KR101646943B1 - Apparatus and method for determining of map reception failure in broadband wireless communication system - Google Patents

Abstract

The base station determines whether to receive a MAP in a broadband wireless communication system. The operation of a base station includes: allocating an uplink resource to a terminal; transmitting a resource allocation IE for informing the uplink resource allocation to the terminal; And determining whether or not the terminal has received the resource allocation IE by determining whether a signal is received from the terminal through the resource specified in the resource allocation IE, , It is possible to allocate resources for fixed resource allocation and synchronous retransmission with a minimum overhead and increase the efficiency of resource use.

MAP message, Log Likelihood Ratio (LLR), Signal to Interference and Noise Ratio (SINR), fixed resource allocation, synchronous retransmission

Description

[0001] APPARATUS AND METHOD FOR DETERMINING OF MAP RECEPTION FAILURE IN BROADBAND WIRELESS COMMUNICATION SYSTEM [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadband wireless communication system, and more particularly, to an apparatus and method for determining failure in map reception of a terminal in a broadband wireless communication system.

In a 4th generation (4G) communication system, which is a next generation communication system, a service having various Quality of Service (hereinafter referred to as 'QoS') is provided to users by using a transmission rate of about 100 Mbps Active research is underway. The representative communication system is IEEE (Institute of Electrical and Electronics Engineers) 802.16 system. The IEEE 802.16 system uses an Orthogonal Frequency Division Multiplexing (OFDM) / Orthogonal Frequency Division Multiplexing (OFDM) scheme to support a broadband transmission network in a physical channel. (Hereinafter referred to as " OFDMA ") scheme.

In a broadband wireless communication system such as the IEEE 802.16 system, a base station allocates resources to respective terminals for transmission and reception of packets. Then, the BS transmits a resource allocation IE message indicating a resource allocation result such as the location and size of the allocated resource, the modulation scheme, the coding rate, etc. to the MS through the downlink channel. Generally, a message indicating a resource allocation result for uplink communication and a message indicating a resource allocation result for downlink communication are separately configured. A unit of information required for one resource allocation is a resource allocation IE (Information Element) do.

Resource allocation is performed on resources within a certain interval. At this time, since the resources for general data packets are allocated for every predetermined interval, the resource allocation IE for them is transmitted every predetermined interval. However, in the case of a Voice over Internet Protocol (VoIP) service in which packets are periodically transmitted, transmitting a resource allocation IE every time a packet is transmitted causes unnecessary resource waste. Accordingly, in the case of a packet having a periodic transmission period such as a VoIP packet, a fixed allocation scheme has been applied in which resources are fixedly allocated, thereby reducing resource waste due to resource allocation IEs. According to the fixed allocation scheme, in a downlink communication, a resource allocation IE and a packet are transmitted only when an initial resource is allocated, and thereafter, only a packet is transmitted without a resource allocation IE. Therefore, the UE using the fixed allocated resource continues to use the fixed allocated resource until the allocation cancel information or the allocation change information is received without the resource allocation IE. In the fixed allocation scheme, when there is a change in the previously allocated information, a resource allocation IE is transmitted for a new fixed allocation. In the case of fixed allocation resources, when allocation release information of VoIP packets is received, termination of fixed allocation resources occurs.

There is a synchronous HARQ scheme having a resource operation form similar to the fixed allocation. The synchronous HARQ scheme is a scheme for directly using resources allocated for initial transmission at the time of retransmission of a packet, and the resource allocation IE for retransmission is not transmitted. However, not transmitting the resource allocation IE for the retransmission is not enforced, and if it is desired to change the location of the resource for retransmission, the resource allocation IE for retransmission can be transmitted. The MS receiving the resource allocation IE for retransmission retransmits the packet as specified in the resource allocation IE and retransmits the packet at the location until receiving the new retransmission resource allocation IE.

When using the fixed resource allocation or the synchronous HARQ scheme in the uplink, if the UE receives a new resource allocation IE, the UE performs fixed resource allocation or synchronous retransmission using allocation information of a new resource allocation IE. That is, the resource allocation IE for the fixed resource allocation or the synchronous HARQ scheme is valid for a plurality of frames during one transmission only. Therefore, if the resource allocation IE is not received, resource allocation that is not recognized by the UE is continuously performed during a period of the multiple frames, thereby wasting resources. Therefore, the BS must prevent resources from being wasted by retransmitting the resource allocation IE or retrieving resources according to whether the UE has received the uplink resource allocation IE. Therefore, a technique for determining whether or not the base station has received the uplink resource allocation IE should be proposed.

Accordingly, it is an object of the present invention to provide an apparatus and a method for preventing waste of resources in a broadband wireless communication system.

It is another object of the present invention to provide an apparatus and method for determining whether a terminal has received resource allocation information in a broadband wireless communication system.

It is still another object of the present invention to provide an apparatus and method for determining whether to receive resource allocation information using a signal received through a resource allocated to a terminal in a broadband wireless communication system.

It is another object of the present invention to provide an apparatus and method for determining whether to receive resource allocation information using a LLR (Log Likelihood Ratio) measured in a resource allocated to a terminal in a broadband wireless communication system.

It is another object of the present invention to provide an apparatus and method for determining whether or not to receive resource allocation information using a signal quality measured in a resource allocated to a terminal in a broadband wireless communication system.

According to an aspect of the present invention, there is provided a method of operating a base station in a broadband wireless communication system, including: allocating an uplink resource to a terminal; allocating a resource allocation IE And determining whether the UE has received the resource allocation IE by determining whether a signal is received from the UE through the resource specified in the resource allocation IE .

According to a second aspect of the present invention, in a broadband wireless communication system, a base station apparatus includes a scheduler for allocating an uplink resource to a terminal, a resource allocation IE for informing the uplink resource allocation to the terminal, And a determination unit for determining whether or not the terminal has received the resource allocation IE by determining whether a signal is received from the terminal through the resource specified in the resource allocation IE.

In a broadband wireless communication system, it is provided to a base station whether a terminal correctly received a MAP, so that resources for fixed resource allocation and synchronous retransmission are allocated only with a minimum overhead, .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Hereinafter, the present invention will be described with reference to a technique for determining whether or not a terminal has received resource allocation information. Hereinafter, the present invention will be described by taking an example of a wireless communication system of Orthogonal Frequency Division Multiplexing (OFDM) / Orthogonal Frequency Division Multiple Access (OFDMA) , And can be similarly applied to other types of wireless communication systems. Although the fixed allocation scheme and the synchronous retransmission have been described in order to explain the necessity of the present invention, the present invention can be similarly applied to the fixed allocation scheme and the general resource allocation scheme as well as the synchronous retransmission.

Hereinafter, the term " SINR (Signal to Interference and Noise Ratio) " is used to express the same technical idea of channel quality. The term " Signal to Noise Ratio (SNR) ). ≪ / RTI > Hereinafter, terms such as a map and a resource allocation IE (Information Element) are mixed, but they are all for expressing the same technical idea called control signaling including resource allocation information.

The frame structure of the broadband wireless communication system according to the present invention is shown in FIG.

As shown in FIG. 1, a plurality of frames 120 constitute one super frame 110. Each frame 120 is composed of a plurality of subframes 130, and each subframe 130 is composed of a plurality of OFDMA symbols. Resource allocation is performed on resources in each subframe 130, and resources in each subframe 130 are allocated on a resource block (RB) basis. The resource block is also called an LRU (Logical Resource Unit). That is, a terminal performing communication with a base station is allocated an integer number of resource blocks.

Accordingly, the MAP message is transmitted for each subframe 130. At this time, each resource allocation IE (Information Element) indicating each resource allocation result included in the MAP message uses a unique sequence allocated to the UE to receive the resource allocation IE, and performs cyclic redundancy check (CRC) and scrambling scrambling, and so on. For example, a MACID (Media Access Control IDentifier) may be used as the unique sequence. In other words, a method of masking the CRC with the MAC ID or a method of scrambling the resource allocation IE and the CRC with the MAC ID after adding the CRC to the resource allocation IE is used. Accordingly, each mobile station identifies a resource allocation IE for itself by performing CRC check and descrambling on each of the resource allocation IEs with a unique sequence assigned thereto. This resource allocation IE encoding scheme is referred to as separate coding, and the resource allocation IE decoding scheme corresponding to the resource allocation IE coding scheme is referred to as blind decoding.

The fixed resource allocation scheme is generally applied to the traffic in which packets are generated periodically. When assigning a fixed resource, an allocation period of a fixedly allocated packet is determined using a fixed resource allocation period (Allocation Period). At this time, the fixed resource allocation period is represented by the number of frames. According to the fixed resource allocation period, the packet is periodically transmitted through a fixed location resource. When there is no allocated allocation information for the previous packet transmission time, packet transmission is performed without a fixed resource allocation IE.

The synchronous retransmission scheme applies the resource allocation information applied to the initial transmission to the retransmission in the same manner. Therefore, a resource allocation IE for retransmission in a synchronous retransmission is not required. The synchronous retransmission is performed according to the location of the subframe to which the resource is allocated, and the synchronous retransmission is performed using the resource allocation information applied to the initial transmission at the preset retransmission time.

When a fixed resource allocation is applied for uplink communication, the BS transmits an uplink fixed resource allocation IE to the UE. The UE receives the fixed resource allocation IE and transmits an uplink packet using fixed resources according to resource allocation information provided through the fixed resource allocation IE. If the UE fails to receive the uplink fixed resource allocation IE, the UE can not use the fixed resource because it does not know the allocation of the fixed resource. However, the BS determines that the UE has received the fixed resource allocation IE, and thus attempts to receive the uplink packet through the fixed resource. However, since the UE does not transmit a packet through the fixed resource, the Node B fails to receive a packet, and the Node B determines that decoding has failed and transmits a NACK (Non-ACKnowledge). That is, the UE does not transmit a packet, and the BS repeatedly generates an unreasonable phenomenon of transmitting a NACK. To solve this problem, there is a need for a method for the base station to determine whether the terminal has received the fixed resource allocation IE. Even if the first fixed resource allocation IE is received, the same problem occurs even if the fixed resource allocation IE for changing the fixed resource is not received.

When a synchronous retransmission scheme is applied for uplink communication, the UE performs retransmission using resource allocation information applied to the initial transmission of the packet. At this time, if a new synchronous retransmission resource allocation IE for changing resources for retransmission is received, the terminal performs synchronous retransmission through the resource specified in the new synchronous retransmission resource allocation IE. If the UE fails to receive the new synchronous retransmission resource allocation IE, the UE retransmits the packet at the location of the resource for initial transmission, and the BS retransmits the retransmission packet at the resource specified in the new synchronous retransmission resource allocation IE. As shown in FIG. That is, since the position of the resource recognized by the terminal and the base station is different, the attempt of receiving the retransmission packet of the base station fails, and the base station determines that decoding has failed and transmits a NACK. That is, the UE performs retransmission through resources at the initial transmission, and the BS repeatedly generates an unreasonable phenomenon of transmitting a NACK. To solve this problem, there is a need for a method for the base station to determine whether the terminal has received a synchronous retransmission resource IE.

In order to inform the base station of whether the uplink map is received, a scheme of using HFA (HARQ feedback allocation) for the MAP has been proposed. If the map is successfully received, ACK (acknowledge) is transmitted from the HFA for the map. If the map is not received, no confirmation signal is transmitted because the HFA for the map can not be grasped. The base station receives a signal from the HFA for the map, and when ACK is received, it determines that the terminal has successfully received the map. If no signal is received, it determines that the terminal has not received the map. According to the determination of the reception failure, the base station retransmits the map. Using the HFA would be a simple solution. However, by using the HFA for the map, the amount of control information to be transmitted by the terminal increases, and power for transmitting other packets due to power consumption by transmission of control information is reduced, There is a problem.

Accordingly, the present invention proposes a technique for providing information on whether or not a terminal receives a map to a base station without signaling in order to improve the performance of the system. When transmitting a fixed resource allocation IE or a synchronous retransmission resource allocation IE for the uplink, the resource allocation IEs allocate a new fixed resource, or. It indicates the change of the resource allocation used in the fixed resource allocation or the synchronous retransmission. That is, a new fixed resource allocation IE or a new synchronous retransmission resource allocation IE causes fixed resource allocation and synchronous retransmission to be performed in a new location resource. At this time, the base station receives the fixed allocation packet or the synchronous retransmission packet at the changed new location. If the MS successfully receives a newly transmitted resource allocation IE, the BS can receive a fixed allocation packet or a synchronous retransmission packet at a changed location. On the other hand, if the UE does not receive the newly transmitted resource allocation IE, the BS does not receive the packet at the changed location.

If the UE does not transmit a packet through the resource at the location specified in the resource allocation IE, no signal will be received from the LRU (Logical Resource Unit) specified in the resource allocation IE. Accordingly, the BS can determine whether the MS has received the MAP by determining whether a transmission signal of the MS has been received in the LRU specified in the resource allocation IE. Whether or not a transmission signal of the terminal has been received can be determined through the following process.

After transmitting the new resource allocation IE, the BS determines, based on the Modulation and Coding Scheme (MCS) level specified in the new resource allocation IE and the number of LRUs Calculates a log likelihood ratio (LLR) value for each bit with respect to the signal extracted from the bitstream, and transmits the bitstream to a convolutional turbo code (CTC) decoder.

Here, the LLR is a value indicating the probability that the value of each bit is 1 or 0 based on the received value of the signal, and indicates whether the value of 1 or 0 is received correctly on a bit-by-bit basis. The LLR is determined on a symbol-by-symbol basis using the SINR value measured using the pilot of the received signal and the symbol value of the received signal. The specific procedure of calculating the LLR may vary depending on the silver modulation scheme and the reception algorithm of the receiver. For example, when a minimum mean square error (MMSE) reception technique is used and QPSK modulation is applied, the LLR value is determined according to Equation (1) and Equation (2).

_{LLR 1 = SINR * (- (} Signal_Real + 1 / √2) 2 + (Signal_Real - 1 / √2) 2)

In Equation (1), LLR ₁ is the LLR of the first bit of the QPSK symbol, SINR is the SINR value measured using the pilot of the received signal when the modulation scheme is QPSK, and Signal_Real is the real value of the received signal it means.

_{LLR 2 = SINR * (- (} Signal_ Imag + 1 / √2) 2 + (Signal_Imag - 1 / √2) 2)

In Equation (2), LLR ₁ is the LLR of the first bit of the QPSK symbol, SINR is the SINR value measured using the pilot of the received signal when the modulation scheme is QPSK, and Signal_Imag is the imaginary value of the received signal it means.

However, in addition to the method shown in Equation (1) and Equation (2), any method known or obvious to a person skilled in the art can be used for the LLR calculation.

The CTC decoder determines the value of each bit as 0 or 1 by using the LLR value calculated for each bit. The higher the SINR (Signal to Noise Ratio) of the received signal is, the higher the intensity of the received signal is, so the LLR values also become larger. For the same SINR, the lower the MCS level, the higher the LLR value is obtained.

The LLR value is a large value having a positive sign (+) when a signal close to 1 is received when the signal is transmitted, and a negative sign (-) when a value close to -1 is received when the signal is transmitted. ). ≪ / RTI > That is, when the absolute value of the LLR value of the received signal is taken, the larger the absolute value, the higher the SINR of the received signal. Therefore, the average LLR of the transmitted signal can be used to determine whether to receive the map. Here, the 'average LLR' means an average value of absolute values of LLR values for all the symbols of the received signal.

When using SFBC (Space Frequency Block Coding) as a multiple input multiple output (MIMO) mode, an average value of absolute values of LLR values of bits transmitted according to a modulation order is input to channel models Ped-B and Veh- The results are shown in Table 1 below.

SINR
f (MIMO = SFBC, Modulation, SINR, Channel) QPSK 16QAM 64QAM Ped-B Veh-A Ped-B Veh-A Ped-B Veh-A -20 0.940189 0.937645 0.500576 0.499489 0.33267 0.331561 -19 0.933435 0.943287 0.496404 0.502129 0.330286 0.334011 -18 0.957986 0.962314 0.50926 0.512537 0.339499 0.340485 -17 0.967573 0.975831 0.516626 0.519238 0.342542 0.345067 -16 0.991867 0.981987 0.530161 0.523982 0.350715 0.347454 -15 1.014847 1.011203 0.541271 0.539077 0.359263 0.357864 -14 1.048882 1.058697 0.557219 0.564768 0.370222 0.373574 -13 1.084163 1.100698 0.57616 0.585932 0.381402 0.386865 -12 1.161728 1.153463 0.615037 0.613143 0.40831 0.405332 -11 1.245166 1.238299 0.655422 0.656196 0.433877 0.432527 -10 1.24437 1.299341 0.659885 0.688717 0.434708 0.45259 -9 1.387769 1.424592 0.723439 0.747454 0.480969 0.491848 -8 1.519072 1.536785 0.795161 0.799989 0.520001 0.52462 -7 1.663263 1.711211 0.859477 0.884768 0.56342 0.576712 -6 2.018341 2.062765 1.016612 1.045673 0.662567 0.674408 -5 2.045739 2.300971 1.04293 1.147474 0.669463 0.738368 -4 2.469065 2.663666 1.215509 1.289091 0.778302 0.827139 -3 3.064493 3.050359 1.444824 1.456736 0.926449 0.924111 -2 3.691462 3.805578 1.699269 1.724612 1.070569 1.090509 -One 4.09404 4.601399 1.850055 2.020682 1.160154 1.264639 0 5.560318 5.790615 2.419189 2.424429 1.475228 1.507776

When SM (Spatial Multiplexing) is used as the MIMO mode, the average value of the absolute values of the LLR values according to the modulation order for rank 1 is measured in the channel models Ped-B and Veh-A environment, >.

SINR
f (MIMO = SM, Modulation, SINR, Channel) QPSK 16QAM 64QAM Ped-B Veh-A Ped-B Veh-A Ped-B Veh-A -20 0.908927 0.907996 0.483258 0.480235 0.321379 0.319514 -19 0.902769 0.91295 0.477992 0.482849 0.318508 0.321807 -18 0.933947 0.928824 0.49425 0.492503 0.329849 0.328334 -17 0.94174 0.952705 0.493788 0.501563 0.329801 0.335392 -16 0.967557 0.963237 0.507942 0.503135 0.339187 0.336192 -15 0.982762 0.992921 0.517333 0.520569 0.345864 0.348721 -14 1.022418 1.024149 0.539023 0.537954 0.361146 0.360562 -13 1.055518 1.070835 0.546723 0.559229 0.367682 0.374911 -12 1.139907 1.106067 0.596073 0.575447 0.400604 0.38777 -11 1.215366 1.209281 0.609139 0.626408 0.413866 0.421934 -10 1.213518 1.24491 0.608431 0.641055 0.410306 0.430788 -9 1.40507 1.408988 0.695738 0.716823 0.472893 0.4849 -8 1.503284 1.497166 0.758954 0.742999 0.511505 0.506302 -7 1.70543 1.679676 0.883227 0.828648 0.587535 0.560575 -6 1.959371 2.037413 1.019322 0.990494 0.670783 0.665782 -5 1.855906 2.285663 0.888356 1.073293 0.59239 0.719501 -4 2.450876 2.662796 1.10027 1.191205 0.751503 0.80953 -3 3.129134 3.033705 1.380193 1.364346 0.929269 0.907395 -2 3.693524 3.760273 1.599803 1.573996 1.067412 1.066057 -One 4.273632 4.738796 1.719361 1.893329 1.147055 1.250774 0 5.417856 6.279166 2.246587 2.400892 1.437108 1.556727

Table 1 and Table 2 show the results of measuring the average LLR by changing the setting of the MIMO mode, the modulation method, and the SINR under the environment of the channel models Ped-B and Veh-A. The results of Table 1 and Table 2 may vary depending on the specific MIMO mode, modulation scheme, SINR range, and the like. Therefore, it is preferable that the tables as shown in Table 1 and Table 2 are determined using the measurement result in the communication environment according to the characteristics of the system to which the present invention is applied.

When the UE does not transmit a packet, since no signal is received in the allocated LRU, the SINR value measured in the LRU will be very low. This is because the terminal does not transmit a packet and thus the strength of the signal does not exist and only noise exists. In this case, the SINR will be a very low value of -10 dB or less. Referring to Table 1 and Table 2, the average LLR value in each SINR for the QPSK (Quadrature Phase Shift Keying), 16QAM (16-Quadrature Amplitude Modulation), and 64QAM modulation schemes decreases as the SINR decreases Lt; / RTI > Therefore, if the LLR value measured at the location of the resource specified in the fixed resource allocation IE for the uplink or the synchronous retransmission resource allocation IE has a very small value as shown in Table 1 or Table 2, It can be known that the SINR in the corresponding LRU is very low, and based on this, it can be estimated that the terminal has not received the map.

The indoor communication environment and the outdoor outdoor channel environment are different and the communication environment of a city where a lot of buildings are located and the communication environment of a rare country where a building is rare are different. Therefore, the SINRs of the terminals measured according to the respective communication environments are all different. Since the actual communication environment is difficult for the base station to know, it is preferable to use the minimum LLR value among the average LLR values measured in various channel models to determine whether the terminal receives the map. In other words, since it is difficult to judge whether or not the actual communication environment is communicated in a situation where a pedestrian or moving means is in communication, the minimum value of the average LLR values of a plurality of channel models should be used as an average LLR . Accordingly, it is preferable that the minimum LLR value used for determining whether or not the terminal receives the map is the smallest among the LLR values for each channel model shown in Table 1 and Table 2, The LLR values are summarized in Table 3 and Table 4 below.

SINR
f (MIMO = SFBC, Modulation, SINR, Channel) QPSK 16QAM 64QAM MIN_LLR MIN_LLR MIN_LLR -20 0.937645 0.499489 0.331561 -19 0.933435 0.496404 0.330286 -18 0.957986 0.50926 0.339499 -17 0.967573 0.516626 0.342542 -16 0.981987 0.523982 0.347454 -15 1.011203 0.539077 0.357864 -14 1.048882 0.557219 0.370222 -13 1.084163 0.57616 0.381402 -12 1.153463 0.613143 0.405332 -11 1.238299 0.655422 0.432527 -10 1.24437 0.659885 0.434708 -9 1.387769 0.723439 0.480969 -8 1.519072 0.795161 0.520001 -7 1.663263 0.859477 0.56342 -6 2.018341 1.016612 0.662567 -5 2.045739 1.04293 0.669463 -4 2.469065 1.215509 0.778302 -3 3.050359 1.444824 0.924111 -2 3.691462 1.699269 1.070569 -One 4.09404 1.850055 1.160154 0 5.560318 2.419189 1.475228

SINR
f (MIMO = SM, Modulation, SINR, Channel) QPSK 16QAM 64QAM MIN_LLR MIN_LLR MIN_LLR -20 0.907996 0.480235 0.319514 -19 0.902769 0.477992 0.318508 -18 0.928824 0.492503 0.328334 -17 0.94174 0.493788 0.329801 -16 0.963237 0.503135 0.336192 -15 0.982762 0.517333 0.345864 -14 1.022418 0.537954 0.360562 -13 1.055518 0.546723 0.367682 -12 1.106067 0.575447 0.38777 -11 1.209281 0.609139 0.413866 -10 1.213518 0.608431 0.410306 -9 1.40507 0.695738 0.472893 -8 1.497166 0.742999 0.506302 -7 1.679676 0.828648 0.560575 -6 1.959371 0.990494 0.665782 -5 1.855906 0.888356 0.59239 -4 2.450876 1.10027 0.751503 -3 3.033705 1.364346 0.907395 -2 3.693524 1.573996 1.066057 -One 4.273632 1.719361 1.147055 0 5.417856 2.246587 1.437108

In order to determine whether or not to receive the MAP of the MS, the BS calculates a measured average LLR value obtained by averaging absolute values of LLR values in an LRU allocated to the MS, and determines a MIMO mode and a modulation scheme Lt; / RTI > corresponding to the minimum LLR value. If the measured average LLR is greater than or equal to the minimum LLR, the BS determines that the MS has successfully received a new resource allocation IE. If the measured average LLR is less than the minimum LLR, It is determined that the reception of the new resource allocation IE has failed.

The minimum LLR value used to determine whether to receive the map is selected according to the MIMO mode and the modulation scheme. Since the SINR value in the LRU to which the signal is not transmitted can not be known, the minimum LLR value corresponding to the SINR in Table 1 and Table 2 depends on the performance of the MAP . Therefore, a proper SINR determination method should be used. For example, as shown in Equation (3), the BS may set a minimum LLR value corresponding to a predetermined target SINR (Target_SINR) to a reference minimum LLR (Reference_Minimum_LLR) value As shown in FIG.

Reference_Minimum_LLR = f (MIMO mode, Modulation, Target_SINR)

In Equation (3), the Reference_Minimum_LLR is a reference LLR value for determining whether a MAP is received, f () is a function for determining the Reference_Minimum_LLR, the MIMO mode, the Modulation and the Target_SINR are MIMO modes applied to the UE, And the input parameters of f () as a predefined target SINR.

In another example, the BS estimates a minimum SINR value using the SINR value of the MS, and may determine the minimum LLR value corresponding to the minimum SINR as the reference minimum LLR value. Generally, for uplink resource allocation, the BS calculates an initial SINR (Initial_SINR) value of a terminal using a CQI feedback signal (Channel Quality Indicator Feedback) of the terminal. According to another embodiment of the present invention, the BS can calculate an initial SINR value of the MS using a sounding signal of the MS. The base station determines the MIMO mode and modulation scheme of the UE using the initial SINR value, and generates and transmits a resource allocation IE for the uplink. The terminal transmits a packet according to the resource allocation information included in the resource allocation IE received from the base station. If there is an error in the calculation of the SINR, the base station receives a low power signal and transmits a NACK to the mobile station through a cyclic redundancy check (CRC) procedure. Upon receiving the NACK, the UE retransmits the packet, and the BS combines the retransmission packet with the initial packet. At this time, the SINR for the packet increases because the retransmission packet is combined every time the retransmission is received. The increase of the SINR due to the combination of the retransmission packets is determined according to the retransmission scheme, the MIMO mode, and the like. Here, the retransmission scheme includes a CC (Chase Combining) scheme for sending the same packet as the initial packet upon retransmission, and an IR (Incremental Redundancy) scheme for sending a subpacket of the initial packet upon retransmission. In general, the system allows only retransmissions as many as the maximum number of retransmissions (N_Max_ReTx) to prevent infinite retransmission. Thus, if a particular terminal is serviceable in a cell, it can be seen that the SINR of the packet reaches the minimum SINR through retransmission of the maximum number of retransmissions, even in the worst case. Based on this, the minimum SINR of the UE can be calculated as Equation (4) below.

Minimum_Received_SINR = Initial_SINR - (N_Max_ReTx * ReTx_SINR_Delta)

In Equation (4), the Minimum_Received_SINR is a minimum SINR measured when a UE transmits a signal, the Initial_SINR is a SINR of a UE determined through CQI feedback, the N_Max_ReTx is a maximum retransmission count, the ReTx_SINR_Delta is a SINR Increase.

The minimum LLR value corresponding to the minimum SINR of the UE can be determined as shown in Equation (5) using Table 1 and Table 2 below.

Reference_Minimum_LLR = f (MIMO mode, Modulation, Minimum_Received_SINR)

In Equation (5), the Reference_Minimum_LLR is a reference LLR value for determining whether a MAP is received, f () is a function for determining the Reference_Minimum_LLR, the MIMO mode, the Modulation and the Minimum_Received_SINR are MIMO modes applied to the UE, And the minimum reception SINR of the terminal means the input parameters of f ().

The base station determines whether or not the terminal receives the map using the above-described parameters as follows. If Equation (6) is satisfied, the BS determines that the UE has not received the resource allocation IE.

Measured_Average_LLR <Reference_Minimum_LLR

In Equation (6), the Measured_Average_LLR denotes an average value of absolute values of LLR values in the allocated LRU, and the Reference_minimum_LLR denotes a reference LLR value for determining whether a map is received.

If Equation (7) is satisfied, the BS determines that the UE has received the resource allocation IE.

Measured_Average_LLR ≥ Reference_Minimum_LLR

In Equation (7), the Measured_Average_LLR denotes an average value of absolute values of LLR values in the allocated LRU, and the Reference_minimum_LLR denotes a reference LLR value for determining whether a map is received.

As described above, according to an embodiment of the present invention, the BS can determine whether the MS receives a MAP using the LLR value. According to another embodiment of the present invention, the base station can determine whether or not the terminal receives a map using the SINR for the received signal. That is, the BS measures an SINR with respect to a signal received through a resource allocated to the MS, on the assumption that the MS transmits a signal. Specifically, the BS calculates the average SINR of the received signal by measuring the SINR of all tones and averaging the per-tone SINR (SINR) per tone.

However, since the average SINR is an average value for all the tones, a phenomenon occurs in which the influence of the tone having the SINR lower than the average is not well reflected. Thus, a Received Bit Mutual Information Rate (RBIR) mapping can be utilized to reflect the effect of the tone with the low SINR. Generally, information on the correspondence between the SINR and the RBIR is stored in the form of a table in the base station. Therefore, the BS measures the per-tone SINR and then obtains an RBIR value corresponding to the corresponding SINR using the value of the SINR to RBIR mapping table (SINR to RBIR mapping table). For example, the mapping table is shown in Table 5 below.

QPSK 16QAM 64QAM SINR range (span)
[dB] [-20: 0.5: 27] [-20: 0.5: 27] [-20: 0.5: 27]
















RBIR value [0.0072 0.0080 0.0090
0.0101 0.0114 0.0127
0.0143 0.0159 0.0179
0.0200 0.0225 0.0251
0.0282 0.0315 0.0352
0.0394 0.0442 0.0493
0.0551 0.0616 0.0688
0.0767 0.0855 0.0953
0.1061 0.1180 0.1311
0.1456 0.1615 0.1788
0.1978 0.2184 0.2407
0.2650 0.2910 0.3190
0.3489 0.3806 0.4141
0.4493 0.4859 0.5239
0.5628 0.6024 0.6422
0.6817 0.7207 0.7584
0.7944 0.8281 0.8592
0.8872 0.9119 0.9331
0.9507 0.9649 0.9760
0.9842 0.9901 0.9942
0.9968 0.9983 0.9992
0.9997 0.9999 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000] [0.0036 0.0040 0.0045
0.0050 0.0057 0.0063
0.0071 0.0080 0.0089
0.0100 0.0112 0.0126
0.0141 0.0158 0.0176
0.0197 0.0221 0.0247
0.0276 0.0308 0.0344
0.0384 0.0428 0.0476
0.0531 0.0590 0.0656
0.0728 0.0808 0.0895
0.0990 0.1094 0.1206
0.1329 0.1461 0.1603
0.1756 0.1920 0.2094
0.2279 0.2474 0.2680
0.2896 0.3122 0.3357
0.3600 0.3852 0.4112
0.4379 0.4653 0.4933
0.5219 0.5509 0.5804
0.6103 0.6403 0.6709
0.7014 0.7317 0.7617
0.7910 0.8193 0.8463
0.8716 0.8949 0.9158
0.9343 0.9501 0.9633
0.9739 0.9821 0.9883
0.9927 0.9957 0.9976
0.9988 0.9994 0.9997
0.9999 1.0000 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000 1.0000
1.0000 1.0000] [0.0024 0.0027 0.0030
0.0034 0.0038 0.0043
0.0047 0.0054 0.0060
0.0067 0.0075 0.0084
0.0094 0.0106 0.0117
0.0132 0.0147 0.0165
0.0184 0.0207 0.0229
0.0257 0.0285 0.0319
0.0354 0.0396 0.0437
0.0488 0.0539 0.0599
0.0660 0.0732 0.0805
0.0890 0.0974 0.1073
0.1172 0.1285 0.1398
0.1525 0.1653 0.1795
0.1937 0.2092 0.2247
0.2415 0.2583 0.2763
0.2942 0.3132 0.3321
0.3519 0.3718 0.3924
0.4131 0.4345 0.4558
0.4778 0.4997 0.5223
0.5448 0.5677 0.5907
0.6141 0.6374 0.6611
0.6848 0.7087 0.7325
0.7564 0.7802 0.8036
0.8269 0.8489 0.8708
0.8904 0.9100 0.9262
0.9425 0.9547 0.9668
0.9732 0.9796 0.9840
0.9883 0.9910 0.9937
0.9954 0.9971 0.9983
0.9995 0.9998 1.0000
1.0000 1.0000]

The average RBIR of the transmitted signal is then determined by averaging the RBIR values of each tone. Then, the BS retransmits the SINR corresponding to the average RBIR in the mapping table, and the searched SINR becomes the final SINR for the received signal. The SINR value determined through the RBIR mapping is a more accurate SINR value because the effect of the tone having a low SINR is reflected as a log value.

After determining the SINR, if the following Equation (8) is satisfied, the BS determines that the UE has not received the resource allocation IE.

Measured_SINR <Minimum_Received_SINR

In Equation (8), the Measured_SINR denotes the SINR measured in the allocated resource, and the Minimum_Received_SINR denotes the minimum SINR measured when the UE transmits a signal.

When Equation (9) is satisfied, the BS determines that the UE has received the resource allocation IE.

Measured_SINR ≥ Minimum_Received_SINR

In Equation (9), the Measured_SINR denotes the SINR measured in the allocated resource, and the Minimum_Received_SINR denotes the minimum SINR measured when the terminal transmits a signal.

FIG. 2 illustrates a procedure for determining whether a base station receives a map to a terminal in a broadband wireless communication system according to the first embodiment of the present invention.

Referring to FIG. 2, in step 201, the BS determines an initial SINR of a mobile station using a CQI signal received from a mobile station. The initial SINR is information used for uplink scheduling for the UE. The CQI signal is a signal for the UE to report the channel quality, and the UE must transmit the CQI signal as long as it is connected to the base station. Here, the CQI signal includes one of sequences having orthogonality or quasi orthogonality. Therefore, the BS detects a sequence included in the CQI signal through a correlation operation, and determines a SINR value indicated by the detected sequence as an initial SINR of the UE. Generally, since the CQI signal reports a downlink channel quality, or a system using TDD (Time Division Duplex) uses the same frequency band for an uplink channel and a downlink channel, The SINR of the UE can be determined using the CQI for the UE.

In step 203, the BS determines a MIMO mode and a modulation scheme of the MS on the basis of the initial SINR, allocates resources, and transmits an MIMO mode, a modulation scheme, and an uplink resource And transmits the allocation IE to the terminal. In this case, the resource allocation IE may be a fixed resource allocation IE for allocating or changing fixed resources, a synchronous retransmission resource allocation IE for changing a retransmission resource in a synchronous retransmission scheme, a random resource allocation IE, or the like.

After transmitting the uplink resource allocation IE, the BS proceeds to step 205 and attempts to receive the signal of the UE at the resource allocated by the uplink resource allocation IE. In other words, the base station extracts signals mapped to the sub-carriers included in the allocated resource, performs demodulation and channel decoding, and then performs a CRC check.

Then, the BS proceeds to step 207 and checks the result of the CRC check. That is, the BS determines whether the CRC check is successful or unsuccessful. If the CRC check is successful, the BS proceeds to step 209, receives a signal from the MS, determines that data decoding is successful, and transmits an ACK to the MS. On the other hand, if the CRC check fails, the BS performs steps 211 to 217 to determine whether the UE has not transmitted a signal or has transmitted a signal but has failed in decoding.

That is, if the CRC check fails, the BS proceeds to step 211 and determines a measured average LLR for a signal received from the allocated resource. Here, the measured average LLR means an average value of absolute values of LLR values per bit of all tones calculated under the assumption that the terminal transmits a signal. That is, the BS calculates the LLR values for each bit according to the modulation scheme of the MS, and calculates an average value of the LLR values.

After determining the measured average LLR, the BS proceeds to step 213 and determines a minimum received SINR. Herein, the minimum SINR means a minimum SINR measured when a mobile station transmits a signal. For example, the minimum SINR may be determined using the initial SINR, the maximum number of retransmissions, and the SINR increase per retransmission, determined in step 201. [ For example, the BS determines the minimum SINR by subtracting a product of the maximum retransmission number and the SINR increase value from the initial SINR, as shown in Equation (4).

After determining the minimum SINR, the BS proceeds to step 215 and determines a reference minimum LLR. The reference minimum LLR is a reference LLR value for determining whether or not a map is received, and is a minimum value of an LLR for a signal received in the channel environment of the minimum reception SINR, and is searched in a predefined table. The table takes the MIMO mode, the modulation scheme and the minimum received SINR as look-up parameters, and includes the LLR values determined by pre-simulation. The simulations are conducted under conditions of various channel models, and the reference minimum LLR is the minimum of the LLRs determined in the multiple channel models. That is, the BS searches for a reference minimum LLR corresponding to the MIMO mode of the MS, the modulation scheme of the MS, and the minimum SINR determined in step 213. [

Then, the BS proceeds to step 217 and compares the measured average LLR and the reference minimum LLR. As a result of the comparison, if the measured average LLR is less than the reference minimum LLR, the BS determines that the UE has not transmitted a signal. Accordingly, the BS determines that the UE has failed to receive the uplink resource allocation IE, and proceeds to step 219 to retransmit the uplink resource allocation IE to the UE. In this case, according to another embodiment of the present invention, the BS can recover resources allocated to the UE. On the other hand, if the measured average LLR is equal to or greater than the reference minimum LLR, the BS determines that the UE has transmitted a signal but has failed to decode the data. Accordingly, the BS proceeds to step 221 and transmits a NACK to the UE.

FIG. 3 illustrates a procedure for determining whether a base station receives a map to a terminal in a broadband wireless communication system according to a second embodiment of the present invention.

Referring to FIG. 3, in step 301, the BS determines an initial SINR of a mobile station using a CQI signal received from a mobile station. The initial SINR is information used for uplink scheduling for the UE. The CQI signal is a signal for the UE to report the downlink channel quality, and the terminal must transmit the CQI signal as long as it is connected to the base station. Here, the CQI signal includes one of sequences having orthogonality or quasi orthogonality. Therefore, the base station detects the sequence included in the CQI signal through correlation calculation, and determines the SINR value indicated by the detected sequence as the initial SINR of the UE.

In step 303, the BS determines a MIMO mode and a modulation scheme of the MS based on the initial SINR, and then allocates a resource. The MIMO mode, the modulation scheme, and an uplink resource And transmits the allocation IE to the terminal. In this case, the resource allocation IE may be a fixed resource allocation IE for allocating or changing fixed resources, a synchronous retransmission resource allocation IE for changing a retransmission resource in a synchronous retransmission scheme, a random resource allocation IE, or the like.

After transmitting the uplink resource allocation IE, the BS proceeds to step 305 and attempts to receive the signal of the UE in the resource allocated by the uplink resource allocation IE. In other words, the base station extracts signals mapped to the sub-carriers included in the allocated resource, performs demodulation and channel decoding, and then performs a CRC check.

In step 307, the BS checks the CRC check result. That is, the BS determines whether the CRC check is successful or unsuccessful. If the CRC check is successful, the BS proceeds to step 309 to receive a signal from the UE, determine that data decoding is successful, and transmit an ACK to the UE. On the other hand, if the CRC check fails, the base station performs steps 311 to 315 to determine whether the terminal has not transmitted a signal or has transmitted a signal but has failed in decoding.

That is, if the CRC check fails, the BS proceeds to step 311 and determines the measured SINR of the allocated resource. The measurement SINR means a SINR value for the signal measured under the assumption that the terminal transmits a signal through the allocated resource. That is, the BS measures an SINR with respect to a signal received through a resource allocated to the MS, on the assumption that the MS transmits a signal. Specifically, the base station determines the measured SINR by measuring the SINR of each of the tones and averaging the per-tone SINR (SINR). According to another embodiment of the present invention, the base station may utilize RBIR mapping to reflect the influence of tones with a low SINR. Specifically, the BS measures the per-tone SINR and then obtains an RBIR value corresponding to the corresponding SINR using the value of the SINR to RBIR mapping table (SINR to RBIR mapping table). For example, the mapping table is shown in Table 5 below. Then, the base station determines an average RBIR by averaging the RBIR values of each tone, and determines a measured SINR by searching the mapping table again for the SINR corresponding to the average RBIR.

After determining the measured SINR, the BS proceeds to step 313 and determines a minimum received SINR. Herein, the minimum SINR means a minimum SINR measured when a mobile station transmits a signal. For example, the minimum SINR may be determined using the initial SINR, the maximum number of retransmissions, and the SINR increase per retransmission, determined in step 301. [ For example, the BS determines the minimum SINR by subtracting a product of the maximum retransmission number and the SINR increase value from the initial SINR, as shown in Equation (5).

Thereafter, the BS proceeds to step 315 and compares the measured SINR and the minimum received SINR. As a result of the comparison, if the measured SINR is less than the minimum received SINR, the base station determines that the terminal has not transmitted a signal. Accordingly, the BS determines that the UE has not received the uplink resource allocation IE, and proceeds to step 317 to retransmit the uplink resource allocation IE to the UE. In this case, according to another embodiment of the present invention, the BS can recover resources allocated to the UE. On the other hand, if the measured SINR is greater than or equal to the minimum SINR, the BS determines that the UE has transmitted a signal but has failed to decode the data. Accordingly, the BS proceeds to step 319 and transmits a NACK to the UE.

4 illustrates a block diagram of a base station in a broadband wireless communication system according to an embodiment of the present invention.

4, the base station includes a subcarrier mapping unit 402, an OFDM modulation unit 404, an RF (Radio Frequency) transmission unit 406, an RF reception unit 408, an OFDM demodulation unit 410, A demapping unit 412, a data processing unit 414, a message generating unit 416, a message analyzing unit 418, an initial SINR determining unit 420, and a control unit 422.

The subcarrier mapping unit 402 maps the data signals provided from the data processing unit 414 and the message signals provided from the message generation unit 416 to subcarriers. The OFDM modulator 404 converts the signals mapped to the subcarriers into a time domain signal through an Inverse Fast Fourier Transform (IFFT) operation, and constructs OFDM symbols by inserting a CP (Cyclic Prefix). The RF transmitter 406 up-converts the OFDM symbols to an RF band signal, and then transmits the RF band signal through an antenna. The RF receiver 408 converts an RF band signal received through an antenna into a baseband signal. The OFDM demodulator 410 divides the baseband signal into OFDM symbol units, removes the CP, and restores the signals for each subcarrier through an FFT (Fast Fourier Transform) operation. The sub-carrier demapping unit 412 divides the signals for each sub-carrier into processing units. The subcarrier demapping unit 412 provides the data signals to the data processing unit 414 and the message signals to the message interpreting unit 416.

The data processor 414 reconstructs the received data bit stream by demodulating and channel decoding the data signals, and generates transmission data signals by channel-coding and modulating the transmitted data bit stream. For example, when restoring the received data bit stream, the data processing unit 414 calculates bit-by-bit LLR values for the received signals and determines the received data bit stream using the LLR values. The data processing unit 414 performs a CRC check on the received data bit stream and informs the controller 422 of the CRC check result. In this case, according to the first embodiment of the present invention, the data processing unit 414 provides the LLR values to the controller 422. [

The message analyzing unit 418 recovers a message bit string from the message signals received from the terminal. The message analyzing unit 418 analyzes the message bit string to confirm the information included in the message and provides the checked information to the controller 422. [ The message generator 416 constructs a message bit string including information provided from the controller 422, and generates physical message signals from the message bit string. For example, the message generator 416 generates an ACK indicating a successful decoding of uplink data and a NACK indicating a failure. Also, the message generator 416 generates a map message informing the resource allocation result. That is, a resource allocation IE is created according to a resource scheduling result provided from the controller 422. The message generator 416 separates and codes the resource allocation IE using a unique sequence of a terminal to receive the resource allocation IE. For example, the message generator 416 generates a fixed resource allocation IE for allocating or changing fixed resources, a synchronous retransmission resource allocation IE for changing a retransmission resource in a synchronous retransmission scheme, a random resource allocation IE, and the like .

The initial SINR decision unit 420 receives the CQI signal received through the CQI channel from the subcarrier demapping unit 412 and determines the initial SINR of the terminal using the CQI signal. The CQI signal is a signal for the UE to report the downlink channel quality, and the terminal must transmit the CQI signal as long as it is connected to the base station. Here, the CQI signal includes one of sequences having orthogonality or quasi orthogonality. Therefore, the initial SINR determining unit 420 detects a sequence included in the CQI signal through correlation calculation, and determines the SINR value indicated by the detected sequence as the initial SINR of the UE. The initial SINR determining unit 420 informs the control unit 422 of the initial SINR.

The controller 422 controls the overall function of the base station. For example, the control unit 422 controls the sub-carrier demapping unit 412 to extract data signals for each UE according to a resource allocation result, and performs sub-carrier mapping for mapping data signals for each UE according to the resource allocation result (402). The control unit 422 performs processing corresponding to the information confirmed by the message analyzing unit 418 and provides the message generating unit 416 with information included in the transmission message. The control unit 422 controls the message generating unit 416 to generate the ACK when the data decoding unit 414 is informed that the data decoding is successful, And controls the message generator 416 to generate the NACK. However, according to the embodiment of the present invention, if the data decoding failure is notified, the controller 422 determines whether or not the MAP of the terminal is received, and generates the NACK if it is determined that the MAP has been received . On the other hand, when it is determined that the UE has not received the MAP, the controller 422 controls the UE to retransmit the UL resource allocation IE or reclaims resources allocated to the UE.

The controller 422 includes a scheduler 424 for allocating resources to the terminal and a map reception determiner 426 for determining whether the terminal has successfully received a map. The scheduler 424 determines a MIMO mode and a modulation scheme of the UE based on the initial SINR determined by the initial SINR determiner 420, and then allocates resources. At this time, the scheduler 424 can allocate resources according to a fixed allocation scheme, and can change or cancel fixed allocation resources. In addition, the scheduler 424 may change resources for retransmission allocated to the same location as the resources for initial transmission according to the synchronous retransmission scheme.

The MAP reception determination unit 426 determines whether the UE has received an uplink resource allocation IE, i.e., an uplink map, using a signal received through the uplink resource allocated to the UE. In detail, the map reception determination unit 426 determines whether or not the uplink map is received by determining whether a signal is received through the resource allocated to the terminal. The map reception determination unit 426 operates when the data processing unit 414 is notified of decoding failure of the uplink data. The detailed configuration and operation of the map reception determination unit 426 will be described below with reference to FIGS. 5A and 5B.

FIG. 5A illustrates a block configuration of the map reception determination unit 426 in the broadband wireless communication system according to the first embodiment of the present invention.

5A, the map reception determination unit 426 includes a minimum reception SINR calculation unit 502, a table storage unit 504, a reference minimum LLR determination unit 506, a measured average LLR calculation unit 508 And a magnitude comparison unit 510. [

The minimum SINR calculator 502 determines a minimum SINR for the MS. Herein, the minimum received SINR means a minimum SINR measured when the terminal transmits a signal. For example, the minimum SINR may be determined using the initial SINR, the maximum number of retransmissions, and the SINR increase per retransmission determined by the initial SINR determiner 420. [ For example, the minimum SINR calculator 502 determines the minimum SINR by subtracting a product of the maximum retransmission number and the SINR increase value from the initial SINR, as shown in Equation (4).

The table storage unit 504 stores a table including reference minimum LLRs for determining whether a terminal receives a map. The table includes the MIMO mode, the modulation scheme and the minimum received SINR as lookup parameters, and includes LLR values determined by pre-simulation. The reference minimum LLR is a reference LLR value for determining whether a map is received or not, and is searched in a table stored in the table storage unit 504. The simulations are conducted under conditions of various channel models, and the reference minimum LLR is the minimum of the LLRs determined in the multiple channel models.

The reference minimum LLR determining unit 506 determines a reference minimum LLR for determining whether to receive the map of the terminal. That is, the BS searches for a reference minimum LLR corresponding to the MIMO mode of the MS, the modulation scheme of the MS, and the minimum SINR determined in step 213. [

The measured average LLR calculating unit 508 determines a measured average LLR for the signal received from the resource allocated to the terminal. Here, the measured average LLR means an average value of absolute values of LLR values per bit of all tones calculated under the assumption that the terminal transmits a signal. That is, the measured average LLR calculating unit 508 calculates an average value of absolute values of the LLR values provided from the data processing unit 414.

The size comparing unit 510 compares the measured average LLR and the reference minimum LLR, and determines whether the terminal receives the map according to the comparison result. If the measured average LLR is smaller than the reference minimum LLR as a result of the comparison, the size comparator 510 determines that the mobile station has not transmitted a signal. On the other hand, if the measured average LLR is equal to or greater than the reference minimum LLR, the size comparator 510 determines that the UE has transmitted a signal but has failed to decode the data.

5B shows a block configuration of the map reception determination unit 426 in the broadband wireless communication system according to the second embodiment of the present invention.

As shown in FIG. 5B, the map reception determination unit 426 includes a minimum SINR calculation unit 552 and a measurement SINR determination unit 554.

The minimum SINR calculator 552 determines a minimum SINR for the MS. Herein, the minimum received SINR means a minimum SINR measured when the terminal transmits a signal. For example, the minimum SINR may be determined using the initial SINR, the maximum number of retransmissions, and the SINR increase per retransmission determined by the initial SINR determiner 420. [ For example, the minimum SINR calculator 552 determines the minimum SINR by subtracting the product of the maximum number of retransmissions and the SINR increase in the initial SINR, as shown in Equation (4).

The measurement SINR determination unit 554 determines a measured SINR at a resource allocated to the UE. The measurement SINR means a SINR value for the signal measured under the assumption that the terminal transmits a signal through the allocated resource. That is, the measurement SINR determining unit 554 measures SINR with respect to a signal received through a resource allocated to the terminal, on the assumption that the terminal transmits a signal. More specifically, the measured SINR determining unit 554 determines the measured SINR by measuring the SINR of each of all the tones and averaging the per-tone SINR (SINR). According to another embodiment of the present invention, the measurement SINR determiner 554 may utilize the RBIR mapping to reflect the influence of the tone with a low SINR. More specifically, the measured SINR determining unit 554 measures the SINR for each tone, and then obtains an RBIR value corresponding to the corresponding SINR using the value of the SINR to RBIR mapping table (SINR to RBIR mapping table). For example, the mapping table is shown in Table 5 below. Then, the measured SINR determining unit 554 determines an average RBIR by averaging the RBIR values of each tone, and determines a measured SINR by searching the mapping table again for the SINR corresponding to the average RBIR.

The size comparing unit 556 compares the measured SINR and the minimum received SINR, and determines whether the terminal receives the map according to the comparison result. As a result of the comparison, if the measured SINR is smaller than the minimum received SINR, the size comparator 556 determines that the UE has not transmitted a signal. On the other hand, if the measured SINR is equal to or greater than the minimum SINR, the size comparator 556 determines that the UE has transmitted a signal but has failed to decode the data.

Each of the blocks shown in FIG. 4 to FIG. 5B is defined by functional classification in order to clarify convenience and technical characteristics. Therefore, in the case of implementing the present invention, hardware may be configured differently from those shown in FIG. 4 to FIG. 5B. For example, a plurality of blocks may be composed of one integrated circuit, or one block may be included in a plurality of circuits.

The technique of determining whether a terminal receives a map according to the embodiment of the present invention described with reference to FIG. 2 to FIG. 5B may be applied to an uplink map, i.e., an uplink resource allocation IE. At this time, the uplink resource allocation IE includes a fixed resource allocation IE, a synchronous retransmission resource allocation IE, and a random resource allocation IE. However, according to the intention of the inventor of the present invention, the present invention can be applied only to a specific kind of resource allocation IE. For example, the present invention can be applied only to the fixed resource allocation IE and the synchronous retransmission resource allocation IE, because the validity of the resource allocation information is maintained for a period of several frames. This is because the validity of the resource allocation information is maintained for a period of several frames, so that the necessity of recognizing the failure of reception of a map by the terminal is relatively larger. However, the present invention is not limited to the fixed resource allocation IE and the synchronous retransmission resource allocation IE, and can also be applied to a temporary resource allocation IE.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various modifications within the scope of the invention. Therefore, the scope of the present invention should not be limited by the illustrated embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

1 is a diagram illustrating a frame structure of a broadband wireless communication system according to an embodiment of the present invention;

2 is a diagram illustrating a procedure for determining whether a base station receives a map to a terminal in a broadband wireless communication system according to a first embodiment of the present invention;

3 is a diagram illustrating a procedure for determining whether a base station receives a map to a terminal in a broadband wireless communication system according to a second embodiment of the present invention;

4 is a block diagram of a base station in a broadband wireless communication system according to an embodiment of the present invention.

5A is a block diagram of a map reception determination unit in a broadband wireless communication system according to a first embodiment of the present invention.

5B is a block diagram of a map reception determination unit in a broadband wireless communication system according to a second embodiment of the present invention.

Claims (18)

A method of operating a base station in a broadband wireless communication system, Comprising the steps of: transmitting a resource allocation IE (information element) Calculating a value related to the strength of the signal through the allocated resource to check whether a signal received from the terminal is transmitted using the allocated resource; And transmitting the resource allocation IE to notify the terminal of the allocated resource again if the calculated value is smaller than the reference value. The method according to claim 1, Wherein the calculated value is one of a signal-to-interference plus noise ratio (SINR), a carrier-to-interference plus noise ratio (CINR), or a signal to noise ratio (SNR). The method according to claim 1, The signal comprising a plurality of bits, Wherein the calculated value is calculated by averaging absolute values of LLR (log likelihood ratio) values for each of at least one bit corresponding to the allocated resource among the plurality of bits, The reference value, An LLR value calculated based on a minimum received channel quality value, Wherein the minimum received channel quality value is a specified value or is determined based on a channel quality indicator (CQI) received from the terminal. The method of claim 3, Wherein the reference value is determined based on at least one of a multiple input multiple output (MIMO) mode applied to the UE, a modulation scheme applied to the UE, and a minimum received channel quality value, Wherein the minimum received channel quality value is calculated by subtracting the product of the maximum number of retransmissions and the increment of the channel quality value per retransmission from the initial channel quality value used for uplink scheduling for the UE. The method of claim 3, The reference value is calculated by searching at least one of a MIMO mode applied to the UE, a modulation scheme applied to the UE, and the minimum received channel quality value in a predefined table as a look-up parameter Way. The method according to claim 1, The calculated value is a value The average value of the channel quality values for the portion of the signal received via the allocated resource, Wherein the reference value is a specified value or is calculated based on a channel quality indicator (CQI) received from the terminal. The method of claim 6, Wherein the average value of the channel quality values is calculated using the channel quality values and a received bit mutual information rate (RBIR) mapping table. The method of claim 6, The reference value is calculated by subtracting the product of the maximum number of retransmissions and the increment of the channel quality value per retransmission from the initial channel quality value calculated based on the CQI value, The initial channel quality value may be expressed as: Wherein the method is used for uplink scheduling for the UE. The method according to claim 1, And transmitting a non-acknowledgment (NACK) message if the calculated value is greater than or equal to the reference value. A base station apparatus in a broadband wireless communication system, A transmitting unit; And a control unit, Wherein the transmitter is configured to transmit a resource allocation IE (information element) for notifying the resource allocated to the terminal, The control unit And to calculate a value related to the strength of the signal through the allocated resource to determine whether a signal received from the terminal is transmitted using the allocated resource, Wherein the transmitter is configured to transmit the resource allocation IE to notify the terminal of the allocated resources again when the calculated value is smaller than the reference value. The method of claim 10, Wherein the calculated value is one of a signal-to-interference plus noise ratio (SINR), a carrier-to-interference plus noise ratio (CINR), or a signal to noise ratio (SNR). The method of claim 10, The signal comprising a plurality of bits, Wherein the calculated value is calculated by averaging absolute values of LLR (log likelihood ratio) values for each of at least one bit corresponding to the allocated resource among the plurality of bits, The reference value, An LLR value calculated based on a minimum received channel quality value, Wherein the minimum received channel quality value is a specified value or is determined based on a channel quality indicator (CQI) received from the terminal. The method of claim 12, Wherein the reference value is determined based on at least one of a multiple input multiple output (MIMO) mode applied to the UE, a modulation scheme applied to the UE, and a minimum received channel quality value, Wherein the minimum received channel quality value is calculated by subtracting a product of an initial retransmission count and an increment of a channel quality value per retransmission from an initial channel quality value used for uplink scheduling for the UE. The method of claim 12, The reference value is calculated by searching at least one of a MIMO mode applied to the UE, a modulation scheme applied to the UE, and the minimum received channel quality value in a predefined table as a look-up parameter. . The method of claim 10, The calculated value is a value The average value of the channel quality values for the portion of the signal received via the allocated resource, Wherein the reference value is a specified value or is calculated based on a channel quality indicator (CQI) received from the terminal. 16. The method of claim 15, Wherein the average value of the channel quality values is calculated using the channel quality values and a received bit mutual information rate (RBIR) mapping table. 16. The method of claim 15, The reference value is calculated by subtracting the product of the maximum number of retransmissions and the increment of the channel quality value per retransmission from the initial channel quality value calculated based on the CQI, And for uplink scheduling of the UE to the UE. The method of claim 10, The transmitter may further comprise: And to send a non-acknowledge (NACK) message if the calculated value is greater than or equal to the reference value.

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