KR100270325B1 - Apparatus and method for chip delay acqusition, access message transmission method in mobile station and access message acqusition method in base station - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a chip delay calculation apparatus and a method thereof, and a method for transmitting a connection message and a method for acquiring a connection message using the same.

2. The technical problem to be solved by the invention

The present invention provides an apparatus and method for calculating a chip delay of a mobile terminal for calculating chip delay in a mobile terminal, and a method for transmitting a connection message of a mobile terminal for transmitting an access message in consideration of chip delay and acquiring an access message within an acquisition period. An object of the present invention is to provide a method for acquiring an access message of a base station.

3. Summary of Solution to Invention

The present invention includes a first step in which a mobile terminal extracts information from a signal transmitted from a base station and obtains a chip delay according to the information; A second step of setting a plurality of acquisition sections according to information broadcast from a base station; And a third step of transmitting the access message in consideration of the chip delay such that the access message is located in any one of the set acquisition periods.

4. Important uses of the invention

The present invention is used for fast cell access of a mobile communication system.

Description

Apparatus for calculating chip delay of mobile terminal and method thereof, method of transmitting access message of mobile terminal using same and method of obtaining access message of base station

The present invention relates to a method in which a mobile terminal accesses a base station in order to receive various services from a base station in a code division multiple access (CDMA) wireless communication system, and more particularly, based on a distance from the base station. An apparatus and method for calculating a chip delay of a mobile terminal for transmitting a access message so that the chip delay is located within a predetermined interval and considering only the chip delay within a predetermined interval when the base station receives and demodulates the access message The present invention relates to a method of transmitting a connection message of a terminal and a method of obtaining a connection message of a base station.

A cell access method for receiving various services from a base station in a code division multiple access (CDMA) mobile communication system includes Korean Patent Application No. 94-703125. In this conventional method, the mobile terminal determines the transmission time of the access message based on a system time synchronized with the base station, a slot unit time, and an arbitrary chip delay. The mobile terminal modulates the access message to be sent out through several steps, and in particular, spreads it through a PN sequence (32768 chips in length). The spread modulated access message arrives at the base station with a delay. At this time, the base station acquires the access message sent by the mobile terminal through several demodulation steps.

That is, the base station demodulates the spread-modulated access message through various steps to obtain the outgoing message of the mobile terminal. When the chip rate is 1.2288 Mcps and the base station's service area is 10 km, the chip delay according to the distance of the mobile terminal farthest from the base station is 82 chips at maximum. The arbitrary chip delay is up to 511 chips. Since the base station cannot know how much chip delay should be considered in order to acquire the outgoing message of the mobile terminal, the PN sequence for demodulating the outgoing message is delayed by up to 600 chips per chip. Attempt to obtain the outgoing message. If the total depth (Integral-Depth) of the base station is 2048 chips and only one correlator is used, if the chip delay of the mobile terminal is 82 chips and the arbitrary chip delay is 511 homes, it takes at least 200 ms or more.

In this conventional method, as the chip rate is increased, the chip delay according to the distance of the mobile terminal is gradually increased, and as a result, it takes more time to acquire the outgoing message of the mobile terminal.

In order to solve the above problems, the present invention extracts the distance of the mobile station from the base station in consideration of the transmission power and attenuation of the base station, and transmits a connection message based on the distance. By positioning, the base station can consider only the chip delay within a certain period when receiving and demodulating the access message, which can shorten the acquisition time of the access message of the base station. An object of the present invention is to provide an apparatus for calculating a chip delay of a terminal, a method thereof, and a method of transmitting a connection message of a mobile terminal using the same, and a method of obtaining a connection message of a base station.

That is, the present invention uses the chip delay calculation device and method of the mobile terminal for calculating the chip delay in the mobile terminal based on the outgoing power information, the received power and the calibration value of the base station, and the maximum chip delay and the number of acquisition intervals. It is an object of the present invention to provide a method for transmitting an access message of a mobile terminal transmitting an access message in consideration of a chip delay after setting an acquisition interval and a method for obtaining an access message of a base station obtaining an access message within an acquisition interval.

1 is an exemplary diagram of a service environment of a general mobile communication system.

2 is a diagram illustrating a reference time of a base station and thus a reference time of a mobile terminal.

3 is an explanatory diagram showing chip delay according to a chip rate and a distance between a mobile terminal and a base station.

Figure 4 is a block diagram of an embodiment of a chip delay calculation device of a mobile terminal according to the present invention.

5A and 5B are exemplary diagrams of sending and receiving access messages depending on whether chip delay is considered.

6 is an exemplary diagram of a reference time, an acquisition interval, and a maximum chip delay of a base station.

7 is an exemplary diagram for moving or expanding an acquisition interval.

8 is an exemplary diagram in which a plurality of acquisition sections are set to increase collision avoidance and acquisition probability.

9 is a flowchart illustrating a method for transmitting a connection message of a mobile terminal according to the present invention.

10 is a flowchart illustrating an embodiment of a method for obtaining access message of a base station according to the present invention.

* Explanation of symbols for the main parts of the drawings

11: Mobile Station 12: Base Station

41: broadcast information receiving unit 43: receiving power measuring unit

46: distance calculation unit 48: chip delay calculation unit

A method of transmitting a connection message of the present invention for achieving the above object is a method of transmitting a connection message of a mobile terminal, the first step of the mobile terminal extracts information from the signal transmitted from the base station to obtain a chip delay according to the information; ; A second step of setting a plurality of acquisition sections according to information broadcast from the base station; And a third step of transmitting the access message in consideration of the chip delay so that the access message is located in an arbitrary acquisition period among the set acquisition periods.

In addition, the access message acquisition method of the present invention, the access message acquisition method of the base station, the base station is a first step of acquiring the access message within an arbitrary acquisition interval; A second step of acquiring the access message in the remaining sections when the access message is not obtained in the arbitrary acquisition section; And a third step of checking whether the number of times of acquiring the access message in the remaining intervals is greater than or equal to a predetermined threshold and adjusting the arbitrary acquisition intervals.

In addition, the chip delay calculation apparatus of the present invention, the chip delay calculation apparatus of the mobile terminal, comprising: broadcast information extraction means for extracting the transmission power information and the calibration value of the base station from the broadcast information message of the base station; Reception power measurement means for measuring reception power of a broadcast channel of the base station; Distance obtaining means for obtaining a distance between the mobile terminal and the base station by receiving the output power information and the calibration value from the broadcast information extracting means and the received power from the receiving power measuring means; And chip delay acquiring means for acquiring a chip delay according to the distance between the mobile terminal and the base station.

In addition, the chip delay calculation method of the present invention, the chip delay calculation method applied to the chip delay calculation apparatus of the mobile terminal, the first step of extracting the transmission power information and the calibration value of the base station from the broadcast information message of the base station; A second step of measuring received power of a broadcast channel of the base station; Obtaining a distance between the mobile terminal and the base station according to the extracted transmission power information, the calibration value, and the measured reception power; And a fourth step of acquiring a chip delay according to the acquired distance between the mobile terminal and the base station.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a service environment of a general mobile communication system, and shows that the mobile terminal 11 is separated from the base station 12 by a predetermined distance 13.

FIG. 2 is an exemplary diagram of a reference time of a base station and a reference time of a mobile terminal according to the present invention. Based on FIG. 1, it is shown how many chips the access message sent by the mobile terminal 11 is separated from the reference time of the base station 12. Indicates.

The mobile terminal 11 receives the system synchronization signal from the base station 12 to determine the reference time. The system synchronization signal sent by the base station 12 arrives at a predetermined time delay due to the propagation delay. In consideration of this, the reference time 21 of the mobile terminal 11 is separated from the reference time 22 of the base station 12 by the chip delay 23 by the distance between the base station and the mobile terminal.

If the mobile terminal 11 transmits the access message at the reference time 24, when the propagation delay of the access message is considered, the base station 12 receives the access message at the time 25 when the access message is received. Since the access message received by the base station 11 is eventually separated by the chip delay 26 of the access message by the distance between the mobile terminal and the base station from the reference time 22 of the base station 12, the base station 12 The signal is demodulated with a delay of one chip in consideration of the chip delay 26 of the access message based on the reference time 22. The chip delay can be calculated by Equation 1 below based on the chip rate and the distance between the mobile terminal and the base station.

Chip delay = chip rate x ((distance between mobile terminal and base station x 2) / propagation speed)

For example, if the chip rate is 1.2288 Mcps and the distance between the mobile terminal and the base station is 10 km, the chip delay is 82 chips (= 1.2288e6 x ((10 x 2) / 3e5)).

3 is an explanatory diagram showing chip delay according to the distance and the chip rate between the mobile terminal and the base station, and as the distance and the chip rate between the mobile terminal and the base station increase according to Equation 1, the chip delay increases significantly. Shows.

In the figure, the lower line 31 shows a case where the chip rate is 1.2288 Mcps, the middle line 32 shows a case where the chip rate is 4.096 Mcps, and the upper line 33 shows a case where the chip rate is 8.192 Mcps. As the distance between the mobile terminal and the base station and the chip rate increase, the chip delay increases, and thus, the base station takes more time to acquire the access message of the mobile terminal. If the mobile terminal obtains the expected chip delay based on the distance from the base station before sending the access message, and sends the access message based on the distance, the base station considers only the chip delay within a certain interval and accesses the mobile terminal in a shorter time. The message can be obtained.

In general, the distance between a mobile terminal and a base station in a mobile communication environment can be obtained as shown in Equation 2 below. The unit of transmission power and reception power of the base station is decibel (dB).

Distance between mobile terminal and base station = (base station transmit power / (attenuation constant x base station receive power)) ^1/4

The attenuation constant of Equation 2 is a constant value determined by the transmission frequency as shown in Equation 3 below. Transmission frequency is in megahertz (MHz), and propagation speed is in kilometers (Km).

Attenuation Constant = (4 x π x Transmission Frequency) / Propagation Speed

The result obtained through Equation 2 is less accurate in the urban area with many buildings. This phenomenon is called an error due to multipath fading, and the error can be prevented to some extent by adding a correction value to Equation 2 as shown in Equation 4 below.

Distance between mobile terminal and base station = (base station transmit power / (attenuation constant x base station receive power)) ^1/4

± correction by multipath fading

By correcting the error due to multipath fading as shown in Equation 4, the mobile terminal can obtain a distance from the base station.

4 is a block diagram of an embodiment of a chip delay calculation apparatus of a mobile terminal according to the present invention.

First, in order to obtain the transmission power of the base station, the broadcast information receiver 41 extracts the transmission power information 42 of the base station from the broadcast information message of the base station. The transmission power information 42 of the base station refers to the transmission power of the broadcast channel. Next, in order to obtain the reception power of the base station, the reception power measurement unit 43 measures the reception power 44 of the broadcast channel. In order to obtain an error correction value due to multipath fading, the broadcast information receiver 41 extracts the correction value 45 from the broadcast information message of the base station.

The distance calculator 46 calculates the distance 47 between the mobile terminal and the base station by using the transmission power information 42 of the base station, the received power 44 of the broadcast channel, and the correction value 45 as inputs to the distance calculation algorithm. .

The chip delay calculator 48 substitutes the distance 47 between the mobile terminal and the base station in Equation 1 to obtain the chip delay 49 expected when the mobile terminal sends the access message.

5A and 5B are exemplary diagrams of transmitting and receiving access messages according to whether chip delay is considered or not, and when the chip delay is not considered and the chip delay is considered, respectively, the access message transmission time of the mobile terminal and the access by the base station are shown. Shows message reception time.

In the case where the chip delay is not considered, the base station receives the access message of the mobile terminal by a delay of the chip delay 51 of the access message rather than the reference time of the base station. When the mobile station transmits the access message more quickly based on the chip delay 52, the base station receives the access message of the mobile station near the base station reference time.

In consideration of the chip delay, when the error correction value due to the multipath fading is not correct, the access message sent by the mobile terminal may be received earlier than the reference time of the base station. Since the demodulation may not be possible due to collision with other access messages when the transmission time is slightly earlier than the reference time of the base station, the mobile terminal transmits the data slightly later than the chip delay 52 obtained through the chip delay calculation unit 48. .

6 illustrates an example of a reference time, an acquisition interval, and a maximum chip delay of a base station. The access message 61 transmitted by the mobile terminal based on the chip delay 52 obtained through the chip delay calculation unit 48 is a base station. Since the base station is located within a predetermined section 63 of the reference time and the maximum chip delay time 62, the base station searches only a predetermined section 63 of the base station reference time so that the access message of the mobile terminal can be obtained more quickly. It is displayed.

The predetermined interval 63 determined by the base station to acquire the access message is called an acquisition interval. The width of the acquisition section in FIG. 6 is determined by the accuracy of the chip delay calculator 48 or the acquisition result of the base station. The accuracy of the chip delay calculator 48 is generated by multipath fading, which in turn is determined by the accuracy of the error correction value due to multipath fading. In this way, all mobile terminals use the chip delay calculator 48 to transmit the access message so that the access message is located within a predetermined period of the base station reference time regardless of the distance from the device station.

FIG. 7 illustrates an example of a movement or extension of an acquisition interval, when the base station fails to acquire an access message of the mobile terminal because the access message 71 of the mobile terminal is not located in the acquisition period 72 of the base station reference time. , By retrieving the remaining section 73 other than the acquisition section, the possibility of obtaining a mobile terminal access message can be increased.

Here, the remaining section 73 refers to a section excluding the acquisition section 72 among the maximum chip delay time from the base station reference time. When the base station does not acquire the access message by searching the acquisition section 72 and frequently acquires the access message through the remaining sections 73, the base station moves the acquisition section to a section having a high success rate to increase the probability of obtaining the access message. (74) The width can be widened (75).

On the other hand, when all mobile terminals transmit the access message using only one acquisition interval, the possibility of collision increases. To prevent this, the base station broadcasts the number of acquisition intervals and the maximum chip delay through broadcast information, and the mobile terminal sets several acquisition intervals by using them (sets the same as the base station), and randomly among them. By selecting a section and sending a connection message, the possibility of collision can be reduced. The mobile terminal and the base station are equally divided between the base station reference time of the acquisition interval and the maximum chip delay by using Equation 5 below.

Spacing between acquisition intervals = maximum chip delay / (number of acquisition intervals + 1)

According to Equation 5, the interval between the acquisition intervals is greater than or equal to a predetermined value according to the maximum chip delay value and the number of acquisition intervals, thereby increasing the success probability of acquiring the access message.

8 is an exemplary diagram in which a plurality of acquisition sections are set in order to increase collision avoidance and acquisition probability, and show an example in which two acquisition sections are set within a maximum chip delay value and a connection message is transmitted based thereon.

The mobile terminal located in the service area of the base station obtains two acquisition periods 82 and 83 using the number of acquisition intervals broadcast from the base station and the maximum chip delay value 81. Any one of the acquisition periods 82 and 83 of the mobile terminal is selected to transmit an access message (84 and 85).

If the base station simultaneously or sequentially retrieves the acquisition period (82, 83) to obtain the access message (84, 85), and if the acquisition message (84, 85) through the acquisition period (82, 83), Search for remaining sections other than each acquisition section to obtain an access message. In addition, since the access message sent by the mobile terminal through each acquisition section 82 and 83 is separated by a predetermined interval 86 between the acquisition sections, the possibility of acquiring the access message becomes higher.

9 is a flowchart illustrating a method of transmitting a connection message of a mobile terminal according to the present invention.

First, the mobile terminal receives the transmission power information, the reception power, and the calibration value of the base station, and calculates a chip delay based on the transmission power information (91). Thereafter, a plurality of acquisition sections are set using the maximum chip delay and the number of acquisition sections (92).

Thereafter, the mobile terminal transmits the access message in consideration of the chip delay so that the access message reaches the base station in any acquisition period of the acquisition period (93). Then, since the access message is located in the acquisition interval, the base station first acquires the access message in the acquisition interval, thereby shortening the access message acquisition time. If there is no access message in the acquisition section, the base station acquires the access message in the remaining sections.

10 is a flowchart illustrating a method for obtaining access message of a base station according to the present invention.

First, when the access message is received from the mobile terminal (101), the base station acquires the access message within the acquisition interval (102). In this case, when the access message is acquired in the access section, the access message is repeatedly performed from the process of receiving the access message 101. If the access message is not obtained in the acquisition section, the access message is obtained in the remaining sections (103).

Thereafter, after increasing the count value (the number of times a connection message is obtained in the remaining interval) by " 1 " (104), it is determined whether the count value is greater than or equal to a predetermined threshold (which can be arbitrarily determined by the implementor) (105). If it is small, the access message may be repeatedly performed from the process of receiving the message 101, and if it is greater than or equal to the threshold value, the acquisition time may be shortened by moving the acquisition interval or expanding the acquisition interval 106.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary knowledge.

As described above, the present invention extracts the distance of the mobile station from the base station in consideration of the transmission power and attenuation of the base station, and transmits a connection message based on the distance so that the chip delay is located within a predetermined period. When receiving and demodulating the access message, only a chip delay within a predetermined period can be taken into account, thereby reducing the access message acquisition time of the base station. The access message can be distributed by placing several such intervals. There is an effect that can increase the probability of acquisition.

Claims (12)

In the method of transmitting a connection message of a mobile terminal, A first step of the mobile terminal extracting information from a signal transmitted from a base station and obtaining a chip delay according to the information; A second step of setting a plurality of acquisition sections according to information broadcast from the base station; And A third step of transmitting the access message in consideration of the chip delay so that the access message is located in an arbitrary acquisition period among the set acquisition periods; Method of transmitting a connection message of a mobile terminal comprising a. The method of claim 1, The information extracted from the signal transmitted from the base station of the first step, A method for transmitting a connection message of a mobile terminal, including transmission power information, reception power, and a calibration value. The method of claim 2, The transmission power information, And the base station periodically broadcasts its own transmission power information through a broadcast channel. The method of claim 3, wherein The correction value is, And the base station periodically broadcasts a correction value through a broadcast channel. The method according to any one of claims 1 to 4, The broadcast information of the second stage, A method for transmitting an access message of a mobile terminal including a maximum chip delay and a number of acquisition intervals. The method of claim 5, Obtaining the chip delay of the first step, A method of transmitting a connection message of a mobile terminal, characterized by calibrating chip delay by applying an error correction value due to multipath fading. The method of claim 6, The process of setting a plurality of acquisition sections of the second step, A method of transmitting an access message of a mobile terminal, characterized in that a plurality of acquisition intervals are set at regular intervals by dividing equally between the base station reference time and the maximum chip delay. In the method of obtaining an access message of a base station, The base station obtaining a connection message within an arbitrary acquisition period; A second step of acquiring the access message in the remaining sections when the access message is not obtained in the arbitrary acquisition section; And A third step of checking whether the number of times of acquiring an access message in the remaining interval is greater than or equal to a predetermined threshold and adjusting the arbitrary acquisition interval; Method of obtaining a connection message of the base station comprising a. The method of claim 8, The obtaining step adjustment process of the third step, And obtaining the access message of the base station. The method of claim 8, The obtaining step adjustment process of the third step, And a method of acquiring the access message of the base station, wherein the arbitrary acquisition interval is widened. In the chip delay calculation device of a mobile terminal, Broadcast information extracting means for extracting transmission power information and a calibration value of the base station from the broadcast information message of the base station; Reception power measurement means for measuring reception power of a broadcast channel of the base station; Distance obtaining means for obtaining a distance between the mobile terminal and the base station by receiving the output power information and the calibration value from the broadcast information extracting means and the received power from the receiving power measuring means; And Chip delay obtaining means for obtaining a chip delay in accordance with a distance between the mobile terminal and the base station Chip delay calculation device of the mobile terminal made, including. In the chip delay calculation method applied to the chip delay calculation device of a mobile terminal, Extracting transmission power information and a calibration value of the base station from the broadcast information message of the base station; A second step of measuring received power of a broadcast channel of the base station; Obtaining a distance between the mobile terminal and the base station according to the extracted transmission power information, the calibration value, and the measured reception power; And A fourth step of acquiring a chip delay according to the acquired distance between the mobile terminal and the base station Chip delay calculation method comprising a.