the ended or temporarily discontinued periodic downlink resource allocation resumes, the resource allocator discontinues allocation of the periodic resources to the another MS.

34. The apparatus of claim 33, wherein upon receipt of a request for resuming the periodic downlink resource allocation from the MS, the resource allocator resumes the periodic downlink resource allocation for the MS.

35. An apparatus for receiving data in a Mobile Station (MS) in a wireless communication system, comprising: a control information interpreter for interpreting control information received from a Base Station (BS); anda data receiver for, when downlink resources are allocated periodically to the MS, receiving downlink data using the allocated downlink resources with a predetermined period.

36. The apparatus of claim 35, wherein the control information comprises MAP information.

37. The apparatus of claim 35, wherein the control information comprises a resource allocation message with resource allocation information for the MS.

38. The apparatus of claim 37, wherein the resource allocation message comprises at least one of an amount of resources, a start of the resources, an allocation duration, and a transmission period.

39. The apparatus of claim 35, further comprising a control information receiver for receiving the control information from the BS.

40. The apparatus of claim 35, further comprising a transmitter for transmitting a request for temporarily discontinuing the periodic downlink resource allocation to the BS, when a service to which the periodic downlink resources are allocated is temporarily discontinued.

41. The apparatus of claim 40, wherein when the temporarily discontinued service resumes, the transmitter transmits a request for resuming the periodic downlink resource allocation to the BS.

42. A method for allocating resources in a Base Station (BS) in a wireless communication system, the method comprising: generating periodically resource allocation messages with resource allocation information for MSs; andtransmitting control information including the resource allocation messages to the MSs.

43. An apparatus for allocating resources in a Base Station (BS) in a wireless communication system, the apparatus comprising: means for generating periodically resource allocation messages with resource allocation information for MSs; andmeans for transmitting control information including the resource allocation messages to the MSs.

44. A method for receiving data in a Mobile Station (MS) in a wireless communication system, the method comprising: receiving control information from a Base Station (BS); andreceiving downlink data using downlink resources periodically allocated to the MS.

45. An apparatus for receiving data in a Mobile Station (MS) in a wireless communication system, the method comprising: means for receiving control information from a Base Station (BS); andmeans for receiving downlink data using downlink resources periodically allocated to the MS.