WO2007094628A1

WO2007094628A1 - Method and apparatus for resource allocation in an ofdm system

Info

Publication number: WO2007094628A1
Application number: PCT/KR2007/000815
Authority: WO
Inventors: Young-Bum Kim; Hwan-Joon Kwon; Ju-Ho Lee
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2006-02-15
Filing date: 2007-02-15
Publication date: 2007-08-23
Also published as: KR20070082569A; KR100894142B1

Abstract

An apparatus and method for allocating a radio resource using a localized transmission scheme and a distributed transmission scheme in combination in an orthogonal frequency division multiple access system. The present invention provides a scheme of allocating radio resources using the localized transmission scheme and the distributed transmission scheme together in an OFDM system. In addition, the present invention allocates radio resources to each terminal according to the distributed transmission scheme taking into account traffic type and channel status of the terminal. That is, the present invention maps and allocates multiple distributed virtual resource blocks to physical resource blocks having a predetermined size on a scattered basis, thereby allowing a corresponding terminal to maximize frequency diversity gain for the transmitted data.

Description

METHQD AND APPARATUS FOR RESOURCE ALLOCATION IN AN

OFDM SYSTEM

Brief Description of the Drawings FIG. 1 is a diagram illustrating an example of an OFDM system using a general localized transmission scheme.

FIG. 2 is a diagram illustrating an example of an OFDM system using a general distributed transmission scheme.

FIG. 3 is a diagram illustrating an example of mapping Virtual Resource Blocks (VRB) to Physical Resource Blocks (PRB).

FIG. 4 is a diagram illustrating a mapping relationship between VRBs and PRBs according to a first embodiment and a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a mapping relationship between VRBs and PRBs according to a third embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of radio resource mapping to which a distributed transmission scheme is applied according to a fourth embodiment of the present invention.

FIG. 7 is a diagram illustrating an example of radio resource mapping to which a distributed transmission scheme is applied according to a fifth embodiment of the present invention.

FIG. 8 is a diagram illustrating a transmission apparatus according to a preferred embodiment of the present invention.

FIG. 9- is a diagram illustrating a reception apparatus according to a preferred embodiment of the present invention.

Detailed Description of the Invention

Object of the Invention

Technical Field and Related Prior Arts of the Invention The present invention relates generally to a communication system using a multiple access scheme, and in particular, to a method and apparatus for allocating radio resources in a communication system that transmits/receives data based on orthogonal frequency division multiplexing scheme. Recently, in a mobile communication system, active research is being conducted on an Orthogonal Frequency Division Multiplexing (OFDM) scheme which is useful for high-speed data transmission in wire/wireless channels.

The OFDM scheme, a scheme for transmitting data using multiple carriers, is a kind of Multi-Carrier Modulation (MCM) scheme that converts a serial input symbol stream into parallel symbol streams and modulates each of them with a plurality of orthogonal sub-carriers, i.e. sub-carrier channels, before transmission.

The OFDM scheme has the following advantages.

The OFDM scheme has high frequency utilization efficiency, as it maintains orthogonality between sub-carriers during transmission, and overlaps frequency spectrums.

In addition, the OFDM scheme, as it is robust against multi-path fading, can obtain optimal transmission efficiency during high-speed data transmission.

Further, the OFDM scheme is robust against frequency selective fading, can reduce an Inter-Symbol Interference (ISI) effect with use of a guard interval, and can facilitate simple hardware design of an equalizer.

Moreover, the OFDM scheme, as it is robust against impulse noises, is now actively used for communication system architecture.

In wireless communication, the high-speed, high-quality data service is generally impeded by the channel environment. In the wireless communication, the channel environment is subject to frequent change due to a change in power of a received signal, caused by fading as well as Additive White Gaussian Noise (AWGN), shadowing, a Doppler effect caused by movement of a terminal and a frequent change in its velocity, interference from other users and multi-path signals, and the like. Therefore, the wireless communication needs to effectively cope with the foregoing issues in order to support the high-speed, high-quality data service.

In this context, in the OFDM system, the following transmission schemes and techniques are now proposed as a scheme for overcoming the fading.

The proposed schemes include a localized transmission scheme and a distributed transmission scheme.

The localized transmission scheme will first be described.

The localized transmission scheme is an Adaptive Modulation and Coding (AMC) scheme that adaptively adjusts a modulation scheme and a coding scheme according to a channel change of a downlink. Generally, the channel change of a downlink, i.e. Channel Quality Information (CQI), can be detected at a user terminal, which is a reception apparatus, by measuring a Signal-to-Noise Ratio (SNR) of a received signal. In addition, the terminal feeds back the measured downlink CQI to a base station through an uplink. Accordingly, the base station estimates channel status of the downlink using the downlink CQI fed back from the terminal, and adjusts the modulation scheme and the coding scheme according to the estimated channel status.

Therefore, the localized transmission scheme generally applies a high- order modulation scheme and a high coding rate for a better channel status, and applies a low-order modulation scheme and a low coding rate for a worse channel status.

The localized transmission scheme, compared with the existing fast power control-based transmission scheme, increases adaptability to the channel variation, thereby improving the average system performance. The localized transmission is also called 'block- wise transmission'.

FIG. 1 illustrates an example of a general OFDM system using the localized transmission scheme.

Referring to FIG. 1, the horizontal axis indicates a time axis, and the vertical axis indicates a frequency axis. Reference numeral 101 indicates one sub-carrier, and reference numeral 102 one OFDM symbol.

Generally, the OFDM system using localized transmission divides the full frequency band into N sub-carrier groups, and performs AMC on each sub- carrier group independently. In addition, scheduling is performed in units of multiple OFDM symbols, as shown by reference numeral 105.

Therefore, one sub-carrier group is called one resource block (RB). The RB is composed of X consecutive sub-carriers and Y consecutive OFDM symbols, and its size is XxY. In FIG. 1, a sub-carrier group #1 103 is called an RB # 1, and a sub-carrier group #N 104 is called an RB #N. As described above, the OFDM system has a plurality of RBs and performs an AMC operation separately for each individual RB.

Therefore, each terminal feeds back CQI information separately for each RB, and a base station receives CQI for a corresponding RB from each terminal, performs scheduling for each RB, and transmits user data separately for each RB. Therefore, the base station scheduling selects a terminal having the highest channel quality and transmits data thereto separately for each RB, thereby maximizing the system capacity.

In the AMC operation, it is preferable that sub-carriers necessary for transmitting data for one terminal are adjacent to each other, for the following reason. When frequency selectivity occurs in a frequency domain due to a multi- path wireless channel, sub-carriers being adjacent to each other are similar in strength of a channel response, but sub-carriers being spaced apart from each other can be considerably different in strength of the channel response. Therefore, the AMC operation gathers sub-carriers having a good channel response and transmits data through them, thereby maximizing the system capacity. As a result, the localized transmission technique is suitable for data transmission to a specific user. This is because it is not preferable that the channels transmitted to a plurality of users, for example, broadcast channels or common control information channels, are adapted to a channel status of a certain user.

In addition, the localized transmission technique is suitable for transmission of data traffics which are less susceptible to transmission delay, for the following reason. That is, because the localized transmission technique is a scheme for basically selecting terminals in a good channel status and allowing them to transmit data, the traffics susceptible to delay, for example, the real-time traffics such as Voice over IP (VoIP) or video conference traffics, cannot be waited by the corresponding user infinitely until the channel status becomes good. That is, for the users servicing the real-time traffics, in order to secure the limit in the delay, it is necessary to transmit data to the corresponding user even in a poor channel status.

According to the foregoing description, the localized transmission technique is unsuitable for the traffics that should not be adapted to a channel environment of a specific user, such as broadcast channels or common control channels, or for the traffics susceptible to delay, such as the real-time traffics. A description will now be made of a transmission scheme suitable for the real-time traffics and the traffics using the broadcast and common channels.

Generally, a wireless channel is subject to change even in the time axis, and undergoes a repetitive phenomenon in which the channel is good in a partial frequency domain, and bad in the other partial frequency domain. In this channel environment, if it is not possible to transmit data in adaptation to a channel of a specific user, it is unavoidable from the standpoint of each terminal that the transmitted data is received in a good channel status sometimes, and received in a bad channel status sometimes. A technique suitable for such environments or traffics is a distributed transmission technique.

That is, the distributed transmission technique aims at allowing the transmission data to experience good channels and bad channels as uniformly as possible. The reason is as follows. If specific transmission data, for example, one specific data packet, is received in a bad channel status, the packet can hardly be demodulated successfully. However, in terms of the reception performance, if modulation symbols included in one packet have symbols experiencing bad channels and symbols experiencing good channels, it is possible to demodulate the packet for the symbols in the bad channel status, using the symbols experiencing the good channels. The distributed transmission is also called 'scattered transmission'.

FIG. 2 illustrates an example of transmitting user data or common control information using the distributed transmission technique in a general OFDM system.

In FIG. 2, a base station intends to transmit data to three terminals (for example, Mobile Stations (MSs) or User Equipments (UEs)), i.e. MS l , MS2 and MS3. It can be noted that as the data is transmitted with the distributed transmission scheme, the data transmitted to one terminal is scattered in the frequency domain and the time domain.

Data symbols for the MS l, transmitted for an OFDM symbol 201, are occupying three sub-carriers. It is general to scatter sub-carriers for each terminal over the full band in order to obtain frequency diversity gain in the frequency domain. In addition, positions of specific sub-carriers for the terminal are agreed between the base station and the terminal. Further, it can be noted that positions of symbols transmitted to the MSl for an OFDM symbol interval 201 are different from positions of symbols transmitted to the MSl for an OFDM symbol interval 202.

In order to maximize an effect of time diversity gain in the time axis, a transmission apparatus determines whether to transmit data symbols through different sub-carriers every OFDM symbol or every predetermined unit time. This is generally called 'frequency hopping', and the OFDM system applying the diversity technique applies the frequency hopping technique together. As described above, the OFDM communication system uses the localized transmission technique and the distributed transmission technique, which are the two possible transmission schemes for overcoming the fading. The transmission techniques contrast with each other in their characteristics, and are different even in type of the traffics suitable thereto.

In this context, the current mobile communication system intends to propose a scheme for appropriately operating the transmission schemes in combination, instead of applying only one of the transmission techniques. That is, there is a need for a new transmission scheme capable of maximizing frequency diversity gain, while minimizing fading of a user terminal.

Technical Subject of the Invention

An aspect of the present invention is to address at least the problems and/or disadvantages and to provide at least the advantages described below.

Accordingly, an aspect of the present invention is to provide a method and apparatus for mapping radio resources by adaptively applying a localized transmission scheme and a distributed transmission scheme in an OFDM system.

Another aspect of the present invention is to provide a method and apparatus for mapping radio resources to a physical channel using a distributed transmission scheme in a mobile communication system.

Another aspect of the present invention is to provide a method and apparatus for demapping radio resources by adaptively applying a localized transmission scheme and a distributed transmission scheme in an OFDM system.

Another aspect of the present invention is to provide a method and apparatus for demapping radio resources using a distributed transmission scheme in a mobile communication system.

According to one aspect of the present invention, there is provided a method for allocating a radio resource of a transmission apparatus in an orthogonal frequency division multiple access system. The method includes determining a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel, and a number J of distributed virtual resource blocks (VRBs) to be used for a distributed transmission scheme; determining a parameter K indicating an interval between the distributed VRBs using the I and the J; sequentially mapping the J distributed VRBs to J first PRBs having an interval of the K, among the I PRBs; mapping localized VRBs to be used for a localized transmission scheme, to the remaining (I-J) second PRBs except for the first PRBs, among the I PRBs; and allocating the PRBs to at least one terminal according to a transmission scheme of the corresponding mapped VRBs.

According to another aspect of the present invention, there is provided a method for allocating a radio resource in an orthogonal frequency division multiple access system. The method includes determining a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel, and a number J of distributed virtual resource blocks (VRBs) to be used for a distributed transmission scheme, wherein the PRB and the VRB have K and L sub-carriers, respectively; sequentially mapping the J distributed VRBs to first PRBs having an interval of the K among the I PRBs; mapping sub-carriers of the distributed VRBs to sub-carriers of the first PRBs so that sub-carriers having an interval of the L among the sub-carriers constituting the J distributed VRBs are mapped to adjacent sub-carriers in the first PRBs; mapping localized VRBs to be used for a localized transmission scheme to the remaining (I-J) second PRBs except for the first PRBs among the I PRBs; and allocating the PRBs to at least one terminal according to a transmission scheme of the corresponding mapped VRBs.

According to further another aspect of the present invention, there is provided an apparatus for allocating a radio resource in an orthogonal frequency division multiple access system. The apparatus includes a scheduler for determining a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel and has K sub-carriers, and a number J of distributed virtual resource blocks (VRBs), each of which is to be used for a distributed transmission scheme and has L sub-carriers, sequentially mapping the J distributed VRBs to first PRBs having an interval of the K among the I PRBs, mapping sub-carriers of the distributed VRBs to sub-carriers of the first PRBs so that sub-carriers having an interval of the L among the sub-carriers constituting the J distributed VRBs are mapped to adjacent sub-carriers in the first PRBs, and mapping localized VRBs to be used for a localized transmission scheme to the remaining (1-J) second PRBs except for the first PRBs among the I PRBs; and a mapper for allocating the PRBs to at least one terminal according to a transmission scheme of the corresponding mapped VRBs.

According to yet further another aspect of the present invention, there is provided a method for receiving an allocated radio resource in an orthogonal frequency division multiple access system. The method includes receiving, through signaling, a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel, and a number J of distributed virtual resource blocks (VRBs) to be used for a distributed transmission scheme, wherein the PRB and the VRB have K and L sub-carriers, respectively; acquiring from first PRBs the J distributed VRBs which are sequentially mapped to the first PRBs having an interval of the K among the I PRBs, wherein sub- carriers of the distributed VRBs are mapped to sub-carriers of the first PRBs so that sub-carriers having an interval of the L among the sub-carriers constituting the .1 distributed VRBs are mapped to adjacent sub-carriers in the first PRBs; acquiring localized VRBs mapped to be used for a localized transmission schemes from the remaining (I-J) second PRBs except for the first PRBs among the I PRBs; and acquiring transmission data according to a transmission scheme of the corresponding mapped VRBs of the PRBs.

According to still further another aspect of the present invention, there is provided a reception apparatus for receiving an allocated radio resource in an orthogonal frequency division multiple access system. The apparatus includes a demapper for receiving, from a transmission apparatus through signaling, a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel, and a number J of distributed virtual resource blocks (VRBs) to be used for a distributed transmission scheme, wherein the PRB and the VRB have K and L sub-carriers, respectively, acquiring from first PRBs the J distributed VRBs which are sequentially mapped to the first PRBs having an interval of the K among the I PRBs, wherein sub-carriers of the distributed VRBs are mapped to sub-carriers of the first PRBs so that sub-carriers having an interval of the L among the sub-carriers constituting the J distributed VRBs are mapped to adjacent sub-carriers in the first PRBs, and acquiring localized VRBs mapped to be used for a localized transmission schemes from the remaining (I-J) second PRBs except for the first PRBs among the 1 PRBs; a demodulator for demodulating the PRBs according to a transmission scheme of the corresponding mapped VRBs; and a decoder for decoding transmission data of the demodulated PRBs.

Construction and Operation of the Invention

The operation principle of the present invention will now be described in detail with reference to the annexed drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for clarity and conciseness. The terms used herein are defined taking into account their functions in the present invention, and are subject to change according to user, user's intention, or practice. Therefore, the definitions should be made based on the entire contents of the specification.

The present invention provides a scheme for adaptively applying a localized transmission scheme and a distributed transmission scheme according to characteristic of traffics in an OFDM-based communication system, thereby allocating radio resources using the two schemes together. More specifically, the present invention proposes a scheme for allocating radio resources to each terminal according to a distributed transmission scheme taking into account traffic type and channel status of each terminal.

That is, for the case where a localized transmission scheme and a distributed transmission scheme are used together, the present invention proposes a detailed scheme for mapping the resources corresponding to each of the transmission schemes to a physical channel. In addition, the present invention proposes a detailed scheme for mapping resources corresponding to the distributed transmission scheme to a physical channel, i.e. physical resource blocks.

Definitions of the terms used herein are given below.

■ Physical Resource Block (PRB): PRB, a mapping unit of allocated resources, is composed of M consecutive sub-carriers and N consecutive OFDM symbols, and its size is MxN. Generally, the N OFDM symbols constitute one sub-frame.

■ Virtual Resource Block (VRB): VRB is divided into a localized VRB and a distributed VRB according to transmission scheme in units of virtual resource allocation before resources are actually mapped in the time/frequency domains.

- Localized Virtual Resource Block (LVRB): During localized transmission, a localized VRB is mapped to the PRB on a 'localized' basis.

- Distributed Virtual Resource Block (DVRB): During distributed transmission, a distributed VRB is mapped to the PRB on a 'distributed' basis.

For convenience, a size of every resource block is considered in the frequency domain. In addition, through extension to the time domain, the size of the resource block can be expressed in the 2-dimensional time/frequency domain.

In addition, in base station scheduling according to the present invention, each terminal feeds back CQI information over an uplink separately for one PRB or a plurality of PRBs, and based on the CQI feedback information, a base station acquires CQI for each PRB of the terminal. Thereafter, the base station performs scheduling on each PRB to allocate each PRB to the terminal, and transmits user data using the allocated PRB. The base station can use the localized transmission scheme and the distributed transmission scheme in combination in order to improve the system performance. That is, for every PRB, the base station can determine whether it will perform localized transmission or distributed transmission. In this case, for data reception, the terminal should correctly know a type of the transmission scheme for each PRB. Therefore, there is a need for signaling corresponding to the transmission scheme. If a transmission scheme for each PRB follows a predefined rule, signaling overhead between the terminal and the base station can be reduced. A description will now be made of a rule for determining, a VRB of which transmission scheme it will map to each PRB, according to an embodiment of the present invention.

First, the base station determines the total number I of PRBs and the total number J of distributed VRBs.

Herein, an index indicating a position of each PRB can be denoted by i =

0, •••, 1-1 , and an index indicating each distributed VRB can be denoted by j = 0, •••, .1- 1. The total number I of PRBs is predetermined taking the system band into account, or determined by the base station, and information thereon can be provided to the terminals through signaling. The total number of distributed VRBs and the total number of localized VRBs can be determined by a base station scheduler taking into account a desired transmission traffic type, CQI feedback information from a terminal, etc., or predetermined values can be used as the total number of distributed VRBs and the total number of localized VRBs.

In addition, a parameter K indicating an interval between the distributed

VRBs mapped to the PRBs is determined using Equation ( 1 ), in which [xj

means a maximum integer not exceeding 'x\ From the foregoing definitions, a distance between distributed VRBs mapped on the PRBs on a scattered basis within the total number I of PRBs is a maximum of K-I .

/ - 1

K = (i)

J - i

Finally, positions L of the PRBs to which the distributed VRBs are mapped are determined using Equation (2).

L = \L L₁ = J x K] (2) Positions other than the positions L determined using Equation (2) are PRBs to which the localized VRBs can be mapped.

FIG. 3 illustrates a concept of mapping individual PRBs using different transmission schemes according to the present invention.

Referring to FIG. 3, the horizontal axis indicates a frequency axis.

Reference numeral 301 indicates a PRB that a base station has allocated for localized transmission, and reference numeral 303 indicates a PRB that the base station has allocated for distributed transmission and a distributed VRB is actually mapped thereto.

In the following description, it is assumed that the total number of the

PRBs is 1=10 and the total number of the distributed VRBs is J=3. Thus, an index 'i' indicating each of the PRBs can be i = 0, 1, •••, 9 (=1-1), and an index 'j' indicating each of the distributed PRBs can be j = 0, 1, 2 (⁼J-1). Therefore, a parameter K indicating an interval between the distributed VRBs mapped to the

/ - 1 10 - 1

PRBs is defined as ^ = = 4. Finally, positions L of the PRBs to J - I 3 - 1 which the distributed VRBs are mapped are L = [L₁ L₁ = 7 x Aj= {0,4,8} , and

positions of the PRBs to which the localized VRBs can be mapped are { 1, 2, 3, 5, 6, 7, 9} except for {0, 4, 8} .

As described above, the present invention defines an interval between the distributed VRBs mapped to the PRBs, and defines a distributed transmission mapping rule according thereto. To acquire information on the resource mapping positions of the base station, a corresponding terminal needs the total number I of PRBs and the total number J of distributed VRBs, or their equivalent values. Therefore, the base station signals, to the terminal, information used for calculating an interval between the distributed VRBs mapped to the PRBs, so that both the base station and the terminal can calculate correct mapping positions of the VRBs which are distributed-transmitted on the PRBs according to the common rule. The signaling can be physical layer signaling or upper layer signaling.

In the multi-cell environment, the mapping rule based on Equation (1) and Equation (2) may cause degradation of the system performance. This is because if all cells use the same foregoing mapping rule, a VRB is mapped to a position of the same PRB for every cell, causing intercell interference at the corresponding PRB.

Therefore, the present invention provides a scheme for avoiding intercell interference by changing positions L of the PRBs to which the distributed VRBs are mapped, using Equation (3).

L = IL L₁ = (/ x K + offseήmod 1) (3)

where 'x mod y' means a remainder obtained by dividing 'x' by 'y', and 'offset' is a unique value for each cell, and can be, for example, a cell ID.

Application of the mapping rule will now be described in detail with reference to a first embodiment, a second embodiment, and a third embodiment.

First Embodiment

A VRB-to-PRB mapping rule for avoiding the intercell interference can be defined as follows.

The total number I of PRBs and the total number J of distributed VRBs are determined. An index indicating a position of each PRB can be indicated by i = 0, ^•••, 1-1 , and an index indicating a position of each VRB can be indicated by j = 0, — , J- I .

The total number of PRBs can be predetermined taking the system band into account, or can be determined by the base station and then notified to terminals through signaling. The total number of distributed VRBs and the total number of localized VRBs can be determined by a base station scheduler taking into account a desired transmission traffic type, CQI feedback information of terminals, etc, or predetermined values can be used as the total number of distributed VRBs and the total number of localized VRBs.

A parameter K indicating an interval between the distributed VRBs mapped to the PRBs is determined using Equation (1).

Finally, positions L of the PRBs to which the distributed VRBs are mapped are determined using Equation (3). PRB positions other than the determined positions L are PRBs to which the localized VRBs can be mapped.

FlG. 4 illustrates a detailed example to which a mapping rule is applied according to first and second embodiments of the present invention.

Referring to FIG. 4, the horizontal axis indicates the frequency axis. Reference numeral 401 indicates a PRB that the base station has allocated for localized transmission, and reference numerals 403, 405 and 407 indicate PRBs that the base station has allocated for distributed transmission and distributed

VRBs are actually mapped thereto.

Assume that there are a total of 3 cells of cell #0, cell # 1 and cell #2, and offsets of the cells are 0, 1 and 2, respectively. For convenience, FIG. 4 considers mapping of only the distributed VRBs.

It is assumed in FIG. 4 that in each cell, the total number of PRBs is I= IO and the total number of distributed VRB is J=3. An index T indicating each of the PRBs can be i = 0, 1, ••^■, 9 (=1-1), and an index 'j' indicating each of the distributed PRBs can be j = 0, 1, 2 (=J-1).

Accordingly, a parameter K indicating an interval between the

/ - 1 I I l o - i distributed VRBs mapped to the PRBs is K = = 4 . For each cell

_.J - ij L 3 — 1 with a unique intercell offset, positions L of the PRBs to which the distributed VRBs are mapped can be calculated as follows. In cell #0, positions L of the PRBs to which the distributed VRBs are mapped are calculated as {0, 4, 8} by Equation (3) (see reference numeral 409). In cell #1 , positions L of the PRBs to which the distributed VRBs are mapped are calculated as { 1, 5, 9} (see reference numeral 41 1). In cell #2, positions L of the PRBs to which the distributed VRBs are mapped are calculated as {0, 2, 6} (see reference numeral 413).

For each cell, positions of the PRBs to which the localized VRBs are mapped are the remaining positions except for the determined positions L. That is, in cell #0, the localized VRBs are mapped to the PRBs in the positions of { 1, 2, 3, 5, 6, 7, 9} . In cell #1 , the localized VRBs are mapped to the PRBs in the positions of {0, 2, 3, 4, 6, 7, 8} . In cell #2, the localized VRBs are mapped to the PRBs in the positions of { 1 , 3, 4, 5, 7, 8, 9} .

As described above, the present invention defines positions L of the PRBs to which the distributed VRBs are mapped, for each cell. As shown by reference numerals 409 and 411, a distance at which the distributed VRBs are distributed on the PRBs on a scattered basis within the total number 1=10 of PRBs is maximized to K- 1=3, thereby increasing a frequency diversity effect for each individual terminal for the distributed VRBs.

However, as to the PRB allocation for cell #2, shown by reference numeral 413, a characteristic of the parameter K indicating an interval between the distributed VRBs is lost due to the 'mod' calculation. That is, as the base station, after allocating a 2^nd PRB, allocates a 6^th PRB and then allocates a 0^th PRB with 4 PRB intervals, the interval K is not maintained between the θ"' PRB and the 2^nd PRB. In addition, some positions in which the distributed VRBs of cell #0 and cell #2 are mapped to the PRBs are mapped to the same PRB of the 0^th PRB of each cell, causing intercell interference between cell #0 and cell #2.

Therefore, additional restriction can be applied to the mapping rule in order to maintain the characteristic of maximizing the distance at which the distributed VRBs are mapped on the PRBs on a scattered basis.

The following second embodiment is provided to solve this problem. Second Embodiment

The second embodiment restricts only the L for allowing all elements of a set L in the rule of Equation (3) to be less than I, to the positions in which the distributed VRBs are mapped on the PRB on a scattered basis. For convenience, this will be referred to herein as 'Condition 1 '.

That is, in order to prevent the mapping 413 from occurring in the first embodiment, the second embodiment adds Condition 1 to the mapping rule defined in the first embodiment, thereby newly defining L. Therefore, the rule for L is changed as follows.

That is, the new L is defined by L = [L₁ L₁ = j x K) and its shifted values,

and this can be expressed as Equation (4).

L_m

= j x K + _m, L_l,m < I), /π = 0,l,Λ (4)

where m is a value indicating a shifted value of the L, and there is a relationship of L() = L.

Condition 1 is satisfied by defining a relationship of Equation (5) between the m and a unique offset for each cell.

m = offset mod{/ - K - [J - X)) (5)

In this manner, it is possible to maintain the characteristic of maximizing the distance at which the distributed VRBs are mapped on the PRBs on a scattered basis. As a result, for the distributed VRBs, it is possible to increase a frequency diversity effect between cells.

In this case, however, intercell interference may increase.

In the second embodiment, each cell is restricted to have one of L₀=(O, 4, 8} and L₁=( I , 5, 9} as the L. That is, for cell #2 or the 3^rd cell, the distributed VRBs are configured according to the defined mapping rule, as shown by reference numeral 409 for cell #0 or the 1^st cell.

Third Embodiment The third embodiment, unlike the first and second embodiments, proposes another mapping rule aiming at reducing an intercell interference effect, instead of aiming at maximizing the distance at which the distributed VRBs are mapped on the PRBs on a scattered basis.

The total number I of PRBs and the total number J of distributed VRBs are determined.

An index indicating a position of each PRB can be denoted by i = 0, •••, I- 1 , and an index indicating a position of each distributed VRB can be denoted by j = 0, •••, J-I . The total number of PRBs can be predetermined taking the system band into account, or can be determined by the base station and then notified to terminals through signaling. The total number of distributed VRBs and the total number of localized VRBs can be determined by a base station scheduler taking into account a desired transmission traffic type, CQI feedback information of terminals, etc, or predetermined values can be used as the total number of distributed VRBs and the total number of localized VRBs.

A parameter K indicating an interval between the distributed VRBs can be determined using Equation (6).

^' /

K = (6)

J where |_xj means a maximum integer not exceeding 'x'.

Finally, positions L of the PRBs to which the distributed VRBs are mapped can be determined using Equation (3), as described above. PRB positions other than the determined positions L are PRBs to which the localized VRBs can be mapped. FIG. 5 illustrates a detailed example according to the third embodiment of the present invention.

Referring to FIG. 5, the horizontal axis indicates the frequency axis. Reference numeral 501 indicates a PRB that the base station has allocated for localized transmission, and reference numerals 503, 505 and 507 indicate PRBs that the base station has allocated for distributed transmission and the distributed

VRBs are mapped thereto. Assume that there are a total of 3 cells of cell #0, cell

#1 and cell #2, and offsets of the cells are 0, 1 and 2, respectively. For convenience, FIG. 5 considers mapping of only the distributed VRBs.

It is assumed in FIG. 5 that in each cell, the total number of PRBs is 1=10 and the total number of distributed VRB is J=3. An index 'i' indicating each of the PRBs can be i = 0, 1, •••, 9 (=1-1), and an index 'j' indicating each of the distributed PRBs can be j = 0, 1 , 2 (=J- 1 ).

H)

Accordingly, the parameter K is K = = 3 according to

3

Equation (6). For each cell with a unique offset, positions L of the PRBs to which the distributed VRBs are mapped can be calculated as follows. In cell #0, positions L are {0, 3, 6} by Equation (3) (see reference numeral 409). In cell #1, positions L are { 1, 4, 7} (see reference numeral 41 1). In cell #2, positions L are {2, 5, 8} (see reference numeral 413).

Therefore, positions in which the localized VRBs can be mapped to the PRB are the remaining positions except for the determined positions L, for each cell. That is, in cell #0, the localized VRBs are mapped to the PRBs in the positions of { 1, 2, 4, 5, 7, 8, 9} . In cell # 1, the localized VRBs are mapped to the PRBs in the positions of {0, 2, 3, 5, 6, 8, 9} . In cell #2, the localized VRBs are mapped to the PRBs in the positions of {0, 1, 3, 4, 6, 7, 9} .

As described above, positions L of the PRBs to which the distributed VRBs mapped are defined. As shown by reference numerals 509, 51 1 and 513, a distance at which the distributed VRBs are distributed on the PRBs on a scattered basis within the total number 1=10 of PRBs is maintained at K- 1=2.

When the mapping rule according to the third embodiment is applied, compared with when the first embodiment and the second embodiment are applied under the same assumption, the maximum distance at which the distributed VRBs are mapped on the PRBs on a scattered basis decreases from 3 to 2 by 1, but the distance is maintained at 2 in any cell, thereby contributing to a reduction in the intercell interference effect.

To sum up, the third embodiment, compared with the first embodiment or the second embodiment, has a shorter interval at which the distributed VRBs are mapped on the PRBs on a scattered basis, but has no intercell interference, contributing to an increase in reception performance of terminals.

A description will now be made of a fourth embodiment and a fifth embodiment, in which specific distributed VRBs are mapped to PRJBs.

Fourth Embodiment

The base station first determines the total number I of available PRBs and the total number J of distributed VRBs. An index indicating a position of each PRB can be denoted by i = 0, •••, 1-1, and an index indicating a position of each distributed VRB can be denoted by j = 0, •••, J- I .

The number of PRBs is predetermined according to the system band, or can be determined by the base station and then notified to terminals through signaling. The number of distributed VRBs and the number of localized VRBs can be determined by a base station scheduler taking into account a desired transmission traffic type, CQI feedback information from terminals, etc., or predetermined values can be used as the number of distributed VRBs and the number of localized VRBs.

The PRBs and the distributed VRBs can be subdivided into smaller unit blocks. If an index indicating each of the small resource blocks constituting the PRB is denoted by k = 0, 1, ••■, k- 1 and an index indicating each of the small resource blocks constituting the distributed VRB is denoted by 1 - 0, 1 , •••, 1- 1 , then a k"¹ small resource block in the i^th PRB is denoted by PRB_{1 k} and an 1^th small resource block in the j^th distributed VRB is denoted by DVRB, ,.

The scheduler determines to which PRBs it will map the distributed

VRBs and the localized VRBs according to a predefined rule.

The index i is determined depending on the predefined rule as a rule for mapping the DVRB_1J to the PRB₁^ allocated for distributed VRBs, and for each i, DVRB_1J is mapped to a k^th small resource block as follows.

■ For a first PRB_Iik (=DVRB,,₀) allocated for distributed VRBs DVRB,o => PRB,,_k ( j = k=O, l , -)

■ For a second PRB_{1 k} C=DVRB_1,,) allocated for distributed VRBs

DVRB₁,, => PRB,,_k ( j = k=0, 1, -)

■ For a third PRB,,_k (=DVRB,,₂) allocated for distributed VRBs DVRB,,₂ => PRB₁,_k ( j = k=0, 1, ^•••)

In this rule, up to the last PRB,_,k allocated for distributed VRBs is mapped to small resource blocks of the distributed DVRB.

FIG. 7 is a diagram illustrating how to map distributed VRBs to PRBs allocated for distributed VRBs according to the predefined rule.

In FIG. 6, the horizontal axis indicates a frequency axis, reference numeral 601 indicates distributed VRBs allocated for distributed transmission by the base station, and reference numeral 605 indicates all PRBs available by the base station. Herein, it is shown that the distributed VRBs are mapped to 0^th, 4^th and 8^th PRBs. For convenience, mapping of only the distributed VRBs are considered herein. In FIG. 6, assuming that the total number of PRBs is 1=10 and the total number of distributed VRBs is J=3, the PRB and the distributed VRB are composed of k=3 and 1=3 small resource blocks, respectively. Accordingly, indexes indicating the PRBs are i = 0, 1 , ^••• , 9 (= I - 1) and k=0, 1, 2 (=k-l). In addition, indexes indicating the distributed VRBs are j = 0, 1 , 2 (W - 1 ) and 1 - 0, 1, 2 (=1- 1 ).

Therefore, as shown in FlG. 6, the results obtained by mapping the

DVRBjj to the PRB; , allocated for distributed VRBs according to the predefined rule are

PRB_0-0 = DVRBo.o, PRB₀,, = DVRB ,,₀, PRB₀,₂ = DVRB₂,₀, PRB₄,o = DVRB₀, i , PRB₄, , = DVRB _u , PRB₄,₂ = DVRB₂, i , PRB_{8 0} = DVRBo,₂, PRB_8J = DVRB ,,₂, PRB₈,₂ = DVRB_{2 2}

By defining the foregoing mapping rule, the information that the terminal needs in order to detect resource mapping positions of the base station needs the total number J of distributed VRBs and the total number 1 of small resource blocks in the distributed VRB, or their equivalent values.

Therefore, as the base station signals information on the numbers to the terminal, both the base station and the terminal can calculate the accurate mapping position of each distributed VRB on the PRB according to the common rule. The signaling can be physical layer signaling or upper layer signaling.

However, the mapping rule shown in FIG. 6 for subdividing a PRB composed of M consecutive sub-carriers into k small resource blocks and mapping them to the distributed VRBs has the following disadvantage. If an integer ratio between M and k is satisfied, the k small resource blocks are all maintained equal to M/k in size. However, if the integer ratio between M and k is not satisfied, the k small resource blocks are not maintained equal to each other in size.

Therefore, it is hard to generalize the mapping rule for mapping the distributed VRBs to the k small resource blocks, thereby causing an increase in complexity and requiring additional signaling overhead corresponding thereto.

In order to solve this problem, the present invention proposes a scheme for reducing the signaling overhead, and subdividing the PRB composed of M consecutive sub-carriers into k small resource blocks, thereby simplifying a mapping relationship between the distributed VRBs.

Fifth Embodiment

FlG. 7 illustrates another method for mapping distributed VRBs to PRBs according to the present invention.

First, the base station determines the total number I of available PRBs and the total number J of distributed VRBs. An index indicating a position of each PRB can be denoted by i = 0, •••, 1-1 , and an index indicating a position of each distributed VRB can be denoted by j = 0, •••, J-I . The total number of PRBs is predetermined taking system band into account, or can be determined by the base station and then notified to the terminals through signaling.

The total number of distributed VRBs and the total number of localized

VRBs can be determined by a base station scheduler taking into account a transmission traffic type, CQI feedback information from a terminal, etc., or predetermined values can be used as the total number of distributed VRJBs and the total number of localized VRBs.

The PRBs and the distributed VRBs can be subdivided into smaller unit resource blocks. If an index indicating each of the small resource block constituting the PRB is denoted by k = 0, 1 , •^■•, k-1 and an index indicating each of the small resource block constituting the distributed VRB is denoted by 1 = 0, 1, •••, L- I , then a k^th small resource block in the i^th PRB is denoted by PRB_{1 k} and an 1^th small resource block in the j^th distributed VRB is denoted by DVRB, _j.

The scheduler determines to which PRBs it will map the distributed VRBs and the localized VRBs according to a predefined rule.

In order to map the DVRB_M to the PRB_1,, allocated for distributed VRBs, a virtual buffer is assumed. A size of the virtual buffer is equal to the total sum of sizes of PRBs to which the distributed VRBs will be mapped. That is, if one PRB is composed of M consecutive sub-carriers and a total of D PRBs to which the distributed VRBs will be mapped are allocated, a size of the virtual buffer 707 is MxD.

If a position where the DVRB_jj is mapped to the virtual buffer is denoted by x, the scheduler satisfies a relationship x = J χ l + j so that the

DVRB_jj are spaced apart at regular intervals of a maximum of J during the mapping.

In order to actually map the DVRB_j i mapped to the virtual buffer to the

PRBj _j allocated for distributed VRBs, the scheduler sequentially reads as much data as M corresponding to the PRB size from the virtual buffer, and sequentially maps the read data to the PRBs.

By defining the mapping rule in this way, the scheduler maximally mixes distributed VRBs in one PRB, thereby increasing frequency diversity gain and preventing the complexity increase which may occur when an integer ratio relationship is not satisfied between the size M of the PRB and the number K of small resource blocks in the PRB.

Referring to FIG. 7 that illustrates a preferred embodiment of the present invention to which the above-defined mapping rule is applied, the horizontal axis indicates a frequency axis, reference numeral 701 indicates distributed VRBs allocated for distributed transmission by the base station, and reference numeral 705 indicates a PRB allocated for localized transmission by the base station.

For 0^th, 4^th and 8^th PRBs, distributed VRBs are distributed separately for sub-carriers or sub-carrier units according to the present invention, and the distributed sub-carrier units are sequentially set according to order of VRBs. The distributed VRBs are sequentially mapped to the distributed sub-carriers according to a one-PRB size. FIG. 7 illustrates mapping of the distributed VRBs.

In FIG. 7, assuming that the total number of PRBs is 1=10 and the total number of distributed VRBs is J=3, the PRB and the distributed VRB are composed of k=15 and 1=15 small resource blocks, respectively. The total number of PRBs to which the distributed VRBs will be mapped is D=3. Therefore, indexes indicating the PRBs are denoted by i = 0, 1 , ••^• , 9 (= I - 1) and k=0, 1 , ••• , 14 (=k- l ), and indexes indicating the distributed VRBs are denoted by j = 0, 1 , 2 (= J - 1) and 1 = 0, 1 , ^■■• , 14 (=1-1 ). In addition, assuming that one PRB is composed of M=IS consecutive sub-carriers, a size of small blocks in the PRB is 1 (= M/k), i.e. one sub-carrier which is the minimum unit in the frequency domain.

In order to map the DVRB, _j to the PRB_1,, allocated for distributed VRBs, the present invention includes the virtual buffer 707.

A size of the virtual buffer 407 is the total sum, 45 (=MχD = 15x3), of PRBs to which distributed VRBs will be mapped. A position x where the

DVRB_1J is mapped to the virtual buffer 707 is calculated using a rule x = J χ / + / = 3 χ / + / such that the DVRB_1J are spaced apart at regular intervals of a maximum of J=3 during the mapping. Therefore, the DVRB_1J are mapped to the virtual buffer 707 as follows: DVRB_o,o => VB₀, DVRB₀,, => VB₃, , DVRB_0J4 => VB₄₂

DVRB _11O => VB i, DVRB i,, => VB₄, , DVRB_U4 => VB₄₃

DVRB_2,0 => VB₂, DVRB_2,, => VB₅, , DVRB_2J4 => VB₄₄

Thereafter, in order to actually map the DVRB₁ , mapped to the virtual buffer 707 to the PRB_1,, allocated for distributed VRBs, the scheduler sequentially reads as much data as M= 15 corresponding to the PRB size from the virtual buffer 707, and sequentially maps the read data to the PRBs.

That is, the scheduler maps data 709 of positions 0-14 in the virtual buffer 707 to the 0^th PRB, maps data 711 of positions 14-29 in the virtual buffer 707 to the 4^th PRB, and maps data 713 of positions of 30-44 in the virtual buffer 707 to the 8^th PRB.

In sum, the present invention divides each of distributed VRBs into small resource blocks, for example, sub-carrier units, maps the sub-carriers in the virtual buffer 707 at stated intervals on a mixed basis, sequentially distributes the virtual resource blocks, which were sequentially mapped to the sub-carrier on a mixed basis, according to a set size of the physical resource block, and then allocates them to the corresponding physical resource blocks. Here, as many virtual resource blocks as the number of the distributed VRBs are mapped on a scattered basis according to a size of the physical resource block.

In other words, it is assumed that each of the distributed VRBs is divided into 15 small resource blocks. For example, a 0^th VRB is divided into 0^th,

1^st, 2^nd, 3^rd, 4^th, 5^th, 6^th, 7^th, 8^th, 9^th, 10^th, 11^th, 12^lh, 13^th and 14^th small resource blocks, a 1^st VRB is divided into 15^th, 16^lh, 17^th, 18^th, 19^th, 20^th, 21^st, 22^nd, 23^rd,

24^th, 25^th, 26^th, 27^th, 28^th and 29^th small resource blocks, and a 2^nd VRB is divided into 30^lh, 31^sl, 32^nd, 33^rd, 34^th, 35^th, 36^th, 37^th, 38^th, 39^th, 40^th, 41^st, 42^nd, 43^rd and 44^th small resource blocks.

According to the present invention, for the distributed VRBs, small resource blocks of different distributed VRBs are alternately mapped to the virtual buffer at regular intervals in order of 0, 15, 30, 1 , 16, 31 , 2, 17, 32, 3, 18, 33, 4, 19, 34, 5, 20, 35, •••. That is, it can be noted that the small resource blocks in the same distributed VRB are mapped to the virtual buffer at stated intervals on a scattered basis.

In addition, the small resource blocks arranged according to the mapping rule are sequentially allocated at intervals determined according to PRB distribution depending on a size of one resource block of the PRB.

Therefore, the present invention provides diversity between the distributed VRBs, and maps the mixed small resource blocks of the diversity- guaranteed distributed VRB on the PRBs at regular intervals on a scattered basis, thereby maximally guaranteeing frequency diversity gain during data transmission.

By defining the foregoing mapping rule, the information that the terminal needs in order to detect resource mapping positions of the base station needs the total number J of distributed VRBs and the size M of the PRB, or values equivalent thereto. Therefore, as the base station signals the information on the number to the terminal, both the base station and the terminal can calculate the accurate mapping position of each distributed VRB in the PRB according to the common rule. The signaling can be physical layer signaling or upper layer signaling. The total number of PRBs can be predetermined taking the system band into account.

A description will now be made of a transmission apparatus and a reception apparatus according to the present invention. The transmission apparatus and the reception apparatus can be commonly applied to the first to fifth embodiments.

FIG. 8 is a diagram illustrating a structure of a transmission apparatus according to a preferred embodiment of the present invention.

Referring to FIG. 8, in order to transmit desired data 802 to a terminal #1, a base station performs channel coding on the data at an encoder 604. A convolutional encoder, a turbo encoder, or a Low Density Parity Check (LDPC) encoder can be used as the encoder 804. A modulator 806 performs modulation, such as Quadrature Phase Shift Keying (QPSK), 8-ary Phase Shift Keying (8PSK), 16-ary Quadrature Amplitude Modulation (16QAM) and 64-ary Quadrature Amplitude Modulation (64QAM), on the channel-coded signal. A rate matching block for performing repetition and puncturing can be added between the encoder 804 and the modulator 806.

A serial-to-parallel converter 808 takes charge of converting a serial output of the modulator 806 into a parallel signal. A radio resource mapper 810 maps an input signal to radio resources allocated by a scheduler 854.

The scheduler 854 performs radio resource allocation taking into account scheduling request information and channel status of the terminal. The scheduler 854 maps the distributed VRBs and the localized VRBs to the corresponding PRBs according to the mapping rules of the first to third embodiments, and allocates the PRBs to the terminals according to a transmission scheme of the corresponding mapped VRBs.

Therefore, the scheduler 854 performs scheduling according to Equation

(1) to Equation (5) indicating the mapping rules of the first and second embodiments such that L = {0, 4, 8} in cell #0, L = { 1 , 5, 9} in cell # 1, and L = {0, 2, 6} in cell #2. In the distributed transmission mapping rule according to the third embodiment, using Equation (6) and Equation (3), L = {0, 3, 6} in cell #0, L = { 1 , 4, 7} in cell #1, and L = {2, 5, 8} in cell #2.

Parameter information required for applying the mapping rule of distributed resource blocks for the first to third embodiments, i.e. indexes T indicating PRBs and indexes 'j' indicating distributed VRBs, are signaled to the reception apparatus.

In addition, according to the fourth and fifth embodiments, the scheduler 854 performs radio resource allocation taking into account scheduling request information and channel status of the terminal. According to the fourth and fifth embodiments of the present invention, the radio resource mapper 810 uses a method in which distributed VRBs are mapped in the PRBs allocated for VRBs. Further, the radio resource mapper 810 appropriately maps the distributed VRBs and the localized VRBs to the PRBs. That is, it can be noted that the small resource blocks in the same distributed VRB are mapped to the virtual buffer at stated intervals on a scattered basis.

In addition, the radio resource mapper 810 sequentially allocates the small resource blocks arranged according to the mapping rule, at intervals determined according to PRB distribution depending on a size of one resource block of the PRB. The radio resource mapper 810 appropriately maps the localized VRB to the remaining PRBs.

The radio resource mapper 810 signals to the reception apparatus the information necessary for applying the mapping rule of the present invention, i.e. the total number J of distributed VRBs and the size M of the PRBs, or values equivalent thereto.

A data multiplexer 812 multiplexes the data signals that the base station desires to transmit to its terminals (terminal #1 to terminal #3). For example, the data 826 that the base station desires to transmit to a terminal #k is input to the multiplexer 812 via an encoder 828, a modulator 830, a serial-to-parallel converter 832 and a radio resource mapper 810. That is, the data multiplexer 812 multiplexes the data signals being delivered to other terminals of each cell.

Control information 836 that the terminal needs in order to demodulate and decode the data signal, after passing through an encoder 838, a modulator 840 and a serial-to-parallel converter 842, is mapped by a radio resource mapper 844 to the radio resources allocated by the scheduler 854, or is mapped to predefined radio resources. Multiple channels for transmitting the control information can exist separately for the characteristics of the control information.

A pilot signal 846 for channel estimation, after passing through a modulator 848 and a serial-to-parallel converter 850, is mapped by a radio resource mapper 852 to the radio resources allocated by the scheduler 854, or mapped to predefined radio resources.

When the control information or the pilot is mapped to the predefined radio resources, the terminal can recognize information on the radio resources as system information in the call setup or reconfiguration phase between the terminal and the base station. Alternatively, the control information or the pilot can also be appropriately mapped to the distributed VRBs and localized VRBs according to the mapping rule, and when it is transmitted with the distributed transmission basis according to the present invention, a method of mapping the distributed VRBs in the PRBs allocated for distributed VRBs is equal to that in FIG. 7.

A multiplexer 814 multiplexes the data signal, the control information and the pilot signal, which are allocated to the radio resources determined according to the mapping rule. An Inverse Fast Fourier Transform (IFFT) block 816 performs IFFT calculation on the multiplexed signal. The output of the IFFT block is converted by a parallel-to-serial converter 818. A Cyclic Prefix (CP) adder 820 adds a CP to the output signal of the parallel-to-serial converter 818, and a Radio Frequency (RF) transmission block 822 RF-processes the CRC- added signal and transmits the RF-processed signal.

FIG. 9 is a diagram illustrating a structure of a reception apparatus of a terminal according to a preferred embodiment of the present invention.

Referring to FIG. 9, a CP remover 902 removes a CP from a signal received at the terminal, and a serial-to-parallel converter 904 converts an input serial signal into a parallel signal.

A Fast Fourier Transform (FFT) block 906 performs FFT calculation, and a demapper 907 extracts data allocated to the terminal, and pilot control information. A parallel-to-serial converter 908 converts the parallel signal into a serial signal and a demultiplexer 909 classifies data, pilot and control information. A channel estimator 912 extracts a pilot signal from the output of the demultiplexer 909, thereby obtaining channel estimated values.

A channel equalizer 918 performs channel compensation on the received signal using the acquired channel estimated value. The channel compensated signal undergoes demodulation and decoding through a demodulator 920 and a decoder 922 using separate control information that the terminal has received, thereby finally acquiring the data.

In the demodulation and decoding phase, the reception apparatus can appropriately extract the data that it intends to demodulate and decode, according to the same rule as the mapping rule of the distributed VRBs and localized VRBs, defined in the transmission apparatus.

That is, the demodulator calculates correct mapping positions of distributed VRBs allocated thereto on the PRBs using received information on the total number J of distributed VRBs and the size M of the PRBs in order to detect resource mapping positions of the base station, and demodulates data symbols in the corresponding mapping positions. The reception apparatus decodes the demodulated symbols, thereby acquiring transmitted data symbols.

The parameter information necessary for demodulating and decoding the transmission symbols according to the mapping rule, i.e. the total number J of distributed VRBs and the size M of the PRBs, or the number L of sub-carriers divided from distributed virtual resource blocks, which is their equivalent values, are received from the transmission apparatus through signaling, and are used by the reception apparatus for the demodulation and decoding.

The demapper 907 can extract the data that the reception apparatus desires to demodulate and decode according to the same rule as the mapping rule of the distributed VRBs and the localized VRBs, defined in the transmission apparatus. The parameter information necessary for applying the rule of the transmission apparatus is signaled from the transmission apparatus.

For example, the reception apparatus receives, through signaling, indexes 'i' indicating PRBs and indexes 'j' indicating distributed VRBs, which are parameter information necessary for applying the mapping rules for the first and third embodiments of the present invention. In other words, the reception apparatus receives, through signaling, the indexes M', the indexes 'j', and information on the mapping rule used by the transmission apparatus, i.e. information indicating whether the first embodiment is applied or the third embodiment is applied.

Therefore, the reception apparatus acquires the radio resources allocated thereto using Equation (1) to Equation (6) with use of the acquired parameters. In addition, the reception apparatus acquires data symbols by demodulating and decoding the acquired radio resources.

In the first and second embodiments, a terminal in cell #0 acquires data by demodulating and decoding data from radio resources of {0, 4, 8}, a terminal in cell # 1 acquires data by demodulating and decoding data from radio resources of { 1, 5, 9}, and a terminal in cell #2, acquires data by demodulating and decoding data from radio resources of {0, 2, 6} .

In the distributed transmission mapping rule according to the third embodiment, a terminal in cell #0 acquires data from radio resources of {0, 3, 6} using Equation (6) and Equation (3), a terminal in cell #1 acquires data from radio resources of { 1, 4, 7}, and a terminal in cell #2 acquires data from radio resources of {2, 5, 8} . In addition, as described above, the parameters transmitted from the transmission apparatus include the system band of the transmission apparatus, and the parameters that a scheduler of the transmission apparatus has determined taking into account a desired transmission traffic type, CQI feedback information from terminals in the cell, etc.

In the fourth and fifth embodiments, the reception apparatus acquires data form 0^th, 4^lh and 8^th PRBs, by demodulating and decoding data from the VRBs distributed for individual sub-carriers or in determined sub-carrier units.

While the invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the scope of the present invention is not limited to the described embodiments, and should be defined by the appended claims and equivalents thereof.

Effect of the Invention

As is apparent from the foregoing description, the present invention has the following advantages.

According to the present invention, in the OFDM-based communication system using the localized transmission scheme and the distributed transmission scheme together, the base station efficiently allocates radio resources taking into account the channel status fed back from terminals and the traffic type of the base station.

The present invention minimizes intercell interference between multiple cells of the base stations, and provides maximal frequency diversity. That is, the present invention prevents performance degradation due to the intercell interference, thereby contributing to improvement in reception performance of the terminals.

In addition, the present invention scatters sub-carriers of each of multiple distributed virtual resource blocks, and maps the sub-carriers to the physical resource blocks, thereby maximizing frequency diversity gain for the transmitted data at the corresponding terminal.

Claims

WHAT IS CLAIMED IS:

1. A method for allocating a radio resource of a transmission apparatus in an orthogonal frequency division multiple access system, the method comprising: determining a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel, and a number J of distributed virtual resource blocks (VRBs) to be used for a distributed transmission scheme; determining a parameter K indicating an interval between the distributed VRBs using the I and the J; sequentially mapping the J distributed VRBs to J first PRBs having an interval of the K, among the I PRBs; mapping localized VRBs to be used for a localized transmission scheme, to the remaining (I- J) second PRBs except for the first PRBs, among the I PRBs; and allocating the PRBs to at least one terminal according to a transmission scheme of the corresponding mapped VRBs.

2. The method of claim 1 , wherein the first PRBs have indexes that increase at intervals of the K, beginning at a PRB having a unique offset for a specific cell among the 1 PRBs.

3. The method of claim 1, wherein the first PRBs have indexes calculated using the following equation: K . L± ly -i.

L = [L₁IL₁ = (j x K + offseήmod i)

where \_x\ indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, and L, indicates an index of a PRB to which a j^lh distributed VRB is mapped.

4. The method of claim 1, wherein the first PRBs have indexes calculated using the following equation: / - 1

K =

J - I

K, = {L,._m L_um = j x K + m, L_{1 11}, < /} , m = O,1,Λ

m = offsel moά{I - K - (J - \)} where \_x\ indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, L_j indicates an index of a PRB to which a j^lh distributed VRB is mapped, and 'm' is a shifted value of the L.

5. The method of claim 1, wherein the first PRBs have indexes calculated using the following equation:

- 7

L = \L L₁ = (/ x K + offseήmod I

where indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, and L_j indicates an index of a PRB to which a j^th distributed VRB is mapped.

6. The method of claim 1 , further comprising: signaling the number I of PRBs and the number J of distributed VRBs to the at least one terminal.

7. A transmission apparatus for allocating a radio resource in an orthogonal frequency division multiple access system, the apparatus comprising: a scheduler for determining a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel, and a number J of distributed virtual resource blocks (VRBs) to be used for a distributed transmission scheme, determining a parameter K indicating an interval between the distributed VRBs using the I and the J, sequentially mapping the J distributed VRBs to J first PRBs having an interval of the K, among the I PRBs, and mapping localized VRBs to be used for a localized transmission scheme, to the remaining (I-J) second PRBs except for the first PRBs, among the I PRBs; and a mapper for allocating the PRBs to at least one terminal according to a transmission scheme of the corresponding mapped VRBs, under a control of the scheduler.

8. The transmission apparatus of claim 7, wherein the scheduler determines a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel, and a number J of distributed virtual resource blocks (VRBs) to be used for a distributed transmission scheme, taking into account an available system band of the transmission apparatus, a type of transmission data traffic, and channel status information fed back from each of multiple terminals.

9. The transmission apparatus of claim 7, wherein the scheduler performs a control operation such that the first PRBs have indexes that increase at intervals of the K, beginning at a PRB having a unique offset for a specific cell among the I PRBs.

10. The transmission apparatus of claim 7, wherein the first PRBs have indexes calculated using the following equation:

K = / - 1 I

J - i

L = \L L₁ = (j x K + offset)mod I

where \_x\ indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, and L, indicates an index of a PRB to which a j^th distributed VRB is mapped.

11. The transmission apparatus of claim 7, wherein the first PRBs have indexes calculated using the following equation: / - 1

K =

J - I

^L _m = i¹,_,,,, ^L,_,», = J x K + m, L_hlll < I}, m = 0,l,Λ m = offset mod{/ - K - (J - I)] where [xj indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, L₁- indicates an index of a PRB to which a j"¹ distributed VRB is mapped, and 'm' is a shifted value of the L.

12. The transmission apparatus of claim 7, wherein the first PRBs have indexes calculated using the following equation: /

K =

J

L = \L L₁ = (/ x K + offset)mod I

where [xj indicates a maximum integer not exceeding 'x', 'offset' is a unique

13. The transmission apparatus of claim 7, further comprising: a transmitter for signaling the number I of PRBs and the number J of distributed VRBs to be used for a distributed transmission scheme, to the at least one terminal.

14. A method for receiving an allocated radio resource of a reception apparatus in an orthogonal frequency division multiple access system, the method comprising: receiving, through signaling, a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel, and a number J of distributed virtual resource blocks (VRBs) to be used for a distributed transmission scheme; determining a parameter K indicating an interval between the distributed VRBs using the I and the J, acquiring J distributed VRBs which are sequentially mapped at intervals of the K, from first PRBs among the I PRBs, and acquiring the mapped localized VRBs to be used for a localized transmission scheme, from the remaining (I-J) second PRBs except for the first PRBs among the I PRBs; and acquiring transmission data according to a transmission scheme of the corresponding mapped VRBs of the PRBs.

15. The method of claim 14, further comprising: acquiring transmission data by demodulating and decoding the first PRBs having indexes that increase at intervals of the K, beginning at a PRB having a unique offset for a specific cell among the I PRBs.

16. The method of claim 14, wherein the first PRBs have indexes calculated using the following equation:

L = [L₁ L₁ = (/ x K + offseήmod I

where

indicates a maximum integer not exceeding 'x', 'offset' is a unique

17. The method of claim 14, wherein the first PRBs have indexes calculated using the following equation:

/ - 1

K —

J - i

K = {£,,„ L_1,,,, = j x K + m, L_{1 111} < /} , m = O,1,Λ m = offset mod {I - K - (J - X)) where \_x\ indicates a maximum integer not exceeding 'x', 'offset' is a unique

18. The method of claim 14, wherein the first PRBs have indexes calculated using the following equation: K =

J

L = [L₁ L₁ = (j x K + qffseήmod / j

where |_χj indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, and L_j indicates an index of a PRB to which a j"¹ distributed VRB is mapped.

19. The method of claim 14, further comprising: estimating channel quality information for each PRB and feeding back the estimated channel quality information to a transmission apparatus.

20. A reception apparatus for receiving an allocated radio resource in an orthogonal frequency division multiple access system, the reception apparatus comprising: a demapper for receiving, from a transmission apparatus through signaling, a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel, and a number J of distributed virtual resource blocks (VRBs) to be used for a distributed transmission scheme, determining a parameter K indicating an interval between the distributed VRBs using the I and the J, acquiring J distributed VRBs which are sequentially mapped at intervals of the K, from first PRBs among the I PRBs, and acquiring the mapped localized VRBs to be used for a localized transmission scheme, from the remaining (I-J) second PRBs except for the first PRBs among the I PRBs; a demodulator for demodulating the PRBs according to a transmission scheme of the corresponding mapped VRBs; and a decoder for decoding transmission data of the demodulated PRBs.

21. The reception apparatus of claim 20, wherein the first PRBs have indexes calculated using the following equation:

L = [L₁ L₁ = (J x K + offset) mod / where |_xj indicates a maximum integer not exceeding 'x\ 'offset' is a unique

22. The reception apparatus of claim 20, wherein the first PRBs have indexes calculated using the following equation:

U- i.

K =

= j x K _{+ m}, L_Lm < /}, m = 0.1,Λ

m = offset mod{/ - K - (J - I)] where |_xj indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, L_j indicates an index of a PRB to which a j^th distributed VRB is mapped, and 'm' is a shifted value of the L.

23. The reception apparatus of claim 20, wherein the first PRBs have indexes calculated using the following equation:

/

K —

J

L = KL L = (/ x K + offset)mod I

where |_xj indicates a maximum integer not exceeding 'x', 'offset' is a unique

24. The reception apparatus of claim 20, further comprising: a transceiver for estimating channel quality information for each PRB and feeding back the estimated channel quality information to the transmission apparatus.

25. A method for allocating a radio resource in an orthogonal frequency division multiple access system, the method comprising: determining a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel, and a number J of distributed virtual resource blocks (VRBs) to be used for a distributed transmission scheme, wherein the PRB and the VRB have K and L sub-carriers, respectively; sequentially mapping the J distributed VRBs to first PRBs having an interval of the K among the I PRBs; mapping sub-carriers of the distributed VRBs to sub-carriers of the first PRBs so that sub-carriers having an interval of the L among the sub-carriers constituting the J distributed VRBs are mapped to adjacent sub-carriers in the first PRBs; mapping localized VRBs to be used for a localized transmission scheme to the remaining (I-J) second PRBs except for the first PRBs among the I PRBs; and allocating the PRBs to at least one terminal according to a transmission scheme of the corresponding mapped VRBs.

26. The method of claim 25, further comprising: dividing the first PRB into K small resource blocks, and dividing the distributed VRB into L small resource blocks; and sequentially mapping the small resource blocks of each of the J distributed VRBs to the small resource blocks of the first PRB at regular intervals.

27. The method of claim 25, wherein the number K of small resource blocks of the PRB is equal to the number L of small resource blocks of the distributed VRB.

28. The method of claim 25, wherein the virtual block has an integer size which is equal to a product of the number J of distributed VRBs and the number L of small resource blocks of the distributed VRB.

29. The method of claim 25, wherein the sub-carriers having an interval of the L among the sub-carriers constituting the J distributed VRBs have an interval of the number J of distributed VRBs.

30. The method of claim 25, wherein the first PRBs have indexes that increase at intervals of the K, beginning at a PRB having a unique offset for a specific cell among the I PRBs.

31. The method of claim 25, wherein the first PRBs have indexes calculated using the following equation:

K — / - 1

J - i

L = \L L₁ = (/ x K + offseήmoά /]

where [xj indicates a maximum integer not exceeding 'x', 'offset' is a unique

32. The method of claim 25, wherein the first PRBs have indexes calculated using the following equation: / - 1

K =

J - I

L_n, = {L_{ι m} L_{1 1n} = j x K + m, L_{1 111} < /} , m = 0,l,Λ

m = offset mod{/ - K - (J - I)) where \_x\ indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, L, indicates an index of a PRB to which a j"¹ distributed VRB is mapped, and 'm' is a shifted value of the L.

33. The method of claim 25, wherein the first PRBs have indexes calculated using the following equation: /

K —

J

L = \L L₁ = (/ x K + offseήmoά I)

where [xj indicates a maximum integer not exceeding 'x', 'offset' is a unique value for each cell, and L_j indicates an index of a PRB to which a j^th distributed VRB is mapped.

34. The method of claim 25, further comprising: signaling the number I of PRBs and the number J of distributed VRBs to the at least one terminal.

35. An apparatus for allocating a radio resource in an orthogonal frequency division multiple access system, the apparatus comprising: a scheduler for; determining a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel and has K sub-carriers, and a number J of distributed virtual resource blocks (VRBs), each of which is to be used for a distributed transmission scheme and has L sub-carriers; sequentially mapping the J distributed VRBs to first PRBs having an interval of the K among the I PRBs, and mapping sub-carriers of the distributed VRBs to sub-carriers of the first PRBs so that sub-carriers having an interval of the L among the sub-carriers constituting the J distributed VRBs are mapped to adjacent sub-carriers in the first PRBs; and mapping localized VRBs to be used for a localized transmission scheme to the remaining (I-J) second PRBs except for the first PRBs among the I PRBs; and a mapper for allocating the PRBs to at least one terminal according to a transmission scheme of the corresponding mapped VRBs.

36. The apparatus of claim 35, wherein the scheduler; divides the first PRB into K small resource blocks, and divides the distributed VRB into L small resource blocks; and sequentially maps the small resource blocks of each of the J distributed VRBs to the small resource blocks of the first PRB at regular intervals.

37. The apparatus of claim 35, wherein the number K of small resource blocks of the PRB is equal to the number L of small resource blocks of the distributed VRB.

38. The apparatus of claim 35, wherein the virtual block has an integer size which is equal to a product of the number J of distributed VRBs and the number L of small resource blocks of the distributed VRB.

39. The apparatus of claim 35, wherein the sub-carriers having an interval of the L among the sub-carriers constituting the J distributed VRBs are spaced at intervals of the number J of distributed VRBs.

40. The apparatus of claim 35, wherein the first PRBs have indexes that increase at intervals of the K, beginning at a PRB having a unique offset for a specific cell among the 1 PRBs.

41. The apparatus of claim 35, wherein the first PRBs have indexes calculated using the following equation:

/ - 1

K -

J - i

L + of/seήmod I

where indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, and L₁ indicates an index of a PRB to which a j^th distributed VRB is mapped.

42. The apparatus of claim 35, wherein the first PRBs have indexes calculated using the following equation: / - 1

K =

J - i

m = offset mod{I - K - (J - \)} where indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, L₁ indicates an index of a PRB to which a j^th distributed VRB is mapped, and 'm' is a shifted value of the L.

43. The apparatus of claim 35, wherein the first PRBs have indexes calculated using the following equation:

K =

J

L = \L L₁ = (/ x K + offseήmod I

where |_xj indicates a maximum integer not exceeding 'x', 'offset' is a unique

44. The apparatus of claim 35, further comprising: signaling the number I of PRBs and the number J of distributed VRBs to the at least one terminal.

45. A method for receiving an allocated radio resource in an orthogonal frequency division multiple access system, the method comprising: receiving, through signaling, a number I of physical resource blocks

(PRBs), each of which is a mapping unit of a physical channel, and a number J of distributed virtual resource blocks (VRBs) to be used for a distributed transmission scheme, wherein the PRB and the VRB have K and L sub-carriers, respectively; acquiring from first PRBs the J distributed VRBs which are sequentially mapped to the first PRBs having an interval of the K among the I PRBs, wherein sub-carriers of the distributed VRBs are mapped to sub-carriers of the first PRBs so that sub-carriers having an interval of the L among the sub-carriers constituting the J distributed VRBs are mapped to adjacent sub-carriers in the first PRBs; acquiring localized VRBs mapped to be used for a localized transmission schemes from the remaining (I-J) second PRBs except for the first PRBs among the I PRBs; and acquiring transmission data according to a transmission scheme of the corresponding mapped VRBs of the PRBs.

46. The method of claim 45, further comprising: dividing the first PRB into K small resource blocks, and dividing the distributed VRB into L small resource blocks; and sequentially mapping the small resource blocks of each of the J distributed VRBs to the small resource blocks of the first PRB at regular intervals.

47. The method of claim 45, wherein the number K of small resource blocks of the PRB is equal to the number L of small resource blocks of the distributed VRB.

48. The method of claim 45, wherein the virtual block has an integer size which is equal to a product of the number J of distributed VRBs and the number L of small resource blocks of the distributed VRB.

49. The method of claim 45, wherein the sub-carriers having an interval of the L among the sub-carriers constituting the J distributed VRBs have an interval of the number J of distributed VRBs.

50. The method of claim 45, wherein the first PRBs have indexes that increase at intervals of the K, beginning at a PRB having a unique offset for a specific cell among the I PRBs.

51. The method of claim 45, wherein the first PRBs have indexes calculated using the following equation: / - 1

K =

J - I

L = \L L₁ = (/ x K + offs^' eήmod Ij

where indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, and Lj indicates an index of a PRB to which a j^th distributed VRB is mapped.

52. The method of claim 45, wherein the first PRBs have indexes calculated using the following equation:

K =

m = O,1,Λ

m = offset mod{/ - K • (J - 1)} where [_xj indicates a maximum integer not exceeding 'x', 'offset' is a unique

53. The method of claim 45, wherein the first PRBs have indexes calculated using the following equation:

L

where [xj indicates a maximum integer not exceeding 'x\ 'offset' is a unique

54. The method of claim 45, further comprising: estimating channel quality information for each PRB and feeding back the estimated channel quality information to a transmission apparatus.

55. A reception apparatus for receiving an allocated radio resource in an orthogonal frequency division multiple access system, the apparatus comprising: a demapper for; receiving, from a transmission apparatus through signaling, a number I of physical resource blocks (PRBs), each of which is a mapping unit of a physical channel, and a number J of distributed virtual resource blocks (VRBs) to be used for a distributed transmission scheme, wherein the PRB and the VRB have K and L sub-carriers, respectively; and acquiring from first PRBs the J distributed VRBs which are sequentially mapped to the first PRBs having an interval of the K among the I PRBs, wherein sub-carriers of the distributed VRBs are mapped to sub-carriers of the first PRBs so that sub-carriers having an interval of the L among the sub- carriers constituting the J distributed VRBs are mapped to adjacent sub-carriers in the first PRBs, and acquiring localized VRBs mapped to be used for a localized transmission schemes from the remaining (I- J) second PRBs except for the first PRBs among the I PRBs; a demodulator for demodulating the PRBs according to a transmission scheme of the corresponding mapped VRBs; and a decoder for decoding transmission data of the demodulated PRBs.

56. The reception apparatus of claim 55, wherein the demapper; divides the first PRB into K small resource blocks, and divides the distributed VRB into L small resource blocks; and sequentially maps the small resource blocks of each of the J distributed VRBs to the small resource blocks of the first PRB at regular intervals.

57. The reception apparatus of claim 55, wherein the number K of small resource blocks of the PRB is equal to the number L of small resource blocks of the distributed VRB.

58. The reception apparatus of claim 55, wherein the virtual block has an integer size which is equal to a product of the number J of distributed VRBs and the number L of small resource blocks of the distributed VRB.

59. The reception apparatus of claim 55, wherein the sub-carriers having an interval of the L among the sub-carriers constituting the J distributed

VRBs are spaced at intervals of the number J of distributed VRBs.

60. The reception apparatus of claim 55, wherein the first PRBs have indexes that increase at intervals of the K, beginning at a PRB having a unique offset for a specific cell among the I PRBs.

61. The reception apparatus of claim 55, wherein the first PRBs have indexes calculated using the following equation: / - 1

K =

J - I

L = \L L₁ = (/ x K + offseήmod I

where [_xj indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, and L_j indicates an index of a PRB to which a j tli distributed VRB is mapped.

62. The reception apparatus of claim 55, wherein the first PRBs have indexes calculated using the following equation: / - 1

K =

J - i

K = {£,_,„, £,_,„, = J x K + m, L_{1 111} < /} , m = O,1,Λ m = offset mod{/ - K - (J - X)) where \_x\ indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, L_j indicates an index of a PRB to which a j"¹ distributed VRB is mapped, and 'm' is a shifted value of the L.

63. The reception apparatus of claim 55, wherein the first PRBs have indexes calculated using the following equation: /

K =

J

L = \L L₁ = (/ x K + offseήmod I

where indicates a maximum integer not exceeding 'x', 'offset' is a unique

value for each cell, and L₁ indicates an index of a PRB to which a j ^■ th distributed VRB is mapped.

64. The reception apparatus of claim 55, further comprising: a transceiver for estimating channel quality information for each PRB and feeding back the estimated channel quality information to the transmission apparatus.