KR20060019482A - Apparatus and method on synchronization between base station and repeater in wireless broadband access network - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a base station and repeater synchronization synchronization device and method thereof in a portable Internet system.

2. The technical problem to be solved by the invention

The present invention provides a synchronization matching apparatus and method for synchronizing the entire system synchronization without causing interference to the TDD frame without modifying the TDD frame format in the OFDM / TDD base station and the OFDM / TDD relay period in the portable Internet system Its purpose is to.

3. Summary of Solution to Invention

According to the present invention, a base station and a relaying period synchronization device in a portable Internet system, by bypassing the signal transmitted from the base station to the repeater remote during the forward signal processing, and delays the base station signal by a first predetermined frame For transmitting through a first antenna, and delaying the signal received through the first antenna by the first predetermined frame when processing a reverse signal, and added to the reverse signal received from the repeater remote to deliver to the base station Repeater donor; And delaying a forward signal received from the repeater donor by a second predetermined frame when forward signal processing is transmitted through a second antenna, and delaying a signal received through the second antenna by the second predetermined frame when reverse signal processing. And the repeater remote for delivery to the repeater donor.

4. Important uses of the invention

The present invention is used in the portable Internet system.

Mobile Internet, System Synchronization, GPS, TDD Repeater, Base Station

Description

Apparatus and method on synchronization between base station and repeater in wireless broadband access network             

1 is a diagram illustrating a general base station cell configuration;

2 is an explanatory diagram showing a PPS and a 10 MHz clock received by a general GPS;

3 is an explanatory diagram illustrating a Tx / Rx frame synchronization matching process between base stations when the base stations of FIG. 1 use GPS;

4 is a diagram illustrating a connection configuration between a general urban area base station and an optical repeater remote;

FIG. 5 is an explanatory diagram showing a timing diagram between the urban area base station and the optical repeater remote of FIG. 4; FIG.

6 is a diagram illustrating a connection configuration between a general mountain area base station and an optical repeater remote;

FIG. 7 is an explanatory diagram showing a timing diagram between the mountain area base station and the optical repeater Remote of FIG. 6; FIG.

8 is a diagram illustrating an embodiment of a configuration and method of a base station and repeater synchronization synchronization device according to the present invention;

9 is an explanatory diagram showing a timing diagram between a base station and an optical repeater remote according to an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

10: base station 20: repeater donor (DONOR)

30: repeater remote (REMOTE)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for synchronizing relay periods with a base station in a portable internet system, and more particularly, to an orthogonal frequency division multiplexing (OFDM) / time division duplex (TDD) base station and an OFDM / TDD relay period in a portable internet system. The present invention relates to a synchronization matching device and a method for synchronizing entire system synchronization without causing interference in a TDD frame.

The basic concept of the portable Internet refers to "portable internet service that provides high-speed wireless Internet access anywhere, anytime while stopping and moving." Here, "stop and move" basically means that the Internet should be able to be flexibly connected to the indoors of homes and offices, as well as outdoors such as parks and streets, and "high speed" basically This means that the transmission speed of the high-speed wired Internet level (1 to 2Mbps per subscriber) must be supported.

Currently, it is a technology that enables high-speed wireless Internet access in the 2.3GHz band, and foreign technologies (i-burst, flash-OFDM, etc.) of WiBro (Wide Broadband) and WDSL (Wireless Digital Subscriber Line) technologies Wireless LAN (Local Area Network) improvement technology.

The portable Internet service of the 2.3 GHz band refers to a service that can provide a variety of information and contents by accessing the Internet at a high transmission speed in a stationary and walking state using a portable wireless terminal.

Currently, according to the ideas of communication experts, various types of terminals, such as a personal computer (Personal Computer) or a PDA (Personal Digital Assistants), are expected to be used as portable terminals. However, these early dedicated terminals are likely to evolve into integrated multi-mode terminals in the long term with the development of communication technology. Although mobility varies depending on the technology, it guarantees a slightly higher level of walking mobility than the current wireless LAN in the 2.4 GHz band.It also provides stable speeds above average 1 Mbps, depending on the technology. By providing, it is expected that smooth wireless internet will be possible.

The portable Internet utilizes the 2.3 GHz band to overcome the limitations of existing systems in terms of usage area and charges, and provides high-speed Internet access on the go as well as stationary at the quality and cost of Asymmetric Digital Subscriber Line (ADSL). Means Internet service.

The portable Internet is faster than the transmission speed in motion pursued by the existing IMT-2000 (International Mobile Telecommunication-2000), and unlike the WLAN (Wireless LAN) can provide Internet services in indoor as well as outdoor mobile environment.

In addition, the portable Internet supports handoffs between cells as in the existing mobile communication services, and provides seamless service while moving. In addition, as with wired Internet, the company seeks to maximize bandwidth efficiency in order to enable constant charge based connection. In other words, the aim of the present invention is to overcome the market limitations of existing mobile communication services by securing economic feasibility, and to provide the same internet access environment as wired lines using various portable computer terminals including notebook PCs.

On the other hand, in the current wireless communication market, where the securing of frequency is a big problem, a time division duplex (TDD) method that enables communication with a single frequency has been in the spotlight in recent years. Unlike the past, this is believed to be possible due to the development of parts and equipment that can be synchronized at the right time.

The TDD method can theoretically support the same service using timeslots smaller than the frequency division duplexing (FDD) method, and has a similar structure to the current Internet by using an asymmetrical arrangement of up / down time slots. It has the technical characteristics suitable for the transmission of the application. As a result, the frequency enables a high transmission rate without using only half as compared to the FDD scheme, thereby enabling a service at a relatively low cost.

Due to these characteristics, it has become a very attractive technology for wireless carriers, but in the meantime, it is very difficult to detect synchronization of time slot dynamic allocation and solve the problem of time delay according to transmission distance. I was hit. However, in recent years, the market has been widened by overcoming these problems with various technologies, and as mentioned above, since downlinks can be easily combined with many current wired Internet communication systems, they are in the spotlight again.

At present, there is no example of building a commercial service using a TDD optical repeater, but a system using a TDD scheme is considered. An optical repeater is considered in terms of cost and efficiency. However, due to the limitations of the TDD method, a limitation of the cell radius occurs, and when using an optical repeater, a radio propagation speed (3 x 108 m / s) and an optical fiber propagation speed ( Due to the difference between 2 x 108 m / s), the base station cell radius is reduced when using the optical repeater. In addition, due to the difference in propagation speed, synchronization between the system and the optical repeater does not match, causing interference in the TDD frame, thereby causing communication failure. To prevent this, synchronization of the entire TDD system is required. Looking at this in detail.

Next, a synchronization matching method in a conventional TDD system will be described.

In the case of the TDD system, since the same frequency band resources are allocated to the transmission (Tx) and the reception (Rx) in time division, synchronization matching is important between the system and the terminal and between the system and the system.                         

However, if the synchronization is inconsistent between the system and the terminal, it may affect not only the communication disconnection between the terminals, but also affect the neighboring terminals, thereby causing a malfunction or the communication interruption of all terminals in a system. In addition, when the synchronization is not consistent between the systems, the communication disconnection phenomenon is severe when the terminal handover occurs, and the communication interruption phenomenon occurs because the Tx and Rx frames cross each other at the cell boundary. Therefore, the maximum throughput can be obtained only if the synchronization is exactly matched between the systems. To this end, the proposed scheme is to synchronize synchronization using GPS.

For reference, the GPS (Global Positioning System) is installed and controlled by the U.S. Department of Defense (U.S. DoD). Although there are a number of general users of GPS around the world, the system is designed and operated militaryly for US military purposes.

Areas of use of GPS include precision measurement geodetic field (precision reference point measurement, GIS D / B construction and design), guided information acquisition field (induction measurement, civil engineering construction management, eyepiece guide system, AVLS / CNS And management systems), etc.), aviation sector (aircraft operation, aircraft monitoring, precision landing), ground transportation (IVHS, AVLN, cargo truck control, railway vehicle control, courier vehicle control, emergency and patrol vehicle control), maritime transport (ship) Navigation, waterway guidance, canal transport), space (satellite tracking, satellite attitude determination), military (guided weapons, precision bombing, reconnaissance, management), science (weather research, ocean current research, convective layer research, crustal motion observation) , Exploration (geological exploration, oil field exploration, ruins / relics exploration), resource management (farming resource management, fishery resource management, land management, forest management), leisure use (mountain climbing, sailing, hiking) and time measurement (reference time synchronization) , Time synchronization, communication system).

1PPS (1 Pulse Per Second) received from GPS is used to supply Universal Time Coordinated Time (UTC), precise time and frequency. Therefore, it is used as a precise time and frequency supply device in various applications such as cellular communication base stations such as cellular CDMA, PCS, Pager, WLL, IMT-2000, digital transmission system, power protection system, network time synchronization, and measurement equipment. high.

The GPS receiver using this satellite can be provided with time information in seconds and a reference clock of 10 MHz.

1 is a diagram illustrating a typical base station cell configuration.

In the case of a TDD system, transmission (Tx) and reception (Rx) of all base stations must be performed at a predetermined time so as not to degrade system performance.

In order to overcome this problem, a signal that needs to be received through GPS is required for synchronization matching, using a PPS signal as shown in FIG. 2. PPS is an easy signal for synchronizing the system with pulses that occur once per second to meet international standard times. In addition, as shown in FIG. 2, a 10MHz clock is received and used as a reference clock of the system.

TDD repeaters using GPS synchronize the synchronization of the entire system using the synchronization provided by GPS without having to interpret the TDD frame directly. Since the function implementation uses a GPS receiver, it is relatively simple to make a repeater and can be applied to other TDD repeaters.

However, the disadvantage is that the GPS receiver is expensive, and the use consideration is that the Hold Over function when the GPS reception is not accurate should minimize the effect on the whole system.

FIG. 3 illustrates Tx / Rx frame synchronization matching between base stations when the base stations of FIG. 1 use GPS.

According to the prior art, the service coverage of the system is determined by the Tx frame, the Rx frame, and the TTG (Transmit / teceive Transition Gap) and the RTG (Receive / transmit Transition Gap). However, in the case of regions with few subscribers and wide service areas, such as mountain wallpaper, the service construction cost is high. However, by using a repeater, a base station can accommodate coverage of a large area, thereby reducing service construction costs, thereby providing a better quality service at a lower service construction cost.

4 is a diagram illustrating a connection configuration between a general urban area base station and an optical repeater remote.

As shown in FIG. 4, in the downtown area, repeater remotes A, C, and D are arranged at equal intervals of 2 km in the base station, and repeater remotes B, E are disposed at 4 km, and the repeater remote is located at the base station. (REMOTE) F is placed at 6 km.

However, according to the prior art, looking at the delay timing (Delay Timing) between the urban base station and the optical repeater Remote (Remote) as shown in FIG.

As shown in FIG. 5, the delay increases according to the installation distance of the repeater remote, so that in the case of the repeaters remote B, E, and F, the received frames (Rx Frame) of the base station are It may affect the next transmission frame (Tx Frame) and the system may not operate normally, or part of the reception frame (Rx Frame) of the repeaters Remote B, E and F may be cut off. In addition, when control information is contained in a symbol before a Rx frame, communication itself becomes impossible.

6 is a diagram illustrating a connection configuration between a general mountain area base station and an optical repeater remote.

As shown in FIG. 6, in the mountain wallpaper, the base station of the village A where the base station is installed is 8 km from the repeater Remote B of the village B, 10 km to the repeater Remote C of the village C, and the repeater remote of the village D ( Remote) D is placed 5km away.

However, the delay timing between the mountain base station and the optical repeater Remote according to the prior art will be described with reference to FIG. 7.

Since the TDD frame is used, communication in a long distance may cause a communication failure because an intersection of a Tx frame and a Rx frame occurs. Solving the problems of such a TDD system may be a way to enable a low-cost TDD system.

In a TDD system, a radius of a cell that a base station can cover is determined by TTG and RTG. Therefore, it is not easy to enlarge the coverage area of the cell on the weak point that TDD has. In addition, since time division is performed, changes in the Tx frame and the Rx frame, or the TTG and RTG affect the entire TDD system. Therefore, a technique for increasing the cell coverage area without changing the structure of the transmission frame is urgently required.

The present invention has been proposed to solve the above problems, and in the portable Internet system, it is possible to match the entire system synchronization without causing interference in the TDD frame without modifying the TDD frame format in the OFDM / TDD relay period. It is an object of the present invention to provide a synchronization matching device and a method thereof.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. In addition, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In order to achieve the above object, the present invention provides a device for synchronizing relaying periods with a base station in a portable Internet system, wherein the signal transmitted from the base station is bypassed to the repeater remote at the time of forward signal processing and the base station signal is removed. Delay by one predetermined frame and transmit the signal through the first antenna, and during the reverse signal processing, delay the signal received through the first antenna by the first predetermined frame and add it with the reverse signal received from the repeater remote. A repeater donor for delivery to the base station; And delaying a forward signal received from the repeater donor by a second predetermined frame when forward signal processing is transmitted through a second antenna, and delaying a signal received through the second antenna by the second predetermined frame when reverse signal processing. It characterized in that it comprises a repeater remote for transmitting to the repeater donor.

Meanwhile, the present invention provides a method for synchronizing relay periods with a base station in a wireless communication system. In a forward signal processing, a repeater donor bypasses a signal transmitted from a base station to a repeater remote and simultaneously transmits a base station signal to a first base station signal. Delaying by a predetermined frame and transmitting through a first antenna; In a forward signal processing, repeating, by a repeater remote, a forward signal received from the repeater donor by a second predetermined frame and transmitting the delayed forward signal through a second antenna; In a reverse signal processing, relaying the signal received through the second antenna to the repeater donor by delaying the signal received through the second antenna by the second predetermined frame; And delaying, by the repeater donor, the signal received through the first antenna by the first predetermined frame and adding the reverse signal received from the repeater remote to the base station during reverse signal processing. It features.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

8 is a diagram illustrating an embodiment of a configuration and method of a base station and repeater synchronization synchronization device according to the present invention.

In general, the frequency conversion repeater is composed of a donor unit and a remote unit, and the donor unit is located in a callable area and the remote unit is located in a radio shade area, so that the frequency conversion is performed on an idle channel that is not used as a service channel between the two units. Link with signal to enable service in radio shade area.

In order to match the overall system synchronization without interfering with the TDD frame, when the forward signal is generated, the repeater donor 20 delays the signal by one frame and transmits it to the antenna 24. And, the signal transmitted to the repeater remote (Remote) 30 transmits the signal of the base station to the repeater remote (Remote) 30 without manipulation. Then, the repeater remote 30 delays the forward signal by "1 frame-optical distance delay" and transmits it through the antenna 33.

On the other hand, in the case of the reverse signal, the repeater remote 30 delays the signal by "1 frame-optical distance delay" and transmits the signal to the repeater donor 20, and the repeater donor ( In the 20), the signal received through the antenna 24 is delayed by one frame to add a frame delay to the base station 10 by summing with a reverse signal received from the repeater remote 30. Send it out.

Accordingly, as shown in FIG. 8, the base station and the repeater synchronous synchronization device according to the present invention simultaneously bypass the signal transmitted from the base station 10 to the repeater remote 30 during forward signal processing. The base station signal is delayed by the first predetermined frame and transmitted through the antenna 24, and the reverse signal received from the relay remote 30 by delaying the signal received through the antenna 24 by one frame during the reverse signal processing. The repeater donor 20 for adding the signal to the base station 10 and transmitting the signal to the base station 10 and delaying the forward signal received from the repeater donor 20 by "1 frame-wide distance delay" for the antenna 33. And a repeater remote 30 for transmitting the signal received through the antenna 33 to the repeater donor 20 by delaying the signal received through the antenna 33 during reverse signal processing. All.

The repeater donor 20 repeats the base station signal by one frame while bypassing the signal transmitted from the base station 10 to the repeater remote 30 when the repeater donor processes the forward signal. A first frame delay unit 21 for transmitting through the antenna 24 and a second frame delay unit for delaying a signal received through the antenna 24 by one frame during reverse signal processing. 22) and an adder 23 for adding the reverse signal received from the repeater remote 30 and the signal delayed by one frame by the second frame delay unit 22 to the base station 10 and transmitting the signal.

In addition, the repeater remote 30 delays the forward signal received from the repeater donor 20 by '1 frame-line delay' when processing the forward signal. In the reverse signal processing, the first delay unit 31 for transmitting the signal through the antenna 33 delays the signal received through the antenna 33 by '1 frame-line delay' and repeater donor ( And a second delay unit 32 for transmitting to 20).

The base station (BTS) 10 transmits a forward signal to the portable Internet base station (relay donor) 20 and receives a reverse signal.

The repeater donor 20 transmits a forward signal coming down from the base station 10 to the repeater remote 30 and delays one frame with an input signal from the base station 10. The quasi signal is transmitted through an antenna 24.

In addition, in the repeater donor 20, a 'one frame' is applied to a reverse signal input through the repeater remote 30 and a reverse signal input through the antenna 24. The signal corresponding to the delay corresponding to the delay is transmitted to the adder 23. Then, the adder 23 sums the signal delayed by one frame in the frame delay unit 22 and the signal of the repeater remote 30 and transfers the signal to the base station 10.

On the other hand, the repeater remote (Remote) 30 is delayed by "1 Frame-Line Delay" forward signal transmitted from the repeater donor (20) to the antenna (33). In addition, the reverse signal received through the antenna 33 is also transmitted to the repeater donor 20 by delaying by "1 frame-line delay" like the forward signal.

When the present invention is applied to the connection configuration between the urban area base station and the optical repeater remote as shown in FIG. 4, the timing and repeater donor 20 of the frame transmitted and received by the base station 10 The timing of the signals inputted and outputted from the controller is illustrated in FIG. 9.

As shown in FIG. 9, it can be seen that the forward frame transmitted from the base station 10 to the repeater donor 20 is transmitted with a '1 frame delay'. In addition, in the case of the reverse frame (Reverse Frame), it can be seen that the time delay of two frames are delivered to the base station 10.

Each repeater remote 30 processes with a 1 frame delay for the forward frame so that 5us of delay per 1Km of optical cable is limited without any distance (theoretical about 5ms frame). Up to 1000 km).

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily implemented by those skilled in the art will not be described in more detail.                     

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

The present invention as described above has the effect of increasing the cell coverage area without changing the structure of the transmission frame and matching the entire system synchronization without causing interference to the TDD frame.

In addition, the present invention has the advantage of reducing the complexity of the system and reducing the burden on the development cost compared to modifying the frame itself and the hardware can be simple to occupy the price advantage.

Claims (10)

A device for synchronizing relay periods with a base station in a wireless communication system, Bypassing the signal transmitted from the base station to the repeater remote in the forward signal processing and simultaneously delaying the base station signal by a first predetermined frame and transmitting it through the first antenna, and in the reverse signal processing, the first antenna A repeater donor for delaying the signal received through the first predetermined frame and adding the reverse signal received from the repeater remote to the base station; And Delay the forward signal received from the repeater donor by a second predetermined frame when forward signal processing, and transmit it through the second antenna, and delay the signal received through the second antenna by the second predetermined frame when reverse signal processing. The repeater remote for delivery to the repeater donor In the portable Internet system comprising a base station and the relay period synchronization matching device. The method of claim 1, The first predetermined frame, An apparatus for synchronizing relay periods with a base station in a portable Internet system, characterized in that one frame. The method of claim 1, The second predetermined frame is, A base station and repeater synchronization synchronization device in a portable Internet system, characterized in that one frame is obtained by subtracting a wide distance delay. The method according to any one of claims 1 to 3, The repeater donor, A first frame delay unit for bypassing a signal transmitted from a base station to the repeater remote and forwarding the base station signal by one frame and forwarding the signal through the first antenna in a forward signal processing; A second frame delay unit for delaying a signal received through the first antenna by one frame during reverse signal processing; And An adder which adds a reverse signal received from the repeater remote and a signal delayed by one frame from the second frame delay unit to the base station; In the portable Internet system comprising a base station and the relay period synchronization matching device. The method of claim 4, wherein The repeater remote, A first delay unit configured to delay the forward signal received from the repeater donor by '1 frame-wide distance delay' and transmit it through a second antenna during forward signal processing; And A second delay unit delaying a signal received through the second antenna by one frame-wide distance delay and transmitting the delayed signal to the repeater donor In the portable Internet system comprising a base station and the relay period synchronization matching device. The method of claim 5, wherein The repeater, A base station and relay period synchronous matching device in a portable internet system, characterized in that the time division duplex (TDD) repeater for the portable Internet. A method of synchronizing relay periods with a base station in a wireless communication system, In the forward signal processing, the repeater donor bypasses the signal transmitted from the base station to the repeater remote and simultaneously delays the base station signal by a first predetermined frame and sends it through the first antenna; In a forward signal processing, repeating, by a repeater remote, a forward signal received from the repeater donor by a second predetermined frame and transmitting the delayed forward signal through a second antenna; In a reverse signal processing, relaying the signal received through the second antenna to the repeater donor by delaying the signal received through the second antenna by the second predetermined frame; And In the reverse signal processing, the repeater donor delays the signal received through the first antenna by the first predetermined frame and adds the reverse signal received from the repeater remote to the base station. In the portable Internet system comprising a base station and the relay period synchronization matching method. The method of claim 7, wherein The first predetermined frame, A method of synchronizing relay periods with a base station in a portable Internet system, characterized by one frame. The method of claim 7, wherein The second predetermined frame is, A method of synchronizing relay periods with a base station in a portable Internet system, characterized in that one frame is obtained by subtracting a wide range delay. The method according to any one of claims 7 to 9, The repeater, A method of synchronizing relay periods with a base station in a portable Internet system, characterized by a time division duplex (TDD) repeater for portable Internet.

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