Method and transmitter for allocating resources to terminal in telecommunication system

10873943 ยท 2020-12-22

Assignee

Inventors

Cpc classification

International classification

Abstract

The invention relates to allocating resources in a carrier when several subcarrier spacing configurations coexists, and more particularly to avoid or at least reduce the loss of resources when introducing guard bands to avoid inter-numerology interferences. The invention proposes to start the allocation of resource blocks to a terminal on a different subcarrier than the first subcarrier. Therefore the invention proposes a method to allocate such resource blocks to a terminal.

Claims

1. A method for allocating resources to a terminal in a telecommunication system comprising at least a carrier comprising several subcarriers, said carrier supporting at least one subcarrier spacing configuration Afo and one subcarrier spacing configuration f.sub.1, with f.sub.1=q.Math.f.sub.0, q being a strictly positive integer, said method comprising: a) selecting the subcarrier spacing configuration f.sub.1; b) determining a number L of resource blocks having subcarriers of said subcarrier spacing configuration f.sub.1; c) allocating to said terminal subcarriers among the subcarriers of the carrier of subcarrier spacing configurations f.sub.1, having their frequencies: greater or equal to a frequency, namely f.sub.start, being the lowest frequency among frequencies of subcarriers of subcarrier spacing configuration f.sub.1 having a frequency higher than or equal to f.sub.ref+m.Math.N.Math.f.sub.1+k.Math.N.Math.f.sub.0, f.sub.ref being the lowest frequency among the subcarriers that are allowable for subcarrier spacing f.sub.1 in the carrier, k being an integer greater or equal to 1 and lesser or equal to (q1), N being the number of subcarriers in a resource block, m being an integer greater or equal to 0 and lesser than a maximum number of resource blocks, allowable in the carrier, having subcarriers of subcarrier spacing configuration f.sub.1; lesser or equal to a frequency f.sub.ref+m.Math.N.Math.f.sub.1+(L.Math.N1).Math.f.sub.1, namely f.sub.last, wherein k is determined such as f.sub.startf.sub.near is greater than G, G being a strictly positive threshold, and f.sub.near being a frequency of a subcarrier with a subcarrier spacing configuration different from f.sub.1, said subcarrier having the highest frequency among frequencies of subcarriers allocated in the carrier having subcarrier spacing configurations different from f.sub.1 and having lower frequencies than f.sub.ref+(m+1).Math.N.Math.f.sub.1.

2. The method according to claim 1, wherein m is determined such as at least one subcarrier of subcarrier spacing configurations f.sub.1, having a frequency of at least f.sub.ref+m.Math.N.Math.f.sub.1 and at the most f.sub.ref+(m+1).Math.N.Math.f.sub.1f.sub.1, can be allocated to the terminal.

3. The method according to claim 1, wherein the subcarrier spacing configuration f.sub.0 is the smallest subcarrier spacing configuration among the subcarrier spacing configuration supported by the carrier.

4. The method according to claim 1, wherein said number L, L1, satisfies to:
q.Math.L+NRB.sub.start.sup.(0)N.sub.RB.sup.(0) where: N.sub.RB.sup.(0) is a maximum number of resource blocks comprising N subcarriers of the subcarrier spacing configuration f.sub.0 that are allowable in said carrier, NRB.sub.start.sup.(0) is a maximum number of resource blocks comprising N subcarriers of the subcarrier spacing configuration f.sub.0 that are allowable in said carrier, said resource blocks having their subcarriers frequencies lower than said frequency f.sub.start.

5. The method according to claim 4, further comprising sending to said terminal allocation information based on the subcarriers allocated to the terminal.

6. The method according to claim 5, wherein the allocation information based on the subcarriers allocated to the terminal, is a resource indication value, RIV, which is an integer and a function of L and NRB.sub.start.sup.(0).

7. The method according to claim 6, wherein said RIV function is an injective function of any couple comprising L and NRB.sub.start.sup.(0) values.

8. The method according to claim 6, wherein said RIV is a surjective function among the integers from 0 to the maximum value taken by RIV.

9. The method according to claim 6, wherein said RIV is defined by: { RIV = ( L - 1 ) ( r 1 + 1 + .Math. ( p 1 - 1 ) * q 2 .Math. + 1 ) + NRB start ( 0 ) if NRB start ( 0 ) r 1 + 1 + .Math. ( p 1 - 1 ) * q 2 .Math. RIV = ( p 1 - L ) * ( r 1 + 1 + .Math. ( p 1 - 1 ) * q 2 .Math. + 1 ) + ( r 1 + 1 + N RB ( 0 ) - q - NRB start ( 0 ) ) otherwise where: r.sub.1 is a remainder of the division of N.sub.RB.sup.(0) by q p 1 = .Math. N RB ( 0 ) q .Math. .

10. The method according to claim 6, wherein said RIV is defined by: { RIV = ( L - 1 ) ( N RB ( 0 ) - q + r 1 + 2 ) + NRB start ( 0 ) if L .Math. p 1 / 2 .Math. RIV = ( p 1 - L ) * ( N RB ( 0 ) - q + r 1 + 2 ) + ( N RB ( 0 ) - q + r 1 + 1 - NRB start ( 0 ) ) otherwise where: r.sub.1 is a remainder of the division of N.sub.RB.sup.(0) by q p 1 = .Math. N RB ( 0 ) q .Math. .

11. The method according to claim 6, wherein said RIV is defined by: RIV = ( .Math. l = 1 L - 1 S l ) + NRB start ( 0 ) = ( L - 1 ) * ( N RB ( 0 ) + 1 ) - q * L * ( L - 1 ) 2 + NRB start ( 0 ) where:
S.sub.l=N.sub.RB.sup.(0)q*l+1.

12. The method according to claim 1, wherein said RIV is defined by: { RIV = ( L - 1 ) + p 1 * NRB start ( 0 ) if NRB start ( 0 ) r 1 + 1 + .Math. 1 2 * q * ( p 1 - 1 ) .Math. RIV = p 1 * ( r 1 + 1 + N RB ( 0 ) - q - NRB start ( 0 ) ) + otherwise p 1 - L where: r.sub.1 is a remainder of the division of N.sub.RB.sup.(0) by q p 1 = .Math. N RB ( 0 ) q .Math. .

13. A non-transitory computer-readable medium having stored there on a computer program product comprising code instructions to perform the method according to claim 1, when said instructions are run by a processor.

14. A transmitter comprising a processor for allocating resources to a terminal in a telecommunication system comprising at least a carrier comprising several subcarriers, said carrier supporting at least one subcarrier spacing configuration f.sub.0 and one subcarrier spacing configuration f.sub.1, with f.sub.1=q.Math.f.sub.0, q being a strictly positive integer, said transmitter being configured to perform: a) selecting the subcarrier spacing configuration f.sub.1; b) determining a number L of resource blocks having subcarriers of said subcarrier spacing configuration f.sub.1; c) allocating to said terminal subcarriers among the subcarriers of the carrier of subcarrier spacing configurations f.sub.1, having their frequencies: greater or equal to a frequency, namely f.sub.start, being the lowest frequency among frequencies of subcarriers of subcarrier spacing configuration f.sub.1 having a frequency higher than or equal to f.sub.ref+m.Math.N.Math.f.sub.1+k.Math.N.Math.f.sub.0, f.sub.ref being the lowest frequency among the subcarriers that are allowable for subcarrier spacing f.sub.1 in the carrier, k being an integer greater or equal to 1 and lesser or equal to (q1), N being the number of subcarriers in a resource block, m being an integer greater or equal to 0 and lesser than a maximum number of resource block, allowable in the carrier, having subcarriers of subcarrier spacing configuration f.sub.1; lesser or equal to a frequency f.sub.ref+m.Math.N.Math.f.sub.1+(L.Math.N1).Math.f.sub.1, namely f.sub.last, wherein k is determined such as f.sub.startf.sub.near is greater than G, G being a strictly positive threshold, and f.sub.near being a frequency of a subcarrier with a subcarrier spacing configuration different from f.sub.1, said subcarrier having the highest frequency among frequencies of subcarriers allocated in the carrier having subcarrier spacing configurations different from f.sub.1 and having lower frequencies than f.sub.ref+(m+1).Math.N.Math.f.sub.1.

15. A transmitter according to claim 14, comprising a memory unit storing, for each couple of possible values of a number NRB.sub.start.sup.(0) and said L a unique resource indication value RIV, NRB.sub.start.sup.(0) being a maximum number of resource blocks comprising N subcarriers of the subcarrier spacing configuration f.sub.0 that are allowable in said carrier, said resource blocks having their subcarriers frequencies lower than said frequency f.sub.start, and wherein said transmitter is further configured to: provide a RIV value based on a couple of L and NRB.sub.start.sup.(0) corresponding to the allocation of subcarriers performed by the transmitter, and transmit the RIV to the terminal.

16. A terminal, in a telecommunication system, comprising a processor to use allocated resources in a carrier, said resources having been allocated according to claim 1, comprises: a communication module configured to receive an allocation resource block information through a control channel, a processing module which is configured to determine the subcarriers that are allocated to said terminal according to the allocation resource block information, wherein the processing module is configured to determine said subcarriers of subcarrier spacing configurations f.sub.1 allocated to the terminal: as having their frequencies greater or equal to f.sub.start, and as having their frequencies lesser or equal to f.sub.last.

17. A terminal according to claim 16, wherein said terminal further comprises a memory unit storing for each couple of possible values of a number NRB.sub.start.sup.(0) and said L a unique resource indication value RIV, NRB.sub.start.sup.(0) being a maximum number of resource blocks comprising N subcarriers of the first subcarrier spacing configuration f.sub.0 that are allowable in said carrier, said resource blocks having their subcarriers frequencies lower than said frequency f.sub.start, and wherein said processing module is configured to read said memory unit and determine the couple values L and NRB.sub.start.sup.(0) and recover f.sub.start and f.sub.last, upon reception of an RIV value in said allocation resource block information.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a transmitter and a terminal to which resources are allocated.

(2) FIG. 2A schematizes a usual resource block scheduling in a carrier where only one numerology is defined.

(3) FIG. 2B schematizes a usual resource block scheduling in a carrier where several subcarrier spacing configurations coexists usually.

(4) FIG. 2C schematizes resource block scheduling according to the invention in a carrier where several subcarrier spacing configurations coexists.

(5) FIG. 3A illustrates a flowchart representing the steps to transmit resource allocation information.

(6) FIG. 3B illustrates a flowchart representing the steps of receiving by the terminal the resource allocation information and decoding this information to define the resource blocks allocated to the terminal.

DESCRIPTION OF EMBODIMENTS

(7) Referring to FIG. 1, there is shown a transmitter 1, for example in the OFDM-based 5G system like NR, a base station BS and a terminal in the cell of the transmitter. The terminal 2, for example in the OFDM-based 5G system like NR a user equipment UE, is allocated resources by the base station.

(8) The transmitter 1 comprises one communication module (COM_trans) 3, one processing module (PROC_trans) 4 and a memory unit (MEMO_trans) 5. The MEMO_trans 5 comprises a non-volatile unit which retrieves the computer program and a volatile unit which retrieves the allocation parameters. The PROC_trans which is configured to determine the resource allocation information, such as a RIV value, according to the resource blocks that are allocated to the terminal. The COM_trans is configured to transmit to the terminal the resource allocation information.

(9) The terminal comprises one communication module (COM_term) 6, one processing module (PROC_term) 7 and a memory unit (MEMO_term) 8. The MEMO_term 8 comprises a non-volatile unit which retrieves the computer program and a volatile unit which retrieves the parameters of the carrier and the resource allocation information. The PROC_term 7 is configured to determine the subcarriers that are allocated to the terminal according to the resource allocation information. The COM_term 6 is configured to receive from the transmitter a resource allocation information.

(10) In the following, only part of the carrier band or part of a pre-defined portion of the carrier band is represented.

(11) Referring to FIG. 2A, there is shown part of a carrier where only one numerology is defined and where resource blocks from this numerology are scheduled. The boxes represent resource blocks containing 12 subcarriers in the frequency domain across a fixed number of OFDM symbols in the time domain. For example in LTE a carrier may have a bandwidth of 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, or 20 MHz. Around 90% of this bandwidth is effectively used for the communication needs. In the frequency domain, groups of subcarriers are allocated to a terminal in the resource allocation process. In the LTE/LTE-Advanced subcarriers are grouped into resource blocks (RB) of 12 subcarriers each. The resource block defines the resource allocation granularity, in the sense where a user is allocated a certain number of resource blocks, and therefore a certain bandwidth. In the LTE/LTE-Advanced the subcarrier spacing, that is the frequency spacing between two adjacent subcarrier, is fixed to 15 kHz. Therefore the frequency bandwidth of a resource block is fixed and the possible number of resource blocks in a carrier is only dependent on the carrier bandwidth.

(12) To a numerology and more specifically to a subcarrier spacing configuration corresponds a raster, in which the socket of the raster corresponds to the size of a resource block of the same numerology in the frequency domain. All the resource blocks are scheduled aligned on this raster. Each potential resource block aligned on the raster is indexed to an integer number. For example in the logical region each of the N.sub.RB virtual resource blocks is numbered from 0 to N.sub.RB1. Several scheme of allocation exist, for example in LTE/LTE-A resource allocation type 2 is a compact format indicating to a terminal a set of contiguously virtual resource blocks which are allocated to it for downlink or uplink transfer. Therefore a resource indication value (RIV) corresponding to the number NRB.sub.start of the first contiguous resource block RB.sub.start allocated to the terminal and a length L in terms of virtually contiguously allocated resource blocks, is sent to the terminal. The RIV may be defined by:
RIV=N.sub.RB(L1)+NRB.sub.start if (L1)N/2,
RIV=N.sub.RB(N.sub.RBL+1)+(N.sub.RB1NRB.sub.start), otherwise.
Where NRB.sub.start is the number corresponding to the position of RB.sub.start.

(13) The RIV value enables the terminal to decode the position of the first virtual resource block RB.sub.start which is allocated to it and the number of virtually contiguous resource blocks that are allocated to the terminal. Once RB.sub.start and L are decoded the terminal is able to define the resource blocks that where allocated to it. In the example of FIG. 2A, L is equal to 3 and only 3 resource blocks are allocated, the potential resource blocks are materialized by dotted line squares.

(14) Referring to FIG. 2B, there is shown part of a carrier where several subcarrier spacing configurations coexists and where resource blocks from three of these different numerologies are scheduled. This is especially possible in a OFDM-based 5G system like NR (New Radio) standard. For example in the FIG. 2B, three subcarrier spacing configurations coexists which are f.sub.0, f.sub.1 and f.sub.2. BW is the effectively occupied bandwidth of the carrier. The maximum number of resource blocks of a specific numerology that are allowable in the carrier is

(15) N RB ( i ) = .Math. BW f i .Math. .
It should be noted that for certain subcarrier spacing configurations one extra RB can exist if fractional RBs containing less than N subcarriers are allowed for example at band edge. For the numerical example {f.sub.0, f.sub.1, f.sub.2}={kHz, 30 kHz, 60 kHz} and with N=12 subcarriers per resource block. The boxes represent resource blocks containing 12 subcarriers in the frequency domain FIG. 2B shows a scheduling of resource blocks in three different subcarrier spacing configurations. Boxes of one rectangle and with fine outlines represent resource blocks of subcarrier spacing configuration f.sub.0, boxes of two rectangles and with medium outlines represent resource blocks of subcarrier spacing configuration f.sub.1 and boxes of four rectangles and with thick outlines represent resource blocks of subcarrier spacing configuration f.sub.2. Each resource block is aligned on its raster. Therefore, the first subcarrier of each resource block is on the raster of the corresponding subcarrier spacing configuration. All the subcarriers of the resource block are then allocated to a same terminal. If the allocation is compact, then the L contiguous resource blocks are allocated to the same terminal, that is all the subcarriers starting from the first subcarrier of the first resource block to the last subcarrier of the L.sup.th resource block are allocated to the same terminal.

(16) Like mentioned above, between two subcarriers of different subcarrier spacing configurations, equally to resource blocks of different subcarrier spacing configurations a guard band (represented on FIG. 2B and FIG. 2C by the shaded areas) is necessary to avoid interference inter-numerology. Indeed, two subcarriers of the same subcarrier spacing configuration are spaced to respect an orthogonality property, that is the sinc-shaped subcarrier spectra exhibit zero-crossings at all the positions of the other subcarriers with a same subcarrier spacing. On the contrary, the sinc-shaped spectra of subcarriers with a given subcarrier spacing do not exhibit zero crossings at all the positions of subcarriers with a different subcarrier spacing, which engenders inter-numerology interference.

(17) For this reason it is necessary to include a guard band between two resource block of two different numerologies. As shown in FIG. 2B, guard bands are included through the scheduling process, that is by avoiding allocating a resource block contiguously to another resource block when their numerologies are different. By doing so when scheduling resource blocks of a high subcarrier spacing configuration like f.sub.2, aligned on their raster, important loss of resources in the carrier can occur. This can be seen in FIG. 2B by the gap imposed between the third scheduled resource block of subcarrier spacing configuration f.sub.1 and the first resource block of subcarrier spacing configuration like f.sub.2 scheduled, this gap, is at least the size of a resource block of subcarrier spacing configuration f.sub.1 and can even be the size of a resource block of subcarrier spacing configuration f.sub.2, if no more resource blocks of subcarrier spacing configuration f.sub.1 is left to schedule to reduce this gap, which is beyond what is necessary to avoid interference inter-numerology.

(18) For the simplicity of the expose, in FIG. 2B and FIG. 2C only the cases where all the reference frequency of each numerology are the same are depicted.

(19) Referring to FIG. 2C, as in the example of FIG. 2B there is shown part of a carrier where several subcarrier spacing configurations coexist and where resource blocks from three of these different numerologies are scheduled. In contrary to FIG. 2B, the first subcarrier of each resource allocation of a subcarrier spacing configuration can be different from the first subcarrier of a resource block of the same subcarrier spacing configuration, aligned on its raster. This enables to set guard bands in a flexible manner, thus avoiding unnecessary large guard band to prevent inter-numerology interference. Indeed, in FIG. 2C, the first subcarrier of the resource allocation (namely SC.sub.start) of subcarrier spacing configuration f.sub.2 is on the raster of the subcarrier spacing configuration f.sub.0 at N.Math.f.sub.0 from the first subcarrier (namely SC.sub.first) of the potential resource block of subcarrier spacing configuration f.sub.2, aligned on its raster, to which the first subcarrier of the resource allocation belongs. Thus the subcarriers of subcarrier spacing configuration f.sub.2 between the first subcarrier of said potential resource block and the first subcarrier of the resource allocation are not allocated. Only the fourth subcarrier of said potential resource block and the following subcarriers are allocated. The following subcarriers of this resource allocation are allocated in respect to the raster, that is, the last subcarrier of such a resource allocation is the last subcarrier of a resource block of a subcarrier spacing configuration f.sub.2.

(20) The situation is similar between the last subcarrier of the resource allocation of subcarrier spacing configuration f.sub.2 and the following subcarrier of subcarrier spacing configuration f.sub.1.

(21) More specifically the first subcarrier of the resource allocation of subcarriers of subcarrier spacing configuration f.sub.2 is made according to the raster of subcarrier spacing configuration f.sub.0. This enables to set the size of the guard band with a scale of N.Math.f.sub.0, which is more flexible than a scale of N.Math.f.sub.2. Therefore, the transmitter can determine a guard band of N.Math.f.sub.0, 2.Math.N.Math.f.sub.0 or 3.Math.N.Math.f.sub.0. It is important to notice that when a guard band is set, for instance k.Math.N.Math.f.sub.0, it is possible that no subcarrier of the subcarrier spacing configuration f.sub.2 exist at k.Math.N.Math.f.sub.0, this is the case when q.sub.2, such as f.sub.2=q.sub.2.Math.f.sub.0, is not a divisor of N. In this case the SC.sub.start of the resource allocation is the first subcarrier of the subcarrier spacing configuration f.sub.2 after the guard band.

(22) To allocate such a resource allocation the transmitter defines the number NRB.sub.start.sup.(0) of resource blocks of subcarrier spacing configuration f.sub.0 containing subcarriers with frequencies lower than the frequency of the end of the guard band. In addition the transmitter defines the number L, L1 corresponding to the resource block of subcarrier spacing configuration f.sub.2 (L.sup.(2) on FIG. 2C) allocated contiguously and in addition to the uncompleted resource block starting with SC.sub.start.

(23) Therefore a specific RIV is defined as a function of L and NRB.sub.start.sup.(0).

(24) For example:

(25) { RIV = ( L - 1 ) + p 2 * NRB start ( 0 ) if NRB start ( 0 ) r 2 + 1 + .Math. 2 .Math. p 2 - 2 .Math. RIV = .Math. N RB ( 0 ) 4 .Math. * ( r 2 + N RB ( 0 ) - 3 - NRB start ( 0 ) ) + otherwise p 2 - L
Where r.sub.2 is the remainder of the division of N.sub.RB.sup.(0) by q.sub.2 (In the example of FIG. 3, q.sub.2=f.sub.2/f.sub.0=4).

(26) Referring to FIG. 3A there is shown a flowchart representing the steps according to an aspect of the invention, to allocate subcarriers of subcarrier spacing configuration in the carrier by the transmitter to a terminal.

(27) At step S11 the transmitter sends to the terminal parameters concerning the cell settings including the carrier bandwidth BW and information on supported numerologies. More specifically the transmitter sends to the terminal information allowing the terminal to know directly or deduce at least the following parameters: f.sub.0, f.sub.2, N.sub.RB.sup.(0).

(28) At step S12 the transmitter sends to the terminal the allocation parameters, for example, indications allowing the terminal to deduce which type of subcarriers (subcarrier spacing configuration of the resource blocks) will be allocated to the terminal and therefore which set of formulae or lookup table will be necessary to decode the RIV value, if several sets are possible.

(29) At step S13 the transmitter defines the contiguous subcarriers it allocates to the terminal.

(30) At step S14 the transmitter sends the RIV value through a control channel. The RIV value is calculated with the RIV formula mentioned above based on the contiguous subcarriers the transmitter allocates to the terminal.

(31) Referring to FIG. 3B there is shown a flowchart representing the steps according to an aspect of the invention, to define by the terminal the subcarriers that are allocated to it.

(32) At step S21 the terminal receives from the transmitter the parameters concerning the cell settings including the carrier bandwidth BW and information on supported numerologies. More specifically the terminal receives from the transmitter information allowing the terminal to know directly or deduce at least the following parameters: f.sub.0, f.sub.2, N.sub.RB.sup.(0).

(33) At step S22 the terminal receives from the transmitter the allocation parameters, for example indications allowing the terminal to deduce which type of subcarriers (subcarrier spacing configuration of the resource blocks) will be allocated to it and therefore which set of formula or lookup table will be necessary to decode the RIV value, if several sets are possible.

(34) At step S23 the terminal receives from the transmitter through a control channel, the RIV value corresponding to the subcarriers allocated to the terminal.

(35) At step S24 based on: the knowledge of N.sub.RB.sup.(0) and q.sub.2=f.sub.2/f.sub.0=4, the terminal computes: r.sub.2 the remainder of the division of N.sub.RB.sup.(0) by 4; and

(36) p 2 = .Math. N RB ( 0 ) 4 .Math. ; and the reception of its RIV value the terminal computes:

(37) P = .Math. RIV p 2 .Math. ; and R=rem (RIV, p.sub.2); and

(38) NRB start ( 0 ) = { P if P + 4 ( R + 1 ) N RB ( 0 ) N RB ( 0 ) - 3 + r 2 - P otherwise L = { R + 1 if P + 4 .Math. ( R + 1 ) N RB ( 0 ) p 2 + R otherwise

(39) Based on the values NRB.sub.start.sup.(0) and L, decoded by the terminal, the terminal can determine a unique f.sub.start and a unique f.sub.last as shown above.

(40) Of course, the present invention is not limited to the examples of embodiments described in details above, but encompasses also further alternative embodiments.

(41) For example the present invention refers to carrier band of a specific bandwidth but the invention can also be implemented on a pre-defined portion of the entire carrier band, more specifically the pre-defined portion seen by a terminal as the maximum band where its own resource allocation and control signaling can occur.