Optimized signalling of scheduling decisions

Information

  • Patent Application
  • 20070258373
  • Publication Number
    20070258373
  • Date Filed
    July 10, 2006
    18 years ago
  • Date Published
    November 08, 2007
    17 years ago
Abstract
A method, terminal device, network element, and computer program product for signalling a scheduling information used for indicating resource allocation states of a plurality of available resource blocks to a plurality of scheduled devices are disclosed, wherein a resource allocation state is set for each of the available resource blocks and multiplied by the number of possible allocation states to the power of a sequential number of the resource block. Then, the multiplication results of all available resource blocks are summed and the summing result is transmitted to the plurality of scheduled devices. Thereby, the required amount of signalling bits can be reduced considerably, while still maintaining the same signalling content.
Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described based on an embodiment with reference to the accompanying drawings in which:



FIG. 1 shows a schematic diagram indicating a network architecture in which the invention, in an exemplary embodiment, can be implemented;



FIG. 2 shows a schematic illustration of channel-dependent scheduling and link adaptation in time and frequency domain;



FIG. 3 shows a single-layer allocation table on which one embodiment is based; and



FIG. 4 shows schematic block diagrams of a network element and terminal device according to an embodiment of the invention.





DESCRIPTION OF THE EMBODIMENT

In the following, an embodiment of the invention will be described based on a channel-dependent scheduling and link adaptation (rate and/or power control) in time and frequency domain, where a scheduler function or unit assigns a number of resource blocks, e.g., frequency resource blocks, to a user.



FIG. 1 shows a schematic diagram of a general network architecture in which the invention, in an exemplary embodiment, can be implemented. A radio access network 300, e.g., a Universal Mobile Telecommunications System (UMTS) Terrestrial Access Network (UTRAN) or a Wireless Local Area Network (WLAN), provide access to a UE 10 via an access device (20), e.g., a base station device or an access point, having a scheduler functionality for scheduling resources by allocating the frequency resource blocks to users which are currently connected to the access network 300. Allocation or scheduling decisions are signaled to the users by a scheduling information 400 transmitted to the connected users.


An efficient method of signalling the above scheduling information is provided as an optimum solution for any number of user allocations. The essence of the new signalling approach is to compress the user signal space such that the total required number of signalling bits will become ceil(M*log 2(N+1)). Compared to the initially discussed signalling approach which provides a total required signalling bit number of M*ceil(log 2(N+1)) as the signalling need, signalling savings can be achieved by moving the “ceil” function field, e.g., in the case of 24 available frequency resource blocks (M=24) and 4 allocated users (N=4), 22% in signalling overhead can be saved. In the case of 12 available frequency resource blocks (M=12) and 8 allocated users (N=8), 19% in signalling overhead can be saved.


The exemplary embodiment starts from the fact that the EEI and RTI fields of FIG. 3 are not orthogonal. Two bits are used per resource block (one for EEI and one for RTI). However, as these two bits can represent 4 states, and actually only 3 states are needed, there is room for compressing this information in an efficient way.


In one embodiment, the compressing or encoding of the scheduling decisions or information is based on the following general equation:









T
=




k
=
0


M
-
1





S
k

·

R
k







(
1
)







wherein T denotes the compressed scheduling information or total state to be signalled to the scheduled devices (users), Sk denotes the resource allocation state which is selected from the values 0, 1, . . . , N−1, R denotes the number of possible resource allocation states, M denotes the available number of resource blocks (frequency resource blocks), and k denotes the sequential number of the resource block, starting from index ‘0’.


Applied to the specific example of the fixed part 101 of the allocation information table of FIG. 3, the proposed signalling or encoding approach according to equation (1) can be used to compress the user signal space such that the total required number of signalling bits will become ceil(M*log 2(3)), where M is the number of resource blocks (frequency resource blocks) for the system bandwidth. Following this approach, the signalling need for this fixed field allocation would be reduced as follows:


In the case of M=24, only 39 bits are required for signalling the EEI and RTI bits, compared to 48 bits of the conventional allocation table at a system bandwidth of 10 MHz. In the case of M=48, only 77 bits are required for signalling the EEI and RTI bits, compared to 96 bits of the conventional allocation table at a system bandwidth of 20 MHz.


The resource allocation states can be defined and set, such that the following state values are valid (the naming and order of the states is not important to the principle):


State 0: Resource not allocated for the current sub-frame
State 1: Resource allocated and used for localized transmission.
State 2: Resource allocated and used for distributed transmission.

Following equation (1), the allocation state for resource block ‘k’ can be obtained as follows:






S
k
=x
k·3k,  (2)


where xk can take the values {0,1,2} depending on the state of the kth resource block.


Referring again to equation (1), the total state T can be defined as the sum of the allocation states (and decoded correspondingly). I.e., the transmitted scheduling information of the EEI and RTI bits of the fixed part 101 of FIG. 3 can be compressed or encoded to:






T=sum(Sk)  (3)


over the values of the sequential number ‘k’ of the resource block, where k=24 for a system bandwidth of 10 MHz, and k=48 for a system bandwidth of 20 MHz.


Similarly, it is possible to define a decoding algorithm, which will decode the state information. However, as there is a tradition of specifying the encoding of data rather than the decoding, the above algorithm should be sufficient for the skilled person to derive the encoding algorithm.



FIG. 4 shows a schematic block diagram of a transmission system based on FIG. 1, wherein the access device 20 comprises an encoder or encoding function or unit 200, to which the allocation table of FIG. 3 with the fixed part 101 and variable part 102 is supplied. Based on the above equations (2) and (3), the encoding unit 200 generates a compressed scheduling information 103, which corresponds to the above total state T and comprises the content of the fixed part 101. This compressed scheduling information 103 is transmitted to the scheduled units, e.g. the UE 10, as a bit sequence together with variable part 102. The UE 10 comprises a decoder or decoding function or unit 100, which receives the compressed scheduling information 103 with the variable part 102 and applies a decoding processing to retrieve the original allocation table with the original fixed part 101.


By transmitting the compressed scheduling information 103 instead of the original fixed part 101, a significant reduction of signalling bits can be achieved.


In summary, a method, terminal device, network element, and computer program product for signalling a scheduling information used for indicating resource allocation states of a plurality of available resource blocks to a plurality of scheduled devices have been described, wherein a resource allocation state is set for each of the available resource blocks and multiplied by the number of possible allocation states to the power of a sequential number of the resource block. Then, the multiplication results of all available resource blocks are summed and the summing result is transmitted to the plurality of scheduled devices. Thereby, the required amount of signalling bits can be reduced considerably, while still maintaining the same signalling information content.


The above processing steps described above and performed by the encoder 200 of the access device 20 of FIG. 4 may be implemented as concrete hardware entities or units, or alternatively may be based on software routines controlling data processors or computer devices provided in the access device 20. The same applies to the respective decoding steps performed at the decoding unit 100 of the terminal device 10 of FIG. 4. Consequently, one embodiment of the invention may be implemented as a computer program product comprising code means for generating each individual step of the encoding or decoding procedure according to the embodiment when run on a computer device or data processor of the access device 20 or terminal device 10, respectively.


It is apparent that the invention can easily be extended to the multi-layer domain, since it relates to the content of the fixed length part. In the multi-layer domain, the layer may represent the spatial dimension. For example, in a transmission using multiple antennas, the time-frequency resource defined by the frequency resource block may be re-used by spatial multiplexing.


The described embodiments are related to signalling of frequency domain packet scheduling decisions. However, the invention, according to various embodiments, can be applied whenever efficient signalling for any kind of scheduling information is needed. Exemplary embodiments may thus vary within the scope of the attached claims.

Claims
  • 1. A method of signalling a scheduling information used for indicating resource allocation states of a plurality of available resource blocks to a plurality of scheduled devices, said method comprising: setting a resource allocation state for each of said available resource blocks;multiplying a value of a resource allocation state of a resource block by the number of possible allocation states to the power of a sequential number of said resource block, said sequential number starting from the value “0”;performing the step of multiplying for all available resource blocks;summing all multiplication results; andtransmitting the summing result to said plurality of scheduled devices.
  • 2. A method according to claim 1, wherein said number of possible resource allocation states is 3.
  • 3. A method according to claim 1, wherein said value of said resource allocation state is selected from the values 0, 1, and 2.
  • 4. A method according to claim 1, wherein said possible resource allocation states comprise a first state indicating that a related resource block has not been allocated to a user, a second state indicating that the related resource block has been allocated to a user and is used for localized transmission, and a third state indicating that the related resource block has been allocated to a user and is used for distributed transmission.
  • 5. A method according to claim 1, wherein said resource block is a frequency resource block of an orthogonal frequency division multiplexing system.
  • 6. A method according to claim 1, wherein said scheduling information is used to compress a fixed-length part of an allocation table.
  • 7. A method according to claim 6, wherein said fixed length part comprises a set of resource block type indicator bits and a set of entry existence indicator bits.
  • 8. A network element for signalling a scheduling information used for indicating resource allocation states of a plurality of available resource blocks to a plurality of scheduled devices, said network element comprising encoding means configured: to set a resource allocation state for each of said available resource blocks;to multiply a value of a resource allocation state of a resource block (50) by the number of possible allocation states to the power of a sequential number of said resource block, said sequential number starting from the value “0”;to perform the step of multiplying for all available resource blocks;to sum all multiplication results; andto transmit the summing result to said plurality of scheduled devices.
  • 9. A network element according to claim 8, wherein said number of possible resource allocation states is 3.
  • 10. A network element according to claim 8, wherein said network element is configured to select said value of said resource allocation state from the values 0, 1, and 2.
  • 11. A network element according to claim 8, wherein said network element is configured set said resource allocation states to one of a first state indicating that a related resource block has not been allocated to a user, a second state indicating that the related resource block has been allocated to a user and is used for localized transmission, and a third state indicating that the related resource block has been allocated to a user and is used for distributed transmission.
  • 12. A network element according to claim 8, wherein said resource block is a frequency resource block of an orthogonal frequency division multiplexing system.
  • 13. A network element according to claim 8, wherein said network element is configured to use said scheduling information to compress a fixed-length part of an allocation table.
  • 14. A network element according to claim 13, wherein said fixed length part comprises a set of resource block type indicator bits and a set of entry existence indicator bits.
  • 15. A terminal device comprising decoding means for decoding a scheduling information signaled by a method according to claim 1.
  • 16. A computer program product comprising code means for generating the steps of method claim 1 when run on a computer device.
  • 17. A system for signalling a scheduling information for indicating resource allocation states of a plurality of available resource blocks to a plurality of scheduled devices, said system comprising a network element according to claim 8, and a terminal device according to claim 15.
Priority Claims (1)
Number Date Country Kind
EP 06 009 473.7 May 2006 EP regional