KR20060106467A - Method and apparatus for synchronizing frame number using gps in broadband mobile system - Google Patents

Abstract

The present invention relates to a frame number synchronization method using a satellite navigation device in a broadband mobile communication system, receiving time information from the satellite navigation device, converting the time information into a value for a frame duration, and converting the time information. And determining a frame number by modularizing the obtained value into a predetermined natural number.

Frame Number, Satellite Navigation System

Description

Method and apparatus for synchronizing frame number using satellite navigation device in broadband mobile communication system {METHOD AND APPARATUS FOR SYNCHRONIZING FRAME NUMBER USING GPS IN BROADBAND MOBILE SYSTEM}

1 is a diagram illustrating a message format of a downlink map according to the present invention.

2A and 2B illustrate a PHY synchronization field and its subfields according to the present invention.

3 is a block diagram of a system showing a process of synchronizing frame numbers according to an embodiment of the present invention;

4 is a block diagram of a system illustrating a process of estimating a handoff start time according to an exemplary embodiment of the present invention.

5 is a diagram illustrating a process of determining a frame number at each base station according to an embodiment of the present invention.

6 is a view showing a frame number synchronization apparatus using a satellite navigation apparatus according to an embodiment of the present invention.

The present invention relates to a method and apparatus for synchronizing frame numbers using a satellite navigation apparatus in a broadband mobile communication system. In particular, the present invention relates to an operation of idle mode operation, handoff, etc. by synchronizing frame numbers transmitted through a forward channel between base stations in a broadband mobile communication system. The present invention relates to a method and an apparatus capable of improving performance.

Today, due to the development of the mobile communication industry and the user's demand for the Internet service, the need for a mobile communication system capable of efficiently providing the Internet service is increasing. Existing mobile communication networks have been developed mainly for voice services, which have disadvantages of relatively small data transmission bandwidth and high usage fee. Therefore, technology that can transmit not only voice but also data from a mobile communication network to a broadband is continuously introduced. In particular, the IEEE 802.16 standardization group of the Institute of Electrical and Electronics Engineers (IEEE), one of the international standardization organizations, is a standard for providing wireless broadband Internet services to terminals. The IEEE 802.16d standard, which integrates standards such as a and 802.16b, is enacted. At the same time, the IEEE 802.16e standard is being enacted to improve the IEEE 802.16d and provide wireless broadband Internet services to terminals.

 The IEEE 802.16d / e standard has a wider bandwidth of data than conventional wireless technology, so that a large amount of data can be transmitted in a short time, and all users share a channel to efficiently use the channel. It is possible. In addition, in IEEE 802.16d / e system, all users connected to the base station share a common channel, and each user uses the channel in each uplink and downlink frame. Channel characteristic information and channel access information should be informed so that they can be used separately.

In addition, in the IEEE 802.16d / e system, channel information is divided into uplink channels and downlink channels, information about each channel is defined in the form of TLV (Type, Length, Value), DCD (Downlink Channel Descriptor), and UCD (Uplink Channel Descriptor). ) And informs the terminal of the characteristic information about the channel by transmitting it to all users at regular intervals. That is, the base station broadcasts uplink and downlink information for accessing the base station every frame so that the terminal can access the uplink and downlink channels. The uplink and downlink information is called an UL map and a DL map, respectively.

At this time, in IEEE 802.16d / e, the UE uses a frame duration and a frame number of a synchronization field of a downlink map (DL-MAP) to transmit information about a frame size and a frame sequence change. Get In addition, in IEEE 802.16d / e, the frame number of the synchronization field of the downlink map is not specially regulated for each base station. However, when not used in synchronization with each base station, there is a problem that the terminal needs to recalculate the next general base station paging interval when the handoff is performed in the idle mode, or increases the probability of not receiving the paging.

Accordingly, an object of the present invention is to provide a method and apparatus for transmitting the same value at the same time by synchronizing frame numbers between base stations in a broadband mobile communication system.

Another object of the present invention is to provide a method and apparatus for skipping a procedure for recomputing the next general base station paging interval when a user wakes up by moving to another base station in an idle mode by using a frame number as the same value between base stations in a broadband mobile communication system. To provide.

It is still another object of the present invention to provide a method and apparatus for reducing the probability of paging loss when a user wakes up by moving to another base station in an idle mode by using the same frame number between base stations in a broadband mobile communication system.

It is still another object of the present invention to provide a method and apparatus for providing a frame number as a reference point for a handoff function in an inter-base station backbone communication of a broadband mobile communication system.

In accordance with another aspect of the present invention, there is provided a frame number synchronization method using a satellite navigation device in a broadband mobile communication system, the method comprising: receiving time information from the satellite navigation device; And converting the information into a value for a frame duration, and determining a frame number by modularizing the converted value into a predetermined natural number.

Another embodiment of the present invention is a frame number synchronization apparatus using a satellite navigation apparatus in a broadband mobile communication system, comprising: a time information receiver for receiving time information from the satellite navigation apparatus, and a frame number using the received time information; A frame number calculating unit for calculating a number, a frame number storing unit storing the calculated frame number, a signal transmitting and receiving unit for directly and indirectly transmitting and receiving a predetermined signal with an upper node, and a communication state with the upper node or a neighboring node. And a communication state control unit controlling the frame number.

Hereinafter, the operation principle of the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals refer to the same elements as shown in the drawings, even though they may be shown on different drawings, and detailed descriptions of related well-known functions or configurations are not required in the following description of the present invention. If it is determined that it can be blurred, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

1 is a diagram illustrating a message format of a downlink map according to the present invention.

Referring to FIG. 1, the downlink includes parameters such as a PHY synchronization field, a DCD count, a base station ID, a number of elements, and the like.

The PHY synchronization field depends on the specification of the physical layer and will be described in detail in FIG. 2 as a field including the main components of the present invention. The DCD count matches the DCD count setting change value. The base station ID is a field for identifying the base station. The number of elements represents the number of information elements IE.

2A and 2B illustrate a PHY synchronization field and its subfields according to the present invention.

Referring to FIG. 2A, the PHY synchronization field includes a frame duration code and a frame number. The frame duration code is 8 bits and the frame duration according to each frame duration code is shown in FIG. 2B. In addition, the frame number is 24 bits, which is increased by one for each frame.

Referring to FIG. 2B, the relationship between the frame duration and the frame duration code is as follows. The frame duration corresponding to the frame duration code value is determined differently according to the physical layer. For example, if OFDMA is used as the physical layer, if the frame duration code is 0x01, the frame duration is 2ms, if the frame duration code is 0x02, the frame duration is 2.5ms, and if the frame duration code is 0x03, the frame duration Is 4ms. The base station and the terminal obtain information on the size of the frame and the frame sequence change by using the frame duration and the frame number.

3 is a block diagram of a system showing a process of synchronizing frame numbers according to an embodiment of the present invention.

Referring to FIG. 3, the system for synchronizing the frame number includes a satellite 300, a serving base station 320, a target base station 350, a backbone network 330, and a terminal 340.

The serving base station 320 and the target base station 350 are connected to each other via a backbone network 330 including an upper node to transmit and receive state information of each other, and the satellite 300 of the global positioning system (GPS) The frame information is received and determined by synchronizing 310 with the frame number. The frame number serves as a basis for determining whether the UE wakes up at the correct time and monitors the frame in the sleep mode or the idle mode. If the UE is not in the expected frame number but in the sleep mode, it wakes up in the awake mode and starts the normal mode. In the idle mode, the UE wakes up again at the calculated time by recalculating the next general base station paging interval.

That is, in IEEE 802.16, the frame number of the synchronization field of the downlink map does not have to be synchronized for each base station. However, when the synchronization is not used for each base station, when the terminal 340 is handed off in the idle mode, the target base station is used. This is because the probability of recalculating the paging interval or not receiving the paging increases. In other words, when the terminal 340 moves in the idle mode and enters the target base station 350, if the frame number of the target base station 350 is different from the frame number of the serving base station 320, paging using PAGING_CYCLE and PAGING_OFFSET. This is because it is different from the serving base station 320 at the time point. The paging time point is calculated as in Equation 1 below.

N _frame modulo PAGING_CYCLE == PAGING_OFFSET

That is, the terminal 340 does not receive the paging received before the first terminal paging listening interval moves to another base station in the idle mode. The paging occurring from the next time is performed at the time obtained by calculating the next general base station paging interval from the terminal paging listening interval, so that the terminal 340 can receive it.

As described above, the terminal may skip the procedure of re-computing the next general base station paging interval when waking up from the base station to which it belongs to another base station in the idle mode, since the frame numbers of all base stations are set to the same value. And the probability of paging loss can be reduced.

4 is a configuration diagram illustrating a system for estimating handoff start time according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the system for synchronizing the frame number includes a serving base station 320, a target base station 350, a backbone network 330, and a terminal 340. The serving base station 320 and the target base station 350 may calculate estimated handoff start time information through the synchronized frame number as shown in FIG. 3.

The base station predicts the MS Paging Listening Interval using the stored PAGING_CYCLE and PAGING_OFFSET when the UE transitions to the idle mode. After that, if there is data to be transmitted, the base station transmits a paging (PAG-ADV) message to the terminal.

If the terminal moves and wakes up from the previously calculated terminal paging listening interval, the probability of losing the paging message is increased if the frame number of the moved base station is different from the serving base station. Accordingly, by synchronizing the frame numbers between the base stations, it is possible to increase the probability of receiving a paging message regardless of which base station the terminal moves to.

That is, when the terminal handoffs, the correct handoff time is calculated using the estimated handoff start parameter of the handoff message. The estimated handoff start time information thus calculated is used to attempt fast ranging. Therefore, when handing off, the terminal 340 supports a function of quickly ranging from the target base station 350 without competing through fast ranging after the handoff.

In this case, the terminal 340 receives the base station handoff response (MOB-BSHO-RSP) message by using the estimated handoff start parameter when the handoff request is made to the serving base station 320, and after the predetermined frame transmission, the target base station 350. Information to be handed off to the serving base station 320 is transmitted.

In addition, the target base station 350 transmits a fast ranging information element (Fast Ranging IE) using this to allow the terminal to immediately transmit a ranging request (RNG-REQ) message. In this case, for the high-speed ranging, the backbone network 330 indicates at which point the high-speed ranging information element is transmitted for the terminal 340 handing off from the serving base station 320 to the target base station 350. In this case, since the network delay needs to be considered, the estimated handoff start information and the reference time information 400 are transmitted together.

As described above, when the base station transmits the estimated handoff start value from the serving base station to the target base station to support the fast ranging function during handoff, the target base station knows the exact time when the terminal is handed off by transmitting the frame number as reference information. Can be.

5 is a diagram illustrating a process of determining a frame number at each base station according to an embodiment of the present invention.

Referring to FIG. 5, each base station receives and stores time information from the satellite navigation apparatus in step 500. Each base station converts the time information into a value for a frame duration in step 510. Each base station modulates the converted value into a predetermined natural number in step 520 to determine a frame number. At this time, the predetermined natural number is 16777216 which is 2 ²⁴ because the frame number field of the map message is 24 bits. This process can be expressed as Equation 2 below.

Frame number = t modulo 16777216

Where t is [GPS time / frame duration], a unit of GPS time and frame duration is seconds, and the same frame duration is used.

The synchronized frame number may be used to determine a fast ranging function and an accurate handoff time point in the handoff. When the frame numbers are synchronized between the base stations as described above, the frame numbers may be used as reference points in the backbone communication between the serving base station and the target base station for handoff. When the estimated handoff start information determined through the handoff message with the terminal is transmitted to the target base station together with the frame number, the target base station accurately predicts the time remaining until the estimated handoff starts of the terminal and delivers the fast ranging information element to the terminal.

If the frame number is different between the base stations, the paging time point calculated by the target base station using PAGING_CYCLE and PAGING_OFFSET when the terminal moves from the idle mode to the target base station is different from the serving base station. Therefore, the next base station paging interval at the target base station should be recalculated, and the probability of not receiving paging until the first waking up from the moved base station increases. However, when the frame numbers are synchronized as described above, paging times calculated using PAGING_CYCLE and PAGING_OFFSET are also matched between other base stations, thereby increasing the probability of paging reception and omitting the procedure of recalculating the next base station paging interval. have.

6 is a view showing a frame number synchronization apparatus using a satellite navigation apparatus according to an embodiment of the present invention.

6, a time information receiver 600, a frame number calculator 610, a frame number storage 620, a signal transceiver 630, and a communication state controller 640 are included. Here, the time information receiver 600 receives time information from the satellite navigation apparatus, and the frame number calculator 610 calculates a frame number using the received time information. In addition, the frame number storage unit 620 stores the calculated frame number, and the signal transceiver 630 transmits and receives a predetermined signal directly or indirectly with an upper node, and the communication state controller 640 is an upper node. Alternatively, the communication state with the neighbor node is controlled using the frame number.

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 those equivalent to the scope of the claims.

In the present invention operating as described above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

The present invention synchronizes frame numbers between base stations in a broadband mobile communication system so that the paging reception probability does not decrease even when the mobile station moves in the idle mode because the paging timing calculated by the base station in the idle mode is matched. This can reduce the load of calculating the paging interval.

In addition, the present invention also has the effect that the frame number can be used as a reference point for delivering the correct handoff time to the target base station in the handoff.

Claims (5)

A frame number synchronization method using a satellite navigation apparatus in a broadband mobile communication system, Receiving visual information from the satellite navigation device; Converting the time information into a value for a frame duration; And modulating the converted value with a predetermined natural number to determine a frame number. The method of claim 1, The synchronized frame number is used as a reference time for measuring a delay of backbone communication between base stations. The method of claim 1, And wherein the synchronized frame number is used for a fast ranging function. The method of claim 1, The synchronized frame number is used as a reference for predicting the exact time when handoff between base stations. In the frame number synchronization apparatus using satellite navigation apparatus in a broadband mobile communication system, A time information receiver for receiving time information from the satellite navigation device; A frame number calculator for calculating a frame number using the received visual information; A frame number storage unit for storing the calculated frame number; A signal transceiver for directly and indirectly transmitting and receiving a predetermined signal with an upper node, And a communication state control unit controlling a communication state with an upper node or a neighbor node by using the frame number.

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