KR100266540B1 - Reduce method of synchronization time with pilot channel in fhma(frequency hopping/code division multiple-access) system - Google Patents

Abstract

The present invention relates to a method in which a mobile station synchronizes a base station using a control channel including pilot channel information in a frequency hopping / code division multiple access system and shortens an initial synchronization time using a pilot channel when performing a preference function. A first step of setting a plurality of cells of each band frequency for pilot channel frequency allocation between the base station and the mobile station in advance; and the random traffic channel in which the pilot channel frequency is idle for each band except the control band in the base station And a second process of allocating a signal to the mobile station and waiting for reception of a pilot channel in a specific cell of a band of the pilot channel frequency allocation cell preset for each band except for the control band when the mobile station performs initial synchronization. In step 3, pilot channel reception is received in a specific cell of the arbitrary band. A fourth process of skipping a pilot channel frequency for a corresponding cell and preparing to receive a pilot channel frequency for another cell when the mobile station receives the pilot channel; and for each band except the control band in the mobile station And a fifth process of performing the third and fourth processes and a sixth process of performing the preferences in the mobile station performed up to the fifth process.

Description

Reduction of Initial Synchronization Time Using Pilot Channel in Frequency Hopping / Code Division Multiple Access Systems

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system using a frequency hopping / code division multiple access (FHMA) scheme, and more particularly, to a mobile station using a control channel. The present invention relates to a method of reducing initial synchronization time by using a pilot channel when performing synchronization with a base station.

Typically, a basic component of a wireless communication network of a mobile communication system includes a base station (RAU) serving as an entrance and exit of a wired network and a wireless network, and a mobile subscriber station (MST) capable of freely moving in and out of the base station area. There is. In the case of using the FHMA technology in the wireless communication network of the mobile communication system, in order for the mobile station to establish a call with another subscriber, the mobile station must operate in synchronization with each other at the hop frequency (HOP FREQUENCY) promised between the base station and the mobile station. do. The base station is arranged by a cell plan and is based on configuring one unit cell with 16 base stations. Under these circumstances, the base stations are operated at regular intervals and power (POWER), and the base stations and the base stations are configured to overlap each other according to region, topography, or transmission strength.

A connection configuration of a mobile station in an overlapping cell region of a base station is described with reference to FIG.

In a FHMA system, a cell radius of a general base station is 20 km, a basic configuration of 7 cells, and a plurality of overlapping areas between base stations may be provided depending on the terrain. If a mobile station exists in an overlapping area of a plurality of base stations, the best base station may be different according to the location of the mobile station. Here, the highest base station refers to a base station capable of transmitting and receiving a best signal with a mobile station located in an overlapping area. As shown in FIG. 1, the mobile station j is located in a region where the base stations-1, base station-2 and base station-3 overlap, and the mobile station i is the base station-1 and base station as shown in FIG. -2, base station-3 is located in the overlapped area. In FIG. 1, mobile station j is in a position where base station-2 can transmit and receive better signals than base station-1, but is connected to base station-1, and mobile station i can receive signals from all base stations. 3 is the best base station from the RF transmission and reception point, but is connected to base station-2. If it continues to operate in this state, the transmission and reception of the base station as well as the mobile station will not operate under the highest conditions.

That is, the base station is designed so that the effective ranges between the base stations overlap, and the mobile station is a mobile communication terminal that can be subscribed to any base station. You can get it from However, even if it is within the effective range of the base station, the mobile station may be located in an unfavorable position due to the geographical characteristics, and if the subscription is performed without considering the terrain effect at all, the call service may only be performed under such poor conditions. . Therefore, the mobile station located in the overlapping area of the base station performs the preference function when the base station is detected in plural numbers, thereby joining the best base station.

On the other hand, there is a control channel between the base station and the mobile station incorporating both pilot channel and synchronization channel functions. The control channel is a channel capable of simultaneously receiving information as well as synchronization. In order for the mobile station to synchronize with the base station, it is necessary to know the hop pattern (HOP PATTERN) of the base station and the base station can be said that the synchronization of the base station only if the hop synchronization is based on the hop pattern. At the same time, it receives software system information and starts to perform system related operations. Since the mobile station needs to find synchronization for each base station when performing the base station preference function, a huge amount of time is required when receiving the system information. In view of this, if the base station control hop period becomes longer, the initial synchronization time of the mobile station becomes longer. For example, when the base station control period is 8 cycles, the mobile station may be set up rather quickly. If the base station control cycle is 128 cycles, the mobile station may be tuned to each band until the base station control synchronization is received and information is received to perform the comparison between base stations. It will take a lot of time. This will be described in detail with an example.

Comparing the initial synchronization time of the mobile station when the control period of the base station is 16 cycles and 128 cycles;

1. Calculation of T ₁₆ (16 cycles total initial sync time);

T _C16 (16 cycles 1 Cell initial sync time) = 16 (cycles) × 10mSec (TDD Time) × 2 (Tracking Delay Time per Cell) = 320mSec

T _CR16 (16 Cycle 1 Cell RSSI_Rx Initial Sync Time) = 320mSec (T _C16 (16 Cycle 1 Cell Initial Sync Time)) + 250mSec (RSSI Receive Time) = 570mSec

T ₁₆ (16-cycle total initial sync time) = 570 mSec (T _CR16 (16-cycle 1 Cell RSSI_Rx initial sync time)) × 16 (number of cells) = 9120 mSec

2. T ₁₂₈ (128-cycle total initial sync time) calculation;

T _C128 (128 Cycle 1 Cell Initial Synchronization Time) = 128 (cycle) × 10mSec (TDD Time) × 2 (Tracking Delay Time per Cell) = 2560 mSec

T _CR128 (128 Cycle 1 Cell RSSI_Rx Initial Sync Time) = 2560mSec (T _C128 (128 Cycle 1 Cell Initial Sync Time)) + 250mSec (RSSI Receive Time) = 2810 mSec

T ₁₂₈ (128-cycle total initial sync time) = 2810mSec (T _CR128 (128-cycle 1 Cell RSSI_Rx initial sync time)) × 16 (number of cells) = 44960 mSec

Here, the "Tracking Delay Time per Cell" determines whether the mobile station has been tracked by delaying the base station for two periods of hopping in preparation for the mobile station not tracking when the base station is hopping for one cycle. The "RSSI Receive Time" is a Receive Time for receiving an RSSI per Cell in order to perform a preference function.

In addition, Table 1 shows a comparison of the initial synchronization time of the mobile station in the 16- and 128-period base station control periods using 8 and 16 cells.

Mobile Station Initial Synchronization Time Comparison between 16 and 128 Base Station Control Cycles division 16 cycles of control Control 128 cycles 16 Cell 9.12 Sec 44.96 Sec 8 Cell 6.56 Sec 22.48 Sec

During the initial synchronization time, the user must wait until the mobile station is set up, and considering the dead frequency in accepting the dead frequency between the base station and the mobile station, the mobile station has a medium to receive the dead frequency from the base station. It is necessary.

As described above, since the mobile station needs to find synchronization for each base station when performing the base station preference function, it takes a long time to adjust the base station control synchronization of each band and receive system information to perform the comparison between the base stations.

Accordingly, an object of the present invention is to improve the frequency hopping / code division multiple access system in which the mobile station performs a preference function to shorten the synchronization time of the base station even if the control hop pattern period of the base station increases in the FHMA system. The present invention provides a method for reducing initial synchronization time using a pilot channel.

Another object of the present invention is to reduce an initial synchronization time using a pilot channel in a frequency hopping / code division multiple access system that does not require a FILL GUN or a manual to receive available / unusable frequency information from a system. In providing.

In order to achieve the above object, the present invention provides an initial synchronization time using a pilot channel when a mobile station synchronizes a base station using a control channel including pilot channel information in a frequency hopping / code division multiple access system. In the shortening method, the first step of setting a plurality of cells of each band frequency for pilot channel frequency allocation between the base station and the mobile station in advance, and the pilot channel frequency for each band except the control band in the base station A second process of allocating to an idle traffic channel in an idle state; and in a specific cell of any band of the pilot channel frequency allocation cells preset for each band except the control band when performing initial synchronization in the mobile station. A third process of waiting for reception of a pilot channel and a specific cell of the arbitrary band A fourth step of preparing to receive a pilot channel frequency for another cell after skipping a pilot channel frequency for a corresponding cell when the pilot channel is received by the mobile station waiting to receive a pilot channel; and a control band at the mobile station A fifth process of performing the third and fourth processes, and a sixth process of performing the preference in the mobile station performed up to the fifth process for each band except for.

1 is a connection diagram of a mobile station in an overlapping cell of a base station;

Figure 2 is a detailed block diagram of the inside of the base station

3 is a detailed block diagram of the inside of a mobile station;

4A and 4B illustrate pilot channel information of a base station according to the present invention.

5 illustrates base station channel BER information according to the present invention.

6 is a diagram illustrating frequency allocation of a pilot channel according to the present invention.

7 illustrates an example of operating a pilot channel in a base station / mobile station according to an embodiment of the present invention.

8 is a flowchart illustrating an initial synchronization process of a mobile station using a pilot channel according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention, such as specific processing flows. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. Detailed descriptions of well-known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

FIG. 2 is a detailed block diagram of the base station. The base station includes a radio unit 201 and a control unit 203.

The wireless unit 201 is connected to a duplexer 211 for switching according to transmission or reception from the antenna ANT, and receives a tuner 213 for tuning a signal received through the duplexer 211 and demodulates a tuning signal of the tuner 213 to control the control unit. A demodulator 214 for transmitting to 203, an output coupler 212 connected to the duplexer 211 for coupling an output to a transmission output, an output amplifier 215 for amplifying an output signal to be sent out and connected to the output combiner 212, and the control unit 203 A modulator 217 for modulating the output signal and inputting the input signal to the output amplifier 215, and a time distribution duplexer 216 for providing an operation timing signal of the tuner 213, the duplexer 211, and the output amplifier 215 by a control signal generated from the controller 203. do.

In addition, the control unit 203 is a radio wave interference unit 218 to avoid the interference radio waves for the signal to be demodulated and transmitted and received in the modulator / demodulator 214, 217 of the radio unit 201, the central processing unit 222 for controlling the whole of the control unit 203, A trunk interfacing unit 223 for trunk interfacing with a remote base station under the control of the central processing unit 222, a digital subscriber unit 219 for interfacing with a wireless subscriber under the control of the central processing unit 222, and the interference prevention unit 218 A speed rate converter 231 for converting a speed of a transmitted / received signal of the system, a system interface unit 220 connected to the jammer 218 and controlled by the central processor 222 to form a system interface, and a speed controlled by the central processor 222. Switch between digital subscriber unit 219 and trunk interface unit 223 for signals through rate converter 231 It is configured in the switching unit 221 to.

3 is a detailed block diagram of a mobile station;

A duplexer 301 is connected from the antenna ANT, and a low noise amplifier 311 for amplifying a signal received from the duplexer 301, a tuner 313 for tuning to an output of the low noise amplifier 311, and a signal tuned by tuning of the tuner 313 A demodulation unit 315 for demodulation, an electromagnetic wave interference unit (ECCM) 317 for removing radio wave interference with respect to the transmission / reception signal, a modulation unit 305 for modulating an outgoing signal output from the radio wave interference unit 317, and the modulation unit 305 An output amplifier 303 for amplifying the output of the output signal to the duplexer 301, a digital subscriber unit 307 for interfacing a digital subscriber to the transmitted / received data with the jammer 317, a main controller 319 for controlling the entire mobile station, and the main controller. The service controller 309 controls the interfacing with the handset for the voice call under the control of the controller 319.

In order to access and operate a mobile station having the above configuration, a mobile station within a base station can be called only when a mobile station is joined to one base station, and a call with a subscriber of a network can be made through the network. The base station subscription of such a mobile station may be classified into two types according to the situation.

1. Initial subscription

When the mobile station is initially powered by the user, the mobile station receives a parameter for searching for the base station, determines whether the base station exists, and performs a joining procedure with the base station if the base station exists.

2. Move Sign Up

-When a mobile station subscribed to an arbitrary base station moves, the mobile station moves out of the area of the previously subscribed base station and loses synchronization, and when the signal of the previous base station is no longer detected, another base station is searched for another base station. If a signal is detected, the mobile station resynchronizes through the detected control packet and performs a new subscription procedure with the new base station. Here, the fact that the mobile station is connected to the base station refers to a state in which the mobile station is subscribed to the base station.

The base station preference function is required when a plurality of base stations are detected in the two subscription conditions as described above.

An example of information carried on a pilot channel between a base station and a mobile station according to the present invention is shown in Figs. 4a and 4b and the base station channel bit error rate (BER) information according to the present invention. The pilot channel information includes cell number, base station transmission power, SHELF / NET, number of mobile station subscribers subscribed to a base station, base station identification number, bit error rate (BER) number of base station channel, and bit error rate number-specific information. , Frequency correction number, switching station identification number, dead frequency information, and so on.

In addition, the frequency allocation scheme of the pilot channel according to the present invention is shown in FIG. 6, but since there is no overall frequency plan in the present invention, in the present invention, the last 16 bands are divided into base station pilot channel frequencies in each band. . That is, when generating the control / traffic frequency at the base station / mobile station, the last 16 bands divided by the pilot channel frequency are treated as an unused frequency and are not included in the frequency generation.

Looking at pilot channel operation in a base station / mobile station according to the present invention;

The mobile station uses the pilot channel only for preference operation. That is, it is used when synchronization is not found for a certain period of time after initial synchronization search (SEARCH) or synchronization loss (LOST) generation, and during manual operation by a user. In detail, 16 frequencies of the pilot channel are configured based on 16 cells. Depending on the cell number of the base station, the pilot channel of the base station may exist in any band except the control band. According to the channel state of the base station, an idle traffic channel can be allocated as a pilot channel, and after this operation, the channel to which the pilot channel is assigned is allocated as traffic at the end. Then, when another traffic channel is released, it can be assigned as a pilot channel. However, the frequency of the band is fixed. This is a diagram showing an example of the operation of the pilot channel in the base station / mobile station according to an embodiment of the present invention of FIG.

In addition, the base station may perform slow hopping due to a risk that eight frequencies available as pilot channel frequencies are allocated and a pilot channel exists at one frequency. In this case, the hopping may hop the remaining seven bands except for the control band, and may slow hop at an arbitrary time when performing the inter-band hopping. This slow hopping does not have a big problem in performing the preference and can compensate for the weakness of 1 frequency.

In view of this, the mobile station performs a preference. If the pilot channel for cell number 1 is received, the mobile station skips the frequency for the cell number 1 among the pilot channel frequencies and receives the pilot channel frequency for the other cell number. If you prepare, you can reduce your initial synchronization time to a minimum.

Priority of the pilot channel information when performing the preference of the mobile station,

1. Base station operation status (base station self / network connection)

2. RSSI Value (Control Channel Performance)

3. BER vaule (performance of traffic channel) of each channel of base station

4. Number of subscribers subscribed to the base station (probability of receiving service from the base station)

5. The base station transmit power (base station coverage size).

In the pilot channel operation applied to the present invention, other considerations are as follows.

First, when the switching stations overlap each other, it may be impossible to receive packets in the overlapping areas by sharing the pilot channel frequency. In this case, the transmission power levels of the base stations are adjusted so that the switching stations do not overlap or overlap each other. Minimize the area.

Second, when the mobile station scans the pilot channel to perform the preference but none is detected, that is, when all the pilot channels are jammed, the mobile station changes the cell number by referring to the input keycode instead of the pilot channel. Search the control channel of the base station directly. At this time, the mobile station attempts to subscribe to the first base station received without performing the preference function and receives a service.

In addition, when no pilot channel is received at the mobile station, there may be a case where a dead frequency has been received before and a case where never has been received.

In case of receiving the above unused frequency, the control frequency is generated based on the previously unavailable unavailable frequency information, and the control motive is searched. Create and search for control sync.

After performing a search for a predetermined time in this manner, it will be necessary to rescan the pilot channel again.

Third, in a state where the base station control cycle operates at 128 cycles,

When a mobile station searches for a control channel without starting synchronization with a pilot channel or when the mobile station loses synchronization for a while and then searches for a control channel of a base station again, the receiver of the mobile station transmits a packet to another mobile station on an ACCESS channel. (False Alarm) This is because the uplink frequency and the downlink frequency are not separated as in the case of using the frequency as full. In response to this, three types of preamble patterns used by the base station / mobile station are used as follows.

Preamble 1: for base station Tx / for mobile station Rx

Preamble 2: For Hop Update

Preamble 3: for mobile station Tx / for base station Rx

In this way, the preamble pattern for the base station Tx and the preamble pattern for the mobile station Tx are different from each other. The mobile station waits only for preamble 1 and the base station waits for only preamble 3. In this case, when the mobile station directly calls, the calling mobile station switches to preamble 1 when transmitting and transmits the signal.

Fourth, introducing a time hopping concept into the pilot channel;

Here, time hopping is a method for compensating for weakness in ECCM by continuously performing transmission operation at pilot channel 1 frequency, and operates without repeating frequency and periodically repeats transmission / transmission interruption to prevent interference or intentional detection. That's how. For example, if the transmission on / off is repeated in a 100mSec period, the transmission is performed for 100 times each time for 100mSec during 1Sec.

The pilot channel scanning delay time in the time hopping situation,

100mSec Cycle Time Hopping: Maximum Delay 120mSec

; 120 mSec × 16 (16 frequencies per band) × 16 cells = 30.72 Sec

50mSec Cycle Time Hopping: Maximum Delay 70mSec

; 70 mSec × 16 (16 frequencies per band) × 16 cells = 17.8 Sec

No Time Hopping: Maximum Delay 20mSec

; 20 mSec x 16 (16 frequencies per band) x 16 cells = 5.12 Sec. Here, redundancy is assumed to be 2 TDD times.

That is, if time hopping is performed, the time for searching the pilot channel for the above-described time may have to wait for the maximum time depending on the period of time. However, this time may be inconvenient from the user's point of view because it does not operate quickly after initial power-up or after a synchronous loss occurs.

Fifth, introducing the concept of adaptive hopping only for pilot channels;

Here, application hopping detects that someone is jamming the currently transmitting channel, and if it is determined that the jamming state is changed, change the hopping pattern, replace the frequency being jammed with another frequency, or delete the frequency from the hopping pattern. This is how you hop.

Application of application hopping in pilot channel

The concept of a pilot channel in a base station / mobile station system is the concept of "1 frequency base station Tx Only / 1 frequency mobile station Rx Only". From the viewpoint of the base station, since the base station pilot channel has no data to be received and no mobile station transmits, only the value of the reception strength is less than a predetermined level is detected. Using this point, the base station keeps checking the RSSI only for the channel on which the pilot channel is being transmitted. If the RSSI value is below a certain level, the base station keeps the current pilot channel. If the RSSI value is above a certain level, the current pilot channel is jammed. Determine and change the pilot channel to another channel.

The effect on the mobile station reception position is;

Since the mobile station must receive all pilot channel frequencies even if the base station does not use the application hopping method, there is no difference in method and time even in the application hopping situation.

Conditions upon performance;

MDSM currently used in the base station is not to detect the RSSI, but should download the program to detect the RSSI like the mobile station. That is, the base station can read the RSSI value. The effect of this is to compensate for the weakest ECCM capability of the pilot channel.

A preferred embodiment of the present invention will be described in detail with reference to FIG. 8 with reference to the initial synchronization time reduction method using a pilot channel in the above-described FHMA system. In the description of the preferred embodiment of the present invention with reference to FIG. 8, the drawings and descriptions of FIGS. In addition, it should be noted that descriptions already mentioned above that do not require any further explanation are omitted in the following description.

8 is a flowchart illustrating an initial synchronization process of a mobile station using a pilot channel according to an embodiment of the present invention.

In order to use the pilot channel for the synchronization search for performing the mobile station preference according to the present invention, the pilot channel between the base station and the mobile station should be allocated in advance, since it has already been mentioned in the above descriptions of FIGS. The description is omitted here.

The point of time when the mobile station searches for synchronization using a pilot channel is during initial synchronization of the mobile station, when the mobile station fails to hold synchronization for a predetermined time after the synchronization roast, or during manual operation by the user of the mobile station. At this time, the synchronous search of the mobile station as shown in FIG. 8 is performed. This will be described with reference to FIG. 8;

In this case, it is assumed that there are 16 pilot channel frequencies configured based on 16 cells.

In step 801, the mobile station selects an arbitrary band and waits for reception of the pilot channel at cell number 1 to search for synchronization. Then, in step 803, the mobile station checks whether the pilot channel is received in the cell number 1, and proceeds to step 807 when the pilot channel is received in the cell number 1, and proceeds to step 805 if the pilot channel is not received. If a predetermined time has not elapsed, the cell number 1 waits for reception of a pilot channel. If the pilot channel is not received after a certain time elapses, the mobile station proceeds to step 809.

In step 807, the mobile station skips the received pilot channel frequency for the cell number 1 (SKIP) and prepares for reception of the pilot channel frequency for the next cell number.

In step 809, the mobile station checks whether the pilot channel reception operation is completed for each of the entire bands. Perform the steps.

In step 809, if the mobile station determines that the pilot reception operation for the entire band is completed, the mobile station proceeds to step 811 and determines whether at least one pilot channel is received according to the pilot channel reception operation for the entire band. This is to check whether there is at least one skipped pilot channel frequency. If at least one pilot channel exists in step 811, the mobile station proceeds to step 813 to perform a preference using a pilot channel frequency for the cell number of each skipped band.

However, if none of the received pilot channels are received even after the pilot channel reception operation for the entire band is completed in step 811, the mobile station can search the control channel (control synchronization) in the following two ways according to the set program. The first method is to perform the 'a' process, and the second is to perform the 'b' process. In step 'a', the mobile station proceeds to step 831 to check whether the radio frequency has been previously received. If the radio frequency has been received before, proceeds to step 833 and generates a control frequency based on the dead frequency information. In step 835, if the dead frequency has not been previously received, the mobile station determines that all frequencies are available, and generates a control frequency to search for the controlled synchronization. After performing steps 833 and 835, the mobile station checks whether the control synchronous search is performed for a predetermined time or more at the control frequency. In step 837, if the control synchronous search is performed for a predetermined time, the mobile station returns to step 801 to perform subsequent processes sequentially. This re-discovers the sync using the pilot channel.

In step 811, if no pilot channel is received in all bands in step 811, the mobile station proceeds to step 821 in which the mobile station changes the cell number by referring to the input key code without using the pilot channel. In step 823, the mobile station attempts to subscribe to the first received base station without performing a preference. This is because no pilot channel is present in the entire band, meaning that it is being jammed.

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 defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the present invention has an effect of reducing the time required for the mobile station to perform the synchronization function and to synchronize the base station even if the base station control hop pattern period increases.

Another advantage of the present invention is that there is no need for a FILL GUN, MANUAL or any other medium to receive available / unusable frequency information from the system.

Claims (12)

A method for a mobile station to synchronize a base station using a control channel including pilot channel information in a frequency hopping / code division multiple access system and to reduce an initial synchronization time using a pilot channel when performing a preference function, A first step of setting a plurality of cells of each band frequency for pilot channel frequency allocation between the base station and the mobile station in advance; A second step of allocating the pilot channel frequency to an arbitrary traffic channel in an idle state for each band except the control band in the base station; A third process of waiting for reception of a pilot channel in a specific cell of any band among the cells for pilot channel frequency allocation preset for each band except for the control band when the mobile station performs initial synchronization; A fourth step of preparing to receive a pilot channel frequency for another cell after skipping a pilot channel frequency for a corresponding cell when the pilot channel is received at the mobile station waiting to receive a pilot channel in a specific cell of the arbitrary band; , A fifth process of performing the third and fourth processes in each band except for the control band in the mobile station; And a sixth process of performing the preference in the mobile station performed up to the fifth process. The method of claim 1, And a frequency allocated to the pilot channel is treated as an unused frequency. 3. The method of claim 2, wherein the pilot channel information; Cell number, base station transmit power, self / net, number of mobile subscribers subscribed to the base station, base station identification number, base station channel bit error rate number, bit error rate number-specific information, frequency correction number, group identification number, dead frequency information A method of reducing initial synchronization time using a pilot channel in a frequency hopping / code division multiple access system. The method of claim 3, And performing the third to sixth steps if the synchronization is not found for a predetermined time after the base station loses synchronization in the mobile station. The method of claim 3, And performing the third to sixth steps during the manual operation by the user in the mobile station. The method of claim 3, The base station is a method for reducing the initial synchronization time using a pilot channel in the frequency hopping / code division multiple access system, characterized in that the hopping between each band except the control band at a random time when performing the inter-band hopping. The method of claim 1, wherein the mobile station, If none of the pilot channels are received, the method further performs a process of attempting to join a base station initially received by directly searching for a control channel of the base station by changing a band by referring to only an input key code without performing the preference. An initial synchronization time reduction method using a pilot channel in a frequency hopping / code division multiple access system. The method of claim 1, wherein the mobile station, If none of the pilot channels are received, if there is a previously used dead frequency, the control frequency is generated based on the previously received dead frequency information to search for control synchronization. A method of reducing initial synchronization time using a pilot channel in a frequency hopping / code division multiple access system, characterized in that further performing a process of searching for control synchronization by determining and generating a control frequency. 7. The method of claim 6, wherein the priority of pilot channel information when performing a preference of the mobile station is; First, the base station operating state according to the base station self / network connection, Second, the reception strength value of the control channel performance; Third, the performance of the traffic channel according to the band error rate value of each channel of the base station, Fourth, the initial synchronization time reduction method using a pilot channel in the frequency hopping / code division multiple access system characterized in that the base station coverage size. The method of claim 9, And a pilot channel in the base station / mobile station is " 1 frequency base station Tx ONLY / 1 frequency mobile station Rx ONLY ". The method of claim 1, wherein the base station; Receiving strength is checked only for the channel to which the pilot channel is being transmitted. If the receiving intensity value is below a certain level, the current pilot channel is maintained as it is. If the receiving intensity value is above a certain level, the pilot channel is changed to another channel. A method of reducing initial synchronization time using a pilot channel in a frequency hopping / code division multiple access system. The method of claim 1, When the other traffic channel of each band is released in the second step, the channel can be allocated to the pilot channel, characterized in that the initial synchronization time reduction method using a pilot channel in the frequency hopping / code division multiple access system.