KR100885744B1 - Method and system for using frame number in wireless communication network - Google Patents

Abstract

The present invention relates to a method and system for using a frame number in a wireless communication network, comprising the steps of: generating, by a base station, an absolute frame number based on a GPS synchronization clock; The base station generates a shared frame number for sharing between the base station and the terminal based on the absolute frame number and segment information identifying the sector of the base station, and transmits the shared frame number to the terminal by including in the DL_MAP message step; Receiving, by the terminal, a DL_MAP message and obtaining the shared frame number from the DL_MAP message; And generating, by the terminal, a PRBS for pilot modulation by using a least sign bit (LSB) of a predetermined digit among binary bit sequences corresponding to the shared frame number as an initial sequence of a pseudo random binary sequence (PRBS) generator. It is characterized by.

Description

Method and system for using frame number in wireless communication network {Method and system for using frame number in wireless communication network}

1 is a diagram illustrating AAS Zone allocation requiring synchronization.

2 is a diagram illustrating long PUSC allocation.

3 shows a generator of the downlink and uplink PRBS (Pseudo Random Binary Sequence).

4 is a block diagram illustrating a configuration of an embodiment of an apparatus for frame number synchronization of a base station system according to the present invention.

5 illustrates operation of sharing frame numbers between a base station system and a terminal in a wireless communication network.

6 is a flowchart illustrating an embodiment of a method for frame number generation according to the present invention.

7 is a flow chart illustrating one embodiment of the present invention using an absolute frame number (x).

8 is a block diagram showing a configuration of another embodiment of an apparatus for frame number synchronization according to the present invention.

9 is a flowchart illustrating another embodiment of a method for frame number synchronization according to the present invention.

10 is a flow chart illustrating another embodiment of the present invention using an offset.

The present invention relates to intersystem synchronization in a wireless network, and more particularly, to a method and system for using frame numbers in a wireless communication network.

In mobile services, for example WiMax services, there are many services that require synchronization. For these services, it would be convenient if the frame number carried by the DL-MAP is synchronized between all base stations. For example, synchronization is required for zone allocation for beamforming services. The beamforming operation requires synchronized AAS AMC zone boundary assignment between all base stations to support interference cancellation as shown in FIG. 1.

In addition, the allocation of long PUSC also requires synchronization between all base stations. In FIG. 1, only one slot duration of a PUSC zone is not sufficient to transmit a UL MAC management message having a large MAC PDU. Thus, as shown in FIG. When transmitting a MAC message having a MAC PDU of the same size, the base station allocates a long PUSC, and synchronization between the base stations is required.

In addition, synchronization is required in an action time and a fast ranging IE for a handover service. In order to reduce the handover wait time to the target base station by eliminating contention based on the CDMA code ranging process, the target base station allocates a fast ranging IE for the terminal to transmit the RNG-REQ message. The serving base station informs the terminal when a fast ranging IE message is to be allocated through the action time parameter in the MOB_BSHO-RSP. The action time refers to a frame offset until the fast ranging IE is allocated at the target base station.

To do this, the serving base station gathers the planned fast ranging IE assignments of the candidate target base stations, determines the action time from this information (usually the longest value up to the assignment), and when assigning the fast ranging IE, the candidate target base station. Feedback them. All these operations are performed via the R6 or R8 network interface. Considering the various network delays for this operation, the base stations involved in this operation need to be synchronized or share frame number information.

In case of providing MBS service, synchronization is also required for MBS-MAP and MBS_DATA_IE. The multiple base station MBS service, defined in IEEE802.16, enforces macro diversity support between multiple base stations. In macro diversity operation, MBS data in the same MBS zone should be identical. This means that the originator of the MBS data must control the transmission of all base stations in the same MBS zone. And it is almost impossible without knowing the frame numbers of all base stations in the MBS zone.

Synchronization is also required for paging services. A UE in idle mode may move from one base station to another without explicit binding in the paging group. This means that if the terminal has received paging cycle and paging offset information from the base station, it will try to listen to the MOB_PAG-ADV based on the received paging information even if it moves to another base station.

To support this operation, base stations in a paging group need to synchronize transmission time and paging messages, which requires frame number synchronization or sharing of frame numbers between base stations in the paging group.

Synchronizing means what the Nth outgoing data should be and what the structure of the Nth frame should be. For example, if there are two base stations, when the number of frames to be sent is n + 3 th, it is necessary to share what the n + 3 th message is or what the n + 3 th frame is between base stations. There is a need. If the base station is activated and the frame number at this time is n, and if it attempts to send a fast ranging IE to the n + 3 th frame, if the synchronization is not performed, the n + 3 th frame may be different for each base station. have.

3 shows a generator of downlink and uplink PRBS (Pseudo Random Binary Sequence). As shown in FIG. 3, the initial sequence 11 bits for generating PRBS is 4 bits of 4 Least Significant Bits (LSBs) of a frame number in the case of uplink, 2 bits of a predetermined value, and 5 LSBs of IDcell. Five bits are used to generate an uplink PRBS for pilot modulation. However, if the frame number is synchronized and identical among all base stations, 6 bits, which are 6 LSBs of PRBS, are the same for all base stations, and there may be up to 32 different initial sequences using 5 bits for IDcell.

If we assume that each base station has three sectors, the 32 initial sequences can cover only 10 base stations. As such, since the combination of the PRBS initial sequence for pilot modulation is reduced, there is a high possibility that the base station misinterprets the interference of another terminal having the same PRBS initial sequence as a signal. This is because the base station can distinguish interference by the difference of pilots.

Frame number synchronization is not a requirement for mobile WiMAX systems. Thus, some of the neighboring base stations of one base station are likely to be base stations of another vendor, and it is difficult to expect that frame numbers between base stations of other vendors may be synchronized. Therefore, if the system is designed and implemented assuming that all base stations are synchronized, the synchronization problem may be a limiting factor of the system.

In order to provide mobile WiMAX services as described above, frame number synchronization is required between base station systems. However, when frame number synchronization is performed between base station systems, interference problems are generated, for example, by generating an uplink PRBS signal. In the case of vendor base station systems, there is a problem in providing a service because frame number synchronization is not performed between the base station systems, and a solution for this is required.

The present invention has been made to solve the above problems and proposed elements, and provides a method and system using a frame number in a wireless communication network to improve the performance of the system.

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Another object of the present invention is to provide a frame number using method for a signal for pilot modulation to reduce interference between terminal signals.

In order to solve the technical problem to be achieved by the present invention, a method using a frame number in a wireless communication network according to the present invention, the base station generating an absolute frame number based on the GPS synchronization clock; The base station generates a shared frame number for sharing between the base station and the terminal based on the absolute frame number and segment information identifying the sector of the base station, and transmits the shared frame number to the terminal by including in the DL_MAP message step; Receiving, by the terminal, a DL_MAP message and obtaining the shared frame number from the DL_MAP message; And generating, by the terminal, a PRBS for pilot modulation by using a least sign bit (LSB) of a predetermined digit among binary bit sequences corresponding to the shared frame number as an initial sequence of a pseudo random binary sequence (PRBS) generator. Characterized in that.

In order to solve the technical problem to be achieved by the present invention, a system using a frame number in a wireless communication network according to the present invention, an absolute frame generation unit for generating an absolute frame number based on the GPS synchronization clock, the absolute frame number and the A base station including a shared frame generation unit configured to generate a shared frame number for sharing between the base station and the terminal based on segment information identifying a sector of the base station; And a receiver for receiving a DL_MAP message including the shared frame number from the base station, and using a LSB (Least Significant Bit) of a predetermined number of binary bit sequences corresponding to the shared frame number as an initial sequence for PRBS for pilot modulation. It characterized in that it comprises a terminal including a PRBS generator for generating (Pseudo Random Binary Sequence).

In order to solve the other technical problem to be achieved by the present invention, a method of using a frame number in a terminal of a wireless communication network according to the present invention, sharing for sharing between the base station and the terminal from the DL_MAP message included in the frame transmitted from the base station Obtaining a frame number; And generating a PRBS for pilot modulation using an LSB (Least Significant Bit) having a predetermined number of binary bit sequences corresponding to the shared frame number as an initial sequence of a Pseudo Random Binary Sequence (PRBS) generator. The shared frame number is set based on an absolute frame number based on a GPS synchronization clock and segment information identifying a sector of the base station.

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Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments. For reference, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted in the following description.

4 is a block diagram illustrating a configuration of an apparatus for synchronizing frame numbers in a base station system according to the present invention, including an absolute frame number generator 400 and a shared frame number generator 420. The segment information transmitter 440 and the DL_MAP transmitter 460 may be further included.

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The absolute frame number generator 400 generates an absolute frame number commonly used by each base station using a GPS clock. The GPS is mounted at each base station. Generate absolute frame number x using GPS clock. The shared frame number generation unit 420 generates a shared frame number (or virtual frame number) by adding a segment number to the absolute frame number x, where the shared frame number corresponds to terminals belonging to the base station. Frame number generated individually for sharing. If the base station is composed of three sectors of α, β, and γ, α may be assigned to 0, β to 1, and γ to 2. In this case, the shared frame number is the sum of the absolute frame number and the segment number, and thus x + α, x + β, and x + γ. The shared frame number is transmitted to the terminal so that the terminal can use it as an initial sequence of a pseudo random binary sequence (PRBS) generator for uplink pilot modulation. The segment information transmitter 440 transfers the segment information to another base station. The segment information may be transmitted using a message previously exchanged between base stations. The DL_MAP transmitter 460 transmits the shared frame number to the terminal using DL-MAP.

5 illustrates a frame number sharing operation between a base station system and a terminal according to the present invention in a wireless communication network. In FIG. 5, the absolute frame number generator 400 is included in a hardware abstraction layer (HAL), where the hardware abstraction layer may correspond to a physical layer and a lower medium access control (LMAC) layer. It can be implemented in field-programmable gate arrays (FPGAs) and DSP processors. The shared frame number generator 420 is included in an upper medium access control (UMAC) layer and may be implemented in a MAC processor. The shared frame number may be transmitted using DL-MAP. That is, an absolute frame number is generated from a hardware abstraction layer (HAL) by receiving a GPS clock, and the UMAC obtains an absolute frame number from the HAL using a GETFrame Number. Periodically, the frame number is given to UMAC by generating an absolute frame number x from the GPS clock. Since UMAC knows its own segment number, it adds a segment number to an absolute frame number to generate a shared frame number, that is, x + 0, x + 1, and x + 2, and transmits it by using DL-MAP.

The method assumes that each base station generates a common absolute frame number based on the GPS clock. The shared frame number (or virtual frame number) is generated using the absolute frame number and the segment number, so that the sharing is performed in a PRBS generator having a polynominal X ₁₁ + X ₉ + 1 as shown in FIG. 3. In the case of generating the PRBS using the frame number (or the virtual frame number), the possibility of congestion of the PRBS is reduced. This is because the PRBS initial sequence is tripled from 32 to 96 by adding segment numbers. The advantage of this method is that no additional message exchange is needed to know the shared frame number of another cell. This is because the shared frame number can be inferred from its own absolute frame number and the segment information of the received neighbor base station.

6 is a flowchart illustrating an embodiment of a method for frame number generation according to the present invention. First, an absolute frame number x is generated based on the GPS clock. (Step S600) A shared frame number is generated by adding a segment number to the absolute frame number x. (Step S620) The segment number is a three sector base station. It can be set to 0, 1, 2. The base station consists of three sectors, and each sector is added with 0, 1, and 2 when alpha, beta, and gamma. When receiving information with a neighbor base station, the base station is supposed to exchange segment alpha, beta, and gamma information with each other. If the base station knows its generated absolute frame number and if the corresponding sector of the base station is alpha, beta or gamma, it can infer what the current shared frame number is. In this case, there may be a step of transmitting additional segment information for delivering segment information to the neighboring base station.

7 is a flow chart illustrating one embodiment of the present invention using an absolute frame number (x). Here, the absolute frame number must be synchronized between all base stations providing periodic synchronization and macro diversity. If the frame is 5 msec, 200 frames may be generated in one second, and thus, the frame number increases by 200 after one second. Thus, knowing the GPS clock time and segment information enables sharing of the shared frame number, so that the frame number of the target base station can be easily synchronized with the target base station.

For the PRBS for pilot modulation, the problem is how far the terminals using the same PRBS overlap. The IDcell identification number used for PRBS is 5 bits, so the number is 32. This can be said that IDcell may overlap in a relatively close distance. However, using three sector numbers (alpha, beta, gamma) increases the number of PRBSs that can be generated, which can be said to overlap IDcells at some distance.

The present invention adds segment numbers 0, 1 and 2 to this value at some instant, i.e., generating frame number x based on the GPS clock. Since the frame generation period is 5msec, 200 frames are generated in 1 second. When a few frames tell the base station what to do, the other base station can know the segment information through the information provided by the neighbor base station, and this enables synchronization between the base stations so that it knows exactly what to do at any moment. have. As a result, the number of PRBS sequences increases, and the synchronization can be precisely matched to each other.

In the terminal using the frame number, the virtual frame number is first obtained from the received DL _MAP message, and the initial sequence is determined using some bits of the frame number. Then, a PRBS (Pseudo Random Binary Sequence) for pilot modulation is generated using a PRBS generator having the initial sequence as an initial value. The virtual frame number may be generated by absolute frame number and segment information.

8 is a block diagram showing a configuration of another embodiment of an apparatus for frame number synchronization according to the present invention, and includes a frame number requesting unit 800, a frame number receiving unit 820, an offset calculating unit 840, and a frame. And a number calculator 860.

The frame number request unit 800 requests a frame number from at least one neighboring base station using a GPS clock. The frame number receiving unit 820 receives a frame number in response to the request from the frame number requesting unit 800 from a neighboring base station.

When the frame number is received, the offset calculator 840 calculates an offset value corresponding to the difference by comparing the frame number with its own frame number. For example, if the frame number of the neighboring base station is requested in x sec, and if the frame number b of the neighboring base station is received at that time, the offset calculation unit 840 has its own frame number a and the frame number b of the neighboring base station. Find the offset of. The offset may be a-b. If the frame number of the neighboring base station is c at GPS time x sec, the offset becomes a-c.

The frame number calculator 860 calculates a frame number of a neighbor base station using the offset value and the GPS synchronization clock. Using this method, 512 PRBS sequences can be used. According to this method, since each base station is synchronized with the GPS clock, the base station asks for the frame number of the other party for a specific time x synchronized and informs its own frame number. This gives you the frame number at the exact moment. It may share its frame number information at the nth instant over the network. This method is cumbersome to send and receive messages, but it has the advantage of being able to write 512 things.

9 is a flowchart illustrating another embodiment of a method for frame number synchronization according to the present invention. First, a frame number is requested to at least one neighboring base station using the synchronization clock at a specific synchronization clock time (step S900). The frame number request can ask for a frame number through a network. Request the frame number of the other base station. The specific synchronization clock is preferably a clock signal based on a GPS signal. When the frame number is received from the neighboring base station (step S920), an offset value is calculated by comparing with the frame number of the neighboring base station (step S940). The frame number information of the neighboring base station is calculated using the offset value and the synchronous clock time. (Step S960) If the times of all the base stations are synchronized based on GPS, it is possible to know the frame numbers of the other base stations at a specific time, and the offset is obtained by comparing the frame number with its own frame number at that time. Can be calculated

10 is a flow chart illustrating another embodiment of the present invention using an offset. When there are base stations A, B, and C, assuming that the GPS clock is x sec, the frame number of base station A is a, the frame number of base station B is b, and the frame number of base station C is c. At this time, the base station A requests the base station B the frame number of the base station B at the GPS clock x sec. Base station B then sends its frame number b at GPS clock x sec to base station A. When the base station A receives the frame number b from the base station B, the base station A compares its frame number a with the frame number b of the base station B and calculates the offset a-b. Similarly, base station C proceeds in the same manner as that of base station B to calculate offset a-c. In this case, the base station A knows the frame numbers of the base station B and the base station C and can synchronize more accurately by compensating the offset, so that the specific operation can be performed at a specific time.

The method requires the exchange of frame number requests and responses but has the advantage that 4 LSBs of frame numbers for PRBS generation can be fully utilized. To do this, it is necessary to clarify the interface between the intra module or the inter base station as well as the module responsible for mapping GPS time and frame number.

The base station transmits an offset between the current frame number and the frame to which a specific operation should be performed, and requests the terminal to perform a certain operation.

On the other hand, the present invention described above can also be embodied as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, hard disks, optical data storage devices, and also in the form of carrier waves (for example, transmission over the Internet). It includes what is implemented. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. And functional programs, codes and code segments for implementing the present invention can be easily inferred by programmers in the art to which the present invention belongs.

Although the present invention has been described in detail with reference to preferred embodiments, it will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without changing the technical spirit or essential features thereof. The examples are to be understood in all respects as illustrative and not restrictive.

In addition, the scope of the present invention is specified by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention. Should be interpreted as

According to the present invention, various mobile WiMAX services can be provided through frame number synchronization. In addition, it is possible to efficiently provide frame synchronization between systems in a wireless network where frame number synchronization is not a requirement. In addition, by providing a frame number for the pilot signal modulation signal has the effect of reducing the possibility of the interference signal generation of the pilot signal modulation signal from the terminal. It also has the effect of solving the design and implementation constraints of frame number synchronization.

Claims (10)

In a method using a frame number in a wireless communication network, The base station generating an absolute frame number based on the GPS synchronization clock; The base station generates a shared frame number for sharing between the base station and the terminal based on the absolute frame number and segment information identifying the sector of the base station, and transmits the shared frame number to the terminal by including in the DL_MAP message step; Receiving, by the terminal, a DL_MAP message and obtaining the shared frame number from the DL_MAP message; And Generating a PRBS for pilot modulation by using, by the terminal, an initial sequence of a pseudo random binary sequence (LSB) generator using a LSB (Least Significant Bit) of a predetermined number of binary bit sequences corresponding to the shared frame number; How to use frame numbers. The method of claim 1, The segment information is generated by using the identification information of the base station and the sector identification information of the base station. delete In a system using a frame number in a wireless communication network, An absolute frame generation unit for generating an absolute frame number based on a GPS synchronization clock, and a shared frame for generating a shared frame number for sharing between the base station and the terminal based on the absolute frame number and segment information identifying a sector of the base station; A base station including a generation unit; And PRBS for pilot modulation using a receiving end for receiving a DL_MAP message including the shared frame number from the base station and an LSB (Least Significant Bit) of a predetermined number of binary bit sequences corresponding to the shared frame number as an initial sequence; And a terminal including a PRBS generator for generating a pseudo random binary sequence. The method of claim 4, wherein The base station further includes a frame information transmitting unit for transmitting the segment information to another base station. The method of claim 4, wherein The base station further comprises a DL_MAP transmission unit for transmitting the shared frame number to the terminal using the DL_MAP. delete delete In a method of using a frame number in a terminal of a wireless communication network, Obtaining a shared frame number for sharing between the base station and the terminal from a DL_MAP message included in a frame transmitted from the base station; And Generating a PRBS for pilot modulation using an LSB (Least Significant Bit) of a predetermined number of binary bit sequences corresponding to the shared frame number as an initial sequence of a pseudo random binary sequence (PRBS) generator, Wherein the shared frame number is set based on an absolute frame number based on a GPS synchronization clock and segment information identifying a sector of the base station. The method of claim 9, The segment information is generated by using the identification information of the base station and the sector identification information of the base station.

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