A method for efficiently scheduling virtual resource blocks to physical resource blocks is disclosed. In a wireless mobile communication system that supports a resource block group (RBG) allocation scheme, for distributed mapping of consecutively allocated virtual resource blocks to physical resource blocks, there is proposed a mapping method capable of increasing the number of distributed virtual resource blocks to a maximum while satisfying gap limitations, when the length of the physical resource blocks is different from the length of the distributed virtual resource blocks. Also, the number of distributed virtual resource blocks and the structure of an interleaver are limited for efficient scheduling.
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1. A method for transmitting downlink data using resource blocks at a base station in a wireless mobile communication system, the method comprising:
transmitting downlink data mapped to physical resource blocks (PRBs) to a user equipment,
wherein:
indexes of virtual resource blocks (vrbs) are mapped to indexes of the PRBs for each of Ns slots of a subframe, Ns denoting a number of slots included in the subframe,
indexes of the PRBs for an odd-numbered slot are shifted with respect to indexes of the PRBs for an even-numbered slot based on a predetermined gap, and
an index of one of the PRBs on each of the Ns slots that are mapped to an index of one of the vrbs is determined by using Ngap and NDVRB
where Ngap is a value of the predetermined gap and NDVRB is a number of the vrbs.
11. A base station transmitting downlink data using resource blocks in a wireless mobile communication system, the base station comprising:
a processor configured to control an operation of the base station; and
a memory unit driven by the processor,
wherein:
the processor is configured to transmit downlink data mapped to physical resource blocks (PRBs) to a user equipment,
indexes of virtual resource blocks (vrbs) are mapped to indexes of the PRBs for Ns slots of a subframe, the Ns denoting a number of slots included in the subframe
indexes of the PRBs for an odd-numbered slot are shifted with respect to indexes of the PRBs for an even-numbered slot based on a predetermined gap,
an index of one of the PRBs on each of the Ns slots that is mapped to an index of one of the vrbs is determined by using Ngap and NDVRB where Ngap is a value of the predetermined gap and NDVRB is a number of the vrbs.
6. A method for receiving downlink data using resource blocks at a user equipment in a wireless mobile communication system, the method comprising:
receiving downlink control information including resource allocation information for the downlink data from a base station; and
receiving the downlink data mapped to physical resource blocks (PRBs) based on the downlink control information,
wherein:
the resource allocation information indicates virtual resource block (vrb) allocations for the user equipment,
indexes of the PRBs to which the downlink data are mapped are determined based on a mapping relationship between virtual resource blocks (vrbs) and the PRBs,
the mapping relationship is defined as indexes of the vrbs that are mapped to the indexes of the PRBs for Ns slots of a subframe, Ns denoting a number of slots included in the subframe,
indexes of the PRBs for an odd-numbered slot are shifted with respect to indexes of the PRBs for an even-numbered slot based on a predetermined gap, and
an index of one of the PRBs on each of the Ns slots that is mapped to an index of one of the vrbs is determined by using Ngap and NDVRB where Ngap is a value of the predetermined gap and NDVRB is a number of the vrbs.
12. A user equipment receiving downlink data using resource blocks in a wireless mobile communication system, the user equipment comprising:
a processor configured to control an operation of the user equipment; and
a memory unit driven by the processor,
wherein:
the processor is configured to:
receive downlink control information including resource allocation information for the downlink data from a base station; and
receive the downlink data mapped to physical resource blocks (PRBs) based on the downlink control information,
the resource allocation information indicates virtual resource block (vrb) allocations for the user equipment,
indexes of the PRBs to which the downlink data are mapped are determined based on a mapping relationship between virtual resource blocks (vrbs) and the PRBs,
the mapping relationship is defined as indexes of the vrbs that are mapped to the indexes of the PRBs for Ns slots of a subframe, Ns denoting a number of slots included in the subframe,
indexes of the PRBs for an odd-numbered slot are shifted with respect to indexes of the PRBs for an even-numbered slot based on a predetermined gap, and
an index of one of the PRBs on each of the Ns slots that is mapped to an index of one of the vrbs is determined by using Ngap and NDVRB where Ngap is a value of the predetermined gap and NDVRB is a number of the vrbs.
2. The method according to
the indexes of the vrbs are interleaved by a block interleaver,
an index o1,d of one of the PRBs on the odd-numbered slot of Ns slots that is mapped to a given index d of one of the vrbs is set to p1,d+Ngap−NDVRB/2 if a temporary index p1,d of one of the PRBs on the odd-numbered slot that is mapped to the index d by the block interleaver is greater than or equal to NDVRB/2,
an index o2,d of the one of the PRBs on the even-numbered slot of Ns slots that is mapped to the index d is set to p2,d+Ngap−NDVRB/2 if a temporary index p2,d of one of the PRBs on the even-numbered slot that is mapped to the index d by the block interleaver is greater than or equal to NDVRB/2, and
d has an integer value in a range from 0 to NDVRB−1, and p1,d, p2,d, o1,d, and o2,d have an integer value in a range from 0 to NPRB−1, NPRB being a number of the PRBs in the wireless mobile communication system.
3. The method according to
expression (1) is
expression (2) is
p2,d=mod(p1,d+NDVRB/2,NDVRB) where R is a number of rows of the block interleaver, C is a number of columns of the block interleaver, NDVRB is a number of resource blocks used for the vrbs, and ‘mod’ means a modulo operation.
4. The method according to
wherein:
a number of rows of the block interleaver (R) is given as expression (1) and a number of nulls (Nnull) filled in the block interleaver is given as expression (2), wherein
expression (1) is
R=Ninterleaver/C=┌NDVRB/(C·MRBG)┐·MRBG Ninterleaver=┌NDVRB/(C·MRBG)┐·C·MRBG, and expression (2) is
Nnull=Ninterleaver−NDVRB=┌NDVRB/(C·MRBG)┐·C·MRBG−NDVRB where C is a number of columns of the block interleaver and MRBG is a number of consecutive PRBs constituting one resource block group (RBG).
5. The method according to
7. The method according to
the indexes of the vrbs are interleaved by a block interleaver,
an index o1,d of one of the PRBs on the odd-numbered slot of Ns slots that is mapped to a given index d of one of the vrbs is set to p1,d+Ngap−NDVRB/2 if a temporary index p1,d of one of the PRBs on the odd-numbered slot that is mapped to the index d by the block interleaver is greater than or equal to NDVRB/2,
an index o2,d of the one of the PRBs on the even-numbered slot of Ns slots that is mapped to the index d is set to p2,d+Ngap−NDVRB/2 if a temporary index p2,d of one of the PRBs on the even-numbered slot that is mapped to the index d by the block interleaver is greater than or equal to NDVRB/2, and
d has an integer value in a range from 0 to NDVRB−1, and p1,d, p2,d, o1,d, and o2,d have an integer value in a range from 0 to NPRB−1, NPRB being a number of the PRBs in the wireless mobile communication system.
8. The method according to
expression (1) is
expression (2) is
p2,d=mod(p1,d+NDVRB/2,NDVRB) where R is a number of rows of the block interleaver, C is a number of columns of the block interleaver, NDVRB is a number of resource blocks used for the vrbs, and ‘mod’ means a modulo operation.
9. The method according to
expression (1) is
R=Ninterleaver/C=┌NDVRB/(C·MRBG)┐·MRBG Ninterleaver=┌NDVRB/(C·MRBG)┐·C·MRBG; and expression (2) is
Nnull=Ninterleaver−NDVRB=┌NDVRB/(C·MRBG)┐·C·MRBG−NDVRB where C is a number of columns of the block interleaver and MRBG is a number of consecutive PRBs constituting the RBG.
10. The method according to
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This application is a continuation of U.S. application Ser. No. 12/349,465, filed on Jan. 6, 2009, now U.S. Pat. No. 7,729,377, which claims the benefit of earlier filing date and right of priority to Korean Patent Application No. 10-2008-0131113, filed on Dec. 22, 2008, and also claims the benefit of U.S. Provisional Application Ser. Nos. 61/019,589, filed on Jan. 7, 2008, 61/028,186, filed on Feb. 12, 2008, 61/033,358, filed on Mar. 3, 2008, 61/037,302, filed on Mar. 17, 2008, 61/024,886, filed on Jan. 30, 2008, 61/038,778, filed on Mar. 24, 2008, 61/026,113, filed on Feb. 4, 2008, and 61/028,511, filed on Feb. 13, 2008, the contents of which are all hereby incorporated by reference herein in their entirety.
1. Field of the Invention
The present invention relates to a broadband wireless mobile communication system, and more particularly, to radio resource scheduling for uplink/downlink packet data transmission in a cellular OFDM wireless packet communication system.
2. Discussion of the Related Art
In a cellular orthogonal frequency division multiplex (OFDM) wireless packet communication system, uplink/downlink data packet transmission is made on a subframe basis and one subframe is defined by a certain time interval including a plurality of OFDM symbols.
The Third Generation Partnership Project (3GPP) supports a type 1 radio frame structure applicable to frequency division duplex (FDD), and a type 2 radio frame structure applicable to time division duplex (TDD). The structure of a type 1 radio frame is shown in
A signal transmitted in each slot can be described by a resource grid including NRBDL NSCRB subcarriers and NsymbDL OFDM symbols. Here, NRBDL represents the number of resource blocks (RBs) in a downlink, NSCRB represents the number of subcarriers constituting one RB, and NsynmbDL represents the number of OFDM symbols in one downlink slot. The structure of this resource grid is shown in
RBs are used to describe a mapping relationship between certain physical channels and resource elements. The RBs can be classified into physical resource blocks (PRBs) and virtual resource blocks (VRBs), which means that a RB may be either one of a PRB or a VRB. A mapping relationship between the VRBs and the PRBs can be described on a subframe basis. In more detail, it can be described in units of each of slots constituting one subframe. Also, the mapping relationship between the VRBs and the PRBs can be described using a mapping relationship between indexes of the VRBs and indexes of PRBs. A detailed description of this will be further given in embodiments of the present invention.
A PRB is defined by NsymbDL consecutive OFDM symbols in a time domain and NSCRB consecutive subcarriers in a frequency domain. One PRB is therefore composed of NDsymbDL NSCRB resource elements. The PRBs are assigned numbers from 0 to NRBDL−1 in the frequency domain.
A VRB can have the same size as that of the PRB. There are two types of VRBs defined, the first one being a localized type and the second one being a distributed type. For each VRB type, a pair of VRBs have a single VRB index in common (may hereinafter be referred to as a ‘VRB number’) and are allocated over two slots of one subframe. In other words, NRBDL VRBs belonging to a first one of two slots constituting one subframe are each assigned any one index of 0 to NRBDL−1, and NRDL VRBs belonging to a second one of the two slots are likewise each assigned any one index of 0 to NRBDL−1.
The index of a VRB corresponding to a specific virtual frequency band of the first slot has the same value as that of the index of a VRB corresponding to the specific virtual frequency band of the second slot. That is, assuming that a VRB corresponding to an ith virtual frequency band of the first slot is denoted by VRB1(i), a VRB corresponding to a jth virtual frequency band of the second slot is denoted by VRB2(j) and index numbers of the VRB1(i) and VRB2(j) are denoted by index(VRB1(i)) and index(VRB2(j)), respectively, a relationship of index(VRB1(k))=index(VRB2(k)) is established (see
Likewise, the index of a PRB corresponding to a specific frequency band of the first slot has the same value as that of the index of a PRB corresponding to the specific frequency band of the second slot. That is, assuming that a PRB corresponding to an ith frequency band of the first slot is denoted by PRB1(i), a PRB corresponding to a jth frequency band of the second slot is denoted by PRB2(j) and index numbers of the PRB1(i) and PRB2(j) are denoted by index(PRB1(i)) and index(PRB2(j)), respectively, a relationship of index(PRB1(k))=index(PRB2(k)) is established (see
Some of the plurality of aforementioned VRBs are allocated as the localized type and the others are allocated as the distributed type. Hereinafter, the VRBs allocated as the localized type will be referred to as ‘localized virtual resource blocks (LVRBs)’ and the VRBs allocated as the distributed type will be referred to as ‘distributed virtual resource blocks (DVRBs)’.
The localized VRBs (LVRBs) are directly mapped to PRBs and the indexes of the LVRBs correspond to the indexes of the PRBs. Also, LVRBs of index i correspond to PRBs of index i. That is, an LVRB1 having the index i corresponds to a PRB1 having the index i, and an LVRB2 having the index i corresponds to a PRB2 having the index i (see
The distributed VRBs (DVRBs) may not be directly mapped to PRBs. That is, the indexes of the DVRBs can be mapped to the PRBs after being subjected to a series of processes.
First, the order of a sequence of consecutive indexes of the DVRBs can be interleaved by a block interleaver. Here, the sequence of consecutive indexes means that the index number is sequentially incremented by one beginning with 0. A sequence of indexes outputted from the interleaver is sequentially mapped to a sequence of consecutive indexes of PRB1s (see
On the other hand, in the above processes, a sequence of consecutive indexes of the DVRBs may be sequentially mapped to the sequence of consecutive indexes of the PRB1s without passing through the interleaver. Also, the sequence of consecutive indexes of the DVRBs may be cyclically shifted by the predetermined number without passing through the interleaver and the cyclically shifted index sequence may be sequentially mapped to the sequence of consecutive indexes of the PRB2s.
According to the above-mentioned processes of mapping DVRBs to PRBs, a PRB1(i) and a PRB2(i) having the same index i can be mapped to a DVRB1(m) and a DVRB2(n) having different indexes m and n. For example, referring to
In the case where VRB(1)s, among the VRBs, are allocated as DVRBs as in
In a broadband wireless mobile communication system using a multi-carrier, radio resources can be allocated to each terminal with a LVRB and/or DVRB scheme. The information indicating which scheme is used can be transmitted with a bitmap format. At this time, the allocation of radio resources to each terminal can be carried out in units of one RB. In this case, resources can be allocated with a granularity of ‘1’ RB, but a large amount of bit overhead is required to transmit the allocation information with the bitmap format. Alternatively, an RB group (RBG) consisting of PRBs of k consecutive indexes (e.g., k=3) may be defined and resources may be allocated with a granularity of ‘1’ RBG. In this case, the RB allocation is not sophisticatedly performed, but there is an advantage that bit overhead is reduced.
In this case, LVRBs can be mapped to PRBs on an RBG basis. For example, PRBs having three consecutive indexes, a PRB1(i), PRB1(i+1), PRB1(i+2), PRB2(i), PRB2(i+1) and PRB2(i+2), may constitute one RBG, and LVRBs may be mapped to this RBG in units of an RBG. However, in the case where one or more of the PRB1(i), PRB1(i+1), PRB1(i+2), PRB2(i), PRB2(i+1) and PRB2(i+2) were previously mapped by DVRBs, this RBG cannot be mapped by LVRBs on an RBG basis. That is, the DVRB mapping rules may restrict the RBG-unit LVRB mapping.
As mentioned above, because the DVRB mapping rules may affect the LVRB mapping, there is a need to determine the DVRB mapping rules in consideration of the LVRB mapping.
An object of the present invention devised to solve the problem lies on a resource scheduling method for efficiently combining scheduling of an FSS scheme and scheduling of an FDS scheme.
The object of the present invention can be achieved by providing, in a wireless mobile communication system that supports a resource allocation scheme in which one resource block group (RBG) including consecutive physical resource blocks is indicated by one bit, a resource block mapping method for distributively mapping consecutively allocated virtual resource blocks to the physical resource blocks, the method including: interleaving, using a block interleaver, indexes of the virtual resource blocks determined from a resource indication value (RIV) indicating a start index number of the virtual resource blocks and a length of the virtual resource blocks; and sequentially mapping the interleaved indexes to indexes of the physical resource blocks on a first slot of one subframe, the subframe including the first slot and a second slot, and sequentially mapping indexes obtained by cyclically shifting the interleaved indexes by a gap for the distribution to the indexes of the physical resource blocks on the second slot, wherein the gap is a multiple of a square of the number (MRBG) of the consecutive physical resource blocks constituting the RBG.
When a degree of the block interleaver is defined as the number (C=4) of columns of the block interleaver, the number (R) of rows of the block interleaver may be given as in expression (1) and the number (Nnull) of nulls filled in the block interleaver may be given as in expression (2).
R=Ninterleaver/C=┌NDPRB/(C·MRBG)┐·MRBG
Ninterleaver=┌NDVRB/(C·MRBG)┐·C·MRBG [Expression (1)].
where MRBG is the number of the consecutive physical resource blocks constituting the RBG, and NDVRB is the number of the distributively allocated virtual resource blocks.
Nnull=Ninterleaver−NDVRB=┌NDVRB/(C·MRBG)┐·C·MRBG−NDVRB
Ninterleaver=┌NDVRB/(C·M·RBG)┐·C·MRBG [Expression (2)]
where MRBG is the number of the consecutive physical resource blocks constituting the RBG, and NDVRB is the number of the distributively allocated virtual resource blocks.
A degree of the block interleaver may be equal to a diversity order (NDivOrder) determined by the distribution.
When an index d of one of the distributively allocated virtual resource, blocks is given, an index P1,d of corresponding one of the physical resource blocks on the first slot mapped to the index d may be given as in expression (3) and an index P2,d of corresponding one of the physical resource blocks on the second slot mapped to the index d may be given as in expression (4). Here, R is the number of rows of the block interleaver, C is the number of columns of the block interleaver, NDVRB is the number of resource blocks used for the distributively allocated virtual resource blocks, Nnull is the number of nulls filled in the block interleaver, and mod means a modulo operation.
Here, C may be equal to the degree of the block interleaver.
The index P1,d may be p1,d+NPRB−NDVRB when it is larger than NDVRB/2, and the index P2,d may be p2,d+NPRB−NDVRB when it is larger than NDVRB/2. Here, NPRB is the number of physical resource blocks in the system.
When the number (NDVRB) of the virtual resource blocks is not a multiple of the degree of the block interleaver, the step of interleaving may include dividing the interleaver into groups of the number (ND) of physical resource blocks to which one virtual resource block is mapped and uniformly distributing nulls to the divided groups.
The groups may correspond to rows of the block interleaver, respectively, when a degree of the block interleaver is the number of the rows of the block interleaver, and to columns of the block interleaver, respectively, when the degree of the block interleaver is the number of the columns of the block interleaver.
In another aspect of the present invention, provided herein is, in a wireless mobile communication system that supports a resource allocation scheme in which one resource block group (RBG) including consecutive physical resource blocks is indicated by one bit, a resource block mapping method for distributively mapping consecutively allocated virtual resource blocks to the physical resource blocks, the method including: interleaving, using a block interleaver, indexes of the virtual resource blocks determined from a resource indication value (RIV) indicating a start index number of the virtual resource blocks and a length of the virtual resource blocks; and sequentially mapping the interleaved indexes to indexes of the physical resource blocks on a first slot of one subframe, the subframe including the first slot and a second slot, and sequentially mapping indexes obtained by cyclically shifting the interleaved indexes by a gap for the distribution to the indexes of the physical resource blocks on the second slot, wherein the gap (Ngap) for the distribution is given as in expression (5).
Ngap=round(NPRB/(2·MRBG2))·MRBG2 [Expression (5)]
where MRBG 1 is the number of the consecutive physical resource blocks constituting the RBG, and NPRB is the number of physical resource blocks in the system.
When nulls are allowed to be inputted to the block interleaver, the number (NDVRB) of the distributively allocated virtual resource blocks may be given as in expression (6).
NDVRB=min(NPRB−Ngap, Ngap)·2 [Expression (6)]
When an index d of one of the distributively allocated virtual resource blocks is given, an index P1,d of corresponding one of the physical resource blocks on the first slot mapped to the index d may be p1,d+NPRB−NDVRB when it is larger than NDVRB/2, and an index P2,d of corresponding one of the physical resource blocks on the second slot mapped to the index d may be p2,d+NPRB−NDVRB when it is larger than NDVRB/2, wherein NDVRB is the number of resource blocks used for the distributively allocated virtual resource blocks.
In another aspect of the present invention, provided herein is, in a wireless mobile communication system that supports a resource allocation scheme in which one resource block group (RBG) including consecutive physical resource blocks is indicated by one bit, a resource block mapping method for distributively mapping consecutively allocated virtual resource blocks to the physical resource blocks, the method including: detecting a resource indication value (RIV) indicating a start index number of the virtual resource blocks and a length of the virtual resource blocks and determining indexes of the virtual resource blocks from the detected resource indication value; and interleaving the determined indexes of the virtual resource blocks using a block interleaver and distributively mapping the virtual resource blocks to the physical resource blocks, wherein a degree of the block interleaver is equal to a diversity order (NDivOrder) determined by the distribution.
In another aspect of the present invention, provided herein is, in a wireless mobile communication system that supports a resource allocation scheme in which one resource block group (RBG) including consecutive physical resource blocks is indicated by one bit, a resource block mapping method for distributively mapping consecutively allocated virtual resource blocks to the physical resource blocks, the method including: determining indexes of the virtual resource blocks from a resource indication value (RIV) indicating a start index number of the virtual resource blocks and a length of the virtual resource blocks; and interleaving the determined indexes of the virtual resource blocks using a block interleaver and distributively mapping the virtual resource blocks to the physical resource blocks, wherein, when the number (NDVRB) of the virtual resource blocks is not a multiple of a degree of the block interleaver, the step of mapping includes dividing the interleaver into groups of the number (ND) of physical resource blocks to which one virtual resource block is mapped and uniformly distributing nulls to the divided groups.
The groups may correspond to rows of the block interleaver, respectively, when a degree of the block interleaver is the number of the rows of the block interleaver, and to columns of the block interleaver, respectively, when the degree of the block interleaver is the number of the columns of the block interleaver.
The control information may be a DCI transmitted over a PDCCH.
The gap may be a function of a system bandwidth.
When an index p of one of the physical resource blocks is given, an interleaved index dp1 mapped to the index p may be given as in expression (7) or expression (8), and a cyclically shifted index dp2 mapped to the index p may be given as in expression (9) or expression (10). Here, R is the number of rows of the block interleaver, C is the number of columns of the block interleaver, NDVRB is the number of resource blocks used for the distributively allocated virtual resource blocks, and mod means a modulo operation.
The diversity order NDivOrder) may be a multiple of the number (ND) of physical resource blocks to which one virtual resource block is mapped.
The gap may be 0 when the number of the virtual resource blocks is larger than or equal to a predetermined threshold value (Mth).
The resource block mapping method may further include receiving information about the gap, the gap being determined by the received gap information.
in another aspect of the present invention, provided herein is, in a wireless mobile communication system that supports an RBG resource allocation scheme and a subset resource allocation scheme, a resource block mapping method for distributively mapping consecutively allocated virtual resource blocks to physical resource blocks, the method including: receiving control information including resource block allocation information indicating distributed allocation of the virtual resource blocks, and indexes of the virtual resource blocks; and interleaving the indexes of the virtual resource blocks using a block interleaver, wherein the step of interleaving includes, until the indexes of the virtual resource blocks are mapped to all indexes of physical resource blocks belonging to any one of a plurality of RBG subsets, preventing the indexes of the virtual resource blocks from being mapped to indexes of physical resource blocks belonging to a different one of the RBG subsets.
The resource block mapping method may further include sequentially mapping the interleaved indexes to indexes of the physical resource blocks on a first slot of one subframe, the subframe including the first slot and a second slot, and sequentially mapping indexes obtained by cyclically shifting the interleaved indexes by a gap for the distribution to the indexes of the physical resource blocks on the second slot, wherein the gap for the distribution is determined such that the virtual resource blocks mapped on the first slot and the virtual resource blocks mapped on the second slot are included in the same subset.
The number (NDVRB) of the virtual resource blocks may be a multiple of a diversity order (NDivOrder) determined by the distribution.
The number (NDVRB) of the virtual resource blocks may be a multiple of the number MRBG of the consecutive physical resource blocks constituting the RBG.
The number (NDVRB) of the virtual resource blocks may be a multiple of a value obtained by multiplying, the number MRBG, of the consecutive physical resource blocks constituting the RBG by the number (ND) of physical resource blocks to which one virtual resource block is mapped.
The number (NDVRB) of the virtual resource blocks may be a multiple of a value obtained by multiplying the square (MRBG2) of the number of the consecutive physical resource blocks constituting the RBG by the number (ND) of physical resource blocks to which one virtual resource block is mapped.
The number NDVRB of the virtual resource blocks may be a common multiple of a value obtained by multiplying the number (MRBG) of the consecutive physical resource blocks constituting the RBG by the number (ND) of physical resource blocks to which one virtual resource block is mapped and a degree (D) of the block interleaver.
The degree (D) of the block interleaver may be a multiple of the number (ND) of physical resource blocks to which one virtual resource block is mapped.
The number NDVRB of the virtual resource blocks may be a common multiple of a value obtained by multiplying a square (MRBG2) of the number of the consecutive physical resource blocks constituting the RBG by the number (ND) of physical resource blocks to which one virtual resource block is mapped and a degree (D) of the block interleaver.
The degree (D) of the block interleaver may be a multiple of the number (ND) of physical resource blocks to which one virtual resource block is mapped.
The number NDVRB of the virtual resource blocks may be a common multiple of a value obtained by multiplying a degree (D) of the block interleaver by a square (MRBG2) of the number of the consecutive physical resource blocks constituting the RBG and a value obtained by multiplying the number (ND)) of physical resource blocks to which one virtual resource block is mapped by the square (MRBG2) of the number of the consecutive physical resource blocks constituting the RBG.
The degree (D) of the block interleaver may be a multiple of the number (ND) of physical resource blocks to which one virtual resource block is mapped.
The aforementioned various aspects of the present invention are all applicable to a base station and/or mobile station. In the case where the aforementioned aspects of the present invention are applied to the mobile station, the resource block mapping method may further include receiving the resource indication value (RIV) from the mobile station of the wireless mobile communication system, prior to the step of interleaving or the step of determining the indexes of the virtual resource blocks.
According to the present invention, it is possible to efficiently combine scheduling of an FSS scheme and scheduling of an FDS scheme and simply implement a scheduling information transfer method.
The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention.
In the drawings:
Reference will now be made in detail to the preferred embodiments of the present invention with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention, rather than to show the only embodiments that can be implemented according to the invention. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without such specific details. For example, the following description will be given centering around specific terms, but the present invention is not limited thereto and any other terms may be used to represent the same meanings. Also, wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
In the case where a subframe consists of a first slot and a second slot, index(PRB1(i)) represents an index of a PRB of an ith frequency band of the first slot, index(PRB2(j)) represents an index of a PRB of a jth frequency band of the second slot, and a relationship of index(PRB1(k))=index(PRB2(k)) is established, as stated previously. Also, index(VRB1(i)) represents an index of a VRB of an ith virtual frequency band of the first slot, index(VRB2(j)) represents an index of a VRB of a jth virtual frequency band of the second slot, and a relationship of index(VRB1(k))=index(VRB2(k)) is established. At this time, VRB1s are mapped to PRB1s, and VRB2s are mapped to PRB2s. Also, VRBs are classified into DVRBs and LVRBs.
The rules for mapping LVRB1s to PRB1s and the rules for mapping LVRB2s to PRB2s are the same. However, the rules for mapping DVRB1s to PRB1s and the rules for mapping DVRB2s to PRB2s are different. That is, DVRBs are ‘divided’ and mapped to PRBs.
In the 3GPP, one RB is defined in units of one slot. However, in the detailed description of the invention, one RB is defined in units of one subframe, and this RB is divided into ND sub-RBs on a time axis, so that the DVRB mapping rules are generalized and described. For example, in the case where ND=2, a PRB defined in units of one subframe is divided into a first sub-PRB and a second sub-PRB, and a VRB defined in units of one subframe is divided into a first sub-VRB and a second sub-VRB.
In this case, the first sub-PRB corresponds to the aforementioned PRB1, and the second sub-PRB corresponds to the aforementioned PRB2. Also, the first sub-VRB corresponds to the aforementioned VRB1, and the second sub-VRB corresponds. to the aforementioned VRB2. Also, in both the detailed description of the invention and the 3GPP, the DVRB mapping rules for obtaining a frequency effect is described on the basis of one subframe. Therefore, it will be understood that all embodiments of the detailed description of the invention are concepts including an RB mapping method in the 3GPP.
Hereinafter, terms used in the detailed description of this application are defined as follows.
A ‘resource element (RE)’ represents a smallest frequency-time unit in which data or a modulated symbol of a control channel is mapped. Provided that a signal is transmitted in one OFDM symbol over M subcarriers and N OFDM symbols are transmitted in one subframe, M×N REs are present in one subframe.
A ‘physical resource block (PRB)’ represents a unit frequency-time resource for data transmission. In general, one PRB consists of a plurality of consecutive REs in a frequency-time domain and a plurality of PRBs are defined in one subframe.
A ‘virtual resource block (VRB)’ represents a virtual unit resource for data transmission. In general, the number of REs included in one VRB is equal to that of REs included in one PRB, and, when data is transmitted, one VRB can be mapped to one PRB or some areas of a plurality of PRBs.
A ‘localized virtual resource block (LVRB)’ is one type of the VRB. One LVRB is mapped to one PRB. A PRB mapped to one LVRB is different from a PRB mapped to another LVRB.
A ‘distributed virtual resource block (DVRB)’ is another type of the VRB. One DVRB is mapped to a plurality of PRBs in a distributed manner.
‘ND’=‘Nd’ represents the number of PRBs to which one DVRB is mapped.
‘NPRB’ represents the number of PRBs in a system. In the case where the band of the system is divided, NPRB may be the number of PRBs in the divided part.
‘NLVRB’ represents the number of LVRBs available in the system.
‘NDVRB’ represents the number of DVRBs available in the system.
‘NLVRB
‘NDVRB
‘Nsubset’ represents the number of subsets.
‘NDivOrder’ represents a diversity order required in the system. Here, the diversity order is defined by the number of RBs which are not adjacent to each other.
Here, the “number of RBs” means the number of RBs divided on a frequency axis. That is, even in the case where RBs can be divided by time slots constituting a subframe, the “number of RBs” means the number of RBs divided on the frequency axis of the same slot.
As can be seen from
Downlink data transmission from a base station to a specific terminal or uplink data transmission from the specific terminal to the base station is made through one or more VRBs in one subframe. When the base station transmits data to the specific terminal, it has to notify the terminal of which one of the VRBs is used for data transmission. Also, in order to enable the specific terminal to transmit data, the base station has to notify the terminal of which one of the VRBs is allowed to use for data transmission.
Data transmission schemes can be broadly classified into a frequency diversity scheduling (FDS) scheme and a frequency selective scheduling (FSS) scheme. The FDS scheme is a scheme that obtains a reception performance gain through frequency diversity, and the FSS scheme is a scheme that obtains a reception performance gain through frequency selective scheduling.
In the FDS scheme, a transmission stage transmits one data packet over subcarriers widely distributed in a system frequency domain so that symbols in the data packet can experience various radio channel fadings. Therefore, an improvement in reception performance is obtained by preventing the entire data packet from being subject to unfavorable fading. In contrast, in the FSS scheme, an improvement in reception performance is obtained by transmitting the data packet over one or more consecutive frequency areas in the system frequency domain which are in a favorable fading state. In a cellular OFDM wireless packet communication system, a plurality of terminals are present in one cell. At this time, because the radio channel conditions of the respective terminals have different characteristics, it is necessary to perform data transmission of the FDS scheme with respect to a certain terminal and data transmission of the FSS scheme with respect to a different terminal even within one subframe. As a result, a detailed FDS transmission scheme and a detailed FSS transmission scheme must be designed such that the two schemes can be efficiently multiplexed within one subframe. On the other hand, in the FSS scheme, a gain can be obtained by selectively using a band favorable to a UE among all available bands. In contrast, in the FDS scheme, an evaluation is not made as to whether a specific band is good or bad, and, as long as a frequency separation capable of adequately obtaining a diversity is maintained, there is no need to select and transmit a specific frequency band. Accordingly, it is advantageous to an improvement in entire system performance to perform the frequency selective scheduling of the FSS scheme preferentially when scheduling.
In the FSS scheme, because data is transmitted using subcarriers consecutively contiguous in the frequency domain, it is preferable that the data is transmitted using LVRBs. At this time, provided that NPRB PRBs are present in one subframe and a maximum of NLVRB LVRBs are available within the system, the base station can transmit bitmap information of NLVRB bits to each terminal to notify the terminal of which one of the LVRBs through which downlink data will be transmitted or which one of the LVRBs through which uplink data can be transmitted. That is, each bit of the NLVRB-bit bitmap information, which is transmitted to each terminal as scheduling information, indicates whether data will or can be transmitted through an LVRB corresponding to this bit, among the NLVRB LVRBs. This scheme is disadvantageous in that, when the number NLVRB becomes larger, the number of bits to be transmitted to each terminal becomes larger in proportion thereto.
On the other hand, provided that a terminal can be allocated only one set of contiguous RBs, information of the allocated RBs can be expressed by a start point of the RBs and the number thereof. This scheme is referred to as a ‘compact scheme’ in this document.
In this case, as shown in
On the other hand, for a method for notifying a user equipment (UE) of DVRB allocation, it is necessary to previously promise the positions of respective divided parts of DVRBs distributively transmitted for a diversity gain. Alternatively, additional information may be required to directly notify the positions. Preferably, provided that the number of bits for signaling for the DVRBs is set to be equal to the number of bits in LVRB transmission of the above-stated compact scheme, it is possible to simplify a signaling bit format in a downlink. As a result, there are advantages that the same channel coding can be used, etc.
Here, in the case where one UE is allocated a plurality of DVRBs, this UE is notified of a DVRB index of a start point of the DVRBs, a length (=the number of the allocated DVRBs), and a relative position difference between divided parts of each DVRB (e.g., a gap between the divided parts).
As shown in
In the method of
At this time, the value of the gap indicative of the relative position difference between the divided parts can be expressed in two ways. Firstly, the gap value can be expressed by a difference between DVRB indexes. Secondly, the gap value can be expressed by a difference between indexes of PRBs to which a DVRB is mapped. In the case of
As can be seen from
As a result, there is a need for a method to limit the diversity order to a proper level to carry out the distributed allocation.
A first embodiment and second embodiment of the present invention are directed to methods for setting a relative distance between divided parts of a DVRB mapped to PRBs to 0. In these embodiments, in a scheme for mapping consecutive DVRB indexes to spaced PRBs, when a plurality of DVRBs are allocated to one UE, respective divided parts of each of the DVRBs can be distributively allocated to different PRBs, thereby raising the diversity order. Alternatively, under the same conditions, the respective divided parts of each DVRB may be allocated to the same PRB, not distributively allocated to different PRBs. In this case, it is possible to reduce the number of PRBs to which DVRBs are distributively allocated, thus limiting the diversity order.
This embodiment is directed to a method for switching divided parts to a distributed/non-distributed mode by setting a reference value for the number of DVRBs allocated to one UE. Here, the ‘distributed mode’ refers to a mode where the gap between divided DVRB parts is not 0, and the ‘non-distributed mode’ refers to a mode where the gap between divided DVRB parts is 0.
Assume that the number of DVRBs allocated to one UE is M. When M is smaller than a specific reference value (=Mth), divided parts of each DVRB are distributively allocated, thereby raising the diversity order.
Conversely, when M is larger than or equal to the reference value (=Mth), the divided parts are allocated to the same PRB, not distributively allocated. This allocation of the divided parts to the same PRB can reduce the number of PRBs to which DVRBs are distributively mapped, thus limiting the diversity order.
That is, in the case where M is larger than or equal to the reference value Mth, a gap, which is a relative distance between divided parts of each DVRB mapped to PRBs, is set to 0.
For example, if the number of DVRBs is 2 under the condition that Mth=3, divided parts of each DVRB can be distributively mapped as shown in
This embodiment is directed to a method for switching divided parts to a distributed/non-distributed mode using a control signal. Here, the ‘distributed mode’ refers to a mode where the gap between divided DVRB parts is not 0, and the ‘non-distributed mode’ refers to a mode where the gap between divided DVRB parts is 0.
The embodiment 2 is a modified version of the embodiment 1. In the embodiment 2, Mth is not set, and, as needed, a control signal is transmitted and received to switch divided parts to the distributed/non-distributed mode. In response to the transmitted and received control signal, divided DVRB parts can be distributed to raise the diversity order or be mapped to the same PRB to lower the diversity order.
For example, the control signal may be defined to indicate the value of a gap, which is a relative distance between divided parts of each DVRB mapped to PRBs. That is, the control signal may be defined to indicate the gap value itself.
For example, in the case where the control signal indicates that Gap=3, divided DVRB parts are distributively mapped as shown in
As stated previously, in order to freely schedule the number NPRB of PRBs in the system on a PRB basis, it is necessary to transmit an NPRB-bit bitmap to each UE to be scheduled. When the number NPRB of PRBs in the system is large, overhead of control information is increased for transmission of the NPRB-bit bitmap. Therefore, consideration can be given to a method for scaling down a scheduling unit or dividing the entire band and then performing transmission in different scheduling units in only some bands.
In the 3GPP LTE, a bitmap configuration scheme has been proposed in consideration of overhead when the bitmap is transmitted as stated above.
A signal for resource allocation consists of a header 1501 and a bitmap 1502. The header 1501 indicates the structure of the bitmap 1502 being transmitted, namely, a bitmap scheme, by indicating a signaling scheme.
The bitmap scheme is classified into two types, an RBG scheme and a subset scheme.
In the RBG scheme, RBs are grouped into a plurality of groups. RBs are mapped in units of one group. That is, a plurality of RBs constituting one group have association of mapping. When the group size is larger, it is difficult to minutely perform resource allocation, but it is possible to reduce the number of bits of a bitmap. Referring to
In order to make up for it, the subset scheme is used. In this scheme, a plurality of RBGs are set as one subset, and resources are allocated on an RB basis within each subset. In order to use the 11-bit bitmap in the above-stated RBG scheme of
Provided that the header information 1501 just indicates which one of the RBG scheme and subset scheme is used and some bits of the bitmap used for the RBGs are used to indicate the subset type, all the RBs in all the subsets may not be utilized. For example, referring to
Although the subset indicator 1503 has been described in the above example to indicate the subset 1 1504 or 1505, it may indicate the subset 2 or subset 3. Accordingly, it can be seen that eight RBs can be mapped in units of one RB with respect to each combination of the subset indicator 1503 and shift indicator 1506. Also, referring to
Consideration can be given to use of a combination of the bitmap scheme using the RBG scheme and subset scheme and the compact scheme.
In the case where DVRBs are mapped and transmitted as shown in
Therefore, there is a need for a DVRB arrangement method capable of reducing the restriction in the LVRB scheduling.
Third to fifth embodiments of the present invention are directed to methods for setting a relative distance between divided parts of a DVRB mapped to PRBs to reduce an effect on LVRBs.
The embodiment 3 is directed to a method for, when mapping divided parts of DVRBs, mapping the divided parts to RBs belonging to one specific subset and then mapping the divided parts to RBs belonging to other subsets after mapping the divided parts to all the RBs of the specific subset.
According to this embodiment, when consecutive DVRB indexes are mapped to distributed PRBs, they can be distributively mapped within one subset and then mapped to other subsets when they cannot be mapped within the one subset any longer. Also, interleaving of consecutive DVRBs is performed within a subset.
DVRB0 to DVRB11 are distributively mapped within a subset 1 (1703), DVRB12 to DVRB22 are then distributively mapped within a subset 2 (1704), and DVRB23 to DVRB31 are then distributively mapped within a subset 3 (1705). This mapping can be carried Out by a method of using a block interleaver for each subset or any other method.
This arrangement can be achieved by controlling a block interleaver operation scheme.
The embodiment 4 is directed to a method for limiting mapping of divided DVRB parts to PR included in the same subset.
In the embodiment 4, gap information can be used to map divided parts of the same DVRB within the same subset. At this time, a parameter for all PRBs, such as the aforementioned ‘Gap’, may be used. Alternatively, another parameter for one subset, ‘Gapsubset’ may be used. This will hereinafter be described in detail.
It is possible to together use a method for distributively filling consecutive DVRBs within one subset and a method for mapping divided parts of each DVRB within the same subset. In this case, preferably, Gapsubset, which means a difference between PRB numbers within the same subset, can be used as information indicative of a relative position difference between divided DVRB parts. The meaning of Gapsubset can be understood from
The embodiment 5 is directed to a method for setting a relative distance between divided DVRB parts to a multiple of the square of the size of an RBG.
The limited setting of Gap to a multiple of the size of an RBG as in the present embodiment provides characteristics as follows. That is, when the relative distance between the divided DVRB parts is indicated as a relative position difference within one subset, it is set to a multiple of the size (P) of an RBG. Alternatively, when the relative distance between the divided DVRB parts is indicated as a position difference with respect to all PRBs, it is limited to a multiple of the square (P2) of the RBG size.
For example, referring to
In the case where a scheme based on this embodiment is used, because the probability that RBGs only some resource elements of each of which are used will belong to the same subset is high, it is expected that resource elements or RBs left not used are present in the same subset. Therefore, it is possible to efficiently use allocation of the subset scheme.
Referring to
In this case, DVRB indexes can be sequentially mapped to one subset (for example, subset 1) used for DVRBs, among the subsets, as shown in
On the other hand, it can be seen that DVRB indexes are consecutively arranged in
Hereinafter, a description will be given of a method for configuring an interleaver having a desired degree equal to a diversity order, according to one embodiment of the present invention.
In detail, in a method for mapping consecutive DVRB indexes to non-contiguous, distributed PRBs, a method is proposed which uses a block interleaver and configures the interleaver such that it has a degree equal to a target diversity order NDivOrder. The degree of the interleaver can be defined as follows.
That is, in a block interleaver having m rows and n columns, when data is written, the data is written while the index thereof is sequentially incremented. At this time, the writing is performed in such a manner that, after one column is completely filled, a column index is incremented by one and a next column is filled. In each column, the writing is performed while a row index is incremented. For reading from the interleaver, the reading is performed in such a manner that, after one row is completely read, a row index is incremented by one and a next row is read. In this case, the interleaver can be referred to as an m-degree interleaver.
Conversely, in a block interleaver having m rows and n columns, data writing may be performed in such a manner that, after one row is filled, the process proceeds to a next row, and data reading may be performed in such a manner that, after one column is read, the process proceeds to a next column. In this case, the interleaver can be referred to as an n-degree interleaver.
In detail, NDivOrder is limited to a multiple of ND. That is, NDivOrder=K·ND. Here, K is a positive integer. Also, a block interleaver of a degree NDivOrder is used.
Referring to
In the case where the interleaver is configured in this manner, a DVRB index order of a data sequence outputted from the interleaver can be used as an index order of first divided parts of DVRBs, and a DVRB index order of a data sequence obtained by cyclically shifting the outputted data sequence by NDVRB/ND can be used as an index order of the remaining divided parts. As a result, ND divided parts generated from DVRBs are mapped to only ND PRBs in pairs, and the difference between paired DVRB indexes is K.
For example, in
According to this embodiment, it is possible to effectively manage the relationship between DVRBs and PRBs to which the DVRBs are mapped.
Hereinafter, a method for filling nulls in a rectangular interleaver in accordance with one embodiment of the present invention will be described.
In the following description, the number of nulls filled in the interleaver may be represented by “Nnull”.
In accordance with the embodiment 6, it is possible to completely fill data in the interleaver because NDVRB is a multiple of NDivOrder. However, when NDVRB is not a multiple of NDivOrder, it is necessary to take a null filling method into consideration because it is impossible to completely fill data in the interleaver.
For a cyclic shift by NDVRB/ND, NDVRB should be a multiple of ND. In order to completely fill data in a rectangular interleaver, NDVRB should be a multiple of NDivOrder. However, when K>1, NDVRB may not be a multiple of NDivOrder, even though it is a multiple of ND. In this case, generally, data is sequentially filled in the block interleaver, and nulls are then filled in remaining spaces of the block interleaver. Thereafter, reading is performed. If the data is filled column by column, then the data is read row by row, or if the data is filled row by row, then the data is read column by column. In this case, no reading is performed for nulls.
Referring to
Meanwhile, when it is assumed that NRemain represents a remainder when NDVRB is divided by NDivOrder, nulls are filled in elements of a last column, except for elements corresponding to NRemain values, as shown in
In this embodiment, when nulls are to be filled in a rectangular block interleaver, NDivOrder corresponding to the degree of the interleaver is divided into ND groups each having a size of K, and nulls are uniformly distributed in all the groups. For example, as shown in
For example, where writing is performed in such a manner that values are sequentially filled, NRemain, values remain finally. When indexes corresponding to the remaining values are arranged in ND groups such that they are uniformly distributed, it is possible to uniformly arrange nulls. For example, in the case of
As a result, the difference between paired DVRB indexes can be maintained to be K or less (for example, K=3). Accordingly, there is an advantage in that a more efficient DVRB allocation can be achieved.
Hereinafter, a method for setting a relative distance between divided parts of each DVRB mapped to PRBs to 0 in accordance with one embodiment of the present invention will be described.
Meanwhile, where M DVRBs are allocated to one UE in a scheme for mapping consecutive DVRB indexes to non-contiguous, distributed PRBs, a reference value Mth for M may be set. Based on the reference value Mth, the divided parts of each DVRB may be distributively assigned to different PRBs, respectively, to raise the diversity order. Alternatively, the divided parts of each DVRB may be assigned to the same PRB without being distributed to different PRBs. In this case, it is possible to reduce the number of PRBs, to which DVRBs are distributively mapped, and thus to limit the diversity order.
That is, this method is a scheme in which the divided parts of each DVRB are distributed to raise the diversity order, when M is less than a specific reference value (=Mth), whereas, when M is not less than the specific reference value (=Mth), the divided parts of each DVRB are assigned to the same PRB without being distributed, to reduce the number of PRBs, to which DVRBs are distributively mapped, and thus to limit the diversity order.
That is, in this scheme, DVRB indexes of a data sequence outputted from the interleaver are applied, in common, to all divided parts of each DVRB such that they are mapped to PRBs, as shown in
Hereinafter, a method, in which both the above-described embodiments 6 and 8 are used, will be described in accordance with one embodiment of the present invention.
For example, referring to
Where the divided parts of each DVRB are mapped to distributed PRBs, respectively, the difference between the paired DVRB indexes is limited to a value of K or less. Accordingly, this scheme has no influence on DVRBs spaced apart from each other by a gap of more than K. Accordingly, it is possible to easily distinguish indexes usable in the “case in which the divided parts of each DVRB are mapped to the same PRB” from unusable indexes.
Hereinafter, a method for limiting an NDVRB, to prevent generation of a null, will be described in accordance with one embodiment of the present invention.
Again referring to
When the method of
In the illustrated interleaver, the number of RBs used for DVRBs, namely, NDVRB, is limited to a multiple of the diversity order, namely, NDivOrder, so that no null is filled in a rectangular matrix of the interleaver.
In a block interleaver of degree D, no null is filled in the rectangular matrix of the interleaver when the number of RBs used for DVRBs, namely, NDVRB, is limited to a multiple of D.
Hereinafter, several embodiments using the interleaver according to the present invention when K=2, and ND=2 will be described. The relation between DVRB and PRB indexes may be expressed by a mathematic expression.
Referring to the following description and
p: PRB index (0≦p≦NDVRB−1)
d: DVRB index (0≦d≦NDVRB−1)
p1,d: Index of a first slot of a PRB to which a given DVRB index d is mapped
p2,d: Index of a second slot of a PRB to which a given DVRB index d is mapped
dp1: DVRB index included in a first slot of a given PRB index p
dp2: DVRB index included in a second slot of a given PRB index p
Constants used in Expressions 1 to 11 expressing the relation between DVRB and PRB indexes are defined as follows.
C: Number of columns of the block interleaver
R: Number of rows of the block interleaver
NDVRB: Number of RBs used for DVRBs
R=┌NDVRB/C┐
NPRB: Number of PRBs in the system bandwidth.
When K=2, ND=2, and NDVRB is a multiple of C, the relation between PRB and DVRB indexes may be derived using Expressions 1 to 3. First, if a PRB index p is given, a DVRB index can be derived using Expression 1 or 2. In the following description, “mod(x,y)” means “x mod y”, and “mod” means a modulo operation. Also, “└·┘” means a descending operation, and represents a largest one of integers equal to or smaller than a numeral indicated in “└ ┘”. On the other hand, “┌·┐” means an ascending operation, and represents a smallest one of integers equal to or larger than a numeral indicated in “┌ ┐”. Also, “round(•)” represents an integer nearest to a numeral indicated in “( )”. “min(x,y)” represents the value which is not larger among x and y, whereas “max(x,y)” represents the value which is not smaller among x and y.
On the other hand, when NDVRB is a multiple of C, and a DVRB index d is given, a PRB index can be derived using Expression 3.
p1,d=mod(d,C)·R+└d/C┘
P2,d=mod(p1,d+NDVRB/2,NDVRB) [Expression 3]
On the other hand, if a DVRB index d is given, a PRB index can be derived using Expression 5.
On the other hand, in the method of
On the other hand, if a DVRB index d is given, a PRB index can be derived using Expression 11.
Again referring to the description given with reference to
As shown in
In order to solve this problem, the gap may be set to be a multiple of the number of RBs included in one RBG, namely, MRBG. That is, the gap may satisfy a condition “Gap=MRBG*k” (k is a natural number). When the gap is set to satisfy this condition, it may have a value of, for example, 27 (Gap=MRBG*k=3*9=27). When Gap=27, each DVRB may be divided into two parts, and a second one of the divided parts may be cyclically shifted by the gap (Gap=27). In this case, only a part of the resource elements of the RBG0, which consists of PRBs, are mapped by the first DVRB divided part, and only a part of the resource elements of the RBG9, which consists of PRBs, are mapped by the second DVRB divided part. Accordingly, in the method of
in the method of
In the case of
In the case of
In the case of
The problem occurs because the cyclic shift is performed such that a gap value does not equal to NDVRB/ND. When NDVRB/ND is a multiple of MRBG, the above-described problem is solved because the cyclic shift corresponds to a multiple of MRBG.
In order to simultaneously solve the problems of
Meanwhile, it can be seen that, in the above cases, the first and second divided parts of each DVRB belong to different subsets, respectively. In order to make the two divided parts of each DVRB belong to the same subset, the gap should be set to be a multiple of the square of MRBG (MRBG2).
Therefore, in another embodiment of the present invention, the number of RBs used for DVRBs, namely, NDVRB, is limited to a multiple of ND·MRBG2, in order to make the two divided parts of each DVRB belong to the same subset, and to make DVRBs be paired.
As shown in
When DVRB indexes are interleaved as shown in
Accordingly, in one embodiment of the present invention, the gap is set to be a multiple of MRBG, and the second divided part of each DVRB is cyclically shifted by NRB/ND so that the DVRB indexes mapped to one PRB are paired. Also, in order to avoid filling of nulls in the block interleaver, the number of RBs used for DVRBs, namely, NDVRB, is limited to a common multiple of ND·MRBG and D. If D is equal to the diversity order (NDivOrder=K·ND) used in the interleaver in this case, NDVRB is limited to a common multiple of ND·MRBG and K·ND.
In another embodiment of the present invention, the gap is set to be a multiple of the square of MRBG, in order to make the two divided parts of each DVRB be located on the same subset. Also, the second divided part of each DVRB is cyclically shifted by NRB/ND so that the DVRB indexes mapped to one PRB are paired. In order to avoid filling of nulls in the block interleaver, the number of RBs used for DVRBs, namely, NDVRB, is limited to a common multiple of ND·MRBG2 and D. If D is set to the diversity order (NDivOrder=K·ND) used in the interleaver in this case, NDVRB is limited to a common multiple of ND·MRBG2 and K·ND.
Meanwhile,
Of course, in the case of
In the embodiment of
In order to map the two divided parts of each DVRB to the PRBs in the same subset, the number of RBs used for DVRBs, namely, NDVRB, is limited to a common multiple of D·MRBG2 and ND·MRBG2. When D=K·ND, NDVRB is limited to K·ND·MRBG2 because the common multiple of K·ND·MRBG2 and ND·MRBG2 is K·ND·MRBG2.
Finally, the number of RBs used for DVRBs may be a maximum number of DVRBs satisfying the above-described limitations within the number of PRBs in the entire system. RBs used for DVRBs may be used in an interleaved manner.
Hereinafter, a mapping method using temporary PRB indexes when NPRB and NDVRB have different lengths in accordance with one embodiment of the present invention will be described.
One of the schemes shown by (a), (b), (c), and (d) of
In this case, four alignment schemes respectively illustrated in
[Expression 12]
Nthreshold=NDVRB/2, Noffset=NPRB−NDVRB (a):
Nthreshold=0, Noffset=0 (b):
Nthreshold=0, Noffset=NPRB−NDVRB (c):
Nthreshold=0, Noffset=└(NPRB=NDVRB)/2┐ or Noffset=┌(NRBG−NDVRB)/2┐ (d):
Here, (a) represents a justified alignment, (b) represents a left alignment, (c) represents a right alignment, and (d) represents a center alignment. Meanwhile, if a PRB index o is given, a DVRB index d can be derived from Expression 13, using a temporary PRB index p.
On the other hand, if the DVRB index d is given, a PRB index o can be derived from Expression 14, using a temporary PRB index p.
Hereinafter, a mapping method capable of increasing NDVRB to a maximum while satisfying the gap limitations in accordance with one embodiment of the present invention will be described.
The previous embodiments have proposed interleaver structures for reducing the number of PRBs, in which there are resource elements having parts not filled with DVRBs, where the RBG scheme and/or the subset scheme is introduced for allocation of LVRBs. The previous embodiments have also proposed methods for limiting the number of RBs used for DVRBs, namely,
However, as the limitation condition caused by MRBG becomes more strict, the limitation on the number of RBs usable for DVRBs, namely, NDVRB, among the total number of PRBs, namely, NPRB, increases.
When NDVRB is set to be a multiple of ND·MRBG2 (=18), to enable the two divided parts of each DVRB to be mapped to PRBs belonging to the same subset, while having a maximum value not exceeding the set NPRB, the set NDVRB is equal to 18 (NDVRB=18).
In order to enable the two divided parts of each DVRB to be mapped to PRBs belonging to the same subset in the case of
In this case, it can be seen that Ngap is 9 (Ngap=18/2=9), and the DVRB0 is mapped to respective first RBs of the RBG0 and RBG3 belonging to the same subset.
Accordingly, the present invention proposes a method for satisfying gap limitation conditions when ND=2 by setting an offset and a threshold value, to which the offset will be applied, as previously proposed, without directly reflecting the gap limitation conditions on NDVRB.
1) First, desired gap limitation conditions are set. For example, the gap may be set to a multiple of MRBG or a multiple of MRBG2.
2) Next, a numeral nearest to NPRB/2 among numerals satisfying the gap limitation conditions is set as Ngap.
3) When Ngap is smaller than NPRB/2, the same mapping as that of
4) When Ngap is equal to or larger than NPRB/2, and filling of nulls in the interleaver is allowed, NDVRB is set such that NDVRB=(NPRB−Ngap)·2. However, when no filling of nulls in the interleaver is allowed, NDVRB is set such that NDVRB=└min(NPRB−Ngap, Ngap)√2/C┐·C.
5) An offset is applied to a half or more of NDVRB. That is, a reference value for the application of the offset, namely, Nthreshold, is set such that Nthreshold=NDVRB/2.
6) The offset is set such that temporary PRBs, to which the offset is applied, satisfy the gap limitation conditions. That is, Noffset is set such that Noffset=Ngap−Nthreshold.
This may be expressed by Expression 15 as a generalized mathematic expression.
[Expression 15]
1. Setting of Ngap according to gap conditions:
2. Setting of NDVRB:
3. Setting of Nthreshold: Nthreshold=NDVRB/2
4. Setting of Noffset: Noffset: Noffset=Ngap−Nthreshold
When Ngap is set such that it is a multiple of MRBG2 (=9) while being nearest to NPRB/2, in order to map the two divided parts of each DVRB to PRBs belonging to the same subset, respectively, the set Ngap is equal to 18 (Ngap=18). In this case, 28 RBs ((32−18)×2=28) are used for DVRBs. That is, conditions of “NDVRB=28”, “Nthreshold=28/2=14”, and “Noffset=18−14=4” are established. Accordingly, temporary PRB indexes, to which DVRB indexes interleaved by the rectangular interleaver are mapped, are compared with Nthreshold. When Noffset is added to temporary PRB indexes satisfying Nthreshold, a result as shown in
Hereinafter, a mapping method capable of increasing NDVRB to a maximum while mapping consecutive indexes to specific positions in accordance with one embodiment of the present invention will be described.
Where one UE is allocated several DVRBs, the allocated DVRBs are consecutive DVRB. In this case, accordingly, it is preferable to set contiguous indexes such that they are positioned at intervals of a multiple of MRBG or a multiple of MRBG2, for scheduling of LVRBs, similarly to the setting of the gap. When it is assumed, in this case, that the degree of the interleaver is equal to the number of columns, namely, C, the number of rows, namely, R, should be a multiple of MRBG or a multiple of MRBG2. Accordingly, the size of the interleaver, namely, Ninterleaver=C·R, should be a multiple of C·MRBG or a multiple of C·MRBG2. Thus, if NDVRB is previously given, a minimum interleaver size satisfying the above conditions can be derived as follows.
Under no multiple condition, Ninterleaver=┌NDVRB/C┐·C.
In this case, accordingly, R=Ninterleaver/C=┌NDVRB/C┐.
Under the C·MRBG-multiple condition, Ninterleaver=┌NDVRB/(C·MRBG)┐·C·MRBG.
In this case, accordingly, R=Ninterleaver/C=┌NDVRB/(C·MRBG)┐·MRBG.
Under the C·MRBG2-multiple condition, Ninterleaver=┌NDVRB/(C·MRBG2)┐·C·MRBG2.
In this case, accordingly, R=Ninterleaver/C=┌NDVRB/(C·MRBG2)┐·MRBG2.
The number of nulls included in the interleaver is as follows.
Under no multiple condition,
Nnull=Ninterleaver−NDVRB=┌DVRB/C┐·C−NDVRB.
Under the C·MRBG-multiple condition,
Nnull=Ninterleaver−NDVRB=┌NDVRB/(C·MRBG)┐·C·MRBG−NDVRB.
Under the C·MRBG2-multiple condition,
NnullNinterleaver−NDVRB=┌NDVRB/(C·MRBG2)┐·C·MRBG2−NDVRB.
The exemplary embodiments described hereinabove are combinations of elements and features of the present invention. The elements or features may be considered selective unless otherwise mentioned. Each element or feature may be practiced without being combined with other elements or features. Further, the embodiments of the present invention may be constructed by combining parts of the elements and/or features. Operation orders described in the embodiments of the present invention may be rearranged. Some constructions of any one embodiment may be included in another embodiment and may be replaced with corresponding constructions of another embodiment. It is apparent that the present invention may be embodied by a combination of claims which do not have an explicit cited relation in the appended claims or may include new claims by amendment after application.
The embodiments of the present invention may be achieved by various means, for example, hardware, firmware, software, or a combination thereof. In a hardware configuration, the embodiments of the present invention may be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.
In a firmware or software configuration, the embodiments of the present invention may be achieved by a module, a procedure, a function, etc. performing the above-described functions or operations. A software code may be stored in a memory unit and driven by a processor. The memory unit is located at the interior or exterior of the processor and may transmit data to and receive data from the processor via various known means.
The present invention is applicable to a transmitter and a receiver used in a broadband wireless mobile communication system.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
Ahn, Joon Kui, Kim, Eun Sun, Kim, Bong Hoe, Seo, Dong Youn
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