KR101022097B1 - Synchronous acquisition method in mobile communication system - Google Patents

Synchronous acquisition method in mobile communication system Download PDF

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KR101022097B1
KR101022097B1 KR20030046155A KR20030046155A KR101022097B1 KR 101022097 B1 KR101022097 B1 KR 101022097B1 KR 20030046155 A KR20030046155 A KR 20030046155A KR 20030046155 A KR20030046155 A KR 20030046155A KR 101022097 B1 KR101022097 B1 KR 101022097B1
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preamble
group
base station
terminal
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KR20030046155A
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Korean (ko)
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KR20050007479A (en
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원승환
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엘지전자 주식회사
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Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system for acquiring initial synchronization by transmitting a preamble in a slot unit from a transmitter to a receiver. More particularly, the present invention relates to a synchronization acquisition method of allocating at least two preambles to consecutive access slots. The synchronization acquisition method according to the present invention comprises the steps of grouping preambles to be transmitted; Allocating transmit power to a preamble group and transmitting the transmit power to a base station; Detecting the preamble from the preamble group to ensure uplink synchronization, and transmitting a synchronization acquisition indicator to the terminal.
Initial Sync, Preamble, Transmit Power, Access Slot

Description

Synchronization Acquisition Method in Mobile Communication System {SYNCHRONOUS ACQUISITION METHOD IN MOBILE COMMUNICATION SYSTEM}

1 is a diagram illustrating a preamble and a synchronization acquisition indicator transmitted between a terminal and a base station for initial synchronization of uplink and downlink.

2 is a diagram illustrating random processing transmission of a preamble for synchronization acquisition.

3 is a diagram illustrating a procedure for increasing transmission power of a preamble during random transmission.

4 is a diagram illustrating a structure of a random processing slot of a preamble transmitted from a terminal.

5 is a diagram illustrating timing of a preamble and a synchronization acquisition indicator.

6 is a diagram illustrating a preamble transmission and a power increase rule in a synchronization acquisition method according to the present invention.

7 is a diagram briefly showing a synchronization acquisition method according to the present invention.

8 is a diagram illustrating a transmission timing of a synchronization acquisition indicator in the synchronization acquisition method according to the present invention.

******* Description of the symbols for the main parts of the drawing ********

P: preamble AI: acquisition indicator

RACH: Random Access Channel AICH: Acquisition Indicator Channel

M: Message

The present invention relates to the initial synchronization of the CDMA mobile communication system, and more particularly, to a synchronization acquisition method of a mobile communication system that can reduce the uplink acquisition time.

In the 3GPP WCDMA wireless communication system, a radio resource control (RRC) state is defined to distinguish an operation mode and a communication state of a terminal. The RRC state is largely divided into an idle mode and a connected mode. When the RRC connection is established between the UE and the UTRAN, the UE transitions from the idle mode to the connected mode.

The access mode is classified into a cell dedicated channel (CELL_DCH), a cell forward access channel (CELL_FACH), a cell paging channel (CACH_PCH), and a URA paging channel (URA_PCH) according to the type of physical channel available to the terminal.

CELL_DCH is a state in which a dedicated channel (DCH) necessary for continuous data transmission is allocated, and CELL_FACH is a state for monitoring a forward access channel (FACH). The UE monitors all FACHs transmitted to the UE in the CELL FACH mode. CELL_PCH and URA_PCH are monitoring the paging channel (PCH). At this time, the CELL_PCH or URA_PCH is classified according to whether to update the cell or URA.

Therefore, in order to transmit data, a switch from CELL_FACH to CELL_DCH is required. However, in order to transmit data by switching from CELL_FACH to CELL_DCH, that is, to configure one dedicated channel (DCH), uplink and downlink synchronization between the terminal and the base station should be performed.

1 is a diagram illustrating signal transmission between a terminal and a base station for uplink and downlink synchronization.

As shown in FIG. 1, for uplink synchronization, a UE transmits a preamble (hereinafter, referred to as a RACH preamble) to a base station through a random access channel (RACH), and the base station receiving the preamble transmits uplink synchronization. The synchronization acquisition indicator, indicating that the SCC has been acquired, is transmitted to the UE through an AQUI. Accordingly, the terminal receives an indicator transmitted from the base station (hereinafter referred to as an AICH indicator) to obtain downlink synchronization. Here, the AICH indicator is transmitted by the AICH transmitter of the base station.

Hereinafter, the uplink synchronization acquisition method will be described in more detail.

First, the terminal initializes the transmit power of the RACH preamble (hereinafter referred to as P) with an appropriate power, and then transmits a 4096 chip RACH preamble to the base station.

In this case, as shown in FIG. 2, the UE retransmits the RACH preamble P by a predetermined maximum number of transmissions until the AICH indicator is received from the base station. In addition, the transmission power of the retransmitted RACH preamble (P) is increased by Δ value, as shown in FIG. Where? Represents the power increase between the preambles, T represents the processing time, and Tn represents the random delay time.

Then, when the AICH indicator is received from the base station in response to the RACH preamble (P), the terminal transmits a message (data) of 10ms or 20ms to the base station through the dedicated channel. Here, Tm denotes a message transmission interval, and Ta denotes a transmission interval of the AICH indicator.

4 is an example of a random slot structure for transmitting a RACH preamble.

As shown in FIG. 4, the RACH preamble is allocated to one access slot consisting of two slots. Each terminal allocates a RACH preamble to an access slot and transmits to the base station at the beginning of each slot. In this case, for example, a slotted ALOHA technique may be used to transmit the RACH preamble.

5 is a diagram illustrating transmission timing of an RACH preamble and an AICH indicator.

As shown in FIG. 5, the terminal transmits the RACH preamble P to the base station every three or four access slots according to a predetermined rule. When the AICH indicator (AI) is received from the base station after a predetermined time elapses, the terminal starts sending a message to the base station. Here, t pp is the distance between the preamble (P), t pa is the distance between the preamble and the synchronization acquisition indicator (AI), t pm is the distance between the preamble and the message.

As described above, in the 3GPP WCDMA wireless communication system, the terminal transmits a preamble at predetermined intervals to acquire initial synchronization of uplink. However, in the related art, since one preamble is transmitted every three or four access slots, there is a problem in that an average reception time of the preamble is long at the receiving end and the detection probability is low. This problem may be further exacerbated when signal detection is not successful with only the first preamble.                         

As a result, the uplink synchronization acquisition at the base station is delayed due to an increase in the average reception time of the preamble, and the bursty data transmission / reception process is delayed due to the delay in the uplink synchronization acquisition, thereby increasing the average reception time of the preamble. Results in reducing the performance of the overall mobile communication system.

An object of the present invention is to provide a synchronization acquisition method in a mobile communication system that can reduce the synchronization acquisition time of the uplink.

Another object of the present invention is to provide a synchronization acquisition method in a mobile communication system that can increase the detection probability of a preamble at a receiving end.

Another object of the present invention is to provide a synchronization acquisition method in a mobile communication system that can obtain diversity gain during preamble transmission.

Synchronous acquisition method of a mobile communication system according to the present invention to achieve the above object,
In the synchronization acquisition method of the mobile communication system for obtaining the initial synchronization by transmitting a preamble of the slot unit from the terminal to the base station,
(A) at the terminal, allocating a first preamble group to consecutive first access slots and second access slots, wherein the first preamble group is a first-first preamble and a first-second preamble. Including the emblem,
The first-first preamble of the first preamble group is allocated to the first access slot, and the 1-2 preamble of the first preamble group is allocated to the second access slot, and the first The -2 preamble has a transmission power greater than the 1-1 preamble by a first increment (Δ);
(B) transmitting the first preamble group allocated to the first access slot and the second access slot to the base station;
(C) checking whether a synchronization acquisition indicator has been received from a receiver for a predetermined time after the terminal transmits the first preamble group;
(D) if the terminal does not receive the synchronization acquisition indicator during the predetermined time, checking whether the number of transmissions of the preamble group reaches a preset maximum transmission number;
(E) when the number of transmissions is less than the maximum number of transmissions, the terminal assigning a second preamble group to consecutive third access slots and fourth access slots, and transmitting the second preamble group to the receiver; It is done.
In addition, in the mobile communication system for transmitting the preamble of the slot unit from the transmitter to the receiver to achieve the initial synchronization in order to achieve the above object, the synchronization acquisition method according to the present invention in the transmitter, the preamble in a continuous access slot Assigning; And transmitting the allocated preamble to the receiver.

Preferably, the access slot is characterized in that at least two or more.

Preferably, the transmission power between the consecutive preambles is set to be different by a predetermined value.

Preferably, the transmission power between the consecutive preamble transmissions is set to be different by a predetermined value.                         

Preferably, the transmitter is a terminal, the receiver is characterized in that the base station.

The synchronization acquisition method further includes detecting a transmitted preamble and transmitting a synchronization acquisition indicator from a receiver to a transmitter.

Preferably, when the receiver successfully detects the first preamble, the receiver transmits a synchronization acquisition indicator regardless of whether the second preamble is received.

Preferably, the receiver adds N preambles to detect the preambles if the N-1 preambles are not successfully detected.

Preferably, the receiver detects the preamble by adding the first preamble and the second preamble if the first preamble is not successfully detected.

Preferably, the transmission period of the continuous preamble is characterized in that it is adjusted according to the traffic amount of the receiver.

In order to achieve the above object, a mobile communication system for acquiring initial synchronization by transmitting a preamble of a slot unit from a transmitter to a receiver comprises the steps of: grouping preambles to be transmitted; Allocating transmit power to a preamble group and transmitting the transmit power to a base station; Detecting the preamble from the preamble group to obtain uplink synchronization, and transmits a synchronization acquisition indicator to the terminal.

Preferably, the preamble is assigned to a group of consecutive access slots.

 Preferably, the number of preambles grouped is at least two.

Preferably, the transmission power between preambles in the preamble group is set to be different by a predetermined value.

Preferably, the transmission power between the preamble groups is set to be different by a predetermined value.

Preferably, when the base station successfully detects the first preamble, the base station transmits a synchronization acquisition indicator regardless of whether the second preamble is received.

Preferably, when the base station does not successfully detect the first preamble, the base station detects the preamble by adding the first preamble and the second preamble.

Preferably, the base station detects the preamble by adding the N preambles if the base station does not successfully add the N-1 preambles.

Preferably, the transmission period of the preamble group is adjusted according to the traffic amount of the base station.

Preferably, the preamble is transmitted through a Random Access Channel (RACH), and the synchronization acquisition indicator is transmitted through an Acquisition Indication Channel (AICH).

Hereinafter will be described a preferred embodiment of the present invention.

The present invention proposes a method for reducing uplink synchronization acquisition time by detecting a preamble faster in a base station.

To this end, the present invention groups and transmits a preamble transmitted from the terminal. That is, the preamble is transmitted over consecutive access slots. The preamble is allocated to each access slot, and the number of preambles grouped is at least two or more.

The present invention defines the power between preamble groups and the power between preambles allocated to each preamble group. The transmission power between the preamble groups and the transmission power between the preambles in each preamble group may be increased to the same width or different widths. For example, as the transmission power increment between between preamble group and preamble as both set to DELTA, or, shown in Figure 6, the transmission power increment between preamble group and set to DELTA *, the transmission power increment between the preamble is set to DELTA Can be. Preferably, ㅿ * is greater than or equal to ㅿ. In this case, the transmission power of a first preamble of the second pre-imbeul group is the same as the transmission power of the second preamble of the first preamble group or will be set larger by DELTA *.

In addition, the transmission period of the preamble group is adjusted according to the probability of collision with the preambles transmitted by each terminal, for example, the amount of traffic at the base station.

The method will improve the preamble detection probability at the receiver due to the time diversity gain, thereby obtaining a better average sync acquisition time. In this case, the transmitter is a terminal and the receiver is a base station.

As described above, since the preamble group transmitted by the transmitter includes at least two preambles, uplink synchronization acquisition time is influenced according to which rule the receiver detects the preamble. Accordingly, the present invention proposes a method for detecting a preamble in a receiver.                     

For example, if the preamble detection is successful using only the first preamble (or signal) of the preamble group, the receiver immediately transmits a synchronization acquisition indicator to the transmitter regardless of whether the second preamble is received. In another embodiment, the preamble detection is successful using only the first preamble. If not, the receiver receives the second preamble and then performs signal detection using a post-detection integration technique. After receiving the N-1 preambles in the same manner and then successfully detecting the signal using the post-detection integrator method, the N-th preamble is received and then the signal is detected using the post-detection integrator method.

The post-detection integration is a technique used in a non-coherent reception method that receives a signal using only energy level without using phase information. The post-detection integration uses a time diversity to improve a signal detection probability. Height is a technique. When the receiver detects a signal on the time axis, the receiver temporarily stores the first preamble received in a buffer, and then sequentially adds the received preamble with the stored preamble to determine whether the preamble is detected.

Hereinafter, the uplink synchronization acquisition method according to the present invention will be described.

7 is an uplink synchronization acquisition method according to the present invention.

As shown in FIG. 7, the terminal groups two preambles P to be transmitted (S10). That is, two preambles P are allocated to consecutive uplink access slots.

When the preambles are grouped, as shown in FIG. 6, the terminal allocates transmission powers of the preamble group and the two preambles constituting the preambles, and transmits them to the base station (S11) and (S12). The preamble is transmitted on the RACH. In this case, as shown in FIG. 6, the transmit power of the second preamble P of the preamble group is set to be higher than the transmit power of the first preamble P.

The base station receives the preamble group and acquires uplink synchronization, and then allocates a synchronization acquisition indicator (AI) to the downlink access slot and transmits it to the terminal. At this time, the AI is transmitted through the AICH, the AI transmission timing for the preamble groups transmitted from each terminal is shown in FIG.

After transmitting the preamble group, the terminal checks whether a synchronization acquisition indicator (AI) has been received from the base station for a predetermined time (S13). As a result of the check, when the AI is received, the terminal acquires the downlink and then transmits a message (M) to the base station (S14). If the AI is not received, the terminal checks whether the maximum number of transmissions is reached. If the number of transmissions is less than the maximum number of transmissions, the terminal repeatedly performs the operation after step S10.

At this time, the transmit power of the second preamble group is set higher by ㅿ * than the transmit power of the first preamble group, as shown in FIG. That is, the transmit power of the first preamble (P) of the second preamble group is set by 높게 * higher than the transmit power of the second preamble (P) of the first preamble group, and the transmit power of the second preamble (P) of the second preamble group is the first. The transmission power of the preamble P is set to be higher by ㅿ.

As described above, the present invention has the effect of reducing the acquisition time of uplink synchronization by shortening the acquisition time by grouping and transmitting the preambles used for acquiring uplink synchronization, and shortening the call establishment time between the terminal and the base station. have.

In addition, the present invention increases the preamble detection probability at the base station by transmitting the preamble by setting two consecutive access slots and can reduce the throughput loss due to the conventional preamble detection delay. That is, it is possible to derive an increased uplink capacity.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (20)

  1. In the synchronization acquisition method of the mobile communication system for obtaining the initial synchronization by transmitting a preamble of the slot unit from the terminal to the base station,
    (A) at the terminal, allocating a first preamble group to consecutive first access slots and second access slots, wherein the first preamble group is a first-first preamble and a first-second preamble. Including the emblem,
    The first-first preamble of the first preamble group is allocated to the first access slot, and the 1-2 preamble of the first preamble group is allocated to the second access slot, and the first The -2 preamble has a transmission power greater than the 1-1 preamble by a first increment (Δ);
    (B) transmitting the first preamble group allocated to the first access slot and the second access slot to the base station;
    (C) checking whether a synchronization acquisition indicator has been received from a receiver for a predetermined time after the terminal transmits the first preamble group;
    (D) if the terminal does not receive the synchronization acquisition indicator during the predetermined time, checking whether the number of transmissions of the preamble group reaches a preset maximum transmission number;
    (E) when the number of transmissions is less than the maximum number of transmissions, the terminal assigning a second preamble group to consecutive third access slots and fourth access slots, and transmitting the second preamble group to the receiver; A synchronization acquisition method of a mobile communication system.
  2. The transmit power of the second preamble group is:
    And a second increment (△ * ) greater than the transmit power of the first preamble group.
  3. The method of claim 1, wherein in the step (E), the second preamble group,
    A 2-1 preamble and a 2-2 preamble,
    The 2-1 preamble is allocated to the third access slot, the second-2 preamble of the second preamble group is allocated to the fourth access slot, and the second-2 preamble is the second preamble. 2-1. The synchronous acquisition method of the mobile communication system, characterized in that the transmission power is larger by a first increment (△) than the preamble.
  4. The method of claim 1, wherein in the step (C)
    When the base station detects the preamble of the first preamble group received,
    And receiving, by the terminal, a synchronization acquisition indicator transmitted by the base station.
  5. The method of claim 4, wherein the base station
    And upon successful detection of the first-first preamble of the first preamble, transmitting a synchronization acquisition indicator regardless of whether the 1-2 preamble is received.
  6. The method of claim 4, wherein the base station
    And if the first-first preamble is not successfully detected, the preamble is detected by adding the first-first preamble and the one-two preamble to detect the preamble.
  7. The method of claim 4, wherein the base station
    And if N-1 preambles are not successfully detected, adding the N preambles to detect the preambles.
  8. The method of claim 1, wherein the transmission periods of successive preambles in the first and second preamble groups are adjusted according to the traffic amount of the receiver.
  9. 2. The preamble of claim 1 wherein the preambles in the first and second preamble groups are:
    Transmitted through a random access channel (RACH),
    The motivation acquisition indicator
    A synchronization acquisition method of a mobile communication system, characterized in that transmitted through the acquisition indication channel (AICH).
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CN101578783A (en) * 2007-01-10 2009-11-11 Lg电子株式会社 Method for constructing data format in mobile communication and terminal thereof

Citations (3)

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Publication number Priority date Publication date Assignee Title
KR20000014424A (en) * 1998-08-17 2000-03-15 윤종용 Apparatus and method for transmitting preamble of access channel
KR20020064575A (en) * 2001-02-02 2002-08-09 삼성전자 주식회사 Preamble detection method and device in packet data transmission system
US6574267B1 (en) 1999-03-22 2003-06-03 Golden Bridge Technology, Inc. Rach ramp-up acknowledgement

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20000014424A (en) * 1998-08-17 2000-03-15 윤종용 Apparatus and method for transmitting preamble of access channel
US6574267B1 (en) 1999-03-22 2003-06-03 Golden Bridge Technology, Inc. Rach ramp-up acknowledgement
KR20020064575A (en) * 2001-02-02 2002-08-09 삼성전자 주식회사 Preamble detection method and device in packet data transmission system

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Che-Li Lin, "Investigation of 3rd generation mobile communication RACH transmission", IEEE VTC 2000

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