KR20030058589A - Method for Allocating Ranging Interval and Ranging Sub-channel for Initial Ranging in OFDMA System - Google Patents

Abstract

PURPOSE: A ranging interval and ranging sub channel allocation method for initial ranging of an orthogonal frequency division multiple access(OFDMA) system is provided, which reduces ICI(Inter-Channel Interference) between ranging signals in a TDD mode OFDMA wireless communication system. CONSTITUTION: According to the method for allocating ranging interval for initial ranging with a subscriber station in a base station of a multi user orthogonal frequency division multiple access(OFDMA) wireless communication system, a receiving interval of an initial ranging signal is determined by reflecting maximum delay predicted while transmitting and receiving data with the subscriber station. System information required in the initial ranging including the determined receiving interval are broadcasted to all subscriber stations in a cell through a broadcasting channel. And the initial ranging signal from the subscriber stations is received in correspondence to the system information as to all symbols received from the subscriber stations in the determined receiving interval.

Description

Method for Allocating Ranging Interval and Ranging Sub-channel for Initial Ranging in OFDMA System for Initial Ranging of Orthogonal Frequency Division Multiple Access System

The present invention is a wireless communication system of Orthogonal Frequency Division Multiple Access (hereinafter referred to as " OFDMA ") in a point-to-multipoint Broadband Wireless Access (BWA) system. In particular, the present invention relates to a ranging interval and ranging subchannel allocation method for initial ranging of the multi-user OFDMA wireless communication system.

In IEEE 802.16ab, an OFDMA wireless communication system uses a microwave frequency band between 2 GHz and 11 GHz to transfer data between a base station (BS) or BS (subscriber station). It is defined to be transferable. Such an OFDM wireless communication system can be defined by a two-dimensional access method combining a time division access and a frequency division access technology. Each OFDMA symbol is carried on a subcarrier and bound to a predetermined sub channel. Ranging in the OFDMA wireless communication system as described above periodically performs an accurate time offset between the base station and the subscriber station and corrects power. Ranging for this purpose is defined as three types as follows.

Initial Ranging

2. Bandwidth Request Ranging

3. Maintenance Ranging]

The initial ranging is a long ranging scheme in which two SSs are transmitted in two OFDM symbols when the SS in the BS establishes a new call with the BS. Management ranging is a short ranging method using one OFDM symbol in the initial ranging state. Thus, the initial ranging is performed in an initial state in which transmission power and time offsets are not adjusted between the base station and the subscriber station. Thereafter, the SS can be transmitted in synchronization with a symbol indicating the start of a burst boundary at a predetermined power required in the OFDMA wireless communication system. This initial ranging procedure is described with reference to FIG. 5 as follows.

First, when the base station transmits system information necessary for initial ranging, that is, time offset, interval ID, etc. to the subscriber station, the subscriber station arbitrarily selects one ranging code with reference to the information for the initial ranging and transmits it to the base station. do. When the base station detects a signal transmitted from the subscriber station, the base station transmits time control information and power control information to the subscriber station using the randomly selected code. The subscriber station performs time adjustment and power control with reference to the time control information and power control information. At this time, the transmission time of the data transmitted from the subscriber station and the power measurement at that time are performed by several sub-channels allocated to the ranging sub-channels, and each user has a binary code bank set as the ranging code. A code is randomly selected from and transmitted to a randomly selected ranging subchannel.

Meanwhile, the channel structure of the FDD mode OFDMA wireless communication system for transmitting the ranging information is shown in FIG.

Referring to FIG. 1, two “subchannels” among “subchannels” including 53 carriers are always set as ranging subchannels and broadcasted to respective users in a cell. Each user in the cell uses the ranging subchannel when ranging is necessary. However, in this channel structure, it can be seen that only a carrier is used differently in the same time zone as the ranging transmission signal and the data transmission signal for controlling time offset and transmission power. This causes a problem of generating inter-channel interference (hereinafter referred to as "ICI") between the signal for ranging transmission and the signal for data transmission.

To solve this problem, the channel structure of another TDD mode OFDMA wireless communication system is shown in FIG. 2. As shown in FIG. 2, the ranging signal section for precisely controlling time offset and transmission power and the signal section for data transmission are separated in time so that only the ranging information is received in the receiving section of the ranging signal. On the other hand, in the transmission and reception period of the data signal it is possible to perform the transmission and reception of the data. That is, periodically all subchannels of a predetermined size are allocated for ranging so that each user in the BS uses a racing subchannel in the lasing interval if necessary.

However, the channel structure of the TDD mode OFDMA wireless communication system has a problem in that ICI occurs between the ranging symbols when performing initial ranging without adjusting the transmission power and time offset between the base station and the subscriber station.

In addition, in the channel structure of the TDD mode OFDMA wireless communication system, if the interval for receiving the response signal from the subscriber station for the initial ranging is too small or large, the ranging signal and the data may be out of the reception range of the initial ranging signal. There was a problem inducing ICI between the transmission and reception signals or reducing channel resource efficiency.

Accordingly, an object of the present invention for solving the above problems is ranging interval and ranging unit for initial ranging in OFDMA wireless communication system to reduce ICI between ranging signals in TDD mode OFDMA wireless communication system. The present invention provides a channel allocation method.

Another object of the present invention is to assign ranging intervals and ranging subchannels for initial ranging in an OFDMA wireless communication system in which an initial ranging response signal transmitted from a subscriber station can be reliably received within a reception interval set by a base station. In providing a method.

It is still another object of the present invention to provide a ranging interval and ranging subchannel allocation method for initial ranging in an OFDMA wireless communication system which enables a subscriber station to perform a transmission operation in advance of a predetermined transmission time by a processing delay of the subscriber station. In providing.

In a first aspect for achieving the above object, the present invention provides a method for allocating a ranging interval for initial ranging with a subscriber station in a base station of a multi-user orthogonal frequency division multiple access wireless communication system. Determining a reception interval of an initial ranging signal by reflecting a maximum delay expected when data is transmitted and received with the subscriber station, and including system information necessary for initial ranging, including the determined reception interval, through a predetermined broadcast channel. Broadcasting to all subscriber stations in the cell and receiving initial ranging signals from the subscriber stations in response to the system information for all symbols received from the subscriber station in the determined reception interval. It is characterized by.

In a second aspect for achieving the above object, the present invention provides a method for transmitting a ranging signal for initial ranging with a base station in a subscriber station of a multi-user orthogonal frequency division multiple access wireless communication system. Receiving, from the base station, system information necessary for initial ranging including a reception period of the ranging signal through a predetermined broadcast channel, and determining an arbitrary ranging subchannel and a ranging code from the system information; Adjusting a transmission time of an initial ranging signal in consideration of a processing delay time for initial ranging, and transmitting the initial ranging signal by the ranging subchannel and the ranging code at the adjusted transmission time. It is characterized by including.

In a third aspect for achieving the above object, the present invention provides a method for transmitting ranging signals for initial ranging with a base station in a subscriber station of a multi-user orthogonal frequency division multiple access wireless communication system. Receiving, from the base station, system information necessary for initial ranging including a reception period of the ranging signal through a predetermined broadcast channel, and determining an arbitrary ranging subchannel and a ranging code from the system information; Adjusting a transmission time of an initial ranging signal in consideration of a processing delay time for initial ranging, and transmitting the initial ranging signal by the ranging subchannel and the ranging code at the adjusted transmission time. It is characterized by including.

1 is a channel structure of a typical frequency division duplex (FDD) mode OFDMA wireless communication system.

2 is a channel structure of a general time division duplex (hereinafter referred to as "TDD") mode OFDMA wireless communication system.

3 is a transmission and reception timing diagram for initial ranging between a base station and a subscriber station in a typical TDD mode OFDMA wireless communication system.

4 is a transmission and reception timing diagram for initial ranging between a base station and a subscriber station in consideration of the cell radius and the processing delay of the subscriber station of the present invention.

5 shows a typical initial ranging procedure.

6 is a first exemplary view showing an initial ranging subchannel allocation structure of the present invention.

7 is a second exemplary view showing an initial ranging subchannel allocation structure of the present invention.

8 is a third exemplary view showing an initial ranging subchannel allocation structure of the present invention.

9 is a fourth exemplary view showing an initial ranging subchannel allocation structure of the present invention.

10 is a flow chart showing a base station transmission operation of the present invention.

11 is a flowchart showing a base station receiving operation of the present invention.

12 is a flowchart showing a subscriber station transmit / receive operation of the present invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the detailed description of an embodiment of the present invention to be described below, the corresponding SS in the BS can perform the ranging without interference between the ranging signals transmitted in the plurality of SSs in the reception section of the initial ranging response signal of the OFDMA wireless communication system. Let's take a closer look at the devices and methods for doing so. Meanwhile, in the detailed description of the present invention described below, specific details for performing initial ranging between a base station and a subscriber station are used for a more comprehensive understanding of the present invention, but the present invention can be easily made without these specific details and by their modifications. It will be apparent to those skilled in the art that the present invention may be practiced.

First, the BS must broadcast predetermined system parameter information in advance so that all SSs in a cell can perform initial ranging by taking the information when setting up a call. That is, the BS informs the subscriber station in advance of the data signal transmission interval required for data transmission and reception and the initial ranging necessary for performing the initial ranging, and the initial ranging response signal transmitted from the SSs is An initial ranging operation is performed for all SSs that are detected within a ranging reception period configured by a base station and to which a call is to be established with the BS. In this case, the response signal for the band request ranging and maintenance ranging may be detected in a reception section for the initial range, or may be detected by setting a separate reception section.

Accordingly, the BS is required to efficiently set the reception section for detecting the response signals from the SSs. In other words, the ranging of the MAC of the base station is a receiving section for receiving the initial ranging signal so that initial ranging for all the subscriber stations in the base station can be efficiently performed in consideration of the cell radius and the processing delay of the subscriber station. The interval must be set. This will be described in detail with reference to FIG. 4 as follows. 3 is a diagram illustrating transmission and reception timing for initial ranging between a base station and a subscriber station in a typical TDD mode OFDMA wireless communication system, and FIG. 4 is a base station considering a cell radius and processing delay of a subscriber station according to an embodiment of the present invention. Is a diagram illustrating transmission and reception timing for initial ranging between a subscriber station and a subscriber station.

First, the SS uses only two consecutive symbols at a predetermined position to transmit an initial ranging signal for system information transmitted from a BS to perform initial ranging. The BS performs a procedure of detecting a ranging signal with respect to all received symbols when the ranging interval is reached. In this case, an interval corresponding to a cell radius of the BS is added to set a reception interval of the initial ranging signal, that is, a ranging interval length, and a length at which k must be at least not to interfere with the data channel. Perform a ranging detection operation. This will be described in detail as follows.

In general, there are three types of delays in the transmission and reception of data between the BS transmission and the SS, that is, the delay consisting of the propagation delay between the BS and the SS and the processing delay in the BS and the SS itself. The processing delay T ₀ of the BS consists of a transmission delay T ₀₁ of the BS and a reception delay T ₀₂ of the BS, as defined in Equation 1 below.

T ₀ = T ₀₁ + T ₀₂

The processing delay T ₀ of the BS is a constant value constant and known to the BS.

Similarly, the processing delay, T ₂ , of the SS also consists of the transmission delay T ₂₁ of the SS and the reception delay T ₂₂ of the SS, as defined in Equation 2 below.

T ₂ = T ₂₁ + T ₂₂

Again, the processing delay T ₂ of the SS is also a constant constant value, which SS knows.

The propagation delay T ₁ on data transmission is composed of a downlink transmission delay T ₁₁ and an uplink response delay T ₁₂ as defined in Equation 3 below.

T ₁ = T ₁₁ + T ₁₂

The delay time for transmitting and receiving such data is shown in FIG. 3.

After the BS processing delay T ₀ , the SS processing delay T _2, and the propagation delay T ₁ , the MAC of the BS can know the initial time information, T _t1 , at the time D. Therefore, in FIG. 3, which is a general data transmission / reception procedure, initial time information is represented by Equation 4 below.

T _t1 = T ₁₂ + T ₀

Since the processing delay of the BS, T ₀ is a constant and the BS knows this value, T _t1 can be easily obtained from Equation 4 above. However, since BS processing delay, T ₀ has no influence on a time offset set in consideration of ranging interval length and propagation delay, only the processing delay and propagation delay of SS are considered in the present invention.

As shown in FIG. 3, assuming that the BS can predict the time delay T _t2 , T _t2 is the sum of the propagation delay, the processing delay of T ₁ and SS, and T ₂ , as shown in Equation 5 below.

T _t2 = T ₁ + T ₂

At this time, the maximum value of T _t2 , Max_T _t2, is generated when SS has its propagation delay at the cell boundary. That is, this may be expressed as Equation 6 below.

Max_T _t2 = 2R / c + T ₂

Where c is the luminous flux and R is the cell radius.

In order to avoid Inter Channel Interference (ICI) into the data channel due to the initial ranging, when the BS processes the data subchannel, the BS should not receive any initial ranging signal. At this time, the band request range and the maintenance range are in a state in which synchronization for not only transmission power but also time offset is performed by performing initial ranging, and compensation for the propagation delay and processing delay of the SS is performed.

Therefore, if the time required for the initial ranging interval is converted into the number of OFDM symbols used in the MAC of the OFDM system, k, the ranging interval interval length is expressed by Equation 7 below.

Here, T _u is the length of the OFDM symbol including the guard interval, the function cell (x) is a large integer value closest to the element x.

However, the processing delay of each SS may be different depending on the manufacturer, and the BS does not know the processing delay of the SS in the initial ranging period. On the other hand, the SS can know its processing delay. In practice, the processing delay of the SS can be larger than the ranging interval length, k, because OFDM is computationally expensive using the FFT and IFFT procedures. Accordingly, in the present invention, in order to avoid the influence of the processing delay of the SS on the ranging interval length, the SS transmits the ranging signal in advance by its processing time.

In FIG. 4, after the transmission propagation delay and the processing delay of the SS are reflected, the SS may advance the initial ranging signal transmission time by the transmission propagation delay and the processing delay of the SS in advance to transmit at the point A. FIG. At this time, T_AD is equal to T ₂ . Accordingly, Equation 7, which calculates the ranging interval length considering the processing delay of the SS, may be obtained as shown in Equation 8 below.

On the other hand, for a given cell, the BS can know its cell radius after cell planning. Thus, k is a constant for a given cell, and the BS periodically broadcasts ranging related information including ranging intervals so that the ranging related information is transmitted to all subscriber stations in the cell. Accordingly, the SS entering the cell may obtain information necessary for accessing a system such as a ranging interval from ranging related information broadcast from the BS.

Accordingly, when the SS intends to perform initial ranging for establishing a new call with the BS, the BS increases the existing initial ranging signal reception interval by a delay amount corresponding to its cell radius. The SS may receive the ranging subchannel and the ranging code by obtaining ranging intervals, ranging subchannels and ranging code information set for ranging from system information returned from the BS. The SS determines a transmission time point in consideration of its processing delay time, and transmits an initial ranging signal at the determined transmission time point so as to be transmitted earlier than the existing transmission time point. In this case, the initial ranging signal uses a selected random subchannel and a ranging code, which is a response signal corresponding to system information from the BS.

On the other hand, as in the conventional channel structure of the TDD mode OFDMA wireless communication system, a predetermined guard period may be inserted in a carrier period in order to prevent interference generated by using all carriers of a predetermined period as a ranging subchannel. This will be described with reference to FIGS. 6, 7, 8, and 9 as follows.

First, assuming a 2K mode OFDMA wireless communication system having a capacity of 1696 carriers according to the first embodiment, divided into 32 basic data subchannels, that is, B_ch _m as shown in Equation 9 below. The subchannel consists of 53 carriers. Herein, the present invention aims at initial ranging subchannel allocation in a 2K mode OFDMA system and assumes that a DC carrier is not used.

Here, C _mi denotes the i th carrier of the m th basic subchannel.

The 32 basic subchannels, B_ch _m , are divided into three consecutive subchannels, and are composed of 10 ranging subchannels, and the 11th ranging subchannel is configured of two basic subchannels. Therefore, as shown in Equation 10, ranging first to ten ranging subchannels are configured with a total of 159 carriers, and the 11th ranging subchannel is composed of 106 carriers. This ranging subchannel configuration is illustrated in FIG. 6.

In this method, the ranging code is generated by a PRBS (Pseudo Random Binary Sequence) PRBS (hereinafter referred to as PRBS) generator (not shown) described in Section 8.3.5.3.4.3.1 of a predetermined IEEE802.16ab-01 / 01r2. Consists of a code string created by cutting a PN code string into 159 bits long. The 11th ranging subchannel of length 106 uses the first 106 bits of the bit string following 10 ranging codes of 159 bits length.

Since this method uses the carrier allocation method of the existing TDD mode OFDMA wireless communication system as it is, it is compatible with the uplink pilot and data carrier allocation method, and the ranging code also uses the existing PRBS generation code as it is. Since the length of is longer than 159 length or 106 length from the existing 53 bits, it shows better correlation.

Another embodiment of the present invention will be described with reference to FIG. 7. In 2K mode with 180 guard intervals on the left and right side of the ranging subchannel structure, R_ch _m (m = 1, ..., 13) consisting of 128 or 127 adjacent carriers The present invention proposes a ranging subchannel allocation method for providing a guard interval between adjacent ranging subchannels. In this case, the guard interval between the ranging subchannels has two subcarriers when the ranging subchannel is 128 lengths and three subcarriers when the length is 127 lengths.

Therefore, when the ranging subchannel is 127 lengths, only 1687 subcarriers, C _k are used to transmit the ranging signal, and three guard intervals between G _k ranging subchannels are inserted. Each ranging subchannel is configured as shown in Equation 11 below.

The ranging code used here is a gold code and the ranging code length is 127, which is the length of one ranging subchannel. The gold sequence generator is shown in Equation 12 below.

Equation 12 generates 63 gold codes having a length of 127, and has a good balance property and correlation. That is, the number of 63 gold codes is sufficient for initial ranging, and the balance property provides a low PAR.

Referring to FIG. 8 as another embodiment of the present invention, a GCS (Golay Complementary Sequence; GCS, hereinafter referred to as a "GCS") or an M sequence may be used as the ranging code in addition to the gold code. We need a 128-bit ranging subchannel. A 128 length ranging subchannel allocation method using GCS and M sequences is described below.

The 128-length ranging subchannel allocation method is similar to the ranging subchannel allocation method using the gold code as the 127-length ranging code. Since the ranging subchannel is 128 lengths, in 2K mode, 1688 subcarriers can be used to transmit the ranging signal, thus leaving 179 guard intervals on the left and right sides, respectively. The configuration of the ranging subchannel is as shown in Equation 13 below.

An interleaving allocation method as another ranging subchannel structure of the present invention will be described with reference to FIG.

In the 2K mode OFDMA wireless communication system, subcarriers are divided into 26 basic groups, B_ch _m , m = 1, ..., 26, and each basic group is composed of contiguous carriers having 64 lengths, and each of these adjacent basics. There is a guard interval of one subcarrier length between groups. Therefore, since 1689 subcarriers are used for ranging signal transmission, 179 guard intervals are provided on the left and right sides, respectively. Carriers of the basic group and the carrier configuration of the guard interval is shown in Equation (14).

The basic group B_ch _m is combined with two basic blocks in the same manner as block interleaving to form one ranging subchannel. For example, the ranging subchannel, R_ch _m , may be defined as in Equation 15 below.

Here, R_ch _m means the m th ranging subchannel.

In the ranging subchannel allocation methods described above, the initial ranging signal does not affect the data subchannel as the SS performs initial ranging processing in consideration of a cell radius. This is a very important feature when data is transmitted with high-order modulation such as hexadecimal quadrature amplitude modulation (QAM) and 64-QAM. In addition, since there is a guard interval between adjacent ranging subchannels, multiple access interference (hereinafter referred to as " MAI ") due to frequency offset and time offset from different ranging signals can be significantly reduced.

As described above, the BS sets a ranging interval period in consideration of the cell radius, determines the initial ranging subchannel allocation method and the ranging code, and broadcasts it in its cell. The SS acquires information broadcasted by the BS to obtain information necessary for initial ranging, and then transmits a ranging signal to the BS by using a randomly selected ranging subchannel and a ranging code in a ranging interval. When the BS reaches the ranging interval, the BS performs an FFT with the ranging subchannel structure to detect the ranging signal from the SS and performs data subchannel reception outside the ranging interval. The operation of transmitting and receiving the BS will be described in more detail with reference to FIGS. 10 and 11 as follows.

First, as shown in FIG. 10, the BS determines whether system information is transmitted for initial ranging in step 1010, and if the initial ranging information is not transmitted, the BS proceeds to step 1030 to transmit ranging information. Determine if it is required. If the ranging information transmission is not required, the data symbol transmission interval is determined, and in step 1040, the data power is transmitted or received by adjusting the transmission power and time offset currently being controlled. However, if it is determined that the BS transmits system information for initial ranging of the SS to attempt new call setup in its cell in step 1010, the BS proceeds to step 1020. In step 1020, the BS adds the section corresponding to the cell radius of the SS itself to the reception section of the new initial ranging response signal by adding the section corresponding to the cell radius of the SS to all SSs for the transmission of the system information in step 1020. do. When the receiving section is newly set, the BS transmits the system information including the newly set receiving section through a predetermined broadcast channel to be transmitted to all SSs in the BS in step 1050.

In addition, the reception operation of the BS will be described with reference to FIG.

First, in step 1110, the BS checks whether the next reception section is a response signal reception section of the SS for initial ranging or a reception section of general data transmitted from the SS. In step 1110, when the receiving section is identified as the response signal receiving section of the SS for the initial ranging, the BS proceeds to step 1120 to lane the channel structure of the initial ranging receiving section in which the region corresponding to the cell radius is extended. Set to the ranging subchannel structure for the gong. In operation 1130, the controller performs initial ranging by receiving a response signal for the initial ranging received from the SS according to the predetermined ranging subchannel structure. At this time, the BS detects the ranging signal from the ranging subchannel having the FFT, calculates power, and compares the calculated power value with a preset reference value when the ranging interval period is reached. If the received ranging signal power value is larger than the reference value, it is determined that there is no ranging signal in the ranging subchannel, and the above operation is performed on another ranging subchannel, and the received ranging signal power value is If greater than the reference value, the frequency correction operation is performed. In the frequency correction block, the BS detects the ranging code used by the SS by multiplying the received ranging signal by the ranging code of the ranging code set one by one, and then detects the delay time and reports it to a higher layer.

On the other hand, if it is confirmed that the reception period of the general data in step 1110, the process proceeds to step 1140, and the correction is performed not only for the transmission power but also for the time offset. .

The operation of the SS according to the transmission / reception operation of the BS of FIGS. 10 and 11 will be described with reference to FIG. 12 as follows.

First, in step 1210, the SS checks whether it is in a state of newly attempting call setup with the BS or in a state of completing a call setup and transmitting a ranging symbol instead of a current data symbol or initial ranging. If the call is newly attempted in step 1210, the procedure proceeds to step 1220 to determine whether the received symbol is information for ranging or general data information. If the received information is general data, step 1220 is performed again. If the information is necessary for ranging, the SS performs a ranging operation using information necessary for the ranging in step 1250. On the other hand, if it is not a new call setup step in step 1210, the process proceeds to step 1240 and the current transmission and time offset adjustment between the BS and SS is being made, so that the corresponding data is received in a channel structure suitable for data or ranging transmission. Done.

If the ranging signal is received at the SS in step 1230, the SS sets the channel structure for the response signal of the ranging signal received in step 1250, and then proceeds to step 1260 to receive the ranging information. Is for initial ranging or band request ranging or maintenance ranging.

If the system information for initial ranging is received in step 1260, the process proceeds to step 1270. The SS sets a ranging code set as a channel structure for the ranging signal so that a ranging signal can be detected in a BS ranging interval receiving section. And randomly select a ranging subchannel and a code to be used in the ranging subchannel set, and transmit the ranging signal on which the IFFT is performed in advance by the processing delay of the ranging signal. On the other hand, if data related to maintenance ranging or bandwidth request ranging, rather than system information for initial ranging, is received in step 1260, the process proceeds to step 1280 to perform BW response or maintenance ranging and then performs step 1220 again. Perform.

As described above, the ranging interval and ranging subchannel allocation method for initial ranging in the orthogonal frequency division multiple access system according to the present invention is a method for setting an interval interval for initial ranging in consideration of processing delay time of a cell radius and SS in an OFDMA system. The proposed scheme not only prevents interference between signals for initial ranging and signals for data transmission, but also enables efficient operation of resources, which reduces delay and overhead of the physical layer. Has the effect of reducing the head.

In addition, the ranging interval and ranging subchannel allocation method for initial ranging of the present invention orthogonal frequency division multiple access system has an effect of avoiding ICI between guard and data subchannels between ranging subchannels, and There is no need to change the current IEEE802.16ab standard data and pilot subcarrier allocation algorithms for transmission and reception.

Claims (20)

A method of allocating a ranging interval for initial ranging with a subscriber station in a base station of a multi-user orthogonal frequency division multiple access wireless communication system, Determining a reception interval of an initial ranging signal by reflecting a maximum delay expected when transmitting and receiving data with the subscriber station; Broadcasting system information necessary for initial ranging, including the determined reception section, to all subscriber stations in a cell through a predetermined broadcast channel; And receiving an initial ranging signal from the subscriber stations in response to the system information for all symbols received from the subscriber station in the determined reception section. The method as claimed in claim 1, wherein the system information includes a ranging subchannel and a ranging code for the initial ranging. 2. The method as claimed in claim 1, wherein the maximum delay includes a maximum propagation delay between the base station and the subscriber station in consideration of the cell radius. 4. The method of claim 3, wherein the maximum delay comprises a processing delay occurring at the base station. 5. The method of claim 4, wherein the maximum delay comprises a processing delay occurring at the subscriber station. 5. The method as claimed in claim 4, wherein the maximum propagation delay comprises a downlink propagation delay and an uplink propagation delay with the subscriber station in consideration of the cell radius. 6. The method as claimed in claim 5, wherein the maximum propagation delay is proportional to twice the cell radius (R) and inversely proportional to the speed of light (c). 6. The method as claimed in claim 5, wherein the processing delay occurring at the base station includes a processing delay at transmission and a processing delay at reception of the base station. 9. The method of claim 8, wherein the processing delay occurring at the subscriber station comprises a processing delay upon reception and a processing delay upon transmission at the subscriber station. The method as claimed in claim 7, wherein the number k of OFDM symbols corresponding to the maximum delay is determined by Equation 16 below. Where T _u is the length of the OFDM symbol including the guard period, T ₂ is the processing delay occurring at the subscriber station, and ceil (x) represents the largest integer value closest to x. The method as claimed in claim 7, wherein the maximum delay is determined by Equation 17 below. Here, T _u is the length of the OFDM symbol including the guard interval, ceil (x) represents a large integer value closest to x. A method for transmitting ranging signals for initial ranging with a base station by a subscriber station in a wireless communication system of a multi-user orthogonal frequency division multiple access method, Receiving system information necessary for initial ranging including a reception period of the ranging signal from the base station through a predetermined broadcast channel, and determining an arbitrary ranging subchannel and a ranging code from the system information; Adjusting a transmission time of an initial ranging signal in consideration of a processing delay time for initial ranging, and transmitting the initial ranging signal by the ranging subchannel and the ranging code at the adjusted transmission time The method characterized in that. The method of claim 10, wherein the initial ranging signal is transmitted using two consecutive symbols at a predetermined position determined by the ranging subchannel and the ranging code. A method for allocating ranging subchannels and ranging codes for initial ranging with a subscriber station in a base station of a multi-user orthogonal frequency division multiple access wireless communication system, Defining each of the ranging subchannels by dividing a predetermined number of basic subchannels each consisting of a predetermined number of carriers into a predetermined predetermined number; And dividing a successively generated orthogonal code string by the number of carriers corresponding to a predetermined number of basic subchannels constituting the ranging subchannel and assigning the same to the ranging code. The method as claimed in claim 14, wherein the number of carriers constituting the basic subchannel is 53. The method as claimed in claim 14, wherein the basic subchannels are 32. 17. The apparatus of claim 16, wherein each of the first through thirty ranging subchannels of the ranging subchannels comprises three consecutive basic subchannels, each of the thirty first through thirty second ranging subchannels. Said method comprising two consecutive basic subchannels. 18. The apparatus of claim 17, wherein the ranging code corresponding to each of the first to thirtyth ranging subchannels is allocated by cutting the consecutively generated orthogonal code strings by 159 bit length units. And a ranging code corresponding to each of the first ranging subchannels is cut and allocated in units of 106 bits. A method for allocating ranging subchannels and ranging codes for initial ranging with a subscriber station in a base station of a multi-user orthogonal frequency division multiple access wireless communication system, Using 1687 subcarriers to transmit a ranging signal and allocating the ranging subchannel of length 127 having 180 guard intervals on the left and right sides according to Equation 18, The ranging code using the 1687 subcarriers and corresponding to each of the ranging subchannels having the length of 127 includes the step of assigning the ranging code by Equation (19). Here, C _k is a ranging code used to transmit a ranging signal, and G _k represents a ranging code used to insert 3 length guard bands between ranging subchannels. A method for allocating ranging subchannels and ranging codes for initial ranging with a subscriber station in a base station of a multi-user orthogonal frequency division multiple access wireless communication system, 1688 subcarriers are used to transmit a ranging signal, and the ranging subchannel of length 128 having 179 guard intervals on the left and right sides is allocated according to Equation (20).