KR20100061967A - Apparatus and method for processing bandwidth request in a communication system - Google Patents

Abstract

PURPOSE: A device for processing a bandwidth request in a communication system and a method thereof are provided to transmit upward link data more steadily in a feeble electric field situation. CONSTITUTION: A power per subcarrier is calculated considering a channel status(200). A assignable subcarrier number is calculated considering the maximum transmission power of a terminal(202). A sub-channel number is calculated using the assignable subcarrier number(204). A data transfer rate capable of being aligned in the sub-channel number is calculated(206). A bandwidth request is transmitted to a base station considering the data transfer rate capable of being aligned in the sub-channel number(208).

Description

Apparatus and method for processing bandwidth request in communication system {APPARATUS AND METHOD FOR PROCESSING BANDWIDTH REQUEST IN A COMMUNICATION SYSTEM}

The present invention relates to a bandwidth request considering a maximum transmission power of a terminal in a communication system, and more particularly, to an apparatus and method for reaching a maximum throughput while increasing a reception rate of data by making a bandwidth request considering a wireless channel situation.

Through a ranging process in a broadband wireless communication system, an accurate timing offset is obtained so that transmission of a terminal is aligned at a sample time. The ranging is divided into initial ranging, periodic ranging, bandwidth request ranging, and handoff ranging. Among these, the bandwidth request ranging is used as a means for requesting a resource required for transmitting traffic in the uplink from the terminal. To this end, the base station broadcasts the CDMA code information used for the bandwidth request ranging as the system information in the uplink channel descriptor (UCD). In addition, the base station broadcasts information on uplink resources to be used by the terminal to transmit the bandwidth request code to all the terminals in UL-MAP.

1 illustrates a bandwidth request ranging procedure in a broadband wireless communication system. Referring to FIG. 1, the bandwidth request ranging method is as follows. When the uplink traffic occurs, the UE performs bandwidth request ranging to transmit the uplink traffic, and selects one of the bandwidth request codes included in the UCD and uses the resource allocated to the UL-MAP to select the bandwidth request code. The code is transmitted to the base station in a competitive manner (110). Subsequently, the base station that successfully receives the bandwidth request code without collision has a frame number of the bandwidth request code received from the terminal, subchannel information, the received bandwidth request code number, and the bandwidth required for the terminal to transmit a bandwidth request header. The allocation information is included in the CDMA_Allocation_IE of the UL-MAP and broadcasted (120). Subsequently, the terminal compares the frame number, subchannel information, and bandwidth request code number of CDMA_Allocation_IE included in the UL-MAP with the information transmitted by the terminal for bandwidth request ranging, and uses uplink resources allocated from the base station. In step 130, the bandwidth request header is transmitted. Here, the bandwidth request header includes resource information necessary for the terminal to transmit uplink traffic. Subsequently, when the base station receives the bandwidth request header, the base station allocates an uplink resource to the resource requested by the terminal and broadcasts this information through the UL-MAP (140). When the terminal receives the requested resource through the UL-MAP, the uplink traffic is allocated. Transmit (150).

As described above, the terminal requests the uplink bandwidth to the base station to transmit the uplink data. The requested bandwidth is determined by the scheduler of the UE, and the amount is determined in consideration of the minimum reserved data rate of each traffic connection and the amount of messages to be sent to the signaling connection. do. In the Orthogonal Frequency Division Multiple Access (OFDMA) system, the UE transmit power is not transmitted when data is mapped to all subcarriers, but when data is not mapped to some subcarriers, a transmission to be allocated to an empty subcarrier. Power can be allocated to subcarriers mapped to actual data. This is because the power can be increased by digitally increasing the amplitude of the actual data inside the baseband modem.

In the prior art, the terminal requests a bandwidth based on the total sum of higher data to be transmitted in each connection. In order to satisfy the Quality of Service (QoS), a bandwidth for satisfying a minimum data rate of each connection is requested. However, since the bandwidth request is based on higher data, the terminal transmission power may be insufficient in a weak electric field (eg, a channel condition at a cell boundary). Therefore, an error occurs in uplink data in a weak electric field situation, so that the base station cannot receive it.

Accordingly, an object of the present invention is to provide an apparatus and method for performing a bandwidth request for a terminal to stably transmit data at a cell boundary in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for requesting a base station by calculating a bandwidth in consideration of a channel situation in a wireless communication system.

According to a first aspect of the present invention for achieving the above object, a method for performing a bandwidth request in a wireless communication system, the process of calculating the power per subcarrier in consideration of the channel situation, the maximum power available of the terminal Calculating the number of assignable subcarriers in consideration of the amount, calculating the number of assignable subchannels using the number of assignable subcarriers, and requesting the base station for the number of subchannels.

According to a second aspect of the present invention for achieving the above objects, an apparatus for performing a bandwidth request in a wireless communication system, the power calculation unit for calculating the power per subcarrier in consideration of the channel situation, the maximum of the terminal A subcarrier calculator that calculates the number of subcarriers that can be allocated in consideration of power capacity, a subchannel calculator that calculates the number of assignable subchannels by using the number of assignable subcarriers, and the base station by using the number of subchannels It characterized in that it comprises a transmission unit for requesting.

In the present invention, when the terminal requests uplink bandwidth to the base station, the uplink data can be transmitted more stably even in the weak field situation by considering not only the QoS parameter and the uplink data waiting in the transmission queue but also the channel condition. In the situation, the uplink data transmission is not suddenly stopped in the terminal, but stable uplink data transmission is possible in a weak electric field situation at a low data rate.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed descriptions of related well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intentions or customs of the user, the operator, and the like. Therefore, the definition should be made based on the contents throughout the specification.

Hereinafter, an apparatus and method for requesting a base station by calculating a bandwidth in consideration of a channel situation in a wireless communication system will be described.

2 is a flowchart illustrating an operation of a terminal for a terminal to calculate a bandwidth and request a base station in a wireless communication system according to an exemplary embodiment of the present invention. Herein, the allocation area for uplink data is 15 symbols, and the base station uses uplink partial usage of subcarriers (PUSC) and assumes that 24 subcarriers x 3 symbols are the minimum allocation units.

Referring to FIG. 2, the terminal calculates power per subcarrier in consideration of a channel condition in step 200. That is, the terminal considers the current signal-to-noise ratio (e.g., Ccarrier-to-Interference-and-Noise Ratio (CINR), path loss, uplink modulation, etc.) in consideration of power per subcarrier. The power calculation per subcarrier is shown in Equation 1 below in the IEEE 802.16e standard.

Here, P (dbm) is a transmission power per subcarrier of the terminal, and L is a path loss (uplink propagation loss), calculated by subtracting RSSI (Received Signal Strength Indication) from the effective isotropically radiated power (EIRP) of the base station. do. The C / N is a normalized CINR, and basically the value in the specification is applied. R is set to a repetition code value included in UL_Map_IE. The NI is noise and interference per subcarrier. The Offset_SS is a power offset determined by the terminal (initial value is 0), and the Offset_BS is a power offset determined by the base station.

In step 202, the terminal calculates the number of subcarriers that can be allocated in consideration of the maximum transmission power. At this time, it is calculated how many subcarriers can be allocated within a range not exceeding the maximum transmission power of the terminal.

For example, assuming that the maximum transmission power of the terminal is 23 dBm, the number of subcarriers that can be allocated is expressed by Equation 2 below.

,

That is, the largest integer n that satisfies n <= 2 ^ k is calculated to calculate the maximum number of subcarriers that can be transmitted at the maximum transmission power.

That is, if the maximum transmission power of the terminal is 23mW and the power per subcarrier is 1mW, the total allowable number of subcarriers of the terminal is 23.

In step 204, the terminal calculates how many subchannels can be allocated in consideration of a subchannel which is a resource allocation unit of the base station. The number of subchannels that can be allocated is shown in Equation 3 below. Assume a subchannel consists of 24 subcarrier x 3 symbols.

Here, s is the number of subchannels that can be allocated at the same frequency, n is the maximum number of subcarriers that can be transmitted, m is the number of subchannels allocated on the time axis, and [x] represents the maximum integer smaller than x. If an allocation area for uplink data is 15 symbols in size, m is 5 in a subchannel having 3 symbols in size.

Thereafter, in step 206, the terminal calculates a data rate that can be allocated to the number of subchannels (s) that can be allocated according to the modulation scheme. Compare the amount of data and make a bandwidth request with the smaller of the two values.

The procedure of the present invention is then terminated.

3 illustrates an apparatus for requesting a base station by calculating a bandwidth in consideration of a channel situation in a wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the device for making a bandwidth request includes a power calculator 300, a subcarrier calculator 302, a subchannel calculator 304, a rate calculator 306, and a bandwidth requester 308. It is configured to include.

The power calculator 300 calculates power per subcarrier in consideration of a channel condition. That is, the power calculator 300 receives system information such as signal-to-noise ratio (eg, Ccarrier-to-Interference-and-Noise Ratio (CINR), path loss, and uplink modulation). Calculate the power per subcarrier.

The subcarrier calculator 302 receives the power value per subcarrier from the power calculator 300 and calculates the number of assignable subcarriers in consideration of the maximum transmission power. At this time, it is calculated how many subcarriers can be allocated within a range not exceeding the maximum transmission power of the terminal.

The subchannel calculator 304 calculates how many subchannels can be allocated in consideration of a subchannel which is a resource allocation unit of a base station.

The rate calculator 306 calculates a data rate that can be allocated to an assignable number of subchannels s according to a modulation scheme, and the bandwidth requester 308 can assign data to the assignable number of subchannels s. The bandwidth request is made by comparing the data rate with the data amount of the current buffer.

4 shows an example of the configuration of a subcarrier and a subchannel in a frame according to the present invention.

Referring to FIG. 4, the horizontal axis of the frame is a time domain, and 0 to 14 indexes are symbol indexes, and the vertical axis of the frame is a frequency domain, 0 to 55 indexes are subcarrier indexes.

Assuming that one subchannel consists of 24 subcarrier x 3 symbols, the first subchannel 400, the second subchannel 410, the third subchannel 430, and the fourth subchannel ( 440).

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a diagram illustrating a bandwidth request ranging procedure in a broadband wireless communication system;

2 is a flowchart illustrating a terminal operation for requesting a base station by calculating a bandwidth in consideration of a channel situation in a wireless communication system according to an embodiment of the present invention;

3 is a diagram illustrating an apparatus for requesting a base station by calculating a bandwidth in consideration of a channel situation in a wireless communication system according to an embodiment of the present invention;

4 is a configuration diagram of a subcarrier and a subchannel in a frame according to the present invention.

Claims (6)

A method for performing a bandwidth request in a wireless communication system, Calculating power per subcarrier in consideration of channel conditions; Calculating the number of subcarriers that can be allocated in consideration of the maximum transmission power of the terminal; Calculating a number of subchannels by using the assignable number of subcarriers; And requesting a bandwidth from a base station in consideration of a data rate allocable to the number of subchannels. The method of claim 1, Calculating a data rate assignable to the number of subchannels. The method of claim 1, When the bandwidth request, comparing the amount of data allocated to the number of sub-channels with the amount of data of the current buffer, and requesting a bandwidth corresponding to a small transmission rate. An apparatus for performing a bandwidth request in a wireless communication system, A power calculation unit calculating power per subcarrier in consideration of a channel situation; A subcarrier calculator for calculating an assignable number of subcarriers in consideration of a maximum transmit power of a terminal; A subchannel calculator for calculating the number of subchannels by using the assignable subcarriers; And a bandwidth request unit for making a bandwidth request to a base station in consideration of a data rate allocable to the number of subchannels. The method of claim 4, wherein And a rate calculator for calculating a data rate that is assignable to the number of subchannels. The method of claim 4, wherein The bandwidth request unit And requesting a bandwidth corresponding to a small data rate when comparing the bandwidth with the amount of data allocated to the number of subchannels and the amount of data in a current buffer.

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